Occurrence of trace metals in foodstuffs and their health impact

Background: Unlike organic pollutants, heavy metals are not created nor are biodegradable materials. They naturally occur in earth crust and many of them reach the environment via anthropogenic activities, which belonged to mining, smelting, production of fertilizers, pesticide applications and others. Scope and approach: Due to their water solubility and bioaccumulative tendency in different matrices of the environment, some heavy metals are extremely toxic even at low exposure levels and can be transported into the food chain. Key findings and conclusions: Many criteria are defined to identify heavy metals based on their specific gravity, weight and atomic number, chemical properties and their toxicity, therefore the heavy metals term is still very loose. Dietary exposure is a significant route for trace metals to the humans and constitutes about 90% of exposure. Long term exposure to metals via food consumption, drinking water or other occupational sources leads to serious problems, e.g., hepatotoxicity, kidney failure and neurotoxicity. Analysis of the current situation concluded that the concentrations of heavy metals declined over the years, but they are still hot spots suffering from domestic wastes, agrochemicals like pesticides, fertilizers and industrial wastes. Due to the contamination sources in those hot spots, levels of some metals exceeded the approved permissible limits and become sources of severe problems to humans. Almost comprehensive hazard assessment of these metals is missing due to insufficient data corresponding to body burden for groups potentially exposed to high concentration of metals and their concentrations in foodstuffs.