Toxins, Unnatural, and Food Safety

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TOXINS, UNNATURAL, AND FOOD SAFETY. Toxins may be released into the environment through industrial processes and agricultural products. These toxins are unnatural and may become harmful when they enter the food chain through crop and animal uptake.

Many agricultural products are known to contain heavy metals and other contaminants. In fact many, such as fertilizers, pesticides, fumigants, sludge, liming agents, animal feed supplements, and soil amendments, are known or are suspected to be derived from industrial waste. Waste disposed in this manner includes but is not limited to that generated by leather tanneries, steel mills, coal-fired power plants, mines, film processors, nuclear fuel processors, pulp and paper, tire incinerators, and petroleum refineries.

Little regulation and even less oversight is devoted to this method of disposal. If the waste contains just one of the macronutrients or micronutrients or if it possesses a soil-amending quality, industry can call it a product. Theoretically, anything can go into fertilizer. It is frequently contaminated with arsenic, mercury, cadmium, lead, dioxin, radionuclides, nickel, beryllium, and more. The only requirement for these wastes is that they meet the standard for disposal in a lined hazardous waste landfill. In other words, they are too toxic for standard disposal, but because of a loophole in the law, they are not too toxic for disposal on farmland. Even mined fertilizers, such as phosphate rock, may contain high levels of toxic metals.

Fertilizers, soil amendments, and liming materials are of particular concern since they are applied to agricultural soils in high volume. Over 110 billion pounds of fertilizer are land-applied each year in the United States, approximately 90 percent of it on farmland. The Environmental Protection Agency, whose charge it is to regulate hazardous waste disposal, admits that it does not know how much hazardous waste is disposed as fertilizer or the fate of these chemicals in the environment.

It is the fate of these chemicals that is cause for greatest concern. Increased soil concentrations, differing soil types, and pH levels can affect plant uptake of contaminants. Sandy soils and low pH, for example, increase plant uptake, while clay soils and high pH reduce it. Many of these contaminants have half-lives of hundreds of years and can change form in the environment as new chemicals are added. These new compounds may differ from the originals in toxicity, solubility, and plant availability.

In addition to crop uptake, these contaminants may also pollute waterways and become available for uptake by other plant and animal species. Forty percent of waterway pollution is attributed to runoff. Additionally, some of these wastes, such as zinc from steel mill flue dust, are used as animal feed supplements. Animals ingest thirteen toxic metals, which concentrate in organ meats, such as liver and kidney, and dioxin, which is stored in fat.

These toxins find their way into the food supply, as documented by the Food and Drug Administration (FDA) Total Diet Study. Since 1961 the Total Diet Study has monitored the U.S. food supply for industrial contaminants, toxic elements, radionuclides, essential minerals, and pesticides. The study has found that, on a body-weight basis, infants and toddlers consume on average two to three times as much cadmium, arsenic, and mercury and three to four times as much lead as do teens and adults.

Infants, toddlers, and developing fetuses are the most vulnerable populations. Many toxins pass from the mother to the fetus, potentially altering the developing brain, nervous system, and orderly development of the body.

See also Agronomy ; Crop Improvement ; Ecology and Food ; Food Safety ; Government Agencies ; Government Agencies, U.S. ; Health and Disease ; High-Technology Farming ; Inspection ; International Agencies ; Water: Safety of Water .


Agency for Toxic Substances and Disease Registry (ATSDR). "Toxicological Profiles for Heavy Metals." Available at

Gunderson, Ellis L. "FDA Total Diet Study." Journal of AOAC International 71, no. 6 (1988): 12041207; 78, no. 6 (1995): 13531363.

Raven, K. P., and R. H. Loeppert. "Trace Element Composition of Fertilizers and Soil Amendments." Journal of Environmental Quality 26 (1997): 551557.

U.S. Environmental Protection Agency. Background Report on Fertilizer Use, Contaminants, and Regulation. Washington, D.C.: National Program Chemicals Division, Office of Pollution Prevention and Toxics, U.S. Environmental Protection Agency, 1999.

Wilson, Duff. Fateful Harvest: The True Story of a Small Town, a Global Industry, and a Toxic Secret. 1st ed. New York: HarperCollins, 2001.

Patricia Martin

A Toxicity Glossary

Arsenic Known carcinogen. Highest concentrations are in seafood, rice and rice cereal, mushrooms, and poultry. Root crops, such as carrots, onions, and potatoes, are the most vulnerable.

Cadmium Low levels are found in all foods. Largest dietary contributors are grains and cereal products. Highest levels are found in leafy vegetables, potatoes, and other root crops. Long-term exposure to low levels may cause kidney disease, cancer, lung damage, and fragile bones.

Dioxin Endocrine disruptor. Causes birth defects, developmental problems, and cancer.

Lead Neurotoxin. Lowers IQ and damages the immune system. Fruits, grains, cereal products, and legumes contain the highest concentrations. Fetuses and pregnant women are most at risk.

Mercury Possible carcinogen. May cause brain, kidney, or fetal damage. Highest concentration is in fish. Grains and meat account for half of the dietary intake.

Macronutrients Examples include nitrogen, phosphorous, potassium, sulfur, calcium, magnesium.

Micronutrients Examples include boron, molybdenum, copper, manganese, zinc, selenium, iron chloride.