The major remaining cause of lead poisoning is lead-based paint in housing, especially housing built before 1950, when lead paint was commonly used. Most children with elevated lead levels are poisoned in their own homes by peeling lead-based paint and the lead dust it generates. The mere presence of lead-based paint in a home is not a hazard, as about 40 percent of all U.S. housing contains some leaded paint, and the vast majority of children live safely in these homes and apartments.
Housing age is an important predictor of risk, because the lead content of paint varied substantially over the past century. During the first half of the twentieth century, the lead content of paint was marketed as a measure of its quality—the more lead the better. Prior to about 1940, leaded paints typically contained high amounts of lead, ranging from 10 percent to as much as 50 percent. Lead was added to make paint durable, so lead paint was frequently used in high-traffic and high-moisture areas, including kitchens and bathrooms, exterior siding and trim, window and door trim, stairs, porches, etc. In the early 1950s, the paint industry began reducing lead content, although many paints still contained harmful amounts of lead. Federal regulations limited lead content in 1972 and effectively banned lead in residential paints in 1978.
Two situations account for the vast majority of poisoning in children. Most commonly, children are poisoned by lead dust from deteriorated paint in poorly maintained older housing. A lesser number of cases—though often more serious—are caused by repainting and remodeling projects that disrupt old painted surfaces without proper safeguards to control, contain, and clean up lead dust. In both scenarios, small amounts of lead dust can create substantial health risks. For example, imagine the amount of sugar in a 1-gram packet. The same amount of lead particles evenly spread over 100 rooms, each measuring 10 feet by 10 feet, would leave dust levels of 100 µg/ft2, an amount of lead that is more than twice the federal standard (40 µg/ft2) for a hazardous level of lead on floors.
Lead in soil can come from many sources, including exterior lead-based paint that is peeling or flaking, dust or paint chips resulting from repainting or renovation projects, deposition from emissions of vehicles that used leaded gasoline, and demolition of buildings with lead-based paint. The U.S. Geological Survey estimates the mean naturally occurring lead in soil concentration to be 16 parts per million (ppm). EPA defines a soil lead hazard as 400 parts per million (ppm) in play areas and a 1,200 ppm average for bare soil in the rest of the yard.
Drinking water may become contaminated with lead from pipes or solder leached out by corrosion. EPA estimates that drinking water accounts for 10 to 20 percent of human exposure to lead. Infants may be put at increased risk from lead in drinking water when contaminated tap water is used to make baby formula. EPA recommends that action be taken if more than 10 percent of tap water samples exceed the action level of 15 parts per billion.
Primary prevention of lead exposure, including testing for lead content in paint, soil, and water; housing maintenance; and remediation of existing hazards is key to protecting children’s health. Lead poisoning is a concrete expression of the affordable housing crisis, more prevalent among poor children, children of color, and those living in older housing. Responsible property management, the need for enforceable housing quality standards that are both practical and cost-effective, and increased resources are needed to protect high-risk communities and preserve the nation’s affordable housing stock.
Sources and Additional Information:
U.S. Department of Housing and Urban Development Office of Healthy Homes and Lead Hazard Control – www.hud.gov/offices/lead/
Environmental Health Perspectives, The Prevalence of Lead-Based Paint Hazards in U.S. Housing – www.hud.gov/offices/lead/techstudies/LeadPaintHousingSurvey.pdf