Cadmium legislation update

Explaining current worldwide legislative requirements for cadmium and cadmium compounds.

by Martin Heels

In its elemental state, cadmium is an extremely toxic metal that is used in electroplating, inside batteries, in electrical contacts and within some industrial paints. Cadmium compounds have been historically used in the footwear industry as pigments and polymeric stabilisers. However, their use has been restricted since 1992 within Europe through a European Directive and in America via State laws. These restrictions are due to numerous health concerns surrounding cadmium and its compounds, and more recent evidence of these has resulted in the May 2011 publication of European Regulation 494/2011.
The dangers of cadmium

Although some cadmium can be absorbed through the skin, the greatest risk of exposure to cadmium occurs when it is ingested through food or inhaled via tobacco smoke. Exposure to cadmium fumes or dust can cause respiratory problems, which can be fatal. Significant amounts in the body can lead to poisoning and damage to the liver and kidneys. Within the body, cadmium can attack bones, causing them to become soft and increasing the risk of fractures. Cadmium accumulates in the kidneys, where it damages the filtering mechanisms and causes essential protein and sugars to be removed from the blood. Cadmium is a suspected carcinogen, and can cause brain damage in very young children.

Cadmium in the environment

With footwear, cadmium primarily becomes a danger after the lifetime of the product, when materials are disposed of in landfill or the ashes after incineration are buried. Cadmium is easily absorbed into organic matter in soils and can, therefore, be taken up by plants (including cereal crops, fruit and vegetables) and invertebrates. The cadmium then enters the food chain through cattle and other animals that depend on these for food. This presents a danger to both these animals, and to the species that subsequently eat them – including humans, who are at the top of the food chain.

Cadmium in footwear

Some cadmium compounds are very brightly coloured, and have other properties that lead to their use in solings and coated fabrics. Cadmium pigments disperse well in polymers and have excellent heat stability. They are insoluble in organic solvents and, hence, are known for being particularly colour fast. These properties make the pigments particularly suitable for use in polymers that are processed at high temperatures, such as acrylonitrile butadiene styrene (ABS), high-density polyethylene and other thermoplastic polymers. Pigments are usually incorporated into plastics in proportions of 0.01 to 0.75 per cent – 100 to 7,500 parts per million (ppm). As well as in plastics, yellow, orange, red and maroon pigments containing cadmium have been used in ceramics, glasses and specialist paints.

Cadmium compounds have also been used as stabilisers in PVC materials, selected for their excellent heat stability and weather resistance. Generally, the cadmium has been present as a stearate or laurate soap, combined with barium or lead compounds to further improve the property of the PVC. Barium and zinc stabilisers are now widely used as replacements.

There are several legal requirements around the world to restrict the amount of cadmium as a result of the severe health concerns.

American regulations

The CONEG (Coalition of Northeastern Governors) Regulations have limited the maximum amount of four metals (lead, mercury, hexavalent chromium and cadmium) in packaging and packaging components. The sum of these four metals should not exceed 100ppm. The Californian law Proposition 65 has listed cadmium compounds as potential carcinogens and reproductive toxins, so consumer goods containing cadmium on the market in the State require general warning labels, such as ‘certain cadmium compounds are known to the State of California to cause cancer, birth defects and other reproductive harm’.

There are also laws in specific US States that limit the total amount of cadmium in children’s jewellery. California, Connecticut, Illinois, Maryland and Minnesota have current or pending legislation restricting the amount of extractable cadmium. This is a similar procedure to that required by the European Toy Safety Directive, which determines the amount of cadmium and seven other heavy metals that could be released into stomach acid if the item was swallowed. The maximum limit for extractable cadmium in toys is 75ppm, but this will be reduced to 23ppm when the chemical requirements of the latest Toy Safety Directive 2009/48/EC are enacted in July 2013. This lower concentration is based on recent research into safe daily intake levels of each of the elements listed in the directive.

European regulations

European Regulation 494/2011 – enacted from January 2012 – amended the cadmium entry in REACH Annex XVII, which itself succeeded the original Cadmium Directive 91/338/EEC. The maximum amount of cadmium permitted has remained at 0.01 per cent (100ppm), although the list of synthetic organic polymers (plastics) covered by the regulation has increased from 16 to 19.

There are some exemptions when PVC has been recycled for use in specific construction products, and these products must be indelibly marked as containing recovered PVC or include a new pictogram.

Publishing Data

This article was originally published on page 36 of the April 2012 issue of SATRA Bulletin.

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