Centers for Disease Control and Prevention (CDC) has established 10 µg/dL as the upper limit of acceptable lead levels, mostly because of a lack of studies showing adverse effects of lower levels. Two studies in the April 17 issue of the New England Journal of Medicine provide new evidence for establishing a lower limit. The first demonstrates that an increase from 1 to 10 µg/dL is proportionately associated with cognitive decline, and the second is a cross-sectional study showing delayed puberty for levels of only 3 µg/dL. A recent study reported by Medscape also showed that higher lead levels within the "acceptable" range were linked to increased blood pressure in postmenopausal women
In an accompanying editorial, Walter J. Rogan, MD, from the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina, and James H. Ware, PhD, from the Harvard School of Public Health in Boston, Massachusetts, note that eliminating elevated blood lead concentrations by the end of this decade is already a federal objective. Based on these studies, however, "the job may not be finished even when all children have blood lead concentrations below 10 µg/dl.
"The effects of lead exposure appear to be long-lasting and irreversible.
