Dietary Exposure to Heavy Metals and Radionuclides in Lebanon: A Total Diet Study Approach

Abstract

Total diet studies (TDSs) have been initiated in 2004 in Lebanon and have provided the first estimates of the dietary exposure of the population to heavy metals (lead, cadmium, and mercury) and to gamma-emitting radionuclides. The foods that made up the average “total diet” were derived from an individual food consumption survey of a representative sample of Lebanese adults living in Beirut, the capital. Food items constitutive of the “total diet” represented approximately 80 %, on a weight basis, of the daily ration of the average individual. The analytical quantification of heavy metals in food samples was performed using inductively coupled plasma mass spectrometry while the quantitative determination of radionuclides was performed using two gamma ray spectrometry systems. Dietary exposure assessment was performed using a deterministic model. The average dietary exposures to Pb and Cd represented 7 % and 17 %, respectively, of the appropriate PTWIs with the major dietary contributors being cereals, vegetables and potatoes as well as drinking water. Based on the analysis of fish samples, mean dietary exposure to methylmercury was found to represent 17.5 % of its PTWI. Cs-134 and I-131 were not detected in any of the analyzed food samples, while traces of Cs-137 were found in five samples. The TDS conducted in the country showed that the average consumer is not at risk of exceeding the toxicological reference values for heavy metals and provided reassuring data as to the radioactive contamination of foodstuffs in the country. The main output of this TDS, other than characterizing the risk for the consumer, is the fact that it has provided the framework for other total diet studies, which are currently ongoing in the country and which target the dietary exposure of the Lebanese consumer to pesticide residues, mycotoxins and essential minerals.