Food contamination makes the food inedible. It can cause severe illness when such contaminated food is consumed by humans. Food contamination refers to foods that are spoiled or tainted because they either contain microorganisms, such as bacteria or parasites, or toxic substances that make them unfit for consumption. Contamination can be due to three main factors – biological, chemical or due to physical contamination. Biological contamination occurs due to bacteria, parasites, viruses. Chemical contamination is mainly due to cleaners, sanitizers, additives etc. Glass or metal particles in food can cause immense harm to the human body and if such type of particles is found in human body, it is called physical contamination. Four metals, namely lead, arsenic, cadmium and mercury, are of particular concern in food because of their toxicity. These may accumulate in the body and cause organ damage particularly to groups such as young children or older people.

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. Chemicals contaminate foods through different routes depending on the chemical and its physical properties, its use, and the source or mechanism of contamination. 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. Environmental contaminants that can enter the food supply chain include pesticides, heavy metals, and other chemical agents.