Dioctyl ether

Toxicity to reproduction

Administrative data

Endpoint:

one-generation reproductive toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Non GLP but peer reviewed publication. The restriction is also due to the use of read across approach: the study was performed not with DEGDEE but with DEGBE, a substance which like DEGDEE is part of the diethylene glycol monoalkyl and dialkyl ethers category. These substances have been demonstrated to be similar in structure, physical/chemical properties and toxicological profile.

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1985

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The solvent is dosed orally at 0, 250, 500, or 1000 mg/kg/day to male rats for 60 days prior to mating and to females from 14 days prior to mating until sacrificed on Day 13 or the weaning of the offspring. Untreated males were bred to treated females and vice versa. One-half of each group of females was sacrificed on Day 13 of gestation and the uterine contents were examined. The remaining females delivered their young and the offspring were followed to weaning.

GLP compliance:

no

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-(2-butoxyethoxy)ethanol

EC Number:

203-961-6

EC Name:

2-(2-butoxyethoxy)ethanol

Cas Number:

112-34-5

Molecular formula:

C8H18O3

IUPAC Name:

2-(2-butoxyethoxy)ethanol

Constituent 2

Reference substance name:

Diethylene Glycol Monobutyl Ether

IUPAC Name:

Diethylene Glycol Monobutyl Ether

Details on test material:

- Name of test material (as cited in study report): Diethylene glycol monobutyl ether (DGBE)
- Molecular formula (if other than submission substance): C8H18O3
- Molecular weight (if other than submission substance): 162
- Smiles notation (if other than submission substance): CCCCOCCOCCO
- InChl (if other than submission substance): InChI=1S/C8H18O3/c1-2-3-5-10-7-8-11-6-4-9/h9H,2-8H2,1H3
- Structural formula attached as image file (if other than submission substance): see Fig.
- Substance type: organic
- Physical state: liquid
- Analytical purity: 95 ± 2%

Test animals

Species:

rat

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River
- Age at study initiation: (P) 28 days (males), 70 days (Females)
- Weight at study initiation: (P) Males: 191 +- 12 g; Females: 237 +- 14 g; (Mean +- standard deviation)
- Fasting period before study: no
- Housing: Individually in suspended wire-mesh cages, except during mating, gestation and lactation
- Use of restrainers for preventing ingestion (if dermal): yes/no
- Diet (e.g. ad libitum): Purina Certified Rodent Chow 5002 ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 15 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 20 - 70
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12 /12

IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

VEHICLE
- Justification for use and choice of vehicle (if other than water):
- Concentration in vehicle:
- Amount of vehicle (if gavage): 5 mL/kg
- Lot/batch no. (if required):
- Purity:

Details on mating procedure:

- M/F ratio per cage: 1:1
- Length of cohabitation:
- Proof of pregnancy: copulatory plug or vaginal inspection for sperm referred to as day 0 of gestation
- After 10 days of unsuccessful pairing replacement of first male by another male with proven fertility.
- Further matings after two unsuccessful attempts: no
- After successful mating each pregnant female was caged (how): Individual plastic cage
- Any other deviations from standard protocol:

Analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Males: 60 days before mating until sacrifice
Females: 2 weeks before mating, until sacrifice at day 13 of gestation or until weaning of offspring

Frequency of treatment:

Daily

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 250, 500, 1000 mg/kg/day
Basis:
nominal conc.

No. of animals per sex per dose:

25

Control animals:

yes, concurrent vehicle

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: No
- Time schedule:
- Cage side observations checked in table [No.?] were included.

DETAILED CLINICAL OBSERVATIONS: No
- Time schedule:

BODY WEIGHT: Yes
- Time schedule for examinations: Males weekly until sacrifice, Females: selected for early sacrifice weighed on days 0, 7 & 13 of gestation
Females delivering: Day 0, 7, 13 & 20 of gestation, days 0, 7, 14 & 21 of lactation

Oestrous cyclicity (parental animals):

For animals sacrificed on day 13 of gestation, a uterine examination was performed: numbers of corpora lutea, implants, resorptions and viable embryos were recorded. Uteri of apparently non-gravid animals were placed in 10% ammonium sulphide solution to determine if they had become pregnant and early resorption had ocurred

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: yes
- If yes, maximum of 10 pups/litter (5/sex/litter as nearly as possible); excess pups were examined externally, killed and discarded.

