Heavy metal — contact allergen

Nickel in the bedroom

By — 19-year firefighter and entrepreneur. Published July 2026.

Nickel is the most common cause of metal contact allergy worldwide, affecting an estimated 10-20% of women and 1-3% of men. IARC classifies nickel compounds as Group 1 (carcinogenic to humans, primarily via inhalation of nickel refinery dust) and metallic nickel as Group 2B (possibly carcinogenic). In the bedroom, nickel is present in mattress springs, metal bed frames, zippers, snaps, grommets, and jewellery worn during sleep. The carcinogenic risk applies to occupational inhalation, not to skin contact — but the allergenic risk from dermal contact is significant and widespread.

Nickel — Embr Bedroom Chemistry Atlas

At a glance

Chemical familyTransition metal — most common metal contact allergen
CAS number7440-02-0
ClassificationIARC Group 1 (nickel compounds, inhalation — carcinogenic to humans); IARC Group 2B (metallic nickel — possibly carcinogenic); EU Skin Sens. 1 (H317)
Where you encounter itMattress springs, metal bed frames, zippers, snaps, grommets, belt buckles, jewellery; stainless steel alloys; coins; some pigments
Sleep micro-environment relevanceContact allergy from nickel-releasing metal hardware in mattresses, bed frames, and bedding components. The carcinogenic risk is occupational (inhalation) and does not apply to consumer skin contact

Regulatory & certification status

European UnionREACH Annex XVII Entry 27 restricts nickel release to 0.5 µg/cm²/week from articles in prolonged skin contact (post assemblies, zippers, snaps, rivets, etc.). CLP Skin Sens. 1 (H317), Carc. 2 (H351) for metallic nickel. Regulatory — European Union authority
United StatesNo federal restriction on nickel in consumer products (unlike the EU). California Proposition 65 listed (cancer — nickel compounds). OSHA occupational exposure limits for nickel. Regulatory
CanadaNo specific consumer-product nickel release limit (unlike EU). CEPA Schedule 1 for some nickel compounds. Regulatory
InternationalIARC Group 1 (nickel compounds, inhalation) / Group 2B (metallic nickel). OEKO-TEX Standard 100 limits extractable nickel in textiles. EU Toy Safety Directive restricts nickel release in toys. Regulatory

What it is

Nickel is a silvery transition metal widely used in alloys (stainless steel, nickel-plated metals) and in many everyday objects. IARC classified nickel compounds as Group 1 (carcinogenic to humans) in 1990, based on evidence of lung and nasal sinus cancers in nickel refinery workers exposed to inhaled nickel dust and fumes. Metallic nickel was classified as Group 2B (possibly carcinogenic). The carcinogenic risk is from occupational inhalation, not from skin contact with nickel-containing objects. However, nickel is the most prevalent metal contact allergen globally — nickel allergy (allergic contact dermatitis) is extremely common, particularly in women, driven by prolonged skin contact with nickel-releasing metals in jewellery, clothing hardware, and household objects.

Where it shows up in bedding

Nickel is present in multiple bedroom components: innerspring mattress coils (steel alloy), metal bed frames and headboards, zippers on mattress covers, decorative snaps and grommets on bedding, and any metal hardware in adjustable bases. For people with nickel allergy, prolonged skin contact with nickel-releasing metal parts during sleep can trigger allergic contact dermatitis — redness, itching, and eczema at contact sites. The EU restricts nickel release from articles in prolonged skin contact under REACH Annex XVII Entry 27.

The Embr Exposure Ledger: Nickel

One chemical, several public questions, answered from independent datasets and joined here — the environment it shows up in, the body burden it carries, how it is regulated, and what actually reduces it.

