Lead in calcium supplements

Intercalibrated measurements of lead in calcium supplements indicate the im portance of rigorous analytical techniques to accurately quantify contamina nt exposures in complex matrices. Without such techniques, measurements of lead concentrations in calcium supplements may be either erroneously low, b y as much as 50%, or below the detection limit needed for new public health criteria. In this study, we determined the lead content of 136 brands of s upplements that were purchased in 1996. The calcium in the products was der ived from natural sources (bonemeal, dolomite, or oyster shell) or was synt hesized and/or refined (chelated and nonchelated calcium). The dried produc ts were acid digested and analyzed for lead by high resolution-inductively coupled plasma-mass spectrometry. The method's limit of quantitation averag ed 0.06 mu g/g, with a coefficient of variation of 1.7% and a 90-100% lead recovery of a bonemeal standard reference material. Two-thirds of chose cal cium supplements failed to meet the 1999 California criteria for acceptable lead levels (1.5 mu g/daily dose of calcium) in consumer products. The non chelated synthesized and/or refined calcium products, specifically antacids and infant formulas, had the lowest lead concentrations, ranging from nond etectable to 2.9 mu g Pb/g calcium, and had the largest proportion of brand s meeting the new criteria (85% of the antacids and 100% of the infant form ulas).