REPOSITORY > RESULTS

Abstract

Mercury (Hg) is one of the most toxic metals. Its toxicity depends on the route of exposure, on its chemical form and the dose to which a person is exposed. The most susceptible population are pregnant women and children. Epidemiological studies suggest neuropsychological dysfunctions in children who were prenatally exposed to monomethyl mercury (MeHg). Even at low levels of MeHg exposure subtle neurobehavioural deficits were observed. The general population is mainly exposed to MeHg by fish consumption and other seafood. Therefore, our aim was to assess the Hg exposure of the most susceptible Slovenian population of pregnant women and their foetuses through fish consumption. Hg and its species were determined in fish and other seafood consumed by the population involved in this study. Data on the frequency of fish consumption and the number of amalgam fillings obtained by questionnaires were used. Exposure was also assessed through different biomarkers of exposure such as total mercury (THg) and MeHg determined in hair, cord blood and breast milk. In addition, selenium (Se) and arsenic (As) levels were determined in the same biological samples as THg and MeHg, because seafood can represent a common source of exposure. Furthermore, Se can affect the bioavailability of Hg. In addition, our aim was to assess the Hg exposure of the population living in a specific contaminated area (Idrija mercury mine area) through consumption of local food items. This study was mainly part of the prospective cohort study of the EU FP7 PHIME project, which includes 4 recruitment areas in Italy, Slovenia, Croatia and Greece involving together 2202 pregnant women. Compared to pregnant women from Italy (n=900), Croatia (n=234) and Greece (n= 484), Slovenian pregnant women (n=584) have the lowest MeHg exposure levels, due to their low fish consumption. Moreover, most fish consumed by these women are probably farmed ones with lower levels of Hg than those from wild fisheries. At these low levels of exposure a number of factors can influence the strength of the correlation obtained between biomarkers of exposure and intake of MeHg through fish consumption. These important factors are the accuracy of the data contained in the questionnaire, the high variability of MeHg in fish, the presence of inorganic mercury from sources other than fish and intraindividual differences. THg and MeHg determined in cord blood or THg determined in hair are suitable biomarkers for MeHg exposure. Based on our results, it was concluded that THg level in hair is the most appropriate biomarker for exposure assessment for large epidemiological studies, because of the simple and practical collection and storage of the samples, and the relatively simple, fast and precise analytical determination of THg in hair and its relatively high concentration. Significant linear correlations were found between log transformed levels of Hg and Se, As and Se, and As and Hg in cord blood, mother’s blood and breast milk. In addition, significant correlations were found between the frequency of fish consumption and various biomarkers of exposure. Therefore, fish consumption, the possible common source of As, Hg and Se exposure, could explain the correlations between the elements determined in cord blood, mother’s blood or breast milk. While in general Hg levels in foodstuffs are much lower compared to levels in fish, levels of Hg in food from the contaminated site of the Idrija mine area are elevated. Moreover, the levels of Hg in vegetables, mushrooms, fish and deer have not diminished significantly during the past years, in spite of closure of the mine. In addition, up to 10 times higher levels of MeHg in some vegetables were found compared to those previously determined in earlier studies. However, the exposure levels assessed through biomarkers of exposure in this area during pregnancy were on the level of the population that live sin uncontaminated area.