How does the PMRA identify the hazards and evaluate the health risk associated with 2,4-D?
In order to identify the potential hazards of a chemical, it is tested at dose levels that are many times higher than the level to which humans would be exposed, and testing is done over both short and long term durations and via different routes of exposure (e.g., dietary vs. dermal [skin] exposure). Although a given chemical may be toxic at high doses, lower doses are less toxic. Part of the risk assessment is to apply safety factors so that under conditions of normal use, there is a sufficient margin of safety (typically a 100-1,000 fold difference) between the potential exposure levels to humans and any toxic effect noted in laboratory tests. Additionally, as part of the assessment of a pesticide, the effects of a single, multiple, or life-time exposure are examined. When a registered product is used according to label directions and when good hygiene practices are followed, exposure will usually be minimal and pose no risk.
