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Health Canada and EPA Adopt OECD Calculator for Establishing Legal Limits for Pesticide Residues

In 2005, Health Canada’s Pest Management Regulatory Agency (PMRA) and EPA’s Office of Pesticide Programs (OPP) jointly released a spreadsheet to calculate statistically-based legal limits for pesticide residues, referred to as maximum residue levels (MRLs)1 or tolerances2.  The North American Free Trade Agreement (NAFTA) MRL Harmonization Working Group developed this spreadsheet to better coordinate the pesticide regulatory framework among NAFTA partners with the goal of minimizing trade barriers of pesticide-treated commodities between the United States and Canada.  

In addition to the NAFTA MRL spreadsheet, referred to as the “NAFTA MRL Calculator”, the NAFTA MRL Harmonization Working Group also released an accompanying guidance document containing instructions for using the spreadsheet, and a “white paper” that provided additional technical and explanatory material for the guidance document.  A slightly modified version of the NAFTA MRL Calculator was released in 2008.

In 2008, the Organization for Economic Cooperation and Development (OECD) formed an analogous Working Group with a similar goal of developing a statistically-based method for calculating MRLs using a spreadsheet, which would assist in coordinating the pesticide regulatory framework among OECD partners.  The members of this OECD MRL Working Group include some of the same individuals from the NAFTA MRL Harmonization Work Group, but also representatives from other international agencies responsible for regulating pesticides and other stakeholder OECD members. 

In November 2010, the OECD MRL Working Group finalized its MRL calculator, user guide, and supporting “white paper.”  were by The Working Group on Pesticides (WGP) officially approved the MRL spreadsheet and supporting documents, and in March 2010 they became available for download from the OECD web site. Exit EPA disclaimer

Both Health Canada-PMRA and EPA-OPP agree that the OECD MRL Calculator provides statistically robust and scientifically-defensible MRLs.  Beginning April 1, 2011, Canada and the United States will join the other OECD member countries in their use of the OECD MRL Calculator to establish pesticide MRLs.  The OECD MRL Calculator will replace and supersede the NAFTA MRL Calculator.  The OECD MRL Calculator and supporting documents also are available for download from the OECD Working Group on Pesticides web page.

More information about pesticide tolerances.


1Canadian terminology
2USA terminology

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