Pesticide residue legislations challenge international trade of food and feed
Diversity of international pesticide regulations
June 2020. The residues of pesticides in food and feed are regulated quite differently worldwide, which poses numerous challenges for international trade. A new Eurofins publication in the Cereal Technology (Nader, WF, Maier, M., Miebach, M. and Linder, G .: Pesticide residue legislations challenge international trade of food and feed. Cereal Technology 2: 84-99 (2020)) describes this problem and refers to the diverse maximum residue limits (MRLs) as well as to certain chemical compounds in food that are classified as pesticide residues, which is not necessarily the case. Frequently they are of natural origin or are formed during food processing by chemical reactions. Examples are bromide in Brazil nuts, phthalimide in herbs and spices, mepiquat in roasted coffee and indole-3-acetic acid in cereal grains. Chlorinated process water leads to contamination with chlorate during food production.
"Pesticide residue legislations challenge international trade of food and feed"*
The complete article was published in the magazine Cereal Technology 2: 84-99 (2020). The publication is available here for free download.
*Authors: Werner Nader, Michelle Maier, Marco Miebach and Gabriel Linder
Diversity of maximum residue limits worldwide
The economic impact of the different pesticide regulations is particularly evident in the international rice trade. The lowering of the EU maximum residue level for the fungicide tricyclazole from 1 to 0.01 mg/kg shifted the EU Basmati rice imports from the main source country India to Pakistani imports in early 2018. Revenue losses for Indian rice exporters are estimated at $ 232 million. In the United States, the tolerance for tricyclazole is 3 mg/kg. In contrast, rice with residues around 0.01 mg/kg of the fungicide isoprothiolane causes import alerts in the USA, but it is totally fine for the EU market in concentrations up 6 mg/kg.
Residues of pesticides in organic products
Synthetic pesticides are not allowed in organic farming and therefore no residues should appear in organic products. However, pesticides are now almost ubiquitous due to their frequent use and can also be introduced into organic products through cross-contamination. Pesticide residue traces around 0.01 mg/kg are assessed differently in the EU member states, as there are no specific harmonised organic EU residue levels. While the BNN orientation value for pesticides of 0.01 mg/kg (of the German Association of Organic Processors, Wholesalers and Retailers) is sometimes accepted for up to two pesticides, even traces below 0.01 mg/kg are rated as deliberate pesticide use in other member states such as the Netherlands and products are rejected and/or involve a further investigation. Depending on the member state, importers of organic food and feed are treated differently.
Residues, impurities or natural substances?
Numerous substances are listed in the EU MRL regulation (EC) No. 396/2005), which are considered residues of pesticides or growth regulators or metabolites thereof, but are necessarily not. Indole-3-acetic acid is a natural plant hormone, an auxin. In synthetic form, it is used as a rooting hormone, but is not approved in the EU. The maximum residue level is 0.1 mg/kg. Cereal seeds contain very high concentrations of the hormone, with rice over 1 mg/kg and maize even above 70 mg/kg. Cereal grains therefore do not comply with this requirement because of their natural content.
Phosphonic acid or phosphonate is considered in the EU MRL regulation a residue from applications of the plant strengtheners potassium or disodium phosphonate or a metabolite of the fungicide Fosetyl-aluminum. MRLs are between 2 mg / kg (e.g. in cereals and legumes) up to 500 mg / kg for nuts. According to the BNN concentrations above 0.05 mg/kg already indicate that chemicals might have been applied, which are not compatible with the EU regulation for ecological agriculture. But new scientific studies from the USA reveal that phosphonic acid naturally occurs in significant concentrations in the environment and is formed by microorganisms in a biogeochemical cycle by reducing phosphate. Plants efficiently take up and accumulate phosphonate. Phosphonate found in food is therefore not necessarily a residue from a pesticide application.
Other similar examples for such compounds are shown in the publication, which has been reviewed and approved by independent experts (peer review).
Do you have any further questions?
Two authors of the publication, Dr Werner Nader and Dr Marco Miebach, will be happy to assist you.
The publication appeared in the Cereal Technology (2/2020) and can be downloaded here for free.
