The year you had your ears pierced shows up in the nickel allergy data

Not folklore and not my claim — this is what the patch-test literature reports.

Denmark began regulating consumer nickel exposure in 1990, four years before the EU Nickel Directive. In a Danish doctoral evaluation of that intervention, women pierced before 1990 showed significantly higher prevalence of nickel allergy and dermatitis than women pierced after.

The same pattern at population level:

A systematic review of 46 European studies found prevalence in women aged 18–35 fell from 19.8% to 11.4% after the Directive, and in female dermatitis patients aged 17 and under from 29.2% to 14.3%.

In southern Sweden, across 18,264 patch tests from 1995 to 2016, prevalence in females aged 6–30 fell from 33.4% to 19.1%. In males of the same age, 5.9% to 2.1%.

Piercing is the exposure the whole regulation was built around, which is why the date sits in the data.

It has not gone away — the review put it at 8–18% of the general population, and higher in southern than northern Europe.

Via PubMed: Thyssen, Contact Dermatitis 65 Suppl 1 (2011); Ahlström et al., Contact Dermatitis 77(4) (2017); Rosholm Comstedt et al., Contact Dermatitis 82(4) (2019).

Kept by KREMAGE, the wandering portal — entry 021.