2-(2-methoxyethoxy)ethanol

Toxicity to reproduction

Administrative data

Endpoint:

two-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1986

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Comparable to a guideline study. Rationale for using a read across substance is included in overall remarks section.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1984

Report date:

1984

Reference 2

Reference Type:

publication

Title:

Reproductive effects of diethylene glycol and diethylene glycol monoethyl ether in Swiss CD-1 mice assessed by a continuous breeding protocol

Author:

Williams J et al

Year:

1990

Bibliographic source:

Fundament Appl Toxicol 14, 622-625

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

other: NTP Fertility assessment by continuous breeding

Deviations:

no

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Deviations:

yes

Remarks:

P generation no organ weights, sperm parameters or oestrous cycle included; P animals slightly older than recommended at first exposure;

GLP compliance:

no

Remarks:

but full quality control auditing procedure used.

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-(2-ethoxyethoxy)ethanol

EC Number:

203-919-7

EC Name:

2-(2-ethoxyethoxy)ethanol

Cas Number:

111-90-0

Molecular formula:

C6H14O3

IUPAC Name:

2-(2-ethoxyethoxy)ethanol

Details on test material:

The test material was confirmed to be > 99% pure.

Test animals

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animals were 6 weeks old upon receipt and were quarantined for 2 weeks. During this period, 2 females and 2 males were killed and their serum was analyzed for 11 viruses. All tests were negative.
Mice were allowed free access to food and water.
They were randomly assigned to groups by body weight.
Eleven-week old mice were allocated into 4 treatment groups.

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on exposure:

no additional data

Details on mating procedure:

Parental: During premating exposure sexes housed separately (5/cage), females and males from the same dose group were then paired, housed one breeding pair per cage, and cohabitated for 98 days. The pairs were separated and the male and female mice were housed individually and exposed for an additional 3 weeks.
F1: After weaning F1 animals were continuously treated, and paired with nonsiblings from the same dose group at 74 +/- 10 days. These animals were cohabitated either for 1 week or until a copulatory plug was detected.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stock solutions of test material were analyzed for concentration at approximately 6-week intervals. They were found to be within 99-104% of target levels.

Duration of treatment / exposure:

premating exposure period: 1 week
mating exposure: 14 weeks
postmating exposure: 3 weeks
Total exposure: 126 days

Frequency of treatment:

continuous

Details on study schedule:

- F1 parental animals not mated until 74+/-10 days after selected from the F1 litters.
- Selection of parents from F1 generation when pups were 21 days of age.
- Age at mating of the mated animals in the study: 9-12 weeks

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 0.25, 1.25, and 2.5% w/v
Basis:
nominal in water

No. of animals per sex per dose:

40/sex for untreated controls and 20/sex in each of the following dose groups: 0.25, 1.25, and 2.5% w/v.

Control animals:

yes, concurrent vehicle

Details on study design:

An initial dose finding study was performed in which 8 animals/sex were exposed to 0, 1, 2, 3, 4 and 5% in the drinking water for 14 days. Doses chosen for use in the reproductive toxicity study were a dose that produced no effects, a dose that produced minimal toxicity, and a high dose that reduced body weight by approximately 10%.

Positive control:

none

Examinations

Parental animals: Observations and examinations:

Water consumption, parental body weights (time was not specified), mortality and clinical signs of toxicity of parents were evaluated.

Oestrous cyclicity (parental animals):

not examined

Sperm parameters (parental animals):

not examined

Litter observations:

The day of delivery of each litter, the number of litters per breeding pair, the number and percentage of fertile pairs, the number, percentage and sex of live pups per litter, and the mean body weights of live offspring were recorded.

Postmortem examinations (parental animals):

Because reproductive effects were not observed during the 126-day exposure period, the F0 parents were not necropsied.

Postmortem examinations (offspring):

The fifth or final litters from mice treated with 0% or 2.5% DEGEE were reared and weaned at Day 21 (all others were euthanized).
The F1 parents were euthanized and necropsied. Body, liver, brain and pituitary weights were recorded. Selected reproductive tissues from males (left testis with epididymis attached, right testis, right epididymis, prostate and seminal vesicles) and females (ovary with oviduct attached, and uterus) were weighed, fixed and embedded in paraffin, stained and evaluated by light microscopy. The sperm concentration, percentage of motile sperm, and percentage of abnormal sperm in the right cauda epididymis also were evaluated.

Statistics:

The Cochran-Armitage test was used to evaluate any dose-related trends in fertility. The cumulative days between litters were assessed by William's test. Pairwise comparisons were made using Fisher's exact test. A
Kruskal-Wallis analysis of variance on ranks was used to compare the number of litters per breeding pair and the number and sex of live pups among treatment groups. The Wilcoxon-Mann-Whitney U test was used to make intergroup pairwise comparisons. Ordered differences were tested for by Jonckheere's test. An analysis of covariance was performed to correct for the potential effect of the number of pups per litter on the average pup weight. Average organ weights adjusted for body weight were tested for equality by the covariance method used for pup body weights. Absolute organ weights were analyzed by the Kruskal-Wallis and Wilcoxon-Mann-Whitney U tests.
Analyses were performed on data for males and females separately and with both sexes combined. Pairs in which one or both partners died were excluded from the analysis. The criterion for significance was p < 0.05.

Reproductive indices:

Fertility Index (%) =( No. Fertile/No. cohabited )x100
Mating Index (%) = (No. with copulatory plugs/No. cohabited) x 100

Offspring viability indices:

proportion of pups born alive

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Mortality:

mortality observed, non-treatment-related

Description (incidence):

A total of 6 F0 animals died; one control male and female, one female in the 0.25 and 1.25% groups and two males in the high dose group.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

There were small decreases in the mean body weights of high dose males during weeks 1 and 5, which amounted to a 6% decrease compared to control.

