1,2 Dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB) in well water in the Fresno/Clovis metropolitan area, California.

Ground-water contamination with the pesticides 1,2 dibromo-3-chloropropane (DBCP) and ethylene dibromide (EDB) affects Fresno/Clovis city in California. The spatial and temporal distribution of DBCP and EDB in public wells in Fresno/Clovis was examined, using mapping and time-series analyses of chemical test results, during the time periods 1979-1980 and 1992-1993. Health risks were estimated from mean concentrations, lifetime cancer risks were estimated, and monitoring and control programs were reviewed. Mean DBCP concentrations in selected wells declined from 0.56 ppb in 1979-1980 to 0.18 ppb in 1992-1993. Closure of wells and wellhead filtration caused levels to be reduced further (i.e., to 0.06 ppb). Mean EDB concentrations declined from 0.25 ppb to 0.15 ppb during the same time periods. The estimated lifetime cancer risk for DBCP was 1 excess death per 125 000 population in 1992-1993, but this risk varied within the city. The risk for EDB was 1 excess death per 2.2 million. Recommendations were made for the modeling of pesticide movement in ground water and for epidemiological studies.