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Toxicity to reproduction

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Administrative data

Endpoint:
two-generation reproductive toxicity
Remarks:
based on test type (migrated information)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Publication which meets generally accepted scientific standards. Non-guideline study conducted by NTP. Restrictions on reliability are mainly based on the limited information reported in the publication.

Data source

Reference
Reference Type:
publication
Title:
Reproductive Toxicity of Triethylene Glycol and Its Diacetate and Dimethyl Ether Derivates in a Continous Breeding Protocol in Swiss CD-1 Mice
Author:
Bossert et al.
Year:
1992
Bibliographic source:
Fundamental and Applied Toxicology 18:602-608

Materials and methods

Principles of method if other than guideline:
Task 1: initial dose-setting study
Task 2: continous breeding phase F0
Task 3: crossover mating trial if (only if altered reproductive outcome in F0)
Task 4: F1 mating to produce F2 generation
GLP compliance:
not specified
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate
EC Number:
203-846-0
EC Name:
2,2'-[ethane-1,2-diylbis(oxy)]bisethyl diacetate
Cas Number:
111-21-7
Molecular formula:
C10H18O6
IUPAC Name:
2-[2-(2-acetyloxyethoxy)ethoxy]ethyl acetate
Details on test material:
- Name of test material (as cited in study report): TGD, triethylene glycol diacetate
- Analytical purity: approximately 98%
- Purity test: assessed by Midwest Research Institute, using gas chromatographie
- Stability under test conditions: assessed by Midwest Research Institute, using gas chromatographie
- Supplier: CTC Organics

Test animals

Species:
mouse
Strain:
other: COBS Crl:CD-1(ICR)BR outbred Swiss albino mice (CD-1)
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles RIver Breeding Laboratories, Inc. (Kingston, NY)
Sera of two 6-week old mice each sex were evaluated for antibodies against 11 mouse viruses (Microbiological Associates, Inc., Bethesda, MD).
- Age at study initiation: (P) 8 wks
- Housing: in solid-bottom polypropylene or polycarbonate cages with Ab-Sorb-Dri bedding (Laboratory products, Inc., Garfield, NJ). Males and females were group-housed by sex during quarantine and for the 1-week premating period. Subsequently, the animals were housed individually or as breeding pairs. Cages were sanitised weekly using detergent and 82.22 °C (180 °F) water
- Diet (e.g. ad libitum): ground rodent chow (NIH-07), ad libitum
- Water (e.g. ad libitum): deionised/filtered water, ad libitum
- Acclimation period: 2 weeks (qurantine period)

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22.22 (70 ± 2 °F)
- Photoperiod (hrs dark / hrs light): 10/14

Administration / exposure

Route of administration:
oral: drinking water
Type of inhalation exposure (if applicable):
other: Not applicable.
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The test item was directly added to the destilled water in appropriate concentrations (w/v). Dosing solutions were found to be stable for at least 3 weeks when stored at room temperature in the dark. Nevertheless, all solutions were prepared fresh every 2 weeks and stored at room temperature protected from light prior to use.

VEHICLE
- Purity: The distilled water which was offered as drinking water and was used for the preparation of dosing solutions was controlled at 6-week intervals at Midwest Reserach Institute.
Details on mating procedure:
The study was conducted under the National Toxicology Program's RACB protocol.
- Task 2: P animals were kept as breeding pairs for a 98-day continous breeding phase.
- Task 3: a crossover mating trial was used to determine the affected sex when a positive effect on fertility was detected during Task 2.
- Task 4: F1 animals from Task 2 (control and 3% high dose group) were assessed for the reproductive performance

No further details are given in the publication.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
An aliquot of each formulation in the drinking water and the control water and bulk chemical were sent to the Midwest Reserach Institute at 6-week intervals for confirmation of dose levels and certification of of the stability of the bulk chemical. Reference aliquots were within 98-112% of target values.
Duration of treatment / exposure:
- Dose setting experiment: 2 weeks
- Main study: P animals received the test item via drinking water during a 98-day cohabitation period. The F1 was treated with the test itemfrom conception until 74 ± 10 days of age.
Frequency of treatment:
daily, 7 days/week
Details on study schedule:
No further details are given in the publication.
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0.625, 1.25, 2.5, 5, and 10% (w/v)
Basis:
nominal in water
During dose setting study (Task 1)
Remarks:
Doses / Concentrations:
0.75, 1.5, and 3% (w/v)
Basis:
nominal in water
During main study
Remarks:
Doses / Concentrations:
1,360, 2,740, 5,450 mg/kg bw/day
Basis:
actual ingested
average daily intake
No. of animals per sex per dose:
- control: 40 P males and females
- dose groups: 20 P males and females
Control animals:
other: Yes, plain drinking water
Details on study design:
- Dose selection rationale: An initial dose setting study was performed (Task 1).
Positive control:
No special positive control was included into the study. Nevertheless, triethylene glycol dimethyl ether (TGDME) was tested in the same study and exhibited toxic effects to the reproductive system at 1,470 mg/kg bw day.

