An improved method for calculating toxicity‐based pollutant loads: Part 1. Method development

Pollutant loads are a means for assessing regulatory compliance and setting targets to reduce pollution entering receiving waterbodies. However, a pollutant load is often comprised of multiple chemicals, which may exert joint toxicity on biota. When the ultimate goal for assessing pollutant loads is to protect ecosystems from adverse effects of toxicants, then the total pollutant load needs to be calculated based on the principles of mixture toxicology. In this article, an improved method is proposed to convert a pollutant load to a toxicity-based load (toxic load) using a modified toxic equivalency factor (TEF) derivation method. The method uses the relative potencies (RePs) of multiple species to represent the response of the ecological community. The TEF is calculated from a percentile of a cumulative distribution function (CDF) fitted to the RePs. The improvements permit the determination of which percentile of the CDF generates the most environmentally relevant and robust toxic loads. That is, environmental relevance ensures that a reduction in the toxic load is likely to result in a corresponding improvement in ecosystem health and robustness ensures that the calculation of the toxic loads is not biased by the reference chemical used. The improved methodology will therefore ensure that correct management decisions will be made and ultimately, a reduction in the toxic load will lead to a commensurate improvement in water quality. Integr Environ Assess Manag 2017;13:746-753. © 2016 SETAC.

[1]  J. Westendorf,et al.  Comparison of an array of in vitro assays for the assessment of the estrogenic potential of natural and synthetic estrogens, phytoestrogens and xenoestrogens. , 2001, Toxicology.

[2]  C. Jh,et al.  Derivation of Maximum Permissible Concentrations forseveral volatile compounds for water and soil , 1993 .

[3]  Steave H Su,et al.  Development of a refined database of mammalian relative potency estimates for dioxin-like compounds. , 2006, Toxicological sciences : an official journal of the Society of Toxicology.

[4]  R M Putzrath,et al.  Estimating relative potency for receptor-mediated toxicity: reevaluating the toxicity equivalence factor (TEF) model. , 1997, Regulatory toxicology and pharmacology : RTP.

[5]  Glenn W. Suter,et al.  General Introduction to Species Sensitivity Distributions , 2001 .

[6]  Judi L. Durda,et al.  Data Quality Evaluation of Toxicological Studies Used to Derive Ecotoxicological Benchmarks , 2000 .

[7]  U. Tillmann,et al.  A systematic approach for evaluating the quality of experimental toxicological and ecotoxicological data. , 1997, Regulatory toxicology and pharmacology : RTP.

[8]  J. Brodie,et al.  Reef Water Quality Protection Plan 2013. Prioritisation project report , 2014 .

[9]  C. Tohyama,et al.  The 2005 World Health Organization reevaluation of human and Mammalian toxic equivalency factors for dioxins and dioxin-like compounds. , 2006, Toxicological sciences : an official journal of the Society of Toxicology.

[10]  T. Koontz,et al.  Reducing Nonpoint Source Pollution Through Collaboration: Policies and Programs Across the U.S. States , 2008, Environmental management.

[11]  D Raha,et al.  Paradigm shift in water environment protection in New South Wales , 2007 .

[12]  Antonio Marcomini,et al.  A Multi-Criteria Decision Analysis based methodology for quantitatively scoring the reliability and relevance of ecotoxicological data. , 2015, The Science of the total environment.

[13]  E. Sigal,et al.  The Use of Toxic Equivalency Factors (TEFs) in Ecological Risk Assessment: Strengths and Limitations , 1999 .

[14]  D. de Zwart,et al.  Complex mixture toxicity for single and multiple species: Proposed methodologies , 2005, Environmental toxicology and chemistry.

[15]  J. Pedersen,et al.  Organophosphorus insecticides in agricultural and residential runoff: field observations and implications for total maximum daily load development. , 2006, Environmental science & technology.

[16]  P. Scott,et al.  The Use of Toxic Equivalency Factor Distributions in Probabilistic Risk Assessments for Dioxins, Furans, and PCBs , 2003, Journal of toxicology and environmental health. Part A.

[17]  Marlene Ågerstrand,et al.  Bad Reporting or Bad Science? Systematic Data Evaluation as a Means to Improve the Use of Peer-Reviewed Studies in Risk Assessments of Chemicals , 2014 .

[18]  Thomas Hartung,et al.  "ToxRTool", a new tool to assess the reliability of toxicological data. , 2009, Toxicology letters.

[19]  Michael St J Warne,et al.  Evaluation of Criteria Used to Assess the Quality of Aquatic Toxicity Data , 2005, Integrated environmental assessment and management.

[20]  S. Safe,et al.  Hazard and risk assessment of chemical mixtures using the toxic equivalency factor approach. , 1998, Environmental health perspectives.

[21]  Timo Hamers,et al.  The potentially affected fraction as a measure of ecological risk , 2002 .