Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records
Reference
Endpoint:
two-generation reproductive toxicity
Remarks:
based on test type (migrated information)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1987-1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: acceptable well documented publication, which meets basic scientific principles
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)
Qualifier:
according to
Guideline:
EPA OTS 798.4700 (Reproduction and Fertility Effects)
Principles of method if other than guideline:
Twenty-eight 42-day-old pups/sex/group (F0) were exposed to toluene diisocyanate vapour (TDI; 80% 2,4-TDI, 20% 2,6-TDI) by inhalation at 0.0, 0.02, 0.08, or 0.3 ppm, 6 h/day, 5 days/week, for 10 weeks, then mated within groups for 3 weeks, with exposure 7 days/week during mating, gestation, and lactation. F0 maternal animals were not exposed from gestational day (gd) 20 through postnatal day (pnd) 4; maternal exposures resumed on pnd 5. Twenty-eight weanlings/sex/group continued exposure for 12 weeks (starting on pnd 28) and were bred as described above. F0 and F1 parents and ten F1 and F2 weanlings/sex/group were necropsied, and adult reproductive organs, pituitary, liver, kidneys, and upper respiratory tract (target organs) were evaluated histologically in ten/sex/group.
GLP compliance:
yes
Remarks:
This study was performed in compliance with U.S. Environmental Protection Agency (EPA) TSCA (Toxic Substances Control Act) good laboratory practice regulations (U.S. EPA, 1983).
Limit test:
no
Test material information:
Composition 1
Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS: 145 virgin female and 145 virgin male albino CDt (Sprague-Dawley) rats (Crl:CDt [SD]BR) - 28 days old upon arrival
- Source: Charles River Breeding Laboratories (Kingston, NY)
- Age at study initiation: (P) 42 days; (F1) 28 days
- Weight at study initiation: (P) Males: ca. 200 g; Females: ca. 150 g; (F1) Males: 125 -150 g; Females: 100-125 g
- Housing: housed initially two/same sex during quarantine and then singly, except for the cohabitation periods, for the duration of the study. During the quarantine, prebreed periods, mating, and most of gestation, rats were housed in stainless steel, wire mesh cages including during exposure periods. From gd 19 through parturition, and lactation until weaning, female rats were housed in plastic shoebox cages (19.0 x 10.5 x 8 in.) with Alpha-Drit (Shepherd Specialty Papers, Inc., Kalamazoo, MI) bedding during nonexposure periods. Deotized Animal Cage Boardt (Shepherd Specialty Papers, Inc., Kalamazoo, MI) was placed beneath the stainless steel cages and changed regularly.
- Diet (e.g. ad libitum): Certified Ground Rodent Chowt #5002, Ralston-Purina Company, St. Louis, MO ad libitum except during exposures, feed jars were changed weekly;
- Water (e.g. ad libitum): tap water (Municipal Authority of Westmoreland County, Greensburg, PA) ad libitum except during exposures
The water was delivered by an automatic watering system, with demand control valves mounted on each cage rack for rats in stainless steel cages. Female rats housed in shoebox cages received water by water bottles with stainless steel sipper tubes. Analyses of the feed and water for contaminants and of the feed for nutrient levels indicated all contaminant levels were below the maximum certified standards, and all nutrient levels were above the minimum certified standards.
- Acclimation period: quarantined for approximately 2 weeks, during which time they were weighed, examined by a veterinarian, and representative animals were subjected to fecal examination, serum viral antibody analysis, and histologic examination of selected organs. Results of the physical examination, serology, parasitology, and histopathology were negative for signs of infectious disease.

ENVIRONMENTAL CONDITIONS
- Temperature: 62–76°F; room temperature was recorded continuously (Cole-Parmer Hygrothermographt Seven-Day Continuous Recorder, Model No. 8368–00, Cole-Parmer Instrument Company, Chicago, IL).
- Humidity (%): 40–70% , relative humidity was recorded continuously (Cole-Parmer Hygrothermographt Seven-Day Continuous Recorder, Model No. 8368–00, Cole-Parmer Instrument Company, Chicago, IL).
- Photoperiod (hrs dark / hrs light): 12-h photoperiod

All animals were handled and treated at all times in conformance with the National Institutes of Health Guide (NIH, 1985).
Route of administration:
inhalation: vapour
Type of inhalation exposure (if applicable):
whole body
Vehicle:
air
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: TDI vapour was generated using a glass evaporator system similar in design to that described by Carpenter et al. (1975) and as described by Tyl et al. (1999). The four chambers employed in this study were rectangular in shape, constructed of glass and stainless steel (Wahmann Manufacturing Company, Timonium, MD), and measured approximately 2.1m x 1m x 2.1 m (height). Total volume in each chamber was approximately 4320 L. An orifice plate was positioned in the exhaust duct of the chamber and was connected to a Dwyer Magnehelic Pressure Gauge.
The chambers were illuminated with artificial room light. Within each chamber, the animal cages were rotated daily to compensate for any possible but undetected variation in chamber exposure conditions (i.e., concentration, temperature, relative humidity). A vapour distribution study involving six sampling positions each at 0.02 and 1.0 ppm indicated low coefficients of variation (3.0–7.4%) and, therefore, uniform distribution of toluene diisocyanate vapour within the range of target exposure concentrations employed.
- Method of holding animals in test chamber: Within each chamber, animal cages were rotated weekly to compensate for any possible variation in chamber exposure conditions (i.e., vapour concentration, temperature, or relative humidity).
- Temperature, humidity, pressure in air chamber: Temperature and relative humidity gauges were placed inside each chamber during exposures. Chamber temperature, relative humidity, and air- flow rate were recorded every 30 min during each 6-h exposure. Temperature measurements obtained from the inside surface of each evaporator during the exposure regimen using a Doric Trendicator Model 400A probe (Doric Scientific Division, San Diego, CA) ranged from 42 to 63°C.
- Air flow rate: Airflow in each chamber was approximately 1000–1500 L/min, with a t99 (theoretically derived time required for the chamber to reach 99% of the equilibrium concentration) of approximately 20 min.
- Air change rate: at least 14 air changes per h
- Other: Liquid toluene diisocyanate was metered from a syringe pump (Sage Instruments, Cambridge, MA) into a heated glass evaporator, similar in design to that described by Carpenter et al. (1975). The temperature in the evaporator was monitored and maintained at the lowest level sufficient to vaporize the liquid (46–60°C). The resultant vapour was carried into the chamber by a counter-current air stream that entered the bottom of the evaporator. Chamber atmospheres containing toluene diisocyanate were filtered before leaving an exhaust stack.

TEST ATMOSPHERE
- Brief description of analytical method used: Two Autostep Isocyanate paper tape monitoring devices (GMD Systems, Inc., Hendersonville, PA), one for 0.00, 0.02, 0.08, and one for 0.3 ppm, were used to measure TDI concentrations in the exposure chamber atmospheres. Both instruments, calibrated using a modified Marcali method for detection of TDI in air, were equally sensitive to detection of the 2,4- and 2,6-TDI isomers. Throughout the 235 days of exposure, generated TDI atmospheres were monitored by placing probes in the breathing zone of the animals approximately six times per each 6-h exposure. Control chamber atmospheres were measured six times daily for the first 11 exposure days and once per day thereafter.
The 2,4- and 2,6-TDI isomer concentrations in the exposure chamber atmospheres were measured prior to the onset of the F0 exposure period and on exposure day 143. Reverse phase high pressure liquid chromatography was used to separate and quantify the 2,4- and 2,6-isomers.
- Samples taken from breathing zone: yes (Samples were collected using glass fiber filters coated with 1-(-pyridylpiperazine), as well as impingers containing N-2-nitrobenzyl-n-m-propylamine in toluene. Samples were obtained through a sampling port located approximately 6 feet above the chamber floor and approximately 6 in. from the inside chamber wall. Probes for sampling were located within 2–3 in. of each other.)
- Other: Daily nominal concentrations (an estimated concentration calculated from the amount of test material delivered and the chamber airflow during the exposure period) were also calculated for each chamber.
Details on mating procedure:
- M/F ratio per cage: 1/1
- Length of cohabitation: 3 weeks (with no change of partners)
- Proof of pregnancy: Observations of vaginal sperm and/or dropped or vaginal copulation plug were considered evidence of successful mating (Hafez, 1970); the date of insemination was designated gd 0.
- After successful mating each pregnant female was caged individually.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The purity and stability of the test chemical were verified by analysis before, during, and after the study. The test material remained over 99% pure throughout the study. However, there were modest differences between the TDI isomer ratio in the test atmospheres as compared to the test material. The periodic analyses of the chamber atmospheres indicated that the mean analytical values of TDI +/- SD for the low (0.02 ppm), middle (0.08 ppm), and high (0.30 ppm) exposure concentrations were 0.020 +/- 0.003, 0.079 +/- 0.009, and 0.29 +/- 0.023 ppm, respectively. No test chemical was detected in the control atmospheres, with a minimum detection limit of 0.002 ppm.
Percentage of the concentrations of the 2,4- and 2,6-isomers in the chamber atmospheres (sampled on exposure day 143) were 63.4% and 36.6% for the low concentration exposure chamber, 69.2% and 30.8% for the mid concentration exposure chamber, and 75.0% and 25.0% for the high concentration exposure chamber. These data indicated that the 2,4-isomer content of 80% decreased approximately 15%, 10%, and 5% in the low, mid, and high concentration exposure chambers, respectively. Although the test material stability was verified before and after the study, the isomer ratio of TDI in the exposure chamber did not precisely match the 80/20 ratio of the test material. This may relate to the imperfect match of analytical to nominal concentrations, suggesting some loss of the test material during th vapor generation process. Given the very low (sub ppm) range of test concentrations of this reactive material, a modest difference in analytical to nominal ratio and the isomer ratio was not surprising. The differences were unlikely to have had a significant impact on the outcome or interpretation of the study.
Duration of treatment / exposure:
F0: 10 weeks (prebreed exposure period), 3 weeks (mating period) , exposure continued throughout gestation and lactation , except for the following interval: after the exposure on gd 19, each female was transferred to a shoebox cage and was not exposed from gd 20 through pnd 4. Exposures to the dam resumed on pnd 5.
F1: selected weanlings were exposed to TDI by inhalation for 12 weeks, then mated as described above, with exposure continuing during mating, gestation, and lactation.
Frequency of treatment:
5 days/week, 6 h/day (F0 premating period, F1 premating period), then 7 days/week, 6 h days for the remaining time (F0 and F1 mating and gestation, except gd19-pnd4).
Details on study schedule:
- F1 parental animals not mated until 1 week after selected from the F1 litters: After weaning on pnd 21, litters (minus the dam) were maintained for one additional week (until pnd 28) before direct exposures began to the selected F1 weanlings.
- Selection of parents from F1 generation when pups were 21 days of age.
- Age at mating of the mated animals in the study: 20 weeks

