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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
two-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference
Reference Type:
publication
Title:
Reproductive Toxicity of Triethylene Glycol and Its Diacetate and Dimethyl Ether Derivatives in a Continuous Breeding Protocol in Swiss-CD-1 Mice.
Author:
Bossert, N.L., Reel, J.R., Lawton, D., George, J.D., Lamb, J.C.
Year:
1992
Bibliographic source:
Fundamental and Applied Toxicology 18, 602-608

Materials and methods

Principles of method if other than guideline:
The study was conducted under the NTP Program's RACB protocol, the details of which have been published previously.
Triethylene glycol and two of its derivatives were evaluated for reproductive toxicity in a continuous breeding protocol with Swiss CD-1 mice. Triethylene glycol (TEG: 0, 0.3, 1.5, and 3%), triethylene glycol diacetate (TGD: 0, 0.75, 1.5, and 3%), and triethylene glycol dimethyl ether (TGDME: 0, 0.25, 0.5, and 1%) were administered in drinking water to breeding pairs (20 pairs per treatment group, 40 control pairs) during a 98-day cohabitation period. Reproductive function was assessed by the number of litters per pair, live pups per litter, proportion of pups born alive, and pup weight.
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid

Test animals

Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 6 weeks
- Housing: Throughout these studies, all animals were housed in solid-bottom polypropylene or polycarbonate cages with Ab-Sorb-Dri bedding. Male and female mice were group-housed by sex during quarantine and for the 1-week premating period. Subsequently, the animals were housed individually or as breeding pairs.
- Diet: Ground rodent chow (NIH-07)
- Water: deionized filtered water, ad libitum
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: 21 ± 0.5 °C
- Photoperiod (hrs dark / hrs light): 14/10

Administration / exposure

Route of administration:
oral: drinking water
Vehicle:
water
Details on exposure:
The treatment solutions for each test compound were independently formulated by mixing the test compound (w/v) directly into different proportions of distilled water. An aliquot of each formulation of each chemical in the drinking water and the control water and bulk chemical were sent to Midwest Research Institute at 6-week intervals for confirmation of dose levels and certification of the stability of the bulk chemical.
Details on mating procedure:
The test substance was administered in drinking water to breeding pairs (20 pairs per treatment group, 40 control pairs) during a 98-day cohabitation period.
Duration of treatment / exposure:
beginning 1 week before mating of the F0-generation until end of lactation period of the F2-generation
Frequency of treatment:
continuously
Details on study schedule:
Reproductive function was assessed by the number of litters per pair, live pups per litter, proportion of pups born alive, and pup weight.
Doses / concentrationsopen allclose all
Dose / conc.:
590 mg/kg bw/day (nominal)
Remarks:
0.3%
Dose / conc.:
3 300 mg/kg bw/day (nominal)
Remarks:
1.5%
Dose / conc.:
6 780 mg/kg bw/day (nominal)
Remarks:
3%
No. of animals per sex per dose:
- 20 animals per sex per dose group
- 40 animals per sex in the control group
Control animals:
yes, concurrent no treatment
Details on study design:
This study consists of 4 tasks:
Task 1 - dose-setting study
Task 2 - continuous breeding phase
Task 3 - crossover mating trial used to determine the affected sex when a positive effect on fertility is detected in Task 2
Task 4 - assesses the reproductive performance of the offspring from Task 2 breeding pairs
On the basis of the reduced body weight gain and increased mortality (12.5%) in the 5% test group, exposure levels of 0, 0.3, 1.5 and 3% TEG were selected for this study.

Examinations

Parental animals: Observations and examinations:
Body weight, kidney weight, liver weight, mortality, food consumption, water consumption, clinical signs.
Oestrous cyclicity (parental animals):
Estrous cycle length
Sperm parameters (parental animals):
Sperm concentration, motility, and morphology
Litter observations:
Pup growth to weaning, mortality
Postmortem examinations (parental animals):
Litters/pair, live pups/litter, cumulative days to litter, absolute testes/epididymis weight, sex accessory gland weight, epidid. sperm parameters.
Statistics:
Statistical analysis was performed. The level of significance for all tests was set at p<0.05.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, non-treatment-related
Description (incidence):
During Task 2, a total of 6 animals died - 2 females in the control, 1 male and 1 female in the 1.5% test group and 2 females in the 3% test group. The random distribution of deaths across treatment groups suggests that they were not treatment-related.
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
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
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed
Description (incidence and severity):
TEG during Task 2 had no effect on fertility or reproductive performance as indicated by the proportion of pairs able to produce at least 1 litter, number of litters produced per pair, number of live pups per litter or proportion of pups born alive.

Details on results (P0)

Since TEG exerted minimal effects on reproductive performance in the Task 2 parental mice (P generation), the effect of TEG on 2 -generation fertility was assessed. The exposure was continued and the final Task 2 litters (F1), of the control and 3% TEG groups were reared to maturity (74 +/- 10 days) and then these F1 offspring were mated to non-siblings from the same treatment group.

