Lead Poisoning

Sources of Lead Exposure

Lead is a dangerous threat to global health due to the many possible sources of exposure that vary based on age and geographic location. One source of lead exposure is water, when pipes and/or soldering around pipes used for water transportation are made of lead. Efforts in the U.S. have been made to remove lead plumbing, but doing so is costly and therefore not an option for all.

Another source of exposure is lead-based paint in homes. U.S legislation passed in 1978 banned the use of lead-based paint, but this continues to be an exposure source when paint begins to peel and chip. Paint chips are often found on windowsills, usually at a height accessible to children where the chips can be ingested. Renovations in homes with lead-based paint can release dust into the air placing inhabitants at risk of inhaling the toxin. In metropolitan areas, soil is also a common source of lead exposure among children, a result of exhaust from cars that used leaded gasoline.

Other possible sources of lead exposure include occupations (i.e. lead smelting, lead manufacturing and recycling industries), hobbies (i.e. making pottery, stained glass, and refinishing), folk remedies, and plates, glasses, and cans glazed with lead.

Rates and Changing Definition of “Lead Poisoning”

Over the past four decades every segment of the U.S. population has seen drastic decreases in lead levels due to the removal of lead from gasoline, paint, food and drink cans, and plumbing systems. According to the Centers for Disease Control and Prevention (CDC), average lead levels among children 1 to 5 decreased from 15.0 mcg/deciliter in 1976–1980 to 2.7 in 1991–1994.

Despite declines in lead levels, approximately 1 million children in the U.S have levels associated with adverse effects, with the risk falling disproportionately on children who are poor, non-Hispanic black, [Page 998]Mexican American, and living in large metropolitan areas and in older housing.

As rates have been decreasing so has the CDC's definition of what is an elevated lead level due to advancing knowledge of the effects of lead. Before 1960 intervention was thought unnecessary with levels >60 mcg/dl. In 1960 the definition of lead poisoning dropped to 25 mcg/dl. Not until 1991 did this change when the CDC recommended individualized intervention when 15 mcg/dl or higher, and community efforts initiated with levels of <10. Despite this benchmark, some studies have argued lead levels >10 mcg/dl can be harmful.

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