Lead in the Inner Cities: 1. Introduction

Policies to reduce children's exposure to lead may be overlooking a major source of lead in the environment

In the middle of the 1970s, U.S. health officials identified what some called a “silent epidemic.” They were referring to childhood lead poisoning, a problem that is easily overlooked and underappreciated. Of all of the metal-poisoning episodes to date, none has come close in sheer numbers. Toxicology textbooks mention cadmium poisoning in Japan in the 1950s and methyl mercury poisoning in both Japan in the 1950s and Iraq in 1972. Some hundreds of deaths were attributed to each of these events. But most textbooks fail to mention lead poisoning, in spite of the fact that since the 1920s millions of American children have been quietly poisoned by lead, and thousands of deaths are attributed to this over the long term.

Although childhood lead exposure has diminished over the past 20 or so years, the problem has by no means been solved. Rather, the demographics have shifted. Some groups, mainly minority and poor children living in the inner city, suffer from high rates of lead poisoning. Over 50 percent (some studies place this figure at around 70 percent) of children living in the inner cities of New Orleans and Philadelphia have blood lead levels above the current guideline of 10 micrograms per deciliter (micrograms per deciliter). In contrast, in the concrete jungle of Manhattan, where very little of the soil is exposed and almost all apartments and housing contain lead-based paints, between 5 and 7 percent of children under the age of 6 have been reported to have blood-lead levels of 10 micrograms per deciliter or higher. Interestingly, just across the river in Brooklyn, where yards containing soil are common, the percentage of affected children is several times higher.

Exposure remains such a problem that early in the 1990s, the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta called lead poisoning “one of the most common pediatric health problems in the United States today,” but added that the problem was “entirely preventable.” Effective prevention, however, assumes an accurate identification of the environmental reservoirs of lead.

Current policies to reduce lead exposure are based on the assumption that the greatest lead hazard comes from lead-based paints. Poorly maintained paints decay and release lead on their surfaces in the form of dust. In addition, lead tastes sweet, and young children may be tempted to eat leaded paint chips as though they were candy. The health consequences of this can be severe. Lead is a neurotoxin that can be especially dangerous to the developing nervous systems of infants and young children. To deal with this problem, most lead paints have been removed from the market, some lead paints are being stripped off of walls, and parents are instructed to guard their children from eating paint flakes.

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Figure 1. Lead additives were used in gasoline for over 50 years until they were banned in 1986. Although lead is no longer allowed in most gasoline products, the legacy of its use remains embedded in soils along roadways and in U.S. cities. Where there is a long history of traffic congestion, such as in the inner cities of many urban areas, lead accumulations are especially high in the soils. Children who live in these areas and play in these soils are particularly vulnerable to lead poisoning. Some simple and relatively inexpensive methods can be used, says the author, to reduce children’s exposure to this environmental toxin. (Except where noted, photographs are courtesy of the author.)

But such policies deal with only part of the lead hazard. Work done in my laboratory demonstrates that there exist additional sources of lead in the environment that pose as great, if not greater, threats to children. To be sure, lead paint is a major contributor of the lead in the environment. Lead was used in residential paint between 1884 and 1978 and remains on the walls of many older buildings. But paint is neither the most abundant nor the most accessible source of lead. The common problem is lead dust. For most children the issue is whether there is a source of lead dust in the environment. Research in my laboratory and others shows that in predictable locations of many cities, the soil is a giant reservoir of tiny particles of lead. This means that many children face their greatest risk for exposure in the yards around their houses and, to a lesser extent, in the open spaces such as public playgrounds in which they play. My colleagues and I believe that an accurate and complete appreciation of the distribution of lead in the environment can help shape policies that more effectively protect the health of children.

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Figure 2. Bare soils in play areas, especially those near busy roads, constitute one of the most common vectors by which children become poisoned. Children play in these soils, put their hands in their mouths, or touch objects that do, and ingest the lead. Children are most vulnerable to the toxic effects of lead, which include damage to the nervous system, learning impairments and behavioral problems.

*Howard Mielke is a professor at the College of Pharmacy of Xavier University in New Orleans. He served as a Peace Corps Volunteer in Malawi, Africa, before obtaining his M.S. in biology and his Ph.D. in geography at the University of Michigan. He began his urban lead research in 1971 while teaching at the University of California, Los Angeles, and continued these studies at the University of Maryland, Baltimore County, and later at Macalester College in Minnesota. Mielke serves as the program director, and is a principal investigator of a multimedia study of metals in the urban and rural environment, for the Substance Specific Applied Research Program as part of a cooperative agreement with the Minority Health Professions Foundation/Agency for Toxic Substances and Disease Registry. He is a corresponding member of the Working Group on Geoscience and Health, Commission on Geological Sciences for Environmental Planning of the International Union of Geological Sciences. Address: Xavier University of Louisiana, College of Pharmacy, 7325 Palmetto Street, New Orleans, LA 70125. Internet: hmielke@mail.xula.edu.

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