Oral toxicity study of 2-pentenenitrile in rats with reproductive toxicity screening test

A combined repeated-dose toxicity study with reproduction was conducted with 2-pentenenitrile (2-PN). Rats (10/sex per dose level) were dosed with 2-PN once daily by gavage at dose levels of either 0, 1, 3, or 10 mg kg(-1) day(-1) for 28 days, prior to and during cohabitation, and through day 3 of lactation. General clinical observations were recorded daily; body weights were recorded weekly. A neurobehavioral evaluation consisting of a functional observational battery and motor activity was conducted in all parental rats (10/sex per group). Clinical pathology parameters (hematology, clinical chemistry, coagulation) were measured in parental rats. Pup weights and clinical signs were recorded at birth and on lactation day 4. Parental rats were given a gross pathological examination, organ weights were obtained, and histological examination was conducted for the control and 10 mg kg(-1) day(-1) groups. No effects were seen with regard to mortality, clinical signs, functional observational battery and motor activity, hematology, or organ weights. Females receiving 10 mg/kg and males from all dose groups showed lower body weight gains and feed efficiency. Increased albumin concentrations were seen in both sexes given 10 mg/kg. Females in the 10 mg/kg group showed degeneration of the olfactory mucosa. No effects on the numbers of pups born, number surviving to lactation day 4, pup weight, and no gross anatomical development changes were observed. Under the conditions of this study, the no-observed-effect level (NOEL) for systemic toxicity in rats was 3 mg kg(-1) day(-1), based on degeneration of olfactory mucosa in females at 10 mg kg(-1) day(-1). The NOEL for reproductive and neurobehavioral toxicity in rats and for toxicity to offspring was 10 mg kg(-1) day(-1), the highest dose level tested.

Inhalation toxicity of methylglutaronitrile in rats

Methylglutaronitrile (MGN) is a high-boiling (263 degrees C) solvent/intermediate used in the fiber industry. Twenty male rats per group were exposed nose-only to condensation aerosol/vapor concentrations of approximately either 5, 25, or 200 mg/m3 of MGN for 6 h/day, 5 days/week over a 4-week period. Ten rats/group were sacrificed one day after the final exposure and the remaining rats after a four-week recovery period. No effects were observed in clinical observations during the exposure period, but body-weight depression was observed in the 200 mg/m3 group. The 200 mg/m3 group showed minimal decreases in red blood cell count, hemoglobin, and hematocrit values accompanied by increases in reticulocytes. There were no other effects observed in clinical or pathologic evaluations in the study. A neurobehavioral battery of tests (including grip strength, functional observational battery, and motor activity tests) given at the end of the exposure and recovery periods showed no MGN effects. During the 4-week recovery, body weights in the 200 mg/m3 group returned to normal and the hematologic findings in all groups were normal. Based on the above findings of body weight depression at 200 mg/m3, the no-observed-adverse-effect level (NOAEL) for this study was considered to be 25 mg/m3.