Module 4: Food Safety

Overview of Foodborne Illnesses

Foodborne diseases are defined as diseases associated with the ingestion of contaminated food.(1) Each year, foodborne illnesses cause 1 in 6 Americans (or 48 million Americans) to get sick, 128,000 to be hospitalized, and 3,000 to die.(2) The World Health Organization (WHO) estimates that each year 60 million people, almost 1 in 10 people in the world, become ill after eating contaminated food and 420,000 die. Children under 5 years of age carry the highest burden of foodborne disease accounting for 125,000 deaths each year.(3) The World Health Organization (WHO) lists the major concerns for food safety:

• Microbiological hazards: microorganisms transmitted through food. Examples include salmonella, campylobacter, and Escherichia coli.

• Chemical hazards: chemical contaminants carried in food. Examples include natural toxicants (such as mycotoxins and marine toxins), environmental contaminants (such as mercury and lead), and natural chemicals found in plants.

• New technologies: technologies implemented to improve food safety and production. Examples include genetic engineering, irradiation of food, and modified-atmosphere packaging.

Microbiological Hazards

The WHO reports that diarrheal diseases are the most common illnesses resulting from the consumption of contaminated food, and are estimated to cause 550 million people to fall ill and 230,000 deaths every year.(4)

There are 31 foodborne pathogens known today. The majority (80%) of foodborne illnesses are due to unspecified agents. The leading causes (among known pathogens) of foodborne illness include:

• Nontyphoidal salmonella, toxoplasma, listeria, norovirus, and campylobacter (responsible for the most deaths)

• Nontyphoidal salmonella, norovirus, campylobacter, toxoplasma, and E.coli (responsible for the most hospitalizations)

• Norovirus, nontyphoidal salmonella, clostridium, campylobacter, and staphylococcus (responsible for most cases of illness)(5)

Although norovirus usually only causes mild illness, it is the leading cause of foodborne illness because it affects so many people. Norovirus is highly contagious and can infect anyone. An individual can become infected with norovirus multiple times. This virus is the most common cause of gastroenteritis in the United States.(6)  

Table of Common Foodborne Pathogens(7)

[INSERT TABLE HERE]

Estimated annual number of domestically acquired foodborne illnesses, hospitalizations, and deaths due to 31 pathogens and unspecified agents transmitted through food in the United States(8)

Top five pathogens contributing to domestically acquired foodborne illnesses(9)

Incidence of foodborne illnesses has increased in recent years, likely due to a variety of factors. First, changes in farm practices and a higher demand for meat and poultry increase the risk of foodborne illness. Additionally, extensive and interconnected food distribution systems facilitate the contamination of feed products. Furthermore, intensive animal husbandry techniques currently employed have triggered the emergence of new zoonotic diseases.

Chemical Hazards

Chemical toxins can be found in foods that contain natural toxicants, including mycotoxins (produced by microfungi). Mycoses are diseases caused by the growth of fungi on animal hosts, while mycotoxicoses are those caused by dietary, respiratory, or dermal exposure to toxic fungal metabolies. Mycoses range from the relatively mild athlete’s foot to the lethal aspergillosis, and can be acquired via inhalation of spores or from a growth on the skin or gastrointestinal tract. Most mycotoxicoses, on the other hand, result from eating contaminated food.(10)

Furthermore, environmental toxins, such as mercury and lead, can have dangerous health consequences when ingested. Today, mercury poisoning is generally caused by the consumption of fish. Mercury poisoning can lead to many neural diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease. Lead, another heavy metal, can also interfere with the nervous system, as well as with the heart, bones, intestines, kidneys, and reproductive system.(11) Lead can enter the body through multiple routes, including inhaling lead dust in the air, ingesting lead paint, and drinking contaminated water. No amount of lead in the body is safe.

The FDA also regulates the following chemical toxins:

• Acrylamide: forms when asparagine (an amino acid) reacts with reducing sugars (e.g. fructose or glucose). This reaction usually occurs at elevated temperatures, such as when frying or baking, and in low-moisture conditions. Acrylamide is commonly found in plant-based foods, including potato products (French fries, potato chips), cereals (cookies, breakfast cereals), toasted bread, and coffee. Acrylamide has been found to be carcinogenic in rodents, and thus potentially carcinogenic in humans.(12)

• Dioxins and PCBs: dioxins (and dioxin-like compounds, DLCs) break down in the environment, and concentrate at high levels in livestock, fish, and shellfish. Studies show that DLC exposure can lead to many adverse health effects, including reproductive and developmental problems, cardiovascular disease, diabetes, and cancer.(13)

• Ethyl carbamate (urethane): found in fermented foods and beverages. Ethyl carbamate is potentially carcinogenic when administered in high doses on rodents.(14)

• Furan: produces other chemicals. Furan is also a potential carcinogen.(15)

• Melamine: used in the manufacture of dishes, plastic resins, flame-retardant fibers, components of paper, and industrial coatings. Melamine use in direct connection to human food production is not permitted in the United States. In high doses, melamine may cause kidney stones, as was observed in the 2008 outbreak of melamine in infant formula manufactured in China.(16)

• Perchlorate: can be naturally occurring or synthetic. Perchlorate, at high doses, affects the thyroid gland. Perchlorate is found in some public drinking water systems and foods.

