Environmental Contamination of Food Chapter II Environmental Contamination of Food Maintaining an adequate, safe food supply has been a major goal of the Fed- eral Government since 1906, when the first Federal food and drug law was signed into law. Historically, chemicals such as salt, sugar, and wood smoke have been used to preserve foods. Modern food technology relies extensively on the use of chemicals not only for preservation but also to produce appealing colors, flavors, aromas, and textures. Most developed countries now have food laws designed to permit the use of such chemicals in food under conditions judged to be safe. These chemicals are not considered adulterants or contaminants and are classed as intentional addi- tives. Other chemicals may enter food as a result of their use in food production, handling, or processing. Such substances maybe legally permitted if they are un- avoidable under good manufacturing practices and if the amounts involved are considered safe. These chemicals are classed as incidental additives. The pres- ence of both these classes of chemicals in food is controlled by regulation. Environmental contaminants include sub- chemicals (l). During the production, use, and stances from natural sources or from indus- disposal of these substances, there are oppor- try and agriculture. Many of the naturally oc- tunities for losses into the environment. For curring contaminants in food are of microbio- example, the Environmental Protection Agen- logical origin and consist of harmful bacteria, cy (EPA) estimates that there are more than bacterial toxins, and fungal toxins. (Aflatox- 30,000 chemical and radioactive waste dis- in, a contaminant of peanuts and grains, is an posal sites. Of these, 1,200 to 2,000 are con- example of a fungal toxin or mycotoxin. ) The sidered threats to human health (2). second category of environmental contami- Environmental contamination of food takes nants includes organic chemicals, metals and two forms: long-term, low-level contamination their complexes, and radionuclides. Only resulting from gradual diffusion of persistent those environmental contaminants intro- chemicals through the environment, and rela- duced into food as a result of human activities tively shorter term, higher level contamina- such as agriculture, mining, and industry are tion stemming from industrial accidents and considered in this assessment. waste disposal. The environmental contamination of food is An example of low-level contamination is a result of our modern, high-technology soci- polychlorinated biphenyls (PCBs). This group ety. We produce and consume large volumes of substances was widely used in transform- of a wide variety of substances, some of ers and capacitors, as heat-transfer fluids, which are toxic. It is estimated that 70,000 and as an additive in dyes, carbon paper, pes- chemicals may currently be in commercial ticides, and plastics (3). Although production production in the United States and that 50 of was halted in 1977, PCBs remain an ubiqui- these chemicals are manufactured in quanti- tous, low-level contaminant of many foods, es- ties greater than 1.3 billion lbs per year. pecially freshwater fish. Seven percent of this country’s gross national product (GNP), $113 billion per year, is gener- An example of the second type of contami- ated by the manufacture and distribution of nation is polybrominated biphenyls (PBBs) in 15 16 . Environmental Contaminants in Food dairy products and meat. PBBs, a fire retard- level contaminant in Michigan because they ant, were accidentally mixed into animal are very stable and resistant to decay. Ani- feed. Dairy cattle that were fed the contami- mals raised on farms affected by the original nated feed produced contaminated milk. The feed contamination are now contaminated by distinctions between the two types of food the PBB residues remaining in the pastures contamination are not exclusive. For exam- and farm buildings. pie, PBBs have now become a long-term, low- HOW FOOD BECOMES CONTAMINATED Chemicals contaminate foods through dif- gated railroad cars, trucks, ships, or storage ferent routes depending on the chemical and buildings used for transport or storage of its physical properties, its use, and the source human food and animal feed are also sources or mechanism of contamination. of environmental contamination. The interi- ors are sprayed or fumigated with pesticides, Organic substances that have contami- iand if not sufficiently aired, contamination of nated food have been either industrial or 1 the food or feed occurs. agricultural chemicals. Pesticides are the only agricultural chemicals known to be en- The manufacture of organic chemicals pro- vironmental contaminants in food (see tables duces sludges, gases, and liquid effluents of 1-3). A pesticide becomes an environmental varying chemical complexities. The usual contaminant when it is present in foods for ,waste disposal methods (sewage systems, in- which the application or use of the substance cineration, landfill) are unable to prevent or- has not been approved. Livestock, poultry, ganic residues from entering the environment and fish can be contaminated when applica- in spite of Federal laws and corresponding tion or manufacturing of pesticides occurs in regulations governing disposal. The routes in- the vicinity or when residues are transported clude the atmosphere, soil, and surface or through the environment. Improperly fumi- ground water. Table 1.