Risk assessment for butadiene: Introductory and summary comments

Butadiene and its 2-methyl analog, isoprene, are important chemicals, extensively studied in animals and in worker cohorts. This symposium, building on previous conferences and substantial additional metabolic and epidemiologic data, brought together leading scientists from industry and academia and knowledgeable regulators to address the complex task of assessing likelihood and magnitude of risk to humans and appropriately protective standards for occupational and general environmental exposures. These agents and these discussions are an excellent case study for general challenges in risk assessment and risk management.