Children with even slightly higher blood lead levels than normal are less likely to be ready for reading in kindergarten, according to a new study published in Pediatrics.

Although other studies have shown that lead affects children's performance in school, the new study is significant because it is "looking at even fairly low levels of lead exposure and still finding significant impacts on kindergarten reading readiness," said Marie Lynn Miranda, professor at Michigan State University, who was not part of the research.

The threshold for blood lead level at which parents and physicians should take action was lowered in 2012 by the Centers for Disease Control and Prevention (CDC), from 10 micrograms of lead per deciliter to five micrograms, reports Reuters Health.

But the new study found that even lead levels below the CDC threshold can affect childhood literacy.

In the United States, one child in 40 has lead levels higher than five micrograms per deciliter, according to Mary Jean Brown, chief of CDC's Lead Poisoning Prevention Branch.

The authors of the study called for greater efforts toward preventing children from being exposed to lead at an early age. Such preventative efforts might improve reading readiness for children entering kindergarten.

"Reading readiness at the beginning of kindergarten indicates that children are or are not ready to pursue schoolwork," said Pat McLaine, the lead author of the study at the University of Maryland School of Nursing. "And if they're not ready, there's a lot of remedial work that goes on that the school district then has to take care of."

The study found that one of three children failed the reading readiness benchmark, meaning they fell short of certain standards like knowing their letters well.

The study drew on the experience of 3,406 children who started kindergarten between 2004 and 2006, using data from a Providence, Rhode Island Public School District partnership with the Rhode Island Department of Health.

The study found that kids with high blood lead levels were less likely to meet kindergarten literacy benchmarks.

For 217 children with blood lead levels over 10 micrograms per deciliter, 49 percent met literacy benchmarks. For the 1,098 children with levels between five and nine micrograms per deciliter, 62 percent met benchmarks. For the 2,091 kids with levels below five, 68 percent passed.

As compared with children with blood lead levels below two micrograms per deciliter, literacy rates declined as blood lead levels rose.

Children with blood lead levels as low as three micrograms per deciliter scored 3.3 points lower on the 102-point literacy test than children with blood lead levels below two.

Both of those scores are lower than the threshold for taking action, as currently recommended by the CDC.

"I would say that if parents have children with a blood lead level below five, they should not assume that everything is fine," Miranda told Reuters Health.

Miranda recommended two approaches for lowering average blood lead levels. One approach is for the CDC to lower its threshold. The second approach is to make pediatricians and families more aware of the dangers of lead, so they can take preventative measures.

Speaking for the CDC, Brown declined to comment on the study, but stated that "because we can't find a safe blood lead level means we have to do primary prevention, which means controlling or eliminating levels before they have a high blood level."

Researchers recommended additional studies of blood lead levels in high-risk populations.

Although lead was removed from paint in 1978, children may still be exposed to it in older homes.

To prevent your child from being exposed to lead, ensure that he or she does not eat peeling paint chips. Keep your children out of older homes undergoing renovations.


Pat McLaine, et al. Elevated Blood Lead Levels and Reading Readiness at the Start of Kindergarten. Pediatrics. 2013.