scholarly journals Improved component-based methods for mixture risk assessment are key to characterize complex chemical pollution in surface waters

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Leo Posthuma ◽  
Rolf Altenburger ◽  
Thomas Backhaus ◽  
Andreas Kortenkamp ◽  
Christin Müller ◽  
...  
Keyword(s):  
Water Quality ◽  
Risk Assessment ◽  
Mixture Toxicity ◽  
Chemical Pollution ◽  
Management Planning ◽  
Collaborative Project ◽  
Water Quality Protection ◽  
Current Guidance ◽  
Mixture Risk Assessment ◽  
Selection Of

Abstract The present monitoring and assessment of water quality problems fails to characterize the likelihood that complex mixtures of chemicals affect water quality. The European collaborative project SOLUTIONS suggests that this likelihood can be estimated, amongst other methods, with improved component-based methods (CBMs). The use of CBMs is a well-established practice in the WFD, as one of the lines of evidence to evaluate chemical pollution on a per-chemical basis. However, this is currently limited to a pre-selection of 45 and approximately 300 monitored substances (priority substances and river basin-specific pollutants, respectively), of which only a few actually co-occur in relevant concentrations in real-world mixtures. Advanced CBM practices are therefore needed that consider a broader, realistic spectrum of chemicals and thereby improve the assessment of mixture impacts, diagnose the causes of observed impacts and provide more useful water management information. Various CBMs are described and illustrated, often representing improvements of well-established methods. Given the goals of the WFD and expanding on current guidance for risk assessment, these improved CBMs can be applied to predicted or monitored concentrations of chemical pollutants to provide information for management planning. As shown in various examples, the outcomes of the improved CBMs allow for the evaluation of the current likelihood of impacts, of alternative abatement scenarios as well as the expected consequences of future pollution scenarios. The outputs of the improved CBMs are useful to underpin programmes of measures to protect and improve water quality. The combination of CBMs with effect-based methods (EBMs) might be especially powerful to identify as yet underinvestigated emerging pollutants and their importance in a mixture toxicity context. The present paper has been designed as one in a series of policy briefs to support decisions on water quality protection, monitoring, assessment and management under the European Water Framework Directive (WFD).

scholarly journals A holistic approach is key to protect water quality and monitor, assess and manage chemical pollution of European surface waters

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Leo Posthuma ◽  
John Munthe ◽  
Jos van Gils ◽  
Rolf Altenburger ◽  
Christin Müller ◽  
...  
Keyword(s):  
Water Quality ◽  
Surface Waters ◽  
Complex Mixture ◽  
Water System ◽  
Basic Feature ◽  
System Level ◽  
Chemical Pollution ◽  
Large Set ◽  
The European Union ◽  
Water Quality Protection

Abstract Chemical pollution of surface waters is a societal concern around the globe. Key problems in current water quality protection, assessment and management are the narrow focus on a small fraction of the chemicals in commerce, concerns for increasingly diverse chemical emissions, and lack of effective diagnosis and management approaches. In reply, three key concepts to address these challenges were developed and tested. The approaches were developed in the context of the European Union Water Framework Directive, based on principles such as the DPSIR-causal framework (Drivers, Pressure, Status, Impact and Response) and the basic feature that water protection and management should be based on a water-system level approach. Collaborative actions of researchers and stakeholders resulted in: (1) an operationalization and implementation of the solution-focused risk assessment paradigm as proposed in 2009, to improve the utility of risk assessments, (2) the provision of a large set of tools and services to prevent, monitor, assess and manage complex mixture pollution problems, and (3) a strategy and a database on intervention options. These three elements were recognized as core elements to help protecting and improving water quality. Although the methods were developed in the context of water quality problems in Europe, the three elements can be applied globally in water quality protection and management.

scholarly journals Mixture risks threaten water quality: the European Collaborative Project SOLUTIONS recommends changes to the WFD and better coordination across all pieces of European chemicals legislation to improve protection from exposure of the aquatic environment to multiple pollutants

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Andreas Kortenkamp ◽  
Michael Faust ◽  
Thomas Backhaus ◽  
Rolf Altenburger ◽  
Martin Scholze ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Risk Assessments ◽  
Industrial Chemicals ◽  
Assessment Practice ◽  
Management Options ◽  
Collaborative Project ◽  
Chemical Monitoring ◽  
Essential Input ◽  
Fit For Purpose ◽  
Mixture Risk Assessment

