Risk from unintentional environmental mixtures in EU surface waters is dominated by a limited number of substances

The European regulatory system for plant protection products-cause of a "Silent Spring" or highly advanced and protective?

Current publications that are shaping public perception repeatedly claim that residues of plant protection products (PPP) in the environment demonstrate gaps in assessing the exposure and effects of PPP, allegedly revealing the inability of the European regulatory system to prevent environmental contamination and damage such as biodiversity decline. The hypothesis is that environmental risk assessments rely on inappropriate predictive models that underestimate exposure and do not explicitly account for the impact of combinations of environmental stressors and physiological differences in stress responses. This article puts this criticism into context to allow for a more balanced evaluation of the European regulatory system for PPP. There is broad consensus that the decline in biodiversity is real. This article analyzed current literature for causes of this decline and of chemical contamination. The main drivers identified were land use changes and structural uniformity of agricultural landscapes or multiple contaminants emitted by various sources such as wastewater discharge systems. Comparing measured environmental concentrations from published monitoring studies with exposure predictions from the regulatory risk assessment reveals only slight occasional exceedances for a few environmental scenarios and compounds. Therefore, the call for greater conservatism in the European authorization process for PPPs will not lead to an improvement in the environmental situation. We suggest enhancing landscape diversity through the European Union Common Agricultural Policy and reducing contamination from wastewater and farmyard effluents. The current regulatory risk management toolbox should be expanded to include flexible localized mitigation measures and treatment options to reduce applied amounts and off-target exposure.

Illegal Substance Analysis and Environmental Risk Assessment in Küçük Menderes River, Important Basin of the Aegean Region

Water-based studies have come into prominence for illegal substance monitoring. There are limited studies on the detection of these substances in the surface waters as opposed to wastewater. This study aims to evaluate amphetamine, benzoylecgonine, cocaine, codeine, 3,4-methylenedioxy-N-methylamphetamine, morphine, and 11-nor-Δ9- tetrahydrocannabinol-9-carboxylic acid in the Küçük Menderes (KM) River at four different stations during three different periods and assess the environmental risks. Environmental risk assessment of psychoactive substances based on the calculation of Risk Quotients (RQ) were evaluated. RQ values for amphetamine and benzoylecgonine were < 0.01 at all sampling points during all sampling periods, indicating little risk for aquatic life. Cocaine was found as environmentally high risk (RQ > 1) based on its RQ values of 1.22 and 1.37 at KM-01 and KM-02 sampling points. This research is the first report to investigate the presence of psychoactive substances and define the environmental risks of these substances in Türkiye.

Assessing the impact of different assumptions on the size of a Mixture Assessment Factor (MAF) for chemical mixtures in surface waters using data from three recent monitoring studies

Mixture Assessment Factors (MAFs) have been proposed in the European Union (EU) as a rapid and simple way of protecting aquatic organisms from the combined effects of unintentional chemical mixtures when regulating industrial chemicals under the REACH (EU Regulation on the registration, evaluation, authorisation, and restriction of chemicals) program. A wide range of values has been suggested for the MAF including values of 20 or larger. In this paper we performed a series of case studies using composition data from 46,546 mixtures reported in three surveys of chemicals in EU surface waters. We determine that much of the evidence indicating a need for MAF values of five or greater is the result of assumptions on the impacts of future mitigations and screening assumptions used when determining combined risk. In this paper we present estimates of the MAF values that are based on more realistic assumptions for the impacts of future mitigation and mixture risk assessments that use data on the specific endpoints caused by chemicals and the modes-of-action (MoAs) by which the endpoints occur. We show that smaller MAFs may be sufficient to protect ecological receptors in >95 % of the mixtures reported in each of the three surveys. We also show that generic MAFs could be tailored to individual chemicals based on the chemicals endpoints and MoAs. Finally, we demonstrate that the use of a large MAF could result in unnecessary concerns for chemical mixtures in many surface waters. These findings suggest that caution should be taken in the use of large MAFs in regulations.

Predictive value of the ToxCast/Tox21 high throughput toxicity screening data for approximating in vivo ecotoxicity endpoints and ecotoxicological risk in eco- surveillance applications

Ecotoxicology has long relied on assessing the hazard potential of chemicals through traditional in vivo testing methods to understand the possible risk exposure could pose to ecological taxa. In the past decade, the development of non-animal new approach methods (NAMs) for assessing chemical hazard and risk has quickly grown. These methods are often cheaper and faster than traditional toxicity testing, and thus are amenable to high-throughput toxicity testing (HTT), resulting in large datasets. The ToxCast/Tox21 HTT programs have produced in vitro data for thousands of chemicals covering a large space of biological activity. The relevance of these data to in vivo mammalian toxicity has been much explored. Interest has also grown in using these data to evaluate the risk of environmental exposures to taxa of ecological importance such as fish, aquatic invertebrates, etc.; particularly for the purpose of estimating the risk of exposure from real-world complex mixtures. Understanding the relationship and relative sensitivity of NAMs versus standardized ecotoxicological whole organism models is a key component of performing reliable read-across from mammalian in vitro data to ecotoxicological in vivo data. In this work, we explore the relationship between in vivo ecotoxicity data from several publicly available databases and the ToxCast/Tox21 data. We also performed several case studies in which we compare how using different ecotoxicity datasets, whether traditional or ToxCast-based, affects risk conclusions based on exposure to complex mixtures derived from existing large-scale chemical monitoring data. Generally, predictive value of ToxCast data for traditional in vivo endpoints (EPs) was poor (r ≤ 0.3). Risk conclusions, including identification of different chemical risk drivers and prioritized monitoring sites, were different when using HTT data vs. traditional in vivo data.

