A recent study discovered that around 25% of U.S. households have soil that surpasses the new lead screening levels set by the U.S. Environmental Protection Agency. The new levels are now at 200 parts per million (ppm), which is half of the previous level of 400 ppm. The study also revealed that for households with exposure from multiple sources, the EPA has lowered the guidance to 100 ppm, and almost 40% of households exceed that level.The Environmental Protection Agency (EPA) has reduced its guidance on lead exposure to 100 ppm due to the high levels found in nearly 40% of households, according to a new study. The lead researcher, biochemist Gabriel Filippelli from Indiana University, expressed surprise at the number of households exceeding the new 200 ppm guideline. He also noted that the situation is even worse for the 100 ppm guideline. The study estimated that traditional soil removal methods for the roughly 29 million affected households could cost over $1 trillion. The study was published in GeoHealth.h, an open-access AGU journal that publishes research investigating the intersection of human and planetary health for a sustainable future. Filippelli is the former editor-in-chief of GeoHealth.
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Lead is a heavy metal that can build up in the human body and have harmful effects. In children, being exposed to lead is linked to lower educational achievement. In the United States, lower-income communities and communities of color have historically suffered the most from lead exposure due to redlining and other discriminatory practices. Lead pollution can come from various sources, including old lead-based paint, contaminated soil, and water.Old paint, aging water pipes, and remnants of gasoline and industrial pollution used to be the primary sources of lead exposure. However, nowadays, the majority of lead exposure comes from contaminated soil and dust, even after lead-containing infrastructure has been removed.
In 1991, the Centers for Disease Control and Prevention initially set a limit on the concentration of lead in blood at 10 micrograms per deciliter. This limit was then lowered several times, eventually reaching the current limit of 3.5 micrograms per deciliter. The EPA’s soil lead screening level had remained unchanged for over 30 years until the announcement in January. Some states had already established their own lower guidelines; for example, California has its own.
The delay in addressing this issue is likely due to the immense and widespread nature of the problem, as stated by the study authors. The enormity of the problem is astonishing, and efforts to address lead contamination and remediation have become significantly more complex. This is because when the EPA lowers a screening limit, they must provide guidance on what to do if the soil exceeds it.
After the EPA lowered the screening level, Filippelli and his co-authors utilized a database containing 15,595 residential soil samples from across the United States to determine how many of them exceeded this new limit.The study found that approximately 25% of soil samples from residential areas exceeded the new 200 ppm level, while only 12% had exceeded the older 400 ppm level. This equates to roughly 29 million households across the country. The EPA has issued separate guidance for households with multiple sources of lead exposure, setting the level at 100 ppm in those situations. It is estimated that this applies to about 40% of urban households.The study found that the number of affected households is nearly 50 million, as more households exceed the contamination limit. Typically, contaminated soils are cleaned up through the costly process of “dig and dump,” which is only used after an area is put on the National Priority List for remediation. This can take years to complete. The authors of the study calculated that the cost of remediating all contaminated households with “dig and dump” would range from $290 billion to $1.2 trillion. A more affordable alternative is “capping,” which involves burying the contaminated soil with about a foot of soil or mulch. Another method is to use a geotechnical fabric barrier to contain the contamination.Installed. According to Filippelli, most lead contamination is concentrated in the top 10 to 12 inches of soil, so this straightforward approach either addresses the issue or reduces it to a safe level.
“Urban gardeners have been utilizing this method for a long time, especially with raised beds, because they are naturally concerned about the previous land use on their property,” Filippelli explained.
In addition, capping is a faster solution.
“One major benefit of capping is its efficiency. It immediately decreases exposure,” Filippelli explained. “You don’t have to wait for two years for your yard to be cleaned up while your child is at risk of lead poisoning. It can be completed in just one weekend.”
Even though capping takes time and effort, residents need to locate clean soil, bring it to their homes, and spread it out. However, the health benefits are likely worth the effort, according to Filippelli.
As capping has been done in a more informal manner, there is still much to be learned about its longevity and sustainability, Filippelli noted. This will be the focus of future research.
Despite the massive scale of the problem, Filippelli remains optimistic. He stated, “Lead is the most easily solvable problem that we have. We know where it is, and we know how to avoid it. It’s just a matter of taking action.”
