Hydrocarbons, C7-8

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Additional information

There are no data available on the effects on fertility of hydrocarbons, C7-C8, cyclics. Thus, read-across from a structurally related substance (commercial hexane) was performed, for which reliable information exists.

In a reliable two generation reproduction study performed according to OECD 416, CD (Sprague Dawley) rats were whole body exposed to vapour of commercial hexane (Neeper-Bradley, 1991). Exposure to commercial hexane (approx. 52% n-hexane) was at 0, 900, 3000 or 9000 ppm for 6 h/day, 5 days/week during a 70 day (10 weeks) pre-mating period and the 21 day (3 weeks) mating period. Females were further exposed during gestation (GD 1-19) and lactation (LD 5 to weaning). The F1 generation was treated similarly but the pre-mating exposure was 8 weeks (56 days). Animal observations included mortality, clinical signs, food consumption, and body weight. Offspring were examined for body weight, survival, and viability. Both parental animals and offspring were sacrificed and examined for gross abnormalities. Histopathological examinations were conducted on adult animals.

Hexane exposure did not induce adverse effects on fertility. Reproductive indices were similar in exposed and control groups. No macroscopic or microscopic alterations in male and female reproductive organs were observed. The only significant effect was reduced body weight in the F1 and F2 generations in both sexes in the 9000 ppm exposure group both in adults and offspring.

The NOAEC for both male and female rats (adults and offspring) was 3000 ppm (corresponding to 10560 mg/m3). The LOAEC for these groups was 9000 ppm based on reduced body weight. There were no adverse effects on reproduction; therefore the NOAEC for reproduction is 9000 ppm which corresponds to 31680 mg/m3.

Short description of key information:
NOAEC (rat) = 31680 mg/m3

Effects on developmental toxicity

Description of key information

NOAEC (mouse) = 10560 mg/m3
NOAEC (rat) = 31680 mg/m3

Additional information

There are no data available on the developmental toxicity of hydrocarbons, C7-C8, cyclics. Read-across based on a category approach was conducted from a structurally related substance, for which reliable information exists.

A Segment II teratology study on hydrocarbons, C7-C9, isoalkanes, showed no evidence of embryonic or teratogenic effects in rats (ExxonMobil Chemical,1979). In this study, pregnant rats were exposed to 0, 400, or 1200 ppm for 6 h/day during gestational days 6 to 15. There was no mortality and no treatment-related effects to the dams. No treatment-related effects were observed in the number of live foetuses, foetal size, sex distribution, and external soft-tissue or skeletal examinations. Under the conditions of the study, there was no evidence of embryotoxicity or teratogenicity. The NOAEC for developmental toxicity was 1200 ppm, the highest dose tested.

Available data on the developmental toxicity of a further structurally related substance (commercial hexane) was taken into account for assessment. Thus, read-across from a structural analogue was conducted, for which reliable information exists.

The potential developmental toxicity of commercial hexane was examined in two reliable studies performed according to OECD 414 with mice and rats, respectively (Neeper-Bradly, 1989). Groups of pregnant female animals (30 CD-1 mice, 25 Sprague-Dawley rats) were whole body exposed to vapour of commercial hexane (approx. 52% n-hexane) at 0, 900, 3000, or 9000 ppm for 6 h/day during gestational days (GD) 6-15. Following exposure, animals were sacrificed on GD 18 (mice) or 21 (rats). During the study, animals were examined for clinical signs, mortality, food and water consumption, and body weight gain. After sacrifice, the internal organs were examined, and the uterus was examined for viable foetuses, number of resorptions, and number of corpora lutea. Foetuses were examined for malformations.

Necropsy of mice revealed colour changes in the lungs of females in the 3000 and 9000 ppm groups. Foetuses from dams in the 9000 ppm group had a statistically significant increase in the incidence of some skeletal abnormalities. Rats showed colour changes in the lungs of females in the 9000 ppm groups along with reduced body weight gain, and reduced food consumption. No treatment-related abnormalities were seen in the foetuses.

The maternal NOAEC in mice was 900 ppm (3168 mg/m3), and the LOAEC 3000 ppm (10560 mg/m3) based on lung colour changes. The developmental NOAEC in mice was 3000 ppm (10560 mg/m3) and the LOAEC 9000 ppm (31680 mg/m3) based on skeletal abnormalities.

In rats, the maternal NOAEC was 3000 ppm (10560 mg/m3), and the LOAEC 9000 ppm (31680 mg/m3) based on lung colour changes, reduced body weight gain, and reduced food consumption. The developmental NOAEC in rats was 9000 ppm, corresponding to 31680 mg/m3.

Justification for classification or non-classification

Based on read-across from from a structurally related substance, no reproductive toxicity effects are expected after exposure to hydrocarbons, C7-C8, cyclics. No need for classification according to the DSD and CLP criteria for classification and labelling.