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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
3. July 1984 - 18 April 1985
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well performed and documented study equivalent to OECD414.

Data source

Referenceopen allclose all

Reference Type:
study report
Title:
Unnamed
Year:
1987
Report Date:
1987
Reference Type:
publication
Title:
Unnamed
Year:
1992
Report Date:
1992

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
no data on food consumption and no. of corpaora lutea
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Type:
Constituent
Type:
Constituent
Details on test material:
Source: Aldrich Chemical Company
Lot: 1617HK
Purity: <99%

Test animals

Species:
rabbit
Strain:
New Zealand White
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Dutchland Inc., Denver, PA, USA
- Age at study initiation: approx. 6 months
- Weight at study initiation: 3100-4740 g
- Housing: singly in stainless steel cages with mesh flooring (min. 18"x24"x18" - max. 24"x24"x20)
- Diet (e.g. ad libitum): Purina Certified Rabbit Chow (5322), ad libitum
- Water (e.g. ad libitum): deionized/filtered water, ad libitum
- Acclimation period: 14 days

ENVIRONMENTAL CONDITIONS
- Humidity: 53%
- Temperature: 68°F
- Air changes (per hr): 12 - 14 times per hour
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
Artificially inseminated, timed-pregnant New Zealand White rabbits were dosed daily with Diglyme or vehicle on gestation day (gd) 6 though 19. Treatment wass administered by gavage. A dose volume of 3.0 mL/kg bw was used. The volume administered to each animal was adjusted according to daily body weight taken just prior to dosing on gd 6 through 19.

A. First preliminary study: Diglyme was administered at dose levels of 0, 100, 200, and 400 mg/kg bw/d (4 animals/dose level)
B. Second preliminary study: Diglyme was administered at dose levels of 0, 25, 50, 100, and 150 mg/kg bw/d (6 animals/dose level)
C. Main study dose levels: 0, 25, 50, 100, and 175 mg/kg bw/d at 15-25 animals/dose level)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Gas chromatography
Details on mating procedure:
atrificially inseminated
Duration of treatment / exposure:
gd 6 through 19 (14 days)
Frequency of treatment:
daily
Duration of test:
duration of treatment: 14 days
termination: gd 30
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
25 mg/kg bw/d
Basis:
actual ingested
Remarks:
Doses / Concentrations:
50 mg/kg bw/d
Basis:
actual ingested
Remarks:
Doses / Concentrations:
100 mg/kg bw/d
Basis:
actual ingested
Remarks:
Doses / Concentrations:
175 mg/kg bw/d
Basis:
actual ingested
No. of animals per sex per dose:
25 - 32
Control animals:
yes, concurrent vehicle
Details on study design:
On the basis of the observation of complete resorptions at dose levels of 200 mg/kg bw/d and above, an apparent increase in prenatal deaths at 25 mg/kg bw/d and above, maternal toxicity (weight loss) at 25 mg/kg bw/d, and icreased mortality of the dams at 100 mg/kg bw/d and above the dose levels for the main study were fixed.

Examinations

Maternal examinations:
Rabbits were weighed on gd 0 as well as daily on days 6 - 19 and prior to euthanasia on gd 30. Dams were observed daily during treatment for clinical signs of toxicity.
Ovaries and uterine content:
Following euthanasia, maternal liver weight and gravid uterine weight were measured. Uterine contents were evaluated for the number of implantation sites, resorptions, late fetal deaths (fetuses heavier than 10 g but displaying no vital signs) and live fetuses. the uterus was stained to reveal possible early resorptions when visible evidence of pregnancy was not apparent.
Fetal examinations:
Live fetuses were weighed and examined for exrernal abnormalities followed by evaluation for visceral malformations using a fresh tissue dissection technique. Half of the fetuses were decapitated after dissection and the heads were fixed in Bouin's solution for free-hand sectioning and axmaination. All fetal carcasses were cleared and stained with Alcian blue/Alizarin red S and examined for skeletal alterations.
Statistics:
Analyses were carried out using the general linear model procedure in the SAS software library (SAS Institute, Inc. 1985). Prior to analysis, an arcsine-square root transformation was performed on all litter-derived percentage data. Dose-response relationships for selected measures were evaluated using a test for linear trend. Analysis if variance (ANOVA) tests were used to determine whether significant dose effects, replicate effects, or dose x replicate interactions had occured. When ANOVA revealed significant differences among groups, then William's multiples comparison test and Dunnett's test were used to compare treated groups to the vehicle control group. Nominal scale measures analyzed by a test for linear trend on proportions and a chi square test for independence among treatment groups. When chi square revealed significant (p<0.05) differences among groups, then a one-tailed Fisher's exact probability test was used for pairwise comparisons between each Diglyme treated group and the vehicle control group.
Indices:
no data
Historical control data:
no data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes. Remark: increased mortality

