Exposure to Lead

Everything You'd Ever Want to Know About Lead and Your Health

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MAJOR SOURCES OF EXPOSURE

The major sources of lead exposure are:

bulletBreathing air containing lead: Lead in air comes from multiple sources, including the burning of leaded fossil fuels; lead smelting, refining and manufacturing industries; and tobacco smoke. bulletIngestion of lead-based paints: These paints may result in high levels of lead both indoors and outdoors as the paints age and degrade. Ingestion of lead-based paint chips is especially dangerous to infants and young children. bulletDrinking water which has passed through lead pipes or lead soldered fittings. bulletBreathing or ingesting contaminated soil, dust, air or water near waste sites, which frequently contain lead; bulletEating food grown on soil which contains lead, or which is covered with lead-containing dust, or which has been stored in tins containing lead solder. bulletOccupational exposure (occupational exposure is particularly common in lead-acid battery manufacturing and recycling; shipbuilding; iron processing; painting, resurfacing and demolition of steel structures; radiator manufacture and repair; scrap metal; firing ranges; fishing weight production; leaded glass manufacturing; lead ore production and smelting; recycling operations). horizontal rule

HEALTH EFFECTS OF LEAD EXPOSURE IN HUMANS

Lead poisoning is a particularly insidious public health threat because people exposed to harmful levels of lead usually do not show immediate or clear symptoms of such exposure. Consequently, standards to control absolute toxicity cannot be set as there is no reference dose (RfD). In addition, since lead is pervasive and exposure to lead very common, no true "control" group exists for sensitive populations such as young children, and an exposure threshold for health effects cannot be identified at present. It is probable that no safe exposure level exists for lead since even limited exposure levels have been linked to some health threats.

Although lead has no biological function in humans it is readily absorbed through the gut and persists in both blood and bone. The amount of lead absorbed from the gastro-intestinal tract of adults is typically 10-15% of the ingested quantity; for pregnant women and children, the amount absorbed can increase to as much as 50%. The quantity absorbed increases significantly under fasting conditions and in people suffering from iron or calcium deficiency.

Once in the blood, lead is distributed primarily among three compartments -- blood, soft tissue (kidney, bone marrow, liver and brain), and mineralizing tissue (bones and teeth). Mineralizing tissue contains about 95% of the total body burden of lead in adults. The rate of lead uptake decreases as the dose increases, and a healthy diet can help reduce the absorption of ingested lead.

For additional information on the risks which lead can pose to human health, consult:

* EPA/600/D-86/185 Lead Exposures in the Human Environment (1986)-- Overview on lead exposure in humans; describes how exposure sources of environmental lead are determined; discusses how an exposure baseline is estimated and how other factors may then be added to complete an estimate for lead exposure. This publication may be ordered from EPA's National Center for Environmental Publications and Information (NCEPI).

* EPA/440/4-85/010 "Exposure and Risk Assessment for Lead" (1985)-- This document contains a risk assessment for lead based on U.S. data. Areas studied include identification of lead releases to the environment during production, use or disposal of lead-containing substances; the fate of lead upon entering the environment; and ambient levels to which different human populations and aquatic life are exposed. Exposure levels are estimated and toxicity data available are presented and interpreted. Information on these different areas is then combined to assess the risks of lead exposure to various sub-populations. This publication may be ordered from EPA's National Center for Environmental Publications and Information (NCEPI).

For on-line information from EPA on the health effects of lead and lead compounds, refer to the Health Effects Notebook for Hazardous Air Pollutants:

http://www.epa.gov/ttn/uatw/hlthef/lead.html


Also see the EPA Office of Emergency and Remedial Response's site entitled "Lead and Human Health":

http://www.epa.gov/oerrpage/superfund/web/oerr/ini_pro/lead/lead.htm


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This page was updated on 23-Mar-2017