Cobalt allergy in hard metal workers.

Area of Science:

• Occupational Dermatology
• Toxicology
• Immunology

Background:

• Hard metal, commonly used in industrial applications, contains a significant percentage of cobalt (approximately 10%).
• Occupational exposure to environmental substances is a concern for workers handling such materials.

Purpose of the Study:

• To investigate the prevalence and characteristics of cobalt allergy among hard metal workers.
• To identify risk factors associated with cobalt sensitization in this occupational cohort.

Main Methods:

• A cohort of 853 hard metal workers underwent patch testing with environmental substances.
• Initial patch tests with cobalt chloride were followed by secondary serial dilution tests to confirm allergic reactions.
• Patient history, including hand eczema and previous skin conditions, was collected.

Main Results:

• 62 out of 853 workers showed positive initial patch tests to cobalt chloride.
• Reproducible allergic reactions to cobalt were confirmed in 39 individuals (9 men, 30 women) via serial dilution tests.
• A history of hand eczema was prevalent in individuals with reproducible cobalt allergy (36/39).
• Hand etching and grinding activities were identified as high-risk occupations for cobalt sensitization, particularly among women.
• 24 individuals presented with isolated cobalt allergy, likely due to hard metal work.
• Women with simultaneous nickel allergy were likely sensitized to nickel prior to employment, with subsequent cobalt sensitization from hard metal work.

Conclusions:

• Occupational exposure to cobalt in hard metal workers can lead to allergic contact dermatitis.
• Traumatic occupational activities leading to irritant contact dermatitis, or pre-existing allergies/atopy, are likely prerequisites for developing cobalt allergy.
• Risk management strategies should consider specific work processes and pre-existing skin conditions in hard metal workers.