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A 90-day inhalation toxicity study with benomyl in rats
D B Warheit1, D P Kelly, M C Carakostas
1E. I. du Pont de Nemours and Company, Inc., Newark, Delaware 19714.
Summary
This study found that benomyl fungicide exposure caused olfactory epithelium degeneration in rats. The no-observable-effect levels (NOEL) were 10 mg/m³ for males and 50 mg/m³ for females.
Area of Science:
- Toxicology
- Environmental Health
- Occupational Safety
Background:
- Benomyl is a widely used fungicide with potential for inhalation exposure in agricultural settings.
- Assessing the toxicological profile of benomyl is crucial for understanding risks to field workers.
Purpose of the Study:
- To evaluate the toxicity of benomyl following repeated inhalation exposure in rats.
- To determine the no-observable-effect level (NOEL) for benomyl in male and female rats.
Main Methods:
- Rats were exposed nose-only to varying concentrations of benomyl (0, 10, 50, 200 mg/m³) for 90 days.
- Clinical evaluations, blood and urine analyses, and pathological examinations were conducted at midpoint and end of study.
- Olfactory epithelium integrity and body weight changes were key endpoints.
Main Results:
- Benomyl exposure caused dose-dependent olfactory epithelial degeneration in both male and female rats.
- Degeneration was observed at 50 mg/m³ and 200 mg/m³ concentrations.
- Male rats at 200 mg/m³ showed reduced body weight and food consumption.
Conclusions:
- The no-observable-effect level (NOEL) for male rats was determined to be 10 mg/m³.
- The NOEL for female rats was determined to be 50 mg/m³.
- Olfactory epithelium damage is a primary toxic effect of benomyl inhalation.