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Questions and answers: Regulation of nitrification and urease inhibitors

What are nitrification and urease inhibitors?

Nitrification and urease inhibitors are nitrogen management products that can be applied with many forms of nitrogen-based fertilizers. Nitrification and urease inhibitors belong to a class of products knowns as nitrogen stabilizers. These products increase nitrogen-use efficiency by reducing losses through volatilization, leaching, run-off and denitrification allowing for more of the applied nitrogen fertilizer to be available to the crop. Urease inhibitors act on the enzyme urease, which is endemic in fields and an abundant soil enzyme. Nitrification inhibitors delay the conversion of ammonium to nitrate by temporarily inhibiting the ammonium monooxygenase enzyme within the Nitrosomonas bacterium.

Why is the regulatory oversight of nitrification and urease inhibitors changing?

A review of the Fertilizers Act and the Pest Control Products Act revealed overlapping authorities in the regulation of nitrification inhibitors that act on soil bacteria.  To improve efficiencies and clarify the regulatory pathway to market, the Canadian Food Inspection Agency (CFIA) and Health Canada's Pest Management Regulatory Agency (PMRA) agreed that both nitrification and urease inhibitors will be regulated by the CFIA alone, as soil supplements.

How did the PMRA and the CFIA arrive at this decision?

The PMRA determined that the scientific risk assessments conducted as part of the CFIA's registration process adequately address the health and environmental risks and benefits associated with these products. Consequently, the Pest Control Products Regulations (PCPR) will be amended to exempt nitrification inhibitors from the provisions of the Pest Control Products Act.

What type of data is required to demonstrate the environmental benefits of urease and nitrification inhibitors?

The CFIA in consultation with the impacted industry have developed baseline data requirements to substantiate environmental protection end points. Examples of admissible data include but are not limited to nitrogen speciation curves, volatilization data [ammonia (NH3), nitrous oxyde ( N2O)], nitrate leaching data, etc.  In case of volatilization data for nitrous oxide (N2O), both direct and indirect measurement of emissions is required. These data requirements are intentionally outcome-based (that is, they do not prescribe specific methods or approaches) in order to offer companies the flexibility in substantiating the environmental protection claims.

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