Animal Source Foods
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Mercury is a heavy, liquid metal emitted from natural sources (volcanoes and some ores) and human sources from industrial wastes. From the atmosphere, mercury cycles from rainwater into lakes and oceans, where it is converted by microbial activity into organic methylmercury (32). Mercury in fish exists in the form of methylmercury (CH3-Hg)+ which is a fat-soluble organic compound and highly toxic for the human central nervous system. Inorganic mercury liquid (for example, from ancient thermometers) is poorly absorbed following ingestion, and elemental mercury does not readily cross tissue barriers (32). In contrast, methylmercury is readily absorbed and actively transported into tissues, then accumulated in the brain and nerves. Methylmercury causes neuropathy (ataxia, numbness, paralysis, coma, death) in humans and mammals like cats, but is not toxic in fish and shellfish except for in very high doses (32). Methylmercury can cross the placenta, and fetal exposure correlates with maternal exposure. The famous poisoning of methylmercury by eating fish contaminated from industrial wastes is called Minamata disease or syndrome (11, 31–32).
Trace Elements In Alzheimer’s Disease
Zaven S. Khachaturian, Teresa S. Radebaugh in Alzheimer’s Disease, 2019
Another element that has been postulated to possibly be involved in AD is mercury. Mercury, an ubiquitous, nonessential element, has long been known to be toxic to the central nervous system in its inorganic (elemental or mercuric salt) or organic (methylmercury) forms. The most common source of elemental Hg is in dental amalgams. Toxicity can occur from inhalation of Hg vapors. Of inhaled Hg vapor, 80% is retained. Mercuric salts are found in medications, in catalytic agents used in plastic manufacturing, and in food. Organic Hg, primarily in the form of methylmercury, is in food, paint, fungicides, seeds, cosmetics, and medications. Exposure to methylmercury in the food chain, primarily in seafood, represents one of the major forms of exposure for humans.
Environmental Toxins and Chronic Illness
Aruna Bakhru in Nutrition and Integrative Medicine, 2018
Methylmercury, an organic form of mercury that has been reported in many studies as a significant environmental pollutant often found in certain types of fish, accumulates in the brain, primarily in myelin sheaths, leading to demyelination. In terms of large-scale, overt methylmercury poisoning, probably the most famous case is pollution of Minamata Bay in Japan in the 1950s. Symptoms that were seen in those exposed to the polluted water in Minamata Bay primarily through ingestion of fish include ataxia, speech impairment, constriction of visual fields, hypoesthesia, dysarthria, hearing impairment, and sensory disturbances. What may be even more significant than the original occurrence is the fact 40 years after the spill and 30 years after a fishing ban was enacted symptoms of mercury neurotoxicity still persisted. Other studies, such as those performed on Amazonian children exposed to methylmercury as the result of local gold mining, demonstrated neurotoxic effects. In addition, more than 80% of the children had levels of hair mercury high enough to impact brain development. Neuropsychological testing in these children demonstrated deficits in motor function, attention, and visuospatial performance. In the United States, a study of patients in an internal medicine practice in San Francisco who ingested large fish regularly had blood levels of mercury above 5 mcg/L and demonstrated issues with fatigue, hair loss, troubled thinking, memory loss, muscle aches, and headaches. Furthermore, many of these patients reported a metallic taste in the mouth.
Potentially toxic elements (PTEs) in fillet tissue of common carp (Cyprinus carpio): a systematic review, meta-analysis and risk assessment study
Published in Toxin Reviews, 2021
Yadolah Fakhri, Babak Djahed, Ali Toolabi, Amir Raoofi, Abdolmajid Gholizadeh, Hadi Eslami, Mahmoud Taghavi, Mohammad reza Alipour, Amin Mousavi Khaneghah
Natural sources of Hg in the environment are volcanic emissions and weathering of Hg bearing rocks (Marrugo-Negrete et al. 2015). However, this element can pollute the environment through anthropogenic sources including coal combustion, fossil fuels, metal production especially gold, medical and municipal solid wastes incineration and emissions from the chlor-alkali process and cement production (Al Mukaimi et al. 2018). Marine and freshwater organisms are capable of bioaccumulates Hg as methylmercury and consequently poses humans at risk of heal hazards (Al Mukaimi et al. 2018). Therefore, fish and seafood consumption is considered as the major route of human exposure with Hg (Anual et al. 2018). It is believed that methylmercury can be accounted for a source of more than 90% of the total mercury in fish and seafood (Commission 2006). It is estimated that almost 95% of methyl mercury present in fish ingested by a human can inter to the bloodstreams and reach peak concentrations in blood after 4–14 h. Exposure to methylmercury is linked to developmental delays, learning disabilities, and perhaps behavioral problems due to its ability to readily cross plasma membranes, the blood-brain barrier and placenta (Anual et al. 2018).
Development of a Natural Product Rich in Bioavailable Omega-3 DHA from Locally Available Ingredients for Prevention of Nutrition Related Mental Illnesses
Published in Journal of the American College of Nutrition, 2020
Christina N. Charles, Hulda Swai, Titus Msagati, Musa Chacha
Fish oil is currently the major dietary source of omega-3 DHA. However, according to Lane and colleagues, there are several limitations to relying fish oils as a source of supply of omega-3 DHA (17). Some of these limitations include the undesirable odors, flavors, and tastes of fish oils which discourage consumers from consuming them in their pure forms and neither is traditional supplementation much appreciated. Furthermore, some fish contain high levels of methyl-mercury, which creates a risk of mercury poisoning to consumers (17). Also, some fish oils have been found to contain environmental contaminants such as dioxins and polychlorinated biphenyls which dissuade its use. In addition, fish oil production has reached maximum global production and its stock is decreasing throughout the world (17), thus may not be a sustainable source of DHA, especially in resource-poor countries. This calls for development of products or formulations that are rich in preformed DHA and other health promoting compounds from other sources.
Mercury disrupts redox status, up-regulates metallothionein and induces genotoxicity in respiratory tree of sea cucumber (Holothuria forskali)
Published in Drug and Chemical Toxicology, 2020
Khaoula Telahigue, Imen Rabeh, Safa Bejaoui, Tarek Hajji, Salwa Nechi, Emna Chelbi, M’hamed El Cafsi, Nejla Soudani
Like other estuarine and coastal marine organisms, sea cucumbers are exposed to various anthropogenic stressors. In this respect, Turk Culha et al. (2016) have reported that sea cucumbers could be used as bioindicator organisms for detecting xenobiotic contamination in marine environments. Among these xenobiotics, mercury (Hg) is increasingly featuring as one of the most toxic chemical compounds in terrestrial and aquatic ecosystems (Luoma and Rainbow 2008). In the aquatic systems, this metal is present in elemental, inorganic, and organic forms. It accumulates in the very toxic form of methylmercury, via the food chain, in the top predators (Windom and Kendall 1979). Like other metals with no physiological functions, mercury enters organisms by molecular mimicry, utilizing inherent transporters for essential metals (Martinez-Finley et al. 2012). Once inside the cell, and due to its reactive property, it can enhance the intracellular formation of reactive oxygen species and promote cellular oxidative stress (Verlecar et al. 2008, Kong et al. 2012). This induction of oxidative stress has been observed in several aquatic organisms exposed to mercury stress as bivalves (Géret 2002), crustaceans (Elumalai et al. 2007) and fish (Monteiro et al. 2010).
Related Knowledge Centers
- Bioaccumulation
- Chloride
- Functional Group
- Hydroxide
- Methyl Group
- Ion
- Organomercury Chemistry
- Toxicant
- Mercury
- Chemical Formula