p-tert-butylphenyl 1-(2,3-epoxy)propyl ether

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

p-tert-butylphenyl 1-(2,3-epoxy)propyl ether

EC Number:

221-453-2

EC Name:

p-tert-butylphenyl 1-(2,3-epoxy)propyl ether

Cas Number:

3101-60-8

Molecular formula:

C13H18O2

IUPAC Name:

2-[(4-tert-butylphenoxy)methyl]oxirane

Constituent 2

Reference substance name:

p-tert-butylphenyl-1-(2,3)-epoxypropyl ether

IUPAC Name:

p-tert-butylphenyl-1-(2,3)-epoxypropyl ether

Constituent 3

Reference substance name:

Oxirane, 2-((4-(1,1-dimethylethyl)phenoxy)methyl)-

IUPAC Name:

Oxirane, 2-((4-(1,1-dimethylethyl)phenoxy)methyl)-

Test material form:

other: Liquid at room temperature.

Details on test material:

As per IUCLID5 Sections 1.1. 1.2. and 4.1.

Specific details on test material used for the study:

Identification : p-tert-butylphenyl 1-(2,3-epoxy) propyl ether
Physical State/Appearance : Yellow liquid
Chemical Name : Oxirane, [[4-(1,1-dimethylethyl)phenoxy]methyl]-
Purity : 100%
Batch Number : DG4K20088
Date Received : 12 February 2016
Storage Conditions : Room temperature, in the dark
Expiry Date : 12 October 2017

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

Animal Information
A total of ninety-six time-mated female Sprague-Dawley Crl:CD (SD) IGS BR strain rats were obtained from Charles River (UK) Limited, Margate, Kent. Animals were delivered in two batches containing females prior to Day 3 of gestation. The day that positive evidence of mating was observed was designated Day 0 of gestation. On arrival the females weighed 189 to 289g.

Animal Care and Husbandry
The animals were housed individually in solid-floor polypropylene cages with stainless steel mesh lids furnished with softwood flakes (Datesand Ltd., Cheshire, UK). The animals were allowed free access to food and water. A pelleted diet (Rodent 2018C Teklad Global Certified Diet, Envigo RMS (UK) Limited, Oxon, UK) was used. Certificates of analysis of the batches of diet used are given in Annex 2. Mains drinking water was supplied from polycarbonate bottles attached to the cage. Environmental enrichment was provided in the form of wooden chew blocks and cardboard fun tunnels (Datesand Ltd., Cheshire, UK). The diet, drinking water, bedding and environmental enrichment was considered not to contain any contaminant at a level that might have affected the purpose or integrity of the study.

The animals were housed in a single air-conditioned room within the Envigo Research Limited, Shardlow, UK Barrier Maintained Rodent Facility. The rate of air exchange was at least fifteen air changes per hour and the low intensity fluorescent lighting was controlled to give twelve hours continuous light and twelve hours darkness. Environmental conditions were continuously monitored by a computerized system, and print-outs of hourly mean temperatures and humidity are included in the study records. The Study Plan target ranges for temperature and relative humidity were 22 ± 3 ºC and 50 ± 20% respectively there were no deviations from these targets.

The animals were randomly allocated to treatment groups using a randomization procedure based on stratified body weight to ensure similarity between the treatment groups. The animals were uniquely identified within the study by an ear punching system routinely used in these laboratories.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on exposure:

Animals were allocated to treatment groups as follows:

Treatment Dose Level Treatment Concentration Animal Numbers
Group (mg/kg bw/day) Volume (mL/kg) (mg/mL)

Control 0 4 0 24 (1-24)
Low 50 4 12.5 24 (25-48)
Intermediate 150 4 37.5 24 (49-72)
High 500 4 125 24 (73-96)

The numbers in parentheses ( ) show the individual animal numbers allocated to each treatment group.

The test item was administered daily, from Day 5 to Day 19 of gestation, by oral gavage. Control animals were treated in an identical manner with the vehicle alone.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Test Item Preparation and Analysis
For the purpose of the study the test item was prepared at the appropriate concentrations as a solution in Arachis Oil. The stability and homogeneity of the test item formulations were determined on Envigo study number: MG94KJ by Envigo Research Limited, Shardlow, UK Analytical Services. Results are given in Annex 1 and show the formulations to be stable for at least twenty days when stored at 4 °C in the dark. Bulk formulations were therefore prepared once and then divided into daily aliquots and stored at approximately 4 °C in the dark.

