Regulatory limits on nickel exposure may not sufficiently protect against allergic reactions

Existing regulatory limits on nickel exposure may not sufficiently protect against allergic reactions in sensitized individuals, according to a study. Even at concentrations deemed safe by current standards, some nickel-allergic individuals exhibited clinical reactions, indicating a potential gap in consumer protection.

Conducted on both nickel-allergic individuals and healthy controls, participants underwent patch testing with varying concentrations of nickel sulphate, with a follow-up after 3-4 weeks.

Results showed that even within the regulatory limits set by European standards, some nickel-allergic individuals exhibited clinical reactions upon re-exposure to nickel. Notably, 15% of participants experienced adverse reactions to doses as low as 0.2/0.5 μg/cm2, demonstrating the potential inadequacy of current regulations in protecting sensitive individuals.

Analysis of skin biopsies revealed immune activation in response to nickel re-exposure, characterized by the up-regulation of cytokines and chemokines. Surprisingly, even in cases where no clinical reactions were observed, significant differential expression of immune-related genes was noted, suggesting subclinical immune responses to low-dose nickel exposure.

Healthy controls also exhibited some immune response to nickel re-exposure, albeit to a lesser extent compared to nickel-allergic individuals.

Reference
Wennervaldt M, Vaher H, Ahlström MG, et al. Subclinical immune responses to nickel in sensitized individuals-a dose-response study. Contact Dermatitis. 2024 Apr 5. doi: 10.1111/cod.14549. Epub ahead of print. PMID: 38577784.