A 90-day inhalation toxicity study with benomyl in rats.

Abstract

Benomyl [methyl 1-(butylcarbamoyl)-2-benzimidazolecarbamate, CAS Registry No. 17804-35-2] is a fungicide and the possibility for inhalation exposure exists for field workers. To assess the toxicity of benomyl, groups of 20 male and 20 female CD rats were exposed nose-only 6 hr a day, 5 days a week, to concentrations of 0, 10, 50 or 200 mg/m3 of a benomyl atmosphere. At the midpoint (approximately 45 days on test) and at the end of the exposure period, blood and urine samples for clinical evaluation were collected from 10 rats/group/sex, and these animals were sacrificed for pathological examination. Similar evaluations were performed on all remaining rats at the end of the 90-day test period. After approximately 45 days on test, compound-related degeneration of the olfactory epithelium was observed in all males and in 8 of 10 female rats exposed to 200 mg/m3 benomyl. Two male rats exposed to 50 mg/m3 had similar, although less severe, areas of olfactory epithelial degeneration. After approximately 90 days of exposure, the remaining 10 rats/group/sex were sacrificed and examined. Of these rats, all of the males and females exposed to 200 mg/m3 had olfactory degeneration, along with 3 males exposed to 50 mg/m3 of benomyl. No other observed lesions were interpreted to have been caused by the benomyl exposure. In addition, male rats exposed to 200 mg/m3 benomyl had depressed mean body weights compared to controls and this finding correlated with a reduction in food consumption. Based on pathological observations, 10 mg/m3 represents the no-observable-effect level (NOEL) for the male rats, and 50 mg/m3 is the NOEL for the female rats.

• Authors: D B Warheit, D P Kelly, M C Carakostas, A W Singer
• Journal: Fundamental and applied toxicology : official journal of the Society of Toxicology (Fundam Appl Toxicol) Vol. 12 Issue 2 Pg. 333-45 (Feb 1989) ISSN: 0272-0590 [Print] United States
• PMID: 2714532 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Carbamates
• Benomyl

Topics

• Administration, Inhalation
• Animals
• Atmosphere Exposure Chambers
• Benomyl (toxicity)
• Body Weight (drug effects)
• Carbamates (toxicity)
• Eating (drug effects)
• Eye (anatomy & histology)
• Female
• Lethal Dose 50
• Male
• Organ Size (drug effects)
• Rats
• Rats, Inbred Strains
• Respiratory System (anatomy & histology)
• Sex Factors