Several epidemiologic studies indicate that there may be a risk of cancer from use of chlorinated tap water. However, to-date, the health effects observed in single-chemical animal toxicity studies (primarily liver cancer) have not been able to explain the effects observed in the human epidemiologic studies (primarily bladder cancer). More recent epidemiologic studies have focused on reproductive and developmental effects. And, although there have been associations observed between chlorinated tap water and these effects, it is not known which chemicals / disinfection by-products (DBPs) in the water may be responsible. Also, because previous toxicological research has focused on single chemical testing, it is not known how the complex mixture of DBPs (typically more than 300 chemicals) affects the overall toxicity and human health risk assessments (are the effects additive or non-additive?). Conference presentations will cover the latest DBP research focused on occurrence and formation, treatment, exposure, toxicity, and epidemiology, and stimulate dialog between chemists, toxicologists, epidemiologists, and engineers in this area.