Formaldehyde

Formaldehyde can affect you if it is breathed in or if it passes through your skin and when swallowed. This should be handled as a carcinogen with extreme caution. Formaldehyde could cause a skin allergy and can irritate the nose, throat, and mouth. It is extremely flammable gas and a dangerous fire hazard. It is toxic by inhalation, skin contact, and ingestion, though there is limited evidence of a carcinogenic effect. Formaldehyde is corrosive, could cause burns and sensitization by skin contact. When producing formaldehyde resins there is the use of plywood, particle board, paper, and urea (formaldehyde foam). Embalmers and laboratory workers could be exposed to 1ppm or more of formaldehyde. Major industrial consumers of formaldehyde resins are plastic parts, decorative laminates, photographic film, and plywood paneling. There are high formaldehyde exposures seen in carpet installers and parquet tile fitters. Formaldehyde can also exist as a polymer and as a trimer. Formaldehyde can also be listed as Formalin. Some symptoms of formaldehyde if it is inhaled is a burning sensation, cough, headache, nausea, and shortness of breath. If it gets into the eyes symptoms could be watering of the eyes, redness, pain, and blurred vision.

**Formaldehyde** is an [|organic compound] with the [|formula] CH2O. It is the simplest form of [|aldehyde], hence its [|systematic name] **methanal**. A gas at room temperature, formaldehyde is colorless and has a characteristic pungent, irritating odor. It is an important precursor to many other chemical compounds, especially for polymers. In 2005, annual world production of formaldehyde was estimated to be 23 million tonnes (50 billion pounds). [|[3]] Commercial solutions of formaldehyde in water, commonly called **formalin**, were formerly used as [|disinfectants] and for preservation of biological specimens. In view of its widespread use, toxicity and volatility, exposure to formaldehyde is a significant consideration for human health.

Forms
Formaldehyde is more complicated than many simple carbon compounds because it adopts different forms. One important derivative is the cyclic [|trimer] metaformaldehyde or [|trioxane] (CH2O)3. There is also an infinite polymer called [|paraformaldehyde]. When dissolved in water, formaldehyde combines with water to form [|methanediol] or methylene glycol H2C(OH)2. The diol also exists in equilibrium with a series of [|oligomers] (short polymers), depending on the concentration and temperature. A saturated water solution, that contains about 40% formaldehyde by volume or 37% by mass, is called "100% formalin". A small amount of [|stabilizer], such as [|methanol] , is usually added to limit [|oxidation] and [|polymerization]. A typical commercial grade formalin may contain 10–12% methanol in addition to various metallic impurities.

Uses
In photography, formaldehyde is used in low concentrations for [|process C-41] (color negative film) stabilizer in the final wash step, [|[17]] as well as in the [|process E-6] pre-bleach step, to obviate the need for it in the final wash. Formaldehyde is used extensively in the woodworking and cabinet-making industries. [|Urea-formaldehyde] is used in the glues that bond [|particle board] together. [|[18]] The particle board is used underneath wood veneer and plastic laminate. Cabinets, bank counters, and veneered and laminated woodwork all use particle board containing urea-formaldehyde under the plastic laminate and wood veneer.[// [|citation needed] //]

Industrial applications
Formaldehyde is a common building block for the synthesis of more complex compounds and materials. In approximate order of decreasing consumption, products generated from formaldehyde include [|urea formaldehyde resin], [|melamine resin] , [|phenol formaldehyde resin] , [|polyoxymethylene plastics] , [|1,4-butanediol] , and [|methylene diphenyl diisocyanate]. [|[3]] The [|textile industry] uses formaldehyde-based resins as [|finishers] to make fabrics crease-resistant. [|[19]] Formaldehyde-based materials are key to the manufacture of automobiles, and used to make components for the transmission, electrical system, engine block, door panels, axles and brake shoes. The value of sales of formaldehyde and derivative products was over $145 billion in 2003, about 1.2% of the Gross Domestic Product (GDP) of the United States and Canada. Including indirect employment, over 4 million work in the formaldehyde industry across approximately 11,900 plants in the U.S. and Canada. [|[20]] When reacted with phenol, urea, or melamine, formaldehyde produces, respectively, hard thermoset phenol formaldehyde resin, urea formaldehyde resin, and melamine resin, which are commonly used in permanent adhesives such as those used in [|plywood] or [|carpeting]. It is used as the [|wet-strength] resin added to sanitary paper products such as (listed in increasing concentrations injected into the paper machine headstock chest) facial tissue, table napkins, and roll towels. They are also foamed to make [|insulation], or [|cast] into moulded products. Production of formaldehyde resins accounts for more than half of formaldehyde consumption. Formaldehyde is also a precursor to polyfunctional [|alcohols] such as [|pentaerythritol], which is used to make [|paints] and [|explosives]. Other formaldehyde derivatives include [|methylene diphenyl diisocyanate], an important component in [|polyurethane] paints and foams, and [|hexamine] , which is used in phenol-formaldehyde resins as well as the explosive [|RDX]. Formaldehyde has been found as a contaminant in several bath products, at levels from 54–610 ppm: it is thought to arise from the breakdown of preservatives in the products. [|[21]]

