Scientific
advances examining
basic mechanisms of endocrine disruption.
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The scope of inquiry related to endocrine disruption has broadened dramatically over the past two decades of research. Originally framed only as "estrogen mimicry" or "estrogens in the environment," research has expanded to include many other hormone systems: estrogen blocking as well as mimickry, androgen blocking, concern for interference with thyroid hormones and progesterone, retinoids... the whole gamut. As research continues to mount about the range of chemical-signalling systems vulnerable to disruption, it is becoming apparent that endocrine disruption is most likely but one example of a broader class of contamination effects, termed "signal disruption." New results are being published frequently in the scientific literature that continue to broaden the scope of inquiry. |
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| No one is exposed to just one chemical. New research examines the nature of interactions among chemicals. Some are additive, some synergistic, some even cancel one another. | ||
| Even for single contaminants working through "traditional" endpoints like estrogen mimickry, the science has become more complex and more challenging to standard approaches to chemical regulation. It turns out that endocrine disrupting chemicals violate a basic assumption of toxicology and modern risk assessment. For classic toxicants, "the dose makes the poison." Higher doses lead to higher effects. For some endocrine disrupting chemicals, however, effects may disappear at higher levels, or become different qualitatively. New research is illuminating the mechanisms by which these not-so-unusual patterns occur. |