The chemical form of mercury in fish.
نویسندگان
چکیده
The primary dietary source of neurotoxic mercury compounds is via the ingestion of methylmercury species accumulated in fish. Methylmercury from fish has been linked to neurological damage (Minamata disease) (1) and increased risk of myocardial infarction (2). Despite its importance, the complete chemical identity of the mercury coordination in animal tissue remains unknown. The toxic properties of any element are critically dependant on molecular form; for example, dialkylmercury derivatives are toxic at such low levels that they are considered supertoxic, whereas mercuric selenide has a relatively low toxicity and accumulates as an apparently benign detoxification product in marine mammals (3). Knowing the chemical nature of a potential toxicant is, thus, essential to understanding its toxic properties. Mercury is very flexible in its coordination of nonmetallic elements, with structurally characterized species exhibiting coordination numbers between two and eight (4 ). X-ray absorption spectroscopy (XAS) is ideally suited to identification of chemical forms in situ, but it previously has not been much applied to molecular toxicology. Samples of fresh fish, otherwise intended for human consumption, were obtained from a local fish market. The Hg LIII XAS (5) of three different fish—swordfish (Xiphias gladius), orange roughy (Hoplostethus atlanticus), and sand sole (Psettichthys melanostictus)—indicated Hg concentrations within the range expected (6.0, 1.2, and 0.4 M, respectively). The normalized spectra of swordfish and orange roughy were indistinguishable within the noise (sand sole was too “noisy” for comparison), indicating similar or identical chemical forms of mercury. This is notable given their different diets: orange roughy is midway in the food chain, feeding on crustaceans, small squid, and fish, whereas the exclusively fishand squid-eating swordfish is a top predator. Figure 1 compares the Hg LIII x-ray absorption near-edge spectrum of swordfish skeletal muscle with the solution spectra of selected standard compounds (6 ). Twenty-six different standards were compared overall, including glutathioneand selenium-containing species, and the fish spectra closely resemble only the spectrum of methylmercury cysteine (or structurally related species), which contains linear two-coordinate mercury with methyl and cysteinyl sulfur donors. Thus, the nearedge spectra indicate the coordination of the methylmercury in fish to be completed by an aliphatic thiol. Although XAS cannot
منابع مشابه
Hair Mercury Levels in Six Iranian Sub-populations for Estimation of Methylmercury Exposure: A Mini-review
Background: Mercury is widespread and persistent in the environment. One organic form of mercury, Methylmercury (MeHg), can accumulate in the food chain in aquatic ecosystems and lead to high concentrations of MeHg in fish, which, when consumed by humans, can result in an increased risk of adverse effects. Currently, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) has established...
متن کاملHematological changes in Tinca tinca after exposure to lethal and sublethal doses of Mercury, Cadmium and Lead
Tench, Tinca tinca, were exposed to three treatments (one acute lethal 96 hrs Lc50/48 hrs and two chronic sublethal 10 and 25% Lc50/504 hrs) each of Mercury, Cadmium and Lead and its behaviour as an indicator of impaired hematology was studied. It was observed that impairments in hematological parameters (increased/decreased Hct, Hb, RBC, WBC and Lct) were reflected in behaviour of fish in the ...
متن کاملBioaccumulation of mercury in some organs of two fish species from the Sanandaj Gheshlagh Reservoir, Iran
The purpose of this study was to monitor the concentrations of mercury in the edible muscle, gill, liver, and skin of common carp (Cyprinus carpio) and silver carp (Hypophthalmichthys molitrix), in the Sanandaj Gheshlagh Reservoir, Iran. Mercury concentrations were assayed using Shimadzu AA 6600 atomic absorption spectrophotometer, and the results were given as µg/g wet weight. The level of mer...
متن کاملLevels of Mercury in Persian Gulf Frozen Fish Species
Severe discharge of sewage and industrial effluents into the Persian Gulf leads to the deposition of various types of heavy metals, especially lead and mercury, in the muscles of fish. Total mercury and methylmercury contents were determined in the edible parts (muscle tissue, fillet) of two different most popular frozen fish species from the Persian Gulf to ascertain whether the concentrations...
متن کاملبررسی غلظت جیوه در آب و ماهی های سواحل جنوبی دریای خزر، ایران
Background and Objective: Mercury (Hg) contamination in marine ecosystems is a major threat to human health in the developing countries like Iran. The main route of mercury exposure is from consumption of fish and seafood. Upon entering mercury in human bodies, Hg is converted into methyl mercury, which may lead to serious implications including neurological disorders, reproductive abnormalitie...
متن کاملEvaluation the amount of Lead, Cadmium, Mercury, Nickel and Tin in canned tuna fish available in Neyshabur markets in 2017
Introduction Marine products play a significant role in providing food for the people of the world, but rapid population growth and industrialization have led to the introduction of pollutants such as heavy metals into aquatic animals, one of the main pollutants of these important food sources. Materials & Methods This study was conducted in 2017 on 30 canned tuna fish that were purchased ran...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Science
دوره 301 5637 شماره
صفحات -
تاریخ انتشار 2003