Endocrine disrupters of the stress axis in natural populations: How can wetell?

Often, as environmental endocrinologists, we observe animals in nature with the goal of describing their normal endocrinology, However, the contaminat ion of virtually all natural habitats by chemicals of anthropogenic origins (e.g., PCBs, organochlorines, phytoestrogens, alkyphenols, heavy metals) t hat might alter endocrine conditions suggests we need to reevaluate many of our field studies with respect to points of reference or controls. The imp aired response of the stress axis of feral brown trout, Salmo trutta, corre lated with chronic exposure to heavy metals is examined as a case in point although the problems extend to other hypothalamic axes as well. Our studie s emphasize that measurement of one static endocrine parameter to assess th e health of any hypothalamus-pituitary axis (e.g., plasma cortisol levels t o indicate stress) should not be used as a biomarker for field studies.