Formaldehyde is a well-known sensitizer, with approximately 2.5% of patients testing positive with the standard allergen series from the Portuguese Study Group on Contact Dermatitis. In a study of nurses with suspected occupational dermatoses, 20.6% had positive patch tests indicating contact allergy to formaldehyde [3], the same professional category as the patient in this case.

The increased use of gloves following the introduction of universal infection control precautions has been linked to a concomitant rise in glove-related allergic reactions [5].

In the case presented, despite the nurse's longstanding latex allergy and the implementation of preventive measures in her workplace, the introduction of a new glove brand triggered dermatological symptoms confined to her hands. This suggests sensitization to new agents in the gloves, with occupational exposure as a key contributing factor [3,6,7]. Symptoms resolved upon discontinuation of Brand B gloves [10]. However, the negative patch test results for Brand B gloves suggest that other occupational or local factors (e.g., cosmetic use, skin hydration, mechanical friction, or differences in skin characteristics between the hands and the test site) may have contributed to symptom development [3,6,7].

It is hypothesized that the worker may have developed a formaldehyde allergy following prolonged contact (exceeding the manufacturer-recommended exposure time) with products containing the chemical. Brand B gloves offer level 3 out of 6 protections, with a maximum exposure time of 60 minutes. However, based on clinical history, this hypothesis is unlikely, as her job does not involve handling formaldehyde- containing products.

Another possibility, discussed collaboratively between Occupational Medicine and Dermatology, is that the gloves themselves were contaminated with formaldehyde during manufacturing, despite no mention of this chemical in the manufacturer's technical information. A Swedish study by the Department of Occupational and Environmental Dermatology evaluated nine glove types for formaldehyde presence, finding positive results in six gloves using a semi-quantitative chromotropic method. Most formaldehyde was detected on the glove's inner surface [3]. Such contamination could explain the nurse's symptoms after contact with Brand B gloves.

Additionally, irritant factors associated with glove use, such as mechanical friction or skin moisture, may have exacerbated the condition, creating circumstances not replicated during patch testing. The potential role of cosmetics containing formaldehyde or formaldehyde-releasing agents also cannot be excluded. There is no information on which glove surface was in contact with the skin during testing.

Regardless of the cause, the worker, already restricted from contact with latex-containing materials, was further limited from using Brand B gloves. The occupational physician reported a suspected case of occupational disease, "Allergic Contact Dermatitis to Formaldehyde," under code 33.01 of the Occupational Diseases List, which includes "Physical, chemical, and biological agents, allergens, or skin irritants not included in other categories." The case is currently under review.