In water or soil, pesticides are present everywhere. Scientists have known for years that massive use is harmful to health. But this toxicity is only calculated individually, each chemical substance having its own concentration limit not to be exceeded.
“In the environment, there are dozens of kinds of pesticides. What we wanted to evaluate is the danger that several low concentrations could represent, if it could be as great as a single high concentration,” explains professor in the biology department Luc Gaudreau, who led this study.
By proving that small quantities of several pesticides can have an effect equivalent to a large concentration of just one of them, a new health risk is revealed. Especially since the products studied are insecticides, fungicides and herbicides used extensively in Canada.
The effects of interactions between pesticides could be very significant, according to Mr. Gaudreau.
In contact with the cells making up the human body, pesticides cause direct or indirect mutations in the DNA. If it happens in the wrong genes, these changes can cause cancer.
This is explained by the way pesticides act, which attack the same molecular targets. When small amounts of several products attack cells, it has the same effect as a large concentration of just one of them.
“The more you live in a region where agriculture is intensive, the greater the risks,” comments Mr. Gaudreau.
An openness to other studies
This discovery is not the end, but the beginning of pesticide research. Although several types have been banned in recent decades, knowledge about these products still remains insufficient, according to Mr. Gaudreau.
“We don’t know enough about the effects of pesticides, so we tend to overuse them until we realize that they are harmful.”
To overcome this, research on the subject should be intensified, but also their consequences should be studied differently.
“If we talk about cancer, there are not many epidemiological studies. In France, (…) it is very clear that farmers’ cancers are associated with this, these studies are much clearer,” he recalls.
Mr. Gaudreau would therefore like to intensify his research, by increasing the number of combinations of pesticides studied. But this takes time, since the number of permutations increases according to the quantity of products studied, and this remains complicated to carry out in the laboratory, laments the professor.
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Pesticides don’t just increase the risk of cancer. According to the National Institute of Public Health of Quebec, the risks of leukemia, congenital malformations, Parkinson’s disease or Alzheimer’s could also be increased in the event of too strong and prolonged contact.
The final objective of the most recent study would be to better understand these products by carrying out larger-scale studies, taking into account that pesticides can be added together. Mr. Gaudreau hopes to have thus opened the door to many other studies of this type, which could advance the question of the use of these chemical substances.
“The big question is to know what harmful effects this can have, in order to then make rational choices about the use of pesticides and their alternatives,” concludes Mr. Gaudreau.
