Changes in Soil Lead Levels Indicate Lead Exposure Risks for Children
Sat, April 10, 2021

Changes in Soil Lead Levels Indicate Lead Exposure Risks for Children

Lead exposure may affect your health and development, especially to children / Photo Credit: Shutterstock


A new study from Tulane University in New Orleans could serve as a model for cities worldwide in tracking lead levels on soil, which researchers said is critical for municipalities in identifying the risks of lead contamination in children. Published in the Proceedings of the National Academy of Sciences, the work is the first to present how long-term changes in the lead levels are relative to the lead blood levels in children.

Lead exposure, especially for children, is often irreversible and results in adverse health effects that affect the development of their brain and nervous system. "Lead dust is invisible and it's tragic that lead-contaminated outdoor areas are unwittingly provided for children as places to play," said Howard Mielke, lead author and a pharmacology research professor at Tulane University School of Medicine. "Young children are extremely vulnerable to lead poisoning because of their normal crawling, hand-to-mouth, exploratory behavior."

Soil samples and blood data

In 2001, the researchers collected about 5,500 samples in the neighborhood, busy streets, near residences, and open spaces such as parks to track the amount of lead in New Orleans soil. They did the same procedure of gathering soil samples 16 years later.

The second batch of samples showed a 44 percent decrease in the amount of soil lead both in communities devastated by Hurricane Katrina in 2005 and those saved from the levee failures and storm surge, a press release stated.

Using data maintained by the Louisiana Healthy Homes and Childhood Lead Poisoning Prevention Program from 2000-2005 and 2011-2016, the researchers compared the soil lead with children's blood lead levels. They found that for blood lead, levels dropped by 64 percent in the 2011-2016 period from 2000-2005.



The press release added that a "decreasing lead in topsoil played a key factor in the declining children's blood lead levels."

Even with the significant improvement in lead levels in soil, the researchers said current topsoil data also indicates that many communities within the city are still too contaminated to "appropriately support children’s health and welfare trajectory into adulthood.

"Along with other measures for reducing exposure and upholding the principles of environmental justice, primary prevention requires interventions that decrease [soil lead] in excessively contaminated communities," the researchers explained.

An environmental issue

The researchers considered lead exposure as a "critical environmental justice issue," especially with results showing black children are three times more likely to have higher blood lead levels compared to white children. This could be explained by the children's socioeconomic status and education, the type, and age of housing. and proximity to major roads and industry.

Children living in New Orleans communities that have more lead in the soil and higher blood lead levels exhibit poorer school performance. The metal has recently been cited as a major risk factor for premature death in the US, especially from cardiovascular disease, and accounts for 412,000 premature deaths a year.


The lead exposure is also seen as a critical environmental issue / Photo Credit: Shutterstock


"While the metabolism of the city could theoretically affect all residents equally, in reality, social formations produce inequitable outcomes in which vulnerable populations tend to bear greater burdens of contaminant exposure," said Mielke.

He added that more research is needed to determine if the changes in the New Orleans demographic since 2001 accounted for the decline in children's blood lead levels and if the decreases are occurring equitably for all populations.

The burden of lead exposure

Lead is one of the most used and toxic metals found in nearly everything, from toys to paint and even traditional medicine. Drinking water may also contain lead if it passes through lead pipes or pipes joined with lead solder.

Everyone is exposed to the dangers of lead and children are particularly vulnerable to its toxic effects. Lead exposure puts children at risk of behavioral or learning problems, lower IQ, delayed growth, and sometimes seizures, coma, or death.

Data from the Institute for Health Metrics and Evaluation (IHME) in 2017 showed that lead exposure accounted for 1.06 million deaths worldwide while long-term effects resulted in 24.4 million deaths, according to the WHO.



It added that exposure attributed to 63.2 percent of the global burden of idiopathic developmental intellectual disability, 10.3 percent of the global burden of hypertensive heart disease, 5.6 percent of the global burden of ischemic heart disease, and 6.2 percent of the global burden of stroke.

Reducing lead exposure included phasing out leaded gasoline and lead paint. Most countries have successfully phased out leaded gasoline while 37 percent have introduced legally binding controls on lead paint. This, along with other lead control measures, led to a notable decline in population-level blood lead concentrations.

Eliminating lead paint will help in reducing the number of deaths and illnesses due to hazardous chemicals as well as air, water, and soil pollution and contamination. It will also help achieve the environmentally sound management of chemicals and all wastes through their life cycle to minimize their adverse impacts on human health and the environment.