I have 36 years of experience, and specialize in the field of health risk assessment with specific knowledge in the areas of chemical risk assessment, asbestos and health assessment of metals. I have published on such topics as health effects of arsenic, health effects of chromium and health effects of mercury. I have testified 26 times on topics such as asbestos, disinfection byproducts and organophosphates. I had a 29 year career at the United States Environmental Protection Agency. I have been a consultant to the World Health Organization for 20 years.