1. Epidemiology and Toxicology of Disinfection By-Products
NCI (1976): chloroform – animal carcinogen
SUMMARY OF HEALTH RISKS – EPA (1995)
What are the health effects in communities receiving disinfected drinking water?
What is the toxicity of individual by-products and mixtures of by-products?
How do we characterize the risks?
How do risks posed by DBPs compare with risks posed by microorganisms?

2. Carcinogenicity
Weight of evidence for carcinogenicity: from communities (humans) and animal studies
Epidemiological studies
A slightly increased risk of bladder, colon, and rectal cancer following long-term exposure to to chlorinated water (ecological studies & case-control studies)?
Exposure definition? – chlorinated water, chloroform, THMs, etc.
Prospective cohort study

3. Carcinogenicity Animal studies Uncertainties in cancer studies
Lifetime oral exposure – liver, kidney, and intestinal cancers (four THMs, DCAA and TCAA, chloral hydrate, bromate, and MX)
Uncertainties in cancer studies
Extrapolation of the results observed in animal studies to predict human risk

4. Reproductive and Developmental Toxicity
Epidemiological studies
Infant growth retardation and low birth weight (CF > 10 μg/L)
Stillbirth, congenital deformaties, and infant deaths
Low birth weight, central nervous system defects, neural tube defects, and cardiac defects
Miscarriage (spontaneous abortion), preterm delivery, and low birth weight ……

5. Reproductive and Developmental Toxicity
Animal studies
Impairments to sperm mobility, morphology, and maturation – BDCM, DCAA, TCAA, MBAA, DBAA, CH, bromate
Decreased fertility by DBAA at doses of 10 mg/kg
Uncertainties for reproductive and developmental effects
Limited database
Exposure assessment
Control for important risk factors – smoking and exposure from other drinking water contaminants