Cadmium (Cd) based systems have been available for many years due to their excellent performance qualities. However, in the European Union area, their use was phased out voluntarily as part of the industry’s Voluntary Commitment of 2000 due to concerns about toxicity and possible accumulation in the body.
Cadmium was used in the form of a stearate or laurate for stabilising PVC and was almost invariably combined with a similar barium ester as well as a lead stabiliser.
Properties and Applications
Barium/cadmium stabilisers do impart excellent heat stability and outstanding weatherability to PVC compounds. They were used in semi-rigid and flexible foil for products such as roofing membranes and in rigid applications for outdoor use such as window profiles. In Europe , they have been replaced by barium/zinc stabilizers in foils.
Safety, Health and Environmental Issues
Although cadmium is widely distributed in nature and is present in low concentrations in soil, water and air, there have been major concerns about the effect that higher concentrations of cadmium dust have on human health and on the environment. No stabiliser containing cadmium has ever been used for food contact applications or toys. The EU Directive 91/338 still allowed the use of cadmium stabilisers in window profile and roofing membranes but the Voluntary Agreement of the PVC Industry signed in 2000 resulted in discontinuation of use of cadmium stabilizers by all its members as from 2001. Directive 91/338 was included in Annex XVII of the REACH chemical Regulation (Restrictions) when REACH entered into force. The provisions regarding cadmium were amended in 2011 by Regulation 494/2011, which extended the 0.01 % cadmium limit to all PVC articles, but contains a derogation for most rigid PVC construction products containing recovered PVC, where cadmium levels may be up to 0.1 % weight. This derogation will be reviewed no by end 2017.