Environmental contaminants are substances that, when accidentally or deliberately introduced into the environment, may have the potential to harm people, wildlife and plants. Contaminants include both naturally occurring chemicals released in unnaturally high concentrations, and chemicals that are novel to natural environments, produced by human activity and released either intentionally or accidentally.
Toxicology is the science devoted to understanding the impact of these chemicals on plant and animal (including human) individuals and populations. Understanding adverse effects of chemical contaminants leads to improved regulation, management and control of potentially toxic chemicals.
 Environmental Contamination of Food
Environmental contaminants in food fall into three categories—synthetic or natural organic chemicals, metals or their organic and inorganic derivatives, and natural or synthetic radioactive substances. Unlike food additives, environmental contaminants inadvertently find their way into the human food supply. They can enter food directly or indirectly as a result of such human activities as agriculture, mining, industrial operations, or energy production.
Environmental contaminants include substances from natural sources or from industry and agriculture. Many of the naturally occurring contaminants in food are of microbiological origin and consist of harmful bacteria, bacterial toxins, and fungal toxins.(Aflatoxin, a contaminant of peanuts and grains, is an example of a fungal toxin or mycotoxin.) The second category of environmental contaminants includes organic chemicals, metals and their complexes, and radionuclides. Only those environmental contaminants introduced into food as a result of human activities such as agriculture, mining, and industry are considered in this assessment. The environmental contamination of food is a result of our modern, high-technology society. We produce and consume large volumes of a wide variety of substances, some of which are toxic.It is estimated that 70,000 chemicals may currently be in commercial production in the United States and that 50 of these chemicals are manufactured in quantities greater than 1.3 billion lbs per year.
Environmental contamination of food takes two forms: long-term, low-level contamination resulting from gradual diffusion of persistent
chemicals through the environment, and relatively shorter term, higher level contamination stemming from industrial accidents and waste disposal.
 Health Impacts
Four factors determine whether and how seriously the environmental contamination of food will affect human health: the toxicity of the contaminant, the amount of the substance in the food, the amount of the contaminated food eaten and the physiological vulnerability of the individual or individuals consuming the food. The clinically obvious harmful health effects of radiation are usually associated with massive, high-level exposures. Past cases of radioactive contaminated foods have involved relatively small amounts of radioactive substances with low dose rates. Generally, the young are most sensitive to radiation exposure.
 Economic Impacts
The economic impact of an incident involving the environmental contamination of food includes the cost of condemned food, health costs, and the corresponding distributional effects and costs. The magnitude of the economic impact is determined by:
- The amount of food contaminated,
- The concentration of the contaminant in food,
- The chemical and toxicological characteristics of the contaminant, and
- The corresponding regulatory action taken on the contaminated food.