Samples were taken of each test item formulation and were analyzed for concentration of p-tert-butylphenyl 1-(2,3-epoxy) propyl ether at Envigo Analytical Laboratory, Shardlow. The method used for analysis of formulations and the results obtained are given in Annex 1. The results indicate that the prepared formulations were within ± 3% of the nominal concentration.

Duration of treatment / exposure:

Days 5 and 19 of gestation

Frequency of treatment:

Once per day

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

50 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

150 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

500 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

24

Control animals:

yes, concurrent vehicle

Details on study design:

The study was performed to investigate the effects of the test item on embryonic and fetal development, following repeated administration by gavage at dose levels 50, 150 and 500 mg/kg bw/day to the Sprague-Dawley Crl:CD® (SD) IGS BR strain rat during gestation, including the period of organogenesis.

The dose levels were chosen based on previous toxicity data which included a Preliminary Oral (Gavage) Pre-Natal Development Toxicity Study in the Rat (Envigo Study Number: YL76GQ). The oral route was selected as the most appropriate route of exposure, based on the physical properties of the test item, and the results of the study are believed to be of value in predicting the likely toxicity of the test item to man.

Examinations

Maternal examinations:

General Observations/Measurements
Clinical Observations
Following arrival, all animals were examined for overt signs of toxicity, ill-health or behavioral changes once daily during the gestation period. Additionally, during the dosing period, observations were recorded immediately before and soon after dosing and one hour post dosing. All observations were recorded.

Body Weight
Individual body weights were recorded on arrival, Day 3 (before the start of treatment) and on Days 5, 6, 7, 8, 11, 14 and 17 of gestation. Body weights were also recorded for surviving animals at terminal kill (Day 20).

Food Consumption
Food consumption was recorded for each surviving individual animal at Day 3, 5, 8, 11, 14, 17 and 20 of gestation.

Water Consumption
Water intake was observed daily by visual inspection of the water bottles for any overt changes.

Ovaries and uterine content:

All surviving animals were killed by carbon dioxide asphyxiation followed by cervical dislocation on Day 20 of gestation. All animals were subjected to a full external and internal examination and any macroscopic abnormalities were recorded. The ovaries and uteri of pregnant females were removed, examined and the following data recorded:

i) Number of corpora lutea
ii) Number, position and type of intrauterine implantation
iii) Fetal sex
iv) External fetal appearance
v) Fetal weight
vi) Placental weight
vii) Gravid uterus weight

The uteri of any apparently non-pregnant females were immersed in 0.5% ammonium polysulphide solution to reveal evidence of implantation.

Implantation types were divided into:

Early Death: No visible distinction between placental/decidual tissue and embryonic tissue
Late Death: Separate embryonic/fetal and placental tissue visible
Dead Fetus: A fetus that had died shortly before necropsy. These were included as late deaths for reporting purposes

All implantations and viable fetuses were numbered according to their intrauterine position as follows (as an example):

Left Horn Cervix Right Horn
L1 L2 L3 L4 L5 L6 L7 L8 R1 R2 R3 R4 R5 R6 R7 R8
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10 V11 V12 V13 V14 V15 V16

V = viable fetus

The fetuses were killed by subcutaneous injection of sodium pentobarbitone. Fetuses from each litter were divided into two groups and examined for skeletal alterations and soft tissue alterations. Alternate fetuses were identified using an indelible marker and placed in Bouin’s fixative. Fetuses were subsequently transferred to distilled water and examined for visceral anomalies under a low power binocular microscope and then stored in 10% Buffered Formalin. The remaining fetuses were identified using cardboard tags marked with chinagraph pencil and placed into 70% IMS in distilled water. The fetuses were subsequently eviscerated, processed and the skeletons stained with alizarin red S before being transferred to 50% glycerol for examination of skeletal development and anomalies and storage.

