Formaldehyde

Our bodies produce modest amounts of formaldehyde naturally. Fertiliser, paper, plywood, and urea-formaldehyde resins are all made with it. It’s also employed as a preservative in several meals and a variety of household products like antiseptics, medications, and cosmetics. Many additional minerals and chemical compounds require formaldehyde as a precursor. The installed capacity for formaldehyde manufacturing was estimated to be 8.7 million tonnes per year in 1996. It is mostly used to make industrial resins, such as particle board and coatings. Formaldehyde, solutions (formalin) (corrosive) is a white liquid with a strong, unpleasant odour. Contains 37-50 percent formaldehyde by mass, as well as various amounts of methanol, which is added to avoid formaldehyde polymer precipitation.

Forms of formaldehyde:

Because it takes on multiple different forms, formaldehyde is more difficult than many other simple carbon molecules. These compounds are frequently interchangeable and interconvertible.

• Molecular formaldehyde.A colourless gas with an odour that is strong and unpleasant. It is stable at around 150 °C, but when condensed to a liquid, it polymerizes.
• 1,3,5-Trioxane is a chemical compound having the formula (CH2O)3. It’s a white substance that dissolves in organic solvents without degrading. It’s a molecular formaldehyde trimer.
• The chemical compound paraformaldehyde has the formula HO(CH2O)nH. It’s a white solid that won’t dissolve in most liquids.
• Methanediol, with the formula CH2(OH)2.Depending on the concentration and temperature, this molecule also occurs in equilibrium with a variety of oligomers (short polymers). “100% formalin” is a saturated water solution containing around 40 percent formaldehyde by volume or 37 percent by mass.

To prevent oxidation and polymerization, a tiny amount of stabiliser, such as methanol, is frequently added. In addition to different metallic contaminants, commercial-grade formalin may contain 10–12 percent methanol.Following a prior trade name, “formalin,” “formaldehyde” was first used as a generic trademark in 1893.

• Main forms of formaldehyde

Monomeric formaldehyde (subject of this article).

Trioxane is a stable cyclic trimer of formaldehyde.

Paraformaldehyde is a common form of formaldehyde for industrial applications.

Methanediol, the predominant species in dilute aqueous solutions of formaldehyde.

Occurrence of formaldehyde:

Up to 90% of the total formaldehyde in the environment comes from processes in the upper atmosphere. In forest fires, automobile exhaust, and tobacco smoke, formaldehyde is an intermediary in the oxidation (or burning) of methane and other carbon molecules. It becomes part of smog when it is formed in the atmosphere by the action of sunlight and oxygen on atmospheric methane and other hydrocarbons. In addition, formaldehyde has been discovered in space.In living organisms, formaldehyde and its adducts are abundant. It is produced through the metabolism of the amino acids serine and threonine and is detected in the blood of humans and other primates at amounts of about 0.1 millimolar.

Experiments in which animals are exposed to an environment containing isotopically labelled formaldehyde have shown that the bulk of formaldehyde-DNA adducts identified in non-respiratory tissues come from endogenously generated formaldehyde, even in purposely exposed animals.

Because it is broken down within a few hours by sunlight or microorganisms present in soil or water, formaldehyde does not accumulate in the environment. Formaldehyde is swiftly metabolised by humans and converted to formic acid, thus it does not accumulate in the body.

Synthesis and industrial production:

Laboratory synthesis:

Aleksandr Butlerov (1828–86), a Russian scientist, first reported formaldehyde in 1859. A mixture of methyl alcohol vapours and air is passed through platinized asbestos or a copper or silver catalyst at 300 degrees Celsius to produce formaldehyde in the laboratory. Set up the instrument in the proper location and configuration. A suction pump is used to suck air through the methyl alcohol solution.

Industry:

The catalytic oxidation of methanol produces formaldehyde, which is used in industry. Silver metal or a combination of iron and molybdenum or vanadium oxides are the most popular catalysts.

2 CH3OH + O2 → 2 CH2O + 2 H2O

Typically, the silver-based catalyst acts at a higher temperature, at 650 °C. On it, two chemical reactions produce formaldehyde at the same time: the one depicted above and the dehydrogenation reaction:

CH3OH → CH2O + H2

Although formaldehyde might theoretically be produced by oxidising methane, this route is not commercially practical since methanol is more easily oxidised than methane.

What are the health effects of formaldehyde exposure in the short term?

When formaldehyde levels in the air exceed 0.1 parts per million, some people may have watery eyes, burning sensations in the eyes, nose, and throat, coughing, wheezing, nausea, and skin irritation. Some people are extremely sensitive to formaldehyde, while others are unaffected by the same amount of exposure.            

Is formaldehyde a carcinogen?:

Although the short-term health effects of formaldehyde exposure are widely understood, nothing is known regarding the long-term impacts. In 1980, laboratory tests revealed that formaldehyde exposure could cause nose cancer in rats. This discovery raised the possibility that formaldehyde exposure could cause cancer in humans as well. Under very high or continuous exposure, the US Environmental Protection Agency (EPA) classified formaldehyde as a possible human carcinogen in 1987. Since then, some human research has revealed that formaldehyde exposure is linked to specific cancer types. Formaldehyde is classified as a human carcinogen by the International Agency for Research on Cancer (IARC).

Conclusion:

To reduce formaldehyde exposure in the home, the EPA recommends using “exterior-grade” pressed-wood products. Because they include phenol resins rather than urea resins, these goods generate less formaldehyde. (Pressed-wood products are not the same as pressure-treated wood products, which contain chemical preservatives and are designed for outdoor usage.) Buyers should inquire about the formaldehyde level of pressed-wood items, such as building materials, cabinetry, and furniture, before purchase. Formaldehyde levels in houses can also be lowered by using air conditioners and dehumidifiers to ensure appropriate ventilation, moderate temperatures, and lower humidity levels.