The hidden toxic threat in America’s backyards

As the issue recedes from public consciousness, lead exposure is still harming children in complex ways. ThinkProgress takes an in depth look at the toll on one community.

Childhood lead poisoning dramatically decreased across America as the federal government began phasing out leaded gasoline in the 1970s. But many children are still being exposed today because of lead’s legacy: polluted environments, particularly in urban areas.


Now we know that even low concentrations of lead in children are dangerous to their health and well-being. Yet federal, state and local policies have failed to keep up with scientific research and do not protect children from lead’s irreversible consequences.

The U.S. Environmental Protection Agency’s definition of a lead soil hazard in areas where children play is 400 parts per million (ppm) of lead or greater. This is the same standard set by California regulations and adhered to by the state’s Department of Public Health when responding to childhood lead poisoning cases.

Experts say these standards aren’t stringent enough to protect children from being led-burdened. The federal and California soil lead standard of 400 ppm has no margin of safety for children, say the leading experts on childhood lead poisoning. The California Office of Environmental Health Hazard Assessment has deemed that level too dangerous for children and lowered its soil standard to 80 ppm in 2009, but this is not a state regulation.

ThinkProgress tested more than 1,000 soil samples in homes and public spaces throughout Santa Ana, Ca. Nearly a quarter of the samples surpassed the hazardous level of 80 ppm set by the Office of Environmental Health Hazard Assessment.

In 2012, the U.S. Centers for Disease Control and Prevention (CDC) announced that no level of lead in children is safe. The number of Santa Ana children tested with dangerous levels of lead in their blood exceeds the state average by 64 percent. This number includes only those with levels higher than 4.5 micrograms per deciliter (mcg/dL).


There are a far greater number of Santa Ana children who have tested with levels below 4.5 mcg/dL, but most laboratories that test children’s blood lead levels don’t measure below 3 mcg/dL, making it impossible to track precise levels for children in this lower range.

Even if these children were properly identified, they wouldn’t qualify for public health intervention services such as a home visit, an environmental investigation, and case monitoring because they don’t qualify as lead poisoning cases under California Department of Public Health guidelines.

Research shows that children who have blood lead levels below 5 mcg/dL can experience serious consequences such as cognitive deficits, behavioral issues, and educational delays, but those children often don’t show acute physical symptoms of lead poisoning. Studies have also found that children with low to moderate blood lead levels experience the most IQ point loss.

A recent Public Health Institute study found that California and many other states across the country are severely undercounting and underreporting the number of lead-burdened children. African American and Latino children are especially impacted by lead exposure.

The Orange County Health Care Agency has not used state blood lead level data from previous years to geographically map hot spots for lead exposure in Santa Ana or the county, making it challenging to prevent lead poisoning in children.

Research has shown that leaded gasoline particles deposited in California’s South Coast Air Basin, continue to pollute the air due to the resuspension of these particles into the air.


A little known federal regulation allows unleaded gasoline to contain trace amounts of lead, which experts say contributes to already contaminated soil, and harms children, particularly those living in traffic-congested urban areas.

Studies by epidemiologists, criminologists, and economists have shown that the reduction in leaded gasoline emissions that began in the 1970s is a factor in the drop in violent crime across the United States, and that childhood lead exposure is a factor in criminal behavior later in life.

Explore the compete soil test results.