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Published on: February 22, 2016
Determination of acute toxic effects in mice following exposure to methyl bromide
Abstract:
An inhalation system was designed and constructed for acute nose exposure of mice to methyl bromide. Animals were exposed for 1 h to concentrations ranging from 0.87 to 5.93 mg/l. Mice exposed to concentrations up to 1.72 mg/l did not exhibit any indication of developing a toxic response. Animals exposed to concentrations to 2.20 and 2.70 mg/l exhibited significantly decreased lung and liver weights when compared to controls. Animals exposed to concentrations above 3.50 mg/l exhibited kidney lesions. At concentrations of 3.82 mg/l and above, animals exhibited abnormal clinical signs, weight loss, and mortality. In addition, at 4.70 mg/l, a liver lesion was observed. At concentrations above 5.77 mg/l, pathological changes were observed in the color and a decreased motor coordination was evident. Methyl bromide exposures of up to 3.82 mg/l did not affect the ability of mice to recall a single-task passive-avoidance test. The 1-h LC50 of methyl bromide in mice via inhalation was determined to be 4.68 mg/l (approximately 1200 ppm). The dose-response curve was quite steep and the LC10 to LC90 range of mortality was contained within a doubling of concentration.
Insights
Acute inhalation of methyl bromide in mice causes toxicity, including organ damage and mortality, at concentrations above 2.20 mg/l. The 1-hour lethal concentration 50 (LC50) was determined to be 4.68 mg/l.
Area of Science:
- Toxicology
- Environmental Health
- Occupational Safety
Background:
- Methyl bromide is a fumigant with known toxicity.
- Understanding acute inhalation toxicity is crucial for risk assessment.
Purpose of the Study:
- To determine the acute inhalation toxicity of methyl bromide in mice.
- To establish dose-response relationships and identify target organs.
Main Methods:
- A specialized inhalation system was used for nose-only exposure of mice.
- Animals were exposed to varying concentrations of methyl bromide for 1 hour.
- Clinical signs, organ weights, histopathology, and a passive-avoidance test were assessed.
Main Results:
- No toxic effects were observed up to 1.72 mg/l.
- Decreased lung and liver weights occurred at 2.20-2.70 mg/l.
- Kidney lesions, clinical signs, weight loss, and mortality were seen above 3.50 mg/l.
- The 1-hour LC50 was 4.68 mg/l (approx. 1200 ppm).
- Cognitive function was unaffected up to 3.82 mg/l.
Conclusions:
- Methyl bromide exhibits significant acute inhalation toxicity in mice.
- Target organs include lungs, liver, and kidneys, with neurological effects at higher concentrations.
- The steep dose-response curve highlights the rapid increase in toxicity with concentration.
