| Lead is one of the oldest heavy metals that have been utilized in many industrialareas. Lead has no beneficial physiological impact to human body. The ideal bloodlead level is zero. Long term exposure to lead will bring various adverse effects tohuman health, including neurotoxicity, hematotoxicity, renal toxicity, andreproductive toxicity.This research collects63rice samples from the main grain producing areas inChina. Having been hulled and whitened to get milled rice. After that, each part ofrice samples is grinded into powder by mill. Then they are labeled and packed,totaling126samples. Microwave digestion (MWD) and Isotope Dilution-InductivelyCoupled Plasma-Mass Spectroscopy (ID-ICP-MS) are applied in analyzing thesesamples as these methods are precise and with excellent recovery rate. The resultshave shown that lead removal rate is satisfactory after finishing，and lead pollution inpolished rice has significantly reduced. The average lead content in rice is0.141mg/Kg, while the average lead content in polished rice is0.050mg/Kg.In addition, this research also conducts sample survey on common foods in acertain area, including35rice samples,33rice powder samples,94vegetable samples,and75pig haslets. As a result of the same pre-processing and monitoring methods,12samples are detected having lead content higher than the regulated value. Most of theover-standard samples are gathered from farmer’s market. In addition, lead exceed thestandard rate of rice is highest in common foods, then is the pig offal and flour, andvegetable is the lowest.Based on lead pollution level of the samples, health risk analysis on polished riceand other common foods is conducted in accordance with the US EnvironmentalProtection Agency (EPA) standards and the Joint Expert Committee on FoodAdditives (JECFA) recommended provisional maximum tolerable daily intake. Theresults of both methods have shown that lead content level in polished rice andcommon foods does not form risk to body health. |
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