Chapter 1
Overview Chapter
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Fadwa Al-Taher Although Americans have one of the safest food supplies in the world, the new millennium has brought challenges to the realm. The globalization of the food supply, the discoveries of intentional contamination of the food supply, the growing volumes of imports, and advances in production and distribution methods require updated approaches to protecting our food supply from unintentional and deliberate contamination. The U.S. Centers for Disease Control and Prevention (CDC) estimates 76 million food-related illnesses, 325,000 food-related hospitalizations and 5,000 food-related deaths occur in the U.S. each year.. The number of food borne illnesses associated with fresh produce is on the rise. Leafy greens have become one of the most common sources of food borne outbreaks in the U.S. Increased attention has been focused on pathogenic microorganisms The chapter “Microbial contamination of fresh produce” looks at E. coli and Salmonella contamination of lettuce, spinach and other greens occurring in the fields or at processing plants. The increase of bacterial contamination in produce has caused microbiologists, epidemiologists, and chemists to work quickly to find methods for the rapid detection and control of the causative agents and the prevention of illnesses associated with these pathogens. Research is being conducted on new methods to control bacteria on produce and in biofilms without compromising the quality of food. This is discussed in the chapter “Inactivation of microbial contaminants in fresh produce.” Development of antimicrobial chemicals that can help ensure the safety of produce is underway. Immunoassays and PCR detection methods have been improved in terms of accuracy and speed to determine the cause of an outbreak. In-line rapid detection of microorganisms in produce wash and/or rinse solutions, irradiation of produce, surface pasteurization treatments of produce and cold plasma technologies are some novel technologies that have been developed to prevent or reduce pathogens from produce while preserving eating quality. With advances in analytical detection, chemists are now capable of analyzing for and detecting more chemicals at much lower concentrations in more foods due mostly to hyphenated techniques as is pointed out in “When philosophies collide: Dealing with very low levels of chemicals in food.” Questions arise as to whether a chemical detected at parts per billion levels © 2009 American Chemical Society Al-Taher et al.; Intentional and Unintentional Contaminants in Food and Feed ACS Symposium Series; American Chemical Society: Washington, DC, 2009.
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2 poses more health problems and concerns about the food supply for consumers than those chemicals detected at the parts per million level. The “U.S. Food and Drug Administration’s program for chemical contaminants in food” provides an overview of the chemicals of concern to the agency. Chemicals that may enter the food supply are food additives (colors and preservatives), food contact chemicals (food packaging materials, additives, Bisphenol A), agrichemicals (pesticides and veterinary drugs), mycotoxins, thermally-processed induced chemicals (acrylamide, furan, heterocyclic aromatic amines), environmental contaminants (heavy metals), and food allergens. Two chapters, “Effect of heatprocessed foods on acrylamide formation” and “Furan in thermally processed foods,” address specific chemicals that form as a result of heat treatment of food. It is difficult to determine a zero threshold for chemicals in food and difficult to explain acceptable tolerances to consumers. Toxicologists are in demand to supply more animal data and better ways to extrapolate to the low levels humans might be exposed to. Although safe levels of human exposure have been set for many chemicals, most people are concerned when new chemicals have been identified in their food and those chemicals have demonstrated potentially adverse chronic effects such as neurotoxic effects (acrylamide) and reproductive effects (dioxins) at high levels, but the effects of low level chronic exposure are uncertain. As of yet, there has been no known treatment for life-threatening food allergens, only prevention of allergic reaction by avoidance of exposure to the allergen. Food allergy affects about two percent of the population in the U.S. Food labeling of the presence of allergens educates sensitive consumers regarding products they should avoid consuming. Unintentional crosscontamination during manufacturing can occur and thus, it is important to discover novel approaches to monitoring food for undeclared allergens. Enzyme-Linked Immunosorbent Assay (ELISA) has been used traditionally for screening for undeclared allergens in foods, but it often gives ambiguous results due to cross-reactivity. Alternative methods are needed for confirmation. Mass spectrometric methods, such as what is discussed in the chapter “Detection and confirmation of food allergens using mass spectrometric techniques: Characterization of allergens in hazelnut using ESI and MALDI mass spectrometry,” have recently been introduced as detection and confirmatory tools for many potential allergenic contaminants. Mass spectrometric methods offer specificity, sensitivity and multi-target identification and quantification. Some allergens that have been investigated using mass spectrometry include ovalbumin in egg; tropomyosin in shellfish; Ara h1, Ara h2, and Ara h3 in peanut; and Į-S1 casein and ȕ-lactoglobulin in milk. Mycotoxins, secondary metabolites produced by certain fungi, occur naturally, and can contaminate food during growth in the field, processing, transportation or storage. “Mycotoxins of concern in imported grains” is an example of the occurrence of mycotoxins and the characteristics and formation of the various mycotoxins is discussed. Mycotoxins are considered both poisonous and chronic hazards and are best avoided by implementing good agricultural and manufacturing practices. Many mycotoxins are stable to heat and food processing procedures. Consumers may exhibit various toxicological
Al-Taher et al.; Intentional and Unintentional Contaminants in Food and Feed ACS Symposium Series; American Chemical Society: Washington, DC, 2009.
