The results of animal studies, together with mechanistic considerations, are used in an evidence-weighting approach to decide if a pesticide is likely to pose a cancer risk to humans. The OECD Working Group on Pesticides functions as a vehicle for global cooperation and facilitates the exchange of information and the alignment of approaches to pesticide evaluation. When the risks to human health and the environment are acceptable and the pesticide has an acceptable value, that is, the pesticide can be used safely and effectively without any modification to its proposed or existing uses based on the conditions of registration, which include following the instructions on the label, the pesticide can be used grant pesticide registration. To verify that Canada's MRLs are being respected, the Canadian Food Inspection Agency (CFIA) examines domestically produced food and imported food for pesticide residues.
This framework also applies to registration decisions for biopesticides (microbial and pheromone pesticides), non-synthetic pesticides (plant extracts or other substances of natural origin) and devices, with specific modifications for each situation. Maximum residue limits are set for each pesticide, crop use in Canada, or for pesticides present in food imported into Canada (in other words, in food crops or directly in food products). A lifetime cancer risk of less than 1 × 10−6 (one in a million) is generally an acceptable risk indicator for the general population when exposure occurs through pesticide residues in or on food, and for people who are unintentionally exposed. An examination of environmental chemistry and destination considers the potential for pesticide exposure.
The first step is to learn about the pests you have and the options available to control specific pests. This process is governed by the Pest Control Products Act, which provides decision-making authority based on scientific risk assessment and risk management. The endpoints for acute and chronic effects are derived from laboratory and field studies that characterize the toxic response and dose-effect relationship of the pesticide and its main transformation (degradation) products. Similar to the approach to assessing risks to human health, environmental risk assessment evaluates exposure (environmental fate and behavior) and hazard (toxic effects on organisms) and characterizes the risks posed by pesticides.
Based on the results of the evaluation phase, a strategy is developed to manage the risk of a pesticide. This program collects complete pesticide sales data annually and is mandatory for pesticide registrants. This includes implementing changes to existing data requirements to support pesticide records, such as removing the routine requirement for certain animal studies, along with exploring how to incorporate more pharmacokinetic and toxicokinetic information. In addition, PMRA applies additional protective factors if justified by the pesticide hazard profile or the quality and integrity of the underlying data.