At weaning on pnd 21, 28 F1 weanlings/sex/group were randomly selected to be parents of the F2 generation.
Remarks:
Doses / Concentrations:
0.0 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0.02 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0.08 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0.3 ppm
Basis:
nominal conc.
No. of animals per sex per dose:
28 (F0), 28 (F1)
Control animals:
yes, concurrent no treatment
Details on study design:
- Dose selection rationale: To determine appropriate target concentrations of TDI, a range-finding study was performed following the same study design as in the definitive developmental study, except that eight inseminated females per group were employed, the exposure concentrations were 0.0, 0.1, 0.5, and 1.0 ppm (analytical concentrations 0.0 [, minimum detection limit of 1 ppb], 0.12 +/- 0.013, 0.48 +/- 0.018, and 0.95 +/- 0.093 ppm), and the dams were terminated after the last exposure on gd 15. At termination, immediately after the last exposure, the dams were anesthetized with methoxyflurane (Metofanet, Pittman-Moore) and arterial blood was removed from the abdominal aorta into arterial blood samplers (Carney Medical, Medfield, MA) containing heparin as an anticoagulant. Blood parameters directly measured were pH, pCO2 and pO2 (Corning Model 170 Blood Gas Analyzer, Corning Medical, Medfield, MA); HCO3- (bicarbonate) was calculated by the following formula: 0.031 *pCO2 3 10E(pH–6.1). Commercially available quality control samples (Certain, Level I, II, III, Corning Medical, Medfield, MA) were analysed prior to and following every 10 samples, with appropriate calibration checks immediately prior to sample analysis. The dams were then examined for body weight, gravid uterine weight, liver weight, number of ovarian corpora lutea, number of uterine implantation sites (total, early, and late absorptions, and dead implants [there were none]), and live implants. At 1.0 ppm, maternal body weights, weight changes, and liver weights (absolute but not relative) were profoundly and significantly reduced, audible respiration and nasal red discharge were observed; stomach and intestines were gas filled (due to gasping), and adrenal glands were enlarged (most likely due to stress). There were no effects of treatment on any gestational parameters, including pre- or postimplantation loss and percent live implants per litter at any exposure concentration tested. The maternal blood gas results include the following statistically significant changes at 1.0 ppm: reduced pH (1%), markedly increased pCO2 (31%), markedly decreased pO2 (33%), and slightly increased HCO3- (13%). These alterations are characteristic of respiratory acidosis resulting from compromised pulmonary function. Typically, as a result of impaired alveolar ventilation, arterial O2 levels are reduced, CO2 is inefficiently eliminated, and the bicarbonate levels rise to compensate for the increased CO2 levels. (Based on the slight increase in bicarbonate and the effects on pH, pCO2 and pO2, compensation was apparently not achieved.) Since this compensating change takes place over 2–3 days, the alterations are considered to be of a chronic nature. (The use of methoxyflurane as an anaesthetic may have confounded the blood gas results, as the pH of conscious control rats is usually 7.5 and the mean pH of the anesthetized control rats in this study was 7.38.) Based on these results, 1.0 ppm was deemed too toxic for use. The target exposure concentrations for the developmental study were, therefore, 0.00, 0.02, 0.10, and 0.50 ppm.
The rationale for the exposure concentrations of the two-generation toxicity study was based on the developmental toxicity study of TDI at 0.02, 0.10, and 0.50 ppm in the same rat strain (mentioned above). In that study, exposure to TDI vapour for six h/day, for gd 6 through 15 at 0.50 ppm, resulted in reductions in maternal body weight, body weight gain, and feed consumption. Because relatively major maternal indications of toxicity were observed at 0.50 ppm after only 10 days of exposure during gestation, there was concern that 0.50 ppm would result in excessive adult toxicity during the 10-week prebreed exposure and during the mating, gestation, and lactation periods (when exposure continued). Therefore, the top and middle target exposure concentrations were slightly lower for the present study.
- Rationale for animal assignment: Two hundred twenty-four animals were placed on study, 28/sex/group, by randomization procedures stratified by body weight, immediately prior to the start of the prebreed exposure period. All animals were assigned a unique number and were toe clipped and ear notched prior to the start of the study.
Positive control:
No details on positive controls available.
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: prebreed exposure: clinical observations recorded daily (mortality checks twice daily) and body weights recorded weekly

DETAILED CLINICAL OBSERVATIONS: No data
- Time schedule:

BODY WEIGHT: Yes
- Time schedule for examinations: weekly, Dams were weighed on gd 0, 7, 14, and 21. Dams with litters were weighed on pnd 1, 4, 7, 14, and 21.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: No (feed consumption was not recorded)
Estrous cyclicity (parental animals):
No details on oestrous cyclicity available.
Sperm parameters (parental animals):
No details on sperm parameters available.
Litter observations:
STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: [yes] Litters were randomly culled to a maximum of eight (with as equal sex ratio as possible) on pnd 4 (F1).
- If yes, maximum of 8 pups/litter (sex/litter as nearly as possible); excess pups were killed and discarded.
- F2 weanlings, ten/sex/group, were selected for necropsy; remaining F2 weanlings were examined externally, euthanized, and discarded.

PARAMETERS EXAMINED
The following parameters were examined in [F1 / F2 / F3] offspring:
Pups (F1 generation) were individually counted, sexed, and examined grossly on pnd 0, 1, 4, 7, 14, and 21. They were also weighed individually on pnd 1, 4, 7, 14, and 21.
At weaning on pnd 21, ten F1 weanlings/ sex/group were randomly selected for necropsy; remaining F1 weanlings were examined externally, euthanized, and discarded.
[number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain]

GROSS EXAMINATION OF DEAD PUPS:
[yes, for external and internal abnormalities]
A gross internal examination was also performed on any pup appearing abnormal or dying on test. As the necropsy of the randomly selected animals revealed no gross abnormalities, all remaining pups of all groups not used for the new parental generation were euthanized and discarded.
Postmortem examinations (parental animals):
SACRIFICE
- Male animals: All surviving animals after the delivery of F1 litters
- Maternal animals: All surviving animals after weaning of the F1 litters.
All F0 and F1 parental animals in all groups (both generations) were euthanized by severing the brachial blood vessels following anaesthesia with methoxyflurane, and subjected to a complete necropsy.

GROSS NECROPSY
- A complete necropsy and histopathologic examination were conducted for any parental animals dying on test.
- Gross necropsy consisted of examination of the external surfaces; all orifices; cranial cavity; carcass; external and cut surfaces of the brain and spinal cord; the thoracic, abdominal, and pelvic cavities and their viscera; and cervical tissues and organs.

HISTOPATHOLOGY / ORGAN WEIGHTS
Of the 28 male and 28 female adults from the control and high exposure groups, ten/sex/group were selected randomly and subjected to a histopathology examination. Histopathologic evaluation was conducted on the tissues specified below after fixation in buffered neutral 10% formalin, paraffin embedment, and sectioning and staining with hematoxylin and eosin: pituitary, liver, kidneys (two), upper and lower respiratory tract (including nasal turbinates), vagina, uterus, ovaries, testes, epididymides, seminal vesicles, prostate, and other tissues with gross lesions identified as being potentially treatment related. Any of the above organs or tissues showing gross or histopathologic alterations, specifically the upper respiratory tract (including the nose, nasal turbinates, larynx, and trachea), were also evaluated microscopically in ten animals/sex from the other treatment groups.
The fixed (buffered neutral 10% formalin) uteri from any parental female of the F0 or F1 generations failing to produce a litter were stained with potassium ferricyanide for confirmation of pregnancy status; implantation sites (if any) were recorded. This procedure did not affect the subsequent histopathologic examination.
Postmortem examinations (offspring):
SACRIFICE
- The F1 offspring not selected as parental animals and all F2 offspring were sacrificed at 21 days of age.
- These animals were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows:

GROSS NECROPSY
- - Gross necropsy consisted of examination of the external surfaces; all orifices; cranial cavity; carcass; external and cut surfaces of the brain and spinal cord; the thoracic, abdominal, and pelvic cavities and their viscera; and cervical tissues and organs.
A gross internal examination was performed on ten pups randomly selected for each sex from each test group of the F1 and F2 generations. As the necropsy of the randomly selected animals revealed no gross abnormalities, all remaining pups of all groups not used for the new parental generation were euthanized and discarded.

HISTOPATHOLOGY / ORGAN WEIGTHS
Histopathologic evaluation was conducted on the tissues specified below after fixation in buffered neutral 10% formalin, paraffin embedment, and sectioning and staining with hematoxylin and eosin: pituitary, liver, kidneys (two), upper and lower respiratory tract (including nasal turbinates), vagina, uterus, ovaries, testes, epididymides, seminal vesicles, prostate, and other tissues with gross lesions identified as being potentially treatment related. Any of the above organs or tissues showing gross or histopathologic alterations, specifically the upper respiratory tract (including the nose, nasal turbinates, larynx, and trachea), were also evaluated microscopically in ten animals/sex from the other treatment groups.
The fixed (buffered neutral 10% formalin) uteri from any parental female of the F0 or F1 generations failing to produce a litter were stained with potassium ferricyanide for confirmation of pregnancy status; implantation sites (if any) were recorded. This procedure did not affect the subsequent histopathologic examination.
Statistics:
The unit of comparison was the male, the female, or the litter (Weil, 1970). Results of the quantitative continuous variables (e.g., body weights, organ weights, etc.) were intercompared for the three treatment groups and one control group by use of Levene’s test for equal variances (Levene, 1960), analysis of variance (ANOVA), and t-tests. When Levene’s test indicated homogeneous variances and the ANOVA was significant, the pooled t-test was used for pairwise comparisons. When Levene’s test indicated heterogeneous variances, all groups were compared by an ANOVA for unequal variances (Brown and Forsythe, 1974) followed, when necessary, by the separate variance t-test for pairwise comparisons. The significance levels for the t-test comparisons were corrected by the Bonferroni method for all reproductive data. Nonparametric data were statistically evaluated using the Kruskal-Wallis test (Sokal and Rohlf, 1969), followed by the Mann-Whitney U test for pairwise comparisons (Sokal and Rohlf, 1969), when appropriate. Frequency data (such as the various indices) were compared using the Fischer’s exact test (Sokal and Rohlf, 1969). For all statistical tests, the fiducial limit of 0.05 (two-tailed) was used as the criterion for statistical significance.
Reproductive indices:
No. mating pairs, Mating index, Fecundity index, Fertility index, Gestational index, Gestational length, days, No. live litters, pnd 0, No. live litters, pnd 21, Live birth index, Survival indices, 4-day (pnd 0—4 precull), 7-day (pnd 4 postcull-7), 14-day (pnd 7-14), 21-day (pnd 14-21), Lactation index (pnd 4-21 postcull)


Offspring viability indices:
pnd 0: No. live litters, No. total pups/litter, No. live pups/litter, % males/litter
pnd 1:No. live litters, Pup body weight/litterb,
pnd 4 (precull): No. live litters, No. pups/litter, % males/litter, Pup body weight/litter, Pup weight gain/litter, pnd 1-4b
pnd 7: No. live litters, No. pups/litterd, % males/litter, Pup body weight/litter, Pup weight gain/litter, pnd 4-7
pnd 14: No. live litters, No. pups/litter, % males/litter, Pup body weight/litter, Pup weight gain/litter, pnd 7-14
pnd 21: No. live litters, No. pups/litter, % males/litter, Pup body weight/litter, Pup weight gain/litter, pnd 14-21
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
F0 males: increased incidence of nasal discharge at 0.3 ppm. F0 females: increased incidence of red-tinged fur about the head at 0.3 ppm. Periocular encrustation, perinasal encrustation and/or red nasal discharge in all exposure groups.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Final male bw (0.3 ppm, week 14) stat. increased. Male F0 bw gains (0.3 ppm, 1 week) reduced, (weeks 4-5 and 8-9) sig. increased terminal F0 male bw gains sig. increased at 0.02, 0.08, and 0.3 ppm. Females (0.3 ppm, week 18–19) sig. increased bw gain. f
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Final male bw (0.3 ppm, week 14) stat. increased. Male F0 bw gains (0.3 ppm, 1 week) reduced, (weeks 4-5 and 8-9) sig. increased terminal F0 male bw gains sig. increased at 0.02, 0.08, and 0.3 ppm. Females (0.3 ppm, week 18–19) sig. increased bw gain. f
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
no effects observed
Description (incidence and severity):
There were no treatment-related gross lesions observed at necropsy.
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Treatment-related histopathologic lesions were limited to the upper respiratory tract, with tissues located deeper in the respiratory tract being less affected. (rhinitis, alterations like dysplasia & hyperplasia of the nasal epithelium in the turbinates.
Other effects:
not specified
Reproductive function: estrous cycle:
no effects observed
Description (incidence and severity):
There was no effect of treatment on reproductive organs or functions.
Reproductive function: sperm measures:
no effects observed
Description (incidence and severity):
There was no effect of treatment on reproductive organs or functions.
Reproductive performance:
no effects observed
Description (incidence and severity):
Reproductive parameters of F0 parents to produce F1 offspring were unaffected by treatment. Gestational length was unaffected by exposure to the test chemical. F1 live birth and survival indices were unaffected by treatment.
CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
Treatment-related clinical signs of toxicity in F0 males included an increased incidence of nasal discharge at 0.3 ppm. F0 females exhibited an increased incidence of red-tinged fur about the head at 0.3 ppm. Periocular encrustation, perinasal encrustation, and/or red nasal discharge were observed in all exposure groups of F0 males and females, including the control group, and appeared to be associated with the inhalation treatment conditions per se rather than exposure to the test chemical vapour.
Two F0 adult animals died during the conduct of this study: one female and one male. One F0 female at 0.02 ppm died of an abnormal pregnancy with uterine bleeding. The cause of death of the one F0 male at 0.3 ppm, found dead on study day 85, was not determined, although the animal had microscopic lesions of the respiratory tract similar to those of other animals in its exposure group.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
During the 10-week prebreed exposure and 3-week mating periods of the F0 animals, male body weights were equivalent across all treatment groups. Final male body weights (week 14) were statistically increased at 0.3 ppm. Male F0 weight gains at 0.3 ppm were reduced for the first exposure week and were significantly increased for treatment weeks 4–5 and 8–9; terminal F0 male body weight gains were significantly increased at 0.02, 0.08, and 0.3 ppm. Female F0 body weights exhibited no significant differences among groups during the prebreed exposure period or during the final exposure week. F0 female weight gains exhibited a similar equivalence across treatment groups for the prebreed exposure period. During the final week of exposure (week 18–19), females at 0.3 ppm exhibited a significantly increased weight gain.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
Maternal F0 gestational and lactational body weights and weight gain were equivalent across all exposure groups. Reproductive parameters of F0 parents to produce F1 offspring were unaffected by treatment. Gestational length was unaffected by exposure to the test chemical. F1 live birth and survival indices were unaffected by treatment. F1 litter sizes, sex ratio (% males), and pup body weights and weight gains (by litter and by sex by litter) were equivalent across all treatment groups from lactational day 1 through 21. No treatment-related lesions were observed in the F1 pups, which died during the lactation period.

