Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information

No reliable multi-generation study is available for triethyl phosphate. In an early investigation (Gumbmann, 1968) not following GLP or Guideline with only 5 rats/sex and dose the effects of triethyl phosphate in food were investigated. The animals were treated for 92 days prior to mating and during mating and weaning. This study is of low significance due to the low number of animals per dose group, the absence of analytics and definition of doses, insufficient parameters investigated and inadequate description of results.

However, taking into account Guideline-compliant subacute and subchronic repeated dose toxicity studies in rats and Guideline-compliant developmental toxicity studies in rats and rabbits with triethyl phosphate there is no indication of a potential to interfere with reproduction.

Link to relevant study records
Reference
Endpoint:
fertility, other
Remarks:
other: repeated dose toxicity studies
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
1 (reliable without restriction)
Reason / purpose:
reference to same study
Reason / purpose:
reference to same study
Principles of method if other than guideline:
OECD Guideline 407 and 408 Study
GLP compliance:
yes
Limit test:
no
Justification for study design:
repeated dose toxicity studies including reproductive parameters can be used in a weight of evidence approach for the assessment of reproductive toxicity
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: CH1/3003
- Lab specific test material number: 207699/A
- Expiration date of the lot/batch: 2018-03-09
- Purity: 99.6%

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: stability was analytically confirmed for at least 5 hours over the concentration range of 1 to 200 mg/mL and in a refrigerator for at least 10 days. Test facility No. 514832
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: none
Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
see endpoint study records listed under 'cross-reference'
Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
see endpoint study records listed under 'cross-reference'
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
see endpoint study records listed under 'cross-reference'
Duration of treatment / exposure:
28 day and 90 day study
Frequency of treatment:
once daily
Details on study schedule:
see endpoint study records listed under 'cross-reference'
Dose / conc.:
1 000 mg/kg bw/day
Remarks:
doses of 10, 100, and 1000 mg/kg bw/day were tested in the 28d oral toxicity study
Dose / conc.:
700 mg/kg bw/day
Remarks:
doses of 60, 200, and 700 mg/kg bw/day were tested in the 90d oral toxicity study
No. of animals per sex per dose:
5 per sex/dose in the 28 day study and 10 per sex/dose in the 90 day study
Control animals:
yes, concurrent vehicle
Details on study design:
see endpoint study records listed under 'cross-reference'
Parental animals: Observations and examinations:
Weight determinations in the 90d oral toxicity study: ovaries, testes, uterus (including cervix), prostate, seminal vesicles including coagulating glands
Macroscopic and microscopic in the 90d oral toxicity study: cervix, epididymides, female mammary gland area, ovaries, pituitary gland prostate gland, seminal vesicles incuding coagulation gland, testes, uterus vagina
Oestrous cyclicity (parental animals):
All females in the 90d oral toxicity study had a daily lavage from Day 72 up to and including Day 92 to determine the stage of estrous.
Sperm parameters (parental animals):
From all control and high dosed males of the 90d oral toxicity study additional slides of the testes were prepared to examine staging of spermatogenesis. The testes were processed, sectioned at 3-4 micrometers, and stained with PAS/haematoxylin.
Reproductive function: oestrous cycle:
no effects observed
Description (incidence and severity):
No test item related changes were noted in estrous cycle determination in the 90d oral toxicity study. One control female (no. 47) showed an irregular estrous cycle length and one 200 mg/kg female (no. 65) showed extended estrus. All other females showed a normal (regular) estrous cycle of 4/5 days. The incidence of irregular estrous cycle length showed no relationship to the dose, and was therefore considered unrelated to treatment.
Reproductive function: sperm measures:
no effects observed
Description (incidence and severity):
Spermatogenic staging profiles were normal for all males examined in the control and high dose group in the 90d oral toxicity study.
Weight determinations in the 90d oral toxicity study showed no treatment-related effects on the reproductive organs of male and female rats (ovaries, testes, uterus (including cervix), prostate, seminal vesicles including coagulating glands)
Macroscopic and microscopic investigtions in the 90d oral toxicity study showed no treatment related alterations that differ in prevalence, severity, or histologic character to incidental tissue alterations (cervix, epididymides, female mammary gland area, ovaries, pituitary gland prostate gland, seminal vesicles incuding coagulation gland, testes, uterus vagina)
Dose descriptor:
NOAEL
Remarks:
systemic toxicity
Effect level:
200 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: 90 day repeated dose toxicity study
Dose descriptor:
NOAEL
Remarks:
reproductive organ toxicity
Effect level:
>= 700 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: 90 day repeated dose toxicity study
Reproductive effects observed:
no

Repeated dose toxicity of triethyl phosphate was investigated in two comprehensive guideline studies performed according to OECD TG 407 and 408 and conducted in compliance with GLP. In the 28 day study (performed 1992) the test item was given via oral gavage in doses of 0, 10, 100, and 1000 mg/kg bw/day to 5 male and 5 female Wistar rats per dose group. No treatment-related effects on reproductive organs were noted.

In the 90 day study (performed 2017) the test item was given via oral gavage in doses of 0, 60, 200 or 700 mg/kg bw/day to 10 male and 10 female Wistar rats per dose group.

The overall NOAEL for repeated dose toxicity is established at 200 mg/kg bw/day based on effects on liver weight in the 90 day study. The NOAEL for effects to reproductive organs is established with >= 700 mg/kg bw/day, the highest dose in 90 day study. Reproductive parameters assessed in this study (estrous cycle regularity, spermatogenesis staging) and morphology of gonads and accessory reproductive organs revealed no treatment-related changes.There were no effects on the weight of the gonads (males: testes and epididymes, seminal vesicles including coagulating glands; females ovaries, uterus including cervix) or the microscopic examined integrity of the gonads (males: epididymides, prostate, seminal vesicles and testes; females: uterus and ovaries, vagina) at any dose tested.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Additional information

No reliable generation study is available for triethyl phosphate. In an early investigation (Gumbmann, 1968) not following GLP or Guideline with only 5 rats/sex and dose the effects of triethyl phosphate in food were investigated. The animals were treated for 92 days prior to mating and during mating and weaning. This study is of low significance due to the low number of animals per dose group, the absence of analytics and definition of doses, insufficient parameters investigated and inadequate description of results.

