CADMIUM, LEAD AND MERCURY CONTENTS IN FISHES – CASE STUDY

Journal of Microbiology, Biotechnology and Food Sciences Tóth et al. 2012 : 1 (February Special issue) 837-847 REGULAR ARTICLE CADMIUM, LEAD AND MERCURY CONTENTS IN FISHES – CASE STUDY Tomáš Tóth1,2* , Jaroslav Andreji3, Juraj Tóth1, Marek Slávik1, Július Árvay1, Radovan Stanovič1 Address: 1Slovak University of Agriculture in Nitra, Faculty of Biotechnology and Food Sciences, Department of Chemistry, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic 2 Institute of Chemistry, Center of excellence for white-green biotechnology, Slovak Academy of Sciences, Trieda A.Hlinku 2, 94976 Nitra, Slovak Republic 3 Slovak University of Agriculture in Nitra, Faculty of Agrobiology and Food Resources, Department of Poultry Science and Small Farm Animals, Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic *Corresponding author: ABSTRACT Fish meat is a perfect foodstuff which is up to standard of rational nourishment. It is source of healthy and good digestible material rich on proteins, minerals and vitamins. Fish muscles especially back and lateral muscles are the most important parts of fish organism consumed for escellent chemical composition. Proteins in fish meat are rich on high aminoacids content. The content of fish fat is usually low with the high proportion of unsaturated fatty acids. Also minerals and B, A and D vitamins are very important components of this foodstuff. According to rational nourishment the fish meat should be consumed minimal 2 times weekly. Our research was focused on analysis of bottomn sediments in water reservoir Kolinany from the aspect of Cd, Hg and Pb contents, the determination of observed heavy metal contents in different parts of carp body and the evaluation of hygienic status and suitability of fish meat for the human consumption. Our results have confirmed the hygienic wholesomeness of bottom sediments in water reservoir Kolinany. The Cd, Pb and Hg contents in sediments represent no risk of their input into the fish organisms. The Cd content in fish meat was lower than maximal available amount given by legislative norms, but in selected parts of fish organism such as skin, gills and fins the Cd 837 JMBFS / Tóth et al. 2012 : 1 (February Special issue) 837-847 hygienic limit is 2.9 – 6.6 times exceeded. The Pb content in fish meat was under the hygienic limit, however in skin, gills and fins the content of this heavy metal was 1.31- 2.64 higher than maximal legislative given value. Fish skin, gills and fins belong to the non cosumed parts of fish body by people. The Hg content in fish meat was also lower than hygienc limit. The highest Hg content was observed in fish muscles (0.0544 mg.kg-1) and the lowest one in fish gonads (0.0058 mg.kg-1). The results of Cd, Pb and Hg content determination in carp body confirmed that fish muscles belong to suitable foodstuffs for the human consumption. Keywords: cadmium, lead, mercury, fish, carp, food hygiene INTRODUCTION While in last decades the concentration of various toxic and risky elements in environment has increased due to man’s activities, it has caused the transfer of mentioned elements into food chain. Substantial issue is to monitor their entries into environment, especially in areas with highly developed industry (Toman et al., 2003). Almost all of metals occur naturally in surface and also in ground waters. Many of them are essential for life in trace amounts, but in higher concentrations could act negatively. Hygienically serious issue includes metals with toxic properties that rank among the most substantial inorganic contaminants of waters and soil (Dercová et al., 2005). Mainly lead, cadmium and mercury rank among toxic metals occurring in waters. One of the significant negative properties of these metals is their ability to cumulate in sediments. Especially mercury has great ability to accumulate in aquatic organisms. Mercury passes from water into bottom sediments in flowing waters and dams, where it accumulates mostly in the form of sulfhide. Content of mercury in bottom sediments is in relation to level of burden of key locality, but also to character of sediment. Bottom sediments could be as suitable indicators of contamination of surface waters by lead and cadmium. Samples of sediment with bulk of mud and organic parts have in most cases higher content of mercury in comparison to sample of sandy character (Cibulka et al., 1991). Remarkable cumulating ability of sediments poses a source of eventual contamination of fish meat by risky elements. The importance representation of fish in our diet has been proved by so-called Eskimo paradox. Diet of original inhabitants of Greenland – Eskimos has consisted only from products of animal kingdom. It comprises of fish and marine mammals, 838 JMBFS / Tóth et al. 2012 : 1 (February Special issue) 837-847 what means that it is very rich in animal proteins, lipids and cholesterol. It seemed almost incomprehensible why the Greenland Eskimos do not suffer from cardio-vascular diseases and in their blood there are significantly lower levels of cholesterol in comparison to Europeans after consumption of huge amount fatty meat. The secret is in character of the present lipid alone consisting from scarce unsaturated fatty acids of so-called n-3 families. While neither human organism nor animals can produce these essential lipids, their intake is dependent on food. Contrary, marine plankton produce them in high amounts, and due to this fact fish, cetaceans and seals forming the lowest issues of marine food chain contain in their bodies high concentration of these beneficial substances. Freshwater fish also contain them, but in lower amounts. Content of lipid in individual fish varies in relation to species, but substantial is the fact that we need not to be afraid of it at all due to its exceptional ability to protect our blood vessels against sclerosis – atherosclerosis (Syptáková, 2006). Fish meat is recommended food in the human nutrition due to low content of fat and high content of proteins and mineral substances as well as optimal ratio of unsaturated fatty acids. Habánová (2005) reported that fish and fish products consumption has declined in comparison with 2002 by 0.2 kg to 4.2 kg and in comparison to recommended dose is lower by 1.8 kg. This represents almost half a decline in comparison to other EU inhabitants. For instance, the inhabitants of northern states, such as Norway, Finland and Sweden could boast with even 60 kilograms of consumed fish per one person during the year. Longevity, good health state as well as slimness are remarkable by Japanese who eat 90 kg of fish meat during the year (Demešová, 2008). Carp ranks among medium-years living to long-time living fish; some individuals can even live 20 - 30 years. Common weight of carp in free waters is 2 - 6 kg, but relatively frequent are also catching over 10 kg (Sedlár, 1987). MATERIAL AND METHODS For this study exemplars of common carp (Cyprinus carpio) were obtained i (...truncated)