Priority setting strategies for regulatory testing of industrial chemicals

For the majority of the estimated 70,000 industrial chemical substances available on the European market today there is not enough information to enable a reasonably complete assessment of the risks that they might pose to man and the environment. Any strategy for the generation of additional data for these substances should aim at making testing as efficient as possible taking into account environmental and health protection, time, monetary cost and animal welfare. To achieve this, appropriate priority setting rules are needed. The main criterion currently used for regulatory priority setting for testing of industrial chemicals is production volume; the higher the production volume, the more information is required. This was also the main criterion in the former legislation, preceding REACH (Registration, Evaluation and Authorisation of Chemicals). The aim of this thesis is to evaluate other priority setting criteria and their implications for risk management, in particular classification and labelling. The first paper in this thesis includes a study of the efficiency ratio for some of the tests required for the notification of new substances, i.e. the ratio between the likelihood that the test will lead to a classification, and the monetary cost of performing the test. The efficiency ratio was determined for the standard tests for acute oral toxicity, irritation, sensitisation and subacute toxicity using data from 1409 new chemicals notified in Europe between 1994 and 2004. The results of this investigation suggest that, given limited resources for testing, it is more efficient to perform acute toxicity tests on a larger number of substances rather than to perform additional subacute toxicity studies on the substances already tested for acute toxicity. The second paper included in this thesis, reports the results from a comparative study of the bioaccumulating properties of substances being (a) classified as carcinogenic, mutagenic and/or toxic to reproduction (CMR-substances), or (b) classified as acutely toxic or (c) unclassified. The purpose of this investigation was to evaluate potential consequences of prioritising bioaccumulating chemicals for evaluation and testing, as this is one of the strategies prescribed in REACH. The results of this study suggest that bioaccumulating substances are neither overnor underrepresented among the CMR-substances. This result lends support to the use of the bioconcentration factor for priority setting. The studies reported in this thesis utilize existing data on classification of substances as an indicator of the outcome of the risk assessment process, relating priority setting methods to the risk management measures that they give rise to. To the best of my knowledge there are still only very few studies published that address the issue of priority setting in chemicals control using this approach, and in my view there is need for more studies of priority setting methods and a further development of priority setting strategies that are science-based.