Repeated dose toxicity of triethyl phosphate was investigated in two comprehensive guideline studies performed according to OECD TG 407 and 408 and conducted in compliance with GLP. In the 28 day study (performed 1992) the test item was given via oral gavage in doses of 0, 10, 100, and 1000 mg/kg bw/day to 5 male and 5 female Wistar rats per dose group. No treatment-related effects on reproductive organs were noted.

In the 90 day study (performed 2017) the test item was given via oral gavage in doses of 0, 60, 200 or 700 mg/kg bw/day to 10 male and 10 female Wistar rats per dose group.

The overall NOAEL for repeated dose toxicity is established at 200 mg/kg bw/day based on effects on liver weight in the 90 day study. The NOAEL for effects to reproductive organs is established with >= 700 mg/kg bw/day, the highest dose in 90 day study. Reproductive parameters assessed in this study (estrous cycle regularity, spermatogenesis staging) and morphology of gonads and accessory reproductive organs revealed no treatment-related changes.There were no effects on the weight of the gonads (males: testes and epididymes, seminal vesicles including coagulating glands; females ovaries, uterus including cervix) or the microscopic examined integrity of the gonads (males: epididymides, prostate, seminal vesicles and testes; females: uterus and ovaries, vagina) at any dose tested.

Guideline- and GLP compliant developmental toxicity studies on rats and rabbits do also not point to reproductive toxicity. In rats, gestation rate, intrauterine development, resorption rate and accordingly the number of fetuses, fetal sex and weight and appearance of placentas were unaffected by treatment up to and including the highest dose. The NOAEL for developmental/reproductive toxicity was 625 mg/kg bw/day, the highest dose tested in this study. Also in rabbits no treatment related adverse effects became obvious, with a NOAEL of 250 mg/kg bw/day, representing the highest dose tested.  

In summary, based on the available repeated dose and developmental toxicity studies there is no indication of potential interferene of the substance with reproduction.

Effects on developmental toxicity

Description of key information

A developmental toxicity study performed according to OECD 414 study in rats showed no evidence of a teratogenic potential up to the highest dose of 625 mg/kg bw/day (NOAEL developmental toxicity). In the highest dose there was reduction of body weight gain, food intake and feces excretion and signs of narcotic effects as indicator of maternal toxicity (NOAEL 125 mg/kg bw/day).

Based on a developmental toxicity study in rabbits (OECD 414) the maternal No Observed Adverse Effect Level (NOAEL) for Triethyl phosphate was established as being 80 mg/kg bw/day based on calm behavior, reduced food consumption and transient body weight effects at 250 mg/kg bw/day. The developmental NOAEL was determined to be at least 250 mg/kg bw/day.

Link to relevant study records

Referenceopen allclose all

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study.
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Qualifier:
according to
Guideline:
other: EPA TSCA Test Guidelines (401 CFR Parts 796, 797, 798: 798.4900 Developmental Toxicity Study, September 27, 1985, and Revised Edition May 20, 1987)
Qualifier:
according to
Guideline:
other: EC guidelines (Commision Directive 88/302/EEC, Official Journal of the European Communities L 133, May 30, 1988).
GLP compliance:
yes
Limit test:
no
Species:
rat
Strain:
Wistar
Route of administration:
oral: gavage
Vehicle:
water
Analytical verification of doses or concentrations:
yes
Details on mating procedure:
The animals were mated by placing two females in a Type III cage with one male rat overnight. If sperm was found in a vaginal smear taken on the morning following mating, this day was regarded as day 0 of gestation.
Duration of treatment / exposure:
from day 6 to day 15 p.c.
Frequency of treatment:
daily
Duration of test:
The fetuses were delivered by cesarian section on the 20th day of gestation.
Dose / conc.:
25 mg/kg bw/day (actual dose received)
Dose / conc.:
125 mg/kg bw/day (actual dose received)
Dose / conc.:
625 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
25/dose
Control animals:
yes, concurrent vehicle
Details on study design:
The dose levels were selected according to a preceding rang-finding study in 4-5 rats with doses of 300, 500, and 625 mg/kg bw/d.
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes, twice daily

DETAILED CLINICAL OBSERVATIONS: Yes, twice daily

BODY WEIGHT: Yes, on days 0, 6-15, and 20 pc

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
Ovaries and uterine content:
according to Guideline
Fetal examinations:
External, visceral and skeletal examination of the fetuses
Statistics:
Fisher's exact significance test for fertility rate and gestation rate
F-test and t-test or Welch t-test for feed intakes, body weight gains, number of corpora lutea per dam, implantations per dam, live fetuses per dam etc.
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
The appearance and behavior of the dams was unaffected up to and including the dosage of 125 mg/kg.The dams of the 625 mg/kg group revealed clinical signs like bloddy mouth, staggering gait and ventral posture. The staggering gait and the ventral posture are considered to be a sign of the narcotic efficacy of TEP.
Mortality:
no mortality observed
Description (incidence):
one dam of the control group died on day 18 pc
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
body weight gains of the dams in the 625 mg/kg bw group statistically significant reduced between day 6-15 pc (15.1 versus 23.9 g in control) and day 0-20 corrected (24.5 versus 31.8 g); food consumption was lower in this dose group on day 6-11 pc.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No treatment related findings were evident at necropsy up to and including the dose of 625 mg/kg bw.
Description (incidence and severity):
The number of corpora lutea, preimplantation losses and implantations were comparable in all experimental groups, with exception of the significantly lower preimplantation losses in the 25 mg/kg bw group.
Description (incidence and severity):
none
Description (incidence and severity):
the number of resorptions
Description (incidence and severity):
no changes
Description (incidence and severity):
No. of pregnants: 22, 20, 22, 20
Dose descriptor:
NOAEL
Effect level:
125 mg/kg bw/day
Based on:
test mat.
Basis for effect level:
clinical signs
body weight and weight gain
Abnormalities:
no effects observed
Fetal body weight changes:
no effects observed
Description (incidence and severity):
none: fetal body weight. 3.48, 3.55, 3.59, 3.44 g in control, low, mid, high dose group
Reduction in number of live offspring:
no effects observed
Description (incidence and severity):
none: No. of fetuses per dam: 10.5, 11.6, 11.6, 10.6 in control, low, mid, high dose group
Changes in sex ratio:
no effects observed
External malformations:
no effects observed
Description (incidence and severity):
see Table
Skeletal malformations:
no effects observed
Description (incidence and severity):
see Table
Visceral malformations:
no effects observed
Description (incidence and severity):
see Table
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects
External, visceral and skeletal examination of the fetuses revealed no effects on intrauterine development
Dose descriptor:
NOAEL
Effect level:
625 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no treatment related effects on development at any dose
Abnormalities:
no effects observed
Developmental effects observed:
no

