Assault upon the hormone system

The study collates indications and evidence of chemicals-related reproductive damage for seven animal species in aquatic and marine habitats in Europe (North Sea and Baltic Sea) and the polar region. The species examined include: Common European Starfish and Common Whelk as echinoderm or mollusk representatives; two fish species (Herring, Rainbow Trout); one bird species (Common Tern) and Harbor Seal (and other seals) and Polar Bear as mammal representatives. The study is based upon a comprehensive desk study of the literature and questioning of experts. For all species, findings in non-European habitats were also taken into consideration. In six of the seven species examined, endocrine-disrupting effects of various environmentally relevant chemicals are proven; in Polar Bears such effects are suspected. In five of these cases, disturbances of the hormonal balance caused by environmental chemicals disrupting the endocrine system play a role in conjunction with hormone-like effects of contaminants. Where identified, the contaminants are mainly PCBs, DDT and other pesticides, and various heavy metals. Chlorinated organic compounds play a significant - but not the only - role. Non-chlorinated compounds include, besides the heavy metal compounds (such as cadmium, TBT), alkylphenols or, in experimental studies, phthalates (PVC softeners) and other synthetic substances used in consumer applications. The public debate on the endocrine-disrupting effects of environmental chemicals and hormones has until now been dominated by spectacular images of damage reported from field observations. The effects of TBT in the Common Whelk (and effects reported for many other snail species, too), ranging up to sterility and local-regional extirpation, make it plain that endocrine disrupting chemicals can produce such severe effects. In addition, however, the observations now available suggest much more broadly-based, insidious and possibly synergistic effects of environmental chemicals and hormones which, in interplay with other factors (such as habitat degradation, overfishing) impair the reproductivity of many species (clearly so in, for instance, Harbor Seals). These effects do not express themselves as immediately apparent population collapses, but contribute to the erosion of species abundance