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Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via inhalation route
Dose descriptor:
NOAEC
360 mg/m³
Additional information

Effects on fertility

No effects on male fertility (reproductive performance, organs or function) were observed in a reproduction screening study in which rats (ChR-CD strain) were exposed to chloroprene via inhalation at 25 ppm for 4 hours/day, for 22 consecutive days.

In another study, the effects of chloroprene exposure on sperm concentration and abnormalities were assessed in rats following inhalation exposures at 0, 10, 33 or 100 ppm for 6 hours/day, 5 days/week for 26 weeks. Chloroprene exposure had no apparent effect on parameters of male fertility: the mean sperm concentration and mean numbers of total and differentiated abnormal sperm cells showed no evidence of any treatment-related effects. Although a high incidence of abnormally shaped sperm heads was observed in rats treated at 10 ppm, this was attributed to a single rat with more than 568 abnormalities /1000 cells examined and was regarded as an anomalous result.

No effects on fertility were observed in a one-generation study in Wistar rats following inhalation exposures to chloroprene up to 100 ppm. The NOAEC for reproductive toxicity was regarded as > 100 ppm (362 mg/m3).

In an NTP study (NTP, 1998)groups of 10 male and 10 female F344/N rats were exposed to chloroprene by inhalation at 0, 5, 32, 80, or 200 ppm by inhalation, 6 hours per day, 5 days per week, for 13 weeks. Sperm parameters and vaginal cytology were investigated at the end of the study. One male exposed to 200 ppm died during the study. The final mean body weights and body weight gains of all exposed groups of males and females were similar to those of the chamber control groups.

Exposure to chloroprene had no effect on estrous cyclicity in female rats; the NOAEC for effects on female fertility was 200 ppm (724 mg/m3). The only significant finding in male rats was reduced sperm motility in the 200 ppm compared to chamber controls, the NOAEC for effects on male fertility was considered to be 32 ppm 115 mg/m3).

In a comparable NTP study in B6C3F1 mice, groups of 10 animals per sex were exposed to chloroprene at 0, 12, 32 or 80 ppm by inhalation, 6 hours per day, 5 days per week, for 13 weeks. Sperm parameters and vaginal cytology were investigated at the end of the study. There were no deaths during the study, and no clinical findings were reported. The final mean body weights and body weight gains of 80 ppm males were significantly less than those of the chamber control group. Sperm morphology and vaginal cytology parameters of exposed male and female mice were similar to those of the chamber controls, therefore the NOAEC is considered to be 80 ppm (289.6 mg/m3).


Short description of key information:
In a 13-wk NTP inhalation study in F344 rats, chloroprene caused a slight reduction in sperm motility in 200 ppm males, otherwise no reproductive organ function or effects were produced by chloroprene in male or female rats and mice. The significance of the slight reduction in sperm motility in male rats is diminished as historical control data for sperm motility were not presented and no adverse effects on fertility have been observed in dominant lethal or in a one-generation study in Wistar rats exposed to 100 ppm or in sperm abnormality studies after 26 wks of inhalation exposure up to 100 ppm. The NOAEC for reproductive toxicity was 100 ppm (360 mg/m3) based on absence of reproductive effects in a one generation study at 100 ppm and reduced sperm motility in rats at 200 ppm.”

Effects on developmental toxicity

Description of key information
The developmental toxicity of chloroprene following inhalation exposures have been investigated in rats and rabbits and reproductive toxicity has been investigated in a one generation study. Chloroprene was not found to be teratogenic or embryotoxic to rats following maternal inhalation exposures. A NOEC of 10 ppm (36.2 mg/m3) was proposed for maternal toxicity based on reduced food consumpion and lower bodyweight gains at higher exposure levels. The NOAEC for developmental effects following inhalation exppsures was > 25 ppm (90.5 mg/m3)
Effect on developmental toxicity: via inhalation route
Dose descriptor:
NOAEC
90.5 mg/m³
Additional information

Developmental toxicity

The developmental toxicity of chloroprene following inhalation and oral exposures has been investigated in rats and rabbits. Although these studies were conducted prior to the introduction of GLP and formal testing guidelines, they have been conducted in general accordance with current test guidelines and can be regarded as reliable.

