Food safety standards

Both the Codex Alimentarius and the EU use food safety standards to control trade of foods and animal feed. With regard to these standards there is a distinction between "contaminants" and "residues". Contaminants are regulated by means of a Maximum Level (ML), whereas standards for residues are called a Maximum Residue Level (MRL). Some of the MRLs and MLs of the Codex Alimentarius and the EU are maintained in public databases, whereas others are only published in pdf online.

Contaminants

The General Standard for Contaminants and Toxins in Food and Feed (CXS 1993-1995) of the Codex Alimentarius defines a contaminant as: "Any substance not intentionally added to food or feed for food producing animals, which is present in such food or feed as a result of the production (including operations carried out in crop husbandry, animal husbandry and veterinary medicine), manufacture, processing, preparation, treatment, packing, packaging, transport or holding of such food or feed, or as a result of environmental contamination". In the EU, Council Regulation (EEC) 315/93 uses similar lines.

Contaminants in food can be classified in different groups. First the environmental contaminants like the heavy metals and persistent organic pollutants (POPs) that are found in soil, surface waters, or groundwater, as a result of former use or from waste. Next are the "toxins". Well known are the mycotoxins that come from fungi growing on plants. These toxins are found in foods such as cereals, fruits, and nuts. There are also toxins in plants to protect them from being eaten. These are created by the plants themselves, and many of them are extremely toxic for humans and for agricultural animals. So, there are also MLs for toxins in animal feed. And finally the process contaminants, that are residues of chemical substances used in the food industry (such as mineral oils and fats), or substances that are unintentionally formed during processing (such as acrylamide that can be formed during baking foods). So, contaminants are chemical substances that are not intentionally added to food or feed, but can be found as a result of uncontrolled contamination.

Residues

In contrast, "residues" are intentionally added to food or feed. Obvious residues are food additives, like colorants, artificial flavors, and preservatives. And chemicals like stabilizers, emulsifiers, fortifiers, sweeteners, and glazing agents. Many of them have an E number in the EU. Less obvious residues are the pesticides and veterinary drugs. These chemical substances are used for the production of foods, following strict rules of how they are to be applied, and with maximum quantities to be sprayed or injected. Residual concentrations of pesticides and veterinary drugs will remain in the plants and animals, and can be detected in the foods that are derived from these plants and animals.

Regarding the pesticides it should be noted, that a small group of former (now obsolete) pesticides is considered to be contaminants. These pesticides, such as DDT, dieldrin, and endrin were widely used in the second half of the twentieth century, but later banned because of their persistent properties. Residual concentrations of former use can still be found in soil, making obsolete pesticides be environmental contaminants which affect food production.