1,3-Butadiene: linking metabolism, dosimetry, and mutation induction

Area of Science:

• Toxicology and Environmental Health
• Chemical Carcinogenesis and Mutagenesis
• Interspecies Comparative Metabolism

Background:

• Growing concern exists regarding adverse health effects from human exposure to chemical mixtures.
• 1,3-Butadiene (BD) is a known multisite carcinogen in rodents, with mice exhibiting higher sensitivity than rats.
• Understanding BD's metabolic activation and detoxification is crucial for assessing risks associated with BD and chemical mixtures.

Purpose of the Study:

• To investigate interspecies differences in the metabolic activation and detoxification of 1,3-butadiene (BD).
• To provide a basis for extrapolating single chemical data to chemical mixture behavior.
• To enhance the understanding and assessment of human health risks from BD exposure.

Main Methods:

• Exposure of transgenic mice to 625 ppm 1,3-butadiene (BD) for specific durations.
• Assessment of mutagenicity in target organs, specifically the lung.
• In vitro studies to compare BD activation and epoxide inactivation rates across mice, rats, and humans.

Main Results:

• Significant mutagenicity was observed in the lungs of BD-exposed transgenic mice.
• Substantial interspecies differences were identified in BD metabolism.
• The activation/detoxication ratio for BD metabolism was approximately 10-fold higher in mice compared to rats and humans.

Conclusions:

• Interspecies differences in 1,3-butadiene (BD) metabolism significantly influence carcinogenic response.
• Mice exhibit a higher capacity for BD activation relative to detoxification compared to rats and humans.
• These findings are critical for improving risk assessments of BD and chemical mixtures containing BD.