GROSS PATHOLOGY (PARENTAL ANIMALS)
There were no treatment-related gross lesions observed at necropsy.

HISTOPATHOLOGY (PARENTAL ANIMALS)
Treatment-related histopathologic lesions were limited to the upper respiratory tract, with tissues located deeper in the respiratory tract being less affected. In both F0 males and females at 0.3 ppm, the most frequently observed lesions were rhinitis and alterations (dysplasia and hyperplasia) of the respiratory (nasal) epithelium in the nasal turbinates. Increased incidences of rhinitis were also observed in nasal turbinates of F0 males and females at 0.08 and 0.02 ppm, relative to the F0 control males (one) and females (none). At 0.02 ppm, three F0 males exhibited rhinitis, one minimal multifocal and two mild multifocal; three F0 females at 0.02 ppm also exhibited rhinitis, one minimal multifocal and two mild (one each focal and multifocal).
Dose descriptor:
NOAEL
Remarks:
adult toxicity
Sex:
male/female
Basis for effect level:
other: not determined
Remarks on result:
not measured/tested
Remarks:
Effect level not specified (migrated information)
Dose descriptor:
NOAEL
Remarks:
reproductive toxicity
Effect level:
0.3 ppm
Basis for effect level:
other: the NOAEL for reproductive toxicity was at least 0.3 ppm
Remarks on result:
other: Generation not specified (migrated information)
Dose descriptor:
NOAEL
Remarks:
postnatal toxicity
Effect level:
0.02 ppm
Basis for effect level:
other: the NOAEL for postnatal toxicity was 0.02 ppm
Remarks on result:
other: Generation not specified (migrated information)
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
perinasal encrustation across all treatment groups in F1 females, the incidence was sig. increased at 0.3 ppm. Incidence of red-tinged fur in F1 males, was sig. increased in F1 females at 0.08 & 0.3 ppm from 17 to 22 weeks (study days 120-155) of exposure
Mortality / viability:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
consisting of reduced body weights and body weight gains
Sexual maturation:
no effects observed
Description (incidence and severity):
Maternal F1 gestational & lactational bw /bw changes were unaffected for all time points. Gestational length was unaffected. F2 pup live birth & survival indices were unaffected. F2 litter size and sex ration (%males) were unaffected.
VIABILITY (OFFSPRING)
not affected

CLINICAL SIGNS (OFFSPRING)
In F1 males, there were no significant treatment- or concentration-related changes in incidence of clinical observations. Although perinasal encrustation was observed across all treatment groups in F1 females, the incidence was significantly increased at 0.3 ppm. The incidence of red-tinged fur, although occasional in TDI-exposed F1 males, was significantly increased in F1 females at 0.08 and 0.3 ppm from 17 to 22 weeks (study days 120–155) of exposure.
The red-tinged fur is from chromo- dacryorrhea, red-brown material (porphyrin) secreted from the Harderian gland and distributed about the face and neck by normal grooming activity (Seely, 1987). It is a relatively non-specific indication of stress. It is likely that this stress-related finding is associated with the longer duration of females’ exposure to TDI.

BODY WEIGHT (OFFSPRING)
During the 12-week prebreed exposure of the F1 animals randomly selected to be parents of the F2 generation, the males at 0.3 ppm exhibited reduced body weights relative to the controls for the first 4 weeks of exposure. For weekly intervals 0–1 and 1–2, as well as the final week of exposure (week 15–16), body weight gains were significantly reduced at 0.3 ppm. F1 males at 0.02 ppm exhibited significantly increased body weight gain relative to controls for weekly intervals 12–13 and 13–14 of the mating period. The F1 females exhibited reduced body weights at 0.3 ppm for the first 2 weeks of exposure, as well as week 6 of exposure. There were no significant differences among groups for F1 female weight gain.

SEXUAL MATURATION (OFFSPRING)
Maternal F1 gestational and lactational body weight and body weight changes were unaffected for all time points measured. Gestational length was unaffected by exposure. F2 pup live birth and survival indices were unaffected by treatment. F2 litter size and sex ratio (% males) were unaffected by treatment. At 0.3 ppm, F2 pup body weight per litter exhibited reductions (males, females, and all pups) beginning on pnd 14 and persisting through day 21 for male pups. Body weights of female pups and all pups/litter were also reduced on lactation day 14 at 0.08 ppm. Pup body weight gains per litter (males, females, and all pups) were reduced at 0.08 and 0.3 ppm for pnd 4 to 7, and at 0.3 ppm pup body weight gain reductions persisted (males, females, and all pups) through pnd 14.

ORGAN WEIGHTS (OFFSPRING)
no details available

GROSS PATHOLOGY (OFFSPRING)
Three F1 females were sacrificed prior to scheduled sacrifice and included one animal at 0.08 ppm on study day 94 due to traumatic injury, and one animal each at 0.3 ppm and 0.08 ppm due to early deliveries during exposure.
After delivery (F1 males) or weaning (F1 females) of the F2 litters, all surviving F1 parental animals were necropsied. No gross treatment-related lesions were observed. Selected tissues were examined histologically on ten animals per sex from high exposure and control animals. The one target tissue, the upper respiratory tract, including nasal turbinates, larynx, and trachea, was also examined microscopically from ten animals/sex from all groups. As with F0 parents, histologic lesions were limited to the upper respiratory tract (nasal cavities, larynx, and trachea). Although dysplasia and/or hyperplasia of the nasal respiratory epithelium were present in F1 parents at 0.08 and 0.3 ppm, the frequency of occurrence was not significantly increased relative to the control frequency. Rhinitis was observed with increased frequencies in all TDI-exposed groups of F1 males and females (with no rhinitis observed in the control animals). Seven of the ten F1 males and four of the ten F1 females examined at 0.02 ppm exhibited rhinitis; in the seven males with rhinitis, six were classified as minimal multifocal and one as moderate multifocal; in the four females with rhinitis, one was minimal focal, one was mild multifocal, and two were moderate multifocal (Table 4). Mononuclear cell infiltration of liver tissue, although present in controls and significantly increased in F1 females at 0.3 ppm, was not deemed treatment related. No treatment-related gross lesions were observed in F2 pups that died during lactation, or in the ten/sex/group subjected to necropsy at weaning.

HISTOPATHOLOGY (OFFSPRING)
Necropsy of ten randomly selected F1 pups/sex/group indicated no treatment-related gross findings.
Reproductive effects observed:
not specified

    TABLE1        
    Chamber Analyses        
   Target concentrations (ppm)     
  0.00 0.02 0.08 0.3
Analytical concentrations (ppm)a        
Paper tape method <MDLS 0.020±0.0026 0.079 ± 0.0088 0.29 ± 0.023
Corrected by modified Marcali method <MDL 0.018±0.0023 0.070 ± 0.0077 0.23 ± 0.020
A/T ratio'        
Paper tape method 1.00 0.99 0.97
Corrected by modified Marcali method 0.90 0.88 0.77
Nominal Concentrations (ppm)d 0.045 ± 0.0049 0.127 ± 0.017 0.39 ± 0.027
A/N ratioe        
Paper tape method 0.44 0.64 0.74
Corrected by modified Marcali method 0.38 0.56 0.60
2,4-Isomer/2,6-isomer ratio7 1.7:1.0 2.2:1.0 3.0:1.0
Temperature (°C)g 24.1±1.17 24.7 ± 0.99 24.2 ± 0.92 25.0 ± 1.02
Relative humidity (%)g 49.5±4.80 46.0 ± 4.18 47.6 ± 4.49 47.6 ± 5.33
aGrand mean of 230 (0.02 ppm) or 235 (0.08 and 0.3 ppm) daily means ± standard deviation.      
bLess than the minimum detection limit of 0.002 ppm.         
cAnalytical to target concentration ratio.            
dGrand mean of 229 (0.02 ppm), 234 (0.08 ppm), or 235 (0.3 ppm) daily means ± standard deviation.      
eAnalytical to nominal concentration ratio.            
fIsomer ratio of the test chemical is 4.0:1.0 (80%/20%); these data are from "grab" samples taken during the exposures (see text).   
gGrand mean of 233 (0.0 ppm), 230 (0.02 ppm) or 234 (0.08 and 0.3 ppm) daily means for temperature and relative humidity ± standard deviation.
Significant treatment-related histologic findings were limited to changes in the upper respiratory tract, including minimal to moderate rhinitis at all exposure levels in F0 and F1 adult males and females. At 0.02 ppm, there were three (of ten) F0 males, seven F1 males, three F0 females, and four F1 females; at 0.08 ppm, there were eight (of ten) F0 males, five F1 males, six F0 females, and four F1 females; at 0.30 ppm, there were nine (of ten) F0 males, nine F1 males, nine F0 females, and nine F1 females, relative to the control incidence of no F1 males and F0 and F1 females, and one F0 male, out of ten/sex/group examined in each generation.

Rhinitis is a typical response of the rodent to an irritant material, and similar effects have been reported in response to well-known irritants such as chlorine (Barrow et al., 1979), acrolein (Feronet al., 1978), sulfur dioxide (Giddens and Fairchild, 1972), and acetaldehyde (Kruysse et al., 1975). The rat is regarded as the most sensitive of the commonly used laboratory species in its response to these irritants.

Because the rhinitis is localized in the most anterior portion of the upper respiratory tract, the proximate site of contact of TDI, this finding can be viewed as an essentially localized, nonspecific response to exposure to an irritating vapour. Other histologic findings only at 0.3 ppm, specifically dysplasia and/or hyperplasia of the nasal respiratory epithelium, were indicative of more severe irritant effects of TDI.