Downloaded by 80.82.77.83 on May 23, 2018 | https://pubs.acs.org Publication Date: December 17, 2009 | doi: 10.1021/bk-2009-1020.ch001
3 outcomes from ingestion. Historically, efforts have been undertaken to minimize mycotoxins in the food supply by establishing guidelines and action levels and monitoring the food supply for mycotoxins. Regulatory action will be taken against products that exceed the action levels for a mycotoxin. Some mycotoxins of greatest concern are aflatoxins in corn, peanuts, tree nuts, rice and cottonseed; fumonisins in corn, wheat, barley, and rice; and ochratoxin in wheat, barley, oats, rye, sorghum peanuts, wine, beer, and raisins. The European Union (EU) action limits for mycotoxins are lower compared to those established action limits in the United States. This can cause problems for international trade. For example, the EU has set an action level for Ochratoxin A in imported grains to be 5.0ppm. The U.S. has not established a limit as yet. Food imports to the U.S. have almost doubled in the past decade, from $36 billion in 1997 to more than $70 billion in 2007. Because of reduced budgets, the number of FDA inspectors at the Office of Regulatory Affairs dropped from 1,642 in 2003 to 1,389 in 2005, while food imports rose from 9.3 million shipments per year to more than 13.8 million shipments annually. The FDA inspectors sample just 1.3 percent of all imported food shipments entering the country and perform few on-site inspections of foreign farms and food processing plants. Since there are not enough inspectors at the borders, there have been incidents of food imports entering the U.S. unapproved, The FDA is responsible for inspecting all imported foods except for meat and egg products, which are regulated by the Food Safety and Inspection Service, part of the U.S. Department of Agriculture. “Dealing with intentional and unintentional contaminants in meat and poultry products regulated by the USDA/FSIS” demonstrates the economic concerns and what happens when there is a recall. In the time frame of October 2006 through May 2007, the FDA found that farm-raised seafood imported from China was contaminated with antimicrobial agents unapproved in the U.S. (nitrofuran, malachite green, gentian violet, and fluoroquinolone). Nitrofuran, malachite green, and gentian violet have been shown to be carcinogenic based on long-term exposure studies in lab animals. Residues of fluoroquinolones may increase antibiotic resistance to this class of antibiotics. These drugs had been used to treat the seafood to inhibit growth of bacteria and fungi or to prevent or treat parasitic infestation. However, they are not approved for use in farm-raised seafood in the U.S. As a result of these findings, in June 2007, the FDA restricted imports of five types of farmed seafood (catfish, basa, shrimp, dace, and eel) from China because of concerns regarding the unapproved drug residues. Lead-based and other heavy metal-based inks used for labeling candy wrappers have historically been a regulatory issue. The history of lead contamination is elucidated in Michael Kashtock’s chapter “Lead in Food: The Neo-classical contaminant.” Although the U.S. and EU have banned the use of heavy metal-based inks in food wrappers, lead has been found in the wrappers of candy imported from Mexico. Lead-based inks have been found on both the exterior and interior surfaces. If lead derived from a lead-based printing ink is found on the portion of the package that directly contacts the food or, if the lead is expected to migrate into the packaged food, the product would likely be regarded as being in violation of the Federal Food, Drug, and Cosmetic Act. Also, certain ingredients such as chili powder and certain types of salt, often
Al-Taher et al.; Intentional and Unintentional Contaminants in Food and Feed ACS Symposium Series; American Chemical Society: Washington, DC, 2009.
