Formaldehyde is a low molecular weight chemical and can elicit acute and chronic health related problems. Most of the inhaled formaldehyde is retained in the upper respiratory tract due to its extraordinary solubility. Therefore, cases of formaldehyde-induced occupational asthma are sporadic despite its widespread use in industrial processes. We herein report upon a case of occupational asthma due to formaldehyde, which was confirmed by workplace challenge including working environmental assessments, and by formaldehyde inhalation challenge using a specially designed closed-circuit apparatus. To investigate the possible involvement of an IgE-mediated mechanism, both in vitro and in vivo tests were done. IgE antibody specific for formaldehyde-human serum albumin conjugate (F-HSA) was not detected by ELISA, and no specific cutaneous reactivity to F-HSA was noted by either skin prick or intradermal test. The patient was diagnosed with formaldehyde-induced occupational asthma not associated with an IgE mediated mechanism.
Adult ; Antibodies/blood ; Asthma/*chemically induced ; Case Report ; Formaldehyde/*adverse effects/immunology ; Human ; Male ; Occupational Diseases/*chemically induced

Although formaldehyde is well known to cause type 4 hypersensitivity, immunoglobulin E (IgE)-mediated hypersensitivity to formaldehyde is rare. Here, we report a case of recurrent generalized urticaria after endodontic treatment using a para-formaldehyde (PFA)-containing root canal sealant and present a review of previous studies describing cases of immediate hypersensitivity reactions to formaldehyde. A 50-year-old man visited our allergy clinic for recurrent generalized urticaria several hours after endodontic treatment. Prick tests to latex, lidocaine, and formaldehyde showed negative reactions. However, swelling and redness at the prick site continued for several days. The level of formaldehyde-specific IgE was high (class 4). Thus, the patient was deemed to have experienced an IgE-mediated hypersensitivity reaction caused by the PFA used in the root canal disinfectant. Accordingly, we suggest that physicians should pay attention to type I hypersensitivity reactions to root canal disinfectants, even if the symptoms occur several hours after exposure.
Disinfectants/*adverse effects ; Formaldehyde/*adverse effects ; Humans ; Hypersensitivity, Immediate/*chemically induced ; Immunoglobulin E/*immunology ; Male ; Middle Aged ; Recurrence ; Skin Tests ; Time Factors ; Urticaria/*chemically induced/diagnosis ; Zinc Oxide-Eugenol Cement/*chemistry