Handling concentration data below the analytical limit in environmental mixture risk assessment: A case-study on pesticide river monitoring

Aquatic organisms are exposed to ever-changing complex mixtures of chemicals throughout their lifetime. Component-Based Mixture Risk Assessment (CBMRA) is a well-established methodology for water contaminant-mixture management, the use of which is growing due to improved access to reference ecotoxicity data and extensive monitoring datasets. It enables the translation of measured exposure concentrations of chemicals into biological effect values, and thus to quantitatively estimate the risk of the whole water sample (i.e., as a mixture). However, many factors can bias the final risk decision by impacting the risk metric components; thus, a careful design of the CBMRA is needed, taking into primary consideration the specific features of the dataset and mixture risk assessment assignments. This study systematically addressed the effects of the most common approaches used for handling the concentrations of chemicals below the limit of detection/quantification (LOD/LOQ) in CBMRA. The main results included: i) an informed CBMRA procedure that enables the tracking of the risk decisions triggered by substances below LOD/LOQ, ii) a conceptual map and guidance criteria to support the selection of the most suitable approach for specific scenarios and related interpretation; iii) a guided implementation of the informed CBMRA on dataset of pesticide concentrations in Italian rivers in 2020 (702,097 records).

Assessment of the contribution of surfactants to mixture toxicity in French surface waters

Surfactants are widely used 'down-the-drain' chemicals with the potential to occur at high concentrations in local water bodies and to be part of unintentional environmental mixtures. Recently, increased regulatory focus has been placed on the impacts of complex mixtures in aquatic environments and the substances that are likely to drive mixture risk. This study assessed the contribution of surfactants to the total mixture pressure in freshwater ecosystems. Environmental concentrations, collated from existing French monitoring data, were combined with estimated ecotoxicological thresholds to calculate hazard quotients (HQ) for each substance, and hazard indices (HI) for each mixture. Two scenarios were investigated to correct for concentrations below the limit of quantification (LOQ) in the dataset. The first (best-case) scenario assumed all values Collapse

Key Words

• Aquatic
• Complex mixtures
• Concentration addition
• Environmental monitoring
• Risk assessment
• Surfactants

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Affiliation(s)

Nathalie Briels ARCHE Consulting, Liefkensstraat 35d, 9032 Gent (Wondelgem), Belgium
Charlotte Nys ARCHE Consulting, Liefkensstraat 35d, 9032 Gent (Wondelgem), Belgium
Karel P J Viaene ARCHE Consulting, Liefkensstraat 35d, 9032 Gent (Wondelgem), Belgium
Frederik Verdonck ARCHE Consulting, Liefkensstraat 35d, 9032 Gent (Wondelgem), Belgium
Erin M Maloney Shell Global Solutions International B.V., Carel van Bylandtlaan 16, 2596 HR Den Haag, the Netherlands
James Dawick Innospec Limited, Innospec Manufacturing Park, Oil G Sites Road Ellesmere Port, Cheshire CH65 4EY, UK
Chiara Maria Vitale Procter & Gamble, Brussels Innovation Centre, Temselaan 100, B-1853 Strombeek-Bever, Belgium
Diederik Schowanek Procter & Gamble, Brussels Innovation Centre, Temselaan 100, B-1853 Strombeek-Bever, Belgium.

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Evaluation of mixture toxicity literature and chemical space: a data centric approach

Using the Abstract Sifter tool to analyse PubMed, we reveal published mixture related research most commonly relates to water pollutants, pesticides, environmental pollutants, insecticides, soil pollutants, and chemicals described as persistent, bioaccumulative, and toxic. Furthermore, we discern individual chemicals that also identify as priority chemicals in biomonitoring initiatives and using an ontology-based chemical classification, at the level of the chemical subclass, found these priority chemicals overlap with just 9% of the REACH chemical space.

Analysis and management of herbicidal mixtures in a high-intensity agricultural landscape in Belgium

Water bodies located in anthropogenically influenced environments, such as agricultural landscapes, may be exposed to different chemicals simultaneously or sequentially. Yet, current environmental risk assessments focus on single active substances for unintended mixtures. For 3.5 years, the present study monitored the mixture of herbicides, within an intensively managed agricultural catchment, accompanied by a stewardship program. Twelve herbicides and one metabolite were monitored on a daily to sub-daily basis, generating a unique, high temporal resolution data set, enabling an assessment of cumulative exposure in a worst-case scenario. Analyses focused on the number of events at which the herbicide mixture concentration exceeded the regulatory accepted concentration for algae and macrophytes, based on concentration addition, and the potential factors influencing the frequency of these events are considered. A low number of individual herbicides drove the toxicity and only two of these overlapped for the two organism groups, algae and macrophytes. The observed exceedance events coincided with seasonal influences, and low rainfall during the 2011 season correlated with a highly reduced number of these events. The major influence was found to be the implementation of the stewardship program, which directed farmers to use more advanced farming techniques, avoid spillages, and other point sources. The number of exceedance events was reduced by more than half for algae (9% of the daily mean samples in 2010 and 4% in 2013) and by approximately 10 times for macrophytes (36% in 2010 to 3% in 2013). This high-resolution monitoring data set illustrates how knowledge of the influencing factors can help reduce unintended exposure to chemicals and achieve real-world improvements. Overall, a single-substance assessment is protective of mixture effects. Where mixture effects do play a role, local measures to manage point sources are more effective than changes to the desk-based environmental risk assessments that focus on diffuse sources. Integr Environ Assess Manag 2023;19:1297-1306. © 2022 Cambridge Environmental Assessments RSK ADAS Ltd and Bayer AG. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).