       TABLE2              
       productive Parameters              
   F0 (TDI, ppm)          F1 (TDI, ppm)     
  0.0 0.02 0.08 0.30 0.0 0.02 0.08 0.30
No. mating pairs 28 28 28 28 28 28 28 28
Mating index" 96.4 100.0 96.4 100.0 89.3 100.0 92.9 100.0
Fecundity index" 88.9 78.6 96.3 89.3 88.0 75.0 80.8 89.3
Fertility index"-' 85.7 78.6 92.9 89.3 78.6 75.0 75.0 89.3
Gestational index" 100.0 95.5 100.0 100.0 100.0 100.0 100.0 100.0
Gestational length, days 21.9 ± 0.3c 21.9 ± 0.4 21.9 ± 0.3 22.0 ± 0.06 21.9 ± 0.3 22.0 ± 0.6 22.0 ± 0.4 22.2 ± 0.5
No. live litters, pnd0 24 21 26 25 22 21 21 25
No. live litters, pnd21 23 20 25 24 21 21 20 25
Live birth index 97.7 ± 6.31c 97.0 ± 5.96 98.2 ± 4.71 98.7 ± 3.41 97.4 ± 4.67 95.2 ± 10.21 96.8 ± 7.76 98.5 ± 4.31
Survival indices"                
4-day (pnd0—4precull) 94.6 ± 20.35c 93.8 ± 21.71 93.9 ± 19.80 94.5 ± 20.12 94.3 ± 21.30 97.3 ± 3.95 93.9 ± 21.70 97.3 ± 6.16
7-day (pnd4postcull-7) 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00 100.00 ± 0.00
14-day (pnd7-14) 100.0 ± 0.00 100.0 ± 0.00 99.5 ± 2.50 99.5 ± 2.55 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00
21-day (pnd14-21) 100.0 ± 0.00 99.4 ± 2.80 100.0 ± 0.00 99.5 ± 2.55 99.4 ± 2.73 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00
Lactation index (pnd 4-21 postcull) 100.0 ± 0.00 99.4 ± 2.80 99.5 ± 2.50 99.0 ± 3.53 99.4 ± 2.73 100.0 ± 0.00 100.0 ± 0.00 100.0 ± 0.00
Indices                
Mating index(%) = (Number of females with copulation plugs/ Number of females cohabited) *100                 
Fecundity index(%) = (Number of pregnancies / Number of plug-positive females)*100
Fertility index (female)(%) =(Number of females pregnant / Number of females cohabited)*100                 
Fertility index (male)(%) = (Number of males shown to be fertile / Total number of males mated)*100                
Gestational index(%) = (Number of females with live litters / Number of females pregnant)*100             
Live birth index(%) = (Number of live pups at birth / Total number of pups born)*100                
Survival indices(%) = (Number of live pups indicated on postnatal day / Total number of live pups on previous index day)*100 ; from 7-day through lactation index, based on postcull survivors.  
Lactation index(%) = (Number of pups surviving 21 days / Total number of live pups at 4 days(postcull))*100         
Fertility index is the same for both males and females; mating was 1:1 with no change in partners
Data are presented as mean ± SD
No reproductive parameters were affected during either generation (F1 or F2). During the breeding phases for the F0 and F1 females, there were no treatment-related changes in gestational body weights or lactational body weights. F2 (but not F1) litters exhibited reduced body weights at 0.3 ppm for lactational days 14 and 21, and at 0.08 ppm for lactational day 14 only. Lactational body weight gains were reduced in F2 (but not F1) litters at 0.08 ppm for lactational days 4–7 and at 0.3 ppm for lactational days 4–7 and 7–14. Reduced pup body weight gain per litter at 0.08 and 0.3 ppm, observed during the lactation period (only for the F2 generation), initially occurred during the interval lactational days 4–7, when removal of the dams from the nest was reinstated for exposures (beginning on lactational day 5) in all groups. Removal of the dams for more than 6 h/day reduced pups' access to their food supply (the lactating dam) and was most likely compounded by the dams’ discomfort at 0.08 and 0.3 ppm upon return to the nest after the daily exposures. The effects at 0.08 ppm were resolved during the last week of lactation. There were no effects on F1 or F2 offspring body weights or weight gains at 0.02 ppm.
TABLE 3
Offspring Litter Size, Sex Ratio, Body Weights, and Weight Gain during Lactation
   F1 offspring (TDI, ppm)          F2 offspring (TDI, ppm)     
0.0 0.02 0.08 0.30 0.0 0.02 0.08 0.30
pnd 0                
No. live litters 24 21 26 25 22 21 21 25
No. total pups/litter 13.8±2.51° 14.1 ± 2.14 13.1 ± 3.19 14.2±3.53 13.9 ± 3.35 12.8 ± 3.36 13.6±2.91 13.6±2.66
No. live pups/litter 13.5±2.30 13.6±1.94 13.0±3.34 14.0±3.49 13.5 ± 3.38 12.4 ± 3.65 13.1 ± 3.05 13.4±2.74
% males/litter 49.6±12.9 48.0±12.4 45.6 ± 14.5 50.7 ± 15.7 48.6 ± 13.3 50.8 ± 15.3 48.6 ± 20.2 46.5±12.5
pnd 1                
No. live litters 23 21 26 24 22 21 21 25
Pup body weight/litterb 7.20±0.72 7.06 ± 0.78 7.04 ± 0.75 6.73 ± 0.71 7.08 ± 1.06 7.09 ± 1.03 7.04 ± 0.70 7.10±0.75

pnd 4(precull)

               
No. live litters 23 20 25 24 21 21 20 25
No. pups/litter 13.3 ± 2.40 13.5 ± 1.96 13.0±2.94 14.3± 2.18c 13.2±3.35 12.1 ± 3.65 13.2±2.86 13.0±2.74
% males/litter 50.3 ± 13.0 47.8±12.3 45.5 ± 14.6 53.0 ± 11.9 48.8 ± 13.7 51.4±15.8 50.1 ± 20.0 46.1±12.5
Pup body weight/litter 10.19±1.00 9.71 ± 1.12 9.96 ± 1.37 9.46 ± 1.27 10.19±1.82 10.48 ± 1.88 9.93 ± 1.13 10.28 ± 1.28
Pup weight gain/litter, pnd 1-4b 2.99 ± 0.73 2.60 ± 0.80 2.92 ± 0.74 2.72 ± 0.70 3.09 ± 1.02 3.39 ± 1.07 2.89 ± 0.83 3.18 ± 0.74
pnd 7                
No. live litters 23 20 25 24 21 21 20 25
No. pups/litterd 8.0 ± 0.00 8.0 ± 0.00 7.9 ± 0.28 8.0 ± 0.00 7.8 ± 1.09 7.5 ± 1.50 7.8 ± 1.12 8.0 ± 0.20
% males/litter 50.0 ± 6.5 48.8 ± 3.8 46.2 ± 9.5 50.5 ± 4.5 50.8 ± 5.4 50.4 ± 7.7 51.9±14.2 50.3 ± 3.9
Pup body weight/litter 14.89 ± 1.25 14.42±1.56 14.91 ± 1.59 14.02 ± 1.66 15.38 ± 2.41 15.25 ± 2.13 14.23 ± 1.66 14.68 ± 1.46
Pup weight gain/litter, pnd 4-7 4.70 ± 0.60 4.71 ± 0.72 4.95 ± 0.66 4.57 ± 0.78 5.19 ± 0.92 4.77 ± 0.72 4.29±1.08** 4.39 ± 0.93*
pnd 14                
No. live litters 23 20 25 24 21 21 20 25
No. pups/litter 8.0 ± 0.00 8.0 ± 0.00 7.9 ± 0.33 8.0 ± 0.20 7.8 ± 1.09 7.5 ± 1.50 7.8 ± 1.12 8.0 ± 0.20
% males/litter 50.0 ± 0.0 48.8 ± 3.8 45.9 ± 9.5 50.7 ± 3.9 50.8 ± 5.4 50.4 ± 7.7 51.9±14.2 50.3 ± 3.9
Pup body weight/litter 28.14±2.17 27.74 ± 3.21 28.72 ± 2.42 26.71 ± 2.67 29.79 ± 3.56 29.35 ± 3.50 27.51 ± 2.24* 27.33 ± 2.13*
Pup weight gain/litter, pnd 7-14 13.25 ± 1.92 13.32±2.10 13.81 ± 1.53 12.69±1.80 14.41 ± 1.64 14.10±1.94 13.28 ± 1.25 12.66±1.42**
pnd 21                
No. live litters 23 20 25 24 21 21 20 25
No. pups/litter 8.0 ± 0.00 8.0 ± 0.00 7.9 ± 0.33 7.9 ± 0.28 7.7 ± 1.10 7.5 ± 1.50 7.8 ± 1.12 8.0 ± 0.20
% males/litter 50.0 ± 6.5 48.4 ± 4.0 45.9 ± 9.5 51.0±4.0 50.5 ± 5.69 50.4 ± 7.7 51.9±14.2 50.3 ± 3.9
Pup body weight/litter 46.17±3.87 45.74 ± 4.59 46.99 ± 3.86 44.51 ± 4.88 49.03 ± 5.79 48.97 ± 6.20 46.18 ± 3.68 45.47± 3.64e
Pup weight gain/litter, pnd 14-21 18.04 ± 2.19 18.00±1.92 18.27 ± 2.10 17.76±2.66 19.23 ± 2.88 19.62 ± 2.99 18.67 ± 1.83 18.14±1.81
aData are presented as mean ± S.D.
bPup body weight and weight gain in grams, sexes combined.
cThe mean number of pups/litter was higher on pnd 4 than on pnd 0, since one litter with seven live pups, present on pnd 0 (so n= 25) had no live pups on pnd 4 (so n = 24).
dLitters culled to eight pups on pnd 4.
ePup body weight per litter was significantly reduced (p < 0.05) for male pups only, not for female or total pups per litter.
*p< 0.05 versus control group value.
**p< 0.01 versus control group value.

Continued inhalation exposure to TDI vapour for two generations in CDt (Sprague-Dawley) rats resulted in parental toxicity at 0.02, 0.08, and 0.3 ppm, evidenced by occasional body weight and weight gain depression and clinical signs of toxicity at 0.08 and 0.3 ppm, and histologic changes in the nasal cavities in both sexes and both generations at 0.02, 0.08, and 0.3 ppm. Postnatal toxicity, consisting of reduced body weights and body weight gains, occurred only in F2 litters at 0.08 and 0.3 ppm. There was no effect of treatment on reproductive organs or functions. No adult no observable adverse effect level (NOAEL) was identified, although the rhinitis observed at 0.02 ppm was considered a mild, nonspecific response to an irritant. The reproductive NOAEL was at least 0.3 ppm, and the postnatal toxicity NOAEL was 0.02 ppm in rats, under the conditions of this study.

Table 4 F0         
Incidence of Rhinitis in F0 and F1 parental animals                     
   F0(TDI, ppm)          Fl(TDI, ppm)        
  0.0 0.02 0.08 0.30 0.0 0.02 0.08 0.30
Males                        
No. examined 10 10 10 10 10 10 10 10
Rhinitis 1 3 8 9 0 7 5 9
Minimal 0 1 0 0   6 3 2
Focal   0       0 0 1
Multifocal   1       6 3 1
Diffuse   0       0 0 0
Mild 1 2 4 6   0 1 3
Focal 0 0 0 0     0 0
Multifocal 1 2 4 3     1 3
Diffuse 0 0 0 3     0 0
Moderate 0 0 4 3   1 1 4
Focal     0 0   0 0 0
Multifocal     4 2   1 1 4
Diffuse     0 1   0 0 0
Females                        
No. examined 10 10 10 10 10 10 10 10
Rhinitis 0 3 6 9 0 4 5 9
Minimal   1 2 2   1 4 5
Focal   0 0 0   1 0 0
Multifocal   1 2 2   0 4 5
Diffuse   0 0 0   0 0 0
Mild   2 3 4   1 1 3
Focal   1 0 0   0 0 0
Multifocal   1 2 4   1 1 3
Diffuse   0 1 0   0 0 0
Moderate   0 1 3   2 0 1
Focal     0 0   0   0
Multifocal     0 3   2   0
Diffuse     1 0   0   1
Note. The upper respiratory tracts, including the nose, nasal turbinates, larynx, and trachea, from ten parental animals/sex/group/generation, were examined histopathologically. The findings for rhinitis are presented by incidence, degree (minimal, mild, or moderate), and distribution (focal, multifocal, or diffuse).
Conclusions:
The study on toluene diisocyanate was performed according to the OECD Guideline 416 without deviations and according to the good laboratory practice principles, it is considered to be of high quality (reliability Klimisch 2). The criteria of validity of the test system are fulfilled. There was no reproductive toxicity, reproductive organ pathology, or effect on gestation or lactation at any exposure concentration. Postnatal toxicity and reduced body weights and weight gains during lactation occurred only in F2 litters at 0.08 and 0.3 ppm.
Executive summary:

The toxicity to reproduction of toluene diisocyanate was investigated in CD rats according to OECD TG416 (Märtins, 1989). The test substance was administered to the rats via inhalation (0, 0.02, 0.08 or 0.3 ppm, 6 h/day, 5 day/week) for a total of 10 weeks, then mated within groups for 3 weeks, with exposure 7 days/week during mating, gestation, and lactation. F0 maternal animals were not exposed from gestational day (gd) 20 through postnatal day (pnd) 4; maternal exposures resumed on pnd 5. Twenty-eight weanlings/sex/group continued exposure for 12 weeks (starting on pnd 28) and were bred as described above. F0 and F1 parents and ten F1 and F2 weanlings/sex/group were necropsied, and adult reproductive organs, pituitary, liver, kidneys, and upper respiratory tract (target organs) were evaluated histologically in ten/sex/group. Adult toxicity was observed in both sexes and generations at 0.08 and 0.3 ppm, including occasional reductions in body weights and weight gain, clinical signs of toxicity at 0.08 and 0.3 ppm, and histologic changes in the nasal cavities at 0.02, 0.08, and 0.3 ppm (including rhinitis, a nonspecific response to an irritating vapour, at all concentrations). There was no reproductive toxicity, reproductive organ pathology, or effect on gestation or lactation at any exposure concentration. Postnatal toxicity and reduced body weights and weight gains during lactation occurred only in F2 litters at 0.08 and 0.3 ppm. Therefore, under the conditions of this study, a no observed adverse effect level (NOAEL) was not determined for adult toxicity; the NOAEL for reproductive toxicity was at least 0.3 ppm, and the NOAEL for postnatal toxicity was 0.02 ppm.

