Estimating the Effects of 17-Ethinylestradiol on Populations of the Fathead Minnow Pimephales promelas: Are Conventional Toxi
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- 作者：Eric P. M. Grist ; N. Claire Wells ; Paul Whitehouse ; Geoff Brighty ; and Mark Crane
- 刊名：Environmental Science & Technology
- 出版年：2003
- 出版时间：April 15, 2003
- 年：2003
- 卷：37
- 期：8
- 页码：1609 - 1616
- 全文大小：142K
- 年卷期：v.37,no.8(April 15, 2003)
- ISSN：1520-5851
文摘
Environmental benchmarks have recently been proposedfor several steroids including the synthetic steroid, 17
-ethinylestradiol (EE2). These benchmarks are based onextrapolation from studies involving long-term exposure ofvarious fish species to EE2. One of the critical studieswas a complete life-cycle experiment performed with thefathead minnow Pimephales promelas over a 289 dayexposure period (2). The lowest observed effect concentration(LOEC) and the no observed effect concentration (NOEC)for gonad histology were 4 and 1 ng L-1, respectively. Thiswas because no testicular tissue could be found in anyfish exposed to 4 ng L-1. In the present paper, the survivaland reproduction data from that study are reanalyzed todetermine the effects of EE2 on the intrinsic rate of populationgrowth (r = ln (
)), a parameter of demographic importance.We estimate critical threshold concentrations withrespect to r and compare these with those previouslyderived from conventional toxicity test summaries. Further,we assess the influence of individual variability onthreshold estimates using a combination of bootstrap andregression approaches, together with a suite of perturbationanalyses. These yield ErC100 values (the concentrationestimated to reduce intrinsic growth rate to zero) of 3.11ng L-1 (linear model) and 3.41 ng L-1 (quadratic model),comparable with a maximum acceptable toxicantconcentration (MATC) of 2 ng L-1 for feminization ofexposed fish calculated by Laenge et al. (2). Our resultsindicate that reduction in population growth rate withincreasing concentration occurred more through EE2 actingto reduce fertility than survival rates. The significance ofthese summary statistics when deriving environmentalbenchmarks for steroid estrogens is discussed in the contextof affording protection to populations following long-termexposure.
-ethinylestradiol (EE2). These benchmarks are based onextrapolation from studies involving long-term exposure ofvarious fish species to EE2. One of the critical studieswas a complete life-cycle experiment performed with thefathead minnow Pimephales promelas over a 289 dayexposure period (2). The lowest observed effect concentration(LOEC) and the no observed effect concentration (NOEC)for gonad histology were 4 and 1 ng L-1, respectively. Thiswas because no testicular tissue could be found in anyfish exposed to 4 ng L-1. In the present paper, the survivaland reproduction data from that study are reanalyzed todetermine the effects of EE2 on the intrinsic rate of populationgrowth (r = ln ()), a parameter of demographic importance.We estimate critical threshold concentrations withrespect to r and compare these with those previouslyderived from conventional toxicity test summaries. Further,we assess the influence of individual variability onthreshold estimates using a combination of bootstrap andregression approaches, together with a suite of perturbationanalyses. These yield ErC100 values (the concentrationestimated to reduce intrinsic growth rate to zero) of 3.11ng L-1 (linear model) and 3.41 ng L-1 (quadratic model),comparable with a maximum acceptable toxicantconcentration (MATC) of 2 ng L-1 for feminization ofexposed fish calculated by Laenge et al. (2). Our resultsindicate that reduction in population growth rate withincreasing concentration occurred more through EE2 actingto reduce fertility than survival rates. The significance ofthese summary statistics when deriving environmentalbenchmarks for steroid estrogens is discussed in the contextof affording protection to populations following long-termexposure.