Formaldehyde/Formalin
Summary
Formaldehyde is a chemical agent found in virtually all homes and workplaces. In addition to acting as a contact allergen, inhalation of formaldehyde can exacerbate asthma.
Epidemiology
Worldwide distribution
Formaldehyde exposure is widespread in homes, communities, and workplaces. In Denmark over a ten-year period (2007–2016), the prevalence of contact allergy to formaldehyde 1% was found to be 1.5%, while contact allergy to formaldehyde 2% was found to be 2.4%. Among patients referred for allergic contact dermatitis to an American medical center, 8.1% were allergic to formaldehyde, 7.1% were allergic to Bioban™ (a cleaning chemical), and 9.5% were allergic to other formaldehyde releasers.
In Finland, formaldehyde and formaldehyde releasers caused 5.5% of cases of occupational allergic contact dermatitis during the period from 2005–2016.
Risk factors
Occupational contact allergic dermatitis is seen in many professions, including manual labor and professional occupations.
Low-income communities are disproportionately exposed to formaldehyde; the use of low-cost building materials, including pressed wood products, puts inhabitants at an increased risk of formaldehyde exposure.
Route Of Exposure
Main
Contact.
Secondary
Inhalation.
Clinical Relevance
Allergic contact dermatitis in formaldehyde-sensitized patients is often chronic due to the ubiquitous nature of formaldehyde, and frequently presents on the hands and face where contact is most likely.
In addition to contact allergies, inhalation of formaldehyde is a potential cause of asthma, where exposure occurs primarily through inhalation, but also occurs by direct contact irritation of the respiratory tract.
Cross-Reactivity
Formaldehyde-releasing substances induce positive reactions in formaldehyde-allergic patients; In a study, 80% of formaldehyde-allergic patients had a positive patch test reaction to at least one formaldehyde releaser, most commonly benzylhemiformal. In patients sensitized to bronopol and quaternium-15, 25% and over 50% respectively also react to formaldehyde. The strongest association of sensitization is between formaldehyde and quaternium-15.
References
- Jang JH, Park SH, Jang HJ, Lee SG, Park JH, Jeong JW, et al. A Case of Recurrent Urticaria Due to Formaldehyde Release from Root-Canal Disinfectant. Yonsei Med J. 2017;58(1):252-4.
- Lam J, Koustas E, Sutton P, Padula AM, Cabana MD, Vesterinen H, et al. Exposure to formaldehyde and asthma outcomes: A systematic review, meta-analysis, and economic assessment. PLoS One. 2021;16(3):e0248258.
- Flyvholm MA, Menné T. Allergic contact dermatitis from formaldehyde. A case study focussing on sources of formaldehyde exposure. Contact Dermatitis. 1992;27(1):27-36.
- Latorre N, Silvestre JF, Monteagudo AF. [Allergic contact dermatitis caused by formaldehyde and formaldehyde releasers]. Actas Dermosifiliogr. 2011;102(2):86-97.
- Fasth IM, Ulrich NH, Johansen JD. Ten-year trends in contact allergy to formaldehyde and formaldehyde-releasers. Contact Dermatitis. 2018;79(5):263-9.
- Anderson BE, Tan TC, Marks JG, Jr. Patch-test reactions to formaldehydes, bioban, and other formaldehyde releasers. Dermatitis. 2007;18(2):92-5.
- Aalto-Korte K, Pesonen M. Patterns of positive patch test reactions to formaldehyde and formaldehyde releasers at the Finnish Institute of Occupational Health from 2007 to 2020. Contact Dermatitis. 2021;85(4):429-34.
- Tagka A, Lambrou GI, Matsopoulos GK, Fytili D, Mirkopoulou D, Katsarou A, et al. Analysis of Prevalence and Risk Factors of Contact Sensitization with respect to the Occupational Profiles in a Greek Patient Cohort: A Retrospective Analysis of a Greek Referral Centre and Future Perspectives. Biomed Res Int. 2021;2021:6672506.