Context
Substantial quantities of lead have been reported in some over-the-counter
calcium supplement preparations, including not only bonemeal and dolomite,
but also over-the-counter natural and refined calcium carbonate formulations.
Examination of this issue is warranted given recent increases in physician
recommendations for calcium supplements for prevention and treatment of osteoporosis.
Objectives
To determine the lead content of calcium supplements and to quantify
the lead exposure from popular brands of calcium in dosages used for childhood
recommended daily allowance, osteoporosis, and phosphate binding in dialysis
patients.
Design and Setting
Analysis of lead content in 21 formulations of nonprescription calcium
carbonate (including 7 natural [ie, oyster shell] and 14 refined), 1 brand
of prescription-only calcium acetate, and 1 noncalcium synthetic phosphate
binder conducted in March 2000.
Main Outcome Measures
Lead content, assayed using electrothermal atomic absorption, expressed
as micrograms of lead per 800 mg/d of elemental calcium, per 1500 mg/d of
calcium, and for a range of dosages for patients with renal failure. Six µg/d
of lead was considered the absolute dietary limit, with no more than 1 µg/d
being the goal for supplements.
Results
Four of 7 natural products had measurable lead content, amounting to
approximately 1 µg/d for 800 mg/d of calcium, between 1 and 2 µg/d
for 1500 mg/d of calcium, and up to 10 µg/d for renal dosages. Four
of the 14 refined products had similar lead content, including up to 3 µg/d
of lead in osteoporosis calcium dosages and up to 20 µg/d in high renal
dosages. No lead was detected in the calcium acetate or polymer products.
Lead was present even in some brand name products from major pharmaceutical
companies not of natural oyster shell derivation.
Conclusions
Despite increasingly stringent limits of lead exposure, many calcium
supplement formulations contain lead and thereby may pose an easily avoidable
public health concern.