No single heavy metal limit applies to all dyes and pigments. The limit depends on what the colourant goes into and where the product is sold. A pigment in a toy, a dye in a T-shirt and a colour in food packaging face different rules.
Start by naming the end use and the market, then find the rule or brand list that applies, then ask the supplier for test results against it.
Heavy metals in colourants usually come from raw materials, catalysts, metal-bearing intermediates or worn equipment. That is why two makers of the same pigment can show quite different results, and why one good test does not prove every lot is clean.
Where limits come from
- Textile restricted substance lists, such as the ZDHC MRSL and brand lists, set limits for metal impurities in dyes and for extractable metals in finished goods.
- EU packaging law limits the combined content of lead, cadmium, mercury and hexavalent chromium in packaging and its parts, including inks and pigments, to 100 mg/kg.
- Toy safety rules, including the EU's migration limits tested by EN 71-3, set limits on metals that can leach from toy materials.
- Food contact rules in many countries set purity criteria for colourants in plastics, inks and coatings that touch food.
- Cosmetic and food colour rules set their own purity criteria per colour, covering metals such as arsenic, lead, mercury and cadmium.
Metals that come up most
Lead, cadmium, mercury, hexavalent chromium and arsenic are restricted almost everywhere. Antimony, cobalt, copper, nickel and others come up in some textile and toy rules.
Some colourants contain a metal by design. Phthalocyanines contain copper, and metal-complex acid dyes contain chromium or cobalt. Rules usually treat that bound metal differently from free or extractable metal, but you need to check the exact wording. Pigments based on lead chromate or cadmium are now heavily restricted in many markets.
Read what acid dyes are used for if you buy metal-complex dyes.
How to manage it
- Write the applicable rule or brand list into your specification, with the limit for each metal.
- Ask for a test report from an accredited laboratory that states the method, such as ICP analysis after digestion or a migration test.
- Check that the method matches the rule, since total content and migration are different measurements.
- Retest when the supplier changes a raw material or a production site.
- Confirm the rule with your regulator or a testing body, since limits are revised and differ by country.
Next step
We collect test reports, check they match the product and lot, and have samples tested independently before shipment. Read how to read a lab certificate for the details to check. To begin, book a free sourcing review.