Lead release potential of stainless steel plumbing materials – An investigation using leaching experiment

Abstract

Stainless steel (SS) is considered lead-free as lead (Pb) is not one of its components. However, Pb impurities during SS production can be unintentionally introduced. Hence, this study examined the potential and extent of Pb leaching from SS plumbing materials under mild and aggressive conditions. Synthesized tap water represented mild, while an acidic solution (pH 4) of high concentration (100 mg/L) ethylenediaminetetraacetic acid (EDTA) represented aggressive conditions. Leaching experiments were performed with a three-day stagnation, simulating a long stagnation during the weekend for up to 30 days. A dump-and-fill method was used, and total Pb was measured after three days. Pb concentrations in both solutions exceeded the locally regulated standard value of 10 μg/L during initial stagnation in fittings. Pb release from the fittings in EDTA solution peaked at 27 μg/L during the first stagnation, reducing to levels below 10 μg/L after 27 days. Likewise, it reached a maximum of 14 μg/L, diminishing to below 10 μg/L after 12 days in tap water. However, the Pb release from the pipes under both conditions consistently remained below 10 μg/L. This transient release suggests that Pb was most likely a surface contaminant. The results imply that SS can be a potential source of Pb, with the extent of release varying depending on the type of SS plumbing materials used.