Exposure of the population of the Republic of Moldova to mercury and the ways of reducing health risk: Summary of the thesis of Doctor of Medical Sciences: 331.02 - Hygiene

Abstract

Research actuality and importance. According to the World Health Organization (WHO), exposure to mercury (Hg) even in very small amounts can cause severe effects on the population health or to foetus due to exposure of their mother’s during their pregnancy. Mercury affects the nervous, digestive, cardiovascular and immune systems [20, 42]. In the National Profile on sustainable management of chemicals in the Republic of Moldova (RM) from 2008 [2], Hg is set as a grade 1 priority at the national level, statement reconfirmed by a subsequent national report in 2012 [31]. The RM bears coherent and complex statistical data regarding Hg assessment or as a factor of the environmental pollution and population’s health impact [34, 35, 36, 37, 38, 45]. Between 2014-2017, the main sources of Hg pollution in the RM were identified. The Environmental Pollution Prevention Office under the Ministry of Environment has prepared the National inventory on mercury releases in the Republic of Moldova (IN) for the reference year 2014, the first national report in this regard. Was established that there are currently sources of Hg pollution in the country, being identified emissions of 972,12 kg Hg/year [33]. The RM has ratified the Minamata Convention (MC) recognizing that Hg is a chemical with worrying effects worldwide due to its long-distance transport capacity, persistence in the environment, bioaccumulation capacity in ecosystems and significant negative on human and environmental health [24]. At the same time, authorities become aware of the risks on vulnerable population’s health - women, children [26, 30, 42, 44]. Thus, the health authorities by articles 16 and 19 of the MC are obliged to inform, raise awareness and educate the population as well as to research, and to monitor the levels of Hg in the environmental elements, food products with the assessment of the impact on the population's health [24, 32, 37, 45]. For these reasons, the performed study is currently of a major importance for the public health policy, specifying the vital relevance of knowing the level of Hg in water, air, soil and food, especially in marine products, and setting the necessary recommendations. The study purpose: Mercury exposure assessment for the population of the Republic of Moldova for the elaboration of prevention measures appropriate to the appraised degree of risk. Objectives: 1. Identification of potential sources of mercury pollution. 2. Determination and analysis of mercury concentration in frequently consumed species of fish, crustaceans and molluscs (FCM). 3. Estimation and analysis of mercury concentration in air, water and soil. 4. Risk assessment for the exposure to mercury of the population and development of prevention measures appropriate to the degree of appraised risk. General methodology of scientific research. An ecological study was carried out using complementary descriptive, calculus and experimental methods to assess and estimate the impact of mercury (metallic form, methyl mercury) on the population health of the RM in compliance with scientific rigors, ethical principles of institutional, national and international research. The study object was considered general population and children from boarding schools aged 7-18y, kindergartens with 9,5-10h activity regime assuming that the respective category is aged 3-7y and children from nurseries with activity regime 9,5–10h, aged 1-3y. Daily intake for methyl - mercury and metallic mercury was calculated. We applied a toxicokinetic model to calculate the theoretical MeHg concentration in hair and blood. Using analytical laboratory tests the Hg concentration in various fish species, crustaceans and molluscs, in air, water and soil was investigated. 6 The novelty and scientific originality of the results obtained. For the first time, from a systemic perspective, was performed a complex multilateral study of the level of Hg pollution of the environment, toxico-hygienic aspects on the Estimated Daily Intake of Hg, metallic and organic form, by human body for the general population and children of the Republic of Moldova (RM) by applying different approaches. It has been scientifically argued which necessary measures should be taken by the public health service. The nationally recommended fish consumption (Daily Required Quantity) for children of different ages was analysed relating to the presence of Hg in FCM. The study was conducted by applying a new, justified, innovative methodology for the RM. The exposure level to Hg was identified for the RM population through water, air, soil, food (fish, crustaceans and molluscs) and the intentional use of Hg in devices. The peculiarities of the exposure to Hg for the general population (per capita) and children of different ages in the RM were calculated, characterized, analysed and scientifically proved for better understanding of the problem size at national level. The study aids to the development and optimization of public health strategies and prevention measures aimed at mitigating the impact of Hg on the public health. The research results magnify the theoretical basis part of estimated population's health associated risk as a result of exposure to Hg by ingestion of soil, water, air and FCM consumption. An original methodology was used, applicable for another future similar researches. The materials of the thesis can serve as methodological-didactic support in the university and postgraduate training of the medical staff, as well as for the preparation of the didactic materials (courses, guidelines) for the practitioners. The sources of Hg pollution were identified and characterized and their potential impact on the population's health was estimated, which created the possibility to argue, develop prophylactic measures specially to prevent exposure of children. The applicative value of the research. The study allows the development, planning of measures and recommendations for the state public health surveillance service in order to recognize and address the mercury as a public health issue. The results of the study will serve as support for the practical departments of the NAPH in honouring the obligations and responsibilities stated in articles 16, 18, 19, 20, 21 of the Law no. 51 of 30.03.2017 on the ratification of the MC on mercury. The results of the study allowed the elaboration of the guidance material "Guide on mercury incidents management: remedial options" for Central and Local Public Authorities, Preschool and School Institutions, Public Medical Institutions. Sharing and approval of research findings. The thesis was discussed, approved and recommended for defence at the joint meeting of the PhD supervisors, members of the guidance committee and the primary research unit (Scientific Laboratory of Chemical Dangers and Toxicology within NAPH) from 01.07.2021 (minutes no. 1), at the meeting of the Scientific Profile Seminar within Nicolae Testemitanu” State University of Medicine and Pharmacy of the Republic of Moldova on profile 331. Public Health, specialty Hygiene 331.02 of 17.09.2021 (minutes no. 1). Subsequently the thesis was recommended for public support by the decision of the Scientific Council of the Consortium from 02.12.2021 (No. 24). In order to carry out the study, the positive opinion of the Research Ethics Committee from 03.06.2016 no. 64 was granted. Published articles. The research results were published in 16 scientific papers, 5 as single author, 1 article in an international scientific journal, 4 in accredited national scientific journals, 5 articles in the papers of scientific conferences, and 5 participations at scientific forums.