13-week inhalation toxicity study of dimethylformamide (DMF) in cynomolgus monkeys.

This study was conducted to assess the subchronic inhalation toxicity of dimethylformamide (DMF) in the cynomolgus monkey. Particular attention was paid to the liver since DMF has been shown to produce liver damage in rodents, dogs, and humans. Groups of three cynomolgus monkeys/sex/group received whole-body exposures for 6 hr/day, 5 days/week for 13 weeks to 0, 30, 100, or 500 ppm DMF. Evaluations for toxicity included body and organ weights, clinical observations, hematology, serum chemistry, urinalysis, and gross and microscopic examinations. Clinical laboratory evaluations were conducted twice prior to the start of the study at exposure weeks 2, 4, 8, and 12 and at necropsy. Semen, collected from male monkeys three times prior to the start of the study and weekly during the course of the study, was analyzed for sample volume, sperm count, motility, and morphology. In addition, daily vaginal swabs were obtained from all females prior to exposure to determine mean menses cycle length. Although there was a slight trend toward increased cycle length, this trend could not be definitely attributed to compound exposure. Based on extensive monitoring of the monkeys' clinical condition, semen quantity and quality, and clinical and pathological evaluations, no exposure-related adverse health effects were detected following exposure to concentrations of DMF ranging from 30 to 500 ppm for 13 weeks.