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MRLs and Tolerances Topics
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Tolerances and Maximum Residue Levels


Syngenta strives to assist growers and shippers by helping to solve complex maximum residue level (MRL) issues that they face in today's global economy. As a leading producer of quality crop protection products, we recognize the importance of having harmonized MRLs. Reducing impediments to trade due to inconsistent MRLs entails a multilateral and multinational effort by regulatory agencies, crop protection companies, grower organizations and others.

The Definition of MRLs
  • What MRLs Are:
    Maximum residue levels, also known as a maximum residue limits or tolerances, are a legally enforceable definition of the maximum concentration of pesticide residues that are allowed on an agricultural commodity at the point of market. MRLs are typically measured in parts per million (ppm). In other words, an MRL is measured by how many parts of pesticide are present per million parts of commodity.

  • What MRLs Are Not:
    Among the public, MRLs are frequently misunderstood to be a safety standard. It is important to note that MRLs are not a measure of toxicity; that is, they are not a measure of the point when residues will make a person sick. The toxicologically significant level is usually a great deal higher than the established MRL. Instead, MRLs are set and monitored to make sure growers are applying the pesticide according to government regulations.
The Challenge: Products Meeting US MRLs May Not Align With Foreign Market MRLs

Whenever a pesticide is registered for use on a food or feed crop, a tolerance or an exemption from the tolerance requirement must be established. In the U.S., the Environmental Protection Agency establishes tolerances after a thorough scientific review. The Food and Drug Administration and the U.S. Department of Agriculture conduct tolerance enforcement.

But the U.S. is not alone in establishing MRLs. As countries around the globe modernize their food supply requirements, they frequently establish their own national MRL lists. Some countries base their MRLs on a product's active ingredient, while other nations' MRLs are based on the parent compound plus any compounds that exist as the product breaks down. In addition, variability of agricultural practices, eating patterns, residue testing methodology, differences in crop groupings and names of crops cause further confusion and make the establishment of one residue level for the world very difficult.

Challenges for growers emerge when these foreign MRLs differ from the MRLs in the U.S. or when a foreign market does not have an MRL established for a crop protection product approved in the U.S. In such cases, growers can apply a crop protection product according to the label and be within the U.S. MRL limit, only to potentially have their crop rejected in a foreign country because of a residue violation. Unfortunately, this trend has increased over the last few years.

The Solution: Establish Synchronized MRLs Across the Globe
  • Codex Alimentarius Commission
    Governments around the world are cooperating to establish synchronized MRLs and minimize differing tolerances. This effort occurs on a bilateral basis as well as through multilateral international organizations, such as the United Nation's Codex Alimentarius Commission. Each year, numerous countries meet to establish Codex tolerances that can be used as an international MRL standard. Codex MRLs are especially helpful for countries that do not otherwise establish pesticide MRLs or that have a limited list and then defer to Codex MRLs for additional guidance.

  • The Private Sector: Pesticide Registrants and Grower Groups
    In addition to government efforts to harmonize MRLs, private-sector entities, including pesticide registrants like Syngenta and grower groups, also are seeking coordinated MRLs around the world. Pesticide registrants ensure that accurate and similar data is submitted for reviews in countries when new MRLs are being established, while grower groups offer comments to U.S. and foreign governments when pesticide regulatory changes are announced. Often, if comments are submitted early enough, MRLs can be adjusted so they correspond with other global MRL standards.

Monitoring and Enforcing MRLs

MRL control and enforcement differ from country to country. The testing of residue levels could happen at any time, and the process is ever-changing. Most systems involve the federal, state or local/provincial government collecting samples of a variety of food products, including both domestic and imported goods, and sending them to scientific labs to detect residues. When a residue exceeds an established MRL, the country may notify the retailer, producer, shipper or grower and seek an explanation of the violation. A record of violations is typically retained, and if the source is a repeat violator, additional sanctions may be applied. In other cases, if residues are deemed too high at the port, commodities will not be able to enter the country or region. Such shipments may be returned or destroyed.

For More Information

Contact the Syngenta Customer Center at 1-866-SYNGENT(A) (796-4368) or your local Syngenta representative for more information about MRLs and our crop protection products. You also can visit our FarmAssist and Syngenta Crop Protection Web sites.



Users of this information are advised that national, regional and international regulations affecting permissible Maximum Residue Levels (MRL) frequently change. Although this information is updated periodically, the user accepts that the information on Maximum Residue Levels in it may not be completely up-to-date or error free. Additionally, commodity nomenclature and residue definitions vary between countries, and country policies regarding deferral to national, regional and international standards are not always transparent. This information is intended to be an initial reference source only, and users must verify any information obtained from it with the relevant regulatory agencies in the market of interest prior to the sale or shipment of any products. Syngenta shall not be liable for any loss or damages, including, but not limited to, direct or consequential damages, loss of profit, loss of business, loss of revenue, demands, claims, actions, proceedings, damages, payments, expenses, or other liabilities occasioned to or suffered by any person acting or refraining to act as a result of the information relating to Maximum Residue Levels contained on this Web site, or otherwise caused by or arising, in whole or in part, in any way from user's use of this information.

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