Disinfectant and biocide
An aqueous solution of formaldehyde can be useful as a disinfectant as it kills most [|bacteria] and fungi (including their spores). Formaldehyde solutions are applied topically in medicine to dry the skin, such as in the treatment of [|warts]. Many aquarists use formaldehyde as a treatment for the parasites // [|Ichthyophthirius multifiliis] // and // [|Cryptocaryon irritans] //. [|[22]] Formaldehyde is used to inactivate bacterial products for toxoid vaccines (vaccines that use an inactive bacterial toxin to produce immunity). It is also used to kill unwanted viruses and bacteria that might contaminate the vaccine during production. [|[23]] [|Urinary tract infections] are also often treated using a derivative of formaldehyde (methenamine), a method often chosen because it prevents overuse of antibiotics and the resultant development of bacterial resistance to them. In an acid environment methenamine is converted in the kidneys to formaldehyde, which then has an antibacterial effect in the urinary tract. This is not safe for long term use due to the carcinogenic effect of formaldehyde. Some topical creams, cosmetics and personal hygiene products also contain derivatives of formaldehyde as the active ingredients that prevent the growth of potentially harmful bacteria.

Tissue fixative and embalming agent
Octopodes preserved in formaldehyde solution Formaldehyde preserves or [|fixes] tissue or cells by a mixture of reversible (short exposure time and low temperatures) and irreversible (long exposure time and higher temperatures) cross-linking of primary [|amino groups] in proteins with other nearby nitrogen atoms in protein or [|DNA] through a -CH2- linkage. This is exploited in [|ChIP-on-chip] transcriptomics experiments, where nucleotide-binding proteins are cross-linked to their cognate binding sites on the chromosome and analyzed to determine what genes are regulated by the proteins. Formaldehyde is also used as a denaturing agent in [|RNA] gel [|electrophoresis], preventing RNA from forming secondary structures. A solution of 4% formaldehyde fixes pathology tissue specimens at about one mm per hour at room temperature. Formaldehyde solutions are used as a [|fixative] for [|microscopy] and [|histology], although the percentage formaldehyde used may vary based on the method of analysis. Additionally, the methanol used to stabilize formaldehyde may interfere with the ability to properly fix tissue or cells, and therefore commercial formaldehyde preparations are available that are packaged in glass [|ampules] under an [|inert gas] to prevent the use of contaminating methanol for stabilization. Formaldehyde-based solutions are also used in [|embalming] to disinfect and temporarily preserve human and animal remains. It is the ability of formaldehyde to fix the tissue that produces the tell-tale firmness of flesh in an embalmed body. In post mortem examinations a procedure known as the "sink test" involves placing the lungs of an animal in an aqueous solution of formaldehyde; if the lungs float it suggests the animal was probably breathing or able to breathe at the time of death. Although formaldehyde solutions are commonly used as a biological preserving medium, usually for smaller specimens, it usually just prolongs the decaying process. Several European countries restrict the use of formaldehyde, including the import of formaldehyde-treated products and embalming. Starting September 2007, the European Union banned the use of formaldehyde due to its carcinogenic properties as a [|biocide] (including embalming) under the [|Biocidal Products Directive] (98/8/EC). [|[24]][|[25]] Countries with a strong tradition of embalming corpses, such as Ireland and other colder-weather countries, have raised concerns. Despite reports to the contrary, [|[26]] no decision on the inclusion of formaldehyde on Annex I of the Biocidal Products Directive for product-type 22 (embalming and taxidermist fluids) had been made as of September 2009. [|[27]]

Drug testing
Formaldehyde, along with 18 [|M] (concentrated) [|sulfuric acid] makes [|Marquis reagent] which can be used to identify [|alkaloids] and other compounds.

International bans
There are several web articles claiming that formaldehyde has been banned from manufacture or import into the European Union (EU) under REACH (Registration, Evaluation, Authorization, and restriction of Chemical substances) legislation. This appears to be misinformation, as official EU chemical databases contradict these claims as of February 19, 2010. This misconception has gained some ground. Formaldehyde is not listed in the Annex I of Regulation (EC) No 689/2008 (export and import of dangerous chemicals regulation), nor on a priority list for risk assessment. However, formaldehyde is banned from use in certain applications (preservatives for liquid-cooling and processing systems, slimicides, metalworking-fluid preservatives, and antifouling products) under the Biocidal Products Directive. [|[51]][|[52]] In the EU, the maximum allowed concentration of formaldehyde in finished products is 0.2%, and any product that exceeds .05% has to include a warning that the product contains formaldehyde. [|[45]] In the United States, a bill was passed in congress on July 7, 2010 regarding the use of formaldehyde in hardwood [|plywood], [|particle board] , and [|medium density fiberboard]. The bill limited the allowable amount of formaldehyde emissions from these wood products to .09 ppm, a standard which companies will have to meet by January, 2013. [|[53]] Formaldehyde was declared a toxic substance by the 1999 Canadian Environmental Protection Act. [|[54]]

Formaldehyde was the first [|polyatomic] [|organic] molecule detected in the [|interstellar medium] [|[8]] and since its initial detection has been observed in many regions of the [|galaxy]. Because of the widespread interest in interstellar formaldehyde it has recently been extensively studied, yielding new extragalactic sources. [|[9]] A proposed mechanism for the formation is the hydrogenation of CO ice, shown below. [|[10]]

H + CO → HCOHCO + H → H2CO (rate constant = 9.2×10−3 s−1) Formaldehyde appears to be a useful probe for astrochemists due to its low reactivity in the gas phase and to the fact that the 110←111 and 211←212 K-doublet transitions are rather clear.