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 sulfate centred around Camelford in July 1988, we have carried out a retrospective analysis of the mobilization of toxic metals to residents of the area. An advanced nuclear technique was used to measure trace levels of elements within hair, thus, avoiding surface contamination. In contrast to controls, lead, but no other toxic metals, was consistently found within sections of hair that dated to mid-1988 from four residents; they must, therefore, have consumed this metal around the time of the incident. The source of this lead was probably local water pipe residue, and this was found on analysis to have a matrix specific to such soft-water areas that, prior to the incident, had slowly accumulated certain toxic metals such as cadmium and uranium and particularly lead. Lead is mobilized from such residues by acidic water and could, therefore, have heavily contaminated mains water after the incident. However, analyses of residents' plasma and whole blood, and of urine following a lead-chelation test, showed no evidence of either long-term increased 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 pollution, some residents who consumed mains water would have been acutely exposed 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 lead are not anticipated.(ABSTRACT TRUNCATED AT 250 WORDS)