Registration Dossier

Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2003-10-14 to 2004-11-09
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2004
Report Date:
2004

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)
Deviations:
not specified
Qualifier:
according to
Guideline:
other: 88/302/EEC (1988)
Deviations:
not specified
Qualifier:
according to
Guideline:
other: Japanese MAFF guidelines (2000, amended 2001).
Deviations:
not specified
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
isophorone diisocyanate of Bayer Polymers, batch no. LL48/3-55, purity 99.8 %, sampled 07 Aug 2003

Test animals

Species:
rat
Strain:
Wistar
Details on test animals and environmental conditions:
TEST ORGANISMS
- Source: Hsd Cpb:WU from Harlan-Winkelmann GmbH, Borchen (Germany)
- Age: between 14 and 17 weeks (females)
- Weight at study initiation: 201 - 244 g (females)
- Number of animals: 27 per dose / control group
Housing conditions:
- Room temperature: 22°C+/-2°C;
- humidity: appr. 50%;
- light: 12hours light/dark;
- air change: 10 times per hour;
- animal room was cleaned daily
- nutrition: standard diet Provimi Kliba Maus/Ratte-Haltung-GLP, Art.-No 3883.0.15 (Provimi Kliba SA, 4303 Kaiseraugst, Switzerland) ad libitum
- water: tap water ad libitum

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure (if applicable):
nose only
Vehicle:
other: air
Details on exposure:

Females:
- exposure by inhalation (nose only) daily from day 6 to 19 post coitum for 6 hours between approximately 08:00 and 14:00 CET.

Males:
- not treated (used only for mating)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Doses used in this study were verified by analysis. The analyses of the test atmospheres are described in the analytical report (study no. T 7072620) which is part of the main study. The test atmosphere was determined by high performance liquid chromatography (HPLC) after derivatization of the isocyanate functionality. Samples were taken by using glass powder filled tubes containing nitro-reagent as scavenging agent. For reference/calibration purposes the test compund was used. The precision, accuracy and stability in solvents as well as on the adsorbent used were checked prior to the study. Chamber samples were taken in the vicinity of the breathing zone.
Details on mating procedure:
MATING PROCEDURES: 
Two females and one male were placed in a cage  overnight. If sperm was detected in the vaginal smear taken in the  morning, this day was 
regarded as day 0 of gestation.
Duration of treatment / exposure:
days 6 through 19 post coitum
Frequency of treatment:
6 hours/day, daily
Duration of test:
The femals were subjected to gross pathological examination at the time of cesarian section on day 20 post coitum. The females were sacrificed using cardiotomy under deep carbon dioxide anesthesia.
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/m³ air (nominal)
Remarks:
Control
Dose / conc.:
0.25 mg/m³ air (nominal)
Remarks:
Low dose
Dose / conc.:
1 mg/m³ air (nominal)
Remarks:
Medium dose
Dose / conc.:
4 mg/m³ air (nominal)
Remarks:
High dose
No. of animals per sex per dose:
27 inseminated females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
Sex: female
Duration of test: cesarean section on day 20

Examinations

Maternal examinations:
PARAMETERS ASSESSED DURING STUDY: 
- Mortality: daily on days 0 through 5 and 20, twice daily on days 6  through 19
- Clinical signs: daily on days 0 through 5 and 20, twice daily on days 6  through 19
- Body weight gain: Weighing on days 0 and 6 through 20, correction for  weight of uterus on day 20
- Food consumption: Cumulative on days 3, 6, 9, 12, 15, 18, and 20; water  consumption 3 times/week

