[Methods of toxicologic evaluation--possibilities and limits].

Toxicological knowledge is founded on observation in humans consisting of casuistic presentations and epidemiologic research and on animal experiments. The possibilities and limitations of these sources of knowledge are presented with special reference to the problems of the dose and of toxic interactions. The limitations of toxicological knowledge primarily result from the impossibility to prove "no action". Therefore, it is not possible to prove the absolute safety of a substance but only the acceptability by assessing its advantages and risks.