Details on maternal toxic effects:
A clearcut maternal toxicity was evident only at the highest dose level (175 mg/kg bw/d). From 75 to 100% of the bred females in the various groups were pregnant. There was an increase in treatment-related maternal mortality at the highest dose level ( 15 vs. 4% in controls). Clinical signs were limited to a decreaed fecal output at the high dose level. There was a loss of weight during the days of chemical treatment at dose levels of 50 mg/kg bw/d and above, with the difference from control statistically significant at each of these dose levels.
A decrease in weight of the gravid uterus was observed that was statistically significant at the two highest dose levels (100 and 175 mg/kg bw/d). The body weight gain, corrected for gravid uterine weight, did not differ from that of the control group in any of the dose groups.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
50 mg/kg bw/day
Basis for effect level:
other: maternal toxicity
Dose descriptor:
NOEL
Effect level:
25 mg/kg bw/day
Basis for effect level:
other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes. Remark: adverse fetal effects

Details on embryotoxic / teratogenic effects:
At necropsy, all groups were similar in the number of implantations and the percentage preimplantational loss . There was however, a significant increase in prenatal mortality at the two highest dose levels (100 and 175 mg/kg bw/d). This loss was duee largely to the total resorption of 2 of 21 litters at 100 mg/kg bw/d and 5 of 17 litters at 175 mg/kg bw/d. There was a significant decreasing trend in fetal body weight but no group mean was significantly different from that of the controls. There was no evidence of a sex difference in eihter of these parameters - live fetuses/litter of fetal body weight. In contrast, female pups tended to have more malformations than males, with percentage of malformed fetuses per litter being significantly increased at both 100 and 175 mg/kg bw/d among female pups and only at the highest dose level among males. The malformations observed were diverse, being identified primarily in the visceral and skeletal structures. The two most frequently observed malformations were fused ribs in 17% (13/77) and hydronephosis in 23% (18/77) of high-dose fetuses. In addition, 19% of the high-dose fetuses exhibited clubbing of the fore- and hindlimbs, a condition that was classified as an anatomical variation in the present study, but for which the incidence increased with dose. The percentage of adeversely affected (includes resorptions, late fetal death and malformed fetuses) implants/litter was significantly increased above control at dose levels of 50 mg/kg bw/d and above.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
Exposure of New Zealand white rabbits to Diethylene glycol dimethyl ether at 25 mg/kg bw/d during gd 6 through 19 produced no adverse developmental effects. Doses of 50 mg/kg bw/d and above were associated with resorptions, late fetal death and malformed fetuses. The NOAEL (maternal) is considered to be 50 mg/kg bw/d.
Executive summary:

Diethylene glycol dimethyl ether (0, 25, 50, 100, or 175 mg/kg bw/d) were administered by gavage in distilled water to timed-pregnant New Zealand white rabbits (15 -25 dams/group) during gd 6 -19. Treated females were euthanized on gd 30, uterine contents were examined, and live fetuses were examined for morphological alterations. Evidence of maternal toxicity, per se, was observed only at 175 mg/kg bw/d with 15% mortality among treated females compared to 4% among controls. No significant maternal toxicity was observed in the 25 mg7kg bw/d group, and only minimal maternal toxicity (decreased maternal weight gain during treatment) was observed at 50 and 100 mg/kg bw/d compared to vehicle group.The NOEL (developmental) was 25 mg/kg bw/d, the NOAEL (maternal) 50 mg/kg bw/d. The incidences of prenatal mortality and malformed live fetuses were significantly above controls at 100 and 175 mg/kg bw/d. Malformations observed most frequently included fusion of ribs to each other and hydronephrosis; clubbing of the limbs without underlying bone deformities, a variation, was also observed.