Ovaries and uterine content:
- Examination of uterine content: 
Number of corpora lutea, number of  implantations (in females without visible implantation sites after  staining with 10 % ammonium sulfide 
solution), uterine weights,  individual weight and appearance of the placentas, number of early  resorptions (only implantation sites visible), 
number of late resorptions  (fetal or placental remnant visible), number of dead fetuses (i.e.  without signs of life, without maceration), number and sex of live fetuses
Fetal examinations:
- Examination of fetuses: sex, individual weight, external malformations  or other findings deviating from normal, visceral malformations and other   
findings deviating from normal (Wilson technique), findings in abdominal,  pelvic, and thoracic organs as well as skeletal and cartilage findings  
(modified Dawson technique) with the addition of cartilage staining:  evisceration, cartilage staining with alcian blue GX, clearing of the  fetuses 
with diluted potassium hydroxide solution, staining of the  skeletal system with alizarin red S and evaluation of the skeletal system  including 
cartilaginous findings. Every other fetus within a litter was  prepared for either skeletal or visceral evaluation with generally the  first fetus of 
each litter assigned to skeletal analysis. 
Statistics:
STATISTICAL METHODS: 
- Females without implanatation sites were excluded. Skeletal  localizatins with mechanical damage in single fetuses were excluded from  the 
calculation of percentages of affected localizations but reported in  the tables of individual skeletal findings.
- Analysis of variance, and in case of significant results Dunnett's test  for: feed consumption; body weights (incl. gains and corrections);  
uterine weights; number of corpora lutea, of implantations, of live  fetuses (incl. percentages) per female; placental and fetal weights per  female.
- 2 by N Chi(square) test, and in case of significant differences  Fisher's exact test with Bonferroni correction for: fertility and  gestation rate; 
number of implantations per group; number of  preimplantation losses per group; number of postimplantation losses,  early resorptions, late 
resorptions, or dead fetuses per group; number of  live fetuses per group in percent of implantations; number of male or  female fetuses or fetuses  with undeterminable sex per group; number of  fetuses or litters with external, visceral, and skeletal findings; number  of fetuses or litters with 
malformations.
- Kruskal-Wallis test, and in case of significant differences Dunn's test  for: number of preimplantation losses, postimplantation losses, early  
resorptions, late resorptions or dead fetuses per female; number of male  or female fetuses or fetuses with undeterminable sex per female;  
proportin of placental, fetal external, and fetal visceral findings per  female.
- Chi(square) test (correction according to Yates) for: number of 
fetuses  or litters with cartilaginous tissue observations.
Indices:
For external, skeletal and visceral malformations a scheme for classification and an incidence table is described within the study.
Historical control data:
Description of historical control data is part of the study report (annex) for e.g.: vehicles, clinical findings, feed consumption, body weight gain, gross pathological findings, fertility and gestation index, total resorptions, Cesarean section data, placental findings, number of malformations, spontaneous malformations, external and visceral deviations, skeletal findings in fetuses and litters (including cartilaginous findings), incidence of eye malformations in different historical dose groups

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Rough fur occurred in some females of all study groups, including the control group and showed no dose relationship at a dose level up to and including 1 mg/m3 while incidence was increased at the 4 mg/m3 group. Thus causal relation to treatment was assumed for rough fur in the 4 mg/m 3 group. Piloerection was observed in 2 females each of the 0.25 and 4 mg/m3 groups for single days only. Due to lack of dose
relation/time-related consistency toxicological relevance was not assumed for this finding at an exposure level up to and including 4 mg/m3.

Treatment related clinical findings suggestive of upper respiratory tract irritation were evident in the high 4 mg/m3 exposure group and comprised decreased respiratory rate, laboured breathing, reddish encrusted nostrils, serous nasal discharge and breathing sounds after inhalation. These findings were observed during the treatment period either before placing the females in the inhalation exposure restrainers and/or after inhalation.

Findings at the nose (individually differently nose reddish or reddish encrusted, nostrils reddish encrusted) were seen in 2 females of the 0.25 mg/m3 (nos. 2075 and 2154) and 2 females of the 1 mg/m 3 group (nos. 2078 and 2118). Females in the 0.25 mg/m 3 group were only affected on isolated days at the start of inhalation (day 7 and/or 8 p.c.) while females of the 1 mg/m3 group showed similiar effects either at the beginning (day 8 p.c.) and/or at the end of inhalation (day 15 p.c. or 17 to 20 p.c.). The toxicological significance of these subtle clinical changes in the 0.25 mg/m 3 and 1 mg/m 3 exposure groups is questionable and they were likely related to restraint as a time-related exacerbation or consistency of nasal effects was absent. Therefore, based on clinical findings suggestive of (upper) respiratory tract irritation, 1 mg/m 3 was considered to be the NOAEL.
Thus treatment with Isophorondiisocyanat at the 4 mg/m3 exposure level affected the respiratory tract and the fur and comprised decreased respiratory rate, laboured breathing, breathing sounds, reddish encrusted nostrils, serous nasal discharge and rough fur.
Mortality:
no mortality observed
Description (incidence):
No mortality observed.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Body weight loss occurred in all study groups including the control group after start of inhalation (days 6 to 7 p.c.) and was like the decreased feed intake most probably related to the inhalation procedure. However, in the 4 mg/m 3 exposure group body weight loss was more distinct, statistically significant and observed from day 6 to 8 p.c. together with statistically significantly decreased
body weight gain at the end of gestation (days 16 to 17 p.c. and 18 to 19 p.c.). These findings resulted in statistically significantly reduced overall body weight gain during the treatment and gestation period as well as statistically significantly reduced corrected body weight gain. Thus substance relationship was evident for transient body weight loss and impaired body weight gain in the 4 mg/m3 exposure group.
Marginally reduced corrected body weight gain was as well observed in the 1 mg/m 3 exposure group. However, this reduction was only of a marginal degree, not statistically significant and without influence on final body weight and carcass weight, so that toxicological relevance for this observation in the 1 mg/m 3 exposure group was not assumed.

