RIVM Report 2016-0184
Polycyclic aromatic hydrocarbons (PAHs) are harmful substances that can be present in, among other things, rubber articles. For the safe use of rubber articles, like shock-absorbing tiles, producers have to comply with the European limit which has been set for PAHs in consumer products. Shock-absorbing rubber tiles are made of used car tyres and contain PAHs.
RIVM has received a request to investigate whether the current product limit for PAHs in rubber tiles provides an adequate level of protection against the development of cancer. At this moment, only an indication of the extra risk of developing cancer can be given, because there is a lack of reliable data regarding the exposure of children to PAHs from the tiles (via dermal contact and hand-to-mouth contact). These data, however, are necessary for a proper risk assessment to be made. Missing data, for example, include the skin-tile contact time and the rate that the PAHs migrate from the tiles. Further investigation into these data was not possible within the time limits of the study. To reduce the uncertainties in the present risk assessment, additional data on the exposure are required.
In addition, to derive the extra risk of adverse health effects from the results of animal studies, so-called safety factors are used. In this study, a standard safety factor for substances which cause cancer was used. At this moment, there is no agreement within Europe on the use of extra safety factors for cancer-causing substances. For this reason, RIVM recommends initiating a discussion at European level to obtain agreement on this subject.
In general, the risks of the exposure to substances which cause cancer is indicated as the extra number of people who get cancer per million of exposed people; the term ’extra’ is used as people have the risk of developing cancer without this exposure. An extra risk of 1 in a million exposed people is regarded as negligible in the risk assessment of substances causing cancer. In this study, because of the quantified uncertainties, the extra cancer risk is presented as a range, meaning that the extra risk lies between two extreme values. If the PAH-concentration in the rubber tiles is equal to the limit for consumer products, this range lies around the negligible risk level of 1 per million. At the maximum value of the range the negligible risk level is slightly exceeded.
The results of this study can be used in the evaluation of the product limit for PAHs in consumer articles by the European Commission. In this evaluation it is important to also include the exposure to PAHs from other consumer articles.