Which environmental exposures cause lead toxicity?

Updated: Jan 16, 2020
  • Author: Pranay Kathuria, MD, FACP, FASN, FNKF; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Exposure from lead-based paint was significant among children in the past. Although lead was banned from use in residential paint, it continues to be used in nonresidential settings, and as a result of its past use, lead paint can still be found in many older homes.

Leaded gasoline contaminates the atmosphere. Although lead has been removed from gasoline in Western countries, leaded gasoline continues to be used in the developing world. Huffing of leaded gasoline (ie, deeply inhaling fumes to achieve a “high”) could also cause poisoning.

Food has been an important source of lead exposure. Surface contamination of homegrown vegetables, storage cans with lead solder seams (banned in 1991), and kitchenware are sources of lead contamination in food. Strong animal evidence suggests that malnutrition is highly significantly associated with increased levels of blood lead. [9]

Water is an important source of lead poisoning. Lead from the atmosphere may contaminate bodies of water [10]  and equally important, the leaching of lead from water pipes may cause poisoning. Although use of lead pipes (largely replaced by copper or polyvinyl pipes) has declined considerably since the 1950s, old public water systems continue to have networks that include lead piping. Because the use of lead-based soldering of copper pipes was permitted until 1986, homes with copper plumbing may also have substantial lead in the water. In May 2015, at least 28 children under the age of five were killed by drinking stream water contaminated with lead in Nigeria's Niger state. [11]

One of the worst public waterworks failures occurred in Flint, Michigan causing widespread lead poisoning. In 2014, Flint changed sourcing water from Lake Huron to the Flint River to save money. The corrosion-control treatments required by the Environmental Protection Agency were not followed for unknown reasons and increased amounts of chlorine were added to the water due to bacterial contamination. This made the water very corrosive and caused leaching of lead from the aging water system pipes. In six of nine city wards, the water in 20% to 32% of the homes had a lead concentration greter than15 μg per liter. The 90th percentile was 25 μg per liter, and in some samples the lead concentration exceeded 1000 μg per liter (www.FlintWaterStudy.org). [4] The incidence of children with elevated blood lead concentrations (greater than the reference value of 5 μg per deciliter) increased from 2.4% to 4.9% between 2013 and 2015. The increase was greatest, from 4.0% to 10.6%, among children in neighborhoods with the highest lead concentrations in water. [12]

Some hobbies are associated with exposures to lead. These hobbies may include making bullets, making fishing-weights, soldering, indoor firearm shooting, and remodeling older homes.

Soil contaminated with lead can be an important source of lead exposure. Such soil contamination may occur surrounding lead smelters and around older homes with deterioration of exterior surfaces.

Moonshine ethanol (ie, illegally distilled corn whiskey) made in lead-containing vessels, such as discarded automobile radiators, has been associated with lead poisoning and even local epidemics. [13]

Topical agents that contain lead, such as kohl and surma, may be ingested accidentally.

Several reports exist of lead poisoning that develops as the result of absorption of lead from retained bullet or shrapnel fragments. Bullets located in areas bathed by fluids are more likely to dissolve, while those embedded in soft tissues are likely to be walled off by inflammation.

An incidental finding of bullet or shrapnel fragments on an x-ray should prompt consideration of possible elevated lead levels, though most of these cases occur only with intra-articular fragments. Of particular concern is a retained bullet in the spine, an area where removal is often considered too dangerous to attempt. [14]

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