External, skeletal and visceral malformations in viable fetuses:

 Malformation  Dose (mg/kg b.w./day)         
   0  25  125  625
 fetuses/ (Litters Affected) (n)  -  -  -  -
 Microphtalmia  1  1  1  2 (2)
 Hydrocephalus internus  -  -  -  1
 Pelvis dislocated  1  -  -  -
 Malformation of vertebra  4 (3)  -  1  1
 Fusion of ribs  1  -  -  -
 Thickened cervical rib  1  -  -  -
 Malformation of forelimb bones  1  -  -  -
 Exoccipitale dysplastic  1  -  -  -
 Dislocation of atlanto-occipital joint (probably artifact +)  -  1  -  1
  Fetuses per group (n)  231  232  242  213
malformed fetuses (n)  7  2  2  5
  (%)  3,0  0,9  0,8  2,4
 Litters per Group (n)  22  20  22  20
 Litters with malformations (n)  5  2  1  3
  (%)  22,7  10,0  5,0  15,0

+ = nevertheless included in the calculation

some fetuses revealed more than one malformation, therefore the number of malformations does not necessarily reflect the number of fetuses affected.

Executive summary:

In a developmental toxicity study following OECD 414 groups of 25 inseminated female Wistar rats per dose group were treated daily by gavage with TEP formulated in demineralised water from days 6 to day 15 p.c. in doses of 0, 25, 125 or 625 mg/kg body weight, respectively. The fetuses were delivered by cesarian section on day 20 of gestation.

The dams of the 625 mg/kg group revealed clinical signs like bloddy mouth, staggering gait and ventral posture. The staggering gait and the ventral posture are considered to be a sign of the narcotic efficacy of TEP.

Body weight gain (day 6 -15 p.c.), feed intake (day 6 -11p.c.) and accordingly the feces excretion were reduced in the 625 mg/kg group.

The intrauterine development was not affected by the treatment including external, visceral and skeletal examination of the fetuses. A teratogenic potential was not evident.

The NOAEL were:

Maternal toxicity: 125 mg/kg bw./day

Developmental toxicity: 625 mg/kg bw./day.

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2016/2017
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Qualifier:
according to
Guideline:
EU Method B.31 (Prenatal Developmental Toxicity Study)
Qualifier:
according to
Guideline:
EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)
GLP compliance:
yes (incl. certificate)
Limit test:
no
Specific details on test material used for the study:
STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: room temperature
- Stability under test conditions: stable
- Solubility and stability of the test substance in the solvent/vehicle: stability was analytically confirmed for at least 5 hours over the concentration range of 1 to 200 mg/mL and in a refrigerator for at least 10 days, Test Facility Study No. 514832
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: none
Species:
rabbit
Strain:
New Zealand White
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River, Chatillon sur Chalaronne, France
- Untreated females from a non-inbred laboratory colony were mated at the suppoier and were at day 0 or 1 post-coitum on arrival at the Test Facility (day 0 post-coitum is the day of successful mating)
- Age at delivery: 17-19 weeks;
- Fasting period before study: none
- Housing: individually
- Diet: ad libitum
- Water: ad libitum
Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
Formulations (w/w) were prepared daily within 5 hours prior to dosing and were homogenized to a visually acceptable level. Adjustment was made for specific gravity of the test item. No correction was made for the purity/composition of the test item.

VEHICLE
- Justification for use and choice of vehicle (if other than water): water was chosen based on trial formulations performed at Charles River and information provided by the Sponsor.
- Amount of vehicle (if gavage): 5 ml/kg bw
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples of dose preparations were taken on a single occasion during the treatment phase (20 February 2017), and were stored and dispatched on dry ice to the test site for formulation analysis. Samples of formulations were analyzed for homogeneity (highest and lowest concentration) and accuracy of preparation (all concentrations).
The accuracy of preparation was considered acceptable if the mean measured concentrations were 90-110% of the target concentration. Homogeneity was demonstrated if the coefficient of variation was ≤ 10%.
Stability in the vehicle was confirmed in a separate study (Test Facility Study No. 514832).
Details on mating procedure:
Untreated females were mated at the Supplier and were at Day 0 or 1 post-coitum on arrival at the Test Facility (Day 0 post-coitum is the day of successful mating).
Duration of treatment / exposure:
Day 6 - 28 post coitum inclusive
Frequency of treatment:
once daily
Duration of test:
All animals surviving to the end of the observation period (Day 29 post-coitum) were euthanised by intravenous injection of pentobarbital (approx. 1 mL/kg Euthasol®20%) and subjected to an external, thoracic and abdominal examination, with special attention being paid to the reproductive organs and the fetuses.
Dose / conc.:
30 mg/kg bw/day (actual dose received)
Dose / conc.:
80 mg/kg bw/day (actual dose received)
Dose / conc.:
250 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
Each group consisted of 22 mated female rabbits.
Control animals:
yes, concurrent vehicle
Details on study design:
Rationale for dose levels
Dose levels were selected based on the results of a dose range finding study (Project 514830). In this latter study dose levels of 75, 150 and 300 mg/kg bw/day were tested in 6 pregnant rabbits per dose and control from gestational day 6 to 29 by oral gavage. One female in the mid and high dose each was euthanized in extremis on day 18 pc. Both females had shown body weight loss and (severely) reduced food consumption. Calm and/or lethargic behavior was noted in all females of the treatment groups after dosing, showing a dose related incidence and severity relationship. In all females treated at 300 mg/kg, except one, additional flat posture, ventro-lateral and/or lateral recumbency was observed on many days during treatment. Reduced food consumption between Days 6-16 post-coitum with concurrent body weight loss in this period was observed in females treated at 300 mg/kg. Both subsequently recovered. In the 150 mg/kg bw group transient periods of lower food consumption and body weight gain was observed. No effects were seen at 75 mg/kg bw. A slight, not statistically significant increase in liver weight was recorded for the high dose group. No effects on pregnancy or fetuses was seen.
Based on the results of this dose range finding study, selected dose levels for the main study were 30, 80 and 250 mg/kg bw/day.
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once daily

