Reaction mass of 2-(3-ethylphenyl)oxirane and 2,2’-(1,3-phenylene)dioxirane and 2,2'-(1,4-phenylene)dioxirane

Endpoint summary

Description of key information

The study was designed to investigate the systemic toxicity and potential adverse effects of the test material on reproduction (including offspring development) and complies with the recommendations of the OECD Guidelines for Testing of Chemicals No. 422 “Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test” (adopted 22 March 1996).
This study was also designed to comply with Commission Regulation (EC) No 440/2008 of 30 May 2008 laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH).
The oral administration of Reaction mass of bis(epoxyethyl) benzene and (ethylphenyl) oxirane to rats by gavage, at dose levels of 200, 100 and 50 mg/kg/day, resulted in treatment-related effects at 200 and 100 mg/kg/day characterized by hyperkeratosis, ulceration/erosion and inflammation/abscesses of the forestomach resulting from local irritation at the site of contact during gavage dosing .  No such effects were detected at 50 mg/kg/day. Other than local irritation in the stomach there was no evidence of toxicity at any treatment level. Based on the data the 'No Observed Effect Level' (NOEL) for local (site of contact) irritation is 50 mg/kg/day and in the absence of any other toxicological effects the  the 'No Observed Effect Level' (NOEL) for systemic toxicity was considered to be 200 mg/kg/day.
The submission substance was found to be non-toxic during a 28-day repeat dose oral exposure study in the rat.
Repeat dose studies via the dermal and inhalation routes of exposure were not conducted on the basis of a lack of exposure to the submission substance.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Dose descriptor:

NOAEL

200 mg/kg bw/day

Study duration:

subacute

Species:

rat

Additional information

SUMMARY

Introduction.

The study was designed to investigate the systemic toxicity and potential adverse effects of the test material on reproduction (including offspring development) and complies with the recommendations of the OECD Guidelines for Testing of Chemicals No. 422 “Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test” (adopted 22 March 1996).

This study was also designed to comply with Commission Regulation (EC) No 440/2008 of 30 May 2008 laying down test methods pursuant to Regulation (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 material was administered by gavage to three groups, each of ten male and ten female Wistar Han™:HsdRccHan™:WIST strain rats, for up to fifty-four consecutive days (including a two week maturation phase, pairing, gestation and early lactation for females), at dose levels of 50, 100 and 200 mg/kg/day. A control group of ten males and ten females was dosed with vehicle alone (Arachis oil BP).

Clinical signs, behavioural assessments, bodyweight development, food and water consumption were monitored during the study. Haematology and blood chemistry were evaluated at termination on five selected males and females from each dose group. 

Pairing of animals within each dose group was undertaken on a one male: one female basis within each treatment group on Day 15 of the study, with females subsequently being allowed to litter and rear their offspring to Day 5 of lactation.

During the lactation phase, daily clinical observations were performed on all surviving offspring, together with litter size and offspring weights and assessment of surface righting reflex.

Extensive functional observations were performed on five selected males from each dose group after the completion of the mating phase, and for five selected parental females from each dose group on Day 4 post partum.

Males were terminated on Day 43, followed by the termination of all surviving females and offspring on Day 5post partum. All animals were subjected to a gross necropsy examination and histopathological evaluation of selected tissues was performed.

Results.

Mortality.One female treated with 200 mg/kg/day was found dead on Day 5. There were no further unscheduled deaths during the study.

Clinical Observations.Animals of either sex from all treatment groups showed episodes of increased salivation immediately post or one hour post dosing throughout the treatment period.

Behavioural Assessment.There were no treatment-related changes in the behavioural parameters measured.

Functional Performance Tests.There were no treatment-related changes in functional performance.

Sensory Reactivity Assessments.There were no treatment-related changes in sensory reactivity.

Bodyweight.Animals of either sex treated with 200 mg/kg/day showed actual bodyweight losses during Week 1 of treatment. Males from this treatment group continued to show a reduction in bodyweight gain during Week 2. Females treated with 200 mg/kg/day showed actual bodyweight losses during the first week of treatment.

No such effects were detected in animals of either sex treated with 100 or 50 mg/kg/day.

Food Consumption.No adverse effect on food consumption was detected. Food efficiency was however reduced for males treated with 200 mg/kg/day during the first two weeks of treatment and for females from this treatment group during the first week of treatment. 

No such effects in food efficiency were detected in animals of either sex treated with 100 or 50 mg/kg/day.

Water Consumption.No intergroup differences were detected.

