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 Researchers tested lead levels in the soil, sand, mulch or rubber
surface materials in 28 playgrounds and found the rubber surfaces
often averaged two or three times the lead levels of the other
materials. Many of the highest lead levels were also found in soil
surfaces, making sand and mulch the healthier surface choices for
playgrounds, the study team writes in PLoS ONE.
"Playgrounds use a variety of materials to protect children against
injuries. However, we should always consider the full suite of
health effects associated with materials that children come into
contact with," said study author Nick Arisco of the Harvard T.H.
Chan School of Public Health in Boston.
Most research on lead exposures in children's outdoor play areas has
focused on soil contamination. Rubber surfaces have been used more
in recent years for injury prevention and to recycle waste tires, he
said.
"Understanding the benefits and risks of using different materials
can help inform healthier playground design moving forward," he told
Reuters Health by email.
Arisco and colleagues examined lead levels in poured-in-place rubber
and compared them to levels in soil, sand and wood mulch materials
from randomly selected playgrounds in neighborhoods representing
every socioeconomic category in the city. They chose Boston in part
because from 2009 to 2013, the lower-income neighborhoods of East
Boston, North Dorchester, Roxbury and Mission Hill contributed a
disproportionate number of the entire city's cases of elevated blood
lead levels in children.
In the study, each playground tested had at least two types of
surface material, so a total of 85 samples were included in the
analysis. Overall, the testing found that average lead levels in
soil surfaces were 66 micrograms, or parts per million, per gram of
soil. For rubber surfaces, the average was 22 micrograms per gram,
and mulch averaged 9 micrograms per gram with sand averaging 8.5
micrograms per gram.
For rubber and soil, however, there were wide ranges of readings.
One soil sample exceeded the 400-microgram limit set by the
Environmental Protection Agency for play areas, the study team
notes. In addition, nine playgrounds had a soil sample greater than
80 micrograms.
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Two playgrounds had a rubber sample with greater than 80 micrograms
of lead per gram, which exceeds the 80-microgram limit set as a
residential soil guideline in California. Public health experts
prefer to use the California limit, especially for play areas where
children as young as 6 months old play.
"One reason children are especially vulnerable to exposures to lead
and other chemicals is because they spend a lot of time on the
ground, touching things and then putting their hands to their
mouth," Arisco said.
Parents can encourage children to wash their hands after playing on
playgrounds and remove their shoes at the door to prevent
contaminated soil from tracking inside. For outdoor play areas at
home, parents can cover the soil with a top layer of clean sand or
mulch, he added.
In addition, the Centers for Disease Control and Prevention created
an online guide to preventing lead poisoning (available here:
https://bit.ly/2znTv0Q ) that also answers frequently asked
questions. No safe blood lead level in children has been identified,
and even low levels can affect attention and academic achievement,
according to the CDC.
"Unfortunately, urban soils are often invisibly and severely
contaminated with lead dust generated from multiple sources," said
Howard Mielke, an environmental health researcher at Tulane
University School of Medicine in New Orleans, Louisiana.
Mielke, who wasn't involved with the research, noted that one option
to reduce lead exposure used by some childcare centers he has
studied was to import low-lead soil from outside of the city to put
in play areas.
"The public needs to be aware that urban soils became invisibly
lead-contaminated (in past decades) as a result of industrial
activities," he said by email. "Fortunately, the amount of lead in
soil is decreasing since lead was banned in gasoline."
SOURCE: https://bit.ly/2Wtzbq7 PLoS ONE, online April 25, 2019.
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