Heavy metals, sources of food contamination and toxicity

Heavy metals are toxic, non-biodegradable substances able to enter the food chain throughcontamination of plant, water and environment. Some mineral elements such as Pb, Hg, Cd andAs, are not suitable for biological functions and are positively toxic. Others, including Iron (Fe),Zinc (Zn), Nickel (Ni), and Copper (Cu) may play an essential role in human health, they canbe categorized as heavy metals when they are found in food commodities beyond certain limits(Valko et al., ۲۰۰۵). Therefore, exposures to heavy metals through dietary intake have beenidentified as a public health concern by the U.S. Food and Drug Administration (FDA). Heavymetals may enter human body through the inhalation of air pollutants, consumption ofcontaminated drinking water, exposure to contaminated soils or industrial waste, and Ingestionof contaminated food. Water may be contaminated by heavy metals through sources including,Natural sources, Anthropogenic sources, Domestic sewage, Industrial source, Urbanization,Agriculture source, Atmospheric source, Mining source. Crop contamination by heavy metalsis related to some factors such as: Soil temperature, pH, organic matter, texture,microorganisms, cation exchange capacity, and presence of other metals, metals mobility, planttype, and transpiration rates. Different kind of food such as rice, wheat, vegetables (such aslettuce, potato, tomato, onion and so on), fruits, candy, spices, meat, fish, egg, and milk anddairy products are susceptible to heavy metals contamination. There are a lot reports abouttoxicity of heavy metals. Heavy metals cause serious impacts on human and animal healthincluding reduced growth and development, cancer, organ damage, nervous system damage,and in extreme cases they may cause death. The focus of the current paper was to presentinformation about heavy metals sources, toxicity, exposure in food and water, and legislation.Regarding the adverse effect of heavy metals, monitoring of heavy metals in soil, water anddifferent kind of food is necessary. Moreover, application of different remediation techniquesis necessity to reduce the toxic heavy metals pathway to the food chain and human body.

کلیدواژه ها:

Food chain ، Heavy metals ، Human contamination ، Toxicity ، Water