Causes and Risk Factors of Lead Poisoning

Despite laws eliminating lead from products such as paint and gasoline, there remains a continued risk of lead exposure and poisoning in the United States.

There has been no better example of this than a 2016 crisis in Flint, Michigan in which over 100,000 residents were exposed to lead due to outdated plumbing in the public water system and insufficient water treatment facilities. In the year following the crisis, no less than 5 percent of the children screened had high levels of lead in their body.

Lead exposure can occur from contact with lead in the air, household dust, soil, water, and commercial products. Continued exposure over the course of months or years can eventually lead to lead poisoning.

lead poisoning causes and risk factors
© Verywell, 2018 

Risk Factors

According to a report from the Centers for Disease Control and Prevention (CDC), children are at the greatest risk of lead poisoning for several reasons:

  • They are more likely to ingest lead particles due to hand-to-mouth behaviors.
  • They absorb ingested lead more readily than adults do.
  • They have a faster respiration rate and inhale more airborne particle by body mass.
  • They are closer to the ground and are more likely to inhale particles in the soil or on the ground.

Other factors can place both adults and children at risk. Chief among them is living in an unrenovated building built before 1978 (the year when lead was officially banned from paint products).

This factor alone translates to a higher risk of lead poisoning among poor, ethnic communities where substandard housing is commonplace. In fact, according to the CDC, African-American children are four times more likely to get lead poisoning than white children. 

Here are eight most common sources of lead exposure in the United States:

Paint

Paint may be the most recognized source of lead exposure in the United States. According to a report issued by the U.S. Environmental Protection Agency (EPA), the risk is significant in any home built before 1978 and tends to increase the older the house is. 

The EPA findings suggest that:

  • 24 percent of houses built between 1960 and 1977 still have leaded paint somewhere in the building
  • 69 percent of houses built between 1940 and 1959 will have evidence of leaded paint
  • 87 percent of houses built before1940 will are likely to have leaded paint in them

The hazard of exposure is greatest wherever old paint is peeling, chipping, chalking, cracking, or damp. This is especially true around window frames, doors, railings, porches, and banisters where hands can more readily pick up paint chips and particles.

While lead paint buried beneath new paint is not a problem, any home renovation that involves the scraping of plaster or paint can provide an opportunity for exposure. While wet mopping, vacuuming, and face masks can greatly reduce the risk, the EPA recommends that you remove any children or pregnant women from the home until the renovations are complete.

Soil

Lead is a naturally occurring metal identified by its bluish-gray coloration. While it can readily be found in nature, its concentration in soil is generally low and not considered a hazard.

The same does not apply to urban soil that had been contaminated with peeling paint from older houses or buildings. Soils adjacent to heavy traffic areas are also a concern, with some studies suggesting that between four and five million tons of lead used in gasoline still remain in soil and dust.

If your house is older, the EPA recommends that you check the exterior for flaking or deteriorating paint. If there is any, you can avoid tracking soil inside by using doormats inside and outside of the house and removing your shoes before entering.

If you can't afford to repaint your home, you should consider planting bushes close to the house, so that kids are discouraged from playing in the soil.

Water

While lead is not usually found in lakes and other natural water supplies, it can enter the water supply and household plumbing if older pipes are not replaced and begin to corrode. This is even true if the pipes themselves are not made of lead.

Up until 1986, metal pipes were commonly joined using leaded solder. So, even if the pipes themselves contain less than 8 percent lead (the acceptable threshold under the current law), the solder used to connect them could have inordinately high levels of lead. Unless the water is tested, there is really no way to know.

There are other sources of lead in our water that also get missed. One such example is drinking fountains in older schools which are not subject to inspection in many states. In 2017, a San Diego grade school discovered this only after a therapy dog refused to drink water from a fountain.

Even with increased efforts to surveil the public water supply, the EPA says that drinking water makes up around 20 percent of a person's exposure to lead.

Ceramics and Crystal

Some paints and glazes used to decorate pottery and ceramics contain significant levels of lead and, as such, are not intended for use on dinnerware or serving dishes. When food or drinks are placed in them, lead can readily leach out and be ingested.

