The FDA recently released new guidelines concerning levels of both gluten and arsenic in food products. On August 2, the FDA’s final rule for the definition of “gluten free” was published in the Federal Register. Previously, there was no limit to how much gluten a food product could contain and still use the labels “gluten free,” “free of gluten” or “without gluten.” The definition sets the limit of gluten that a “gluten-free” food product may contain at 20 ppm or less. The ruling applies to all food products regulated by the FDA, including dietary supplements and imported products. Meats, poultry and the majority of egg products, and most products containing alcohol are regulated by the USDA and the Tobacco Tax and Trade Bureau, respectively. The final rule aligns with the limits set by the EU for gluten. Manufacturers will have until August 5, 2014, to comply with the new requirements.

Avoiding gluten has become crucial to certain consumers over the past few years as more research is conducted and publicized on the potentially harmful effects of gluten. To address the dietary issues of individuals who have celiac disease or gluten sensitivity, food manufacturers have increasingly introduced food products without gluten. However, these labels can be misleading. Food products labeled “gluten free” may actually contain gluten due to contamination during processing, particularly from using shared manufacturing equipment. Crop rotation can also result in gluten contaminating a “gluten-free” product.

The 20 ppm limit the FDA has decided on was set because validated analytical methods to detect gluten at levels lower than 20 ppm are not currently available, according to FDA spokesperson Shelly Burgess. The FDA has not specified a method for gluten testing. Sandwich ELISAs are the most commonly used test to quantitate gluten in food products, according to the Institute of Food Technologists (IFT). MS-based and PCR-based methods can also be utilized, although they are generally used as confirmatory techniques. PCR is not ideal because it recognizes DNA instead of proteins. “By definition, gluten is a protein extract, and thus effort is made to not include DNA or other nucleic acid biomarkers,” explained Ms. Burgess. “Hence, quantification is at best dubious by PCR, and it is possible that high quality gluten may have no DNA.”

Adenosine triphosphate swab tests can also be used, although they have a history of producing false negatives, according to the IFT. In 2011, AOAC Official Method 991.19 was approved for measuring the gluten level in foods. The ELISA test utilizes the R5 monoclonal antibody, which binds to gluten and similar prolamins. The AOAC’s Research Institute has only certified R-Biopharm’s RidaScreen Gliadin method as a Performance Tested Method. For measuring gluten levels, the FDA recommends use of the R-Biopharm test or the Morinaga Institute of Biological Science’s Wheat Protein ELISA Kit, which was validated in a study conducted by Japan’s Ministry of Health, Labor and Welfare. The FDA plans to use these two tests together when it conducts post-market monitoring activities of gluten levels, such as facility inspections, food label reviews and complaint investigations.

As part of the rule, manufacturers are not required to test for gluten. The FDA expects that the increase in gluten testing by manufacturers that opt to use gluten-related labeling and did not previously test the gluten content of their food product will cost $5.8 billion annually, according to Ms. Burgess. Manufacturers have several options for testing, according to Ms. Burgess. They can conduct gluten testing in house, contract with a third-party lab for testing or request certificates of gluten analysis from ingredient suppliers.

Despite being the generally accepted testing method for gluten detection, there are limits to sandwich ELISAs as well, according to the IFT. The tests do not adequately detect intact gluten proteins in fermented and hydrolyzed foods, such as sourdough bread, cereal and vinegar, because they require two antigenic epitopes, which such foods do not contain. The FDA plans to issue a separate ruling on gluten testing in fermented and hydrolyzed foods at a later date.

In July, the FDA also proposed an action level for inorganic arsenic in apple juice. An action level is the level that the FDA deems safe for public health and takes into account when contemplating a product recall. The action level was set at 10 ppb, which is also the level the EPA has set for arsenic levels in drinking water. The FDA proposed the action level to provide guidance to the industry. “We are taking this action because we believe this level will help keep out of the food supply, even the occasional lot of apple juice with arsenic levels above those permitted in drinking water,” said Ms. Burgess. In 2012, the FDA conducted tests for arsenic in 94 apple juice samples and concluded that 100% of samples met the limit for inorganic arsenic, which is arsenic in its carcinogenic form, and 95% of samples contained 10 ppb or lower of total arsenic. The 10 ppb limit is based on sampling and a risk assessment of inorganic arsenic in apple juice published in December 2012.

The FDA will not require manufacturers to test their apple juice for arsenic at this time. “The agency’s own tests have shown the levels to be very low over time,” said Ms. Burgess. The agency will, however, recommend that the industry adopt its own testing standards. Traditionally, the FDA has relied on FDA Elemental Analysis Manual method 4.11, which utilizes HPLC followed by ICP-MS to test for total and inorganic arsenic in a variety of sample types, according to the FDA. If levels of arsenic are present at levels higher than 10 ppb, samples will be tested further for inorganic arsenic levels. Similar to gluten levels, the FDA will conduct post-market monitoring activities of arsenic, which will primarily involve retail sampling.

The FDA is currently accepting comments on the proposed action level. When the comment period concludes, the agency will re-evaluate the limit and publish a final action level. It is unknown when the final action level will be published, since this will vary due to the amount of comments and the time it takes to review them. However, the FDA anticipates that manufacturers will begin additional testing for inorganic arsenic in apple juice before the final action level is published.