Statistics:

The following parameters were analyzed statistically, where appropriate, using the test methods outlined below:

Body weight change, food consumption and gravid uterus weight: Shapiro Wilk normality test and Bartlett’s test for homogeneity of variance and one way analysis of variance, followed by Dunnett’s multiple comparison test or, if unequal variances were observed, on alternative multiple comparison test.

All caesarean necropsy parameters and fetal parameters: Kruskal-Wallis non-parametric analysis of variance; and a subsequent pairwise analysis of control values against treated values using the Mann-Whitney ‘U’ test, where significance was seen.

Fetal evaluation parameters, including skeletal or visceral findings: Kruskal-Wallis nonparametric analysis of variance and Mann-Whitney ‘U’ test.

Probability values (p) are presented as follows:
p<0.001 ***
p<0.01 **
p<0.05 *
p≥0.05 (not significant)

Indices:

Data Evaluation
All data was summarized in tabular form, including reproductive indices. Group mean values were calculated to include data from all females with live fetuses on Day 20 of gestation. Values given in appendices may represent rounded values for presentation purposes. Group mean values were generally calculated using unrounded values therefore it is not always possible to calculate the exact group mean values from values presented in the appendices.

One high dose female animal (number 90) has been excluded from group mean values throughout the tables. This animal exhibited a compacted stomach at necropsy which is considered to have contributed to lower food consumption and therefore adversely affected the development of the fetuses. The values generated for this animal were atypical for the group as a whole and were considered not to be related to treatment with the test item. As the litter was standard unit of assessment, values were first calculated within the litter and group mean values represent the mean of these individual litter values.

Pre and Post Implantation Loss
Percentage pre-implantation loss was calculated as:
number of corpora lutea - number of implantations x 100/number of corpora lutea

Percentage post-implantation loss was calculated as:
number of implantations - number of live fetuses x 100/number of implantations

Sex Ratio
Sex ratio was calculated as:
% male fetuses (sex ratio) = Number of male fetuses x 100/Total number of fetuses

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Description (incidence and severity):

A summary incidence of daily clinical observations is given in Table 2. Individual data are presented in Appendix 1.

No clinical signs were noted in any surviving animal which were considered to be specifically related to systemic toxicity of the test item.

Instances of increased salivation were noted in all animals treated with 500 mg/kg bw/day which survived until the end of the treatment period. This observation was noted from Day 5 of treatment and generally persisted until the end of the treatment period. Increased salivation is commonly observed following the oral administration of an unpalatable or slightly irritant test item formulation and is generally considered to be of no toxicological importance. One animal (which exhibited atypical responses to treatment and fetal growth) treated with 500 mg/kg bw/day also exhibited staining around the snout which was apparent for one day only (Day 19). As this was an isolated incident noted in one animal only it was considered unlikely to be specifically related to systemic toxicity of the test item.

One control animal exhibited generalized fur loss from Day 10 until Day 20.

No clinical signs were apparent in any animal treated with 50 and 150 mg/kg bw/day.

Description (incidence):

One female treated with 500 mg/kg bw/day was killed in extremis on Day 8 of gestation due to the severity of clinical signs noted, these included hunched posture, pilo-erection, ataxia, dehydration, tip-toe gait and a stained ano-genital region. At necropsy, this animal exhibited red staining of the ano-genital region, enlarged and pale kidneys and an enlarged bladder with red colored contents.

There were no further unscheduled deaths.

Description (incidence and severity):

Group mean body weights and standard deviations are given in Table 3 and group mean values are presented graphically in Figure 1. Group mean body weight gains and adjusted body weights and standard deviations are given in Table 4 and Table 5. Individual data are given in Appendix 2, Appendix 3 and Appendix 4.

Females treated with 500 mg/kg bw/day showed general reductions in body weight gains throughout the treatment period (with the exceptions of Days 7 to 8 and 11 to 14 where gains were comparable to control), statistical significance was achieved from Days 5 to 6 (p<0.01), 8 to 11 (p<0.05) and 17 to 20 (p<0.001) of gestation. These reductions in body weight gain resulted in cumulative body weight gain being statistically significantly reduced (p<0.01 – p<0.001) throughout the entire treatment period, this resulted in overall body weight gain for these animals being 22% lower than control. Body weight gain when adjusted for gravid uterus weight was also statistically significantly reduced (p<0.001) (-42%) in these females.

