2-(2-ethoxyethoxy)-2-methylpropane

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / 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:

2015

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-(2-ethoxyethoxy)-2-methylpropane

EC Number:

257-196-8

EC Name:

2-(2-ethoxyethoxy)-2-methylpropane

Cas Number:

51422-54-9

Molecular formula:

C8H18O2

IUPAC Name:

2-(2-ethoxyethoxy)-2-methylpropane

Test material form:

other: liquid

Details on test material:

Name of test substance: 2-(2-ethoxyethoxy)-2-methylpropane
Test substance No.: 13/0109-2
Batch identification: 0012428678
CAS No.: 51422-54-9
Purity: NMR: 98.5 g/100 g
GC: > 99.9 area-%
water: 0.02 g/100 g
Homogeneity: The test substance was homogeneous by visual inspection.
Date of production: 01 Jun 2014
Physical state/ appearance: Liquid / colorless, clear
Storage conditions: Room temperature
Storage stability: Expiry date: 01 Jun 2016
The stability of the test substance under storage conditions over the test period was guaranteed by the sponsor, and the sponsor holds this responsibility.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Administration / exposure

Route of administration:

inhalation: vapour

Type of inhalation exposure (if applicable):

whole body

Vehicle:

other: conditioned air: about 50% ± 20% relative humidity, 22°C ± 2°C

Details on mating procedure:

In general, each of the male and female animals was mated overnight in a 1:1 ratio for a maximum of 2 weeks. Throughout the mating period, each female animal was paired with a predetermined male animal from the same test group.

The animals were paired by placing the female in the cage of the male mating partner from about 15:00-16.00 h until 06.00-07.00 h of the following morning. A vaginal smear was prepared after each mating and examined for the presence of sperm. If sperm was detected, pairing of the animals was discontinued. The day on which sperm was detected was denoted gestation day (GD) 0 and the following day "GD 1".

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

6h/day, males: 32 days and females: 57 days

Frequency of treatment:

daily

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
75, 250, and 750 mg/m3
Basis:

Doses / concentrations 2

Remarks:

Doses / Concentrations:
81.1, 243.3, and 726.0 mg/m3
Basis:

No. of animals per sex per dose:

10

Control animals:

yes

Results and discussion

Results: P0 (first parental generation)

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Description (incidence and severity):

male animals
For nearly all F0 parental males, which were placed with females to generate F1 pups, copulation was confirmed. Copulation was not confirmed for control male No. 6 paired with control female No. 106. Thus, the male mating index was 90% in the control and 100% in the low-, mid- and high-concentration groups. Fertility was proven for most of the F0 parental maleswithin the scheduled mating interval for F1 litter. One control male (No. 6), one low-concentration male (No. 11, test group 1, 75 mg/m³) and one mid-concentration male (No. 30, test group 2, 250 mg/m³) did not generate F1 pups. Thus, the male fertility index ranged between 90% and 100% without showing any relation to dosing. This reflects the normal range of biological variation inherent in the strain of rats used for this study. The apparently infertile male rats of the control (No. 6) and mid concentration group (No. 30, test group 2, 250 mg/m³) did not show relevant gross lesions or microscopic findings. The male animal No. 11 revealed a moderate reduction in the size of the left testis and epididymis, with a moderate tubular atrophy in the testis and a moderate oligospermia of the ipsilateral epididymis with additional cellular debris.

female animals
The female mating index calculated after the mating period for F1 litter was 90% in test group 0 and 100% in test groups 1-3. The mean duration until sperm was detected (GD 0) varied between 2.3 and 2.9 days without any relation to dosing. All female rats delivered pups or had implants in utero with the following exceptions:
Control female No. 106 (mated with male No. 6) did not become pregnant
Low-concentration female No. 111 (mated with male No. 11) did not become pregnant
Mid-concentration female No. 130 (mated with male No. 30) did not become pregnant
The fertility index varied between 90% (test groups 1 and 2) and 100% (test groups 0 and 3). These values reflect the normal range of biological variation inherent in the strain of rats used for this study. The non-pregnant female animal No. 130 showed a severe dilation of the uterus with cloudy fluid content. The apparently infertile female No. 106 (control group) and female No. 111 (test group 1, 75 mg/m³) did not show gross lesions or microscopic findings.
The mean duration of gestation was similar in all test groups (i.e. between 22.0 and 22.7 days). The gestation index was 100% in test groups 0, 1, and 3 and 88.9% in test group 2. These values reflect the normal range of biological variation inherent in the strain of rats used for this study. Implantation was not affected by the treatment since the mean number of implantation sites was comparable between all test substance-treated groups and the control, taking normal biological variation into account (11.4 / 11.2 / 9.4 and 11.4 implants/dam in test groups 0-3, respectively). Furthermore, there were no indications for any test substance-induced intrauterine embryo-/fetolethality since the post-implantation loss did not show any significant differences between the groups, and the mean number of F1 pups delivered per dam remained unaffected (11.1 / 10.4 / 10.4 and 11.2 pups/dam in test groups 0-3, respectively). The rate of liveborn pups was also not affected by the test substance, as indicated by live birth indices of 98.0% / 95.7% / 98.8% and 100% in test groups 0-3, respectively. Moreover, the number of stillborn pups was not significantly different between the test groups. All values are well covered by the historical control range.

Effect levels (P0)

Dose descriptor:

NOAEC

Effect level:

750 mg/m³ air

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Other effects:

not examined

Effect levels (F1)

Dose descriptor:

NOAEC

Generation:

F1

Effect level:

750 mg/m³ air (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

mortality

body weight and weight gain

gross pathology

Overall reproductive toxicity

Reproductive effects observed:

no

Applicant's summary and conclusion

Conclusions:

2-(2-ethoxyethoxy)-2-methylpropane did not adversely impact the reproduction of these rats, nor did treatment impact delivery and pup viability. Furthermore, none of the F1 generation pups showed any evidence of developmental toxicity in response to 2-(2-ethoxyethoxy)-2-methylpropane.

Executive summary:

During the exposure period, the target concentrations were met well and weremaintained as constant and stable as could be provided with the presented generation techniques in the concentration range tested.

Three pairs did not produce litter: one pair in the control group (No. 6 and 106), one pair in the test group 1 (No. 11 and 111) and one pair in the test group 2 (No. 30 and 130). Whereas no pathological findings were observed in sexual organs in the control group animals No. 6 and 106, histological findings were noted in one female (No. 130, test group 2, 250 mg/m³) and one male rat (No. 11, test group 1, 75 mg/m³). There was no concentration-response relationship, and the fertility was within the historical control range. Thus, no toxicologically relevant reproductive including fertility or developmental differences were observed between animals exposed to 75, 250 and 750 mg/m³ 2-(2-ethoxyethoxy)-2-methylpropane and controls. These concentrations of 2-(2-ethoxyethoxy)-2-methylpropane did not adversely impact the reproduction of these rats, nor did treatment impact delivery and pup viability. Furthermore, none of the F1 generation pups showed any evidence of developmental toxicity in response to 2-(2-ethoxyethoxy)-2-methylpropane.