A pesticide found in common household products has been found to triple a boy’s risk of being diagnosed with attention deficit hyperactivity disorder, scientists have warned.
Symptoms of the condition, notably hyperactivity and impulsivity, were found to be associated with exposure to pyrethroid pesticides, the US researchers found.
The ingredient is found in many common insecticides and some insect repellents.
Experts, led by those at Cincinnati Children’s Hospital Medical Center, noted the link was stronger in boys than in girls.
Paediatrician Tanya Froehlich, the study’s author, said: ‘Given the growing use of pyrethroid pesticides and the perception that they may represent a safe alternative, our findings may be of considerable public health importance.
In the US officials banned the two most commonly used organophosphate pesticides – containing organic compounds with phosphorus – from residential use in 2000, after concerns were raised over adverse health consequences.
The ban led to the increased use of pyrethroid pesticides, which are now the most commonly used pesticides for residential pest control and public health purposes in the US.
They are also increasingly used in agriculture.
Pyrethroids have often been considered a safer choice because they are not as acutely toxic as the banned organophosphates.
Pyrethroid pesticide is found in pest control sprays
But the researchers note, animal studies have suggested a heightened risk of hyperactivity, impulsivity and abnormalities in the dopamine system in male mice.
Dopamine is a neurochemical in the brain thought to be involved in many activities, including those that govern ADHD.
Researchers studied data from 687 children between the ages of eight and 15, from the National Health and Nutrition Examination Survey in 2000 to 2001.
Pesticide exposure measurements were collected in a random sample of the urine of half the eight to 11-year-olds, and a third of the 12 to 15-year-olds.
Boys with a detectable measure, known as 3-PBA, of pyrethroids in their urine, were three times as likely to be diagnosed with ADHD, compared with those who had no detectable trace of the pesticide.
Hyperactivity and impulsivity increased by 50 per cent for every 10-fold increase in 3-PBA levels in boys.
The biomarkers were not associated with increased odds of ADHD diagnosis or symptoms in girls.
Dr Froehlich, added: ‘Our study assessed pyrethroid exposure using 3-PBA concentrations in a single urine sample.
‘Given that pyrethroids are non-persistent and rapidly metabolised, measurements over time would provide a more accurate assessment of typical exposure and are recommended in future studies before we can say definitively whether our results have public health ramifications.’
The study was published in the journal Environmental Health.