Thus, treatment with Isophorondiisocyanat at the 4 mg/m3 exposure level resulted in transient body weight loss and impaired body weight gain.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Reduced feed intake was observed in all study groups including the control group after start of inhalation (days 6 to 9 p.c.) and was most probably related to the inhalation procedure. Feed intake compared to the control group was statistically significantly reduced during treatment with Isophorondiisocyanat at the 4 mg/m 3 exposure level while effects were not evident at an exposure level up to and including 1 mg/m 3 . Statistically significantly reduced feed consumption in the 0.25 mg/m 3 exposure group at the end of gestation was not dose related and thus considered incidental.

Summarizing the findings treatment with Isophorondiisocyanat at the 4 mg/m 3 exposure level resulted in decreased feed intake.
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
no effects observed
Description (incidence and severity):
Effects on water intake and excretion of urine and feces were not observed at an exposure level up to and including 4 mg/m3.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Gross pathological findings:
no effects observed
Description (incidence and severity):
Necropsy revealed no treatment related gross pathological findings at an exposure level up to and including 4 mg/m3 .
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Details on results:
Maternal toxic effects:yes

Details on maternal toxic effects:
No mortalities were reported. Treatment with the test substance Isophorondiisocyanat (IPDI) at the 4 mg/m3 exposure level affected the respiratory tract and the fur and comprised decreased respiratory rate (bradypnea), laboured breathing, breathing sounds, reddish encrusted nostrils, serous nasal discharge and rough fur. Furthermore, decreased feed intake, body weight loss for 2 days and impaired body weight gain was evident in the 4 mg/m3 exposure group. Necropsy revealed no treatment related gross pathological findings at an exposure level up to and including 4 mg/m3.

Maternal developmental toxicity

Number of abortions:
no effects observed
Description (incidence and severity):
The gestation rate (number of females with viable fetuses as a percentage of the number of females with implantations) was unaffected by treatment with Isophorondiisocyanat at levels up to and including 4 mg/m 3 .
Pre- and post-implantation loss:
no effects observed
Description (incidence and severity):
Mean postimplantation loss and number of live fetuses were unaffected by treatment with Isophorondiisocyanat at an exposure level up to and including 4 mg/m3.
Total litter losses by resorption:
no effects observed
Description (incidence and severity):
Mean postimplantation loss and number of live fetuses were unaffected by treatment with Isophorondiisocyanat at an exposure level up to and including 4 mg/m3.
Early or late resorptions:
no effects observed
Description (incidence and severity):
Mean postimplantation loss and number of live fetuses were unaffected by treatment with Isophorondiisocyanat at an exposure level up to and including 4 mg/m3.
Dead fetuses:
no effects observed
Description (incidence and severity):
Mean postimplantation loss and number of live fetuses were unaffected by treatment with Isophorondiisocyanat at an exposure level up to and including 4 mg/m3.
Changes in pregnancy duration:
not specified
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): not specified
Changes in number of pregnant:
no effects observed
Description (incidence and severity):
Mean postimplantation loss and number of live fetuses were unaffected by treatment with Isophorondiisocyanat at an exposure level up to and including 4 mg/m3.
Details on maternal toxic effects:
With respect to the parameters of intrauterine development, gestation rate, postimplantation loss, mean litter size, fetal sex distribution and placental appearance were not affected by treatment with Isophorondiisocyanat an exposure level up to and including 4 mg/m3.

Reduction of fetal weight was evident in the 4 mg/m 3 group and treatment relationship could not be completely excluded for marginally impaired placental weight at the 4 mg/m3 exposure level.