Abstract Evidence is mounting that chemicals can produce joint toxicity even when combined at levels that singly do not pose risks. Environmental Quality Standards (EQS) defined for single pollutants under the Water Framework Directive (WFD) do not protect from mixture risks, nor do they enable prioritization of management options. Despite some provisions for mixtures of specific groups of chemicals, the WFD is not fit for purpose for protecting against or managing the effects of coincidental mixtures of water-borne pollutants. The conceptual tools for conducting mixture risk assessment are available and ready for use in regulatory and risk assessment practice. Extension towards impact assessment using cumulative toxic unit and mixture toxic pressure analysis based on chemical monitoring data or modelling has been suggested by the SOLUTIONS project. Problems exist in the availability of the data necessary for mixture risk assessments. Mixture risk assessments cannot be conducted without essential input data about exposures to chemicals and their toxicity. If data are missing, mixture risk assessments will be biassed towards underestimating risks. The WFD itself is not intended to provide toxicity data. Data gaps can only be closed if proper feedback links between the WFD and other EU regulations for industrial chemicals (REACH), pesticides (PPPR), biocides (BPR) and pharmaceuticals are implemented. Changes of the WFD alone cannot meet these requirements. Effect-based monitoring programmes developed by SOLUTIONS should be implemented as they can capture the toxicity of complex mixtures and provide leads for new candidate chemicals that require attention in mixture risk assessment. Efforts of modelling pollutant levels and their anticipated mixture effects in surface water can also generate such leads. New pollutant prioritization schemes conceived by SOLUTIONS, applied in the context of site prioritization, will help to focus mixture risk assessments on those chemicals and sites that make substantial contributions to mixture risks.

scholarly journals Exploring the ‘solution space’ is key: SOLUTIONS recommends an early-stage assessment of options to protect and restore water quality against chemical pollution

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Leo Posthuma ◽  
Thomas Backhaus ◽  
Juliane Hollender ◽  
Dirk Bunke ◽  
Werner Brack ◽  
...  
Keyword(s):  
Water Quality ◽  
Risk Assessment ◽  
Early Stage ◽  
Solution Space ◽  
River Basin Management ◽  
Chemical Pollution ◽  
Technical Solution ◽  
Local Pollution ◽  
Problem Description ◽  
Solution Focused

Abstract Present evaluations of chemical pollution in European surface and groundwater bodies focus on problem description and chemical classification of water quality. Surprisingly, relatively low attention has been paid to solutions of chemical pollution problems when those are encountered. Based on evaluations of current practices and available approaches, we suggest that water quality protection, monitoring, assessment and management of chemical pollution can be improved by implementing an early-stage exploration of the ‘solution space’. This follows from the innovative paradigm of solution-focused risk assessment, which was developed to improve the utility of risk assessments. The ‘solution space’ is defined as the set of potential activities that can be considered to protect or restore the water quality against hazards posed by chemical pollution. When using the paradigm, upfront exploration of solution options and selecting options that would be feasible given the local pollution context would result in comparative risk assessment outcomes. The comparative outcomes are useful for selecting optimal measures against chemical pollution for management prioritization and planning. It is recommended to apply the solution-focused risk assessment paradigm to improve the chemical pollution information for river basin management planning. To operationalize this, the present paper describes a still-growing database and strategy to find and select technical abatement and/or non-technical solution options for chemical pollution of surface waters. The solutions database and strategy can be applied to help prevent and reduce water quality problems. Various case studies show that implementing these can be effective, and how solution scenarios can be evaluated for their efficacy by comparative exposure and effect assessment.

scholarly journals A note of caution: the threshold of toxicological concern (TTC) is unsuited as a decision rule for deciding whether mixture risk assessment is necessary

2014 ◽  
Author(s):  
Thomas Backhaus
Keyword(s):  
Risk Assessment ◽  
Decision Rule ◽  
Error Propagation ◽  
Statistical Error ◽  
Mixture Toxicity ◽  
Decision Criterion ◽  
Data Gaps ◽  
Threshold Of Toxicological Concern ◽  
Mixture Risk Assessment ◽  
The Eu

The threshold of toxicological concern has been suggested as a decision rule on whether a mixture risk assessment is required. According to the recent opinion on mixture toxicity, published by the EU scientific committees, mixture effects are not to be expected, if the mixture components do not share the same mode or mechanism of action and are present at or below their individual TTCs. This, however, ignores the statistical error propagation that is encountered when handling multi-component chemical mixtures, which results in a huge probability that one or more mixture components are de facto more toxic than estimated by the corresponding TTC. It is hence argued that the TTC is a valuable tool to bridge data gaps in case experimental toxicity data are missing, but it is unsuited without further refinement as a decision criterion on whether a mixture assessment is needed in a given exposure scenario.

scholarly journals A note of caution: the threshold of toxicological concern (TTC) is unsuited as a decision rule for deciding whether mixture risk assessment is necessary

2014 ◽  
Author(s):  
Thomas Backhaus
Keyword(s):  
Risk Assessment ◽  
Decision Rule ◽  
Error Propagation ◽  
Statistical Error ◽  
Mixture Toxicity ◽  
Decision Criterion ◽  
Data Gaps ◽  
Threshold Of Toxicological Concern ◽  
Mixture Risk Assessment ◽  
The Eu

The threshold of toxicological concern has been suggested as a decision rule on whether a mixture risk assessment is required. According to the recent opinion on mixture toxicity, published by the EU scientific committees, mixture effects are not to be expected, if the mixture components do not share the same mode or mechanism of action and are present at or below their individual TTCs. This, however, ignores the statistical error propagation that is encountered when handling multi-component chemical mixtures, which results in a huge probability that one or more mixture components are de facto more toxic than estimated by the corresponding TTC. It is hence argued that the TTC is a valuable tool to bridge data gaps in case experimental toxicity data are missing, but it is unsuited without further refinement as a decision criterion on whether a mixture assessment is needed in a given exposure scenario.

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