— Reported Incidents of Food Contamination, 1968-78, by State and Class of Contaminant State Pesticide Mercury PCB PBB Other Total New York . • ., . 1 1 1 — — 3 Idaho. 1 2 — 3 South Carolina. — 1-biphenyl 1 Minnesota . — 1 — 1 Louisiana . 8 5 4 — 17 Colorado. 1 1 — 2 Georgia. 15 — — — 15 Maryland. — 1 — 2-petroleum 3 Texas . — 1 — 1 New Jersey. 2 1 — 1-ß-methoxy napthalene 4 and tetraline Kansas . — (I)* — — (l)* Missouri . 4 — — — — 4 New Mexico. — 1 — — — Alaska. (l)* — — — — (:)* California . 1 3 — — — 4 Indiana ., 3 well-documented — 1 — — 9 5 other incidents Michigan. 13 1 2 1 — 17 Virginia, ., ... 1 — — — — 1 Totals ... 56 19 8 1 4 88 “Several conservatively estimated as one SOURCE Of fLce of Technology Assessment Ch. //— Environmental Contamination of Food ● 17 Table 2.— Reported Incidents of Food Contamination, 1968-78, by State and Food Fruit/ Game/meat/ State Dairy Eggs Vegetable Fish/shellfish Grain poultry 3 — — 1 — 1 — 1 1 — 9 1 — — — — 3 — 1 — — 2 — — — 1 — — — — 1 2 — 1 — — 1 4 — 4 — — 1 — 27 3 8 Table 3.— Number of Incidents of Environmental Contaminants of Food Reported by Federal Agencies, 1968-78 Agency Pesticides Mercury PCB’s Other Food affected USDA/FSQS 39 — — — Chickens, turkeys. ducks. cattle, swine, lambs — 1 — — Swine — — 6 — Poultry — — — 1 (Phenol) Cattle FDA ... 21 — — — Fish. cheese, pasta — 84 — — Fish — — 3 — Fish, eggs, bakery products Total. 60 85 9 1 SOURCE Off Ice of Technology Assessment Metals can be released into the environ- operation of nuclear reactors and processing ment in several ways. The mining and refin- plants, and fallout from nuclear weapons ing processes produce dust and gases which tests. The primary route by which food be- enter the atmosphere. Metallic salts formed comes contaminated is the deposition of air- during recovery and refining processes can borne material on vegetation or soil. The sub- escape as waste products into surface and sequent fate of the radionuclide is deter- ground water. Sewage sludge used as fertiliz- mined by its chemical and physical nature er on agricultural land also poses a potential and whether it is absorbed and metabolized food contamination problem. Trace metals by plants or animals. Natural radioactivity present in the sludge can be taken up by may become a concern when ores containing crops grown on treated soil. Cadmium is the radioactive substances are mined and proc- trace metal in sludge that currently gener- essed. The products or wastes may concen- ates the greatest concern. trate the radionuclides. Examples of this are uranium tailings, phosphate rock waste, or Radioactivity in food stems from three slags from phosphorus production. Radium sources: natural radioactivity. releases from may enter the food chain when it dissolves in 18 . Environmental Contaminants in Food ground water and is taken up through plant summarizes the radionuclide contaminants of roots. significance for foods. Nuclear reactors normally release radio- Nuclear waste-processing plants could active noble gases that do not contaminate also have either gaseous or aqueous releases. foods. Reactors do contain large inventories In this case, the fission products are aged of fission products, transuranics, and other before processing, and iodine and the gas- activation products. Accidental releases can eous precursor radionuclides are not re- contaminate vegetation by deposition of parti- leased. Tritium and carbon-14 are the major cles on leaves and soil, or through water. Gas- airborne products, while the waterborne ra- eous releases would most likely involve the dionuclides are the same as for reactors. volatile elements such as iodine and tritium, or those with volatile precursors, such as Atmospheric nuclear weapons tests dis- strontium-90 and cesium-137. Aqueous re- tribute their fission products globally. Local leases would follow failure of the onsite ion deposition depends on the size of the weapon exchange cleanup system. Any of the water- and the conditions of firing (high altitude, sur- soluble elements could be involved. Table 4 face, or underground).