Effect on fertility: via inhalation route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEC
3.5 mg/m³
Study duration:
subchronic
Species:
rat
Quality of whole database:
well-documented study, which meets basic scientific principles
Additional information

The toxicity to reproduction of toluene diisocyanate was investigated in CD rats according to OECD TG416 (Märtins, 1989). The test substance was administered to the rats via inhalation (0, 0.02, 0.08 or 0.3 ppm, 6 h/day, 5 day/week) for a total of 10 weeks, then mated within groups for 3 weeks, with exposure 7 days/week during mating, gestation, and lactation. F0 maternal animals were not exposed from gestational day (gd) 20 through postnatal day (pnd) 4; maternal exposures resumed on pnd 5. Twenty-eight weanlings/sex/group continued exposure for 12 weeks (starting on pnd 28) and were bred as described above. F0 and F1 parents and ten F1 and F2 weanlings/sex/group were necropsied, and adult reproductive organs, pituitary, liver, kidneys, and upper respiratory tract (target organs) were evaluated histologically in ten/sex/group. Adult toxicity was observed in both sexes and generations at 0.08 and 0.3 ppm, including occasional reductions in body weights and weight gain, clinical signs of toxicity at 0.08 and 0.3 ppm, and histologic changes in the nasal cavities at 0.02, 0.08, and 0.3 ppm (including rhinitis, a nonspecific response to an irritating vapour, at all concentrations). There was no reproductive toxicity, reproductive organ pathology, or effect on gestation or lactation at any exposure concentration. Postnatal toxicity and reduced body weights and weight gains during lactation occurred only in F2 litters at 0.08 and 0.3 ppm. Therefore, under the conditions of this study, a no observed adverse effect level (NOAEL) was not determined for adult toxicity; the NOAEL for reproductive toxicity was at least 0.3 ppm (corresponds to 3.5 mg/m³ for TRIDI), and the NOAEL for postnatal toxicity was 0.02 ppm.


Short description of key information:
Toxicity to reproduction - Read across from Toluene diisocyanate, (Märtins et al., 1989): two generation reproduction toxicity study: similar to OECD TG 416, CD rats, inhalation, doses 0, 0.02, 0.08 and 0.3 ppm, NOAEC for reproductive toxicity 0.3 ppm for rats (corresponds to 3.5 mg/m³ for TRIDI).

Justification for selection of Effect on fertility via inhalation route:
No studies for reproductive toxicity are available for TRIDI. Therefore, a study in rats conducted with TDI, the nearest analogue, is used for the DNEL derivation and further risk assessment.

Effects on developmental toxicity

Description of key information
Developmental toxicity - Read across from Toluene diisocyanate, Tyl et al, 1999, according to EPA OTS 798.4350 (Inhalation Developmental Toxicity Screen), CD rats, inhalation,  doses 0.00, 0.02, 0.10, or 0.50 ppm,  NOAEL 0.1 ppm (corresponds to 1.2 mg/m³ for TRIDI) for maternal and developmental toxicity.
Link to relevant study records
Reference
Endpoint:
developmental toxicity
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1986-1989
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable well documented publication, which meets basic scientific principles
Reference:
Composition 0
Qualifier:
according to
Guideline:
EPA OTS 798.4350 (Inhalation Developmental Toxicity Screen)
Principles of method if other than guideline:
Mated female CD (Sprague-Dawley) rats, 25/group, were exposed to toluene diisocyanate (TDI) vapour, for six h/day on gestational days (gd) 6 through 15, at 0.00, 0.02, 0.10, or 0.50 p.p.m. Maternal clinical signs, body weights, and feed and water consumption were recorded throughout gestation. At termination (gd 21), maternal body, gravid uterine, and liver weights were recorded. Corpora lutea were counted, and implantation sites were identified: resorptions and dead and live fetuses. All live fetuses were examined for external alterations. One-half of the live fetuses/litter were examined for visceral (including craniofacial) alterations. The remaining intact fetuses/litter were stained with alizarin red S and examined for ossified skeletal alterations.
GLP compliance:
yes
Remarks:
This study was performed in compliance with U.S. Environmental Protection Agency (EPA) TSCA (Toxic Substances Control Act) good laboratory practice regulations (U.S. EPA, 1983).
Limit test:
no
Test material information:
Composition 1
Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
TEST ANIMALS: 188 virgin female and 187 virgin male (COBS) CDt (SD)BR outbred albino rats, referred to as the CD (Sprague-Dawley) rat - 63 (males) and 56 (females) days old upon arrival
- Source: Charles River Breeding Laboratories (Kingston, NY)
- Age at study initiation: (P) 42 days; (F1) 28 days
- Weight at study initiation: (P) Males: ca. 200 g; Females: ca. 150 g; (F1) Males: 125 -150 g; Females: 100-125 g
- Housing: individually housed (cage dimensions, 22.5 * 15.5 * 18 cm high) for the duration of the study (except during exposures). For exposures, plug-positive females were transferred to stainless steel wire mesh exposure cages (35 cm * 17 cm * 18 cm high) in cage carriers that were moved onto the chambers. After each exposure, animals were returned to their original cages and “home” room. Paperboard (Deotized Animal Cage Boardt, Shepherd Specialty Papers, Inc., Kalamazoo, MI) was placed beneath the cages.
control data indicated that these animals were in good health and suitable for use.
- Diet (e.g. ad libitum):Certified feed (Purina Certified Ground Rodent Chowt, No. 5002, Ralston Purina Co., St. Louis, MO) ad libitum except during exposures.
- Fasting period: during exposures: feed and water were withheld during exposures.
- Water (e.g. ad libitum): water (Municipal Authority of Westmoreland County, Greensburg, PA) were available ad libitum except during exposures.
- Acclimation period: quarantined for approximately 2 weeks, during which time representative animals were subjected to fecal sampling, aerobic bacteriologic cultures of lung tissue, histologic examination of selected organs, and to serum viral antibody evaluation. Quality control data indicated that these animals were in good health and suitable for use. During acclimation, the rats were housed separately by sex, 2–3 per cage, in stainless steel wire mesh cages (6 * 9 * 7 in. high).

ENVIRONMENTAL CONDITIONS
- Temperature: 62–76°F; room temperature was recorded continuously (Cole-Parmer Hygrothermograph Seven-Day Continuous Recorder, Model No. 8368–00, Cole-Parmer Instrument Company, Chicago, IL).
- Humidity (%): 40–70% , relative humidity was recorded continuously (Cole-Parmer Hygrothermograph Seven-Day Continuous Recorder, Model No. 8368–00, Cole-Parmer Instrument Company, Chicago, IL).
- Photoperiod (hrs dark / hrs light): 12-h, 0530–1750 h for light phase.

All animals were handled and treated at all times in conformance with the National Institutes of Health Guide (NIH, 1985).
Route of administration:
inhalation: vapour
Type of inhalation exposure (if applicable):
whole body
Vehicle:
air
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Liquid toluene diisocyanate was metered from a syringe pump (Sage Instruments, Cambridge, MA) into a heated glass evaporator, similar in design to that described by Carpenter et al. (1975).
The resultant vapour was carried into the chamber by a counter-current air stream that entered the bottom of the evaporator. Chamber atmospheres containing toluene diisocyanate were filtered before leaving an exhaust stack.
The four chambers employed in this study were rectangular in shape, constructed of glass and stainless steel (Wahmann Manufacturing Company, Timonium, MD), and measured approximately 2.1m * 1m * 2.1m (height). Total volume in each chamber was approximately 4320 L. An orifice plate was positioned in the exhaust duct of the chamber and was connected to a Dwyer Magnehelic Pressure Gauge. Airflow in each chamber was approximately 1000–1500 L/min (at least 14 air changes per h), with a t99 (theoretically derived time required for the chamber to reach 99% of the equilibrium concentration) of approximately 20 min. The chambers were illuminated with artificial room light. Within each chamber, the animal cages were rotated daily to compensate for any possible but undetected variation in chamber exposure conditions (i.e., concentration, temperature, relative humidity). A vapour distribution study involving six sampling positions each at 0.02 and 1.0 ppm indicated low coefficients of variation (3.0–7.4%) and, therefore, uniform distribution of toluene diisocyanate vapor within the range of target exposure concentrations employed.
- Method of holding animals in test chamber:
- Source and rate of air:
- Method of conditioning air:
- System of generating particulates/aerosols:
- Temperature, humidity, pressure in air chamber: The temperature in the evaporator was monitored and maintained at the lowest level sufficient to vaporize the liquid (46–60°C). Temperature (Minimum-Maximum Thermometer, Abbeon Cal, Inc., Santa Barbara, CA, or Brooklyn Thermometer Co., Inc., Farmingdale, NY) and relative humidity (Airguide Instrument Company, Chicago, IL) gauges were placed inside each chamber during exposures. Chamber temperature, relative humidity, and air- flow rate were recorded every 30 min during each 6-h exposure.
- Air flow rate:
- Air change rate:
- Method of particle size determination:
- Treatment of exhaust air:

TEST ATMOSPHERE
- Brief description of analytical method used: Two Autostep Portable Monitors (GMD Systems, Inc., Hendersonville, PA) were used to monitor the TDI concentration in the exposure chamber atmospheres. The Model 920 isocyanates instrument (0–0.2 ppm range) was used to measure the concentrations in the atmospheres of the control, the 0.02, and 0.1 ppm exposure chambers. A second instrument was specially constructed by the manufacturer to monitor the higher TDI concentrations of the 0.5 ppm target exposure chamber atmosphere.
Both instruments operated using the same basic principles. A volume of air was drawn through a chemically impregnated paper tape. A stain developed on the tape with an intensity proportional to the TDI concentration. The sensitivity to the 2,4- and 2,6-isomers was the same.
The GMD instruments were calibrated prior to exposure using the Marcali method, as modified by Rando and Hammad (1985).
The impinger samples were then analysed by the modified Marcali method, and the results were compared. Correction factors were calculated for the instruments, so that the corrected instrument results agreed with the modified Marcali results.
For analysis of TDI by the modified Marcali method, chamber atmosphere samples were drawn through two midget impingers (in series) using Reciprotor (Waltham Chemical Pump Corporation) pumps equipped with critical orifices.
Impinger efficiencies were 95%, and results were corrected accordingly. The impinger solution was 15 ml of 2.2% acetic acid, 3.5% hydrochloric acid in water. This solution was used to hydrolyze the TDI to its corresponding diamine. The samples were then cooled to 0°C in an icewater bath. A 0.5-ml aliquot (cooled) of 3% sodium nitrite, 5% sodium bromide in water was then added to the sample. These solutions were mixed rapidly using a vortex mixer and then allowed to react for 0.5 min. This reaction diotized the toluene diamine to a diazonium compound. One mL of 10% sulfamic acid was then added to destroy excess nitrous acid. One milliliter of 0.1% naphthylethylenediamine was added. A coloured complex formed. The sample was diluted to 25.0 ml with distilled water and the absorbance measured at 548 nm with a Bausch and Lomb Spectronic 710 UV-Visible Optical Spectrometer.
- Samples taken from breathing zone: yes - Instrument measurements and impinger samples were taken from each of the chamber atmospheres.
A soap film buret (24°C, 735 mm Hg) was used to determine the 1 l/min flowrates of the sampling systems. Sampling times were typically 20, 10, and 6 min for the low, mid, and high concentration atmospheres, respectively.
Each chamber atmosphere was analysed for toluene diisocyanate approximately six times during each 6-h exposure. Daily nominal concentrations (an estimated concentration calculated from the amount of test material delivered and the chamber airflow during the exposure period) were also calculated for each chamber.

