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1.
Environ Int ; 179: 108155, 2023 09.
Article in English | MEDLINE | ID: mdl-37688808

ABSTRACT

Aquatic environments are polluted with a multitude of organic micropollutants, which challenges risk assessment due the complexity and diversity of pollutant mixtures. The recognition that certain source-specific background pollution occurs ubiquitously in the aquatic environment might be one way forward to approach mixture risk assessment. To investigate this hypothesis, we prepared one typical and representative WWTP effluent mixture of organic micropollutants (EWERBmix) comprised of 81 compounds selected according to their high frequency of occurrence and toxic potential. Toxicological relevant effects of this reference mixture were measured in eight organism- and cell-based bioassays and compared with predicted mixture effects, which were calculated based on effect data of single chemicals retrieved from literature or different databases, and via quantitative structure-activity relationships (QSARs). The results show that the EWERBmix supports the identification of substances which should be considered in future monitoring efforts. It provides measures to estimate wastewater background concentrations in rivers under consideration of respective dilution factors, and to assess the extent of mixture risks to be expected from European WWTP effluents. The EWERBmix presents a reasonable proxy for regulatory authorities to develop and implement assessment approaches and regulatory measures to address mixture risks. The highlighted data gaps should be considered for prioritization of effect testing of most prevalent and relevant individual organic micropollutants of WWTP effluent background pollution. The here provided approach and EWERBmix are available for authorities and scientists for further investigations. The approach presented can furthermore serve as a roadmap guiding the development of archetypic background mixtures for other sources, geographical settings and chemical compounds, e.g. inorganic pollutants.


Subject(s)
Environmental Pollutants , Databases, Factual , Environmental Pollution , Geography , Quantitative Structure-Activity Relationship
2.
Integr Environ Assess Manag ; 17(3): 498-506, 2021 May.
Article in English | MEDLINE | ID: mdl-33448633

ABSTRACT

The European Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation has been in force since 2007 and is intended to ensure a high level of protection for human health and the environment. The REACH regulation is based on the principle that manufacturers, importers, and downstream users take responsibility for their chemicals. Currently about 23 000 single chemicals are registered within the REACH legislation. A large proportion of substances registered under REACH end up in technical mixtures, intentionally manufactured as such, or generated mixtures containing byproducts of processes. Such mixtures that contain a number of different components are, for example, ink, paint, lacquer, mortar, or cleaning agents. However, REACH focuses on single substances and addresses the safe use of substances as such (e.g., bisphenol A) or substances in mixtures (e.g., bisphenol A used as an antioxidant in mixtures) and in articles (e.g., bisphenol A used as a monomer for polycarbonate production from which greenhouse sheets may be made). In contrast to other substance regulations, under REACH the registrants and downstream users of chemicals are responsible for the risk assessment. According to the REACH regulation, they also have the obligation to derive and communicate safe use conditions for their technical mixtures. Currently, no guidance document and no distinct obligations for an assessment of technical mixtures exist. In light of the available evidence for the joint exposures and effects of chemicals due to co-exposures, the need for approaches for a mixture assessment and improved data communications were highlighted by various stakeholders from industry, European member states, and the European Chemicals Agency (ECHA). The lead component identification (LCID) methodology and the safe use of mixtures information (SUMI) tool were proposed by the European Chemical Industry Council (Cefic) as working tools for the evaluation of the hazard potential, derivation of safe use conditions, and data communication for mixtures along the supply chain. The present paper analyzes the workability and pitfalls of these proposed methodologies from a regulatory perspective, aiming at a safe use of technical mixtures which considers the joint effects and exposures of its components. Integr Environ Assess Manag 2021;17:498-506. © 2021 Umweltbundesamt. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).


Subject(s)
Ecotoxicology , Paint , European Union , Humans , Risk Assessment
3.
Ecotoxicol Environ Saf ; 163: 340-348, 2018 Nov 15.
Article in English | MEDLINE | ID: mdl-30059878

