Childhood Lead Exposure Linked To Lower IQ


Children exposed to high levels of lead decades ago are now approaching middle age with lower IQs than they would have had otherwise, a new study suggests. Lead is a potent neurotoxin and there’s no safe level of lead exposure. This toxin can damage the developing nervous system in young children, and blood lead levels as low as 5 micrograms per deciliter may lower intelligence quotient, according to the World Health Organization.

The Study

The decades-long study published in the Journal of the American Medical Association shows that the effects of lead exposure can be long-lasting. Researchers followed more than 500 persons from New Zealand from birth in the 1970s to adulthood. They then examined data on cognitive function and IQ when the participants were 38 years old, as well as results from blood tests for lead done in childhood. In the seventies, New Zealand had some of the highest gasoline lead levels in the world.

Participants with childhood blood lead levels above 10 micrograms/dl had average adult IQ test scores 4.25 points lower than their peers with lower blood lead levels.

The study suggests that individuals don’t fully recover from lead-related exposure health effects from childhood. Lead decreases individual’s cognitive abilities over time at whatever age it occurs. While lead exposure has long been linked to poor academic achievement, this study offers new evidence of how high blood lead levels in childhood can lead to lower socioeconomic performance in adulthood.

Children with very high blood lead levels were found in the U.S. in at least six regions, including New York, Pennsylvania and Ohio according to a study released last June in the Journal of Pediatrics. And a Reuter investigation of blood testing data in California found multiple communities with unsafe levels of lead in their children.

Effects on IQ are just the tip of the iceberg. The adverse effects can include impaired attention, including ADHD, decrease of executive function, and different forms of social pathologies.

Possible Exposure To Lead

Water Pipes

Lead can enter drinking water through corrosion of plumbing materials. Homes built before 1986 are more likely to have lead pipes, fixtures and solder. However, new homes are also at risk: Before 2014, legally “lead-free” plumbing could contain up to eight percent lead according to the EPA. Brass-based faucets and fixtures with lead solder can release significant amounts of lead into the water.


Home built before 1978 have a good chance to have lead-based paint. Lead paint is still present in millions of homes, sometimes under layers of newer paint. Risk is especially acute when the paint begins to deteriorate. The most common source of lead exposure for children is lead-based paint and the dust and soil that are contaminated by it.

Household Dust

Lead in household dust results from indoor sources such as deteriorating lead-based paint. It can also come from soil outside contaminated by exterior damaged lead paint, industrial pollutants or old leaded gasoline.
Renovation can also release toxic lead dust when painted surfaces are disturbed.


Lead paint and dust can settle into the soil surrounding a painted building, then get easily picked up when it’s walked on or when kids play in it. Lead residues can still be present in soil from old contamination.


Old toys may contain high lead levels that are especially dangerous for children who play with them and might chew on them. Lead has been found in inexpensive children’s jewelry sold in vending machines and large volume discount stores across the country, according to the New York Department of Health.


Food and liquids stored or served in lead crystal or lead-glazed pottery or porcelain can become contaminated because lead can leach from these containers into the food or liquid.

Wild Game

People can be exposed to lead by eating wild animals that were shot and killed with lead bullets. Recent research indicates that small lead fragments are often present in venison from deer harvested with lead bullets, according to the New York Department of Health.

Protect Your Family

The Centers for Disease Control offers helpful suggestions to protect children from lead exposure.

If your home was built before 1978, you can contact your state or local health department to have your home tested for lead. If you’re planning to undergo renovations, it is recommended to have it done by qualified professionals. Children and pregnant women should not be in the house during the renovations to avoid toxic dust.

If you think that you can have lead pollutants outside the house, mop smooth floors and wipe flat surfaces weekly to control dust.

Make sure your child does not have access to peeling paint or chewable surfaces painted with lead-based paint.

Test your home drinking water. You can buy lead testing kits to do it yourself. The EPA recommends to buy lead testing kits to collect samples and then send the samples to a certified laboratory for analysis.

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