Terminology of Gonadal Anomalies in Fish and Amphibians Resulting from Chemical Exposures

During the past decade, the scientific community and the public have become increasingly aware that some chemicals have the potential to interfere with endocrine systems in both vertebrate and invertebrate wildlife species (WHO 2002; Ankley et al. 1998). One aspect of these effects has been the observation of gonadal abnormalities in fish, amphibians, reptiles, birds, and mammals, including humans (Kavlock et al. 1996). To date, most research in this field has focused on demasculinization or feminization effects on male animals (Sumpter et al. 1996; Gimeno et al. 1998a,b; Crain et al. 1999; Jobling et al. 1998; Kloas et al. 1999; Hayes et al. 2002). Evidence for this estrogenic or antiandrogenic type of “endocrine disruption” has come largely from studies of teleost fish, either in controlled laboratory experiments where they have been exposed to specific chemicals or in the wild where organisms have been exposed to mixtures of compounds (Jobling et al. 1998; Harries et al. 1999; Minier et al. 2000; Hecker et al. 2002; Matthiessen et al. 2002). More recently, attention has shifted toward other groups of animals living in or closely associated with aquatic environments, such as alligators (Crain et al. 1999) and amphibians (Kloas et al. 1999; Hayes et al. 2002; Hecker et al. 2004).