Effect levels (maternal animals)

open allclose all
Key result
Dose descriptor:
NOAEC
Effect level:
1 mg/m³ air
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOAEC
Effect level:
0.929 mg/m³ air (analytical)
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
Mean fetal weights were statistically significantly reduced at the maternally toxic 4 mg/m3 exposure level and treatment relationship was evident for this finding.

Reduction in number of live offspring:
no effects observed
Description (incidence and severity):
Number of live fetuses were unaffected by treatment with Isophorondiisocyanat at an exposure level up to and including 4 mg/m3.
Changes in sex ratio:
no effects observed
Description (incidence and severity):
Effects of treatment with Isophorondiisocyanat on fetal sex distribution were not evident at an exposure level up to and including 4 mg/m 3 .
Changes in litter size and weights:
no effects observed
Description (incidence and severity):
Mean litter size were not affected by treatment with Isophorondiisocyanat an exposure level up to and including 4 mg/m3.
Changes in postnatal survival:
not specified
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
The total number of fetuses or litters with malformations revealed the highest value in the 1 mg/m3 exposure group (2.0 % of fetuses, 20.8 % of litters affected) and percentage of affected litters was nearly identical in the control (12.5%) and the 0.25 mg/m3 (13.0%) and 4 mg/m3 (11.5%) exposure groups so that dose relation was not evident. Futhermore, the total number of malformations was not statistically significantly different and lay well in the range of historical control data (in historical controls up to 6.9% of fetuses and up to 40.0% of litters revealed malformations; see Annex on page 650 to 654), so that treatment relation was not evident for the total number of malformed fetuses and litters.

Looking in detail for type of malformations and their incidence the following observations were made: The main number of malformations in dosed groups (domed head/ hydrocephalus internus, encephalomeningocele, shortened lower jaw, scapular cleft, missing lumbar vertebra and pelvic shift, dysplastic forelimb bones) was not dose related, these malformations were generally isolated findings and either seen as well in the current or in historical controls (see Annex on pages 655 to 667) at a comparable/ identical incidence. A fetus with a cleft in the sternum and additional osseous and cartilaginous findings was only seen in the 4 mg/m3 exposure group (fetus no. 429 of female no. 2103), but due to comparability with historical control data (see Annex on page 663), single appearance and severely retarded development of this fetus (fetal weight 2.88 g), a treatment related effect ofIPDI was not deduced from this observation.

With respect to malformations of the eyes seen in the actual study, one affected fetus was observed in the control group (eyehole reduced in size; most probably indicative of an eye malformation; since observation was made during skeletal evaluation, it is not to decide whether the observation is either indicative of microphthalmia or even anophthalmia), one fetus (with anophthalmia) in the 1 mg/m 3 exposure group and 3 fetuses in 2 litters of the 4 mg/m 3 exposure group (one fetus with microphthalmia, one fetus with microphthalmia left and anophthalmia right and one fetus with bilateral anophthalmia; the latter 2 fetuses originated from the same litter; altogether 1% of fetuses and 7.7% of litters affected at the 4 mg/m3 exposure level).

Treatment relationship for incidence of eye malformations was regarded unlikely for the following reasons: Malformations of the eyes belong to the most common spontaneous malformations of the rat strain used (up to 1.8% of fetuses and 20% of litters affected; data from gavage studies; see Annex on pages 889 to 896 for incidence in historical control and different dose groups) and include microphthalmia, anophthalmia and reduced size of eyehole. The incidence of eye malformations in the actual study lay well within the historical control data range and total incidence of malformations was neither affected. Even if - as a conservative approach -, a treatment related effect was considered, this effect would be regarded as being secondary to maternal toxicity (hypoxia). In the actual study females of the high 4 mg/m3 dose group showed bradypnea which most probably led to insufficient oxygen supply to their offspring. It is known from an earlier inhalational embryotoxicity study in this laboratory (performed under comparable exposure conditions; i.e. nose only exposure for 6 hours/day; cf. study no. T304 l 008 on page 890 of the Annex) that a high incidence of eye malformations in the highest dose group was reduced by oxygen supplementation of females during inhalation.

Thus, the incidence and type of fetal malformations were unaffected by treatment at an exposure level up to and including 4 mg/m3 . A marginal higher number of common eye malformations at the maternally toxic 4 mg/m 3 exposure level, which was well within the range of historical control data and had no effect on total number of malformations in this dose group, was regarded as incidental. Even, if treatment relationship was taken into consideration, this would be considered secondary to maternal toxicity (reduced oxygen supply to the offspring by maternal bradypnea).

Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
Fetal skeletal including cartilaginous tissue evaluation for degree of ossification and incidence of variations revealed no toxicologically relevant effects at an exposure level up to and including 1 mg/m3 .
Statistically significant observations regarding skeletal findings at the 0.25 mg/m3 exposure level comprised retarded ossification of distal phalanx of l st digit left and more progressed ossification of 2nd stemebrae. Fetal skeletal observations made with statistical significance at the 1 mg/m3 exposure level consisted of a reduced number of unossified distal phalanges of 1st digit right and retarded ossification of ih
cervical vertebral body. All these findings were regarded as incidental due to lack of dose relation, lack of statistical significance on a litter basis and comparability with the range of historical control data (see Annex on pages 675 to 715).

Furthermore, delayed ossification of 4th sacral vertebral arch (SVA), right was observed at the 1 mg/m3 exposure level on a litter basis only and without dose relation, so that toxicological relevance was not assumed.

Increased numbers of individual wavy ribs and sum of wavy ribs (exceeding the incidence in historical controls; see Annex on pages 675 to 715) were seen only in the 0.25 mg/m3 and l mg/m 3 exposure groups without dose relation. Wavy ribs are a common spontaneous skeletal variation in the rat strain used (cf. historical control


data in the Annex on pages 675 to 715) and were regarded as incidental in the actual study due to lack of dose relation and lack of statistical significance on a litter basis.

Statistically significant fetal skeletal findings at the 4 mg/m3 exposure level included retarded ossification of distal (Ist - 4th digit right, 1st and Yd digit left, 1st - 3rd toe right, I st - 5th toe left) and proximal phalanges (3rd and 4th digit bilateral) of digits
and toes, of metacarpal bones (5th bilateral), 6th sternal segment, ?1h cervical vertebral body (without dose relation), sacral (4th bilateral) and caudal vertebral arches (2nd bilateral) and caudal vertebral bodies (5th). Incidence of findings at the proximal phalanges of digits and distal phalanges of toes, of metacarpals, and sacral and
caudal vertebrae lay outside the range of recent historical control data on a fetal basis (see Annex on page 675 to 715) and although statistical significance on a litter basis was restricted to delayed ossification of proximal phalanges of digits (Yd bilateral,
4th right; incidence not covered by historical control data; see Annex on pages 675 to 715), treatment relationship was assumed for retarded ossification of these localizations in relation to as well impaired fetal weight.

Evaluation of cartilaginous tissues revealed slightly increased numbers of fetuses and litters with forked or unciform cartilaginous ends of 8th rib in the 4 mg/m 3 exposure group. Minor alterations of 8th rib are common spontaneous observations
in the rat strain used (cf. historical control data in the Annex on pages 881 to 888), statistical significance was not evident for these findings on a fetal and litter basis and incidence lay in/was comparable to the incidence in historical controls (see Annex on pages 881 to 888) so that toxicological relevance was not assumed.

Thus, summarizing evaluation of osseous and cartilaginous tissues, retarded
ossification of few localizations (phalangeal bones, single sternebrae and sacral vertebrae and few caudal vertebrae) was assumed at the maternally toxic 4 mg/m 3 exposure level in relation to impaired fetal weights.
Visceral malformations:
effects observed, non-treatment-related
Description (incidence and severity):
External deviations were not observed in this study.

Statistical significance was only evident for reduced number of tracheal findings (membraneous part of trachea slightly folded, lying in tracheal lumen; possibly of artefactual origin) in the 1 mg/m3 and 4 mg/m3 exposure groups and for reduced total number of fetuses with deviations in the 1 mg/kg exposure group. Based on lack of dose relationship, highest incidence of the tracheal finding in the actual control
group and lack of pathological significance per se for a reduced number, these findings were considered incidental.

Except of the finding of enlarged stomach and displaced kidneys in one fetus of the medium 1 mg/m3 exposure group, all deviations observed during visceral evaluation represented the normal range of scattering in the rat strain used and were of a common type i.e. comparable to spontaneous findings in historical control groups
(see Annex on pages 668 to 674 for historical control data). The unusual finding mentioned above as well as the more common findings revealed no dose relationship except for a marginally increased incidence of fetuses with slightly folded retinae
and of fetuses with testicular findings in the 4 mg/m3 exposure group.

