Fact Sheet: Lead
Population at risk: 26 million
Estimated DALYs (Disability Adjusted Life Years): 9 million years
Lead (Pb) is a heavy metal that occurs naturally in the environment and has been mined for use in a variety of products, including paint, dyes, ceramic glazes, pesticides, ammunition, pipes, weights, cable covers, car batteries and sheets used for protection from radiation. Lead is often combined with other metals to form alloys and until recently, was used worldwide as a gasoline additive to make engines more efficient by improving octane ratings.
Despite its beneficial use in the production of multiple items, exposure to lead can have deleterious effects on human health. Levels of lead in the environment have been increasing for hundreds of years, but it has only been in the past century that the health impacts from lead exposure have been noticed and examined, particularly in children.
One of the most common sources of lead exposure in low- and middle-income countries (LMICs) is from used lead-acid battery (ULAB) recycling. Other common industries associated with releases of lead include mining, primary and secondary metal smelting, steel and iron production and pigment production.
Pure Earth estimates that approximately 26 million people are at risk for exposure to lead globally, with an estimated burden of disease of 9 million DALYs. As of 2015, the Toxic Sites Identification Program has identified nearly 800 sites around the world where exposure to lead threatens the health of the population. Pure Earth continues to develop methodologies for estimating the number of unscreened sites where pollution from lead and other toxic pollutants may threaten the health of the population. In doing so, a more accurate burden of disease caused by lead and other pollution may be understood.
Pathways & Route of Exposures
Lead can be released into the air during its production, processing and recycling phases. After lead settles on soil through precipitation or as particulates, it adsorbs to soil particles that can be blown around and endanger nearby populations. Lead particles can also settle onto nearby surface water bodies and contaminate groundwater sources used for drinking. Contaminated soil and water sources may in turn contaminate food sources, as lead has been shown to accumulate in plants and animals that live and feed in contaminated areas.
Individuals are exposed to lead primarily through ingestion and inhalation of lead-contaminated materials. Lead has also been shown to transfer between an exposed mother and her child while pregnant (in utero) and through breastfeeding. Absorption through the skin is another possible route of exposure. However, this pathway does not often lead to high lead levels. Once lead has entered the body, it can transfer into soft tissues and organs and eventually be stored in bones and teeth for up to 30 years.1 As a result, teeth have been used in some studies to determine levels of lead exposure from both chronic and acute exposure to high doses.2 More commonly, the analysis of blood samples is used for assessing lead exposure, resulting in a blood lead level (BLL) value indicating blood lead content in micrograms per deciliter.
Lead exposure can have both acute and chronic health effects. Children who are exposed to lead are particularly at risk for adverse health effects due to their smaller mass and the inhibition of ongoing developmental processes resulting from exposure. As a result, exposures to very small amounts of lead have been associated with long-term neurological and cognitive defects in children. Fetuses are also very susceptible to adverse health effects from lead exposure, and may develop birth defects. As a result, the Centers for Disease Control (CDC) recently decreased the level of concern for children regarding lead exposure from a BLL of 10 μg/dL to 5 μg/dL.3
Some of the overall adverse health impacts from lead include neurological damage, intelligent quotient (IQ) decrement, anemia, muscle and joint pain, loss of memory, decreased concentration, nerve disorders, infertility, increased blood pressure and chronic headaches. At very high doses, lead exposure can also result in seizures and death.
Exposure to doses of lead over a long period of time can result in detrimental health effects. The danger of lead exposure was highlighted in Dakar, Senegal in November 2007 and March 2008 when 18 children died of acute lead poisoning. The children were exposed to lead dust and contaminated soil from the community’s main economic activity, ULAB recycling. Blood analyses of the children from the area revealed the average blood lead level to be 129.6 μg/dL, significantly higher than what is recommended by the CDC.4 Furthermore, a study conducted by Caravanos et al (2014) estimated the impact of lead exposure on IQ in rural and urban Mexico, where leaded glaze is commonly applied to pottery and cookware. Results from the study predicted that 15% of the total population would experience a decrement of 5 or more IQ points due to lead exposure.5
From The Pollution Blog: What is the #1 Environmental Health Threat Globally?
1 U.S. Department of Health and Human Services Agency for Toxic Substances and Disease Registry. Toxicological profile for lead. Agency for Toxic Substances and Disease Portal Web site. http://www.atsdr.cdc.gov/toxprofiles/tp13.pdf. Published August 2007. Updated 2007. Accessed October 1, 20152
2 Hodgson S, Manmee C, Dirks W, Shepherd T, Pless-Mulloli T. Determinants of childhood lead exposure in the postleaded petrol era: The tooth fairy cohort from newcastle upon tyne. Journal of Exposure Science and Environmental Epidemiology. 2014
3 Centers for Disease Control and Prevention (CDC). Blood lead levels in children. CDC’s Childhood Lead Poisoning Prevention Program Web site.http://www.cdc.gov/nceh/lead/acclpp/lead_levels_in_children_fact_sheet.pdf. Published 2012. Updated 2014. Accessed October 1, 2015
4 Haefliger P, Mathieu-Nolf M, Lociciro S, et al. Mass lead intoxication from informal used lead-acid battery recycling in Dakar, Senegal. Environ Health Perspect. 2009;117(10):1535-1540
5 Caravanos J, Dowling R, Téllez-Rojo MM, et al. Blood lead levels in Mexico and pediatric burden of disease implications. Annals of Global Health. 2014;80(4):269-277