1,2-diethoxypropane

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

5 August 1991 - 14 January 1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-guideline Chernoff/Kavlock preliminary screening developmental toxicity test

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Chernoff/Kavlock preliminary screening developmental toxicity test

Principles of method if other than guideline:

Ten female Sprague-Dawley rats were dosed from DG6-16 orally (gavage) at doses of 0, 1000 and 1600 mg/kg bw/day DEP. The vehicle was distilled water with 2% Tween 80. The positive control was ethylene glycol diethyl ether. They were then monitored throughout gestation, parturition and until Day 4 of lactation, for clinical signs of toxicity, body weight and food consumption changes, signs at necropsy, duration of gestation and overall pup survival, litter and pup weights.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,2-diethoxypropane

EC Number:

412-180-1

EC Name:

1,2-diethoxypropane

Cas Number:

10221-57-5

Molecular formula:

C7H16O2

IUPAC Name:

1,2-diethoxypropane

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: Synthetic Chemicals Limited, Four Ashes, West Midlands, England; 9059

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Stored in the dark at ambient temperature

Test animals

Species:

rat

Strain:

other: Sprague-Dawley (Charles River CD strain; outbred albino)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River UK Ltd, Margate, Kent, UK
- Age at study initiation: ca. 10 weeks
- Weight at study initiation: 280 g for males and ca 210 g for females
- Housing: Prior to mating, the females were housed 2 per cage in polypropylene cages measuring 42 x 27 x 20 cm, with stainless steel grid bottoms and mesh tops. A separate, stainless steel food hopper and a water bottle will be provided for each cage. The cages were suspended on racks, each containing 6 rows of 4 cages. On detection of mating, each female was re-housed in an individual solid bottomed cage of similar design. Sterilised white wood shavings were provided as bedding and white tissue paper was provided as nesting material. Males were housed singly in larger cages (58 x 38.5 x 20 em) of a similar design. The cages were suspended on racks, each containing 5 rows of 3 cages.
- Diet: Rat and Mouse Breeder Diet No.3 SQC Expanded, supplied bySpecial Diets Services Ltd, Stepfield, Witham, Essex, UK ad libitum (Appendix 1)
- Water: domestic mains water ad libitum (Appendix 2)
- Acclimation period: 4 days prior to pairing for mating.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20°C ± 2°C
- Humidity (%): 5O%± 15%
- Air changes (per hr): 15-20
- Photoperiod (hrs dark / hrs light): 12 hrs

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: Distilled water with 2% Tween 80

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The 2 materials (DEP and EGDE) were formulated as suspensions, the vehicle being distilled water containing 2% by volume of the surfactant Tween 80. Fresh suspensions were prepared daily, each concentration being prepared separately. The requisite quantity of vehicle was added to pre-weighed test material and mixed by inversion. The dosing suspensions were maintained in the animal room during dosing procedures using a magnetic stirrer.

Details on mating procedure:

Pairing was on the basis of 2 females to each male. For each female, cohabitation with a male was continuous until mating was detected. A vaginal lavage was examined each morning and the day of detection of sperm in the lavage, or of a copulatory plug in situ was considered to be Day 0 of gestation. A record was kept of the male which inseminated each female.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analyses for concentration, homogeneity and stability of dosing formulations were performed (Report No. 8246) prior to commencement of this study. Concentration and homogeneity were also analysed during this study. Triplicate 1 ml samples were taken from each test material and Control formulation on the first and eighth days of treatment. The results of the analyses conducted prior to this study, Report No. 8246, are presented in Appendix 3. These analyses demonstrated that adequately homogeneous formulations of both test materials could be prepared, and that those formulations were stable for 48 h when stored at 4 in the dark. The results of the analyses for concentration and homogeneity performed during this study are presented in Appendix 4. These results showed deviations from nominal concentration not exceeding 6%, indicating a satisfactory standard of accuracy in formulation.

Duration of treatment / exposure:

DG 6-16

Frequency of treatment:

Daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

1 600 mg/kg bw/day (nominal)

No. of animals per sex per dose:

10 females

Control animals:

yes, concurrent vehicle

other: Ethylene glycol diethyl ether (EGDE), a known developmental toxin.

