Lead has been shown to affect school performance, but what's important in this study is "looking at even fairly low levels of lead exposure and still finding significant impacts on kindergarten reading readiness," said Marie Lynn Miranda, a professor at Michigan State University, who was not part of the research.
The Centers for Disease Control and Prevention (CDC) in 2012 lowered the blood lead level threshold at which doctors and parents should take action from 10 micrograms of lead per deciliter to five micrograms (see Reuters report of May 17, 2012 here: http://reut.rs/JPN9rH).
About one in 40 kids in the U.S. has levels above five micrograms per deciliter, according to Mary Jean Brown, chief of CDC's Lead Poisoning Prevention Branch.
The new findings are "important because 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 researchers used data from a Providence, Rhode Island Public School District partnership with the Rhode Island Department of Health that included 3,406 children who started kindergarten between 2004 and 2006.
About one out of three of the kids failed the reading readiness benchmarks. This means they didn't meet goals such as knowing their letters well.
McLaine and her colleagues found that kids with higher blood lead levels were less likely to have met the reading readiness goals.
Among the 217 children with levels over 10 micrograms per deciliter, 49 percent met the literacy benchmarks.
In comparison, 62 percent of the 1,098 kids with levels between five and nine, and 68 percent of the 2,091 kids with levels below five met the benchmarks.
In addition, the researchers report in the journal Pediatrics that compared to kids with levels below two, children's literacy scores progressively dropped as blood lead levels got higher.
For instance, children with a blood lead level of three micrograms per deciliter scored 3.3 points lower on the literacy test than children with levels below two, and kids with a level of eight micrograms per deciliter scored 9.3 points lower on the 102-point test.
"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.
One way to approach the problem could be to have CDC lower its threshold for action even more, said Miranda, but it could also be through pediatricians and families being aware of the hazards of lead and taking steps to fix it before it becomes a problem.
The CDC's Brown would not comment on the study, but said, "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."
Lead was removed from paint in 1978, but children may be exposed to it in older homes. The CDC recommends that adults make sure kids don't eat peeling paint chips and keep them out of older homes undergoing renovation.
SOURCE: http://bit.ly/12xpF2M Pediatrics, online May 13, 2013.