lunes, 1 de abril de 2019

Formaldehyde Allergy

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By Liji Thomas, MDReviewed by Susha Cheriyedath, M.Sc.

Formaldehyde is a ubiquitous chemical agent, found both outdoors and indoors, as part of the occupational and residential environment. Formaldehyde is an extremely irritant chemical, as well as a primary skin sensitizer. Thus, it is capable of causing both irritant contact dermatitis and immediate or delayed anaphylactic reactions. Formaldehyde inhalation can also precipitate the onset of asthma. Formaldehyde allergy is especially common among healthcare workers.

A laboratory specimen of a snake preserved in a solution of formaldehyde (methanol).

Image Copyright: Signature Message / Shutterstock

Sources of Formaldehyde

Formaldehyde is an ingredient of some dental materials such as filling materials, sealers and cements, as well as the newer polymers. Industrial applications include the manufacture of resins containing formaldehyde, such as melamine formaldehyde, urea-formaldehyde (binder for plywood and particle-board processing in the wood industry), and phenol formaldehyde. New homes are likely to have a higher concentration of formaldehyde in the air, as it is released from the new wood and fabrics used, and the levels drop over time. Higher temperatures and humidity can cause increased levels of formaldehyde emission.

Textile manufacturers use formaldehyde resins to improve fire-retarding properties, water-repelling abilities, stiffness, and no-wrinkle capabilities. Many sanitary products and paper products such as paper towels also use formaldehyde. Foundries, ink, and dye production are other end-users. It is also found in many adhesives, paints, dyes, and cleaning fluids. Formaldehyde-based disinfectants, embalming fluids and preservatives are liable to cause formaldehyde allergy in workers such as those in hospitals, dental units, veterinary hospitals, and laboratories.

Formaldehyde is also found in rainwater and surface water, making its way into soil and foods. It is also found in the air, in tobacco smoke, in certain cosmetics, and in detergents. It reaches the air via automobile exhaust fumes from vehicles without catalytic converters, or from any other plant which burns fossil fuels, including energy plants. Forest fires and waste incinerators also give off formaldehyde.

Symptoms of Formaldehyde Allergy

Formaldehyde causes allergic contact dermatitis, usually on parts of the body that experience a lot of friction. Thus “trouser dermatitis” may occur on the inner side of the thighs, the folds behind the knee and the gluteal folds. This is likely to be due to the accumulation of sweat which leaches out more formaldehyde from the compounds in contact with the skin, in addition to the friction. Women are more often affected by this condition than men.

In cases of formaldehyde sensitivity, contact with very small amounts of formaldehyde, even through the air, can precipitate dermatitis.

Diagnosis and Treatment

The diagnosis of formaldehyde sensitivity is based on the symptoms and signs and a patch test using 2% formalin in aqueous solution. However, some studies have shown that the correlation between test positives and true formaldehyde allergy is as low as 20%. Additional testing is required to identify clothing dermatitis caused by formaldehyde allergy, such as confirming free formaldehyde in the fabric. Patch testing is performed using 10% melamine formaldehyde in petrolatum, 10% urea formaldehyde in petrolatum, and 1% other formaldehyde resins in isopropyl alcohol or petrolatum for allergies involving these compounds.

Treatment of formaldehyde allergy involves the use of local emollients to soothe inflammation, topical corticosteroids to reduce allergic reactions in the affected skin, and treatment of associated infection. Prevention of future allergic reactions to formaldehyde depends on avoiding exposure to formaldehyde, or, if that is impossible, minimizing exposure by various methods such as the use of cloth made of 100% cotton, silk, polyester, or nylon, and ensuring that the cloth does not contain formaldehyde . Washing all new fabrics in warm, soapy water many times before use helps reduce formaldehyde emissions. Make sure that the edges of furniture are coated or laminated, if made of pressed wood. In the workplace, ensure proper ventilation and use protective garments to minimize contact or exposure to formaldehyde.