Food consumption and compound intake (if feeding study):

no effects observed

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

effects observed, treatment-related

Description (incidence and severity):

Daily water consumption was monitored. During the first week, there was a significant (albeit slight) decrease in water consumption in high dose F0 males. However, at Week 13, the pairs given the high dose consumed more water than controls.

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Description (incidence and severity):

Examined in F1 generation.

Reproductive performance:

no effects observed

Description (incidence and severity):

Fertility index 100% at all doses

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

ca. 1.25 other: % in diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

water consumption and compound intake

Target system / organ toxicity (P0)

Critical effects observed:

no

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

mortality observed, non-treatment-related

Description (incidence and severity):

one female at 2.5% died during week 4.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

There was a 3% reduction in adjusted live pup weight for males from the 0.25% dose group, and a 5% reduction in this parameter for females in the high dose group. The effects on pup weights were considered by the investigators to have questionable biological significance since they were not dose-related in males and were small in females.

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

effects observed, treatment-related

Description (incidence and severity):

Sperm analyses on F1 males demonstrated a significant decrease (34%) in the percentage of motile sperm from the cauda epididymis of high dose males compared to controls. There was no effect on fertility or reproduction of the F1 generation mice despite this effect on sperm. Fertility index: 100% (at 0%) and 84% (at 2.5%).
See table in remarks.

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

The only significant changes observed in high dose F1 animals at necropsy were decreases in the absolute and relative brain weights of both sexes, and an increase in the absolute and relative liver weights of females and relative liver weight of males.

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Description (incidence and severity):

No histopathological changes were seen in any of the organs that were examined (including the testes).

Other effects:

no effects observed

Description (incidence and severity):

VIABILITY (OFFSPRING)
0.99+/-0.01, 0.97+/-, 0.98+/-, and 0.99+-/0.00, for 0, 0.25, 1.25 and 2.5% respectively.

Developmental neurotoxicity (F1)

Behaviour (functional findings):

not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:

not examined

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

ca. 1.25 other: % in diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Sperm motility only

Target system / organ toxicity (F1)

Critical effects observed:

not specified

Lowest effective dose / conc.:

2.5 other: % in diet

System:

male reproductive system

Organ:

other: testes (not specified) - sperm motility

Treatment related:

not specified

Dose response relationship:

not specified

Relevant for humans:

not specified

Results: F2 generation

General toxicity (F2)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

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

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

not specified

Developmental neurotoxicity (F2)

Behaviour (functional findings):

not examined

Developmental immunotoxicity (F2)

Developmental immunotoxicity:

not examined

Effect levels (F2)

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

ca. 2.5 other: % in diet

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Target system / organ toxicity (F2)

Critical effects observed:

no

Overall reproductive toxicity

Reproductive effects observed:

no

Relevant for humans:

yes

Any other information on results incl. tables

Assuming an average daily water consumption of 7 ml per 40-g mouse, drinking water concentrations of 0.25, 1.25 and 2.5% diethylene glycol monoethyl ether (DEGEE) represented average daily intakes of approximately 440, 2200 and 4400 mg DEGEE/kg/day, respectively.

Analyses pertaining to reproduction of F1 control and high dose males are listed in the following table. Corresponding data for F0 animals were not available. Values are presented as mean +/- SEM.

Parameter	Treatment (% DEGEE)
	0	2.5
Body weight (g)	34.7 +/- 0.7	34.2 +/- 1.1
Left testis/epididymis wt (mg)	174 +/- 7	172 +/- 6
Right testis wt (mg)	123+/-6	123+-6
Right epididymis wt (mg)	50 +/-1	49+/-2
Prostate wt (mg)	35+/-4	37+/-4
Seminal vesicle wt (mg)	329+/-18	350+/-16
Percentage motile sperm	64+/-5	42+/-6*
Sperm concentration (no. sperm x10E3/mg caudal epididymis)	627+/-47	614+/-42
Percentage abnormal sperm (excluding tailless)	2.3+/-0.3	3.5+/-0.7

* significantly different from 0% group at p<0.05

F0 animals were not necropsied. Therefore, sperm parameters, histology and gonad weights of these animals were not assessed.

Applicant's summary and conclusion

Conclusions:

Under the conditions of this reproductive study the test substance at doses as high as 2.5% (2200mg/kg/day) in the drinking water was not a reproductive toxicant deispite a decrease in sperm motility.

Executive summary:

In a two-generational study investigated the effects in reproduction and fertility of 0%, 0.25%, 1.25%, and 2.5% 2 -(2 -ethoxyethoxy)ethanol in drinking water. Male and female CD-1 mice were continuously treated for 1 week prior to mating and for a 14 week breeding period followed by a 21 day holding period when they were separated and housed individually. There were two deaths among the male F0 animals treated at high dose and small decreases in the mean body weights. The body weights of the F1 offspring exposed to 2.5% level were slightly depressed at birth, at weaning and at 74 +/-10 days. 2 -(2 -ethoxyethoxy)ethanol did not have adverse effects on fertility and reproductive performance despite a 34% decrease in caudal epididymal sperm motility in the F1 males at 2.5%. The highest dose also increased liver weight and decreased brain weight in both sexes of the F1 generation. The NOAEL for F0 and F1 generations can be established at 1.25% 2 -(2 -ethoxyethoxy)ethanol based on systemic and reproductive (sperm motility) effects respectively (equivalent to 2200mg/kg), and 2.5% for the F2 generation.

The substance 2 -(2 -ethoxyethoxy)ethanol is a very close analogue of the test substance used in the study and this result can be considered highly predictive of the toxicity of 2 -(2 -methoxyethoxy)ethanol.