No toxicologically significant effects were detected in females treated with 50 and 150 mg/kg bw/day.

Animals treated with 150 mg/kg bw/day exhibited a statistically significant reduction (p<0.05) in body weight gain from Days 11 to 14, however, at all other points during the study body weight gains were comparable to control. Overall body weight gain for these animals was only 6.1% lower than the control group animals and as such this effect was considered to be of no toxicological significance and likely to be due to normal biological variation.

Description (incidence and severity):

Group mean food consumptions are given in Table 6 and presented graphically in Figure 2. Individual data are given in Appendix 5.

General reductions in food consumption were evident in females treated with 500 mg/kg bw/day throughout the treatment period which achieved statistical significance from Days 5 to 8 (p<0.001), 8 to 11 (p<0.01) and 17 to 20 (p<0.001). No such effects of treatment were apparent in females treated with 50 and 150 mg/kg bw/day.

Description (incidence and severity):

Daily visual inspection of water bottles did not reveal any overt intergroup differences.

Description (incidence and severity):

A summary incidence of female necropsy findings is given in Table 7. Individual data are given in Appendix 6.

No macroscopic abnormalities considered to be related to treatment with the test item were noted in surviving animals treated with 50, 150 and 500 mg/kg bw/day.

One animal treated with 500 mg/kg bw/day exhibited compacted contents in the stomach, this was considered to be incidental and un-related to treatment with the test item and is likely to explain the very low fetal weights for this animal.

Maternal developmental toxicity

Details on maternal toxic effects:

Summary fetal data are given in Table 8. Individual data are given in Appendix 7 and Appendix 8.

There was no effect of maternal exposure to 50, 150 and 500 mg/kg bw/day of the test item on litter data, as assessed by numbers of implantations, in-utero offspring survival (as assessed by the mean numbers of early or late resorptions), live litter size, sex ratio and post implantation losses.

At 500 mg/kg bw/day, mean fetal weight for both sexes was statistically significantly lower (p<0.001) than control, resulting in statistically significantly lower (p<0.001) mean litter weights. Placental weights were comparable to control in these females.

No adverse effects on fetal, litter or placental weights were detected in females treated with 50 or 150 mg/kg bw/day.

Effect levels (maternal animals)

Key result

Dose descriptor:

NOEL

Effect level:

150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

body weight and weight gain

food consumption and compound intake

Results (fetuses)

Description (incidence and severity):

Neither the type, incidence nor distribution of external finding apparent for fetuses at Day 20 of gestation indicated an effect of maternal treatment on fetal development at 50, 150 or 500 mg/kg bw/day.

Description (incidence and severity):

Summary fetal skeletal findings are given in Table 11. Individual data are given in Appendix 11.

At 500 mg/kg bw/day, there was clear effect of treatment on a number of ossification parameters involving most regions of the skeleton, with the number of affected fetuses/litters increased compared with control and differences frequently attaining statistical significance (p<0.01 - p<0.001).

These parameters included incomplete ossification of the occipital (Supra Occipital) bones of the skull, incomplete ossification of the cervical (neural) arch and thoracic centrum, thoracic centrum not ossified, less than four caudal vertebrae ossified, ossification center associated with the first lumbar vertebrae, incomplete ossification of the sternebra, sternabra not ossified, bipartite ossification of the sternebra, incomplete ossification of the pubis and metacarpals not ossified. There was also a lower incidence of fetuses showing ossification of the ventral arch of vertebra 1 and ossification of one or more fore paw phalanges. The group mean incidences of these findings were outside of the ranges observed for the historical control values. A reduction in the number of fetuses exhibiting incomplete ossification of the hyoid bone of the skull was noted in these animals which achieved statistical significance (p<0.05), however, this was not regarded as evidence of adverse developmental toxicity as a decrease is closer to the expected range for this parameter. There was also no increase in the hyoid showing no ossification.