This compound appears in 8 of the Embr Exposure Ledger’s 10 exposure datasets.
Is it in the air?
In U.S. outdoor air: about 0.12 in a million added lifetime cancer risk.Source: EPA AirToxScreen (2020) — modeled ambient air-toxics concentrations and risk
Is it in smoke?
Measured in the emissions of cigarette smoke, prescribed fire, residential wood smoke and wildfire. This is what the source gives off, not a level in anyone's home: it says the compound is present in that smoke, not how much of it reaches a person. What smoke leaves behind indoors.Source: US EPA, SPECIATE 5.4 — the EPA repository of source-emission composition profiles (air toxics, criteria and greenhouse pollutants)
At what level would it matter?
Published benchmarks exist: an inhalation reference concentration of 1e-05 mg/m³ (ATSDR (draft)) and a residential indoor-air screening level of 0.01 µg/m³, set on a non-cancer endpoint (hazard quotient of 1). A screening level is the concentration at which EPA would look further, not a boundary between safe and harmful. The ledger holds no measured sleeping-environment concentration for this compound, so there is nothing here to compare the benchmark against — it tells you what would matter, not what is in any room.Source: US EPA, Regional Screening Levels (RSL) Summary Table — consolidated toxicity values from IRIS, PPRTV, ATSDR, Cal EPA and OPP
Who releases it?
2,296 US facilities reported releasing it in 2024 across 49 states and territories; 1,182 Canadian facilities have reported it (1993-2024). These are self-reported quantities leaving a facility, not levels anyone encountered, and the two national programs are not added together — they use different reporting thresholds.Source: US EPA, Toxics Release Inventory (TRI) Basic Data File, 2024 reporting year; Environment and Climate Change Canada, National Pollutant Release Inventory (NPRI), releases 1993-present
Is it in me?
Measured in the U.S. population blood/urine (17-18): geometric mean 1.11 µg/L; 95th percentile 4.23 µg/L.Source: CDC, National Report on Human Exposure to Environmental Chemicals (NHANES biomonitoring)
Does the law flag it?
Listed under California Proposition 65 for cancer since 1989. Carries an EU-wide binding classification as carcinogenic (category 2). That classifies the substance itself; it does not restrict any product.Source: California OEHHA Proposition 65 List (Safe Drinking Water and Toxic Enforcement Act of 1986)Source: EU CLP Annex VI
Has a regulator acted?
Regulators have acted on products over this compound: 1 US product recall and 501 EU safety alerts. 11 involved bedding, furniture or textiles. These are actions against specific products, not a measure of the substance in general — and counts follow enforcement attention as much as they follow prevalence.Source: US Consumer Product Safety Commission (CPSC) recall databaseSource: EU Safety Gate (RAPEX), European Commission rapid alert system for dangerous non-food products

Detection and body-burden figures are occurrence data, not a personal measurement or a health diagnosis. Part of the Embr Exposure Ledger — an open, cross-dataset chemical join (download the data), reusable with attribution.

Citations

  1. IARC (1990). Chromium, Nickel and Welding. IARC Monographs Vol. 49. Source Regulatory
  2. ATSDR (2005). Toxicological Profile for Nickel. Agency for Toxic Substances and Disease Registry. Source Regulatory
  3. EU REACH Annex XVII Entry 27 — Nickel release restriction. Source Regulatory

Frequently asked questions

  • Does nickel in mattress springs cause cancer?

    No. The carcinogenic risk from nickel is specifically from inhaling nickel refinery dust in occupational settings — not from skin contact with nickel-containing metal objects. IARC Group 1 applies to nickel compounds via inhalation. The steel alloys used in mattress springs release negligible amounts of nickel and do not create inhalable dust under normal use.

  • Can mattress hardware trigger nickel allergy?

    Yes. Nickel allergy is the most common metal allergy worldwide, and prolonged skin contact with nickel-releasing metal parts in mattresses (zippers, snaps, grommets) or bed frames can trigger allergic contact dermatitis. If you have a diagnosed nickel allergy, look for nickel-free hardware or use a mattress protector that prevents direct skin contact with metal components.

Related compounds

  • Chromium — another common metal allergen and IARC Group 1 carcinogen
  • Cobalt — often co-sensitises with nickel
  • Lead — another heavy metal in household dust
  • Cadmium — a heavy metal found in some pigments

Embr is a sleep environment company researching and addressing the chemistry of the bedroom. Research and product development in progress.

Last reviewed 2026-07-07. If you find a factual error, contact us.