Table of Contents
What are plasticisers?
Plasticisers are substances which are added to brittle materials to make them soft, ductile, or extendible, so that they can be worked more easily or acquire particular characteristics of use. They can be found in large quantities in plastics, varnishes, coating agents, sealing compounds, industrial and natural rubber articles, and adhesives. The finishing of textiles also sees the use of flexibilising substances to improve their feel and pliability. Plasticisers can leak out of the different products, thus escaping into the environment and into the food. They can in this way be ingested in significant amounts with food. Direct absorption through the skin is only widely associated with short-chained phthalate esters; absorption in the case of the other phthalate esters is less problematic.
Industry uses many different substances as plasticisers, although, in terms of quantity, low volatile phthalic acid esters currently predominate. Soft resins, oily substances, or natural substances such as camphor, castor oil, or citrates can also however be used. Bis(2-ethylhexyl) phthalate (DEHP) is still used in large quantities as a plasticiser for very many everyday PVC products. PVC containing DEHP is also an ingredient of numerous medical products, for example, infusion tubes and stomach probes. This plasticiser is banned in toys for children.
Due to various negative assessments – amongst others the classification of DEHP by an EU working group as teratogenic and harmful to human fertility – the European plastics industry reduced the proportion of DEHP in its total consumption of plasticisers from 42 to 22 percent between 1999 and 2004. The use of DEHP is continuing to decline. In its place, longer-chain phthalates such as diisononylphthalate and diisodecylphthalate are increasingly being used, which, according to EU criteria, do not need to be labelled and are currently more favourably viewed in respect of their impacts on human health.
Manufacturers frequently combine different types of plasticiser in order to achieve particular material characteristics. To this end, chloroparaffins, phosphoric acid esters, fatty acid esters, hydroxycarbonic acid esters and polyesters are some of the substances used. Some of the substances contained in these plasticisers, in respect of their effects on human health and the environment, give rise for concern. Their volume of use could, however, continue to increase in the future.
In addition to products in which plasticisers are admixed, there are also those in which they are incorporated firmly and permanently into the plastic through copolymerisation. There have been no recorded cases of plasticisers escaping into the environment from these kinds of plastic.
Significant sources of plasticisers in indoor air and house dust are construction materials such as floor coverings, handrails, door and window seals (to the extent to which they contain hard or soft PVC), electrical cables, furniture which is manufactured using adhesives or paints containing phthalates, home furnishings, bath and shower inlays, and shower curtains. Consumers can try as far as possible to avoid plastics which contain flexibilisers, especially soft PVC, and to turn instead to other products, for example those made of polyethylene (PE).
Contamination of the population at large
The German Federal Environment Agency ( Umweltbundesamt ) has for many years been researching the contamination of adults and children with phthalates and other hazardous substances, above all by means of the German Environmental Survey and the Environmental Specimen Bank, human specimen part. The findings of the pilot study of 2001 to the German Environmental Survey 2003/06 (GerES IV) for Children showed that the maximum tolerable daily intake amount of DEHP was, in the case of some children, mainly boys, being exceeded. It has not been possible, however, to establish a correlation between the contents of DEHP in house dust and the internal contamination of children.
The next few years will see the continuation of research projects into the topic of plasticiser contamination, which will be subsidised by the Federal Environment Agency. The results known thus far have been published by the Federal Environment Agency in overview form and in further publications. The Human Biomonitoring Commission has derived and published reference values to describe the background contamination of the population with DEHP.