This is especially true of older pottery and ceramicware that are more likely to have areas of chipping and deterioration. Of particular concern is imported traditional pottery which may be labeled "lead-free" but still contain excessive levels of the extractable metal. A 2010 warning issued by the U.S. Food and Drug Administration advised consumers of the risk after high levels of lead were found in imported ceramicware from Mexico.

Leaded crystal is also a concern. Decanters are especially problematic since wine, liquor, and acidic juices can promote the transfer of lead to the decanted fluid. If you have leaded glassware, the EPA advises against using it either on a daily basis or for the storage of foods or liquids.

Traditional Medications and Comestibles

Traditional medicines should warrant concern as they are largely unregulated in the United States.

Ayurvedic medications and folk remedies imported from India, Southeast Asia, the Middle East, the Dominican Republic, and Mexico are of special concern as there are no means to assess how the ingredients were sourced, how they may have been refined or treated, and under what conditions they were manufactured.

In fact, lead, sulfur, arsenic, copper, and gold are intentionally added to many Ayurvedic remedies under the belief that they offer health benefits, say researchers from the Yale University School of Medicine.

Among the folk medicines that the CDC has identified as having a high risk of lead exposure:

  • Azarcon and greta are Hispanic traditional medicines taken for an upset stomach.
  • Ba-baw-san is a Chinese herbal remedy used to treat colic.
  • Daw tway is a digestive aid used in Thailand and Myanmar.
  • Ghasard is an Indian folk medicine used as a tonic.

Moreover, it's not just medications that are suspect; imported candies and cosmetics are also a concern.

Imported candies from Mexico, Malaysia, China, and India (especially those flavored with tamarind, chili powder, or certain salts) should be avoided as these frequently have elevated levels of lead. The same applies to traditional cosmetics, such as Kohl used in parts of the Middle East, North Africa, and Southeast Asia to outline the eyes.

Even imported everyday cosmetics like lipsticks and eyeliners should be avoided as they are not subject to the strict pre-market testing prescribed under the U.S. Federal Food, Drug, and Cosmetic Act.

Occupations and Hobbies

According to the EPA, the majority of lead poisoning cases in adults are a result of workplace exposure. Among some of the industries in which the risk of lead exposure is high:

  • Auto body repair and repainting
  • Ammunition and bullet manufacturing
  • Battery manufacturing and recycling
  • Construction (particular restoration or retrofitting)
  • Firing range instruction
  • Glass or crystal manufacturing
  • Lead smelting
  • Lead weight manufacturing
  • Meal recycling
  • Mining
  • Pewter manufacturing
  • Plumbing and radiator repair
  • Shipbuilding
  • Steel welding

Hobbyists who engage the following activities are also at risk:

  • Artistic painting
  • Auto repair
  • Electronics soldering
  • Glazed pottery making
  • Metal soldering
  • Molding of bullets, slugs, or fishing sinkers
  • Stained-glass making
  • Shooting firearms

Anyone who engages in these professions or activities can potentially bring lead into their homes. It is important, therefore, to reduce the exposure of risk by showering and changing your clothes and shoes before entering the home or touching family members. 

Toys

Toys manufactured in countries where the use of lead is not restricted may also pose a risk. The worrying part is that there is often little way of knowing whether an imported toy is safe since there are no systems in place to routinely screen them.

With that being said, since new import regulations were enacted by the U.S. Product Safety Commission in 2008, the number of lead-related toy recalls has dropped from 19 in 2008 to zero in 2017.

But, it's not just imported toys that are of concern. Antique toys, lunchboxes, and even old crayons may contain excessive amounts of lead. As such, it may be better to keep these objects in a display case or to throw them out if they are not considered a keepsake.

Pregnancy

When lead gets into your body, it can accumulate in many tissues, including those of the brain, intestines, kidneys, liver, and bones.

During pregnancy, lead deposits in the bones can be especially problematic as metabolic changes can trigger the transient bone loss of the hip. If this happens, lead can leach out into the system and raise the toxicity to hazardous levels. Babies exposed to lead while in the womb are at risk of low birth weight, preterm birth, and even miscarriage.

The daily use of a calcium supplement during pregnancy may greatly counteract the effect.

How Lead Poisoning Is Diagnosed
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