Formaldehyde allergy

What is formaldehyde and where is it found?

Formaldehyde is a chemical that is used widely across many products in our environment. It would be difficult to list all the possible sources of formaldehyde; the table below shows some of the more common sources of formaldehyde exposure.

What are the reactions to formaldehyde?

Reactions to formaldehyde depend on the type of exposure that has occurred. Formaldehyde is not only a sensitiser but also a potent primary irritant. Exposure to formaldehyde gas may cause burning sensations in the eye, nose and throat, skin rashes, tightness of the chest and wheezing, fatigue and headaches. These symptoms may be a result of a primary irritant effect or an allergic sensitisation to formaldehyde.

Frequent or prolonged exposure may cause hypersensitivity, leading to the development of allergic contact dermatitis. Formaldehyde was declared the Contact Allergen of the Year for 2015 by the American Contact Dermatitis Society (ACDS).

Allergy to formaldehyde may occur through skin formaldehyde-containing products or with clothing made from fabrics containing formaldehyde. Dermatitis caused by clothing tends to affect parts of the body where there is the greatest friction between the skin and fabric, for example, "trouser dermatitis" is usually apparent on the inner thighs, gluteal folds and backs of the knees. Sweating may also be a factor in causing allergic dermatitis as sweat or sebum appears to leach free formaldehyde from formaldehyde resins. Individuals sensitive to formaldehyde are not necessarily hypersensitive to formaldehyde resins. Clothing dermatitis is reported to affect women more than men.

In highly sensitive individuals, contact with minute amounts of formaldehyde, or being in a room where a bottle of formaldehyde may have been open previously thus leaving residual gas, can cause dermatitis.

Patch tests 

Am I allergic to formaldehyde?

Formaldehyde allergy is diagnosed from the clinical history and by performing patch tests.

Patch testing of formalin (40% solution of formaldehyde gas) is performed using a 2% aqueous solution of formalin. Some investigators have stated that 75% of positive patch tests have no clinical significance and only 20% of these can be related to actual instances of formaldehyde dermatitis. Formaldehyde 2% in aqueous solution and 4-tert-butylphenol formaldehyde resin (PTBP) 1% in petrolatum, for example, are present in various baseline series of patch test allergens including the European Baseline Series.

The diagnosis of clothing dermatitis due to free formaldehyde can only be confirmed if the following standard criteria are fulfilled. In some cases, clothing dermatitis may not be a problem, even if the suspected fabric tests positive for free formaldehyde and an individual has a positive patch test reaction to 2% formalin.

Formaldehyde clothing dermatitis — criteria to fulfil:

• Suspected fabric shows the presence of free formaldehyde
• The patient shows a positive patch test reaction to 2% formalin
• Formaldehyde resin impregnated fabric show a positive patch test reaction — the piece of fabric tested should have been worn and subjected to sweat, sebum and friction
• Wearing the fabric causes a clinical allergic contact dermatitis.

Patch testing of products for formaldehyde resins is performed using 10% urea formaldehyde in petrolatum, 10% melamine formaldehyde in petrolatum and 1% other formaldehyde resins in petrolatum or isopropyl alcohol.

Self-testing a product for formaldehyde should be done only with products that are designed to stay on on the skin such as cosmetics and lotions. Apply a small amount of the product to a small tender area of skin such as the bend of your arm or neck. Examine the area each day for several days, and if no reaction occurs, the product is most probably suitable for you to use.

Treatment of contact dermatitis due to formaldehyde exposure

If you are diagnosed with formaldehyde allergy then if at all possible avoid exposure to formaldehyde containing products, otherwise take means to reduce potential exposure.

Once dermatitis appears on the skin, treatment is as for any acute dermatitis/eczema, i.e. topical corticosteroids, emollients, treatment of any secondary bacterial infection (Staphylococcus aureus), etc.

What should I do to avoid formaldehyde allergy?

It is difficult to avoid all exposure to formaldehyde because it is normally present at low levels (usually <0.03 ppm) in both indoor and outdoor air. For most people, low-level exposure (up to 0.1 ppm) does not cause any problems. Methods to avoid or minimise exposure are described in the table below.

Methods to avoid or minimise exposure to high levels of formaldehyde:

• Wear clothing made of 100% cotton, silk, polyester, nylon or acrylic; these fabrics generally contain less formaldehyde and are usually well tolerated by sensitive individuals
• Avoid all clothing made with fabrics that have been treated with formaldehyde (see above)
• In general, machine wash all new clothing and bedding in hot, soapy water several times before use
• Purchase furniture made of pressed wood products only if the surfaces and edges are laminated or coated
• Occupational exposure can be reduced by identifying potential sources of exposure (material safety data sheets should be available to employees) and taking precautions to minimise exposure by wearing suitable protective garments
• To reduce the formaldehyde content in the air, increase ventilation by opening doors and windows and installing exhaust fans in closed areas
• Read product labels and avoid not only formaldehyde itself but also formaldehyde-releasing preservatives. Some of these are known by the following names:
  • Quaternium-15
  • 2-bromo-2-nitropropane-1,3-diol (bronopol)
  • Imidazolidinyl urea
  • Diazolidinyl urea

Alternative names for formaldehyde

Formaldehyde is also known by several other names. These include:

• Formalin
• Methanal
• Methyl aldehyde
• Methylene oxide
• Morbicid acid
• Oxymethylene.

Avoid all of these. At work, request a material safety data sheet to help identify potential sources of exposure.

Further information

Formula: CH₂0

CAS number: 50-00-0

Cross-reactions: possibly glutaraldehyde

Appearance: clear, colourless liquid

Sensitiser: free formaldehyde, formaldehyde resins

Patch Test:

2% aqueous solution of formalin (40% solution of formaldehyde gas)

10% urea formaldehyde in petrolatum

7-10% melamine formaldehyde in petrolatum

1% other formaldehyde resins in petrolatum or isopropyl alcohol.

10% toluenesulfonamide (tosylamide) formaldehyde resin in petrolatum