ASSESSMENT OF TOXIC METAL EXPOSURE FOLLOWING THE CAMELFORD WATER-POLLUTION INCIDENT - EVIDENCE OF ACUTE MOBILIZATION OF LEAD INTO DRINKING-WATER

Following the incident of acidic pollution of water by aluminium sulfa te centred around Camelford in July 1988, we have carried out a retros pective analysis of the mobilization of toxic metals to residents of t he area. An advanced nuclear technique was used to measure trace level s of elements within hair, thus, avoiding surface contamination. In co ntrast to controls, lead, but no other toxic metals, was consistently found within sections of hair that dated to mid-1988 from four residen ts; they must, therefore, have consumed this metal around the time of the incident. The source of this lead was probably local water pipe re sidue, and this was found on analysis to have a matrix specific to suc h soft-water areas that, prior to the incident, had slowly accumulated certain toxic metals such as cadmium and uranium and particularly lea d. Lead is mobilized from such residues by acidic water and could, the refore, have heavily contaminated mains water after the incident. Howe ver, analyses of residents' plasma and whole blood, and of urine follo wing a lead-chelation test, showed no evidence of either long-term inc reased body burdens of toxic metals or depletion of essential elements . In addition, we found no evidence of continued poor water quality in the area. In conclusion, during a short period following the pollutio n, some residents who consumed mains water would have been acutely exp osed to lead and other toxic metals. Prediction of the scale of metal exposure to individuals was not possible owing to heterogeneity of the water distribution network, but long-term effects to residents from l ead are not anticipated. The accumulation of uranium in such residues and its potential for acute mobilization require further study.