Slightly folded retinae are a common finding in the rat strain used (incidence in the 4 mg/m3 exposure group 1.3% of fetuses and 11.5% of litters, incidence in historical controls up to 1.5% of fetuses and 17.4% of litters; up to 4.05% of fetuses and 30%
of litters as evaluated by a contract research laboratory; see Annex on page 673 and


674, respectively) and represents most probably an artefact. Thus toxicological relevance was not assumed for this observation in the 4 mg/m3 exposure group.

The number of slightly undescended or displaced testicles - regarded as a sign of retarded fetal development - was slightly increased in the 4 mg/m3 exposure group (4% of fetuses and 38.5% of litters) towards the actual control group (2.2% of fetuses and 25% of litters). Although incidence of the individual alterations lay well in the range of historical control data on a fetal and/or litter basis (see Annex on pages 668 to 674) and statistical significance was not evident, treatment relationship could not be completely excluded in relation to as well reduced fetal weights.

Thus, an effect on incidence and type of external and visceral deviations was not evident at an exposure level up to and including 1 mg/m3 while slightly retarded descensus testis could not be completely excluded at the maternally toxic 4 mg/m3 exposure level in relation to decreased fetal weights.
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
Reduction of fetal weight was evident in the 4 mg/m3 group and treatment relationship could not be completely excluded for marginally impaired placental weight at the 4 mg/m3 exposure level. A treatment related effect on the incidence and type of fetal malformations was not assumed at an exposure level up to and including 4 mg/m3. Slightly retarded ossification of few localizations (phalanges, sternebrae, sacral and caudal vertebrae) was assumed and slightly impaired descensus testi could not be completely excluded at the 4 mg/m3 exposure level in relation to decreased fetal weights and dose dependency. All signs of developmental toxicity observed at the 4 mg/m3 exposure level i.e. reduced fetal weight, delayed descensus testis and slightly retarded ossification were indicative of delayed fetal development and were only seen in the presence of maternal toxicity and thus considered a secondary effect.

Effect levels (fetuses)

open allclose all
Key result
Dose descriptor:
NOAEC
Effect level:
1 mg/m³ air (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: developmental toxicity
Dose descriptor:
NOAEC
Effect level:
0.929 mg/m³ air (analytical)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: developmental toxicity

Overall developmental toxicity

Key result
Developmental effects observed:
not specified

Any other information on results incl. tables

Result: not teratogenic

ACTUAL DOSE RECEIVED BY DOSE LEVEL BY SEX: Chemical analyses demonstrated  satisfactory stability and agreement 

between nominal and actual  concentrations of the test material.
MATERNAL TOXIC EFFECTS BY DOSE LEVEL: 
- Mortality and day of death: No mortalities were reported.
- Description, severity, time of onset and duration of clinical signs:  decreased respiratory rate (bradypnea), labored breathing,  breathing  sounds, reddish encrusted nostrils, serous nasal discharge, rough fur (4  mg/m3 group). Effects on breathing as well as  nasal discharge were not  observed in the other groups, while effects on nose and nostrils were  rare (maximum 2 females/group)  and likely related to restraint. Rough fur  occurred in some females of all study groups, including the control  group, but showed a  sharp increase in incidence with the 4 mg/m3 group. 
- Food/water consumption: Decreased feed intake throughout the exposure  period was observed in the 4 mg/m3 group  (14.7 % below control; p < 0.01)  and during the last interval (days 18-20) in the 0.25 mg/m3 group (p <  0.05, not dose related).  After start of inhalation, reduced feed intake  was observed in all study groups including control, most probably due to  the inhalation  procedure. Beyond this, feed intake was normal. No effects  on water intake and on excretion of urine and feces were observed in  any  group.
- Body weight: The body weight in the 4 mg/m3 group from day 0 to day 20  was lower by 7.9 %, the corrected body weight  (body weight minus unterine  weight) was lower by 9.2 %. The body weight gain in the 4 mg/m3 group  from day 0 to day 20 was  lower by 23.5 % (absolute; relative to initial  weight: -21.7 %; corrected: -91.3 %; compared to control; p < 0.01).   After start of inhalation, body weight loss was observed in all study  groups including control, most probably due to the inhalation  procedure.  Beyond this, body weight development was normal.
- Gross pathology incidence and severity: There were no treatment related  gross pathological findings in any group.
- Number pregnant per dose level: control: 24/27; 0.25 mg/m3: 23/27; 1  mg/m3: 24/27; 4 mg/m3: 26/27
- Number of implantations: control 11.9; 0.25 mg/m3: 11.9; 1 mg/m3: 13.0,  4 mg/m3: 12.0 (mean per female with implantation sites) 