In studies of the embryotoxic and teratogenic effects of inhalation exposures to chloroprene, pregnant female rats (ChR-CD strain) were exposed to vapours at 0, 10 or 25 ppm from gestation day (GD) 2 to 20 or from GD 1 to 12 respectively for 4 hours/day. No adverse effects were observed in dams at any of the dose levels. No treatment-related effects were observed on bodyweight, gravid uterus weight, pre- and post-implantation losses, fertilised ova losses or the number of live foetuses per litter. Embryo development based on weight and size was unaffected by maternal inhalation exposures to chloroprene up to 25 ppm: no major external, skeletal or soft tissue malformations. Chloroprene was not found to be teratogenic or embryotoxic to CD rats under the conditions of the two studies. The NOEC for dervelopmental effects was > 25 ppm (90.5 mg/m3)

 

In another embryotoxic/teratogenic study, pregnant Wistar rats were exposed to chloroprene vapours at 0, 10, 25, 75 or 175 ppm from either GD 6 to 16 or GD 4 to 15. There were no mortalities among the dams. In rats treated at 175 ppm, clinical signs included salivation and alopecia. Maternal bodyweights were reduced at exposure at and greater than 25 ppm. No gross treatment-related changes were observed in dams in macroscopic examinations. Reduced numbers of corpora lutea numbers and implantation sites in the high dose groups were within background ranges and not considered to be treatment-related. Pre-implantation losses in the high dose group were less than in the controls, suggesting that chloroprene does not affect early stages of development. Although an increased incidence of embryonic resorptions resulted in a significant increase in post-implantation loss in dams treated at 10, 75 and 175 ppm, this response had not been apparent at these dose levels in a preliminary study, did not observe a dose-response relationship and was not considered to be treatment-related. The number of live foetuses, the empty uterus weight and the foetal weights were all reduced following exposures at 75 or 175 ppm. No soft tissue foetal abnormalities were observed at any dose level and some skeletal anomalies were observed which were not regarded as treatment-related. Although significant differences in skeletal ossification were observed in treated rats, no clear dose-response relationship was observed and parameters were within historical control ranges.

Inhalation exposures to chloroprene vapours up to 175 ppm were not found to induce major embryogenic or teratogenic effects in rats. A NOEC of 10 ppm was proposed for maternal toxicity based on reduced food consumption and lower body weight gains at exposures at 25 ppm or above. Some indication of embryotoxicity (reduced fetal weights) was observed at 75 and 175 ppm.

Inhalation exposures to chloroprene up to 100 ppm were not found to induce adverse toxicological effects or affect the reproductive performance, fertility or offspring in a two-generation reproductive toxicity study in Wistar rats. In the study F0 and F1 generations were exposed via inhalation to chloroprene vapours at 0, 10, 33 or 100 ppm for 6 hours/day for 5 weeks for 13 weeks and for 10 weeks respectively. Reduced weight gains were observed in rats treated at 33 or 100 ppm, with more pronounced effects occurring in the F1 group. The slight decrease in relative lung weight for F1 females treated at 100 ppm was not associated with any pathological change and not considered as toxicologically significant. No significant effects were observed on male or female fertility, the number of young born per litter or the general clinical condition or appearance, male/female ratio or mortality of the treated rats. The NOAEC for reproductive toxicity was regarded as > 100 ppm.

In a study of the potential for chloroprene to cause developmental toxicity in female New Zealand white rabbits, artificially inseminated animals were exposed to 0, 10, 40 or 175 ppm chloroprene vapour 6 hours/day, 7 days/week on gestation days 6 to 28 (Mast et al, 1994).

No overt signs of maternal toxicity and no effects on maternal body weight change were observed. Exposure of pregnant rabbits to chloroprene vapours on gestational days 6 -28 had no effect on the number of implantations, the mean percent of live pups per litter, or on the incidence of resorptions per litter. Foetal body, kidney, and liver weights (as means of litter means) were not affected by gestational exposure, nor was the foetal sex ratio affected. The incidence of foetal malformations was not increased by exposure. There were no significant alterations in the incidence of total foetal variations or reduced ossifications among exposed groups.

Results indicated that gestational exposure of New Zealand white rabbits to 10, 40, or 175 ppm chloroprene did not result in observable toxicity to either the dam or the offspring. The highest exposure group, 175 ppm (663.5 mg/m3), was regarded as no observable adverse effect level (NOAEC) for rabbits with respect to both maternal and developmental toxicity.

Justification for classification or non-classification

Chloroprene is not classified for reproductive or developmental toxicity according to EU classification legislation.