Distinguishing between Natural and Industrial Lead in Consumer Products and Other Environmental Matrices

California’s Safe Drinking Water and Toxic Enforcement Act of 1986 (Proposition 65) was designed to protect the state's populace from exposures to toxic levels of chemicals in consumer products, including foods, by requiring businesses to warn the public about any of those hazards. There is, however, one qualification in the legislation, which is that warnings are not required if the source of that contamination is natural – as opposed to industrial. That qualification is especially problematic for lead because “natural” and “industrial” lead have a common origin, behave the same in the environment, and industrial lead contamination has been pandemic for millennia. As a result of that historic and on-going contamination, ambient lead levels in the biosphere may be orders of magnitude above natural levels, limiting comparisons of “natural” v. “industrial” lead concentrations in products. Further complicating those comparisons are reports of erroneously high measurements of lead concentrations in the biosph...