title: Evaluating Evidence for Association of Human Bladder Cancer with Drinking-Water Chlorination Disinfection By-Products.
abstract: Exposure to chlorination disinfection by-products (CxDBPs) is prevalent in populations using chlorination-based methods to disinfect public water supplies. Multifaceted research has been directed for decades to identify, characterize, and understand the toxicology of these compounds, control and minimize their formation, and conduct epidemiologic studies related to exposure. Urinary bladder cancer has been the health risk most consistently associated with CxDBPs in epidemiologic studies. An international workshop was held to (1) discuss the qualitative strengths and limitations that inform the association between bladder cancer and CxDBPs in the context of possible causation, (2) identify knowledge gaps for this topic in relation to chlorine/chloramine-based disinfection practice(s) in the United States, and (3) assess the evidence for informing risk management. Epidemiological evidence linking exposures to CxDBPs in drinking water to human bladder cancer risk provides insight into causality. However, because of imprecise, inaccurate, or incomplete estimation of CxDBPs levels in epidemiologic studies, translation from hazard identification directly to risk management and regulatory policy for CxDBPs can be challenging. Quantitative risk estimates derived from toxicological risk assessment for CxDBPs currently cannot be reconciled with those from epidemiologic studies, notwithstanding the complexities involved, making regulatory interpretation difficult. Evidence presented here has both strengths and limitations that require additional studies to resolve and improve the understanding of exposure response relationships. Replication of epidemiologic findings in independent populations with further elaboration of exposure assessment is needed to strengthen the knowledge base needed to better inform effective regulatory approaches.
authors: a Environmental and Analytical Toxicology, Faculty of Medicine & Dentistry , University of Alberta , Edmonton , Alberta , Canada.
authors: Steve E
authors: SE
authors: Hrudey
authors: b Centers for Disease Control and Prevention , Atlanta , Georgia , USA.
authors: Lorraine C
authors: LC
authors: Backer
authors: c SA Water, 250 Victoria Square , Adelaide , South Australia , Australia.
authors: Andrew R
authors: AR
authors: Humpage
authors: d Metropolitan Water District of Southern California , Los Angeles , California , USA.
authors: Stuart W
authors: SW
authors: Krasner
authors: e Tufts University , Medford , Massachusetts , USA.
authors: Dominique S
authors: DS
authors: Michaud
authors: f Epidemiologist , Bethesda , Maryland , USA.
authors: Lee E
authors: LE
authors: Moore
authors: g University of North Carolina , Chapel Hill , North Carolina , USA.
authors: Philip C
authors: PC
authors: Singer
authors: h Hazen and Sawyer , Raleigh , North Carolina , USA.
authors: Benjamin D
authors: BD
authors: Stanford
mesh_terms: D002700:Chloramines / Q000633:toxicity; D002713:Chlorine / Q000633:toxicity; D004202:Disinfectants / Q000633:toxicity*; D004203:Disinfection; D060766:Drinking Water / Q000032:analysis; D004781:Environmental Exposure; D054879:Halogenation; D006801:Humans; D018570:Risk Assessment; D014481:United States; D001749:Urinary Bladder Neoplasms / Q000139:chemically induced / Q000453:epidemiology*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D018508:Water Purification
chemical_list: D002700:Chloramines; D004202:Disinfectants; D060766:Drinking Water; D014874:Water Pollutants, Chemical; D002713:Chlorine; C030816:chloramine