| Introduction Lead affects virtually every system in the body, but it is particularly harmful to the developing brain and nervous system of fetuses and young children.(1,2) The main effects in exposed individuals include learning deficits and disruptive behavior. Diagnosis is made by obtaining a blood sample and measuring blood lead. However, lead exposure is not easy to recognize, because most poisoned children and adults have no clinical symptoms; as a result, the vast majority of cases are undiagnosed and untreated.(1) The potential for lead absorption by children is five- to tenfold higher than for adults.(2) An additional critical fact is that the provisional Total Tolerable Daily Intake(3) (TTDI) for children (6 years and younger) is 6 mcg of lead. Given that adults absorb and retain about one-fifth to one-tenth as much lead as do children,(4) the corresponding TTDI for adults is about 30 to 60 mcg of lead. For these reasons, the focus of the public health campaign to reduce lead exposure has shifted to prevention; that is, to eliminating the sources of exposure.(5) Some hair care products sold in pharmacies contain lead acetate. Given the well-known dangers of exposure to lead, one would expect to find information about the health risks posed by hair products containing lead acetate. Indeed, during the 1970s researchers raised questions about the safety of these products.(6,7) The focus of the research was skin absorption of lead acetate, and evidence of absorption and redistribution of lead was found. However, 20 years later a review of lead acetate by Cohen and Roe found that hair coloring agents containing lead acetate "can be regarded unequivocally as being toxicologically insignificant."(8) In their review, particular attention was given to theabsorption of lead through the skin, and this route of exposure to lead salts is not sufficient to be a reason for concern. In fact, lead acetate is permanently listed as a cosmetic color additive and is exempt from certification by the Food and Drug Administration (FDA) (the case was closed on this product as of March 1992).(9) To sort out these divergent opinions, this study evaluated hair coloring agents as a household cosmetic product. The study posed the following questions: What is the lead quantity and bioavailability of the chemical form of the products? What is the risk of lead exposure from hair coloring cosmetics in the home environment? Two evaluations were conducted: First, the amount of lead was measured in sample brands both with and without lead acetate. Second, for those brands that contain lead acetate, the products were applied on the hair of subjects as directed, and wipe samples were taken to measure the amount of lead on hands and on other surfaces to evaluate the risk of lead exposure from these surfaces. |
