LEACHABILITY OF LEAD FROM SELECTED COPPER-BASE ALLOYS

The Bureau of Mines has conducted research on the selective leaching of lead from copper-base alloys in high-purity water. The alloys in this study were selected as representatives of those used in various plumbing system fixtures such as faucets and valves. Leaching tests were conducted for a total period of 14 days and at temperatures of 25, 50, and 75-degrees-C. An acetic acid pretreatment was used in an effort to reduce the amount of lead that was leached from the alloys. The results show that, with the exception of the more complex yellow brasses, more lead is leached into water from alloys containing greater concentrations of lead and that the rate of lead leaching decreases with exposure time. Higher temperatures had relatively little effect on the leaching of lead. Lead was preferentially dissolved from all of the alloy groups. Of the small total amount of alloy dissolved, more Pb, 10 to 59 times, was dissolved than would be predicted from the proportional quantity of Pb present in the alloy (0.1 to 7.0 wt% Pb). Typically, the amount of Pb dissolved in any given test period exceeded the Environmental Protection Agency proposed action limit of 0.015 mg/L.