SAFEGUARDS | Food NO. 123/16

SafeGuardS fruits and vegetables

On June 1, 2016, Regulation 40 CFR 180.680 was amended in order to establish tolerances of fluensulfone residue in or on various food commodities. Objections and requests for hearings must be received before August 1, 2016.

Fluensulfone or MCW-2, (5-chloro-2-(3,4,4-trifluorobut-3-enylsulfonyl)-1,3-thiazole is member of the fluoroalkenyl thioether group. It is widely used to control root-knot nematodes such as Meloidogyne javanica, Meloidogyne incognita, and Meloidogyne arenaria in cucumbers, melons, cantaloupes, and eggplants, which otherwise cause yield losses in excess of 20% in some crop species, with an estimated financial loss of at least USD125 billion per year. With the results of unfavorable toxicology and the ecology of chemical nematicides such as methyl bromide, aldicarb, and fosthiazate, fluensulfone has brought new challenges for nematode management.

To understand the metabolic pathway of fluensulfone, radio-labeling in either thiazole ring or butane side chains have been investigated in plants. Scientists found that thiazole sulfonic acid (TSA) and butane sulfonic acid (BSA) are major metabolites of fluensulfone. In order to protect human health from the abundant use of pesticides in foods, the United State Federal Food, Drug, and Cosmetic Act (FFDCA) authorized the Environmental Protection Agency (EPA) to establish tolerances or maximum residue limits. Since it is unclear how the tolerance levels of fluensulfone proposed in the March 16, 2016 Notice of Filing (Federal Register 2016-05952), Interregional Research Project Number 4 (IR-4) are to be established, ADAMA Makhteshim Ltd requested an amendment of the regulation regarding the filing of pesticide petitions (PP 5E8384 and PP 5F8351). Consequently, the tolerance expression is changed as per the petitioner’s requests, based on the sum of the parent, its metabolites and degradates. The amendment of the tolerance limit of each crop group lately published in the Federal Register of June 1, 2016 (FRL-9946-07) [1] is shown in Table 1. Compliance with the tolerance levels specified below, is to be determined by measuring only 3,4,4-trifluoro-but-3-ene-1-sulfonic acid. Reverse phase high performance liquid chromatography-mass spectrometry (LC-MS/MS) is required as the analytical enforcement method. Apart from the change of tolerance levels, the time-limited tolerance in carrot, according to the Federal Register of March 3, 2016 (FRL-992-10) is removed, then replaced with the permanent tolerance for root vegetables, except sugar beet (subgroup 1B) in the amendment as well.

Table 1. Tolerance limits of Fluensulfone including its metabolites and degradates in or on the food commodities.

Commodity Parts per million (ppm)
Berry, low growing (subgroup 13-07G) 0.3
Brassica, head and stem,(subgroup 5A) 1.5
Brassica, leafy greens (subgroup 5B) 9.0
Potato, chips 0.6
Potato, granules/flakes 0.8
Tomato, paste 1.0
Vegetables, cucurbits (group 9) 0.5
Vegetables, fruiting (groups 8-10) 0.5
Vegetables, leafy, except Brassica (group 4) 2.0
Vegetables, leaves of root and tuber (group 2), except sugar beet 30
Vegetables, root, except sugar beet (subgroup 1B) 3.0
Vegetables, tuberous and corm (subgroup 1C) 0.5

What do the changes mean?

This updates has the potential to affect agricultural producers, food manufacturers, and pesticide manufacturers.  The residue of Fluensulfone including its metabolites and degradates in or on the products destined for the US must not be found over the tolerance limits. To comply with food safety regulations, food producers should seek professional advice.

SGS is committed to keeping you informed of regulatory news and developments.  Leveraging our global network of laboratories and food experts, SGS provides a comprehensive range of food safety and quality solutions, including analytical tests, audits, certifications, inspections, and technical support. We continually invest in our testing, capability, and state-of-the art technology to help you reduce risk, improve food safety and quality. For further information, please visit our website:

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Amornpun Dajsiripun
Global Competence Support Centre Food Specialist
t: +66 2683 0541 ext 2423

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