Effect levels (P0)

Dose descriptor:
NOAEL
Effect level:
6 780 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: overall effects

Target system / organ toxicity (P0)

Critical effects observed:
no

Results: P1 (second parental generation)

General toxicity (P1)

Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality:
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
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
no effects observed
Other effects:
no effects observed

Reproductive function / performance (P1)

Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed

Effect levels (P1)

Dose descriptor:
NOAEL
Effect level:
6 780 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: overall effects

Target system / organ toxicity (P1)

Critical effects observed:
no

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:
effects observed, treatment-related
Description (incidence and severity):
Continuous exposure to 1.5 or 3% significantly reduced mean live pup weight compared to the corresponding weights in the 0 and and 0.3% test group
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
no effects observed
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:
effects observed, treatment-related
Description (incidence and severity):
TEG significantly increased liver weight in males and when organ weights were adjusted for body weight, 3% TEG significantly increased female liver weight compared to controls.
Gross pathological findings:
no effects observed
Histopathological findings:
not examined
Other effects:
no effects observed

Developmental neurotoxicity (F1)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not examined

Details on results (F1)

TEG had no adverse effects on the other reproductive parameters measured, including F1 litter size.
Necropsy of the F1 male offspring showed that the highest concentration had no effect on body weight, testis, epididymis, seminal vesicle, or prostate weight, epididymal sperm concentration, percentage motile sperm, or percentage morphologically abnormal sperm. Necropsy of the F1 females showed no change in body or liver weight. The weights of the brain, pituitary, ovary, oviduct, and uterus were similarly unaffected. In contrast, TEG significantly increased liver weight in males and when organ weights were adjusted for body weight, 3% TEG significantly increased female liver weight compared to controls.
Furthermore, similar to the P generation, continuous exposure of the F1 mice to 3% TEG affected neither the mating index nor the fertility index.

Effect levels (F1)

Generation:
F1
Remarks on result:
not determinable due to absence of adverse toxic effects

Target system / organ toxicity (F1)

Critical effects observed:
no

Results: F2 generation

General toxicity (F2)

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
Description (incidence and severity):
Mice from the final Task 2 litters were weighed at births and on day 21 and day 74 +/- 10, and no significant differences were observed.
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
no effects observed
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 examined
Other effects:
no effects observed

Developmental neurotoxicity (F2)

Behaviour (functional findings):
no effects observed

Developmental immunotoxicity (F2)

Developmental immunotoxicity:
not examined

Details on results (F2)

TEG had no adverse effects on the other reproductive parameters measured, including proportion of F2 pups born alive, sex of the F2 pups born alive, and adjusted F2 pup weight.

Effect levels (F2)

Generation:
F2
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

Any other information on results incl. tables

Effect of TEG on fertility and reproductive performance:

   0% TEG  0.3% TEG  1.5% TEG  3.0% TEG
 No. fertile/No. cohabited  37/37  19/20  18/18  18/18
 Litters/pair  4.8 +/- 0.1 (37)  4.8 +/-0.2 (19)  4.8 +/- 0.2 (18)  4.6 +/- 0.3 (18)
 Live pups/litter  11.7 +/- 0.4 (37)  12.2 +/- 0.5 (19)  11.7 +/- 0.6 (18)  10.9 +/- 0.7 (18)
 Proportions of pups born alive  0.96 +/- 0.02 (37)  0.98 +/-0.01 (19)  0.97 +/- 0.02 (18)  0.96 +/-0.03 (18)
 Live pup weight (g)  1.66 +/- 0.02 (37)  1.63 +/- 0.02 (19)  1.60 +/- 0.02 (18)*  1.59 +/- 0.02 (18)*

* Pairs of mice were cohabited and dosed with the appropoirate chemical for 14 weeks. Pairs were considered fertile if they produced one or more litters.

Effect of TEG on male body and organ weights and sperm parameters at necropsy (The 5th litter produced during Task 2 was allowed to grow until 74 +/- 10 days of age. They received either control or chemical treatment via lactation until weaning and then dosed with drinking water until necropsy at 95 +/- 10 days of age. Each value is the mean +/- SE of 20 mice. ND = parameter not determined.)

 Weight or sperm parameter  0 (control)  3%
 Body (g)  33.2 +/- 0.4  33.1 +/- 0.9
 Liver (g)  2.02 +/- 0.03  2.13 +/- 0.05*
 Kidneys/adrenals (g)  ND  ND
 Right testis (mg)  120 +/- 4  115 +/- 4
 Right epididymis (mg)  47 +/- 1  43 +/- 1
 Prostate (mg)  34 +/- 4  32 +/- 3
 Seminal vesicles (mg)  285 +/- 13  305 +/- 17
 Motile sperm (%)  52 +/- 7  54 +/- 5
 Abnormal sperm (%)  5.8 +/- 1.5  4.9 +/- 1.4
 Sperm concentration**  700 +/- 35  719 +/-38

* significantly different (p<0.05) from the control group

** No. sperm x 10(3)/mg caudal tissue

Effect of TEG on female body and organ weights at necropsy (The 5th litter produced during Task 2 was allowed to grow until 74 +/- 10 days of age. They received either control or chemical treatment via lactation until weaning and then dosed drinking water until necropsy at 95 +/- 10 days of age. Each value is the mean +/- SE of 20 animals.)

 Weight (g)  0 (control)  3%
 Body  30.4 +/- 0.5  29.4 +/- 0.6
 Liver  2.01 +/- 0.05  2.02 +/- 0.07

Applicant's summary and conclusion