13 sourced data visualisations on nickel allergy, piercing safety, jewellery materials, tattoo removal and EU regulation. Every chart links to its primary source. Free to embed on your own site with attribution, under CC BY 4.0.
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Nickel & allergy
Nickel sensitisation by group
Nickel is the single most common contact allergen, and prevalence is several times higher in women than in men (unselected general-population data, Glostrup).
Nickel content of common body-jewellery materials (% by weight)
Implant-grade titanium and non-metallic polymers carry effectively no nickel; stainless steel relies on a passive layer to stay compliant; nickel-silver alloys are unsuitable for piercings.
Nickel content by weight, common body-jewellery materials
Implant-grade titanium and BioFlex® PP-R are effectively nickel-free; 316L surgical steel is a nickel-bearing alloy that relies on a passive layer to stay within release limits.
The material left against the gum drives the damage. Rigid metals caused several times more recession than flexible polymer in a scoping review of oral piercing.
Nickel allergy in women 18–35, before vs after the EU Nickel Directive
Limiting how much nickel an item may release, rather than how much it contains, cut prevalence by roughly a third in the most-exposed group. Enforcement is the remaining gap: about a quarter of earring posts still exceeded the limit in a 2025 review.
Jewellery worn in a fresh piercing must meet a limit more than twice as strict as the general skin-contact rule, because a healing channel is an open wound.
Ear and nose dominate non-earlobe piercings; the slower-healing cartilage, oral and surface sites are where jewellery material choice most affects the outcome.
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