CU study: Lead levels even well below U.S. standard may affect brain function in children. Chronicle on line, Nov.20, 2007. Even very small amounts of lead in children’s blood — amounts well below the current federal standard — are associated with reduced IQ scores, finds a new, six-year Cornell study.The study examined the effect of lead exposure on cognitive function in children whose blood-lead levels (BLLs) were below the Centers for Disease Control and Prevention (CDC) standard of 10 micrograms per deciliter (mcg/dl) — about 100 parts per billion. The researchers compared children whose BLLs were between 0 and 5 mcg/dl with children in the 5-10 mcg/dl range.[ See ]