Formaldehyde is a naturally occurring organic compound, and an important industrial precursor to many other materials and organic compounds. Formaldehyde solution (formalin) is used as a disinfectant. Formaldehyde vapors are toxic, upon entry formaldehyde reacts readily with macromolecules, including DNA to form DNA-protein and DNA-DNA cross-links.

Propionic acid (PA), also known as propanoic acid, with chemical formula C3H6O2, is an organic acid used as a food additive and found naturally on the skin and in the gastrointestinal tract. It is a byproduct of fermentation reactions and is also produced industrially from ethylene or ethanol and carbon monoxide. Propionic acid is a fungicide and bactericide, registered to controlfungi and bacteria in stored grains, hay, grain storage areas, poultry litter,and drinking water for livestock and poultry. As a food preservative, propionic acid prevents mold in bread and baked goods, and it is used as a flavoring agent in cheese and other packaged goods. The U.S. Environmental Protection Agency considers it safe and therefore, has no limitation on its use. It has been demonstrated that PA lowers fatty acids content in liver and plasma, reduces food intake, exerts immunosuppressive actions and probably improves tissue insulin sensitivity. Thus increased production of PA by the microbiota might be considered beneficial in the context of prevention of obesity and diabetes type 2. The molecular mechanisms by which PA may exert this plethora of physiological effects are slowly being elucidated and include intestinal cyclooxygenase enzyme, the G-protein coupled receptors 41 and 43 and activation of the peroxisome proliferator-activated receptor γ, in turn inhibiting the sentinel transcription factor NF-κB and thus increasing the threshold for inflammatory responses in general. Taken together, PA emerges as a major mediator in the link between nutrition, gut microbiota and physiology. The sodium salt of propionic acid was previously approved in Canada as an active ingredient in Amino-Cerv (used to treat inflammation or injury of the cervix).

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.

Aluminum is an element with an atomic number of 13. On the periodic table of elements its symbol is Al. It belongs to a group of metals including lead and tin. Aluminum has been used for a long time. During Ancient Egypt, aluminum oxides were used in their glazes and pottery. The Romans also used this metallic element. During the 1800s, advances in research made it possible to produce pure aluminum. Aluminium is used in a huge variety of products including cans, foils, kitchen utensils, window frames, beer kegs and aeroplane parts. This is because of its particular properties. It has low density, is non-toxic, has a high thermal conductivity, has excellent corrosion resistance and can be easily cast, machined and formed. It is also non-magnetic and non-sparking. It is the second most malleable metal and the sixth most ductile. It is often used as an alloy because aluminium itself is not particularly strong. Alloys with copper, manganese, magnesium and silicon are lightweight but strong. They are very important in the construction of aeroplanes and other forms of transport. Aluminium is a good electrical conductor and is often used in electrical transmission lines. It is cheaper than copper and weight for weight is almost twice as good a conductor. When evaporated in a vacuum, aluminium forms a highly reflective coating for both light and heat. It does not deteriorate, like a silver coating would. These aluminium coatings have many uses, including telescope mirrors, decorative paper, packages and toys. Aluminium has no known biological role. Aluminium can accumulate in the body, and a link with Alzheimer’s disease has been suggested but not proven. Aluminum-containing raw materials are used safely and extensively in cosmetics, pharmaceuticals and over-the-counter (OTC) drug products. In cosmetics, they function as pigments and thickening agents. Aluminum compounds also function as active ingredients in OTC drugs such as antacids and antiperspirants. Aluminum-containing ingredients have several uses in cosmetics and personal care products. Aluminum salts are used as antiperspirants to control sweat. Antiperspirant ingredients are regulated as over-the-counter (OTC) drugs by the U.S. Food and Drug Administration (FDA). A manufacturer can only use the aluminum active ingredients that have been approved as safe and effective by the FDA as listed in the OTC antiperspirant monograph. These products can only be used according to the guidelines established in this monograph. Aluminum may also be present in cosmetic colors. Aluminum powder is FDA approved and may be safely used in coloring externally applied cosmetics, including cosmetics intended for use in the area of the eye, [21 CFR §73.2645 Aluminum powder.]. In addition, aluminum is a common component in other cosmetic colors where it may be used as a substrate upon which another color is precipitated. Because the resulting color is not water-soluble, this can prevent ‘bleeding’, for example with lipstick. There are other uses of aluminum-containing ingredients in cosmetics, such as use as thickening agents. Under federal law, the safety of all ingredients must be substantiated by the manufacturer of the product before it is placed on the market. Aluminum compounds (alum) are the most widely used adjuvants in veterinary and human vaccines. Alum facilitates effectiveand long-lasting protective immunity in hosts, mainly by inducing antibody responses. Alum was found toinduce endogenous CD4+T cells and antibody production as well as to induce priming of CD8+T cells. These effects are shown to beindependent of the inflammasome. Novel findings of unexpected beneficial effects of decreased HBV (Hepatitis B virus) viral load and HBeAg seroconversion in chronically infected patients, as well as significant tumor suppression in experimental mice following multiple alum-only injections were examined, revealing alum's potential clinical applications beyond its use as a simple tool in antigen preparation.