Details on study design:

- Dose selection rationale: Doses were selected based on the results of the DRF study (Supporting, RL2, rat (DRF)/Shell, 1991/Toxicity to reproduction (Screening).001). Maternal toxicity was demonstrated at 1600 mg/kg bw/day DEP and at 1000 mg/kg bw/day EGDE, and to a lesser magnitude at 1000 mg/kg bw/day DEP.

Positive control:

Ethylene glycol diethyl ether (EGDE), a known developmental toxin was used. One group were allocated for EGDE administration. These animals were dosed once daily by gavage, with 1000 mg/kg bw/day from DG6-16.

Examinations

Parental animals: Observations and examinations:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule:All the animals were examined for reaction to treatment on each day. The nature, onset, duration and intensity of any signs were recorded. During the dosing period, the animals were. obServed at frequent intervals throughout the day, commencing approximately 5 min after dosing. In addition to the above, all the animals were checked for viability at the beginning of each day and again as late as possible on each day.

BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights were recorded on Days 0, 3, 6, 9, 13, 17 and 20 of gestation, and Days 1.and 4 of lactation (Day 0 of lactation = day of birth of the litter).

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes; The weight of food consumed by each mated female was recorded over the periods 0-3, 3-6, 6-9, 9-13, 13-17 and 17-20 of gestation.

Litter observations:

Litters of pups were weighed en masse on Days 1 and 4 of lactation. The pups were counted and examined for the presence of milk in the stomach, and for any externally visible abnormalities daily until termination.

Postmortem examinations (parental animals):

The dams and their litters were killed between Day 4 and 9 of lactation. Animals which did not deliver a litter were killed after their (theoretical) 24th day of gestation.

Premature Decedents
Adult animals were necropsied with a view to diagnosis, from macroscopic findings, of the cause of the animal's condition or cause of death. An external examination was followed by inspection of the cranial, thoracic and abdominal cavities. The uterus was examined to determine the status of pregnancy.

Scheduled Termination
Animals which did not deliver a litter were killed after their (theoretical) 24th day of gestation, to determine the status of their pregnancies. Necropsy, for other animals completing the study timecourse, was restricted to a count of the number of implantation sites in the uterus.

Postmortem examinations (offspring):

The dams and their litters were killed between Day 4 and 9 of lactation. Pups killed or found dead were discarded.

Statistics:

In evaluating and interpreting the data from this study it was not considered necessary to conduct any formal statistical analyses. Interpretation was based on inspection of the individual and group values.

Reproductive indices:

Gestation Index as %
Post implantation loss as %

Offspring viability indices:

Birth Index
Live Birth Index
Viability Index

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

The majority of animals in the 1,2 DEP and EGDE treated groups demonstrated clinical signs of toxicity after dosing. These signs included subdued behaviour, ataxia, increased salivation, piloerection and red staining from the nose and on the face. For both test materials, the duration of the clinical signs varied between animals, with the onset being between approximately 5 and IS min after dosing, and lasting between approximately one and 6 h. The intensity of the clinical signs also varied between animals within the same dose group. The subdued behaviour and ataxia observed.in the EGDE treated group tended to be slightly more pronounced than in the 1,2 DEP treated groups

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, non-treatment-related

Description (incidence):

There were 2 premature decedents at 1000 mg/kg bw/day. Necropsy of these animals revealed findings indicative of aspiration of dosing formulation and/or accidental damage during the dosing procedure.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

At 1600 mg/kg bw/day 1,2 DEP, there was a reduction in both mean body weight gain and food consumption over the treatment period, compared to the Negative Control. These effects were most pronounced over Days 6 to 9 of gestation, with a loss in body weight and a 32% reduction in food consumption over this period. At 1000 mg/kg bw/day DEP a similar pattern in body weight performance and food consumption to that seen at 1600 mg/kg bw/day 1,2 DEP was demonstrated. The magnitude of these effects however, was not as marked over Days 6 to 9 of gestation. A reduction in body weight performance and food consumption, comparable to that seen at 1000 mg/kg bw/day DEP, was demonstrated at 1000 mg/kg bw/day EGDE. The depression in body weight gain after Day 13 of gestation at 1000 mg/kg bw/day EGDE, was considered to have been a result of the resorbing litters. Body weight performance up to Day 4 of lactation at 1600 and 1000 mg/kg bw/day 1,2 DEP was similar to the Negative Control.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