BODY WEIGHT: Yes
- Time schedule for examinations: Days 2, 6, 9, 13, 16, 20, 23, 26, 29 post-coitum

FOOD CONSUMPTION: Yes
- Days 2-6, 6-9, 9-13, 13-16, 16-20, 20-23, 23-26 and 26-29 post-coitum

WATER CONSUMPTION: Yes
- Subjective appraisal was maintained during the study, but no quantitative investigation was introduced as no treatment related effect was suspected.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
- Organs examined: external, thoracic and abdominal examination, with special attention being paid to the reproductive organs;
- Terminal body weight, liver weight and gravid uterus weight were recorded
Ovaries and uterine content:
The uteri, placentae and ovaries were examined, and the numbers of fetuses, early and late resorptions, total implantations and corpora lutea were recorded. Gravid uterine weights were recorded, and net body weights and net body weight changes were calculated.
Fetal examinations:
External, visceral, and skeletal findings were recorded as developmental variations (alterations in anatomic structure that are considered to have no significant biological effect on animal health or body conformity and/or represent slight deviations from normal) or malformations (those structural anomalies that alter general body conformity, disrupt or interfere with normal body function, or may be incompatible with life).

External:
Each viable fetus was examined in detail and weighed. All live fetuses were euthanized by administration of approximately 0.3 mL (= 60 mg) of sodium pentobarbital into the oral cavity using a small flexible plastic or metal feeding tube. Recognizable fetuses of females that were killed in extremis were examined externally. Nonviable fetuses (the degree of autolysis was minimal or absent) were examined and weighed. For late resorptions a gross external examination was performed (if possible). Late resorptions with malformations were fixed in 10% buffered formalin.

Visceral (Internal):
All fetuses were examined for visceral anomalies by dissection in the fresh (non-fixed) state. The thoracic and abdominal cavities were opened and dissected using a technique described by Stuckhardt and Poppe. This examination included the heart and major vessels. Fetal kidneys were examined and graded for renal papillae development as described by Woo and Hoar. The sex of all fetuses was determined by internal examination.

The heads were removed from approximately one-half of the fetuses in each litter and placed in Bouin's solution. Tissues were then transferred to a 70% aqueous ethanol (Klinipath, Duiven, The Netherlands) for subsequent processing and soft-tissue examination of all groups using the Wilson sectioning technique. After examination, the tissues were stored in 10% formalin. The heads from the remaining one-half of the fetuses in each litter of all groups were examined by a mid-coronal slice.

All carcasses, including the carcasses without heads, were eviscerated, skinned and fixed in identified containers containing 96% aqueous ethanol for subsequent examination of skeletons.

Skeletal:
The eviscerated fetuses from all groups, following fixation in 96% aqueous ethanol, were macerated in potassium hydroxide and stained with Alizarin Red S by a method similar to that described by Dawson. Subsequently, the skeletal examination was done on all fetuses from Groups 1 and 4. Based on a possible treatment related effect in the high dose group, skeletal examination was extended to all fetuses from the low and mid dose group.

The specimens of all groups were archived in glycerin with bronopol as preservative.

A few bones were not available for skeletal examination because they were accidentally damaged or lost during processing. The missing bones were listed in the raw data; evaluation by the fetal pathologist and study director determined there was no influence on the outcome of the individual or overall skeletal examinations, or on the integrity of the study as a whole.
Statistics:
The following statistical methods were used to analyze the data:
- If the variables could be assumed to follow a normal distribution, the Dunnett-test (many-to-one t-test) based on a pooled variance estimate was applied for the comparison of the treated groups and the control group.
- The Steel-test (many-to-one rank test) was applied if the data could not be assumed to follow a normal distribution.
- The Fisher Exact-test was applied to frequency data.
- The Mann Whitney test was used to compare mean litter proportions (percent of litter) of the number of viable and dead fetuses, early and late resorptions, total resorptions, pre- and post-implantation loss, and sex distribution.
- Mean litter proportions (percent per litter) of total fetal malformations and developmental variations (external, visceral and skeletal), and each particular external, visceral and skeletal malformation or variation were subjected to the Kruskal-Wallis nonparametric ANOVA test to determine intergroup differences. If the ANOVA revealed statistically significant (p<0.05) intergroup variance, Dunn’s test was used to compare the compound-treated groups to the control group.

All tests were two-sided and in all cases p < 0.05 was accepted as the lowest level of significance. Group means were calculated for continuous data and medians were calculated for discrete data (scores) in the summary tables. Test statistics were calculated on the basis of exact values for means and pooled variances. Individual values, means and standard deviations might be rounded off before printing. Therefore, two groups might display the same printed means for a given parameter, yet display different test statistics values.

No statistics were applied for data on maternal survival, pregnancy status, group mean numbers of dead fetuses, early and late resorptions, and pre- and post-implantation loss.
Indices:
For each litter the following calculations were performed:

Pre-implantation loss (%) = (number of corpora lutea - number of implantation sites) divided by the number of corpora lutea x 100
Post-implantation loss (%) = (number of implantation sites - number of live fetuses) divided by the number of implantation sites x 100
The fetal developmental findings were summarized by: 1) presenting the incidence of a given finding both as the number of fetuses and the number of litters available for examination in the group; and 2) considering the litter as the basic unit for comparison, calculating the number of affected fetuses as a mean litter proportion on a total group basis, where:

