lovesouthernsocial.com

Mercury contamination is a threat to both health and ecosystems

Edited and resized image by Matteo Fusco is available on Unsplash

Mercury is a heavy metal that, under normal conditions, is found in low concentrations in the environment, being naturally released due to erosive processes and volcanic eruptions.

Environmental contamination by mercury is, therefore, the result of anthropic actions, that is, human actions involving this element. The main anthropogenic sources of mercury are:

• Burning coal, oil and wood: the process emits mercury contained in these materials into the atmosphere;
• Manufacture of products that use mercury as a raw material, such as thermometers and fluorescent lamps;
• Inappropriate disposal of mercury after its use in industrial processes, such as chlorine-soda production;
• Incorrect disposal of electro-electronic products containing mercury;
• Gold mining, in which mercury is used to facilitate the particle separation process.

Brazil does not produce mercury, as it has no reserves of cinnabar (commercially exploited form of mercury). Therefore, the country imports it mainly from the USA and Spain. According to a study by the Department of Geochemistry at the Universidade Federal Fluminense, the main sources of environmental mercury contamination in Brazil are industrial effluents from the manufacture of caustic soda and gold mining in the Amazon region, which caused the mercury contamination of many Brazilian rivers. .

The burning of large forest areas in the Amazon region is also identified in a report by the Ministry of the Environment as a significant source of mercury emissions in the country. In addition, there is the problem of soil contamination due to incorrect disposal of products that contain mercury, encompassed by the National Solid Waste Policy.

The three forms in which mercury presents itself are:

Elemental or metallic mercury (Hgº)

Most atmospheric mercury emissions occur in the form of metallic or elemental mercury. This form of the metal is very stable, which allows it to be transported over long distances and remain in the environment for a long time.

Main uses: used as raw material for products such as thermometers, barometers (devices to measure blood pressure) and sphygmomanometers (devices to measure blood pressure); of fluorescent lamps; electrical and electronic switches, industrial devices (thermostats and pressure switches); and amalgams for dental use; and in mining activities.

Routes of exposure: human exposure to metallic mercury occurs mainly through the inhalation of vapors in dental offices, foundries and places where mercury has been spilled or released. Thus, the people who are most exposed to this form of mercury are workers in the dental sector and factories that make use of mercury.

Consequences of contamination: inhalation of high concentrations of metallic mercury vapor can damage the lungs, and chronic inhalation leads to neurological disorders, memory problems, skin rashes and kidney failure. It is possible to identify elemental mercury poisoning via urinalysis.

Elemental mercury binds to other elements, giving rise to two other forms of mercury: organic and inorganic compounds.

Methylmercury [CH₃Hg]⁺ (organic compound)

Methylmercury is just one of the representatives of organic mercury compounds, however, it is considered the most important due to its high toxicity for the human body.

It is produced from elemental mercury, synthesized by bacteria present in aquatic environments as a result of the detoxification process. In this process, mercury (Hg) binds to a methyl group (a carbon bonded to three hydrogens-CH₃).

Methylmercury is then incorporated into the aquatic ecosystem and accumulates in the tissue of aquatic organisms, so that the higher the organism's position in the food chain, the greater the concentration of methylmercury in its organism.

Therefore, when consuming fish that occupy the top of the food chain (salmon, tuna, trout and others), the individual is possibly ingesting a food contaminated by methylmercury, and as a consequence, becoming intoxicated.

Main uses: there is no industrial or commercial use for methylmercury

Routes of exposure: ingestion of fish contaminated by methylmercury, ingestion of contaminated water.

Consequences of contamination: ingestion of methyl-Hg causes damage to the central nervous system, neural dysfunction, and in severe cases, it leads to paralysis and death.

• Mercury contaminated fish: a threat to the environment and health

inorganic mercury

Inorganic mercury is represented by a set of mineral salts and compounds. These are formed by the binding of mercury with elements such as sulfur and oxygen.

Main uses: manufacture of batteries; of paints and seeds; biocides in the paper industry, antiseptic; chemical reagents; protective paints for ship hulls; pigments and dyes.

Routes of exposure: the main route of exposure is occupational - it is when workers come into contact with inorganic mercury through inhalation and dermal contact. Another route of exposure to be considered is the ingestion of pharmaceutical products and the consumption of contaminated food.

Consequences of contamination: contact with the dermis causes skin rashes, and ingestion of a high concentration of inorganic mercury causes irritation and corrosion of the digestive system. Like elemental mercury, inorganic mercury poisoning can be identified by examining the urine.

Symptoms of mercury poisoning

In humans, contact with mercury can cause from mild symptoms such as itching and redness of the skin and eyes to severe interference with cell metabolism, in case of prolonged exposure. Know the main symptoms of mercury poisoning:

• Fever
• tremors
• Allergic skin and eye reactions
• Somnolence
• delusions
• Muscle weakness
• Nausea
• headache
• Slow reflexes
• memory failure
• Kidney, liver, lung and nervous system malfunction

Disposal of mercury-containing products

According to the Preliminary Report on Mercury in Brazil, the electro-electronic sector generates a significant amount of waste, mainly batteries, cells and cell phones, which are normally discarded in landfills without proper treatment.

One measure that aims to reduce this problem is the National Solid Waste Policy (PNRS), sanctioned in 2010, which, among many points, defines the obligation of manufacturers, importers, distributors and traders of batteries, fluorescent lamps, and steam sodium and mercury and mixed light, and electronic products and their components in structuring and implementing reverse logistics systems, through the return of the products after use by the consumer, which go beyond the public urban cleaning service and solid waste management .

However, it is up to the consumer to collaborate with the process. The Ministry of the Environment presents in its report data from ANEEL that claim that only 2% of Brazilians deliver electronic devices for recycling.

If you have difficulty knowing how and where to dispose of these products, the eCycle portal help you. Find collection posts on the free search engine of eCycle portal.