For exposures, plug-positive females were transferred to stainless steel wire mesh exposure cages (35 cm x 17 cm x 18 cm high) in cage carriers that were moved onto the chambers. Feed and water were withheld during exposures. Exposures were for 6 h/day, gd 6–15. After each exposure, animals were returned to their original cages and “home” room. The animals were observed daily for clinical signs throughout the study (gd 0–21). Maternal body weights were taken on gd 0, 6, 9, 12, 16, and 21. Maternal feed and water consumption was measured at 3-day intervals, gd 0–3, 3–6, 6–9, 9–12, 12–15, 15–18, and 18–21.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Chamber Analyses
The mean analytical concentrations for the 0.02, 0.10, and 0.50 ppm (0.14, 0.72, and 3.6 mg/m³) chambers were 0.021 +/- 0.0018 ppm (105.0% of target), 0.12 +/- 0.017 ppm (120.0% of target), and 0.48 +/- 0.038 ppm (96.0% of target), respectively. No test chemical was detected in the control chamber (0 ppm) with a minimum detection limit of 1 ppb. The analytical to nominal concentration ratios were 0.44–0.72. Mean temperature was maintained at 22.6 –23.9°C and mean relative humidity at 50.1–54.4% for all four chambers.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused: housed in stainless steel wire mesh cages and the paperboard beneath the cages
- M/F ratio per cage: 1:1 (one male:one female)
- Length of cohabitation:
- After ... days of unsuccessful pairing replacement of first male by another male with proven fertility.
- Further matings after two unsuccessful attempts: [no / yes (explain)]
- Verification of same strain and source of both sexes: [yes / no (explain)]
- Proof of pregnancy: checked twice daily for dropped copulation plugs. The date a copulation plug was found was designated gd 0 (Hafez, 1970).
- Any other deviations from standard protocol:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: one male:one female in stainless steel wire mesh cages and the paperboard beneath the cages checked twice daily for dropped copulation plugs
- Length of cohabitation:
- After ... days of unsuccessful pairing replacement of first male by another male with proven fertility.
- Further matings after two unsuccessful attempts: [no / yes (explain)]
- Verification of same strain and source of both sexes: [yes / no (explain)]
- Proof of pregnancy: copulation plug referred to as day 0 of pregnancy
- Any other deviations from standard protocol:
Twenty-five mated females were assigned to each experimental group on gd 0 by stratified randomization procedures based on body weight.
Duration of treatment / exposure:
6 h/day
Frequency of treatment:
once daily
Duration of test:
gd 6–15, observation period gd 0 - 21
Remarks:
Doses / Concentrations:
0.0 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0.02 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0.1 ppm
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0.5 ppm
Basis:
nominal conc.
No. of animals per sex per dose:
25 mated females
Control animals:
not specified
Details on study design:
- Dose selection rationale: To determine appropriate target concentrations of TDI for the definitive study, a range-finding study was performed following the same study design as in the definitive study, except that eight inseminated females per group were employed, the exposure concentrations were 0.0, 0.1, 0.5, and 1.0 ppm (analytical concentrations 0.0 [minimum detection limit of 1 ppb], 0.12 +/- 0.013, 0.48 +/- 0.018, and 0.95 +/- 0.093 ppm), and the dams were terminated after the last exposure on gd 15. At termination, immediately after the last exposure, the dams were anesthetized with methoxyflurane (Metofanet, Pittman-Moore) and arterial blood was removed from the abdominal aorta into arterial blood samplers (Carney Medical, Medfield, MA) containing heparin as an anticoagulant. Blood parameters directly measured were pH, pCO2 and pO2 (Corning Model 170 Blood Gas Analyzer, Corning Medical, Medfield, MA); HCO3- (bicarbonate) was calculated by the following formula: 0.031 pCO2 X 10E(pH–6.1). Commercially available quality control samples (Certain, Level I, II, III, Corning Medical, Medfield, MA) were analysed prior to and following every 10 samples, with appropriate calibration checks immediately prior to sample analysis. The dams were then examined for body weight, gravid uterine weight, liver weight, number of ovarian corpora lutea, number of uterine implantation sites (total, early, and late absorptions, and dead implants [there were none]), and live implants. At 1.0 ppm, maternal body weights, weight changes, and liver weights (absolute but not relative) were profoundly and significantly reduced, audible respiration and nasal red discharge were observed; stomach and intestines were gas filled (due to gasping), and adrenal glands were enlarged (most likely due to stress). There were no effects of treatment on any gestational parameters, including pre- or postimplantation loss and percent live implants per litter at any exposure concentration tested. The maternal blood gas results include the following statistically significant changes at 1.0 ppm: reduced pH (1%), markedly increased pCO2 (31%), markedly decreased pO2 (33%), and slightly increased HCO3- (13%). These alterations are characteristic of respiratory acidosis resulting from compromised pulmonary function. Typically, as a result of impaired alveolar ventilation, arterial O2 levels are reduced, CO2 is inefficiently eliminated, and the bicarbonate levels rise to compensate for the increased CO2 levels. (Based on the slight increase in bicarbonate and the effects on pH, pCO2 and pO2, compensation was apparently not achieved.) Since this compensating change takes place over 2–3 days, the alterations are considered to be of a chronic nature. (The use of methoxyflurane as an anaesthetic may have confounded the blood gas results, as the pH of conscious control rats is usually 7.5 and the mean pH of the anaesthetized control rats in this study was 7.38.) Based on these results, 1.0 ppm was deemed too toxic for use in the definitive study. The target exposure concentrations for definitive study were, therefore, 0.00, 0.02, 0.10, and 0.50 ppm.
- Rationale for animal assignment (if not random): random, each animal was assigned a unique number and received a stainless steel Monelt ear tag (Gey Band and Tag Co., Morristown, PA).
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: The animals were observed daily for clinical signs throughout the study (gd 0–21).

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: The animals were observed daily for clinical signs throughout the study (gd 0–21).

BODY WEIGHT: Yes
- Time schedule for examinations: Maternal body weights were taken on gd 0, 6, 9, 12, 16, and 21.

FOOD CONSUMPTION: Yes
- Maternal feed and water consumption was measured at 3-day intervals, gd 0–3, 3–6, 6–9, 9–12, 12–15, 15–18, and 18–21.

WATER CONSUMPTION: Yes
- Time schedule for examinations: Maternal feed and water consumption was measured at 3-day intervals, gd 0–3, 3–6, 6–9, 9–12, 12–15, 15–18, and 18–21.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21 by carbon dioxide asphyxiation
- Organs examined: The gravid uterus, ovaries (including corpora lutea), cervix, vagina, and abdominal and thoracic cavities were examined grossly. Ovarian corpora lutea of pregnancy were counted, and maternal liver and uterine weights were determined. Sections of maternal liver, kidney(s), and upper and lower respiratory tract (including nasal turbinates) were retained in fixative for possible subsequent histologic examination. The uteri were immediately ligated at their cervical end to prevent the expulsion of conceptuses by myo- metrial peristalsis, externally examined for signs of haemorrhage, removed from the peritoneal cavity, and dissected longitudinally to expose their contents. All live and dead fetuses and resorption sites (early and late) were noted and recorded. Uteri from females that appeared nongravid were placed in a 10% ammonium sulfide solution for detection of early resorptions (Salewski, 1964).
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
Fetal examinations:
A total of 21–23 litters were examined in each experimental group.

- External examinations: Yes: all live fetuses
- Soft tissue examinations: Yes: 1/2 in each litter was examined for thoracic and abdominal visceral abnormalities
- Skeletal examinations: Yes: 1/2 per litter (the other half)
- Head examinations: Yes: 1/2 per litter (those examined for thoracic and abdominal visceral abnormalities)

All live fetuses were anesthetized by hypothermia and were weighed, sexed, and examined for external malformations, including cleft palate and variations. Approximately one-half of the live fetuses in each litter (even numbered fetuses from litters with an even number of live fetuses; odd numbered fetuses from litters with an odd number of live fetuses) were examined for thoracic and abdominal visceral abnormalities by modification of methods described by Staples (1974). The fetuses examined viscerally were decapitated and their heads were fixed in Bouin’s solution for examination of craniofacial structures by serial freehand sectioning methods modified from Wilson (1965; 1973) and van Julsingha and Bennett (1977). Intact fetuses (not decapitated) in each litter were eviscerated, fixed in ethanol, then processed for skeletal staining with alizarin red S (Crary, 1962; Peltzer and Schardein, 1966) and examined for ossified skeletal malformations and variations. Decapitated fetuses were also processed for skeletal staining but were not examined.
Statistics:
The unit of comparison was the pregnant dam or the litter (Weil, 1970). Results of the quantitative continuous variables (e.g., maternal body weights, liver weights, etc.) were intercompared for the three exposure groups and control group by use of Levene’s test for equal variances (Levene, 1960), analysis of variance (ANOVA), and t-tests with Bonferroni probabilities. The t-tests were used when the F value from the ANOVA was significant. When Levene’s test indicated homogeneous variances, and the ANOVA was significant, the pooled t-test was used for pairwise comparisons. When Levene’s test indicated heterogeneous variances, all groups were compared by an ANOVA for unequal variances (Brown and Forsythe, 1974), followed when necessary by the separate variance t-test for pairwise comparisons. Nonparametric data obtained following necropsy were statistically treated using the Kruskal-Wallis test (Sokal and Rohlf, 1969), followed by the Mann- Whitney U test (Sokal and Rohlf, 1969) when appropriate. Incidence data were compared using Fisher’s Exact Test (Sokal and Rohlf, 1969). For all statistical tests, the fiducial limit of 0.05 (two-tailed) was used as the criterion for significance.
Details on maternal toxic effects:
Maternal toxic effects:yes. Remark: No females died, delivered early, aborted or were removed from study. Reduced Body weight gain, Clinical symptoms: audible respiration and red nasal discharge, reduced feed consumption.

Details on maternal toxic effects:
No females died, delivered early, aborted or were removed from study. Pregnancy rate was equivalent across all groups (84–92%), and all pregnant animals bore at least one live fetus at scheduled sacrifice, except for one dam with a fully resorbed litter at 0.02 ppm.
Body weights and weight gain were equivalent across all groups prior to the start of exposures, gd 0–6. Maternal body weight was significantly reduced at 0.50 ppm, only on gd 16, and at 0.02 ppm only on gd 21 (due at least partially to one fully resorbed litter at 0.02 ppm). Maternal weight gain was statistically reduced early in the exposure period, gd 6–9, at 0.02, 0.10, and 0.50 ppm. At 0.50 ppm, it was also reduced for gd 9–12, 12–16, and 6–16 (exposure period). In addition, weight gain was significantly reduced at 0.02 ppm for gd 16–21 (postexposure period) and for gd 0–21 (gestation period), again due, at least partially, to the one fully resorbed litter at this exposure concentration. Treatment-related clinical signs of toxicity were limited to audible respiration in 15 dams of 23 at 0.50 ppm, and red nasal discharge at 0.02 ppm (five dams), 0.10 ppm (three dams), and 0.50 ppm (seven dams during the exposure period). The latter sign did not exhibit a concentration-related incidence, but it was observed only in toluene diisocyanate-exposed dams during the exposure period; in the postexposure period (gd 16–21), the incidence was 1, 1, 2, and 6 dams at 0.0, 0.02, 0.10, and 0.50 ppm, respectively. Maternal feed consumption was significantly reduced at 0.50 ppm for gd 9–12 and 12–15, and for gd 6–15 (exposure period). In addition, feed consumption was reduced at 0.02 ppm for gd 18–21 (in the postexposure period), possibly due to the dam with one fully resorbed litter (eating at a nonpregnant rate) and smaller litter sizes in this group. Maternal water consumption exhibited no statistically significant differences among groups for any interval measured, gd 0–21. Maternal gross observations at necropsy indicated no treatment-related lesions. Maternal body weight at sacrifice was statistically reduced at 0.02 ppm, again most likely related to the one dam in this group with a fully resorbed litter and smaller litter sizes. Gravid uterine weights, body weights at sacrifice corrected for gravid uterine weight, and body weight change (gestational weight gain corrected for the weight of the gravid uterus) were unaffected by treatment, as was absolute or relative liver weight.