Viable fetuses affected/litter (%) = number of viable fetuses affected/litter divided by the number of viable fetuses/litter x 100
Historical control data:
available
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
No maternal toxicity was observed up to and including 80 mg/kg.
The majority of the high dose females treated at 250 mg/kg bw/day showed treatment related calm behavior during several days up to the entire treatment period, ranging from slight to moderate severity. Moderate effects were seen on 1-2 days only in 3 animals.
Reduced faeces production, varying in duration and severity, was noted in all groups, including the vehicle control group. The incidence was increased in the 250 mg/kg bw/day treated females compared to the concurrent controls (i.e. 13 out of 22 control females compared with 19 out of 22 high dose females).
Female no. 21 (control group) showed moderately labored respiration directly after dosing on Day 7 post-coitum. Based on the slightly labored respiration observed on Day 8 post-coitum, dosing was omitted for this female on this day and continued from Day 9 post-coitum onwards.
For female nos. 05 (control), 29 (30 mg/kg bw/day), 65, 661 (80 mg/kg bw/day) and 70 (250 mg/kg bw/day) incidental red fluid was observed on the manure tray during the treatment period. All these females were pregnant with viable fetuses. Red fluid on the manure tray was also noted for female no. 87 between Days 13-25 post-coitum. This female had resorptions only. At the incidence observed and without a dose related incidence trend, this was considered not treatment related.
The incidence of alopecia, wounds, scabs, scars, slight swelling, piloerection, dark eyes, broken teeth, lean appearance, diarrhea remained within the range of background findings to be expected for rabbits this strain and age.
Mortality:
no mortality observed
Description (incidence):
No treatment related mortality occurred up to 250 mg/kg bw/day.
Female no. 38 (30 mg/kg bw/day) and no. 69 (250 mg/kg bw/day) were euthanized in extremis on Day 16 and 18 post-coitum, respectively. Both females had limited to no food consumption for a prolonged period (up to 16 days) and showed a body weight loss ranging between 4 to 11%. For female no. 69 piloerection and pale and lean appearance were noted up to 4 days prior to euthanasia. These effects are not uncommon for rabbits of this strain and age. At the incidence observed and without a dose relationship, this was considered not treatment-related.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Body weights and body weight gain were unaffected by treatment up to and including 80 mg/kg bw/day.
At 250 mg/kg bw/day, absolute and relative food consumption was reduced from start treatment onwards up to Day 23 post-coitum. Concurrent body weight loss on Day 9 post-coitum (3 days after start treatment) was observed in the majority of the 250 mg/kg bw/day treated females, with continued body weight loss in individual animals throughout the treatment period. Between Days 13 and 23 post-coitum, mean body weight gain was reduced in these high dose females compared with the concurrent controls; not reaching statistical significance. From Day 26 post-coitum onwards, body weight gain was within the range of the control group. The absolute mean body weight was in the range of the control group from day 23 post-coitum onwards.
Body weight gain corrected for weight of the gravid uterus was unaffected by treatment up to 250 mg/kg bw/day at sacrifice.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Food consumption:
No treatment-related effects were observed up to 80 mg/kg bw/day.
In the first 3 days of treatment absolute and relative food consumption was strongly and significantly reduced in 250 mg/kg bw/day treated females compared with the vehicle control group. Up to Day 23 post-coitum, absolute and relative food consumption were still reduced in the 250 mg/kg bw dose group (only reaching statistical significance at Days 16-20 postcoitum). From Day 23 post-coitum onwards, food consumption was within the range of the control group again.
Reduced faeces production, varying in duration and severity, was noted in all groups, including the vehicle control group. However, as the incidence was increased in females treated at 250 mg/kg compared with the vehicle controls, low and mid dose groups, which could be correlated with the reduced food consumption in this group, it was therefore considered treatment related.
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
Absolute and relative liver weights and (gravid) uterus weight remained within the same range as the vehicle control group up to 250 mg/kg.
Gross pathological findings:
no effects observed
Description (incidence and severity):
No treatment-related macroscopic findings were noted up to 250 mg/kg bw/day.
A reduced size of the gallbladder was observed for one female of the 30 mg/kg bw/day group (no. 38) which was euthanized in extremis on Day 16 post-coitum; no macroscopic findings were noted for female no. 69 (250 mg/kg bw/day), which was also euthanized in extremis.
Incidental findings at macroscopic examination were within the normal range for rabbits of this strain and age.
Number of abortions:
no effects observed
Description (incidence and severity):
see Table 1
Pre- and post-implantation loss:
no effects observed
Description (incidence and severity):
see Table 2: The number of corpora lutea, implantation sites and pre-implantation loss in the control and treatment groups were similar and within the range of normal biological variation.
Total litter losses by resorption:
no effects observed
Description (incidence and severity):
see Table 1: Two individual females with resorptions only i.e. female nos. 55 (80 mg/kg) and 87 (250 mg/kg) were observed as incidental finding.
Early or late resorptions:
effects observed, non-treatment-related
Description (incidence and severity):
see Tables 2 and 3: The number of early resorptions and consequently the post-implantation loss were increased in the 80 and 250 mg/kg groups compared with the concurrent controls (not statistically significant). The percentage of early resorptions per litter was 7.4 and 8.1 in the mid and high dose groups, respectively, compared with 4.0 in the concurrent control group. It should be noted that individual females with resorptions only contributed to the increased percentages of early resorptions in these groups; i.e. female nos. 55 (80 mg/kg bw/day) and 87 (250 mg/kg bw/day). When excluding these females, the total number of early resorptions was 7, 5, 4 and 6 for the control, 30, 80 and 250 mg/kg bw/day groups, respectively.

This increase was contributed to two individual females in each of these dose groups with resorptions only, which were considered incidental findings. In the remaining females the number of early resorptions and post implantation loss remained within the same range compared with the concurrent controls. Taken together, the observed effects were considered not to be treatment related.
Dead fetuses:
no effects observed
Changes in pregnancy duration:
no effects observed
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): no effects observed
Changes in number of pregnant:
no effects observed
Description (incidence and severity):
see Table 1: A total of eight females were found not pregnant at necropsy; four, zero, three and one in the respective control, 30 mg/kg bw, 80 mg/kg and 250 mg/kg groups. As this occurred mainly in the control group and treatment started on Day 6 post-coitum after implantation, this was incidental and not related to treatment.
Details on maternal toxic effects:
The combination of calm behavior (slight severity), reduced food consumption and concurrent body weight effects at 250 mg/kg was considered treatment related and adverse.
Dose descriptor:
NOAEL
Effect level:
80 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: combination of calm behavior (slight severity), reduced food consumption and concurrent body weight effects at 250 mg/kg bw
Abnormalities:
no effects observed
Fetal body weight changes:
no effects observed
Description (incidence and severity):
see Table 2: No treatment related effect on fetal body weight was observed up to 250 mg/kg bw/day.
Mean combined (male and female) fetal body weights were 40.4, 38.5, 40.7 and 38.8 grams for the vehicle control, 30, 80 and 250 mg/kg bw/day groups, respectively.
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): no effects observed
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
no effects observed
Description (incidence and severity):
see Table 2: The male:female ratio was unaffected by treatment up to 250 mg/kg bw/day.
Changes in litter size and weights:
no effects observed
Description (incidence and severity):
see Table 2: There were no treatment related effects on litter size for any group.
Mean litter sizes were 8.4, 10.1, 9.2 and 9.2 fetuses per litter for the control, 30, 80 and 250 mg/kg bw/day groups, respectively.
External malformations:
no effects observed
Description (incidence and severity):
see Tables 4 and 5: The numbers of fetuses (litters) available for fetal morphological examination were 152 (18), 213 (21), 175 (18) and 183 (19) in the control, 30, 80 and 250 mg/kg bw/day groups, respectively. External and visceral examinations were done for all fetuses, soft tissue cephalic examination was done for approximately half of the fetuses for all groups, and skeletal examination was done for all fetuses of the control and high dose groups, initially. However, as the findings of 13th full ribs and caudal shift of pelvic girdle were noted at higher incidences at the high dose than in the control group, it was decided to extend the skeletal examinations to the low and mid dose groups.
There were no treatment related effects on external morphology following treatment up to 250 mg/kg.

