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What Makes a Concentration Environmentally Relevant? Critique and a Proposal Lennart Weltje*,† and John P. Sumpter‡ †
BASF SE, Crop Protection − Ecotoxicology, Speyerer Strasse 2, 67117 Limburgerhof, Germany Brunel University London, Kingston Lane, Uxbridge, Middlesex, UB8 3PH, U.K. dose (and variants thereof), in the titles of publications in Web of Knowledge (Figure 1). It is clear that use of the term “environmentally relevant” has increased dramatically in the last 20 years (ca. 10-fold). The authors of the majority of these papers are claiming that certain adverse effects occur at concentration levels (commonly) occurring in the environment, and that therefore a risk is inferred. In fact, our analysis significantly underestimates the use of the term “environmentally relevant”, because we searched only in the titles of papers, whereas it may not be in the title, but instead elsewhere in the paper. If the search assesses the prevalence of the same phrase in the title, abstract, or keywords, then it yields 4494 hits, as compared to 409 hits for use of the phrase in the title alone. Of those hits, 314 and 23, respectively, were in papers published in Environmental Science & Technology. In both cases the frequency of use of the phrase has increased markedly in the last 20 years, as shown in Figure 1, and is still doing so. As an example, authors of a recent paper1 claimed that their results were obtained at “environmentally relevant concentrations” in the abstract but not the title. As it happens, even the lowest concentration of their test chemical (17α-ethinylestradiol) was not environmentally relevant. INTRODUCTION
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The primary reason for conducting ecotoxicology research is to obtain information that can be used by regulators to protect the environment from the many chemicals accidentally or intentionally released into the environment. Hence, to be maximally useful to regulators, ecotoxicology research should address environmentally relevant concentrations of chemicals. Recent advances in analytical chemistry, such as the development of tandem mass spectrometry, have enabled accurate measurements of the concentrations of most chemicals present in the environment. Advances in modeling have also improved our knowledge of the likely concentrations of chemicals in the environment. Thus, we now have a good idea of what the environmentally relevant concentrations of most chemicals are. Researchers interested in whether or not chemicals harm wildlife should be able to conduct their research using concentrations of test chemicals that are representative of those experienced by wildlife. Judging by the frequency that the words “environmentally relevant” seem to be appearing in the titles of ecotoxicology publications, it might be assumed that this was indeed occurring; that we are moving from research that determined lethal concentrations of chemicals to research that was much more realistic. But is that opinion correct? To shed light on whether or not ecotoxicology research is progressively becoming more environmentally relevant, we assessed the use of the words “environmentally relevant”, combined with exposure or level or concentration or © XXXX American Chemical Society
Figure 1. Number of papers with “environmental* relevant” or “field relevant” and expos* or level* or concentration* or dose* in the title against publication year (Web of Knowledge search conducted July 17, 2017).
A closer inspection of the literature reveals that the term “environmentally relevant” is often loosely used. For example, reference is often made to the highest measured concentrations that are reported in papers describing measurement campaigns, whereas most lower values, or concentrations below detection Received: September 10, 2017
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DOI: 10.1021/acs.est.7b04673 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
Viewpoint
Environmental Science & Technology limits, are ignored.2 Further, concentrations reported to justify the statement “environmentally relevant” may be wastewater influent or effluent concentrations, not river concentrations, yet aquatic organisms live in rivers, not in undiluted effluent of wastewater treatment works. It is apparent from the literature that the environmental relevance of chemical concentrations needs to be justified much better than it is presently. Therefore, this opinion piece aims to contribute to the debate by making proposals on how to deal with environmental measurements and from these define environmentally relevant values.
randomly from the literature, but instead provide a representative range of concentrations. This alternative approach might be the only option if very few measured concentrations of a particular chemical have been reported. An aside, It may not have escaped some readers of this article that its authors have, by publishing the article, added yet another article with the words “environmentally relevant” in the title to the literature!
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected].
WHAT IS CAUSING THE INCREASE? We encourage and support authors who attempt to place their results in context and to establish the relevance of the obtained effect values (e.g., LOEC or EC50) for the field situation and/or for the environmental risk assessment of a chemical. Often, the question of relevance is posed by editors, reviewers, and supervisors. Also, scientists are under considerable publication pressure, which could be a reason for claiming effects at environmentally relevant concentrations, in the hope that their manuscript is more likely to be accepted for publication and in turn that the paper is more likely to be cited, which would benefit both the scientists and the journal (because it would increase the journal’s impact factor). Apparently, it is much less common to state that toxicity occurs only above concentrations typically found in the environment, or that results demonstrate that the environmental risk assessment, including possible mitigation measures, is actually sufficiently conservative. Although the increase in the number of papers using the term “environmentally relevant” is partly due to the publication of progressively more papers in ecotoxicology over the time period examined, the ca. 10-fold increase in the use of the term (see Figure 1) is much higher than the increase in the number of published ecotoxicology papers in the last 20 years.
ORCID
Lennart Weltje: 0000-0002-5191-4158 Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Young, B. J.; Lopez, G. C.; Cristos, D. S.; Crespo, D. C.; Somoza, G. M.; Carriquiriborde, P. Intersex and liver alterations induced by long-term sublethal exposure to 17α-ethinylestradiol in adult male Cnesterodon decemmaculatus (Pisces: Poecilidae). Environ. Toxicol. Chem. 2017, 36 (7), 1738−1745. (2) Weltje, L. No proof of synergy at environmentally realistic concentrations of prochloraz and esfenvalerate − A reaction on “Synergy in microcosms with environmentally realistic concentrations of prochloraz and esfenvalerate” by Bjergager et al. (Aquat. Toxicol. 101 (2011), 412 − 422). Aquat. Toxicol. 2013, 140−141, 466−468. (3) Hornung, R. W.; Reed, L. D. Estimation of average concentration in the presence of nondetectable values. Appl. Occup. Environ. Hyg. 1990, 5 (1), 46−51. (4) Shumway, R. H.; Azari, R. S.; Kayhanian, M. Statistical approaches to estimating mean water quality concentrations with detection limits. Environ. Sci. Technol. 2002, 36 (15), 3345−3353. (5) FOCUS. FOCUS Surface Water Scenarios in the EU Evaluation Process under 91/414/EEC. Report of the FOCUS Working Group on Surface Water Scenarios, EC Document Reference SANCO/4802/ 2001-rev.2, 2001, 245 pp.
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PROPOSAL Ideally, we would like all authors to collect all concentration measurements made in relevant habitats/environments, including those at or below the limit of detection (LoD). Critically inspect very high concentrations: are they likely to be the result of misuse or an accident, or of a calculation or dilution error? Convert the concentrations equal to or below the LoD to a numerical value, following available methodology.3,4 Then generate a cumulative distribution from which the 90th percentile is calculated5 − this is the highest environmentally relevant concentration. This value can be compared directly to the effect values (e.g., LOEC or EC50) from a toxicity study, or with a regulatory acceptable concentration (RAC), i.e. the toxicity value divided by the relevant assessment factor. If authors are not inclined to adopt this scientific approach to determining the highest likely environmental concentration, we urge them to adopt the alternative approach of stating, clearly, from what environments the concentrations they report come from, instead of providing, as often occurs, only the concentration(s) and the reference from which it came. Thus, for example, authors should state if the concentrations they refer to were present in an influent or effluent of a wastewater treatment works, or a river, and if from a river, was it an effluentdominated stream or alternatively a river receiving little or no wastewater effluent or agricultural runoff. Authors should also not provide just one or two concentrations chosen apparently B
DOI: 10.1021/acs.est.7b04673 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