The maternal toxicity at 0.50 ppm included reduced maternal weight gain and feed consumption, and clinical signs of toxicity, all observed during the exposure period. Clinical signs were limited to audible respiration exclusively at 0.50 ppm during exposures, and red nasal discharge observed predominantly at 0.50 ppm during and after the exposure period (with no dose–response pattern at 0.02 and 0.10 ppm during exposure and at low incidence; one to two dams at these exposure concentrations in the postexposure period). Concentration-related reduced body weight gains were also observed for all TDI-exposed groups for the first exposure interval, gd 6–9. However, at 0.02 and 0.10 ppm, these effects were clearly transient (and less extreme, p , 0.05, versus the effect at 0.50 ppm, p , 0.001), with no significant effects occurring at 0.02 or 0.10 ppm for subsequent treatment intervals, gd 9–12 or gd 12–16, or for the entire exposure period, gd 6–16.
Dose descriptor:
NOAEL
Effect level:
0.1 ppm
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEL
Effect level:
0.1 ppm
Based on:
test mat.
Basis for effect level:
other: developmental toxicity
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes. Remark: reduced number of total implants per litter and of viable implants per litter at 0.02 ppm; one poorly ossified cervical centrum 5, exhibited an increased incidence at 0.50 ppm relative to that in controls, indicative of possible minimal fetotoxicity.

Details on embryotoxic / teratogenic effects:
The number of corpora lutea per dam was unaffected by treatment. The number of total implants per litter was reduced at 0.02 ppm, and the number of viable implants per litter was also reduced at 0.02 ppm, probably because of the reduced implant count (as preimplantation loss was not significantly affected by treatment), and because of one fully resorbed litter at 0.02 ppm. The number of nonviable implants per litter (total, early or late resorptions, or dead fetuses) and the percent live fetuses per litter were not significantly changed by treatment. Sex ratio (% males) per litter was unchanged by exposures. Fetal body weight per litter (males, females, or all fetuses) was unaffected by exposure.
There were no significant differences in the incidence of any individual malformation, of malformations by category (external, visceral, or skeletal), or of total malformations. There were no significant differences in the incidence of individual external or visceral variations, of variations by category, or of total variations. Out of 111 skeletal variations observed in the present study, six exhibited statistically significant differences in incidence in one or more toluene diisocyanate-exposed groups relative to the incidence in the control group. Only one of these, poorly ossified cervical centrum 5, exhibited an increased incidence at 0.50 ppm relative to that in controls, indicative of possible minimal fetotoxicity. This finding was observed in the absence of any other indication of developmental toxicity. The five remaining significant findings did not indicate fetotoxicity and did not appear treatment related. They included reductions in the incidence of bilobed thoracic centra 11 and 13 and wavy rib at 0.50 ppm, and reductions in the incidence of some (1– 4) proximal phalanges of the forelimb unossified and of all proximal phalanges of the hindlimb unossified at 0.02 ppm.
Abnormalities:
not specified
Developmental effects observed:
not specified
Table 2: Chamber analysis
Exposure Parameters        
Target Concentration, ppm 0.00 0.02 0.10 0.50
Analytical Concentration, ppm a  < MDL b 0.021 ±0.0018 0.12 ± 0.017 0.48 ± 0.038
A/T Ratio c  -   1.05  1.20  0.96
 Nominal Concentration, ppm a  -  0.049 ± 0.0038  0.18 ± 0.017   0.67 ± 0.025
 A/N Ratio d  -   0.44  0.67  0.72 
 Temperature, °C a 22.6 ± 0.43 23.3 ± 0.44  23.5 ± 0.33 23.9 ± 0.19
Relative Humidity, %a  54.4 ± 0.86  50.9 ± 1.65  52.1 ± 0.98  50.1 ± 1.41
aGrand mean of daily means ± standard deviation.
bLess than the minimum detection limit of 1 ppb.
cAnalytical to target concentration ratio.
dAnalytical to nominal concentration ratio.

Table 3:  Maternal Toxicity Parameters       
   TDI vapour, ppm
0.00 0.02 0.10 0.50
No. females on study 25 25 25 25
No. females at scheduled sacrificea 25 (100.0) 25 (100.0) 25 (100.0) 25 (100.0)
No. (%) gravid 22 (88.0) 21 (84.0) 23 (92.0) 23 (92.0)
No. (%) fully resorbed litters 0 (0.0) 1 (4.8) 0 (0.0) 0 (0.0)
No. (%) dams with viable fetuses 22 (100.0) 20 (95.2) 23 (100.0) 23 (100.0)
Maternal Body Weight Changes        
Day 0 to 6 (pre-exposure period) 36.1±8.05b 33.3 ± 7.98 33.7 ± 8.43 40.1 ± 8.29
Day 6 to 9 12.3 ± 3.90 9.2±3.76* 9.4 ± 2.89* 1.8 ± 5.31***
Day 9 to 12 16.7 ± 4.35 16.9 ± 4.74 17.7 ± 4.95 11.3 ± 8.23*
Day 12 to 16 24.1 ± 4.88 20.8 ± 7.10 22.5 ± 6.03 15.8 ± 8.23*
Day 6 to 16 (exposure period) 53.1 ± 7.37 46.4 ± 11.66 49.5 ± 9.96 28.9 ± 17.59***
Day 16 to 21 (post exposure period) 89.1 ± 11.63 76.3 ± 18.67* 88.4 ± 13.23 95.3 ± 18.07
Day 0 to 21 (gestation) 178.3 ± 20.25 156.0 ± 32.02* 171.5 ± 18.42 164.4 ± 28.79
Maternal Feed Consumption (g/animal/day)        
Day 0 to 6 (pre-exposure period) 22.91± 3.434b 21.44 ± 2.909 22.37 ± 4.045 22.28 ± 2.129
Day 6 to 15 (exposure period) 23.10±2.524 22.69 ± 2.123 23.17 ± 2.481 19.62 ± 2.006***
Day 15 to 21 (post exposure period) 26.64 ± 2.537 25.22 ± 2.009 26.60 ± 2.801 25.48 ± 3.267
Maternal Water Consumption (g/animal/day)        
Day 0 to 6 (pre-exposure period) 36.45±7.331b 34.88 ± 8.247 38.71 ± 12.623 41.67 ± 11.249
Day 6 to 15 (exposure period) 43.71 ± 9.743 42.03 ± 9.802 42.77 ± 11.509 39.14±10.374
Day 15 to 21 (post exposure period) 51.71 ± 8.897 54.91 ± 15.653 51.80±11.350 52.39 ± 11.772
aNo females died, aborted, delivered early, or were removed from study.         
bData are presented as mean ± SD.            
*p < 0.05 compared to control.            
**p < 0.01 compared to control.            
***p < 0.001 compared to control.            

Table 4: Maternal Organ Weights
   TDI Vapour, ppm        
  0.00 0.02 0.10 0.50
No. Dams 22 217 23 23
 Initial body weight (g)  223.08 ± 10.89a 220.65 ± 10.58  222.30 ± 9.05  224.16 ± 7.97
Body weight at sacrifice (g)  401.43 ± 24.34  376.63 ± 34.45*   393.80 ± 20.77   388.53 ± 31.40
Gravid uterine weight (g) 106.68 ± 12.22  92.50 ± 28.19  101.31 ± 18.21   101.25 ± 22.40 
 Corrected body weight (g)b  294.74 ± 19.25  284.14 ± 16.41 292.49 ± 15.81 287.28 ± 21.82 
Corrected body weight change (g)c 71.66 ± 14.11   63.49 ± 14.55   70.20 ± 12.43 63.12 ± 17.90 
 Liver weight (g) 14.35 ± 1.58  13.34 ± 2.80  14.33 ± 1.37  13.98 ± 1.53 
 Relative liver weight (%)d 4.86 ± 0.39  4.70 ± 0.5 4.90 ± 0.39 4.87 ± 0.48
aData are presented as mean ± SD.
bCorrected body weight = body weight at sacrifice minus gravid uterine weight.
cCorrected body weight change = corrected body weight minus initial body weight.
dCalculated as a percentage of the corrected body weight.
*p < 0.05 compared to control.

Table 5: Gestational Parameters
   TDI Vapour, ppm     
  0.00 0.02 0.10 0.50
No. dams 22 21 23 23
Corpora lutea/dam 17.4±3.8a 17.6±5.6 17.1±3.6 16.3±2.8
Total implants/litter 15.3±1.8 13.0±3.8* 14.3±3.0 14.3±3.4
% preimplantation loss/litterb 10.2±14.0 18.6±19.0 14.6±18.8 12.1±19.01
Viable implants/litter 14.5±1.7 12.3±4.0* 13.5±2.8 14.0±3.5
Non-viable implants/litter 0.7±0.9 0.7±1.1 0.8±1.1 0.3±0.5
Early resorptions/litter 0.6±0.7 0.6±0.9 0.7±1.0 0.3±0.5
Late resorptions/litter 0.1±0.3 0.1±0.3 0.1±0.4 0.0±0.0
Dead fetuses/litter 0.0±0.0 0.0±0.0 0.0±0.2 0.0±0.0
% live fetuses/litter 95.4±5.4 89.1±23.6 94.6±6.7 97.1±5.7
No. litters 22 20c 23 23
Sex ratio (% male fetuses)/litter 49.8±12.6 44.4±15.6 54.6±16.1 46.2±14.1
Fetal body weights per litter (g)        
All fetuses 5.21±0.21 5.37±0.25 5.37±0.30 5.22±0.37
Male fetuses 5.32±0.23 5.51±0.37 5.51±0.36 5.37±0.39
Female fetuses 5.10±0.21 5.27±0.38 5.20±0.28 5.09±0.36
aData are presented as mean±SD.
bPercent preimplantation loss=[(corpora lutea - total implants)/corpora lutea]*100.
cThe N is reduced because one dam was found to be pregnant by ammonium sulfide staining of the uterus (i.e., a fully resorbed litter).
*p<0.05compared to control.