PARAMETERS EXAMINED
The following parameters were examined in [F1] offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, physical or behavioural abnormalities

GROSS EXAMINATION OF DEAD PUPS:
yes, for external and internal abnormalities; possible cause of death was not determined for pups born or found dead

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals sacrificed at day 13 of gestation following completion of female examinations
- Maternal animals: One half of each group was randomly selected for sacrifice on Day 13 of gestation, other half sacrificed on Day 21 of lactation

Postmortem examinations (offspring):

SACRIFICE
- These animals were subjected to postmortem examinations (macroscopic and/or microscopic examination) as follows:

GROSS NECROPSY
- Gross necropsy consisted of internal examinations

Statistics:

All statistical analyses compared treated groups to the control group with a significance level of p <=0.05. The mean postimplantation loss in the
females sacrificed at 13 days and the pup survival and lactation indices at 4, 7, 14 and 21 days postpartum were compared by the Mann-Whitney U test as described by Siegel (1956) and Weil (1970) to determine the significance of the differences. The numbers of corpora lutea, implantations, and viable embryos in the animals sacrificed at 13 days, and the numbers of live births, and the various body weights were compared by analysis of variance,with Bartlett's test for homogeneity and the appropriate t test for equal or unequal variances, as described by Steel and Torrie (1960), using Dunnetts'(1964) multiple comparison tables. The fertility indices were compared using the x2 test with Yates' correction for 2X2 contingency tables and/or Fisher's exact probability test(Siegel, 1956).

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

not examined

Histopathological findings: non-neoplastic:

not examined

Other effects:

no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Effect levels (P0)

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No effects observed.

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Effect levels (F1)

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No effects obsereved

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

See table 1 below for results for male rats.

Table 1 The Effect Of Diethylene Glycol Monobutyl Ether On Fertility And Reproduction When Given

Orally To Male Rats For 60 Days Prior To Mating

	DGBE (mg/kg/day)^a
	0	250	500	1000
Mean ±SD body wt, time 0	191 ± 12	187 ±11	195 ± 12	188 ± 14
Mean ±SD body wt, Week 12	499 ± 47	510 ± 41	509 ± 54	474 ± 52
No. males/No. fertile males^b	25/24	25/23	25/22	22/22
	13-Day sacrifices of females
No, females/No. pregnant^c	12/12	13/12	12/10	12/12
Mean ± SD corpora lutea	16.1 ± 3.0	16.4 ± 1.6	15.8 ± 2.2	15.8± 2.1
Mean ± SD implants	14.3 ± 3.6	15.1 + 2.9	14.3 ± 3.3	15.1 ± 2.6
Mean ± SD resorptions	0.8 ± 0.8	0.7 ± 0.8	0.6 ± 1.0	1.5 ± 1.5
Mean ± SD viable embryos	13.5 ± 3.3	14.4 ± 2.8	13.7 ± 3.2	13.6 ± 2.9
	Natural birth females
No, females/No. pregnant	13/12	12/11	13/11	12/12
Mean ± SD live pups born	13.6 ± 1.7	13.2 ± 3.6	14.0 ± 1.9	12.2 ± 3.8
Mean ± SD dead pups born	0	0.3 ± 0.5	0.2 ± 0.6	0.1 ± 0.3
Mean ± SD pups at day 4^d	13.4 ± 1.7	12.8 ± 3.4	13.8 ± 2.0	12.0 ± 4.0
Mean ± SD pups at day 21	10 ± 0	9.4 ± 1.5	10 ± 0	8.8 ± 2.1
Mean ± SD pup wt
Day 0	6.0 ± 0.6	6.3 ± 0.5	6.1 ± 0.3	6.5 ± 0.8
Day 4	9.6 ± 1.3	10.0 ± 1.0	9.4 ± 0.7	10.3 ± 1.9
Day 14	29.9 ± 2.5	31.0+ 2.1	29.8 ± 2.1	32.0 ± 4.0
Day 21	48.2 ± 3.9	50.1 ± 2.9	49.0 ± 3.1	52.1 ± 6.0

^a Males only dosed with DGBE. Control males and females dosed with deioized water vehicle.

^b One male treated with 500 mg/kg and three males treated with 1000 mg/kg died between Weeks 5 and 10.

^c One untreated female in the group of males treated with 1000 mg/kg died.

^d Number of pups before reduction of the litters to 10

See table 2 below for table for female rats.

Applicant's summary and conclusion

Conclusions:

A fertility study in rats was undertaken to test the effects of diethylene glycol monobutyl ether. Rats were dosed at 0, 250, 500 or 1000 mg/kg/day.
The NOAEL for DEGBE for the toxicity to reproduction was found to be 1000 mg/kg/day by oral gavage in both parent and F1 rats .

Executive summary:

DEGDEE and DEGBE, which is in the above study tested for its reproductive toxicity in rats, are both part of the diethylene glycol monoalkyl and dialkyl ethers category described and evaluated in the document titled "Category Approach-Read across Bis(2 -ethoxyethyl)ether" (2013).

These substances have been demonstrated to be very similar in structure, physical/chemical properties and toxicological profile . Therefore, a read-across from DEGDEE to data obtained with DEGBE is scientifically justified.