• Radionuclides: naturally occurring or synthetic radioactive substances. When deposited in the body, radionuclides emit electromagnetic radiation, which can damage DNA and cause cancer.

New Technologies

Genetically modified organisms (GMOs) are organisms whose DNA has been altered through genetic engineering. Genetically modified organisms and foods were originally developed to improve crop resistance to plant diseases.(17) For example, plants that have the gene for toxin production by the bacterium Bacillus thuringiensis (BT) require lower quantities of insecticide spray. This BT toxin is safe for human consumption. Today, organisms are modified for more traits, including pest resistance, herbicide tolerance (so that weeds die but GMO crops do not), disease resistance, cold tolerance, drought tolerance, and higher nutrient levels. Rice illustrates one attempt to use genetic engineering to increase nutritional benefit. A staple food for many nations, rice does not contain many nutrients. Researchers have created a “golden” strain of rice that contains a high amount of beta-carotene (vitamin A).(18) Therefore, proponents of GMOs argue that GM foods may be the key to alleviating malnutrition and increasing food security.

GM foods traded internationally have passed risk assessments, and are thus generally safe to consume. GM foods must pass Codex Alimentarius standards (or the Codex system), which are food standards set by a joint FAO/WHO body. The Codex system was implemented in 1963, and deals with all government-regulated characteristics of certain commodities. Furthermore, the Cartagena Protocol on Biosafety (CPB) is an environmental treaty that regulates transboundary movements of living GMOs.

Debates on the health effects of GM foods are primarily concerned with allergenicity. Many children have allergies to multiple foods, and experts worry that introducing a gene into a plant or animal may introduce a new allergen or cause allergic reactions. To avoid allergic outbreaks, extensive testing is required before selling GM foods on the market. While there are other worries about more possible health detriments of GM foods, current evidence does not suggest any other health concerns.(19)

Footnotes

(1) WHO Department of Food Safety, Zoonoses and Foodborne Diseases Sustainable Development and Healthy Environments. WHO Consultation to Develop a Strategy to Estimate the Global Burden of Foodborne Diseases. France: WHO, 2006. Print.

(2) CDC. "Burden of  Foodborne Illness in the United States." (July 15, 2016)  https://www.cdc.gov/foodborneburden/burden/index.html.

(3) WHO. "Food Safety." (October 31, 2017) http://www.who.int/news-room/fact-sheets/detail/food-safety.

(4) Ibid.

(5) CDC. "Burden of  Foodborne Illness in the United States." (July 15, 2016)  https://www.cdc.gov/foodborneburden/burden/index.html.

(6) CDC. "Norovirus." https://www.cdc.gov/norovirus/ (July 16, 2018).

(7) USDA Food Safety and Inspection Service. "Common Foodborne Pathogens." https://bit.ly/2p8UUok.

(8)  CDC. "Burden of  Foodborne Illness in the United States." (July 15, 2016)  https://www.cdc.gov/foodborneburden/burden/index.html.

(9) Ibid.

(10) Bennett JW, & Klich M. “Mycotoxins.” Clinical Microbiology Review. 2003;16:497–516.

(11) Mayo Clinic Staff. "Lead Poisoning." (December 6, 2016) https://www.mayoclinic.org/diseases-conditions/lead-poisoning/symptoms-causes/syc-20354717. Mayo Foundation for Medical Education and Research.

(12) Robin, L. Acrylamide, Furan, and the FDA. Rep. Ed. Sebastian Cianci. Target Group, 2007. Print.

(13) FDA. "Dioxin Analysis Results/Exposure Estimates." (November 2007) https://www.fda.gov/food/foodborneillnesscontaminants/chemicalcontaminants/ucm077444.htm.

(14) FDA. "Ethyl Carbamate Preventative Action Manual." (December 12, 2017) https://www.fda.gov/food/foodborneillnesscontaminants/chemicalcontaminants/ucm078546.htm.

(15) Robin, L. Acrylamide, Furan, and the FDA. Rep. Ed. Sebastian Cianci. Target Group, 2007. Print.

(16) Food and Agriculture Organization of the United Nations. “Melamine.” (2018) http://www.fao.org/food/food-safety-quality/a-z-index/melamine/en/.

(17) WHO. "20 Questions on Genetically Modified Foods." (May 2014) http://www.who.int/foodsafety/areas_work/food-technology/faq-genetically-modified-food/en/.

(18) Whitman, D. "Genetically Modified Foods: Harmful or Helpful?" (2000) CSA Discovery Guides. 1-13.

(19) Ibid.