Know Your Limits: How Pesticides Protect Your Food Supply

By Dilia Narduzzi

Before a new pesticide is brought to market, it undergoes rigorous testing to make sure that handling it is safe for farmers and any residue left on the plant is within certain allowable limits, i.e. safe for human consumption. In June of 2021, a new fungicide, picarbutrazox, used on canola and corn crops, had what’s called its maximum residue limit (MRL) imposed by Health Canada’s Pest Management Regulatory Agency (PMRA). All pesticides used on crops must go through this testing process. While each country sets its own MRL, they are coordinated worldwide.

Prices for fruit and vegetables would be 45% more if “pesticides weren’t used to increase crop yields.”

But how does the system work? The key aim is to “minimize human exposure. The rule of thumb is to use as much as you need to achieve the end product, which is to kill the bug that’s jumping around on your lettuce, but use no more than that,” says Dr. Leonard Ritter, a professor in the School of Environmental Sciences at the University of Guelph and an expert in pesticides and their safety protocols. Before any farmer can use the product, the company manufacturing it must go through trials. Results of the trails are submitted to organizations like Health Canada’s PMRA and they’ll either decide the “chemical can be used safely at the concentration that’s being proposed or it will be rejected. We’re not going to approve chemicals that cause cancer or are inherently explicitly toxic,” says Dr. Ritter.