“Evidence is mounting that chemicals can produce joint toxicity even when combined at levels that singly do not pose risks,” states a policy briefing produced by the EU-funded SOLUTIONS project and published in the Environmental Sciences Europe journal. But environmental quality standards defined for single pollutants under the directive do not account for mixture risks, “nor do they enable prioritisation of management options,” the paper adds.
It thus concludes that the legislation is, “not fit for purpose for protecting against or managing the effects of coincidental mixtures of water-borne pollutants.”
The tools for conducting risk assessments for mixtures are ready and ready for use, although there are gaps in the data needed to conduct them. This absence would tend to lead to bias towards underestimating risks, says the paper.
Such gaps “can only be closed if proper feedback links” between the WFD and chemicals legislation (REACH, Plant Protection Products Regulation, Biocidal Products Regulation) and pharmaceuticals regulation are implemented, it adds.
These could be filled, in part, by effects-based monitoring and modelling programmes developed by SOLUTIONS, which capture the toxicity of complex mixtures and can provide candidates for regulatory attention.
The paper is one among 15 briefings developed for policymakers, the publication of which in a peer-reviewed open-access journal is “quite unique” according to an accompanying editorial. The briefs are not only intended to influence policy by providing information in a more easily-understandable format but also to encourage researchers to try to translate research into action.
The editorial notes that chemical pollution typically occurs as a complex mixture of substances, which can pose a substantial risk to water quality. Results from both monitoring and modelling found that such mixtures can be important drivers of ecological status.
But only 45 specific priority substances, plus certain chemicals designated for particular catchments, are required to be monitored under the WFD, potentially masking the true condition of water bodies.
“It has been shown that the current practice of limiting the assessment of chemical pollution to a few substances defined as priorities throughout Europe and certain river-basin-specific pollutants is not sufficient for recording pollution as a whole," said SOLUTIONS coordinator Werner Brack. More than 100,000 chemicals end up in water bodies.
The briefs, produced by more than 100 scientists, outline methods and practical solutions for identifying pollutants and assessing the risks presented by cocktail effects.
One brief describes the use of the RiBaTox (River Basin Specific Toxicants assessment and management) tool to solve problems related to the monitoring, modelling, impact assessment and management of chemical mixtures in surface waters. This employs effect-based methods to assess impacts on aquatic organisms and allow toxic loads to be determined, even if the underlying chemicals are unknown or below detection limits.
These methods should be complemented with chemical screening techniques using mass spectrometry to establish the composition of mixtures, detect emerging contaminants and monitor trends.
The project also concluded that a Europe-wide system should be set up to collect and disseminate the data obtained.