**Potential Exposure and Risk Associated with Metal Contamination in Foods**

Luciana M. Coelho, Diego R. Pessoa, Kênia M. Oliveira, Priscila A.R. de Sousa, Lícia A. da Silva and Nívia M.M. Coelho

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/62683

#### **Abstract**

Humans require several trace elements as components of the diet. Some of these elements are required in extremely small quantities (only micrograms per day). On the other hand, in higher concentrations, some elements may also have deleterious, even lethal, effects. Metals such as arsenic, chromium (Cr), lead (Pb), and mercury (Hg) are naturally occur‐ ring chemical compounds. The contamination of food with these metals occurs mainly through human activities, such as farming and industry, or from contamination during food processing and storage. People can be exposed to these metals by ingesting contami‐ nated food or water, and their accumulation in the body can lead to harmful effects over time. The main objective of this chapter is to provide a literature review on the various types of foodborne poisoning caused by the contamination of food with arsenic, Cr, Pb, and Hg and on food safety issues associated with the presence of these metals in food. Research findings from various studies carried out to examine the relationship between metal exposure and the adverse health effects of metals are addressed.

**Keywords:** Diseases, chemical contamination, metals, food

### **1. Introduction**

Foods can be contaminated with harmful chemicals and microorganisms, which can cause illness in humans. Chemical contaminants can be classified according to the source of con‐ tamination and the mechanism by which they enter the food product. In the case of metal residues in food, contamination mostly occurs during food processing and storage [1].

In human nutrition, metals are well recognized by public health agencies, nutritionists, and researchers from various areas of knowledge. Humans require several metals as components

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

of their diet. Some of the metals are required in extremely small quantities, while some, such as arsenic, chromium (Cr), lead (Pb), and mercury (Hg), in certain amounts can adversely affect the nervous system, kidneys, and other vital organs of the body, which can be life threatening in extreme cases.

Ingeneral, sources of contaminationare contaminatedfoodandbeverages andpackaging [1, 2].

Metals can often be inadvertently and unintentionally introduced into food products. If these contaminants are not detected, they can become a major safety hazard for consumers. Metals such as arsenic, Cr, Pb, and Hg exist as naturally occurring chemical compounds. These metals are of particular concern in food because of their toxicity, especially in the case of long-term (chronic) intake, because they can accumulate in the body and cause organ damage particularly in susceptible groups, such as children [2].

Arsenic may be present as a contaminant in many foods, such as grains, fruits, and vegetables, where the metal is present because it is absorbed in the plant through the soil and water, and also trace amounts of arsenic can enter the food chain through the application of agricultural chemicals like fertilizers, which may contain arsenic. While most crops do not readily take up much arsenic from the ground, rice is different because it takes up arsenic from soil and water more readily than other grains. Also, arsenic exposure occurs through the consumption of aquatic food, especially shellfish and animals that feed from the bottom of the sea [3].

Cr exposure occurs mainly through the diet. Food crops that are polluted through contami‐ nated soil or water may contain high concentrations of this metal.

Pb is a toxic substance present in the environment in small amounts, and everyone is exposed to some Pb from daily actions such as inhaling dust, eating food, or drinking water. Tobacco smoking and the use of leaded petrol in vehicles are reported to be major sources of Pb exposure, although the Pb content in petrol has dramatically declined over recent decades, thereby reducing environmental exposure [3].

Hg exposure can occur through dental fillings that contain Hg compounds, occupational exposure, and herbal medicines. However, to date no studies have been able to show an association between amalgam fillings and ill health. Most dietary exposure is in the form of inorganic Hg. However, some fish may bioaccumulate the more toxic organic form, methyl‐ mercury, in significant quantities. Thus, diets rich in fish can be a cause of organic Hg exposure [3].

Thus, these metallic contaminants have been evaluated by international authorities, and safe reference values have been established. The maximum concentrations of these contaminants allowed by legislation are often well below toxicological tolerance levels, because such levels can often be reasonably achieved by using good food manufacturing practices. Even so, food contaminant testing is needed to assure the safety and quality of food products. Chemical analysis can be very useful in the food industry, with the development of new techniques to accurately and precisely quantify metals present in low concentrations in foods. These data can be applied in the area of toxicology to prevent diseases through prior diagnosis.
