1,2-dichloroethane

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Link to relevant study records

Reference

Endpoint:

two-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1982

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

Meets generally accepted scientific standards, limited documentation, acceptable for assessment, MTD not reached

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Deviations:

not specified

Principles of method if other than guideline:

Limitations included
- Dosing: 35 d premating dosing only. No exposure during pregnancy and lactation. No MTD reached: No toxic effect noted at any of the doses used. - Examination: Necropsy performed on pups, but no pathology and histopathology documented. No sperm parameters reported.

GLP compliance:

not specified

Limit test:

no

Species:

mouse

Strain:

ICR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Flow Laboratories, Dublin, VA, USA
- Age: 7 weeks old
- Housing: On sawdust bedding in polycarbonate cages
- Diet: Purina Rodent Laboratory Chow 501, ad libitum
- Water: drinking solution, ad libitum
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: 22-23 degree C
- Humidity: 40-60 %
- Photoperiod: 12 hours dark / 12 hours light

Males were housed singly; females were kept three per cage, except during parturition and lactation, when they were housed one per cage. Males and females were co-housed (1:3, respectively) for 7 days at each mating. Litters were weaned at 21 days of age.

Route of administration:

oral: drinking water

Vehicle:

other: 1% solution of Emulphor EL-620

Details on exposure:

The test substance was administered with the drinking water containing 1 % Emulphor EL-620 at 0.03, 0.09, and 0.29 mg/mL, designed to yield doses of 5, 15, or 50 mg/kg bw/d. No aversion to the vehicle or the test substance was observed. Fresh drinking water solutions were prepared twice daily. The highest dose was chosen to provide approx. 1/10 of the LD50.

Details on mating procedure:

Matings between siblings were avoided. Males and females were co-housed (1:3, respectively) for 7 days at each mating.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

No data on analytical verification of doses.

Duration of treatment / exposure:

Exposure period: none during pregnancy and lactation
Premating exposure period (males): 5 weeks (F0); 11 weeks (F1)
Premating exposure period (females): 5 weeks (F0); 11 weeks (F1)
Duration of test: 25 wk and 24 wk in F0 and F1B animals, resp.

Frequency of treatment:

daily

Details on study schedule:

After 35 days of treatment, F0-generation was mated to produce an F1A generation (10 males, 30 females). Two weeks after weaning of the offspring, the same adults were mated again to produce an F1B generation and subsequently an F1C generation applying the same mating regimen. The F1A generation was subjected to necropsy on postnatal day 21, i.e. after weaning, while F1B mice were mated after weaning (three wk) and a further 11 wk of treatment to produce F2A and, two wk after weaning of the F2A generation, F2B. The F2A generation was autopsied on postnatal day 21.

Remarks:

Doses / Concentrations:
ca. 0, 5, 15 or 50 mg/kg bw/d (30, 90 or 290 mg/L)
Basis:
nominal in water

No. of animals per sex per dose:

F0: 10 males and 30 females
F1: 10 males and 30 females

Control animals:

yes, concurrent no treatment

Details on study design:

no further details given

Positive control:

none

Parental animals: Observations and examinations:

Weekly body weight and twice-weekly fluid consumption data were collected for the F0 and F1B adult mice throughout the study. Mean body weights were analysed similarly. Adult percentage mortality was calculated at the termination of each generation (25 weeks of dosing for the F0; 24 for the F1B). Mice found moribund or sacrificed at the end of the study were necropsied.

Oestrous cyclicity (parental animals):

Weights of rats showing vaginal smears were recorded on days 0, 6, 14, and 21 of gestation. 

Sperm parameters (parental animals):

not investigated

Litter observations:

Twenty-one-day survival studies were performed on litters from F1 and F2 matings. Litter size was recorded on Days 0, 4, 7, 14, and 21. Litters were randomly culled to 10 pups each on day 4. Offspring were weighed collectively on days 7 and 14 and individually on day 21. All pups from each litter were sacrificed and necropsied at the conclusion of each 21-day survival study.

Postmortem examinations (parental animals):

Mice found moribund or sacrificed at the end of the study were necropsied.

Postmortem examinations (offspring):

All pups from each litter were sacrificed and necropsied at the conclusion of each 21-day survival study.

Statistics:

Group differences in body weight and fluid uptake were evaluated by Duncan's multiple range test. Adult reproductive performance was evaluated by fertility and gestation indices. Evaluation of litter data included Kruskal-Wallis test and Dunn's test. Level of significance chosen was always p<0.05.

Reproductive indices:

Adult reproductive performance was evaluated by calculation of fertility and gestation indices.

Offspring viability indices:

Viability and lactation indices were calculated.

