Mercury, with the chemical symbol Hg (from Greek "Hydrargyros"), is the only metal adopting liquid form in room temperature. Mercury appears in seven natural isotopic forms. The metal is extracted from the mineral cinnabar, mercuric sulfide, in former times used also for paint. Mercury has fascinated people for millennia, as a heavy liquid metal. However, because of its toxicity, many uses of mercury are being phased out or are under review. It is now mainly used in the chemical industry as catalysts. It is also used in some electrical switches and rectifiers. Previously its major use was in the manufacture of sodium hydroxide and chlorine by electrolysis of brine. These plants will all be phased out by 2020. Elemental mercury is used in thermometers, blood pressure devices, and thermostats because its ability to expand and contract uniformly makes it useful for measuring changes in temperature and pressure. Mercury is also used in dental fillings, paints, soaps, batteries, and fluorescent lighting. Mercury will dissolve numerous metals to form amalgams and is used to extract gold dust from rocks by dissolving the gold and then boiling off the mercury. The amalgam used in dental fillings contains tin and silver alloyed with mercury. Because it works as a biocide, mercury has been used as a fungicide in paint, though this kind of paint is no longer sold. Mercury and its compounds used in dental practice may be responsible for release of mercury into the oral cavity. Compounds of mercury tend to be much more toxic than the element itself, and organic compounds of mercury (e.g., dimethyl-mercury) are often extremely toxic and may be responsible in causing brain and liver damage. Human exposure to mercury has increased through anthropogenic mercury emissions from fuel combustion, municipal incinerators, and chemical industries. Mercury is considered a major environmental toxicant throughout the world. Mercury is harmless in insoluble form, but vapor or soluble forms such as inorganic mercury or methylmercury can be extremely toxic to humans. Most human mercury exposure occurs through inhalation of elemental mercury vapor released from dental amalgam and through the consumption of fish contaminated with methylmercury.

Polaprezinc is a zinc-containing molecule and used for the therapy of gastric ulcer. It has been reported that this compound inhibits the induction of TNF-a as well as cellular signaling of TNF-a. Polaprezinc has been shown to exert an anti-oxidant property in a tube experiment and accelerate the healing of gastric ulcer in humans. Polaprezinc inhibited EtOH-induced cytochrome c reduction. Protection by polaprezinc was microscopically associated with the prevention of monolayer disruption. In an animal model of chemotherapy-induced oral mucositis polaprezinc improves the recovery from 5-fluorouracil–induced oral mucositis in hamsters. Polaprezinc ameliorates mucosal ulceration in acetic acid-induced experimental oral mucositis in hamsters. Polaprezinc is potentially useful for prevention of oral mucositis and improvement of quality of life without reducing the tumor response. Polaprezinc is in phase II clinical trial for the treatment of taste disorders.

Zinc aspartate is an approved drug, used to treat zinc deficiency in humans. Zinc aspartate regulates the production of the growth hormone and sex hormones (it is necessary for the production of sperm cells and egg cells). It reduces the body’s susceptibility to infections and allergies. It promotes the proper secretion of insulin by the pancreas. Zinc deficiency causes: disorders in the functioning of the skin, the digestive system, the nervous system, the immunological system, and the skeletal system. Significant zinc deficiency can cause dwarfism and genital underdevelopment. Zinc aspartate suppresses experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis (MS), as well as effector T cell functions in vitro.

Boron gluconate is a boron-containing dietary supplement. Calcium salt of boron gluconate is used as a calcium supplement in veterinary to treat hypocalcemia (also called parturient paresis and commonly called milk fever) in cattle, sheep, and goat.

Magnesium ascorbate is a non-acidic buffered form of Vitamin C and a source of the essential mineral Magnesium. The in vitro model system consisted of the isolated section of rat small intestine. The sources of magnesium ion (Mg2+) were magnesium chloride, magnesium sulphate, magnesium acetate, magnesium lactate, magnesium hydrocitrate and magnesium ascorbate. Magnesium ions from magnesium ascorbate were absorbed after the first 15 minutes to the highest extent of all salts, but after 120 minutes their absorption was the smallest of all. The use of magnesium ascorbate in food supplements may lead to an additional exposure to vitamin C and Magnesium.