Table 6: Summarized Incidence and Frequency of Fetal Malformations and Variations
   TDI vapour, ppm     
0.00 0.02 0.10 0.50
Number examined externallya        
Fetuses 320 258 311 322
Litters 22 20 23 23
No significant malformation findings        
Number examined viscerally'b        
Fetuses 164 134 162 168
Litters 22 20 23 23
No significant malformation findings        
Number examined skeletallyc        
Fetuses 156 124 149 154
Litters 22 20 23 23
No significant malformation findings        
Significant variations        
Cervical centrum no. 5 poorly ossified        
No. (%) fetuses 13 (8.3) 18 (14.5) 29 (19.5) 36 (23.4)
No. (%) litters 8 (36.4) 12 (60.0) 14 (60.9) 18 (78.3)*
Wavy rib        
No. (%) fetuses 45 (28.8) 27 (21.8) 16 (10.7) 11 (7.1)
No. (%) litters 11 (50.0) 9 (45.0) 8 (34.8) 4 (17.4)*
All proximal phalanges (hindlimb) unossified        
No. (%) fetuses 61 (39.1) 23 (18.5) 57 (38.3) 58 (37.7)
No. (%) litters 19 (86.4) 9 (45.0)* 18 (78.3) 20 (87.0)
Summarized malformations        
External        
No. (%) fetuses 0 (0.0) 1 (0.4)d 0 (0.0) 0 (0.0)
No. (%) litters 0 (0.0) 1 (5.0) 0 (0.0) 0 (0.0)
Visceral        
No. (%) fetuses 7 (4.3) 7 (5.2) 9 (5.6) 8 (4.8)
No. (%) litters 5 (22.7) 5 (25.0) 6(26.1) 7 (30.4)
Skeletal        
No. (%) fetuses 1 (0.7) 3 (2.4) 2(1.3) 1 (0.6)
No. (%) litters 1 (4.5) 3 (15.0) 2 (8.7) 1 (4.3)
Total malformations        
No. (%) fetuses 8 (2.5) 10 (3.9) 11 (3.5) 9 (2.8)
No. (%) litters 6 (27.3) 7 (35.0) 8 (34.8) 8 (34.8)
Summarized variations        
External        
No. (%) fetuses 16 (5.0) 10 (3.9) 9 (2.9) 12 (3.7)
No. (%) litters 13 (59.1) 7 (35.0) 7 (30.4) 10 (43.5)
Visceral        
No. (%) fetuses 106 (64.6) 93 (69.4) 99 (61.1) 86 (51.2)
No. (%) litters 20 (90.9) 20 (100.0) 22 (95.7) 22 (95.7)
Skeletal        
No. (%) fetuses 156 (100.0) 124 (100.0) 149 (100.0) 154 (100.0)
No. (%) litters 22 (100.0) 20 (100.0) 23 (100.0) 23 (100.0)
Total variations        
No. (%) fetuses 265 (82.8) 220 (85.3) 249 (80.1) 243 (75.5)
No. (%) litters 22 (100.0) 20 (100.0) 23 (100.0) 23 (100.0)
Note: A single fetus may be represented more than once in listing individual defects. Only live fetuses were examined.
aAll fetuses were examined externally.
bApproximately 50% of each litter were examined viscerally (Staples, 1974) and for soft tissue craniofacial defects (Wilson, 1965; van Julsingha and Bennett, 1977).
cApproximately 50% of each litter were examined for skeletal defects after staining with alizarin red S.
dOne fetus (in one litter) at 0.02 ppm exhibited multiple malformations and variations; all four of the external malformations observed (unilateral anophthalmia, cleft palate, unilateral microtia, parasitic twin on ventrum), and 11 of the 24 visceral malformations observed (it was not randomly selected for skeletal examination).
*p< 0.05 compared to control.
Conclusions:
The study on toluene diisocyanate was performed according to EPA OTS 789.4350 (Inhalation Developmental Toxicity Screen), it is considered to be of high quality (reliability Klimisch 2). The criteria of validity of the test system are fulfilled. There was only one possible indication of minor fetotoxicity at 0.50 ppm with no other indications of developmental toxicity.The NOAEL for maternal and developmental toxicity was 0.1 ppm in this study. No embrytoxicity or teratogenicity was observed at any exposure concentrations employed.
Executive summary:

The developmental toxicity of toluene diisocyanate was investigated in Sprague Dawley rats according to EPA OTS 798.4350 (Inhalation Developmental Toxicity Screen) (Tyl, 1999). The test substance was administered to mated female rats via inhalation (0, 0.02, 0.1 or 0.5 ppm, 6 h/day, from gestation day 6 to 15). Maternal clinical signs, body weights, and feed and water consumption were recorded throughout gestation. At termination (gd 21), maternal body, gravid uterine, and liver weights were recorded. Corpora lutea were counted, and implantation sites were identified. In addition resorptions and dead and live fetuses were recorded. All live fetuses were examined for external alterations. One-half of the live fetuses/litter were examined for visceral (including craniofacial) alterations. The remaining intact fetuses/litter were stained with alizarin red S and examined for ossified skeletal alterations. The most plausible and appropriate interpretation of the initial, brief, minor, and transient decrements in weight gain at 0.02 and 0.10 ppm is that they were due to initial responses of the dams as they acclimated to exposure of an irritating vapour rather than to toxicity per se. There were also significant reductions at 0.02 ppm in maternal weight gain for gd 16–21 (p < 0.05; postexposure period), therefore, for gd 0–21 (p < 0.05, gestational period) and for body weight at sacrifice (p < 0.05; not observed at 0.10 or 0.50 ppm), accompanied by significant reductions in total implants per litter and in viable implants per litter (both p < 0.05) at 0.02 ppm. These effects at 0.02 ppm were due, at least partially, to the presence of a fully resorbed litter with one implant only in this group (the dam and her data were included in the summary tables because she was pregnant). When her data are deleted from the individual data and the revised data statistically compared to the control group values for gd 21 terminal body weight and viable implants per litter, the differences were still statistically significant but less so. It is unlikely that this cluster of interrelated effects is due to exposure to TDI for the following reasons: (1) none of the effects were observed at higher concentrations so it is not dose related; (2) the major effect, reduced body weight gain for gd 16–21, occurred after exposures were over (they ended on gd 15); (3) this last trimester is during the time of rapid fetal growth and weight gain, and so the reduced maternal weight gain was most likely due to the reduced number of fetuses per litter in this group (i.e., the fetuses grew normally but were fewer in number); and (4) the reduction in maternal weight gain for gd 16–21 for 0.02 ppm was enough to affect the gestational weight gain (gd 0–21) for maternal body weight on gd 21 but did not affect maternal weight gain during the exposure period (gd 6–16). The cause of the smaller litters at 0.02 ppm is most likely due to biologic variation, with the viable litter size (12.9) slightly below the current historical control values of 13.30 –16.24 live fetuses per litter. The maternal toxicity at 0.50 ppm consisted of reduced body weights, body weight gains, feed consumption, and clinical signs of toxicity. Water consumption was unaffected. Gestational parameters exhibited no significant treatment-related changes, including pre- and postimplantation loss, sex ratio/litter, or fetal body weights/litter. Incidences of individual malformations, malformations by category (external, visceral, and skeletal), total malformations, individual external and visceral variations, variations by category, and total variations were unaffected. Of 111 skeletal variants observed, only 1, incidence of poorly ossified cervical centrum 5, was increased at 0.50 ppm, indicating possible minimal fetotoxicity, although it occurred in the absence of any other indications of developmental toxicity. Therefore, exposure to TDI vapor by inhalation, during major organogenesis in CD rats, resulted in maternal toxicity and minimal fetotoxicity at 0.50 ppm. No treatment-related embryotoxicity or teratogenicity was observed. The A/D ratio (Fabro et al., 1982), the ratio of the lowest doses resulting in adult and developmental toxicity, is at most 1.0, indicating no preferential susceptibility to the conceptus.

This study confirmed effects of TDI on the maternal respiratory tract, with concomitant reductions in maternal body weight, weight gain, and feed consumption at 0.50 ppm. There was only one indication of possible minor fetotoxicity at 0.50 ppm (increased incidence of reduced ossification in cervical centrum no. 5), with no other indications of developmental toxicity. There was no evidence of maternal or developmental toxicity at 0.02 or 0.10 ppm, and no evidence of embryotoxicity or teratogenicity at any exposure concentration evaluated. The present study has shown that exposure to toluene diisocyanate vapour by inhalation during major organogenesis in CD (Sprague-Dawley) rats results in maternal toxicity and minimal indication of fetotoxicity at 0.50 ppm. The no observable adverse effect level (NOAEL) for maternal and developmental toxicity was 0.10 ppm in this study. No embryotoxicity or teratogenicity was observed at any exposure concentrations employed.

 

Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEC
1.2 mg/m³
Study duration:
subchronic
Species:
rat
Quality of whole database:
well-documented study, which meets basic scientific principles
Additional information

The developmental toxicity of toluene diisocyanate was investigated in Sprague Dawley rats according to EPA OTS 798.4350 (Inhalation Developmental Toxicity Screen) (Tyl, 1999). The test substance was administered to mated female rats via inhalation (0, 0.02, 0.1 or 0.5 ppm, 6 h/day, from gestation day 6 to 15). Maternal clinical signs, body weights, and feed and water consumption were recorded throughout gestation. At termination (gestation day 21), maternal body, gravid uterine, and liver weights were recorded. Corpora lutea were counted, and implantation sites were identified. In addition resorptions and dead and live fetuses were recorded. All live fetuses were examined for external alterations. One-half of the live fetuses/litter were examined for visceral (including craniofacial) alterations. The remaining intact fetuses/litter were stained with alizarin red S and examined for ossified skeletal alterations. The most plausible and appropriate interpretation of the initial, brief, minor, and transient decrements in weight gain at 0.02 and 0.10 ppm is that they were due to initial responses of the dams as they acclimated to exposure of an irritating vapour rather than to toxicity per se. There were also significant reductions at 0.02 ppm in maternal weight gain for gestation day 16–21 (p < 0.05; postexposure period), therefore, for gestation day 0–21 (p < 0.05, gestational period) and for body weight at sacrifice (p < 0.05; not observed at 0.10 or 0.50 ppm), accompanied by significant reductions in total implants per litter and in viable implants per litter (both p < 0.05) at 0.02 ppm. These effects at 0.02 ppm were due, at least partially, to the presence of a fully resorbed litter with one implant only in this group (the dam and her data were included in the summary tables because she was pregnant). When her data are deleted from the individual data and the revised data statistically compared to the control group values for gd 21 terminal body weight and viable implants per litter, the differences were still statistically significant but less so. It is unlikely that this cluster of interrelated effects is due to exposure to TDI for the following reasons: (1) none of the effects were observed at higher concentrations so it is not dose related; (2) the major effect, reduced body weight gain for gd 16–21, occurred after exposures were over (they ended on gd 15); (3) this last trimester is during the time of rapid fetal growth and weight gain, and so the reduced maternal weight gain was most likely due to the reduced number of fetuses per litter in this group (i.e., the fetuses grew normally but were fewer in number); and (4) the reduction in maternal weight gain for gd 16–21 for 0.02 ppm was enough to affect the gestational weight gain (gd 0–21) for maternal body weight on gd 21 but did not affect maternal weight gain during the exposure period (gestation day 6–16). The cause of the smaller litters at 0.02 ppm is most likely due to biologic variation, with the viable litter size (12.9) slightly below the current historical control values of 13.30 –16.24 live fetuses per litter. The maternal toxicity at 0.50 ppm consisted of reduced body weights, body weight gains, feed consumption, and clinical signs of toxicity. Water consumption was unaffected. Gestational parameters exhibited no significant treatment-related changes, including pre- and postimplantation loss, sex ratio/litter, or fetal body weights/litter. Incidences of individual malformations, malformations by category (external, visceral, and skeletal), total malformations, individual external and visceral variations, variations by category, and total variations were unaffected. Of 111 skeletal variants observed, only 1, incidence of poorly ossified cervical centrum 5, was increased at 0.50 ppm, indicating possible minimal fetotoxicity, although it occurred in the absence of any other indications of developmental toxicity. Therefore, exposure to TDI vapour by inhalation, during major organogenesis in CD rats, resulted in maternal toxicity and minimal fetotoxicity at 0.50 ppm. No treatment-related embryotoxicity or teratogenicity was observed. The A/D ratio (Fabro et al., 1982), the ratio of the lowest doses resulting in adult and developmental toxicity, is at most 1.0, indicating no preferential susceptibility to the conceptus.

This study confirmed effects of TDI on the maternal respiratory tract, with concomitant reductions in maternal body weight, weight gain, and feed consumption at 0.50 ppm. There was only one indication of possible minor fetotoxicity at 0.50 ppm (increased incidence of reduced ossification in cervical centrum no. 5), with no other indications of developmental toxicity. There was no evidence of maternal or developmental toxicity at 0.02 or 0.10 ppm, and no evidence of embryotoxicity or teratogenicity at any exposure concentration evaluated. The present study has shown that exposure to toluene diisocyanate vapour by inhalation during major organogenesis in CD (Sprague-Dawley) rats results in maternal toxicity and minimal indication of fetotoxicity at 0.50 ppm. The no observable adverse effect level (NOAEL) for maternal and developmental toxicity was 0.10 ppm in this study (corresponds to 1.2 mg/m³ for TRIDI). No embryotoxicity or teratogenicity was observed at any exposure concentrations employed.

Conclusion:

Minor fetotoxicity effects are considered to be secondary effects of treatment which occur only in the presence of significant maternal effects therefore TDI is not toxic to reproduction and not developmental toxicant.


Justification for selection of Effect on developmental toxicity: via inhalation route:
No studies for developmental toxicity are available for TRIDI. Therefore, a subchronic 2-generation study in rats conducted with TDI, the nearest analogue, is used for the DNEL derivation and further risk assessment.

Justification for classification or non-classification

TRIDI as nearest analogue to TDI is not expected to be a reproductive or developmental toxicant since systemic effects in maternal organism will prevail over any possible fetotoxic or developmental effects. The substance does not meet the criteria for classification and labelling in accordance with European regulation (EC) No. 1272/2008.