Investigating the Suitability of Semicarbazide as an Indicator of Preharvest Nitrofurazone Use in Raw Chicken

Abstract

Semicarbazide (SEM) is the U.S. Food and Drug Administration's official marker for nitrofurazone use in food animals. The U.S. Department of Agriculture Food Safety and Inspection Service conducted a study to evaluate the source of SEM that was identified by a U.S. trading partner in a subset of chicken samples presented for inspection, even though nitrofurazone has been banned from use in U.S. food-producing animals since 2002. The study design included analyses to detect and quantify total and bound SEM in chicken collected from the eight U.S. establishments that were associated with the reported detection of SEM. Samples were collected immediately following evisceration, chilling, and cutting carcass into parts (cut-up). Although antimicrobial interventions (processes to reduce pathogen concentrations) are typically used at all three of these processing steps, the product contact time during chilling is significantly longer (hours versus seconds) than during evisceration and cut-up. In addition, parts were analyzed after 0, 10, 20, and 30 days of frozen storage. No postevisceration samples tested positive for SEM; however, most samples collected postchilling and after cut-up tested positive. The absence of SEM in postevisceration samples and detection in the subsequent postchilling samples and after the cut-up samples suggest that the detection of SEM in the sampled products is not indicative of preharvest nitrofurazone use and may be a result of postharvest processing in these establishments. HIGHLIGHTS

Presence of nitrofurans and their metabolites in gelatine

“…Some examples of these steps include the following: (1) to address the issue of azodicarbonamide in flour, testing for the marker metabolite for nitrofurazone in breaded food products should be carried out on only the animal tissue part of the product, (2) to address the issue of natural occurrence of SEM in shellfish, only the inner core of products such as shrimps, prawns and crayfish should be tested for the marker metabolite for nitrofurazone, as the naturally occurring SEM occurs only in the outer part and (3) to address the issue of SEM being produced during food processing, the sample should be extensively washed with a range of organic solvents to remove any free SEM from the sample prior to the hydrolysis and derivatisation step for protein‐bound SEM as the marker metabolite for nitrofurazone. The latter step is the one relevant to analysis of products, such as gelatine, for SEM as a marker metabolite of nitrofurazone; however, the finding that SEM generated during food processing may become bound to macromolecules in the food product (Hoenicke et al., 2004; Johnston et al., 2020) renders this step not useful in distinguishing the source of any measured SEM in such samples.…”

“…This author also described the formation of SEM in the presence of hydroxyurea. Johnston et al (2020) reported on a study to determine whether SEM was formed in chicken during processing, disinfection, chilling and freezing. The study arose because exported poultry was rejected at the point of entry by a U.S. trading partner due to the presence of SEM and the associated assumption that the SEM was indicative of nitrofurazone use.…”

Facile synthesis of 14C‐nitrofurazone from 14C‐urea

“…Further, SEM is naturally produced in shrimp, crayfish, and other crustaceans 6–9 . These reports indicate that SEM cannot be used to reliably confirm nitrofurazone abuse in food‐producing animals 4,5,10 . Therefore a specific marker of nitrofurazone that is capable of differentiating treated and untreated farm animals is highly desired as use of semicarbazide as a marker has impacted trade of animal food products at ports of entry 4,5,10 .…”

“…[1][2][3] Due to risks to human health regulatory agencies including the European Commission, the U.S. Food and Drug Administration, the Thailand Ministry of Health, and the New Zealand Food Safety Authority, have explicitly prohibited the use of nitrofurazone in food-producing animals. 5 Additionally, regulatory agencies monitor the illegal use of, or inadvertent exposure to, nitrofurazone by measuring tissue bound semicarbazide (SEM) because parent nitrofurazone is rapidly metabolized. 5 However several publications have demonstrated that the occurrence of SEM in food is not merely attributable to nitrofurazone use.…”

“…5 Additionally, regulatory agencies monitor the illegal use of, or inadvertent exposure to, nitrofurazone by measuring tissue bound semicarbazide (SEM) because parent nitrofurazone is rapidly metabolized. 5 However several publications have demonstrated that the occurrence of SEM in food is not merely attributable to nitrofurazone use. [6][7][8][9] That is, a plethora of evidence is available showing that there are many non-nitrofurazone sources of SEM; for instance SEM may originate from food ingredients, food packaging, and food processing.…”