Mercury, a toxic heavy metal, exists in various forms, including elemental, inorganic, and organic (methylmercury). These forms differ in their toxicity and effects on multiple body systems, such as the nervous, digestive, and immune systems, as well as the lungs, kidneys, skin, and eyes. Mercury poisoning can result from exposure to high levels of mercury, and it can cause severe health problems, particularly in infants and young children.
Sources of Mercury:
Mercury occurs naturally in the earth’s crust and is released into the environment through volcanic activity, weathering of rocks, and human activities. Human activity, especially from coal-fired power stations, residential coal burning, industrial processes, waste incineration, and mining for metals like mercury and gold, is the primary cause of mercury releases into the environment. It is also found in other places, such as amalgam fillings used since the 1800s.[2]
Methylmercury Bioaccumulation:
Once in the environment, mercury can be transformed by bacteria into methylmercury, accumulating in fish and shellfish. As larger predatory fish consume smaller fish containing methylmercury, the mercury biomagnifies the food chain. This phenomenon results in higher mercury concentrations in large predatory fish such as swordfish, posing a risk to those who consume them.[3]
Exposure to Mercury:
Mercury exposure occurs through various means, the most commonly known being consuming fish and shellfish contaminated with methylmercury and occupational inhalation of elemental mercury vapors. Less common exposure is amalgam fillings and in utero. While there is much debate on amalgam fillings[4] (the word amalgam means mercury and another metal), it has been shown that even a 25-year-old tooth can continue to expose someone to mercury vapor. Check out this video to learn more!
Another unknown yet common exposure is during utero! During this time, the mother passes on her toxic load along with the nutrients to the child. This is an unknown and scary thing to learn, making it all the more important to share and understand where our toxic load comes from.
Factors Affecting Health Effects:
Several factors determine the severity of health effects from mercury exposure, including the type of mercury, the dose, the age of the exposed person (with fetuses being most susceptible), the duration of exposure, and the route of exposure (inhalation, ingestion, or dermal contact).[5]
Vulnerable Groups:
Two groups are particularly sensitive to mercury’s effects. Fetuses are highly vulnerable to developmental impacts, as maternal consumption of fish and shellfish contaminated with methylmercury can adversely affect a baby’s developing brain and nervous system. Cognitive functions, memory, attention, language, and fine motor skills may be impaired in children exposed to methylmercury in the womb.[6]
People regularly exposed to high levels of mercury, such as those referenced earlier in this article, are also at risk. Certain subsistence fishing populations have reported cognitive impairment in children due to mercury-contaminated fish consumption.
Minamata Disease – A Tragic Example:
One of mercury exposure’s most significant impacts on public health occurred in Minamata, Japan, between 1932 and 1968. A factory’s waste liquid containing high methylmercury concentrations was discharged into Minamata Bay, contaminating the fish and shellfish that locals relied upon for their livelihood. Thousands of people suffered from Minamata disease, exhibiting brain damage, paralysis, and other severe neurological effects.
Health Effects of Mercury Exposure:
Both elemental and methylmercury are toxic to the central and peripheral nervous systems. Inhaling mercury vapor can harm the nervous, digestive, immune systems, lungs, and kidneys and even be fatal. Inorganic mercury salts are corrosive to the skin, eyes, and gastrointestinal tract, and ingestion may lead to kidney toxicity.[4]
Symptoms of mercury exposure range widely and can include tremors, insomnia, memory loss, neuromuscular effects, headaches, and cognitive and motor dysfunction. With studies showing that diseases such as Alzheimer’s may be linked to mercury poisoning,[1] there may be more concerns associated with this nasty toxin.
Conclusion:
Mercury exposure is a serious public health concern with adverse effects on various body systems, especially the nervous system. Understanding the sources of mercury and its impact on vulnerable populations is crucial for implementing preventive measures and safeguarding the health of communities worldwide. Continued research and awareness will help us combat the silent dangers of mercury and strive for a mercury-free future.
References:
- Siblerud R, Mutter J, Moore E, Naumann J, Walach H. A Hypothesis and Evidence That Mercury May be an Etiological Factor in Alzheimer’s Disease. Int J Environ Res Public Health. 2019 Dec 17;16(24):5152. doi: 10.3390/ijerph16245152. PMID: 31861093; PMCID: PMC6950077.
- Sources of Mercury. https://www.epa.gov/mercury/basic-information-about-mercury
- Gareth Harding, Conceptualization, Formal analysis, Funding acquisition, Investigation, Methodology, Writing – original draft, Writing – review & editing, John Dalziel, Investigation, Methodology, and Peter Vass, Investigation. Methodology, Bioaccumulation of methylmercury within the marine food web of the outer Bay of Fundy, Gulf of Maine. PLoS One. 2018; 13(7): e0197220. 2018 Jul 16. doi: 10.1371/journal.pone.0197220. PMCID: PMC6047777. PMID: 30011281
- Mercury and health. https://www.who.int/news-room/fact-sheets/detail/mercury-and-health
- Stephan Bose-O’Reilly, MD, MPH, Kathleen M. McCarty, ScD, MPH, Nadine Steckling, BSc, and Beate Lettmeier, PhDa. Mercury Exposure and Children’s Health. Author manuscript; available in PMC 2011 May 17.Curr Probl Pediatr Adolesc Health Care. 2010 Sep; 40(8): 186–215. doi: 10.1016/j.cppeds.2010.07.002. PMCID: PMC3096006. NIHMSID: NIHMS294964. PMID: 20816346.
- Emily Okena and David C. Bellinger. Fish consumption, methylmercury, and child neurodevelopment. 2008 Apr; 20(2): 178–183.doi: 10.1097/MOP.0b013e3282f5614c. PMCID: PMC2581505. NIHMSID: NIHMS75230. PMID: 18332715.