US Environmental Protection Agency (EPA) Revises MRL for Thiram in Avocadoes
SAFEGUARDS | Food NO. 107/15
Regulation of 40 CFR 180.132 has been amended to establish a revised tolerance level for thiram in, or on, avocadoes. The change entered into force on 19 June 2015. Objections and requests for hearing must be received by addressing the docket with ID number EPA-HQ-OPP-2014-2049 before 18 August 2015.
Thiram (tetramethylthiuram dissulfide) belongs to a group of dithiocarbamate fungicides. It is used as a seed protectant and foliar treatment on fruits, vegetables, ornamentals and turf crops to control a number of fungal diseases, as well as to protect harvested crops from deterioration by fungal infection during storage and transport.
To ensure human health and food safety, the Federal Food, Drug, and Cosmetic Act (FFDCA) allows the Environmental Protection Agency (EPA) to establish tolerances that represent the maximum residue anticipated from the legal use of the pesticides on commodities. At tolerance levels, consumers should not be at risk of harm, especially to infants and children, through dietary exposure, drinking water and in a residential setting. However, occupational exposure is not included for consideration.
In making their tolerance decisions, the EPA tries to harmonize US tolerances with international standards, with particular reference to Codex Alimentarius Commission (CAC), according to FFDCA requirements. Unfortunately, the CAC has not set a MRL for thiram in any food. Therefore, in December 2014, the EPA accepted the proposed tolerance level, without full toxicological evaluation of thiram from petitioner, in or on avocadoes at the concentration of 8 ppm. The EPA has evaluated the risk posed by thiram to humans based on the organization for Economic Cooperation and Development (OECD) Tolerance Calculation Procedures. As a result, the tolerance level for thiram increases from 8 ppm to 15 ppm, in or on avocado, as shown in Table 1. This amendment becomes the default safety guideline for crop production, animal production, food manufacturing and pesticide manufacturing to regulate growers, food processors, food handlers and food retailers.
Regarding analytical methodology for dithiocarbamate residues in fruits and vegetables, these compounds are easily decomposed into carbon disulphite (CS2) by using hot acid-digestion. The formation of CS2 is collected for its determination by spectrophotometry or gas chromatography (GC). To comply with US regulations, the spectrophotometry technique is used to enforce the tolerance express of thiram.
Table 1 Tolerance level for Thiram in or on avocado 
Tolerance level (ppm)
What do the changes mean?
This update has the potential to affect agricultural producers, food manufacturers, and pesticide manufacturers. All avocadoes destined for the US must, with effect from 19 June, meet the new MRL, as listed in Table 1. As the MRLs have been increased, this should have no immediate impact, but if in doubt, food producers and manufacturers should seek professional advice.
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