Examinations

Parental animals: Observations and examinations:
DOSE SETTING STUDY:
- Mortality, clinical signs, body weight, and fluid consumption

CAGE SIDE OBSERVATIONS: Yes
- Cage side observations checked: physical appearence, mortality

BODY WEIGHT AND BODY WEIGHT GAIN: Yes

WATER CONSUMPTION AND COMPOUND INTAKE : Yes
- Compound intake was calculated on the basis of the average fluid consumption and the mean body weight data from the male mice.
Sperm parameters (parental animals):
Parameters examined in [F1] male parental generations:
testis weight, epididymis weight, prostate weight, seminal vesicles weight, sperm concentration (No sperm x 10³/mg caudal tissue), sperm motility, sperm morphology
Litter observations:
PARAMETERS EXAMINED
- The following parameters were examined in [F1] offspring:
number of litters per breeding pair, number of live pups per litter, proportion of pups born alive, live pup weight (on days 0, 4, 14, 21, and 74 ± 10)
- The following parameters were examined in [F2] offspring:
sex of F2 pups born alive, live F2 pup weight
Postmortem examinations (offspring):
SACRIFICE
- Male F1 animals (high dose group): all surviving animals at 95 ± 10 days of age.
- Maternal F1 animals (high dose group): all surviving animals at 95 ± 10 days of age. The fifth litter was allowed to grow until 74 ± 10 days of age.

ORGAN WEIGHTS
- The following organs of the male F1 animals (high dose group) were weighed: liver, kidney/adrenals, right testis, right epididymis, prostate, and seminal vesicles
- The following organ of the maternal F1 animals (high dose group) was weighed: liver, kidney/adrenals
Statistics:
Statistical analysis was performed as described in the RACB protocol (Lamb et al., (1985) Toxicol. Appl. Pharmacol. 81:100-112; NTP (1989) NTIS PB89152425/AS). The level of significance for all tests was set at p < 0.05.
Reproductive indices:
Proportion of matings or fertile pairs (F1)

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 specified
Histopathological findings: non-neoplastic:
not specified
Other effects:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
not specified
Reproductive performance:
no effects observed

Details on results (P0)

DOSE SETING EXPERIMENT
No mortality was observed in any of the dose groups. Body weight gain of the high dose animals was significantly reduced as compared to all other groups. No clinical signs were noted at any exposure level, nor did daily fluid consumption differ across groups.

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
No treatment related changes in physical appearence was observed in P animals.

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
No treatment related changes in body weight gain was observed in P animals.

TEST SUBSTANCE INTAKE (PARENTAL ANIMALS)
No treatment related changes in fluid consuption and test substance uptake was observed in P animals.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
Continous exposure to the test substance via drinking water had no effect on fertility or reproductive performance as measured by the ability of breeding pairs to produce one or more litters, the number of live pups per litter, proportion of pups born alive, and live pup weight.

Effect levels (P0)

Dose descriptor:
NOAEL
Effect level:
> 5 450 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: clinical signs; body weight gain; water consumption and compound intake; litter production; litter size; proportion of pups born alive; live pup weight

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Significant decrease in body weight of high dose offspring (F1) on days 14 and 21, reversible until 74 ± 10 days of age
Sexual maturation:
not specified
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
not specified
Histopathological findings:
not specified

Details on results (F1)

VIABILITY (OFFSPRING)
No effect on the number of live pups per litter (F1) was observed in any of the dose groups.

BODY WEIGHT (OFFSPRING)
No effect on the live pup body weight (F1) was obseerved in low and mid dose animals. F1 pups of the high dose group showed significantly decreased body weights on days 14 and 21, which was reversible until 74 ± 10 days of age.

