A fungicide widely used by prairie farmers to combat ascochyta blight in chickpeas and other pulse crops has been linked by U.S. researchers to a blood condition that can lead to cancer.
Chlorothalonil is the active ingredient in Bravo 500, a fungicide manufactured by Syngenta.
The product is labelled for use on a range of pulse crops, including chickpeas, lentils, dry peas and field peas, as well as wheat for fusarium head blight. It is now mainly used on chickpeas in Western Canada, having been replaced over the years by newer products.
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A spokesperson for Syngenta said the company is confident the product is safe.
“We constantly review the science behind our products, it never stops, and we continue to stand behind the safety of all of our products,” said Judy Shaw, director of government and public affairs.
The study was conducted by a team of researchers from the U.S. National Cancer Institute at the National Institutes of Health in Bethesda, Maryland.
It looked at 678 male licensed pesticide applicators and found that exposure to certain pesticides can double the risk of developing a blood condition known as monoclonal gammopathy of undetermined significance (MGUS), a pre-cancerous condition that can lead to multiple myeloma, a cancer of plasma cells in the bone marrow.
The incidence of MGUS among the pesticide applicators over 50 years of age was 1.9 times higher than a sample of nearly 10,000 males in the general population in Minnesota.
The researchers examined the relationship between MGUS and 50 specific pesticides and identified a significantly higher risk associated with three products: dieldrin, carbon tetrachloride (neither of which are registered for use in Canada) and chlorothalonil.
“Our study is the first to show an association between pesticide exposure and an excess prevalence of MGUS,” lead researcher Ola Landgren said in a news release.
The study was published in the June 18 issue of the Blood, the journal of the American Society of Hematology.
Jonathan Akins, Syngenta’s manager of toxicology for North America, said it’s important to note that chlorothalonil has been approved by the U.S. Environmental Protection Agency, Canada’s Pest Management Review Agency and similar organizations around the world.
“There has been lots of research that indicates it’s safe when used according to label directions.”
He added that a study published by the same authors in 2008, looking specifically at chlorothalonil and cancer, concluded the product was not associated with any incidence of any type of cancer in humans.
Akins said Syngenta is reviewing the latest study and has questions.
“There are some limitations associated with the study and we need to dig a little deeper into the methodology,” he said.
For example, while the subjects of the study came from Iowa and North Carolina, the control group came from Minnesota, which raises questions about the validity of the comparisons.
Coincidentally, on June 10, Health Canada’s Pest Management Regulatory Agency (PMRA) expanded Bravo 500’s label to include new uses on certain fruits and vegetables.
