During last spring's Parliamentary hearings into the proposed new Pest Control Products Act, many experts testified to the serious and long term health impacts of pesticides, and argued that the final law needed to be stronger and more effective. None of the changes they proposed were incorporated into the new law. The testimony of Dr. Margaret Sanborn, reprinted in part below, looks at the effect of pesticides on neurodevelopment (the brain) and reproduction.
The effect of pesticides on brain formation,
or neurodevelopment, is an area of great concern. Animal studies have shown
that pesticide-exposed rats and mice have fewer brain cells, permanent
changes in the levels of neurotransmitters (messenger chemicals) in the
brain, defective cell-to-cell signaling, and hyperactive behaviour which
persists into adult life. These changes occur at exposure levels which
do not cause acute toxicity. They also occur from pesticides in current
household use, such as chlorpyrifos and pyrethroids - substances previously
thought to be much
It is clear that the brains of children are more susceptible to pesticide effects. For example, in pesticide poisonings, 25% of children present with seizures as a symptom; in adults only 2-3% present with seizures. In children, we are concerned about sharp increases in the rates of autism and attention deficit disorders (previously called hyperactivity). Health Canada has stated recently that 28% of Canadian children under the age of 12 have an identified learning or behaviour problem. Apart from these known clinical disorders, there is a spectrum of less severe problems which involve memory and attention, and affect learning ability and skills to socialize and form relationships. Given the animal data, it is a concern that some of the increase in these problems may be pesticide-related. It is instructive to note that the recent quiet withdrawal of DEET formulations over 30% was done because of neurodevelopmental toxicity.
I would like to draw attention to the dramatic population effects caused by small reductions in brain function. A reduction of only 5 IQ points across the whole population causes a 57% increase in those classified as "mentally challenged", and a corresponding 57% decrease in those classified as "intellectually gifted". The economic and social costs of such a shift, both in increased health and social costs at the lower end, and reduced capacity for innovation and knowledge-based economic output at the upper end, are enormous. I believe these concepts deserve serious consideration when cost-benefit , or "health risk-value" analyses of pesticides are conducted.
Dr. Margaret Sanborn
is a rural family physician, Assistant Clinical Professor of Family Medicine
at McMaster University, and a member of the Ontario College of Family Physicians
Environmental Health Committee.