= no significant  differences
- Pre and post implantation loss: control: 1.7 / 0.8; 0.25 mg/m3: 2.1 /  0.7; 1 mg/m3: 1.2 / 0.7; 4 mg/m3: 1.4 / 0.5 

(mean pre- / postimplantation  loss per female with implantation sites) = no significant differences
- Number of corpora lutea: control: 13.6; 0.25 mg/m3: 14.0; 1 mg/m3:  14.1, 4 mg/m3: 13.4 (mean per female with implantation sites)

 = no  significant differences
- Number aborting: No abortion in any group
- Number of resorptions: There were no females with total resorption in  any group.
- Duration of pregnancy: determined by cesarean section on day 20
- Other findings: Placental weights were marginally decreased at the 4  mg/m3 level (-6.6 %, not statistically significant but slightly 

below  historical control data range).
FETAL DATA: 
- Litter size and weights: mean fetal weight in control: 3.51 g; 0.25  mg/m3: 3.49 g; 1 mg/m3: 3.46 g; 4 mg/m3: 3.27 g, i.e. reduction of fetal  weight in 4 mg/m3 group (-6.8 %; p < 0.01)
- Number viable: control: 11.1; 0.25 mg/m3: 11.2; 1 mg/m3: 12.3; 4 mg/m3:  11.5, i.e. no treatment related findings
- Sex ratio: control: 49.3; 0.25 mg/m3: 48.3; 1 mg/m3: 50.0; 4 mg/m3:  52.0 % males, i.e. no treatment related findings
- Grossly visible abnormalities: There is no evidence for treatment  relation. A marginally higher number of common eye malformations in the 4  mg/m3 group (1 % of the fetuses and 7.7 % of litters affected vs. 0.4 %  of fetuses and 4.2 % of litters in control), which is well within the  range of historical control data (up to 1.8 % of fetuses and 20 % of  litters affected), is considered to be either incidental or secondary  (reduced oxygen supply to offspring by maternal bradypnea).
  control:    1.1 % of fetuses / 12.5 % of litters showed malformations
  0.25 mg/m3: 1.6 % of fetuses / 13.0 % of litters showed malformations
  1.0  mg/m3: 2.0 % of fetuses / 20.8 % of litters showed malformations
  4.0  mg/m3: 1.7 % of fetuses / 11.5 % of litters showed malformations
- External abnormalities: External deviations were not observed in this  study.
- Soft tissue abnormalities: Statistical significance was only evident  for reduced number of tracheal findings (membraneous part of trachea  slightly folded, lying in tracheal lumen; possibly of artefactual origin)  in the 1 mg/m3 and 4 mg/m3 groups and for reduced total number of fetuses  with deviations in the 1 mg/kg exposure group. Based on lack of dose  relationship (control: 23; 0.25 mg/m3: 11; 1 mg/m3: 6; 4 mg/m3: 10 %),  highest incidence of the tracheal finding in the actual control group and  lack of pathological significance per se for a reduced number, these  findings were considered incidental. Other deviations observed during  visceral evalution were either common or without dose relationship. In  conclusion, an effect on incidence and type of external and visceral  deviations was not evident at an exposure level up to and including 1  mg/m3, while slightly retarded descensus testis (4 % of fetuses and 38.5  % of litters vs. 2.2 % of fetuses and 25 % of litters in the control  group) was observed at the maternally toxic 4 mg/m3 exposure level. In  relation to decreased fetal weights treatment relationships could not be  totally excluded, although the individual alterations lay well in the  range of historical data and statistical significance was not evident.
  control:    27.0 % of fetuses / 95.8 % of litters showed deviations
  0.25 mg/m3: 24.4 % of fetuses / 87.0 % of litters showed deviations
  1.0  mg/m3: 17.0 % of fetuses / 87.5 % of litters showed deviations
  4.0  mg/m3: 23.0 % of fetuses / 96.2 % of litters showed deviations
- Skeletal abnormalities: Fetal skeletal including cartilaginous tissue  evaluation for degree of ossification and 

