Daily bioaccessible levels of selected essential but toxic heavy metals from the consumption of non-dietary food sources.

ABSTRACT

Researchers and regulatory bodies tend to focus on non-essential toxic elements when testing for inorganic chemical pollutants in food. Both toxic and essential elements are increasingly getting into the food chain from the extensive use agrochemicals and the use of contaminated water, raw sewage and untreated industrial effluent to irrigate crops. A holistic testing protocol for chemical contaminants in food should be the norm in order to protect human health, especially considering that the essential elements are as a matter of fact essential poisons. They are essential but are toxic above certain thresholds. Eating contaminated foods that are not considered to be dietary sources of the essential poisons may result in an inadvertent overdose, especially considering that consumers may be taking food supplements that recommended as sources of the essential elements. We measured the levels of manganese and zinc in rice and calculated the daily bioaccessible levels of the two elements. The daily bioaccessible levels were significantly higher than the recommended daily intakes in most of the samples. It has to be noted that exposure from various sources is additive, therefore, lower levels than recommended limits in one source may not guarantee safety from a particular chemical toxicant.