Lead risk to human
Lead risk to human
Source: United States Environmental Protection Agency
Lead is used in the manufacture of batteries, l products and ammunition. Exposure to lead can occur from breathing contaminated air in or near workplaces that process lead or lead materials, as well as from incidentally ingesting dust or paint chips in houses with lead-d paint. Lead can cause effects on the blood, as well as the nervous, immune, renal and cardiovascular systems. Early childhood and prenatal exposures are associated with slowed cognitive development, learning deficits and other effects. Exposure to high amounts of lead can cause gastrointestinal symptoms, severely damage the brain and kidneys, and may cause reproductive effects. Large doses of some lead compounds have caused cancer in lab animals.
Sources and Potential Exposure
Human exposure to lead occurs through a combination of inhalation and oral exposure, with inhalation generally contributing a greater proportion of the dose for occupationally exposed groups, and the oral route generally contributing a greater proportion of the dose for the general population. The effects of lead are the same regardless of the route of exposure (inhalation or oral) and are correlated with internal exposure, as blood lead levels. For this reason, blood lead levels are often used to characterize exposure.
In the past, the largest source of lead in the atmosphere has been from leaded gasoline combustion, but with the phase-down of lead in gasoline, air lead levels have decreased considerably. Currently, the largest sources of airborne emissions are ls industries, including lead smelters and iron and steel production, manufacturing industries and waste incineration.
Exposure to lead can also occur from food and soil. Children are at particular risk to lead exposure since they commonly put hands, toys, and other items in their mouths, which may come in contact with lead-containing dust and dirt.
Lead-d paints were commonly used until 1978 and flaking paint, paint chips, and weathered paint powder may be a major source of lead exposure, particularly for children.
Lead in drinking water is due primarily to the presence of lead in certain older pipes, solder, and fixtures. A diet that is nutritionally adequate in calcium and iron may decrease the absorbed dose of lead.
Exposure to lead may also occur in the workplace, such as mining, lead smelting and refining industries, steel and iron factories, and battery manufacturing plants.
Lead has been listed as a pollutant of concern to EPA's Great Waters Program due to its persistence in the environment, potential to bioaccumulation, and toxicity to humans and the environment.
Assessing Personal Exposure
Once taken into the body, lead distributes throughout the body in the blood and is accumulated in the bones.
The amount of lead in the blood can be measured to assess exposure to lead.
The level of lead in the blood is measured in micrograms per deciliter (μg/dl).
Exposure to lead can also be evaluated by measuring erythrocyte protoporphyrin (EP), a component of red blood cells known to increase when the amount of lead in the blood is high. This method was commonly used to screen children for potential lead poisoning.
Methods to measure lead in teeth or bones by X-ray fluorescence techniques are not widely available. Such methods are used in research studies to assess cumulative exposure.
Health Hazard Information
Noncancer Effects: ? Studies of humans as well as laboratory animal studies have reported effects on the blood, kidneys, and nervous, immune, and cardiovascular systems.
Ingestion of large amounts of lead can produce gastrointestinal symptoms, including colic, constipation, abdominal pain, anexoria and vomiting.
Severe brain and kidney damage can occur in children after exposures resulting in blood lead levels between 70 and 100 μg/dl and in adults at blood lead levels between 100 and 120 μg/dl.
Anemia has been reported after exposure resulting in blood lead levels of 40 to 70 μg/dl in children and blood lead levels of 50 to 80 μg/dl in adults.
Other effects from chronic lead exposure in humans include effects on blood pressure and kidney function, immune system effects and interference with vitamin D bolism.
Lead also affects the nervous system in occupational-exposed adults. Neurological symptoms have been reported in workers with blood lead levels of 40 to 60 μg/dl, and slowed nerve conduction in peripheral nerves in adults occurs at blood lead levels of 30 to 40 μg/dl.
Children are particularly vulnerable to the neurotoxic effects of lead. Exposure to low levels of lead early in life have been ed to effects on IQ, learning, memory, and behavior.
Exposure to lead during pregnancy has been associated with toxic effects on the human fetus, including increased risk of preterm delivery, low birthweight, and impaired mental development, including decreased IQ scores. These effects on mental development have been noted at maternal blood lead levels of 10 to 15 μg/dl and somewhat lower.
Studies on male lead workers have reported severe depression of sperm count and decreased function of the prostate and/or seminal vesicles and suggests an impact on male fertility at blood lead levels of above 40-45 μg/dl.
Human studies are inconclusive regarding the association between lead exposure and other birth defects, while animal studies have shown a relationship between high lead exposure and birth defects.
Cancer Risk: ? Human studies are inconclusive regarding lead exposure and an increased cancer risk. Animal studies have reported kidney tumors in rats and mice exposed to lead via the oral route.
EPA has considered lead to be a probable human carcinogen, and, under more recent assessment guidelines, it would likely be classified as likely to be carcinogenic to humans.
1. U.S. Environmental Protection Agency. Air Quality Criteria for Lead (2006) Final Report. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-05/144aF-bF, 2006. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=158823#Download
2. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Lead (Update). Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 2007.
3. Agency for Toxic Substances and Disease Registry (ATSDR). Medical Management Guidelines for lead. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 2007.http://www.atsdr.cdc.gov/MMG/MMG.asp
4. U.S. Environmental Protection Agency. Deposition of Air Pollutants to the Great Waters. First Report to Congress. EPA-453/R-93-055. Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1994.
5. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Lead and Compounds (Inorganic). National Center for Environmental Assessment, Office of Research and Development, Washington, DC. Last revised 2004.
6. National Institute for Occupational Safety and Health (NIOSH). NIOSH Pocket Guide to Chemical Hazards. http://www.cdc.gov/niosh/npg/npg.html. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention. Cincinnati, OH. 2007.
7. U.S. Environmental Protection Agency. National Ambient Air Quality Standards for Lead. 73 FR 66964. November 12, 2008.
Lead is extreme harmful to adults. Adults exposed to lead can suffer from:
1.Cardiovascular effects, increased blood pressure and incidence of hypertension;
2.Decreased kidney function;
3.Reproductive problems (in both men and women).
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