Winnipeg Free Press - PRINT EDITION

The evidence for a pesticide ban

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In his article, Baseless pesticide claptrap (April 19), Ken Wiebe asserts scientific studies on pesticides and adverse effects on health, used to support the Province of Manitoba's planned phase-out of cosmetic pesticides through legislation, are "twisted." So, who are some of these "activists" that are mentioned in that article and on what basis are they making "deceiving" statements?

One of the main groups leading the campaign for pesticide reduction is the Canadian Association of Physicians for the Environment composed mostly of physicians. Children's environmental health is their priority issue. The Ontario College of Family Physicians report of 142 peer-reviewed studies on pesticides and health found adverse effects to reproductive health, neuro-developmental behaviour in children and respiratory health in children and adults. These medical scientists from respected Canadian hospitals and universities had no conflicts of interest.

Dr. Vandenberg and colleagues at Tufts University concluded the effects of low doses cannot always be predicted by effects at high doses. "The dose makes the poison" does not always apply because hormones work at extremely low concentrations, and when hormone function is affected there can be "large effects from small exposures." A properly functioning hormone system is critical for good health.

The Ontario college advice to family physicians includes: "... to counsel to reduce pesticide exposure and help reduce negative birth outcomes, neuro-development problems and childhood asthma outcomes associated with prenatal pesticide exposure" and to "advise parents to minimize exposure of older children by reducing use of indoor and home garden pesticides."

The American College of Obstetricians and Gynecologists and the American Society of Reproductive Medicine have made clear statements that pregnant women should minimize their environmental exposure to chemicals that may cause miscarriages, stillbirth and preterm birth. They also state that "... pesticide exposure in men is associated with poor semen, sterility and prostate cancer" and "... exposure to pesticides may interfere with puberty, menstruation and ovulation, fertility and menopause in women."

Pesticide registration hinges upon confidential industry-supplied animal studies, while the doctors rely upon public, peer-reviewed human studies. Add to this that the traditional dose-response assumptions cannot be relied upon, and we have reason to look beyond current approvals and call for updated evaluation methods.

How can the safety of Canadian children be guaranteed if Health Canada's Pesticide Management Regulatory Agency (PMRA) evaluation process is incomplete, inadequate and needs updating? To truly evaluate how Health Canada has arrived at their conclusions for the lack of "danger" of some pesticides, they need to open up their review process to the public and reveal how different studies were "weighed" for evidence and credibility. Specifically for 2,4-D, a paper in the journal of the Canadian Paediatric Society, Paediatrics and Child Health, states " ... (the Health Canada) assessment of this pesticide does not approach standards for ethics, rigour or transparency".

Past experience with fetal alcohol syndrome and thalidomide have taught us exposure to toxins during vulnerable periods of fetal development can have serious lifetime consequences. Science, experience and common sense support minimizing use of pesticides in our environment -- a simple, preventative measure. Would anybody want lifetime impairment of a child on their conscience for the sake of a few dandelions?

Manitobans who care about children should go beyond supporting this legislation. We should be insisting on it.


Marg Friesen, of the volunteer-based and not-for-profit Environmental Health Association of Manitoba, studied effects of a pesticide on non-target species for her MSc thesis.

Republished from the Winnipeg Free Press print edition April 22, 2014 A7

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