behavior , and also took urine and dust samples .
a disturbing new study has linked a common chemical found in head lice treatments to behavioral difficulties in children .
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( permethrin , an active ingredient in the most popular drugstore lice treatments , is a pyrethroid . )
as a result , the researchers concluded that pyrethroids might alter neurochemical signaling in the brain .
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the research , which was published in the journal occupational & environmental medicine , found that children who had higher levels of certain pyrethroids — which are synthetic chemicals used in insecticides like head lice treatments and some mosquito repellents — in their system were more likely to display abnormal behaviors at age 6 than those who did n’t .
for the study , the researchers measured levels of five pyrethroid metabolites in the urine of women in the early stages of pregnancy and , later , in their 6 - year - olds to see if there was a link between being exposed to the chemical in utero and childhood , and behavior that could suggest neurodevelopmental damage .
overall , children with the highest levels of metabolites in their urine were three times more likely to have abnormal behavior than those with lower levels .