Stats probed for pesticide
Some health disorders appear to be worse in rural areas where more pesticides are sprayed

By Laura Rance, Special to Ontario Farmer, Tuesday, January 16, 2007

People who live in rural areas where farmers use more pesticides suffer higher rates of certain health disorders, a University of Manitoba researcher has found.

As part of her Masters program thesis in Community Health Sciences Research, Jen Magoon found there is a small but significant increase in perinatal conditions, congenital anomolies and eye disorders among rural residents living in areas where farmers apply more products more often.

"They are not large. They are modest associations, but they were significant," Magoon said in an interview after successfully defending her thesis before a panel of academic supervisors in November.

The project is unique in the both the methodology and the question it explored. Most studies into the health effects of pesticides have focused on the impact on applicators and their families, or consumers of the final product.

This effort attempts to determine the association between higher usage and the general population's healths.

Magoon combined four years of data collected in two diverse databases kept by the Manitoba government to track whether the prevalence of pesticide use is correlated to the population's health.

She used the Manitoba Agricultural Services Corporation's crop insurance database and Manitoba Health's database, which tracks the occurrence of illness in the province by residential postal code.

Whenever a resident is diagnosed with an illness, that diagnosis is categorized and entered into the Population Health Research Data Repository database that tracks illness by where that person lives - not where they seek medical attention.

Farmers annually supply the Manitoba Agricultural Services Corporation with reports of the pesticides, herbicides and insecticides they use on their land. Those records are compiled into a website that allows researchers to track the type and number of products used on farmland, although it does not identify how many times a product is used during the season.

Magoon used the crop insurance data to develop a usage index based on Census Consolidated Subdivisions, a geographical area that includes the populations of rural municipalities with their associated small towns. She excluded population centers of 5,000 people or more.

The regions included in the study contained a sample of 114 CCSs and a population of 323,368 people.

"We looked at what proportion of acres were sprayed annually of any type of pesticide, herbicide, insecticide or fungicides. We added up all those acres and divided it by the total acres," she said. "It's giving you an idea of the density of use."

She also annualized it then averaged the results over four years of use. So if a farmer used a specific product on his or her land once in a year it would be tracked, but not how many times that product was used.

Magoon recognizes the results could actually underestimate the level of pesticide use because the number times a specific product was used are not tracked. "It was the best that we had," she said.

Not surprisingly, the Red River Valley and South Central Manitoba where the bulk of specialty annual crops are produced have the highest densities.

Recognizing that different active ingredients have differing toxicity levels, Magoon consulted with an agronomist to determine average use rates and determine a ranking of relative toxicity using an American- developed model called an Environmental Impact Quotient (EIQ).

"What this study cared about was the association between higher use and lower - it was more of a comparison," she said.

Magoon found the highest associations between the insecticide category of pesticides and illness. "When you have areas of higher insecticide use you do see a higher chance of having a specific health outcome," she said.

"I do think it raises red flags," she said. While the percentage increases aren't large, "when you are dealing with newborns, it is not something you want."

THE MANITOBA HEALTH database shows that a male baby in an average income area in an area where there is average pesticide use has a 32.7 per cent chance of being born with a perinatal condition such as jaundice, respiratory distress, a low or high birth rate, or abnormal gestation.

The average insecticide use developed for the purposes of this study is 2.4 per cent of the CCS acreage receiving an insecticide treatment. In areas where that average insecticide use was doubled, the incidence of perinatal disorders in males was 36.7 per cent. In females, the percentage of babies born with perinatal conditions rose from 30.4 per cent in areas of average use to 33.9 per cent where insecticide use was doubled.

Similar trends emerged for congenital anomalies and eye disorders. "I feel there's something going on," Magoon said. "When you see both of the outcomes that have to do with infants having significant effects - even when you are looking at the whole population across the rural south - that raises an issue."

The research noted a correlation between the incidence of male cancers and pesticide use, but the increase was not high enough to be considered statistically significant.

Magoon's study also revealed a slightly reduced level of female circulatory diseases - dropping from 16.7 per cent to 16 per cent in areas where pesticide use was double the average applications.

The correlation that Magoon's research found is consistent with epidemiological studies that show higher rates of health disorders attributed to certain pesticide use.

But there are also industry studies that specifically studied farm families, which showed no correlation between negative health effects and pesticide use.

Rene Van Acker, head of plant science at the University of Guelph, who served on the thesis panel critiquing Magoon's work said the study is an important example of how extensive data bases can be used to study policy questions.

"The study is a very good example of the value of extensive data bases and combining the Manitoba health database with the Manitoba crop insurance data base created a unique opportunity to explore some important public health questions," said Van Acker. "Unfortunately it is unique."

"What was interesting was how she managed to converge the two data bases in a way that allowed one to ask such interesting questions like 'Is there a significant relationship between pesticide use rate and health conditions in rural areas?'"

"This seems like a basic question and one that we should readily be able to explore but Jen was the first one in Canada to create a means for trying to answer that question."


© Copyright 2007, Ontario Farmer. The Organic Agriculture Centre of Canada (OACC) wishes to thank Ontario Farmer for permission to reproduce this article on our website.


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