Physical and Chemical Properties of Formaldehyde

Formaldehyde is the simplest type of aldehydes, soluble in water, ethanol, and chloroform. In addition, formaldehyde can be mixed with acetone, benzene, and diethyl ether.

The formaldehyde molecule consists of a central carbon atom that is connected by a single bond to two hydrogen atoms and by a double bond to one oxygen atom.

How is Formaldehyde Produced?

Formaldehyde is produced naturally within cells as well as in industry. Each of these methods is mentioned below.

Endogenous Production of Formaldehyde

Endogenous formaldehyde is produced through various pathways, including amino acid metabolism and methanol and histone demethylation. Mammals produce formaldehyde in amounts that can have lethal effects. The body has detoxification systems to neutralize the effects of formaldehyde, the first and most important of which is an enzyme called ADH5. Another vital secondary mechanism for removing formaldehyde from the body is the cross-linking repair pathway of DNA Fanconi anemia (FA).

Exogenous Production of Formaldehyde

As a gaseous chemical compound, formaldehyde cannot be used in pure form and without water in cosmetic products. Instead, it is usually used in the form of an aqueous solution, formalin. In industry, formalin is primarily produced from methanol. To produce formaldehyde, a mixture of methanol and steam is passed over a catalytic bed, resulting in the oxidation of methanol. Since this process is highly exothermic, the gas flow is rapidly cooled after passing over the catalytic bed to prevent thermal decomposition.

Formaldehyde in its pure gaseous form is very unstable; for this reason, it reacts in an absorption column with water, resulting in the formation of methylene glycol. This substance cannot exist as a separate commercial product and instead is produced as part of an aqueous formalin solution.

Methylene glycol exists only in aqueous solutions and is stabilized in these solutions through hydrogen bonding interactions with water molecules. The high solubility of formaldehyde in water can be attributed to its rapid hydration to methylene glycol. The equilibrium between methylene glycol and formaldehyde, especially at room temperature and at pH neutral, strongly favors methylene glycol.

Applications of Formaldehyde

Formaldehyde and its derivatives are used as preservatives to extend the shelf life of various products (their longevity on store shelves); including cosmetic products, some food items, and various household products such as disinfectants and medicines. Formaldehyde is also used in the production of fertilizers, paper, plywood, and urea-formaldehyde resins.

Safety of Formaldehyde in Cosmetic Products

Based on a substantial body of existing evidence, the Cosmetic Ingredient Review Expert Panel, known as the (Cosmetic Ingredient Review Expert Panel) emphasizes that exposure to formaldehyde gas can lead to nasopharyngeal or throat and nasal cancers (NPCs). Despite the debate and disagreement regarding the dose-response relationship necessary for developing NPC, the panel has maintained its view that such cancers can be caused by formaldehyde at high doses.

Based on the available data, the panel concluded that the presence of formaldehyde/methylene glycol in products that enhance nail strength poses no risk. Other data showed that the current concentration of formaldehyde in these products is about one to two percent (with one tested product having a level of 2.2%) which is considered an appropriate amount. Panel experts believe that at room temperature, due to the rapid reaction of this substance with the nail surface, there is no risk of sensory irritation to the eyes, nose, or throat for users. Furthermore, according to the guidelines for nail strengthening products, this product should not come into contact with the skin and its use is limited to the nail until it is completely dry.

Is Formaldehyde Safe?

The panel of experts concluded that the use of formaldehyde and methylene glycol in cosmetic products is safe as long as they are used at the minimum necessary levels. However, the concentrations of formalin, formaldehyde, and methylene glycol should not exceed 0.2 percent (w/w), 0.074 percent (w/w), and 0.118 percent (w/w) respectively. Additionally, the panel considers the presence of formaldehyde in nail strengthening products at the levels that have been used so far to be safe. However, hair smoothing products containing formaldehyde at current concentrations are considered dangerous.

Final Words

The use of formaldehyde and methylene glycol in cosmetics is safe, provided that the established thresholds for their safe use are adhered to. Furthermore, the use of these compounds in nail strengthening products at current concentrations and usage amounts poses no risk. However, it should be noted that these products should never come into contact with the skin. Nevertheless, to date, concentrations of formaldehyde and methylene glycol have been used in hair smoothing products that are considered hazardous.

Formaldehyde

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