CONFUSION OF CONCEPTS IN MIXTURE TOXICOLOGY

Regulatory limit values are generally set for single compounds. Howeve r, humans are exposed both simultaneously and sequentially to a wide v ariety of compounds. Some concepts on mixture toxicology are discussed in this introduction to the European Conference on Combination Toxico logy. Studies on mixtures are often accompanied by statements about th e type of combined action, which can be, for example, additive, synerg istic or antagonistic. Unfortunately, comparison of results is hardly possible for various reasons. First, the terminology for indicating co mbined action is far from consistent. Bearing this in mind, researcher s should be explicit in the definitions of terms. Secondly, depending on the model, different conclusions may be drawn from the same results . It is therefore important to provide clear definitions of the null h ypothesis. Thirdly, adequate statistical methods should be used for te sting the null hypothesis. In the past, many mixtures studies either u sed no statistics or used statistics incorrectly. Last, but not least, the study should be designed in such a way that it should be possible to obtain clear answers. In this introduction, it is stressed that en vironmental toxicologists should focus on the low-dose region of the d ose-effect curies. It appears that interactions are less plausible at low doses. Dose additivity,however, cannot be excluded. Copyright (C) 1997 Elsevier Science Ltd.