Lead exposure in childhood may lower IQ later in life: study

Childhood exposure to powerful neurotoxins such as lead may adversely affect brain health and result in lower IQs later in life, a new study has warned.
Researchers from Duke University in the US studied about 1,037 participants, of whom 565 (56 per cent) had been lead tested at age 11 and grew up with exposure to high gasoline lead levels.
They found that childhood blood lead level was linked to lower adult IQ scores nearly three decades later, reflecting cognitive decline following childhood lead exposure.
Childhood blood lead level was associated with lower adult socioeconomic status, reflecting downward social mobility following childhood lead exposure.

They found that participants who were found to carry more than 10 microgrammes of lead per deciliter of blood at age 11 had IQs at age 38 that were on average 4.25 points lower than their less lead-exposed peers.
They were also found to have lost IQ points relative to their own childhood scores.

Researchers also found that for each 5-microgramme increase in blood lead, a person lost about 1.5 IQ points.
The effects are slight, but significant, showing that the higher the blood lead level in childhood, the greater the loss of IQ points and occupational status in adulthood, researchers said.

"The results indicate that childhood exposures to lead can be linked with cognitive and socioeconomic outcomes detectable more than 3 decades later," said Aaron Reuben of Duke University.
The study was published in the Journal of the American Medical Association.