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 examined

Other effects:

no effects observed

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Adult mice (F0 and F1B) showed no significant changes in water consumption, body weight or fertility index and gestation index (number of females with live litters/number of females pregnant). Mortalities were seen only in the F0 animals (2/10 m, 3/30 f) at the lowest dose, e.g. effect was not dose related. At scheduled necropsy (after week 24  or 25 of dosing), neither chemical- nor dose-related gross pathology was observed in either generation.

Dose descriptor:

NOAEL

Effect level:

ca. 50 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: No adverse reproduction effects up to highest dose used in the study.

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 specified

Gross pathological findings:

no effects observed

Histopathological findings:

not examined

Among the offspring of F0 and F1B animals (F1A, F1B, F2A), no significant changes were seen in mean litter size, mean post-natal body weights (measured on days 7, 14 and 21), or survival (measured on days 4 and 21). There was no evidence of dose-dependent gross pathology or congenital external,  visceral or skeletal malformations although no details or data were given.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

ca. 50 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: No adverse reproduction effects up to highest dose used in the study.

Dose descriptor:

NOAEL

Generation:

F2

Effect level:

ca. 50 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: No adverse reproduction effects up to highest dose used in the study.

Reproductive effects observed:

not specified

Dominant lethal screening:

Statistically significant effects in the ratio of dead to live fetuses were observed in both generations. However, these effects, which were both increases and decreases compared to controls, did not appear to be dose related.

Teratogenicity screening:

Maternal ingestion of the test compound produced no apparent adverse reproductive effects or increased incidence of fetal visceral or skeletal anomalies.

Conclusions:

There appeared to be no dose-dependent effects on fertility, gestation, viability, or lactation indices. Pup survival and weight gain were not adversely affected. 1,2 -dichlororethane failed to produce significant dominant lethal mutations or teratogenic effects in either of the two generations tested.

Executive summary:

A multigeneration reproduction study was modified to include screening for lethal and teratogenic effects of 1,2 -dichloroethane in drinking solution (Emulphor: deionized water, 1:99, v/v). Male and female (10 and 30/dose level, respectively) ICR Swiss mice received 1,2 -dichloroethane at concentrations of 0, 0.03, 0.09 or 0.29 mg/mL. These concentrations were designed to yield daily doses of 0, 5, 15 or 50 mg/kg bw/d. No taste aversion was evident. There appeared to be no dose-dependent effects on fertility, gestation, viability, or lactation indices. Pup survival and weight gain were not adversely affected. 1,2 -dichlororethane failed to produce significant dominant lethal mutations or terata in either of the two generations tested.

Effect on fertility: via oral route

Dose descriptor:

NOAEL

50 mg/kg bw/day

Effect on fertility: via inhalation route

Dose descriptor:

NOAEC

617 mg/m³

Additional information

In a 2-year “repeated dose one-generation study” with male and female rats fed 1,2 -dichloroethane in the diet at 250 and 500 mg/kg feed, no differences in parental fertility, litter data, and pup data (survival, body weights) compared to controls were seen during F0 -pregnancies from number 1 through 5. NOAELs for both parental and F1 reproductive effects were estimated to be the top dose in the range of 50 mg/kg bw/d, taking into account substance losses due to evaporation (Alumot et al., 1975). This result was confirmed by a similarly designed two-generation study in male and female ICR mice having received comparable doses of DCE in drinking water of 5 – 50 mg/kg bw/d for 5 weeks during premating of the F0 and 11 weeks of the F1 generation. Adult mice (F0 and F1b) showed no significant changes in water consumption, body weight or fertility index and gestation index (number of females with live litters/number of females pregnant) but 'inexplicable' sporadic increases in mortality occurred (details not given). Among the offspring of F0 and F1b animals (F1a, F1b, F2a), no significant changes were seen in mean litter size, mean post-natal body weights (measured on days 7, 14 and 21), or survival (measured on days 4 and 21) and it was reported that there was no evidence of dose-dependent gross pathology or congenital external, visceral or skeletal malformations although no details or data were given. According to the results of the two-generation study in mice, the NOAEL for general and parental toxicity as well as for the F1 and F2 offspring was 50 mg/kg bw/d in each case (Lane et al., 1982).

The reproductive toxicity of 1,2 -dichloroethane was also investigated in a one-generation study in male and female rats after inhalation exposure to 0, 25, 75 or 150 ppm (corresponding to 0, 103, 308 or 617 mg/m³) for 60 exposures (5/wk, 6 h/d) during the premating period and another 116 exposures (7/wk; 6 h/d) for the remainder, but sparing the pregnancy and lactation period for the F0-females. Neither the parental nor the F1 animals revealed any treatment-related changes in clinical and pathological parameters or reproductive performance (Murray et al., 1980 ; Rao et al., 1980). NOAELs from this study were 150 ppm for both parental animals and F1-offsprings and also for signs of general toxicity.

