Endpoints for responses of fish to chronic toxic exposures

Suter, Glenn; Rosen, Aaron E.; Linder, Ernst; Parkhurst, David F.

doi:10.1002/etc.5620061009

Cited by 98 publications

(36 citation statements)

References 74 publications

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“…However, these types of full and multigenerational life‐cycle tests are extremely resource intensive. This resulted in the use of progressively more abbreviated assays, focused mostly on early survival and development, for regulatory purposes and risk assessment [3–5]. This tendency, however, has important shortcomings, particularly with respect to the ability to assess contaminant effects on reproduction.…”

Section: Introductionmentioning

confidence: 99%

Description and evaluation of a short‐term reproduction test with the fathead minnow (Pimephales promelas)

Ankley

Jensen

Kahl

et al. 2001

Enviro Toxic and Chemistry

280

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Due to the time and expense associated with full life-cycle testing, most current toxicity tests with fish do not explicitly consider reproductive output as an endpoint but, rather, focus on early life-stage survival and development. However, some classes of chemicals could adversely impact reproduction at concentrations below those that affect development. Further, estimates of the effects of toxic compounds on reproductive output can be critical to the ecological risk assessment process. In this manuscript, we describe a short-term reproduction test with the fathead minnow (Pimephales promelas) and evaluate the test using two model reproductive toxicants, methoxychlor (an estrogenic compound) and methyltestosterone (an androgenic chemical). The test is initiated with reproductively mature animals and is comprised of a pre-exposure phase of 14 to 21 d, followed by a chemical exposure of up to 21 d. During and at completion of the test, several endpoints related to reproductive fitness and endocrine function are assessed. Both chemicals evaluated in our study caused a significant decrease in fecundity of the fish at nominal concentrations of 5.0 micrograms/L (methoxychlor) and 0.2 mg/L (methyltestosterone). Methoxychlor decreased plasma concentrations of one or more steroids (testosterone, 11-ketotestosterone, beta-estradiol) in both sexes and caused a significant induction of plasma vitellogenin in males, a response consistent with activation of the estrogen receptor by the pesticide (or its metabolites). Methyltestosterone decreased plasma concentrations of sex steroids and adversely affected gonadal status (as evaluated by relative weight and histopathology) in both sexes. The androgenic nature of methyltestosterone was clearly expressed as masculinization of exposed females via formation of nuptial tubercles, structures normally present only in reproductively active males. The chemical also caused a significant induction of plasma vitellogenin in both males and females; this unexpected estrogenic response was most likely due to aromatization of the androgen to a form capable of binding to the estrogen receptor. These studies demonstrate the utility of this short-term assay for identifying chemicals that exert reproductive toxicity through alterations in endocrine systems controlled by estrogens and androgens.

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Section: Introductionmentioning

confidence: 99%

Description and evaluation of a short‐term reproduction test with the fathead minnow (Pimephales promelas)

Ankley

Jensen

Kahl

et al. 2001

Enviro Toxic and Chemistry

280

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“…Finally, when the experimental dataset obtained from standard toxicity bioassays collects information on both the dose and time responses, as recommended by Suter II et al (1987), it is feasible to predict any response for any concentration and time of exposure. Ecological risk assessment methods would benefit immensely from this new modelling approach, as it allows rapid estimation of such responses, a step required in recent frameworks for risk of wildlife populations (Nacci et al 2005).…”

Section: Discussionmentioning

confidence: 99%

Simplified models to analyse time- and dose-dependent responses of populations to toxicants

Sánchez‐Bayo

Goka

2007

Ecotoxicology

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The basis of ecotoxicology lies currently in the dose-response of organisms to toxicants, as typically described by probit and logistic models. While recognising its merits, standard endpoints ignore the process of toxicity with time, and consequently our ability to predict direct toxic effects in environmental risk assessments is seriously curtailed. Although the response of toxicants with time has been studied before, its application in ecotoxicology remains underutilised. One reason is that no convincing mechanism has been proposed to explain the hyperbolic curves of such responses, whereas a variety of models have been used to describe them. The explanation of both time- and dose-dependent responses is found ultimately in the natural variability of receptor sites among individuals of populations exposed to a toxicant inhibitor with time. The process can be explained by the kinetics of inhibition, and is appropriately described by a simple mathematical expression like the Michaelis-Menten equation, though other asymptotic models (e.g. logistic model) can also be used. The advantage of the hyperbolic model is that median effect values (e.g. LC(50) for dose- and ET(50) for time-dependent responses) enable calculation of toxicity effects at any concentration level and/or time of exposure, thus making it especially attractive for risk assessment.

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“…The results of the mesocosm experiment indicate that more controlled field studies may be needed to determine if there are water quality parameters that could influence fish growth in sites containing tailings wastewater. While growth bioassays using larval fish are a quick, useful starting point in determining chronic toxicity of effluent, the results of these tests must be applied with caution to field situations, to other phases of an organism's life cycle, and to different species [39,40]. Although the chemical constituents of SCL‐processed wastewater may not impede growth or survival of fish directly, characteristics of the water may affect the development of viable self‐perpetuating fish populations in sites containing MFT and/or TPW through complex, indirect mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Growth of fathead minnows in oilsand‐processed wastewater in laboratory and field

Siwik

Meer

MacKinnon

et al. 2000

Enviro Toxic and Chemistry

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Two waste products of Syncrude Canada Ltd. (SCL) oilsands mine are mature fine tailings (MFT), a toxic aqueous suspension of particles, organic acids, bitumen, and metals, and tailings pond water (TPW), a saline solution containing organic and inorganic contaminants. The chemical profiles of MFT interstitial water and TPW are very similar. Syncrude Canada has proposed disposing of MFT in constructed lakes, which would be lined with MFT and capped with clean water. As the MFT consolidates, MFT‐associated water would be released into the overlying watercap. Prototype ponds support fathead minnows (Pimephales promelas), but the long‐term viability of these populations is unknown. This study attempts to determine if exposure to MFT and TPW, a related waste product, affected growth of fathead minnow larvae in the laboratory and field. Laboratory larval growth bioassays (7 and 56 d) on whole effluent from numerous prototype ponds yielded no significant differences in dry weight, but one 7‐d bioassay showed reduced survival in two SCL sites. A 56‐d growth bioassay showed significant increases in length of fish exposed to SCL wastewater at 7 d but not at 28 or 56 d. Larvae exposed as embryos and then introduced into field mesocosms did display significant differences in dry weight. In this instance, fish exposed to wastewater were significantly larger during the laboratory portion of the test (initial), but after 21 d in a field mesocosm (final), they were similar in size or smaller than fish growing in nonprocessed water.

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Endpoints for responses of fish to chronic toxic exposures

Cited by 98 publications

References 74 publications

Description and evaluation of a short‐term reproduction test with the fathead minnow (Pimephales promelas)

Description and evaluation of a short‐term reproduction test with the fathead minnow (Pimephales promelas)

Simplified models to analyse time- and dose-dependent responses of populations to toxicants

Growth of fathead minnows in oilsand‐processed wastewater in laboratory and field

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