A new study at the University of California, Berkeley has found that the risk of toxic effects of pesticides on kids extends much longer into childhood than previously expected.
Newborns' levels of an enzyme called paraoxonase 1 (PON1), critical to the detoxification of organophosphate pesticides, average one-third or less than those of the babies' mothers.
It was earlier believed that PON1 enzyme activity in children approaches adult levels by age 2.
But the researchers have now found that the enzyme level remains low in some individuals through age 7.
On the basis of their findings, the researchers have recommended that the U.S. Environmental Protection Agency (EPA) re-evaluate the current standards for acceptable levels of pesticide exposure.
"Current EPA standards of exposure for some pesticides assume children are 3 to 5 times more susceptible than adults, and for other pesticides the standards assume no difference," said Nina Holland, UC Berkeley adjunct professor of environmental health sciences and senior author of the paper.
She added: "Our study is the first to show quantitatively that young children may be more susceptible to certain organophosphate pesticides up to age 7. Our results suggest that the EPA standards need to be re-examined to determine if they are adequately protecting the most vulnerable members of the population."
The study involved 458 children from an agricultural region who were followed from birth through age 7.
Cord blood samples were collected from all children to determine their PON1 genotype and to obtain baseline measures of the enzyme's activity level.
The researchers observed that on an average the quantity of enzyme quadrupled between birth and age 7.
The study has been published in the journal Environmental Health Perspectives.