At 1600 mg/kg bw/day 1,2 DEP, there was a reduction in both mean body weight gain and food consumption over the treatment period, compared to the Negative Control. These effects were most pronounced over Days 6 to 9 of gestation, with a loss in body weight and a 32% reduction in food consumption over this period. At 1000 mg/kg bw/day 1,2 DEP a similar pattern in body weight performance and food consumption to that seen at 1600 mg/kg bw/day 1,2 DEP was demonstrated. The magnitude of these effects however, was not as marked over Days 6 to 9 of gestation. A reduction in body weight performance and food consumption, comparable to that seen at 1000 mg/kg bw/day DEP, was demonstrated at 1000 mg/kg bw/day EGDE. The depression in body weight gain after Day 13 of gestation at 1000 mg/kg bw/day EGDE, was considered to have been a result of the resorbing litters. Body weight performance up to Day 4 of lactation at 1600 and 1000 mg/kg bw/day 1,2 DEP was similar to the Negative Control.

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:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Description (incidence and severity):

At 1000 mg/kg bw/day EGDE, all 9 pregnant animals resorbed their litters. Duration of gestation, gestation indices and overall pup survival were considered to have been unaffected by treatment with 1,2 DEP.

Effect levels (P0)

Dose descriptor:

LOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Sex:

female

Basis for effect level:

clinical signs

body weight and weight gain

Target system / organ toxicity (P0)

Critical effects observed:

no

Results: F1 generation

General toxicity (F1)

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

Occasional pups in all the groups with litters, showed minor changes (e.g. cold, bruised, agalactic) that are typical in these laboratories. No association with treatment was indicated

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Description (incidence and severity):

Overall pup survival were considered to have been unaffected by treatment with 1,2 DEP.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

At 1600 mg/kg bw/day 1,2 DEP, mean pup weight on Day 4 of lactation was slightly lower than the Negative Control. At 1000 mg/kg bw/day 1,2 DEP, mean pup weight was slightly reduced. This however, was a result of litter 19 which had a low mean pup weight and poor survival to Day 4 of lactation. Exclusion of this unrepresentative litter gave mean pup weight values which were similar to the Negative Control.

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

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not examined

Histopathological findings:

not examined

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:

1 000 mg/kg bw/day (nominal)

Sex:

male/female

Basis for effect level:

other: no effects

Target system / organ toxicity (F1)

Critical effects observed:

no

Overall reproductive toxicity

Reproductive effects observed:

no

Lowest effective dose / conc.:

1 000 mg/kg bw/day (nominal)

Treatment related:

no

Applicant's summary and conclusion

Conclusions:

In a Chernoff/Kavlock preliminary screening developmental toxicity test, maternal toxicity was demonstrated at the 2 doses tested (1600 and 1000 mg/kg bw/day DEP). Effects on the offspring of the 1,2 DEP treated animals were limited to a slight reduction in pup weight on Day 4 of lactation, at 1600 mg/kg bw/day.

Executive summary:

In a non-guideline Chernoff/Kavlock preliminary screening developmental toxicity test (7721), 1,2-Diethoxypropane in distilled water with 2% Tween 80 was administered to 10 female Sprague-Dawley rats/dose by gavage at dose levels of 0, 1000 or 1600 mg/kg bw/day from days 6 through 16 of gestation. Ethylene glycol diethyl ether (EGDE), a known developmental toxin was used as a positive control (1000 mg/kg bw/day).

Maternal toxicity was demonstrated at 1600 and 1000 mg/kg bw/day 1,2 DEP and at 1000 mg/kg bw/day EGDE, by a reduction in body weight and food consumption, and by clinical signs of toxicity. The toxicity observed at 1000 mg/kg bw/day 1,2 DEP and at 1000 mg/kg bw/day EGDE was of a comparable magnitude. Marked embryotoxicity was demonstrated at 1000 mg/kg bw/day EGDE with the 9 pregnant animals resorbing their litters. At 1000 mg/kg bw/day 1,2 DEP, however, the offspring were considered to have been unaffected. Effects on the offspring of the 1,2 DEP treated animals were limited to a slight reduction in pup weight on Day 4 of lactation, at 1600 mg/kg bw/day 1,2 DEP.

The maternal LOAEL was 1000 mg/kg bw.day. The NOAEL (offspring) was 1000 mg/kg bw/day.