For three decades now, European environmental policy has been endeavouring to prevent the harmful impact which chemicals can have on natural ecosystems. Not only are all new products subject to very strict criteria, but major efforts have also been channelled into a multidisciplinary research project, in order to evaluate the potential effects of the 100,000 or so existing chemical formulations.
1979: the European Directive on Dangerous Substances - discussed since 1967 and amended for the seventh time - is transposed into national legislation. Any chemical substance classed as "new" must in future undergo tests to determine any risks which it may pose to the environment. It may only be freely sold on the European market if these risks are found to be minimal.
There still remained the problem, however, of all the substances already in use prior to that date. It was decided to compile an inventory of these substances - the EINECS (European Inventory of Existing Commercial Chemical Substances). Published in 1990, the latter listed over 100,000 chemicals.
The need for a multidisciplinary approach
"Identifying the environmental risks posed by this huge number of substances is a very complicated process. The necessary data about their emissions and possible impact on the environment are non-existent in most cases," observes Doctor Karcher, of the Ispra Joint Research Centre. "An in-depth evaluation of these risks calls for multidisciplinary expertise involving biologists and toxicologists (capable of studying the effects of the substances on living organisms), chemists (analysing the structure of the chemicals) and statisticians, capable of processing the experimental data which we have available."
It was in an effort to bring all these experts together that a large European research project was launched in 1992, mainly under the leadership of the University of Utrecht (Netherlands) and the European Chemicals Bureau of the European Commission. Eight research groups - including Slovak and Czech teams - were assigned to the project.
The advantages of the QSAR method
The participants set themselves a specific objective: to validate a method of evaluating the environmental impact of chemical substances by determining the quantitative links between their physico-chemical structure and their chemical and biological activity. This approach is known as the QSAR method (Quantitative Structure-Activity Relationships). Where this relationship can be established, the evaluation can be extended by predicting the activity of substances which have a similar chemical structure. It then becomes possible to deduce the activities of a large number of molecules, by grading them according to structure and properties, without having to test them all.
An initial assessment was made after two and half years' research, in June 1995. The QSAR method has proven particularly useful for modelling the toxicity of products in an aquatic environment, or through soil absorption. It has enabled scientists to evaluate the consequences of massive discharges of certain chemical substances by agriculture or industry. The researchers looked in particular at the effect of pesticides on aquatic ecosystems, and the way soil and sediments absorb them. They also greatly extended the range of criteria used to describe the relationships between the chemical structure and the activity of the substance in question.
The QSAR method would need to be improved, however, in order to be applied to the numerous substances found on the EINECS list. In those areas where it fails to measure up, tests are the only alternative.
The economic spinoffs of such research are considerable. "Thanks to the QSAR method, the national environmental agencies and chemical industries can reduce the number of substances to be studied, and so concentrate more resources on analysing those chemicals affected by the European Union's regulations on existing substances which have far more important implications for the environment," believes Dr. Karcher.
Thanks to the project's findings, the European Chemicals Bureau is now busy validating and implementing the QSAR method in order to supplement the data contained in the EINECS list. Preparations are also under way for an additional project aimed at studying the problems posed by "endocrine disruptor" substances, liable to interfere with human reproductive functions. The Bureau has also launched a project designed to validate the method, in collaboration with the United States and Japan.