All three studies failed to exhibit clear toxic signs at the doses applied. Therefore, evaluation as to reproduction performances was only possible under this restriction.

The reproductive toxicity of 1,2-dichloroethane was investigated in a one-generation study in male and female Sprague-Dawley rats after inhalation exposure to 0, 25, 75 or 150 ppm (corresponding to 0, 103, 308 or 617 mg/m³), respectively. The premating period was 60 days for both sexes and the mating regimen was one male each with one female for a period of four days to produce the F1a-generation. The F1a-generation was necropsied between postnatal day 21 and 25. Seven days after the last F1a litter was sacrificed parental animals were remated and the produced F1b-litter was necropsied between postnatal days 21 and 25 as well. Maternal exposure was discontinued only from gestation day 21 until lactation day four. Adult animals did not reveal any clinical signs of intoxication and no treatment-related changes in food consumption or body weights were reported. Relative organ weights of liver, kidneys, testes, uterus and ovaries of all dose groups were comparable to controls, too. In the offspring (both F1 generations) no changes in the fertility indices, in the number of pups/litter, gestation survival, pup survival indices on days, 1, 7, 14 and 21, sex ratio at day 21, neonatal body weight and growth was observable. No substance related macroscopical and histopathological changes of liver and kidneys and external, visceral and skeletal malformations or retardations/variations were evident in both F1 -generations (Murray et al., 1980 ; Rao et al., 1980). The NOAEL derived from this study was 150 ppm for both parental animals and F1 -offsprings and signs of general toxicity.

Short description of key information:
In the key study conducted by Lane et al. (1982), there appeared to be no dose-dependent effects on fertility, gestation, viability, or lactation indices. Pup survival and body weight gain were not adversely affected. 1,2 -dichloroethane failed to produce significant dominant lethal mutations or teratogenic effects in either of the two generations tested.

Effects on developmental toxicity

Description of key information

In four oral or inhalation studies in rats and rabbits, intrauterine development of embryos and fetuses was not significantly affected up to maternally toxic doses.

Effect on developmental toxicity: via oral route

Dose descriptor:

NOAEL

158 mg/kg bw/day

Effect on developmental toxicity: via inhalation route

Dose descriptor:

NOAEC

1 200 mg/m³

Additional information

Developmental toxicity/teratogenicity studies were performed in rats and rabbits by the inhalation and oral route of exposure.

In two well conducted studies using pregnant SD rats either exposed to 150, 200, 250 or 300 ppm (6h/d) or to 118, 158, 198 or 238 mg/kg bw/d (corn oil, gavage) from day 6 through 20 p.c., no treatment-related differences were seen in mean litter size, foetuses per litter, in numbers of implantations, incidence of resorptions, foetal body weight and the incidence of malformations length, sex ratio as compared to controls at maternally non-toxic doses/concentrations of either exposure regimen, except some embryolethal effects (increase in non-viable implants and resorption sites per litter), significant in the oral dose-groups of 200 mg/kg bw/d and higher (p< 0.05). Distinct maternal toxicity was indicated by intermittent delayed body weight gains and expressed by a decrease in the absolute body weight gain of dams and by three and two stillborn/not viable litters delivered at 240 mg/kg bw/d and 300 ppm, respectively (Payan et al., 1995).

Accordingly, the NOAELs(inhalation/oral) were at 250 ppm and 158 mg/kg bw/d for maternal general toxicity, and 300 ppm for embryo-/fetotoxicity/teratogenicity, and at 238 mg/kg bw/d for fetotoxicity/teratogenicity, but at 158 mg/kg bw/d for embryotoxicity, respectively.

In the limited inhalation rat study by Rao et al. (1980) using only two concentrations of 100 and 300 ppm, the NOAEL was 100 ppm for maternal and developmental toxicity, while the high exposure level showed overt toxicity (10/16 dams dead). An intermediate, less maternally toxic levels appeared to be missing in order to identify the appropriate NOAEL. In the respective inhalation study conducted in rabbits (Rao et al., 1980), the NOAEL for developmental effects was at 300 ppm with unclear maternal toxicity, as several dams died at either exposure level without signs of intoxication.

In principal, the observations of the latter were in line with those of the more comprehensive studies by Payan et al. (1995).

Justification for classification or non-classification

Overall, three generation studies by the oral or inhalation route in rats and mice gave no evidence of impairment of the parental reproductive performance and pre- and postnatal viability and development of the progeny. In four oral or inhalation studies in rats and rabbits, intrauterine development of embryos and fetuses was not significantly affected up to maternally toxic doses. Based on Directive 67/548/EEC and on Regulation 1272/2008 (CLP, GHS), 1,2-dichloroethane was not classified as reproductive or developmental toxicant.