Human Health and Lead
For links to information on preventing lead poisoning, please refer to the Related Links page.
- Lead in the Environment
- Possible Ways to be Exposed to Lead
- Symptoms of Lead Exposure
- Medical Tests for Lead Exposure
- Recommendations from the Federal Government
- Frequently Asked Questions
Lead in the Environment
Lead is a naturally-occurring element that can be harmful to humans when ingested or inhaled, particularly to children under the age of six. Lead poisoning can cause a number of adverse human health effects, but is particularly detrimental to the neurological development of children. To learn more about the effects of lead poisoning and EPA's role in reducing the presence of lead in the environment, visit EPA Lead.
For hundreds of years, lead has been mined, smelted, refined, and used in products (e.g., as an additive in paint, gasoline, leaded pipes, solder, crystal, and ceramics). Natural levels of lead in soil range between 50 parts per million (ppm) and 400 ppm. Mining, smelting, and refining activities have resulted in substantial increases in lead levels in the environment, especially near mining and smelting sites. For example, near some types of industrial and municipal facilities, and adjacent to highways (Chaney et al., 1984; Shacklette et al., 1984) soil lead concentrations have been reported to be more than 11,000 ppm (National Research Council, 1980).
Lead particles in the environment can attach to dust and be carried long distances in the air. Such lead-containing dust can be removed from the air by rain and deposited on surface soil, where it may remain for many years. In addition, heavy rains may cause lead in surface soil to migrate into ground water and eventually into water systems.
Possible Ways to be Exposed to Lead
Everyone is exposed to "background levels" of lead, given its widespread distribution. Possible routes of lead exposure include:
- ingestion of lead-contaminated water, soil, paint chips, or dust;
- inhalation of lead-containing particles of soil or dust in air; and
- ingestion of foods that contain lead from soil or water.
Symptoms of Lead Exposure
Lead poisoning can be a serious public health threat with no unique signs or symptoms. Early symptoms of lead exposure may include:
- persistent fatigue
- loss of appetite
- stomach discomfort and/or constipation
- reduced attention span
Failure to treat lead poisoning in the early stages can cause long-term or permanent health damage, but because of the general nature of symptoms at early stages, lead poisoning is often not suspected.
In adults, lead poisoning can cause:
- poor muscle coordination
- nerve damage to the sense organs and nerves controlling the body
- increased blood pressure
- hearing and vision impairment
- reproductive problems (e.g., decreased sperm count)
- retarded fetal development even at relatively low exposure levels
In children, lead poisoning can cause:
- damage to the brain and nervous system
- behavioral problems
- liver and kidney damage
- hearing loss
- developmental delays
- in extreme cases, death
Although the effects of lead exposure are a potential concern for all humans, young children (less than seven years old) are most at risk (Reagan and Silbergeld, 1989). This increased vulnerability results from a combination of the following factors:
- Children typically have higher intake rates (per unit body weight) for environmental media (such as soil, dust, food, water, air, and paint) than adults, since they are more likely to play in dirt and put their hands and other objects in their mouths;
- Children tend to absorb a higher fraction of ingested lead from the gastrointestinal tract than adults;
- Children tend to be more susceptible than adults to the adverse neurological and developmental effects of lead; and
- Nutritional deficiencies of iron or calcium, which are common in children, may facilitate lead absorption and exacerbate the toxic effects of lead.
The national average blood lead levels in children have dropped over time as our understanding of lead risk has evolved, and as efforts are undertaken to reduce exposure to lead. While banning of lead paint and lead in gasoline were national efforts to stop childhood lead poisoning, contaminated sites require site-specific cleanups to reduce exposure to populations nearby.
The Centers for Disease Control (CDC) has identified that the current blood lead level of concern in children is 10 micrograms (µg) of lead per deciliter (dL) of blood (10 µg/dL); however, adverse effects may occur at lower levels than previously thought. In January of 2012, an advisory panel to the CDC recommended lowering the level that triggers intervention.
Medical Tests for Lead Exposure
If you have concerns about possible lead exposure, contact your personal physician or county/state health department. Your doctor can conduct blood tests to determine lead concentrations in your blood. Blood tests are inexpensive and sometimes free; however, please consult your insurance provider to determine coverage of such tests. Lead in bone and teeth can be measured using x-ray techniques, but this test is not used very often. In communities where houses are old and deteriorating, residents are encouraged to take advantage of available screening programs offered by local health departments and to have children living in the residence checked regularly for lead poisoning. Because the early symptoms of lead poisoning are similar to those of other illnesses, it is difficult to diagnose lead poisoning without medical testing.
Recommendations from the Federal Government
The CDC recommends that screening for lead poisoning be included in health care programs for children under 72 months of age. This screening is especially critical for children under 36 months of age. Screening should start at six months of age if the child is at risk for lead exposure (e.g., if the child lives in a home built before 1960, with peeling or chipping paint). Decisions about further lead testing should be based on previous blood-lead test results, and the child's risk of lead exposure. In some states, more frequent lead screening is required by law.
To help protect small children who might swallow paint chips, the Consumer Product Safety Commission (CPSC), does not allow the amount of lead in most paints to exceed 0.06 percent. The CDC suggests testing paint on the inside and outside of residential buildings for lead.The CPSC, EPA, and states are required by the 1988 Lead Contamination Control Act to test drinking water in schools for lead, and to remove the lead if levels are too high. Drinking water coolers must be free of lead contamination and any water coolers that are tainted with lead have to be removed. EPA regulations limit lead in drinking water to 15 micrograms per liter (15 µg/L).
EPA has established standards designed to limit the amount of lead in ambient air. Over a three-month period, the average concentration of lead (as measured in total suspended particles) cannot be greater than 0.15 micrograms of lead per cubic meter of air (0.15 µg/m3). The National Institute for Occupational Safety and Health (NIOSH) recommends that workers not be exposed to lead levels of greater than 100 µg/m3 for up to ten hours. Because lead can be released into the air with automobile exhaust, EPA limits the amount of lead in unleaded gasoline to 0.05 grams of lead per gallon of gasoline (0.05 g/gal). Lead emissions from automobile exhaust now contribute only marginally to lead levels in the environment, but before leaded gasoline was banned in the United States, exhaust emissions were a significant problem. Lead emitted from past burning of leaded fuel is still present in the environment today.
Chaney, R.L. et al. 1984. The potential for heavy metal exposure from urban gardens and soils, pp. 37-84. In: J.R. Preer ed. Proceedings of the symposium on heavy metals in urban gardens. Agricultural Experiment Station, University of the District of Columbia, Washington.
Reagan, P.L. & E.K. Silbergeld. 1989. Establishing a health based standard for lead in residential soils. In: Hemphill and Cothern, eds. Trace substances in environmental health, supplement to Volume 12, (1990) of Environmental Geochemistry and Health.
U.S. EPA. Air Quality Criteria for Lead (2006) Final Report. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-05/144aF-bF, 2006. (http://www.epa.gov/ttn/naaqs/standards/pb/s_pb_cr_cd.html)