By Helen Albert, Senior medwireNews Reporter
Research suggests that air pollution from lead-contaminated soil may explain the seasonal variation in blood lead levels observed in children, particularly those living in urban areas.
The researchers, led by Shawn McElmurry (Wayne State University, Detroit, Michigan, USA), found that increases in the level of atmospheric lead affected younger children more than older children and boys more than girls older than 1 year.
"Our findings suggest that the federal government's continued emphasis on lead-based paint may be out-of-step (logically) with the evidence presented and an improvement in child health is likely achievable by focusing on the resuspension of soil lead as a source of exposure," write McElmurry and team in Environmental Science and Technology.
"Given that current education has been found to be ineffective in reducing children's exposure to lead, we recommend that attention be focused on primary prevention of lead-contaminated soils."
The researchers assessed atmospheric levels of soil and lead aerosols and tested blood lead levels between 2001 and 2009 in 367,839 children aged 0-10 years living in the Detroit area of Michigan.
Compared with levels in January, mean atmospheric lead levels were 35.7% higher in July, 44.8% higher in August, and 40.0% higher in September. These increases corresponded with a rise in air soil levels in the same months. McElmurry and co-workers calculated that a 1% increase in resuspended soil resulted in a 0.39% increase in the amount of lead in the atmosphere.
Notably, the seasonal variations in atmospheric lead were directly correlated with seasonal variations in blood lead levels in the children tested.
The team also found that increases in the level of atmospheric lead predict greater mean blood lead levels in younger compared with older children. For example, an atmospheric increase of 0.0069 µg/m3 increases blood lead concentrations in children younger than 1 year by 10%, but three times this level of atmospheric lead (0.023 µg/m3) is needed for the same increase in blood lead levels to occur in 7-year-old children.
After the age of 1 year, boys are more affected by exposure to atmospheric lead than girls. Furthermore, the gender difference increases with age, such that boys have a 1.5% higher blood lead level than girls living in the same area at the age of 1 year, and this increases to an 11.2% difference at the age of 7 years.
"Taken together, these facts are suggestive of a [soil to air dust to child] pathway of contemporary lead exposure, where lead-contaminated urban soils are resuspended as dust subject to seasonal precipitation regimes, wind, humidity, and other meteorological factors, with air lead dust inhaled and ingested by unsuspecting children," conclude the authors.
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