There was also an increase in the number of fetuses exhibiting 25/27 pre sacral vertebra, however, the percentage of fetuses exhibiting this was within the normal control data range and as such is considered not to be toxicologically significant.

At 150 mg/kg bw/day, a reduction in the incidence of fetuses/litters showing ossification of ventral arch of vertebra 1 was evident. However, group mean values were within the historical control range. This variation was seen in isolation of other developmental changes (in particular decreases in ossification) at this dose level and in the absence of an effect on mean fetal weight. Consequently, this was considered to be an isolated finding which was not regarded as evidence of adverse developmental toxicity. A reduction in the number of fetuses exhibiting incomplete ossification of the hyoid bone of the skull was noted in these animals which achieved statistical significance (p<0.05), however, this was not regarded as evidence of adverse developmental toxicity as a decrease is actually closer to the expected range for this parameter. Additionally there was no increase in the hyoid showing no ossification.

At 50 mg/kg bw/day, a statistically significant reduction (p<0.05) in the incidence of fetuses/litters showing a dumb belled shaped thoracic centrum. However, group mean values were within the historical control range. This variation was only seen in this treatment group and as no such effects were noted in animals treated with 150 or 500 mg/kg bw/day this was considered to be an isolated finding which was not regarded as evidence of adverse developmental toxicity as a decrease is closer to the expected range for this parameter.

Description (incidence and severity):

Summary fetal visceral findings are given in Table 10. Individual data are given in Appendix 10.

Visceral examinations of fetuses on Day 20 of gestation did not indicate any obvious effect of maternal treatment on fetal development at 50, 150 or 500 mg/kg bw/day.

Effect levels (fetuses)

Key result

Dose descriptor:

NOEL

Effect level:

150 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

skeletal malformations

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Key result

Developmental effects observed:

yes

Lowest effective dose / conc.:

500 mg/kg bw/day (actual dose received)

Treatment related:

yes

Relation to maternal toxicity:

developmental effects as a secondary non-specific consequence of maternal toxicity effects

Dose response relationship:

yes

Relevant for humans:

no

Applicant's summary and conclusion

Conclusions:

The oral (gavage) administration of p-tert-butylphenyl 1-(2,3-epoxy) propyl ether to pregnant rats from gestation Days 5 to 19, at dose levels of 50, 150 or 500 mg/kg bw/day was associated with lower maternal body weight gain during gestation and an effect on food consumption at 500 mg/kg bw/day. No similar effects were apparent at 50 or 150 mg/kg bw/day. Consequently, 150 mg/kg bw/day was considered to represent the No Observed Effect Level (NOEL) for the pregnant female.

In-utero survival of the developing conceptus was unaffected by maternal treatment with 500 mg/kg bw/day, although reduced fetal and placental weights and an increased incidence of skeletal findings indicated an adverse effect on fetal growth. No changes in the measured fetal parameters or embryofetal development were detected at 50 or 150 mg/kg bw/day. The ‘No Observed Effect Level’ (NOEL) for developmental toxicity was therefore considered to be 150 mg/kg bw/day.

Executive summary:

Introduction

The study was performed to investigate the effects of the test item on embryonic and fetal development following repeated administration by gavage to the pregnant female during gestation including the period of organogenesis.

The study was designed to comply with the following guidelines:

- US EPA Health Effects Test Guideline OPPTS 870.3700, ‘Prenatal Developmental Toxicity Study’ (August 1998)

- Japanese Ministry of Agriculture, Forestry and Fisheries Testing guidelines for Toxicology studies, 12 NohSan No 8147, (24 November 2000)

- OECD Guidelines for Testing of Chemicals, No 414, ‘Prenatal Developmental Toxicity Study’ (adopted 22 January 2001)

- Commission Regulation (EC) No 440/2008 of 30 May 2008 test methods pursuant to Regulations (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH)

Methods

The test item was administered by gavage to three groups each of twenty-four time mated Sprague-Dawley Crl:CD® (SD) IGS BR strain rats, between Days 5 and 19 of gestation inclusive at dose levels 50, 150, and 500 mg/kg bw/day. A further group of twenty-four time mated females was exposed to the vehicle only (Arachis Oil) over the same treatment period to serve as a control.

