| Summary: | During the last few decades, there has been a great concern about the impact of
endocrine disrupting chemicals (EDCs) on the health of wildlife and human
populations. Nonylphenol, a degraded product of a widely used surfactant, has
recently been identified as an estrogenic EDC.
A set of experiments were conducted to examine how exposure to three levels
(4, 20, and lOOppb) of nonylphenol for certain periods (1-3 weeks) affected
physiological function in rainbow trout over time, in terms of their response to an
acute stress of air exposure. It was shown that a high level (lOOppb) of nonylphenol
suppresses the elevation of plasma Cortisol level in rainbow trout in response to the
acute stress of air exposure. In addition, the fish treated with nonylphenol were
incapable of reducing their Cortisol levels back to pre-stress levels after 24 hours. The
normal response of plasma glucose levels to the stress was observed. Plasma levels of
thyroid hormones decreased significantly (p<0.0\) after exposure to the high level of
nonylphenol for 3 weeks. Nitrite, a toxic chemical naturally present in the aquatic
environment, was used in the experiment for comparison and had no effect on the
normal stress response of Cortisol.
The results from these experiments suggest that nonylphenol may have
negative impacts on fish, such as a lower chance of survival and vulnerability to
diseases, by interfering with normal function of the endocrine system. === Science, Faculty of === Resources, Environment and Sustainability (IRES), Institute for === Graduate
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