The drive to ban the NOEC/LOEC in favor of ECx is misguided and misinformed

Green, John W.; Springer, Timothy A.; Staveley, Jane P.

doi:10.1002/ieam.1367

Cited by 38 publications

(39 citation statements)

References 12 publications

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“…There are currently no useful regression models for some responses, including time‐to‐first hatch or swim‐up in avian or fish studies, developmental stage after 28 days (Green et al ), or time‐to‐achieve developmental stage 62 in amphibian metamorphosis studies, or histopathology severity scores in fish studies (Green et al ). For these time‐to‐event data, the measurement is too crude or the length of the studies too short for standard survival models to be useful.…”

Section: Discussionmentioning

confidence: 99%

Issues with using only regression models for ecotoxicity studies

Green¹

2015

Integr Envir Assess & Manag

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Section: Discussionmentioning

confidence: 99%

Issues with using only regression models for ecotoxicity studies

Green¹

2015

Integr Envir Assess & Manag

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“…Recent articles highlight division in the scientific community regarding retention and replacement of the NOEC [15][16][17][18][19]. Concerns raised about continuing use of the NOEC include the influence of experimental design (e.g., choice of concentrations, spacing of concentrations across the range) and technical issues (e.g., high control mortality) on the accuracy of NOEC calculations [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Evaluation and comparison of the relationship between NOEC and EC10 or EC20 values in chronic Daphnia toxicity testing

Beasley

Belanger

Brill

et al. 2015

Enviro Toxic and Chemistry

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Hypothesis-based no-effect-concentration (NOEC) and regression-based x% effect concentration (ECx) values are common statistical approaches used to summarize ecotoxicological effects. Controversy over the NOEC model has prompted a movement toward discontinuation of the NOEC in favor of ECx, but the best x% effect surrogate for NOEC has not yet been determined. Historically, 10% and 20% effect concentrations (EC10 and EC20) have been treated as NOEC analogs. Given these measurements' importance to ecotoxicology, further understanding of the relationships between NOEC and EC10 or EC20 is crucial. In the present study, a metadataset of daphnid chronic toxicity tests was compiled to analyze the strength and significance of NOEC:EC10 and NOEC:EC20 relationships. The impact of endpoint (e.g., mortality, reproduction) and test condition parameters (e.g., pH, temperature) on NOEC:EC10 and NOEC:EC20 was evaluated. Mortality endpoints were most sensitive 51% of the time, with growth and reproductive endpoints constituting the remainder, underscoring the value of using multiple endpoints to evaluate toxic effects rather than relying on reproduction as the a priori most sensitive endpoint. When test condition parameters were less restricted (e.g., pH, hardness), the NOEC:EC20 association was more robust, suggesting that variability introduced by test implementation increased variability in ECx calculation. The analysis revealed that, overall, EC10 was a more suitable analog than EC20 for NOEC. Recommendations include refinement and reporting of the test parameters pH and hardness to minimize variability in ECx calculation.

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“…As we have pointed out in such cases, the only meaningful descriptor of the concentrationresponse relationship is the mean response taken over all measured concentrations [3]. Green and his collaborators' repeated claims that, in effect, the NOEC can somehow overcome the aforementioned problems resulting from either a poorly designed concentration-response experiment or an observation on the reality of a nonexistent response are not convincing [1,2,4].…”

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Don't be fooled—A no‐observed‐effect concentration is no substitute for a poor concentration–response experiment

Fox

Landis

2016

Enviro Toxic and Chemistry

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Renowned mathematician and science historian Jacob Bronowski once defined science as "the acceptance of what works and the rejection of what does not" and noted "that needs more courage than we might think." Such would also seem to be the case with noobserved-effect concentrations (NOECs) and no-observed-effect levels in ecotoxicology. Compelling arguments were advanced more than a quarter of a century ago as to why the use of a model to describe the concentration-response relationship was preferable to an isolated metric, with the NOEC singled out as a particularly poor toxicity measure. In the ensuing years numerous articles critical of the NOEC have been written, with some calling for an outright ban on its use. More recently, arguments have been made for the retention of NOECs, with supporters suggesting that this metric is particularly useful in situations where the concentration-response relationship is weak or nonexistent. In addition, it has been claimed that there are situations in ecotoxicology where suitable models are simply not available. These arguments are not correct, and they also have impeded the decades-overdue incorporation of numerous recommendations based on research that NOECs should no longer be used. In the present study the authors counter some of the most recent claims in support of NOECs and provide new insights for 1 class of problem claimed not to be amenable to such modeling. They are confident that similar insights will be developed as further original research in this area is undertaken. THE NO-OBSERVED-EFFECT CONCENTRATION FALLACYIn his recent learned discourse [1], Green continues to assert that the no-observed-effect concentration (NOEC) is a legitimate toxicity metric worthy of continued use by ecotoxicologists, particularly when dealing with "problematic" data such as those for which either "the concentration-response . . . shape is very shallow," "the control response is highly variable," or the "response has no pattern at all except at the highest 1 or 2 concentrations" [2]. Green suggests that in such cases "there might be no basis for proposing a model" [2], arguing instead that analysis of variance (ANOVA) techniques be used to generate the now widely discredited NOEC. As we have pointed out in such cases, the only meaningful descriptor of the concentrationresponse relationship is the mean response taken over all measured concentrations [3]. Green and his collaborators' repeated claims that, in effect, the NOEC can somehow overcome the aforementioned problems resulting from either a poorly designed concentration-response experiment or an observation on the reality of a nonexistent response are not convincing [1,2,4].The most recent contribution by Green perpetuates this assertion by stating "the NOEC often provides good information when no sound regression model exists" [1]. There is a logical inconsistency with this claim: if there is no response as a function of varying concentration, then there is no point at which the response changes and hence no concent...

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The drive to ban the NOEC/LOEC in favor of ECx is misguided and misinformed

Cited by 38 publications

References 12 publications

Issues with using only regression models for ecotoxicity studies

Issues with using only regression models for ecotoxicity studies

Evaluation and comparison of the relationship between NOEC and EC10 or EC20 values in chronic Daphnia toxicity testing

Don't be fooled—A no‐observed‐effect concentration is no substitute for a poor concentration–response experiment

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