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“Food contamination” is an expression that means many things to many different groups of people. Whether it refers to the undesired presence of microorganisms, heavy metals, pesticides, or any other forms of “natural” or “man-made” compounds, one could simply define a food contaminant as a chemical or biological agent present in food that may be detrimental to the health of consumers exposed to them.
Many chemical food contaminants (pesticides, for example) are regulated in the U.S., with very clear limits that must be monitored and followed. American regulatory agencies, such as the U.S. FDA, the USDA, and the U.S. EPA have established limits of exposure for known contaminants to safeguard consumers. These limits are set at levels that will not put the health of consumers at an undue risk.
The issue becomes complex when the link between exposure and any potential impact on public health is not clearly established, and hence no limits are set even when such contaminants can be found in food. Hexabromocyclododecane, popularly known as a HBCD, for instance, is a flame retardant commonly used in many non-food items (such as thermal insulation and electrical equipment), which is not regulated in food, but can be found in numerous food items, possibly from leakage into water. It is considered a “persistent chemical,” which means it accumulates over time in the fatty tissue of animals that have been exposed (including humans). The consumption of low levels of HBCD is not known to cause any hazard for humans. However, it has been found to be highly toxic to aquatic organisms and there is little evidence on the effects of its accumulation in the human body when consumed in food. Therefore, it is complicated to establish levels of “safe” exposure.
Traditional classes of contaminants in food ingredients are naturally-occurring contaminants (e.g. heavy metals from soil) and man-made materials (e.g. pesticides). Where there is a reasonable expectation of the presence of contaminants in a specific food item, regulatory agencies have established appropriate limits, but not all contaminants can possibly be regulated in all food matrices. Arsenic is a commonly used illustration. As many heavy metals, arsenic exists in organic and inorganic forms, with the inorganic form being a higher health risk to humans than the organic form, and the U.S. FDA monitors the level of arsenic in different types of foods accordingly. One of the foods where arsenic levels are monitored is rice, where the plant takes up diverse forms of this metalloid element from the soil and the water where it grows, making arsenic levels in rice and rice products expectedly higher. On the other hand, arsenic in apple juice is not typically found in quantities that would cause any public health concerns, and it was not until samples of apple and grape juice showed limits above what the FDA considers safe, that attention was dedicated to this food product in particular. Today, arsenic levels in foods are monitored on a case-by-case basis, with special attention to foods that are consumed by children.
In general, contaminants are regulated based on the highest intake observed, taking into consideration the whole diet of individuals of a certain age and living in certain regions. Food toxicologists are much more concerned about the total exposure of consumers to a certain contaminant and, thus, always consider the whole diet of populations, including water consumption. The limits are usually set based on reports of food consumption that reflect the eating habits of certain populations and the exposure risk for each food group. Some food groups may contain a higher level of contaminants but are much less consumed than other groups with lower levels of that contaminant with high consumption rates. It is a very complex task to establish limits for contaminants in foods, when it comes to heavy metals and pesticides, for example.