DESIGN OF AN EPIDEMIOLOGIC-STUDY OF DRINKING-WATER ARSENIC EXPOSURE AND SKIN AND BLADDER-CANCER RISK IN A US POPULATION

Ingestion of arsenic-contaminated drinking water is associated with an increased risk of several cancers, including skin and bladder maligna ncies; but it is not yet clear whether such adverse effects are presen t at levels to which the U.S. population is exposed. In New Hampshire, detectable levels of arsenic have been reported in drinking water sup plies throughout the stale. Therefore, we have begun a population-base d epidemiologic case-control study in which residents of New Hampshire diagnosed with primary squamous cell (n=900) and basal cell (n=1200) skin cancers are being selected from a special statewide skin cancer i ncidence survey; patients diagnosed with primary bladder cancers (n=45 0) are being identified through the New Hampshire Stale Cancer Registr y. Exposure histories of these patients will be compared to a control group of individuals randomly selected from population lists (n=1200). Along with a detailed personal interview, arsenic and other trace ele ments are being measured in toenail clipping samples using instrumenta l neutron activation analysis. Household water samples are being teste d on selected participants using a hydride generation technique with h igh-resolution inductively coupled plasma mass spectrometry. In the fi rst 793 households tested, arsenic concentrations ranged from undetect able (0.01 mu g/l) to 180 mu g/l. Over 10% of the private wells contai ned levels above 10 mu g/l and 2.5% were above 50 mu g/l. Based on our projected sample size, we expect at least 80% power to detect a 2-fol d risk of basal cell or squamous cell skin cancer or bladder cancer am ong individuals with the highest 5% toenail concentrations of arsenic.