Even children with low levels of lead in their blood score lower on
reading-readiness tests when they begin kindergarten, a new study found.
"We now know that poorer scores on reading-readiness tests are associated
with low lead levels," said researcher Patricia McLaine, director of
community/public health nursing at the University of Maryland School of Nursing.
"That's important, because we are very concerned about children having
sufficient reading readiness when they enter kindergarten.
"For success at school, it's another indication that we need to identify
children who are being exposed to lead and take action to protect them and
reduce their exposure," she added.
No safe levels
McLaine said she believes there is no safe level of lead exposure for
children. Last year, the US Centers for Disease Control and Prevention lowered
the blood lead level that would be considered concerning from 10 micrograms per
decilitre (mcg/dl) to 5 mcg/dl. That means many more children under the age of 5
can now be diagnosed with too much lead in their blood, a condition that has
been linked to developmental problems and even a lower IQ, according to the
But one expert said that is not enough, particularly given the latest
"This confirms that there is really no safe level of lead," said Ruth Ann
Norton, executive director of the Green & Healthy Homes Initiative.
"The CDC should eliminate the term 'level of concern,' and say any level is
of concern," she said.
"Clearly, zero has to be the goal," Norton said. "We have set a false
guidance. We have failed more generations of kids by not aggressively moving to
zero tolerance of lead poisoning."
Another expert echoed that concern.
"The idea that there is a correlation between low lead levels and reading
readiness and school performance is very concerning," said Dr Jefry Biehler, a
paediatrician at Miami Children's Hospital.
"This study brings into question what are acceptable lead levels and what
lead levels actually result in developmental changes in performance in school,"
Biehler said. "It has always been my fear of how much lead is too much and how
much is OK."
What the study found
For the study, McLaine's team collected data on reading-readiness scores on
more than 3 400 kindergarten children in Providence, R.I, and compared them with
levels of lead in the children's blood.
They found that children with lead levels between 5 mcg/dl and 9 mcg/dl were
21% more likely to score below the national benchmark on the reading-readiness
test. Children whose lead levels were 10 mcg/dl were 56% more likely to score
below the national benchmark.
Moreover, reading-readiness scores dropped four and a half points for
children whose lead levels were 5 mcg/dl to 9 mcg/dl and dropped 10 points for
those with lead levels of 10 mcg/dl, compared with children whose blood lead
levels were 0.5 mcg/dl, the researchers said.
McLaine noted, however, that there is no safe level of lead exposure. "We
found effects when blood levels were above 2 [mcg/dl]," she said.
This is another reason to prevent lead poisoning altogether, McLaine
According to the CDC, children in at least 4 million homes in the United
States are being exposed to lead. Approximately half a million US children
between the ages of 1 and 5 have blood lead levels above 5 mcg/dl.
Most of the exposure comes from old, chipping lead-based paint, which was
banned in 1978 but is still found in public housing in urban areas and in many
For more information on lead, visit the US Centers for Disease Control