Physical and Chemical Properties of Formaldehyde

Formaldehyde, being the simplest form of aldehyde, is soluble in water, ethanol, and chloroform. Additionally, formaldehyde can be mixed with acetone, benzene, and diethyl ether.

The formaldehyde molecule features a central carbon atom bonded by a single bond to two hydrogen atoms and by a double bond to one oxygen atom.

How is Formaldehyde Produced?

Formaldehyde is produced not only industrially but also naturally within cells. Each of these methods is described below.

Endogenous Production of Formaldehyde

Endogenous formaldehyde is produced through various pathways, such as amino acid metabolism, methanol, and histone demethylation. Mammals produce formaldehyde in quantities that may have lethal effects. The body has detoxification systems to mitigate the effects of formaldehyde, with the first and most important being an enzyme called ADH5. Another essential secondary mechanism for eliminating formaldehyde from the body is the DNA cross-link repair pathway associated with Fanconi anemia (FA).

Exogenous Production of Formaldehyde

As a gaseous chemical compound, formaldehyde cannot be utilized in its pure form and without water in cosmetic products. Instead, it is usually used in an aqueous solution known as formalin. In industry, formalin is primarily produced from methanol. To fabricate 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, to prevent thermal degradation, the gas flow is swiftly cooled after passing over the catalytic bed.

Formaldehyde in its pure gaseous state is extremely unstable; consequently, it reacts in an absorption column with water, leading to the generation of methylene glycol. This substance cannot exist as a standalone commercial product and is instead produced as part of an aqueous formalin solution.

Methylene glycol exists solely 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, particularly at room temperature and in pH neutral conditions, strongly favors methylene glycol.

Applications of Formaldehyde

Formaldehyde and its derivatives serve as preservatives to enhance the shelf life of various items (their storage duration on store shelves); including cosmetic products, certain food items, and a range of household products such as disinfectants and medications. Formaldehyde is also applied in the fabrication of fertilizers, paper, plywood, and urea-formaldehyde resins.

Safety of Formaldehyde in Cosmetic Products

According to a significant body of evidence, the Cosmetic Ingredient Review Expert Panel, known as the PANEL, underscores that exposure to formaldehyde gas may result in nasopharyngeal or throat and nasal cancer (NPCs). Despite the ongoing discourse and disagreement regarding the dose-response relationship required for the development of NPC, the panel has upheld its stance that such cancers can arise from high doses of formaldehyde.

The panel has concluded, based on the information available, that the presence of formaldehyde/methylene glycol in products that strengthen nails poses no risk. Other data indicated that the current concentration of formaldehyde in these products ranges from about one to two percent (with one tested product having a concentration of 2.2%), considered an appropriate level. Panel experts assert that at room temperature, due to the rapid reaction of this substance with the nail's 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 contact the skin, and its application is limited to the nail until it is fully dry.

Is Formaldehyde Safe?

The expert panel has concluded, after reviewing available data, that the use of formaldehyde and methylene glycol in cosmetic products is safe, as long as they are used in minimal amounts. 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. Moreover, the panel considers the presence of formaldehyde in nail-strengthening products used at previously established levels to be safe. Nonetheless, hair smoothing products containing formaldehyde at existing concentrations are regarded as hazardous.

Final Words

The use of formaldehyde and methylene glycol in cosmetics is safe, provided that established thresholds for their safe use are adhered to. Furthermore, the use of these compounds in nail-strengthening products at current concentrations and usage levels does not pose any risk. It is crucial to emphasize that these products should not come into contact with the skin at all. Nevertheless, it should be recognized that the concentrations of formaldehyde and methylene glycol employed in hair smoothing products up to now are deemed hazardous.

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