There is no uniform approach in the European Union for the risk assessment of occupational exposure to non-threshold carcinogens. A major cause of these differences is choices on cancer risk levels used for the assessment. This has emerged from a report by RIVM.

Workers can be exposed to chemical agents at their workplace. In order to assure that this exposure will not result in adverse effects on health, occupational exposure limits (OELs) are established.  On the other hand, OELs for non-threshold carcinogens are derived using a ‘cancer risk level’: the number of additional cases of cancer due to exposure to a carcinogenic.

European worker legislation prescribes that carcinogenic substances should be substituted wherever possible. If this is not possible, employers must ensure that exposure is as low as is reasonably
achievable. Currently, the approach on how to deal with carcinogens differs amongst Member States.


Differences observed in the risk assessment of non-threshold carcinogens are largely due to choices concerning cancer risk levels used. Other sources for differences are the choice of the exposure level in animal experiments, that causes the adverse effect and of the uncertainty factors applied in the extrapolation from animals to humans.


Apart from these differences, there are many similarities between Member States. One of the similarities is that the methodologies are based on similar principles. All apply similar general criteria for quality and adequacy of the data selected to derive the limits. Also, all Member States prefer the use of human data above the use of animal data, but recognize that in most cases these will not be available or will not form a sufficient basis on their own.


In addition to comparing methodologies for the derivation of exposure limits, RIVM evaluated databases and other sources containing information on occupational exposure to carcinogens. Based on these results, the most common carcinogenic substances will be identified and a priority substances list will be developed for the derivation of occupational exposure levels within the European Union.