Kinetic distribution model for chemicals based on results from a standard environmental system.

In order to reduce potential hazards to the environment resulting from production and use of chemicals, some governments have enacted laws and corresponding regulations. Thus, for instance, the German "law on hazardous substances," and the regulation regarding a.o. submission of test data on physiochemical properties of new substances, have been ratified by the Federal Republic of Germany legislation in 1980 and 1981, respectively. This implies that before production, marketing, and use of a new chemical, its potential hazard to human beings and the environment has to be checked. Therefore it is necessary to have available accurate information about the probable fate of this new chemical in the environment, i.e., its distribution among the different environmental compartments. To this end, the submission of basic physiochemical data of a new chemical, such as boiling point, vapor pressure, water solubility, fat solubility, and partition coefficient in the system n-octanol/water, is mandatory for its registration. These data are meant to be used by the official evaluating department as a basis for describing the distribution behavior of the substance in the environment. However, there is no generally accepted procedure yet which would allow the reliable prediction. Such a calculation procedure should comprise all factors decisive for distribution and degradation of chemicals in the environment, according to their significance. We have taken a first step in this direction by carrying out the following experiments, with the aim of developing such a distribution model as well as identifying the physicochemical properties of chemicals required for the prediction of distribution patterns. The distribution patterns of 12 selected substances, having significant differences with respect to their physiochemical properties, were determined via radiotracer technique, in a defined, standardized, terrestrial ecosystem. The results of the experiments were compared with one another as well as with values calculated by use of mathematical models from the literature. These comparisons show that there are certain correlations between the distribution patterns obtained by experiments and those calculated by the stationary distribution models. However, these also indicate that some of the experimental findings cannot be explained within the framework of stationary distribution models. Kinetic models represent a more universal approach toward predicting the distribution of chemicals in an ecological system. Various prototypes are described in the literature but we could not use them due to their mathematical shortcomings.(ABSTRACT TRUNCATED AT 400 WORDS)