Silver is a soft metal that is used medically in surgical instruments, dental prostheses, and alloys. According to FDA final rule, all over-the-counter drug products containing colloidal silver ingredients or silver salts for internal or external use are not generally recognized as safe and effective and are misbranded.

Molybdenum Hexachloride is an inorganic diamagnetic compound used for catalytic polymerization of cycloolefins.

Selenium (Se) is mineral that is found in soil and occurs naturally in certain foods (such as whole grains, Brazil nuts, sunflower seeds, and seafood). Selenium, which is nutritionally essential for humans, is a constituent of more than two dozen selenoproteins that play critical roles in reproduction, thyroid hormone metabolism, DNA synthesis, and protection from oxidative damage and infection. Selenium is used to treat or prevent selenium deficiency. Selenium deficiency produces biochemical changes that might predispose people who experience additional stresses to develop certain illnesses. For example, selenium deficiency in combination with a second stress (possibly a viral infection) leads to Keshan disease, a cardiomyopathy that occurred in parts of China prior to a government-sponsored selenium supplementation program that began in the 1970s. Before the Chinese government supplementation program, adults in the Keshan disease areas had average selenium intakes of no more than 11 mcg/day; intakes of at least 20 mcg/day protect adults from Keshan disease. Selenium has been used in alternative medicine as an aid to treat Hashimoto's thyroiditis, and to treat high cholesterol. Selenium is an important enzyme in the prevention of cellular damage by free radicals and reactive oxygen species. Selenium is first metabolized to selenophosphate and selenocysteine. Selenium incorporation is genetically encoded through the RNA sequence UGA. This sequence is recognized by RNA ste loop structures called selenocysteine inserting sequences (SECIS). These structures require the binding of SECIS binding proteins (SBP-2) to recognize selenocystiene. The specialized tRNA is first bound to a serine residue which is then enzymatically processed to a selylcysteyl-tRNA by selenocystiene sythase using selenophosphate as a selenium donor. Other unidentified proteins are required as part of the binding of this tRNA to the ribosome. Numerous studies in animal models and more recent studies in humans have demonstrated cancer chemopreventive effects with Se. There is extensive evidence that monomethylated forms of Se are critical metabolites for chemopreventive effects of Se. Induction of apoptosis in transformed cells is an important chemopreventive mechanism. Apoptosis can be triggered by micromolar levels of monomethylated forms of Se independent of DNA damage and in cells having a null p53 phenotype. Cell cycle protein kinase cdk2 and protein kinase C are strongly inhibited by various forms of Se. Inhibitory mechanisms involving modification of cysteine residues in proteins by Se have been proposed that involve formation of Se adducts of the selenotrisulfide (S-Se-S) or selenenylsulfide (S-Se) type or catalysis of disulfide formation. Selenium may facilitate reactions of protein cysteine residues by the transient formation of more reactive S-Se intermediates. A novel chemopreventive mechanism is proposed involving Se catalysis of reversible cysteine/disulfide transformations that occur in a number of redox-regulated proteins, including transcription factors. A time-limited activation mechanism for such proteins, with deactivation facilitated by Se, would allow normalization of critical cellular processes in the early stages of transformation. Randomized controlled trials of selenium supplementation for cancer prevention have yielded conflicting results. In 2003, the FDA allowed a qualified health claim on foods and dietary supplements containing selenium to state that while “some scientific evidence suggests that consumption of selenium may reduce the risk of certain forms of cancer… FDA has determined that this evidence is limited and not conclusive”. Selenium is available in multivitamin/multimineral supplements and as a stand-alone supplement, often in the forms of selenomethionine or of selenium-enriched yeast (grown in a high-selenium medium) or as sodium selenite or sodium selenate.

Silicon is a trace element that resembles carbon and can form silicon-carbon as well as silicon-oxygen, silicon-hydrogen and silicon-nitrogen bonds. It may have a role in a number of areas of human physiology and metabolism, especially bone and connective tissue formation, but possibly also gene expression and cardiovascular health. The exact biological role(s) of silicon in bone health is still not clear, although a number of possible mechanisms have been suggested, including the synthesis of collagen and/or its stabilization, and matrix mineralization. Silicone-based products are widely used in the management of hypertrophic scarring and keloids. The mechanism of action of silicone therapy has not been completely determined but is likely to involve occlusion and hydration of the stratum corneum with subsequent cytokine-mediated signaling from keratinocytes to dermal fibroblasts.