CHLORINE is a yellow-green gas at room temperature with a pungent suffocating odor. It is a very reactive and strongly oxidizing chemical element that belongs to the group of halogens with the atomic number 17 and symbol Cl. It is commonly used in sanitation, disinfection, and antiseptic processes.

Bismuth is a high-density, silvery, pink-tinged metal. Bismuth metal is brittle and so it is usually mixed with other metals to make it useful. Its alloys with tin or cadmium have low melting points and are used in fire detectors and extinguishers, electric fuses and solders. Bismuth oxide is used as a yellow pigment for cosmetics and paints, while bismuth(III) chloride oxide (BiClO) gives a pearly effect to cosmetics. Bismuth compounds have been widely used in medicine. After extensive use in the treatments of syphilis and other bacterial infections before the advent of modern antibiotics, bismuth compounds remain important for the treatment of several gastrointestinal disorders and also exhibit antimicrobial properties and cytotoxic activity, among others.

Chrysarobin was originally extracted from Goa powder, a substance deposited in the wood of Andira Araroba, Aguiar (Nat. Ord.—Leguminosae). Chrysarobin (1,8-dihydroxy-3-methyl-9-anthrone) has enol tautomer of 1,8,9-trihydroxy-3-methyl-anthracene. Chrysarobin exerts antipsoriatic action. The use of chrysarobin has a number of quite serious disadvantages, not the least of which is that it can result in severe staining and irritation of the skin. Chrysarobin is an anthrone skin tumor promoter.

Hydrastine is an alkaloid, one of the chief components of goldenseal (Hydrastis canadensis) which was discovered in 1851 by Alfred P. Durand. Goldenseal is unique from other hydrastine containing plants in that (-)-β- hydrastine is the only hydrastine isomer present, while the (+)-enantiomer is found in other hydrastine-containing plants. . While a number of therapeutic activities have been attributed to berberine, the pharmacological effects of hydrastine are less studied and its safety profile is poorly understood and to frame the relevant pharmacological effects of hydrastine within the specific stereochemistry found in goldenseal. Hydrastine has been shown to have several specific biological activities including, inhibition of tyrosine hydroxylase in PC-12 cells, a relaxant effect on guinea pig isolated trachea, and inhibition of several cytochrome P450 (CYP) enzymes. Toxicological studies performed on goldenseal powder in mice and rats indicate that at commonly used doses goldenseal supplements are non-toxic, thus its constituents are likely to be safe for human use when taken at reasonable doses. Despite goldenseal’s widespread usage, the pharmacokinetics of hydrastine in humans has not been adequately described. While it is difficult to determine the proper dosage range for any herbal product, a recent extensive survey of the literature suggests a daily dose of Hydrastis in the range of 0.9 to 3 g per day. Hydrastine has been reported to elicit abortifacient effects and induce preterm labor in pregnant women when taken orally.

Cobalt is a lustrous, silvery-blue magnetic metal. Cobalt is a bioessential element due to its location at the centre of vitamin B12. Vitamin B12 plays a number of vital roles in the physiology of the human body. Cobalt is also important in treatments of radiotherapy in the form of the isotope 60Co. Other medical uses of cobalt include the detection of tumours and metastases, sterilisation of surgical equipment and the imaging of damage to the brain. Cobalt is also used in the prosthetic alloys sector, being utilised in hip, knee and dental replacements. There are inorganic cobalt complexes that elicit biological effects with potential use as pharmaceutical agents. Three classes of cobalt complexes are present: 1) complexes that directly act on biomolecules through ligand exchange, 2) complexes that modify the activity of ligated drugs and 3) complexes that are activated by bioreduction to either (I) yield a cobalt effector species or (II) release a small molecule drug. Cobalt can cause a distinctive, rapidly progressive and reversible depression of cardiac systolic function, which is readily distinguished from other causes of cardiomyopathy.