Beside one fetus at the high dose (A078-06) with exencephaly, two late resorptions had a malformation. One fetus at 80 mg/kg (A047-12) had omphalocele and one at 250 mg/kg (A085-11) had anasarca. The single occurrence of these malformations do not indicate a relation to treatment and therefore were considered to be chance findings.
There were no external variations seen for any fetus in any group.
Description (incidence and severity):
see Tables 4 and 5:
The incidence of 13th full ribs in the control group was 27.8%, which is nearby the minimum historical control value of 26.8% (range 26.8% up to 71.4%). Therefore, this incidence was statistically significantly increased in all treatment groups. The increased incidences at 30 and 80 mg/kg (48.7% and 58.4% per litter, respectively) were considered not related to treatment, as the incidences remained within the historical control data and were not accompanied by an increased incidence of caudal shift of pelvic girdle (10.5% and 8.9% per litter, respectively compared with 9.0% per litter in the controls). The incidence at 250 mg/kg (74.3%), however, was higher than the historical control maximum value (71.4% per litter) and was accompanied by a statistically significantly increased incidence of caudal shift of pelvic girdle (33.0% versus control value 9.0% per litter). Therefore, the combination of these findings was considered treatment related. However, as these developmental variation findings were only seen at the highest dose leading to maternal toxicity and do not affect further development and viability of the fetuses, these findings were judged as not adverse.
Historical control 13th full ribs (% per litter in 26 studies in New Zealand White rabbits with in total 3934 control fetuses in 434 litters): mean = 48.7; min = 26.8; max = 71.4

The number of fetuses with fused sternebrae at 250 mg/kg/day was higher than in the other groups. This skeletal malformation was observed in 2 (2), 1 (1), 1 (1) and 5 (3) fetuses (litters) at an incidence of 1.8 %, 0.4%, 0.5% and 2.7% per litter in the control, 30, 80 and 250 mg/kg groups, respectively. The incidence at 250 mg/kg was just above the historical control maximum value (2.4% per litter), but given the absence of a dose response and statistical significance and because it is the most common skeletal malformation in the historical control database, it was not considered to be treatment related.

Remaining skeletal malformations occurred singly and as these occurred in different groups, they were not considered to be treatment related.
Visceral malformations:
no effects observed
Description (incidence and severity):
see Tables 4 and 5: There were no treatment related effects on visceral morphology following treatment up to 250 mg/kg.
Visceral malformations occurred in 2 (2), 2 (2), 2 (1) and 2 (2) fetuses (litters) in the control, 30, 80 and 250 mg/kg groups, respectively. Absence of a lung lobe was most frequently noted and it occurred in 0, 1, 2 and 2 fetuses in these respective groups. As a dose response for this finding could not be established and as it is also the most common visceral malformation in historical controls (highest incidence in historical control groups is three ), it was not considered to be treatment related.
The other visceral malformations occurred singly and therefore were considered to be chance findings.
All the variations noted, were not considered treatment related as they occurred infrequently, occurred at frequencies that were within the range of available historical control data or were observed in control fetuses only.
Dose descriptor:
NOAEL
Effect level:
250 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No toxicologically relevant adverse changes were noted in any of the developmental parameters investigated in this study.
Abnormalities:
no effects observed
Description (incidence and severity):
no adverse effects observed
Developmental effects observed:
no

Accuracy, homogeneity and stability of formulations were demonstrated by analyses. Stability of the test item was confirmed.

Table 1: SUMMARY OF MATERNAL SURVIVAL AND PREGNANCY STATUS

 Dose group     control     30 80         250
   No.  %  No.  %  No.  %  No.  %
 Females on study     22     22     22     22

 Females that aborted

or delivered

 0  0.0  0   0.0  0   0.0  0   0.0
 Females that died  0   0.0  0   0.0  0   0.0  0  0.0
 Females that aborted  0   0.0  0   0.0  0   0.0  0   0.0
 Nongravid  0   0.0  0   0.0  0   0.0  0   0.0
 Gravid  0   0.0  0   0.0  0   0.0    0.0
 Females that were euthanized  0   0.0  1   4.5  0   0.0  1   4.5
 Nongravid  0   0.0  0   0.0  0   0.0  0   0.0
 Gravid  0   0.0  1   100.0  0   0.0  1   100.0

 Females examined at

scheduled necropsy

 22  100.0  21  95.5  22  100.0  21  95 .5
 Nongravid  4   18.2  0  0.0  3  13.6  1  4.8
 Gravid  18  100.0  21  100.0  19  86.4  20  95.2
 with resorptions only  0  0  0  0.0  1  5.3  1  5.0
 with viable fetuses  18  100.0  21  100.0  18  94.7  19  95.0
 Total females gravid  18  81.8  22  100.0  19  86.4  21  95.0

Table 2: SUMMARY OF FETAL DATA AT SCHEDULED NECROPSY

                           
 Group  

Sex

 M

Sex 

F

 Viable

fetuses

 Dead

fetuses

Resorptions

 Early

 Resorptions

Late

 Post

implantation

loss

 Implantation

sites

 Corpora

lutea

 Pre

implantation

loss

Fetal

weights

in grams 

 No. of

gravid

females

 control  Total  83  60  152  0  7  5  12  164  175  12  NA  18
   Mean  4.6  3.8  8.4  0.0  0.4  0.3  0.7  9.1  9.7  0.7  40.4  
 30 mg/kg  Total  107  106  213  0  5  0  5  218  224  6  NA  21
   Mean  5.1  5.0  10.1  0.0  0.2  0.0  0.2  10.4  10.7  0.3  38.5  
 80 mg/kg  Total  88  87  175  0  10 (4)#  5  15  190  197  7  NA  19
  Mean   4.6  4.6  9.2  0.0  0.5  0.3  0.8  10.0  10.4  0.4  40.7  
 250 mg/kg  Total  88  95

