Washington, Mar 5 : An Australian toxicologist has pointed out that some of the intellectual development problems in children earlier linked to lead, could also be caused by household pesticides.
Professor Brian Gulson at Macquarie University, however on one hand agrees that lead is harmful for children's intellectual development, but at the same time he supports many studies showing that low level exposure to organophosphate pesticides may be equally detrimental to children's IQ.
He also stated that the confusion in the effects of lead and pesticides must have resulted because of the similarity in effects and the overlap in timing of the major use of these pesticides in the community and lead exposure studies. But other scientists have dismissed his comments as an "interesting idea" that is "not well supported" by the science.
Gulson's comments come in line with the review of guidelines for acceptable levels of lead in the blood by the regulatory bodies in the US, Canada and Australia. He said that the US is under pressure to halve the current blood lead level of 10 micrograms per decilitre.
He disagrees to the shift to 5 micrograms per decilitre saying that they do not have the technology to measure impact on IQ, or intellectual quotient, at that level. Besides, he even suggested that lead couldn't be solely blamed for all the neurodevelopmental effects.
"Many of the lead studies have been undertaken in communities where the subjects may be exposed to rodents and insects [and] the chemicals used to eradicate them," Live Science quoted him, as saying. He even linked pesticide exposure in pregnancy to effects on children's IQ. Pointing to a 2002 study of female ethnic minorities living in New York City in which 85pct agreed to use pest control measures in their home while they were pregnant, he said that the organophosphate insecticide chlorpyrifos was banned for residential use in the US in 2002.
But still, he said that in a 2007 study, it was said that residue of the insecticide in all participating New York City homes was detected more than 2 years after the ban.
He said that as researchers investigating lead exposure have never considered pesticides, one couldn't disregard his concern about their role in damaging intellectual development.
He stressed on the point that future lead studies should include questions about pesticide use in the home, but admits the "horse might have bolted. The current very low blood lead levels compared with the earlier longitudinal studies will limit the possibility to determine respective contributors to neurodevelopmental deficits."
Despite of his strong recommendations, many researchers have opposed his view.
Gulson's commentary is available online in the journal Science of the Total Environment.