Can some of the detrimental neurodevelopmental effects attributed to lead be due to pesticides?

[Guest guest]

Can some of the detrimental neurodevelopmental effects attributed to

lead be due to pesticides?

/Science of The Total Environment//*

In Press, Corrected Proof*//

Available online 20 February 2008/

L. Gulson

Abstract

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PDF (180 K)

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<http://www.abc.net.au/reslib/200803/r229674_915813.jpg>

foto: Scientists didn't ask about household pesticide exposure in past

studies looking for what's behind low child IQ, says one researcher. So,

could they play a larger role in neurodevelopmental delay than we think?

/(Source: iStockphoto)/

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Pesticides may be hidden danger to child IQ

Wednesday, 5 March 2008

Dani

ABC

http://www.abc.net.au/science/articles/2008/03/05/2178230.htm

Household pesticides may cause some of the intellectual development

problems in children previously associated with lead, an Australian

toxicologist says.

In a commentary available online in the journal Science of the Total

Environment, Professor Gulson says there is no question lead has a

detrimental effect on children's intellectual development.

But the Macquarie University researcher says several studies have shown

similar effects in children exposed to low levels of organophosphate

pesticides.

He says the similarity in effects and the overlap in timing of the major

use of these pesticides in the community and lead exposure studies could

have resulted in confusion.

But his comments have been dismissed as an " interesting idea " that is

" not well supported " by the science.

They come as regulatory bodies in the US, Canada and Australia are

reviewing guidelines for acceptable levels of lead in the blood.

Gulson, who is contributing to Australia's National Health and Medical

Research Council review, says the US is pushing for to half the current

blood lead level of 10 micrograms per decilitre.

He is against the move to 5 micrograms per decilitre saying the

technology is not yet available to determine lead's impact on IQ, or

intellectual quotient, at that level.

Also he suggests not all the neurodevelopmental effects can be blamed on

lead.

" 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, " he writes.

Pesticide use in pregnancy

He points to a 2002 study of female ethnic minorities living in New York

City in which 85% said pest control measures were used in their home

while they were pregnant.

He says the organophosphate insecticide chlorpyrifos was banned for

residential use in the US in 2002.

Yet in a 2007 paper, researchers said they detected residue of the

insecticide in all participating New York City homes more than 2 years

after the ban.

Gulson says because researchers tracking lead exposure have never asked

about pesticides, his concern about their role in damaging intellectual

development cannot be dismissed.

He says future lead studies need to 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, " he writes.

Where's the evidence?

Toxicologist Professor Winder, at the University of New South

Wales, says while Gulson's view is an " interesting idea " he does not

support it.

" While some pesticides may affect neurological development, most

typically the organophosphates, many household pesticides do not contain

them, " says Winder, from the School of Safety Science.

" However, lead is a known neurotoxicant, and its effects on reproduction

and neurodevelopment are extensive and very well known. "

Dr Helen Ritchie, of the University of Sydney's School of Medical

Sciences, says the fact there may be co-exposure to lead is plausible.

" But without data on dose or exposure then nothing really can be said, "

says Ritchie, who specialises in the chemical causes of birth defects.

" You could equally ask whether the detrimental neurobehavioural effects

attributed to lead could be due to any other chemical you might think of. "

*

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