Clinical signs, body weight change, food and water consumptions were monitored during the study.

All females were terminated on Day 20 of gestation and subjected to gross necropsy including examination of the uterine contents. The number of corpora lutea, number, position and type of implantation, placental weights, fetal weight, sex and external and internal macroscopic appearance were recorded. Half of each litter were examined for detailed skeletal development and the remaining half were subjected to detailed visceral examination.

Results

Mortality

One female treated with 500 mg/kg bw/day was killed in extremis on Day 8 of gestation due to the severity of clinical signs noted; these included hunched posture, pilo-erection, ataxia, dehydration, tip-toe gait and a stained ano-genital region. At necropsy, this animal exhibited red staining of the ano genital region, enlarged and pale kidneys and an enlarged bladder with red colored contents. There were no further unscheduled deaths.

Clinical Observations

No clinical signs were noted in any surviving animal which were considered to be specifically related to systemic toxicity of the test item.

Body Weight

Females treated with 500 mg/kg bw/day showed general reductions in body weight gains throughout the treatment period; statistical significance was achieved from Days 5 to 6, 8 to 11 and 17 to 20 of gestation. These reductions in body weight gain resulted in the cumulative body weight gain being statistically significantly reduced throughout the entire treatment period. Body weight gain when adjusted for gravid uterus weight was also statistically significantly reduced (-42%) in these females.

No toxicologically significant effects were detected in females treated with 50 and 150 mg/kg bw/day.

Food Consumption

General reductions in food consumption were evident in females treated with 500 mg/kg bw/day throughout the treatment period which achieved statistical significance from Days 5 to 8, 8 to 11 and 17 to 20. No such effects of treatment were apparent in females treated with 50 and 150 mg/kg bw/day.

Water Consumption

No adverse effect on water consumption was detected.

Post Mortem Studies

No macroscopic abnormalities considered to be related to treatment with the test item were noted in surviving animals treated with 50, 150 and 500 mg/kg bw/day.

Litter Data and Litter Placental and Fetal Weights

The number of implantations and subsequent embryofetal survival were unaffected by maternal treatment at 50, 150 and 500 mg/kg bw/day. At 500 mg/kg bw/day, mean fetal weights for both sexes were lower than control, resulting in lower mean litter weights.

No toxicologically significant effects were detected at 50 and 150 mg/kg bw/day.

Fetal Examination

External Findings

Neither the type, incidence nor distribution of external finding apparent for fetuses at Day 20 of gestation indicated an effect of maternal treatment on fetal development at 50, 150 or 500 mg/kg bw/day.

Detailed Visceral Examinations

Visceral examinations of fetuses on Day 20 of gestation did not indicate any obvious effect of maternal treatment on fetal development at 50, 150 or 500 mg/kg bw/day.

Detailed Skeletal Examination

At 500 mg/kg bw/day, there was clear effect of treatment on a number of ossification parameters affecting most regions of the skeleton, with the number of fetuses/litters affected being increased compared with control (areas not ossified or showing incomplete ossification) decreases were also noted in the number of fetuses/litters showing ossified areas. No treatment-related adverse effects were detected in the type and incidence of skeletal findings in fetuses from females treated with 50 or 150 mg/kg bw/day.

Conclusion

The oral (gavage) administration of p-tert-butylphenyl 1-(2,3-epoxy) propyl ether to pregnant rats from gestation Days 5 to 19, at dose levels of 50, 150 or 500 mg/kg bw/day was associated with lower maternal body weight gain during gestation and an effect on food consumption at 500 mg/kg bw/day. No similar effects were apparent at 50 or 150 mg/kg bw/day. Consequently, 150 mg/kg bw/day was considered to represent the No Observed Effect Level (NOEL) for the pregnant female.

In-utero survival of the developing conceptus was unaffected by maternal treatment with 500 mg/kg bw/day, although reduced fetal and placental weights and an increased incidence of skeletal findings indicated an adverse effect on fetal growth. No changes in the measured fetal parameters or embryofetal development were detected at 50 or 150 mg/kg bw/day. The ‘No Observed Effect Level’ (NOEL) for developmental toxicity was therefore considered to be 150 mg/kg bw/day.