Haematology.No toxicologically significant effects were detected in the haematological parameters measured.

Blood Chemistry.No toxicologically significant effects were detected in the blood chemical parameters measured.

Reproductive Performance:

Mating and Fertility.There were no treatment-related effects on mating or conception rates for treated animals.

One female treated with 50 mg/kg/day was found to be non-pregnant. One control and two females treated with 200 mg/kg/day failed to show any positive evidence of mating but subsequently gave birth to live young.

Gestation Length.There were no differences in gestation lengths. The distribution for treated females was comparable to controls.

Litter Responses:

Offspring Litter Size and Viability.Of the litters born, litter size at birth and subsequently on Days 1 and 4post partumwere comparable to controls.

Offspring Growth and Development.Litter weights at Day 4post partumwere reduced in females treated with 200 mg/kg/day.

No such effects were detected in litters from females treated with 100 or 50 mg/kg/day.

Litter observations.No clinically observable signs of toxicity were detected for offspring from all treatment groups.

Organ Weights.No toxicologically significant effects were detected in the organ weights measured.

Necropsy.No toxicologically significant effects were detected.

Histopathology.The following treatment-related effects were detected:

STOMACH:Hyperkeratosis of the forestomach was evident in animals of either sex treated with 200 and 100 mg/kg/day. Ulceration was also noted in one male and two females treated with 200 mg/kg/day. Further changes in the forestomach were identified as erosion in one female treated with 200 or 100 mg/kg/day, abscesses in the muscular layer in one male treated with 200 mg/kg/day and inflammation in the muscular layer in one male treated with 100 mg/kg/day and one female treated with 200 mg/kg/day.

Discussion

The oral administration of Reaction mass of bis(epoxyethyl) benzene and (ethylphenyl) oxirane to rats for a period of forty-two days for males and up to fifty-four days for females (including two weeks pre-mating, gestation and early lactation period) at dose levels of up to 200 mg/kg/day resulted in treatment-related effects at 200 and 100 mg/kg/day.

Clinically observable signs identified as increased salivation were observed during the daily clinical observations in all treatment groups. Treatment related microscopic findings representing a local irritant effect were confined to the stomach at 200 and 100 mg/kg/day and examination revealed hyperkeratosis, ulceration/erosion and inflammation/abscesses of the forestomach. Observations of this nature are commonly observed following the oral administration of an unpalatable or slightly irritant test material formulation. The microscopic gastric changes would support the possibility of irritation but such irritation must have been slight since there were no visible signs of gastric irritancy in these animals at necropsy. 

There were no toxicologically significant effects observed during the weekly open field arena observations, the haematological parameters measured or the blood chemical parameters measured. Macroscopic findings or organ weight data did not reveal any effects considered to be attributable to treatment.

No toxicologically significant effects in the reproductive parameters were observed. Excluding the three females treated with 200 mg/kg/day that showed inconclusive individual isolated effects, treated and control females showed comparable number of litters at termination on Day 5 post partumand no treatment-related effects were observed for offspring growth or development.

This study was ranked as Relaibility 1 according to the Klimisch et al scale, as it was conducted in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of relevant results.

A repeat dose dermal toxicity study was not conducted on the submisson substance as dermal contact during formulation and use is unlikely, and physicochemical and toxicological properties do not suggest a significant rate of absorption through the skin.

Testing by the inhalation route of exposure is considered in appropriate as exposure to humans via inhalation is considered unlikely, as there is no possibility of exposure to aerosols, particles or droplets of an inhalable size.

Conclusion

The oral administration of Reaction mass of bis(epoxyethyl) benzene and (ethylphenyl) oxirane to rats by gavage, at dose levels of 200, 100 and 50 mg/kg/day, resulted in treatment-related effects at 200 and 100 mg/kg/day characterized by hyperkeratosis, ulceration/erosion and inflammation/abscesses of the forestomach resulting from local irritation at the site of contact during gavage dosing . No such effects were detected at 50 mg/kg/day. Other than local irritation in the stomach there was no evidence of toxicity at any treatment level. Based on the data the 'No Observed Effect Level' (NOEL) for local (site of contact) irritation is 50 mg/kg/day and in the absence of any other toxicological effects the the 'No Observed Effect Level' (NOEL) for systemic toxicity was considered to be 200 mg/kg/day.

Justification for classification or non-classification

The submission substance did not meet the criteria for classification as toxic or harmful by the oral route of exposure during a 28 -day repeat dose toxicity study in the rat.