 183

 0

 17 (6)#

 4

 21

 204

 221

 17

 NA

 20

 

 Mean

 4.4

 4.8

 9.2

 0.0

 0.9

 0.2

 1.1

 10.2

 11.1

 0.8

 38.8

 

None significantly different from control group

NA = NOT APPLICABLE

MEAN NUMBER OF VIABLE FETUSES, MEAN NUMBER OF IMPLANTATION SITES, MEAN NUMBER OF CORPORA LUTEA,

FETAL WEIGHTS COMPARED USING DUNNETT'S TEST

# substracting females No. 55 (80 mg/kg) and No. 87 (250 mg/kg) with early resorptions only the percentages shown in parenthesis result

Table 3: SUMMARY OF FETAL DATA AT SCHEDULED NECROPSY [% PER LITTER]

Group 

 0 MG/KG

 30 MG/KG

 80 MG/KG

 250 MG/KG

 Number of litters

 18

 21

19

 20

Corpora lutea

 

 

 

 

 Mean

 9.7

 10.7

 10.4

 11.1

 Implantation sites

 

 

 

 

 Mean

9.1

 10.4

 10.0

 10.2

 Viable fetuses (%)

 

 

 Mean

 93.9

 97.9

 90.6

 90.2

 Dead fetuses (%)

 

 

 

 Mean

 0.0

 0.0

 0.0

 0.0

 Early resorptions (%)

 

 

 

 

 Mean

 4.0

 2.1

 7.4#

 8.1#

 Late resorptions (%)

 

 

 

 Mean

 2.2

 0.0

 2.0

 1.7

 Total resorptions (%)

 

 

 

 

 Mean

 6.2

 2.1

 9.4#

 9.8#

 Pre-implantation loss (%)

 

 

 

 

 Mean

 6.6

 2.6

 3.8

 6.8

 Post-implantation loss (%)        
 Mean  6.2  2.1  9.4  9.8
 Males (%)        
 Mean  58.7  49.8  49.5  46.0
 Females (%)        
 Mean  41.3  50.2  50.5  54.0
 Male fetal weights (g)        
 Mean  40.2  38.5  40.5  54.0
 Female fetal weights (g)        
 Mean  39.4  38.5  40.8  38.5
 Combined fetal weights (g)        
 Mean  40.4  38.5  40.7  38.8

PROPORTIONAL (%) DATA COMPARED USING THE MANN-WHITNEY TEST

FETAL WEIGHTS COMPARED USING DUNNETT'S TEST

None significantly different from control group

# please take into consideration the explanation given in Table 2

Table 4: SUMMARY OF FETUSES AND LITTERS WITH MALFORMATIONS [ABSOLUTE NO. (% per litter)]

            Fetuses           Litters
 Dose group (mg/kg bw per day:  0  30  80  250  0  30  80  250
 Number examined  152  213  175  183  18  21  18  19
 EXTERNALLY: exencephaly  0  0  0  1  0  0  0  1 (0.5%)
 VISCERALLY: teratology of Fallot  0  1  0  0 0  1 (0.4%)  0  0
 lung- absent lobe (s)  0  1  2  2  0  1 (0.4%)  1 (0.9%)  2 (1.0%)
 right subclavian - originating from the pulmonary trunk  1  0  0  0  1 (0.7%)  0  0  0
vena cava - malpositioned  0  0  1  0  0  0  1 (0.4%)  0
 lung - abnormal lobation  1  0  0  0  1 (0.7%)  0  0  0

 SKELETALLY: vertebral anomaly with or without

associated rib anomaly

 1  0  0  0  1 (0.7%)  0  0  0
 sternebrae fused  2  1  1  5  2 (1.8%)  1 (0.4%)  1 (0.4%)  3 (2.7%)
 Vertebral centra anomaly  0  0  1  0  0  0  1 (0.5%)  0
 Total number with malformations                
 External:  0  0  0  1  0  0  0  1 (0.5%)
 Soft tissue:  2  2  2  2  2 (1.4%)  2 (0.8%)  1 (0.9%)  2 (1.0%)
 Skeletal:  2  1  2  6  2 (1.8%)  1 (0.4%)  1 (1.0%)  3 (3.1%)
 Combined:  3  3  4  9  3 (2.5%)  3 (1.3%)  2 (1.9%)  5 (4.7%)

Table 5: SUMMARY OF FETUSES AND LITTERS WITH VARIATIONS [ABSOLUTE NO. (% per litter)]

            Fetuses           Litters
 Dose group (mg/kg bw per day:  0  30  80  250  0  30  80  250
 Number examined  152  213  175  183  18  21  18  19

 SKELETALLY: 13th full rib(s)

 39  98  100  137  14 (27.8%)  20 (48.7%*)  17 (58.4%**)  19 (74.3%**)
 sternebra (e) malaligned (slight or moderate)  11  23  19  14  8 (7.6%)  10 (10.2%)  11 (10.1%)  9 (8.6%)
 metacarpal (s) and/or metatarsal (s) unossified  10  6  7  6  4 (5.0%)  3 (2.6%)  5 (3.6%)  4 (2.8%)
 sternebra (e) #5 and/or #6 unossified  29  53  51  28 11 (19.0%)  18 24.0%)  14 (27.9%)  14 (15.7%)
 pelvic girdle - caudal shift  10  22  18  61  4 (9.0%)  8 (10.5%)  8 (8.9%)  16 (33.0%**)
 13th rudimentary rib(s)  17  20  22  16  9 (11.7%)  12 (9.3%)  11 (11.4%)  12 (8.7%)
 sternebra (e) - branched  1  0  0  0  1 (0.7%)  0  0  0
 hyoid body and/or arches unossified 0  2  1  2  0  2 (0.9%)  1 (0.5%)  2 (1.0%)

* = Significantly different from the control group at 0.05

** = Significantly different from the control group at 0.01

Executive summary:

Triethyl phosphate was tested in a prenatal developmental toxicity study on 22 pregnant New Zealand rabbits per dose group following OECD TG 414. The test item was administered once daily by oral gavage from Days 6 to 28 post-coitum at doses of 0, 30, 80 and 250 mg/kg bw/day in water. The doses were chosen on the basis of a dose range finding study with doses of up to 500 mg/kg bw/day.

