Man does not come into the world pre-determined. The lifetime set of environmental conditions impinging on a given individual has been termed the ambiome, which together with the genome and the proteome determines each individual's development and construction. Among the most important elements making up the ambiome are endocrine disruptors. An endocrine disruptor is a chemical substance that has adverse effects on an organism or its progeny, through the endocrine system. The number of known endocrine disruptors is large and continuously increasing, and includes both naturally occurring and synthetic substances. We are convinced that they entail genuine problems; although it is difficult to assess their magnitude and real significance, and we will certainly need some time, probably several decades, to obtain conclusive results; but even so, we consider that the existing body of evidence about effects of endocrine disruptors on human health is sufficiently worrying to justify precautionary measures.