incidence of variations  relealed no toxicologically relevant effects at an exposure level up to  and including 1 mg/m3. Dose relation 

was missing for all findings at 0.25  and 1 mg/m3, and statistical significance was absent either on a fetus  base, or on a litter base, 

or for both. Statistically significant fetal  skeletal findings at the 4 mg/m3 exposure level included retarded  ossification of distal and 

proximal phalanges of digits and toes, of  metacarpal bones, 6th sternal segment, 7th cervical vertebral body,  sacral and caudal 

vertebral arches and caudal vertebral bodies. Incidence  of findings at the proximal phalanges of digits and distal phalanges of  toes, 

of metacarpals, and sacral and caudal vertebrae lay outside the  range of recent historical control data on a fetal basis, and although  

statistical significance on a litter basis was restricted to delayed  ossification of proximal phalanges of digits, treatment relationship 

was  assumed for retarded ossification of these localizations in relation to  as well impaired fetal weight. Other findings in the 

4 mg/m3 group were  considered to be of no toxicological relevance.

Applicant's summary and conclusion

Conclusions:
Animals treated with the test substance Isophorone diisocyanate (IPDI) at the 4 mg/m3 exposure level showed signs of maternal toxicity (respiratory tract affected, decrased respiratory rate (bradypnea), laboured breathing, breathing sounds, reddish encrusted nostrils, serous nasal discharge, rough fur, decreased feed intake, body weight loss). The incidence and type of fetal malformations were unaffected by treatment at an exposure level up to and including 4 mg/m3. Even if a treatment related effect was taken into consideration, it would be considered secondary to maternal toxicity. Thus under the conditions of this study the test substance Isophorone diisocanate is considered to be not teratogenic. All signs of developmental toxicity observed at the 4 mg/m3 exposure level (i.e. reduced fetal weights, delayed descensus testis and slightly retarded ossification) were indicative of delayed fetal development and were only seen in the presence of maternal toxicity and thus considered a secondary effect. Animals treated with the test substance at the 4 mg/m3 exposure level showed signs of maternal toxicity (respiratory tract affected, decrased respiratory rate (bradypnea), laboured breathing, breathing sounds, reddish encrusted nostrils, serous nasal discharge, rough fur, decreased feed intake, body weight loss). Summarizing and evaluating all data investigated the following no-observed-adverse-effect concentrations (NOAECs) were determined: Maternal toxicity: 1 mg/m3
Developmental toxicity: 1 mg/m3
Executive summary:

Female inseminated Wistar rats were treated daily for 6 hours/day by inhalation (nose-only) with Isophorone diisocyanate (IPDI) from day 6 to day 19 post coitum to examine potential developmental toxicity effects of the test substance. Dosages used were 0 (air control); 0.25; 1 and 4 mg/m3, respectively.

Animals treated with the test substance Isophorone diisocyanate (IPDI) at the 4 mg/m3 exposure level showed signs of maternal toxicity (respiratory tract affected, decrased respiratory rate (bradypnea), laboured breathing, breathing sounds, reddish encrusted nostrils, serous nasal discharge, rough fur, decreased feed intake, body weight loss). No mortalities were reported. Necropsy revealed no treatment releated gross pathological findings at an exposure level up to and including 4 mg/m3. With respect to the parameters of intrauterine development, gestation rate, postimplantation loss, mean litter size, fetal sex distribution and placental appearance were not affected by treatment with the test substance at an exposure level up to and including 4 mg/m3. Reduction of fetal weight was evident in the 4 mg/m3 group and treatment relationship could not be completely excluded for marginally impaired placental weight at the 4 mg/m3 exposure level.

The incidence and type of fetal malformations were unaffected by treatment at an exposure level up to and including 4 mg/m3. Slightly retarded ossification of few localizations (phalanges, sternebrae, sacral and caudal vertebrae) was assumed and slightly impaired descensus testis could not be completely excluded at the 4 mg/m3 exposure level in relation to decreased fetal weights and dose dependency. All signs of developmental toxicity observed at the 4 mg/m3 exposure level (i.e. reduced fetal weights, delayed descensus testis and slightly retarded ossification) were indicative of delayed fetal development and were only seen in the presence of maternal toxicity and thus considered a secondary effect. Summarizing and evaluating all data investigated the following no-observed-adverse-effect concentrations (NOAECs) were determined: Maternal toxicity: 1 mg/m3

Developmental toxicity: 1 mg/m3