No maternal toxicity was observed up to and including 80 mg/kg bw/day. At 250 mg/kg bw/day, the majority of the high dose females showed treatment related calm behavior during several days up to the entire treatment period, ranging from slight to moderate severity. Reduced faeces production, varying in duration and severity, was noted in all groups, including the vehicle control group. However, as the incidence was increased in females treated at 250 mg/kg compared with the vehicle controls, low and mid dose groups, which could be correlated with the reduced food consumption in this group, it was therefore considered treatment related.

At 250 mg/kg, absolute and relative food consumption was reduced from start of treatment onwards up to Day 23 post-coitum. Concurrent body weight loss on Day 9 post-coitum (after 3 days of treatment) and reduced body weight gain between Day 13 and 23 post-coitum were also noted. From Day 23 and 26 post-coitum onwards absolute body weight and body weight gain were within the range of the control group, respectively. Body weight gain corrected for weight of the gravid uterus was unaffected by treatment up to 250 mg/kg bw/day.

The combination of calm behavior, ranging from slight to moderate severity, and reduced food consumption with concurrent body weight effects at 250 mg/kg was considered treatment related and adverse.

No adverse effects on development were observed in the 30, 80 and 250 mg/kg groups.

An increased incidence of non-adverse treatment related variations (i.e. 13th full ribs and caudal shift of the pelvic girdle) was noted at 250 mg/kg. The incidence of 13th full ribs was statistically significantly increased in all treatment groups. It should be noted that the control value was at the lower end of the historical control data. The increased incidences at 30 and 80 mg/kg bw/day (48.7% and 58.4% per litter, respectively) were considered not related to treatment, as the incidences remained within the historical control data and were not accompanied by an increased incidence of caudal shift of pelvic girdle (10.5% and 8.9% per litter, respectively compared with 9.0% per litter in the controls). The incidence at 250 mg/kg bw/day (74.3%), however, was higher than the historical control maximum value (71.4% per litter) and was accompanied by a statistically significantly increased incidence of caudal shift of pelvic girdle (33.0% versus control value 9.0% per litter). Therefore, the combination of these findings was considered treatment related. However, as these developmental variation findings do not affect further development and viability of the fetuses, these findings were not adverse. Furthermore, this finding was observed at a dose level resulting in maternal toxicity.

The number of early resorptions and consequently the post-implantation loss were increased in the 80 and 250 mg/kg bw/day groups compared with the concurrent controls. This increase was contributed to two individual females in each of these dose groups with resorptions only, which were considered incidental findings. In the remaining females the number of early resorptions and post implantation loss remained within the same range compared with the

concurrent controls. Taken together, the observed effects were considered not to be treatment related.

Based on the results in this prenatal developmental toxicity study the maternal No Observed Adverse Effect Level (NOAEL) for Triethyl phosphate was established as being 80 mg/kg bw/day based on calm behavior, reduced food consumption and transient body weight effects at 250 mg/kg bw/day. The developmental NOAEL was determined to be at least 250 mg/kg bw/day.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

In a developmental toxicity study following OECD 414 groups of 25 inseminated female Wistar rats per dose group were treated daily by gavage with TEP formulated in demineralised water from days 6 to day 15 p.c. in doses of 0, 25, 125 or 625 mg/kg body weight, respectively. The fetuses were delivered by cesarian section on day 20 of gestation.

The dams of the 625 mg/kg group revealed clinical signs like bloddy mouth, staggering gait and ventral posture. The staggering gait and the ventral posture are considered to be a sign of the narcotic efficacy of TEP.

Body weight gain (day 6 -15 p.c.), feed intake (day 6 -11p.c.) and accordingly the feces excretion were reduced in the 625 mg/kg group.

The intrauterine development was not affected by the treatment including external, visceral and skeletal examination of the fetuses. A teratogenic potential was not evident.

The NOAEL were:

Maternal toxicity: 125 mg/kg bw./day

Developmental toxicity: 625 mg/kg bw./day.

Triethyl phosphate was tested in a prenatal developmental toxicity study on 22 pregnant New Zealand rabbits per dose group following OECD TG 414. The test item was administered once daily by oral gavage from Days 6 to 28 post-coitum at doses of 0, 30, 80 and 250 mg/kg bw/day in water. The doses were chosen on the basis of a dose range finding study with doses of up to 500 mg/kg bw/day.

No maternal toxicity was observed up to and including 80 mg/kg bw/day. At 250 mg/kg bw/day, the majority of the high dose females showed treatment related calm behavior during several days up to the entire treatment period, ranging from slight to moderate severity. Reduced faeces production, varying in duration and severity, was noted in all groups, including the vehicle control group. However, as the incidence was increased in females treated at 250 mg/kg compared with the vehicle controls, low and mid dose groups, which could be correlated with the reduced food consumption in this group, it was therefore considered treatment related.

At 250 mg/kg, absolute and relative food consumption was reduced from start of treatment onwards up to Day 23 post-coitum. Concurrent body weight loss on Day 9 post-coitum (after 3 days of treatment) and reduced body weight gain between Day 13 and 23 post-coitum were also noted. From Day 23 and 26 post-coitum onwards absolute body weight and body weight gain were within the range of the control group, respectively. Body weight gain corrected for weight of the gravid uterus was unaffected by treatment up to 250 mg/kg bw/day.

The combination of calm behavior, ranging from slight to moderate severity, and reduced food consumption with concurrent body weight effects at 250 mg/kg was considered treatment related and adverse.

No adverse effects on development were observed in the 30, 80 and 250 mg/kg groups. An increased incidence of non-adverse treatment related variations (i.e. 13th full ribs and caudal shift of the pelvic girdle) was noted at 250 mg/kg.

Based on the results in this prenatal developmental toxicity study the maternal No Observed Adverse Effect Level (NOAEL) for Triethyl phosphate was established as being 80 mg/kg bw/day based on calm behavior, reduced food consumption and transient body weight effects at 250 mg/kg bw/day. The developmental NOAEL was determined to be at least 250 mg/kg bw/day.

Justification for classification or non-classification

Based on a weight of evidence evaluation of the available data for reproduction toxicity and Guideline-compliant developmental toxicity studies on rats and rabbits a classification for fertility and/or developmental toxicity according to EU Regulation 1272/2008 is not warranted.