Downloaded by 80.82.77.83 on May 23, 2018 | https://pubs.acs.org Publication Date: December 17, 2009 | doi: 10.1021/bk-2009-1020.ch001
4 used in Mexican candy products may contain lead and these are an avoidable source of lead in the food supply. In 2006, FDA issued updated guidance regarding lead with the express purpose of lowering children’s exposure to small traces of lead present in certain candies. This occurred after testing and finding that certain types of Mexican candy products showed levels of lead above 0.5 ppm. FDA has reduced the allowable level of lead in candy to 0.1 ppm. In 2007, pet food manufacturers recalled more than 150 brands of dog and cat food contaminated with melamine, amelide, amiline, and/or cyanuric acid. Animals consuming the food developed symptoms of kidney failure, including loss of appetite, vomiting, lethargy, frequent urination, increased thirst and in some cases, ultimately death. At the exposure levels experienced by the affected cats and dogs, melamine, in combination with amelide, amiline, and/or cyanuric acid appears toform highly insoluble crystals in the animal’s kidney systems, resulting in kidney damage. A chapter on the “Renal toxicity of pet foods contaminated with melamine and related compounds” discusses the implications. The pet foods contained wheat gluten and rice protein as sources of protein for the animals diets. The wheat gluten and rice protein contained melamine, amelide, amiline, and/or cyanuric acid.. The Chinese suppliers had added these compounds to the pet food to increase the measured level of protein. These adulterants are high in nitrogen on a weight/weight basis, and artificially provide elevated protein levels when the wheat gluten/rice protein samples are analyzed by conventional methodology. Subsequently, it was discovered that manufacturers of pet foods convert the scrap and rework of the dog and cat foods into food for hogs, chickens, and fish. This low levels of melamine were also present in food given to hogs, chicken, and fish. The US FDA’s Forensic Chemistry Center first detected and identified the melamine adulterant in pet food. The Center made a preliminary identification of the melamine using a mass spectrometric technique that relies on an open-air ionization method known as direct analysis in real time (DART). The group further confirmed the finding with additional DART analysis coupled with GCMS analysis. The DART technique has the advantage of being more rapid than traditional GC-MS primarily because it requires no sample preparation, however, the instrumentation is not widely available. China has recently reacted to international pressure by agreeing to tighten food safety standards. In December 2007, the United States and China signed an agreement to place new registration and inspection requirements on 10 food products exported by Chinese companies. These products include some preserved foods, pet foods, and farm-raised fish, all of which have been found to be contaminated in the past. A major concern with regard to food safety is that the U.S. food supply might be vulnerable to attack. The U.S. FDA has worked with Sandia National Laboratories to develop a tool for defending the food production systems. “CARVER + Shock: Risk Assessment Tool” shows how this food-defense software can be used to increase protection of the food supply. To further enhance consumers safety with regard to contaminants, FDA developed the FDA Food Protection Plan which was made public in November 2007. This tool is designed to address both unintentional and deliberate
Al-Taher et al.; Intentional and Unintentional Contaminants in Food and Feed ACS Symposium Series; American Chemical Society: Washington, DC, 2009.
Downloaded by 80.82.77.83 on May 23, 2018 | https://pubs.acs.org Publication Date: December 17, 2009 | doi: 10.1021/bk-2009-1020.ch001
5 contamination of the nation’s food supply. The Food Protection Plan proposes the use of science and a risk-based approach to ensure the safety of domestic and imported foods eaten by American consumers. This plan implements a strategy of prevention, intervention and response to build safety into every step of the food supply chain. The Food Protection Plan, which focuses on both domestic and imported food, complements the Presidential Initiative: Import Safety Action Plan that recommends how the U.S. can improve the safety of all imported products. It is estimated that $2 trillion worth of goods were imported into the U.S. in 2007, and it is expected that will increase to over $6 trillion by 2015. The Import Safety Action Plan lays out a road map with short- and longterm recommendations to increase product safety at every step of the import life cycle. Together, these plans will improve efforts by the public and private sectors to enhance the safety of wide array of products used by American consumers. The plan is based on preventing harm before it can occur, intervening at key points in the food production system, and responding immediately when problems are identified. These efforts will provide a food protection framework that ensures that the U.S. food supply remains safe.
Al-Taher et al.; Intentional and Unintentional Contaminants in Food and Feed ACS Symposium Series; American Chemical Society: Washington, DC, 2009.