ORGAN WEIGHTS (OFFSPRING)
Male F1 animals of the high dose group did not show effects on liver weights or reproductive organ weights. Combined kidney/adrenal weight was significantly increased in high-dose males. F1 females of the high dose group did not show effects on liver weights. The effect on the combined kidney/adrenal weight was only significant when organ weights adjusted to body weight.

OTHER FINDINGS (OFFSPRING)
No significant effects on sperm motility, concentration or morphology was observed in F1 males of the high dose group.

Effect levels (F1)

Dose descriptor:
NOAEL
Generation:
F1
Effect level:
> 5 450 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: body weight; organ weights (especially male reproductive organs); mating index; live birth index; litter weight; pup weight; sex ratio; sperm characterization;

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

Tab. 1: Effects of the test item on fertility and reproductive performance in mice (P) during continuous breeding*

Treatment group

No. fertile/No. cohabited

Litters/pair

Live pups/litter

Proportion of pups born alive

Live pup weight (g)

Control

38/39

4.8 ± 0.1

12.6 ± 0.3 (38)

0.99 ± 0.00 (38)

1.61 ± 0.01 (38)

0.75% test item

19/19

5.0 ± 0.1

12.9 ± 0.4 (19)

0.99 ± 0.00 (19)

1.62 ± 0.02 (19)

1.50% test item

20/20

4.8 ± 0.2

12.9 ± 0.5 (20)

0.99 ± 0.00 (20)

1.65 ± 0.02 (20)

3.00% test item

18/19

4.7 ± 0.2

12.8 ± 0.5 (18)

1.00 ± 0.00 (18)

1.59 ± 0.02 (18)

* Pairs of mice were cohabited and dosed with the appropriate chemical for 14 weeks. Pairs were considered fertile if they produced one or more litters, except for No. fertile/No. cohabited. Values represent means ± SE. Number in parentheses denotes number of fertile pairs providing the data.

Tab. 2: Effects of the test item on male body and organ weights and sperm parameters at necropsy*

 

Treatment group

Weight or sperm parameter

Control

3% test item

Body (g)

33.9 ± 0.4

34.8 ± 0.8

Liver (g)

2.11 ± 0.04

2.17 ± 0.07

Kidneys/adrenals (g)

0.74 ± 0.02

0.82 ± 0.03***

Right testis (mg)

131 ± 5

122 ± 6

Right epididymis (mg)

48 ± 1

48 ± 2

Prostate (mg)

43 ± 5

54 ± 7

Seminal vesicles (mg)

331 ± 13

374 ± 16

Motile sperm (%)

87 ± 4

89 ± 2

Abnormal sperm (%)

7.3 ± 0.8

10.2 ± 2.0

Sperm concentration**

509 ± 41

433 ± 41

* The fifth 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 mean ± SE of 20 animals.

** No. sperm x 10³/mg caudal tissue

*** significantly different from the control group

Tab. 3: Effect of the test item on female body and organ weight at necropsy*

 

Treatment group

Weight (g)

Control

3% test item

Body

30.9 ± 0.5

30.7 ± 0.5

Liver

1.93 ± 0.06

1.98 ± 0.06

* The fifth 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 mean ± SE of 20 animals.

Tab. 4: Body weights at various time points after birth of F1 offspring exposed to the test item

Age

Treatment group*

Males

Females

Control

3% test item

Control

3% test item

Birth (Day 0)

1.68 ± 0.02

1.65 ± 0.02

1.63 ± 0.02

1.62 ± 0.04

Day 4

2.99 ± 0.08

2.81 ± 0.12

2.90 ± 0.08

2.74 ± 0.13

Day 14

7.48 ± 0.27

6.42 ± 0.25 **

7.39± 0.27

6.27 ± 0.29**

Day 21

12.02 ± 0.58

9.40 ± 0.56

11.38 ± 0.41

9.05 ± 0.52**

Day 74 ± 10

33.67 ± 0.56

33.96 ± 0.67

28.12 ± 0.42

27.91 ± 0.59

* Values represent male or female pup weight (g) per litter (means ± SE). There were 33 control litters and 16 test item litters for days o, 4, 14, and 21. At day 21, 10 litters from the control group and the test groups were weaned and reared to sexual maturity.

** Significantly different from control fgroup (p < 0.05)

Applicant's summary and conclusion