ABSTRACT

Little is known about the ecotoxicity of heterocyclic aromatic hydrocarbons (NSO-HETs) to aquatic organisms. In the environment, NSO-HETs have been shown to occur in a strong association with their unsubstituted carbocyclic analogues, the polycyclic aromatic hydrocarbons (PAH), for which much more information is available. The present study addressed this issue by investigating the toxicity of four selected NSO-HETs in green algae (Desmodesmus subspicatus), daphnids (Daphnia magna) and fish embryos (Danio rerio). The four high molecular weight NSO-HETs dibenz[a,j]acridine (DBA), 7H-dibenzo[c,g]carbazole (DBC), benzo[b]naphtho[2,1-d]thiophene (BNT) and benzo[b]naphtho[1,2-d]furan (BNF) were selected, based on the results of a previous research project, indicating a lack of toxicity data and a high potential for persistence and bioaccumulation. The solubilities of the NSO-HETs in the test media were determined and turned out to be comparatively low (2.7-317 µg/L) increasing in the following order: DBA < BNT « DBC « BNF. Exposure concentrations during the toxicity tests were quantified with GC-MS and decreased strongly possibly due to sorption or metabolising during the test periods (48-96 h). Therefore, the estimated effect concentrations were related to the mean measured concentrations, as endpoints related to nominal concentrations would have underestimated the toxicity many times over. Within the range of the substance solubilities, BNF affected all test organisms with fish embryos being the most sensitive (fish: EC50 6.7 µg/L, algae: EC10 17.8 µg/L, daphnids: EC50 55.8 µg/L). DBC affected daphnids (EC50 2.5 µg/L,) and algae (EC10 3.1 µg/L), but not fish embryos. The lowest toxicity endpoint was observed for BNT affecting only algae (NOEC 0.556 µg/L) and neither daphnids nor fish embryos. DBA did not show any effects on the tested organisms in the range of the water solubility. However, we would expect effects in long-term toxicity studies to fish and aquatic invertebrates for all substances at lower concentrations, which needs further investigation. All four NSO-HETs were identified in mussels (Mytilus edulis) from the German coasts, in green kale (Brassica oleracea var. acephala) and in freshwater harbor sediment in concentrations between 0.07 and 2 µg/kg, highlighting their relevance as environmental contaminants. There is a need to regulate the four NSO-HETs within the REACH regulation due to their intrinsic properties and their environmental relevance. However, acquisition of additional experimental data appears to be pivotal for a regulation under REACH.


Subject(s)
Heterocyclic Compounds/toxicity , Hydrocarbons, Aromatic/toxicity , Water Pollutants, Chemical/toxicity , Animals , Brassica/chemistry , Chlorophyta/drug effects , Daphnia/drug effects , Environmental Monitoring , Europe , Gas Chromatography-Mass Spectrometry , Government Regulation , Heterocyclic Compounds/analysis , Heterocyclic Compounds/chemistry , Hydrocarbons, Aromatic/analysis , Hydrocarbons, Aromatic/chemistry , Molecular Weight , Mytilus , Risk Assessment , Toxicity Tests , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/chemistry , Zebrafish
4.
Water Res ; 140: 56-66, 2018 09 01.
Article in English | MEDLINE | ID: mdl-29684702

ABSTRACT

The aquatic environment is continually exposed to a complex mixture of chemicals, whereby effluents of wastewater treatment plants (WWTPs) are one key source. The aim of the present study was to investigate whether environmental risk assessments (ERAs) addressing individual substances are sufficiently protective for such coincidental mixtures. Based on a literature review of chemicals reported to occur in municipal WWTP effluents and mode-of-action considerations, four different types of mixtures were composed containing human pharmaceuticals, pesticides, and chemicals regulated under REACH. The experimentally determined chronic aquatic toxicity of these mixtures towards primary producers and the invertebrate Daphnia magna could be adequately predicted by the concept of concentration addition, with up to 5-fold overestimation and less than 3-fold underestimation of mixture toxicity. Effluents of a municipal WWTP had no impact on the predictability of mixture toxicity and showed no adverse effects on the test organisms. Predictive ERAs for the individual mixture components based on here derived predicted no effect concentrations (PNECs) and median measured concentrations in WWTP effluents (MCeff) indicated no unacceptable risk for any of the individual chemicals, while MCeff/PNEC summation indicated a possible risk for multi-component mixtures. However, a refined mixture assessment based on the sum of toxic units at species level indicated no unacceptable risks, and allowed for a safety margin of more than factor 10, not taking into account any dilution of WWTP effluents by surface waters. Individual substances, namely climbazole, fenofibric acid and fluoxetine, were dominating the risks of the investigated mixtures, while added risk due to the mixture was found to be low with the risk quotient being increased by less than factor 2. Yet, uncertainty remains regarding chronic mixture toxicity in fish, which was not included in the present study. The number and identity of substances composing environmental mixtures such as WWTP effluents is typically unknown. Therefore, a mixture assessment factor is discussed as an option for a prospective ERA of mixtures of unknown composition.


Subject(s)
Toxicity Tests, Chronic/methods , Wastewater/chemistry , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/toxicity , Animals , Araceae/drug effects , Chlorophyta/drug effects , Daphnia/drug effects , Ecotoxicology/methods , Female , Fenofibrate/analogs & derivatives , Fenofibrate/toxicity , Fluoxetine/toxicity , Imidazoles/toxicity , Male , Pesticides/analysis , Pesticides/toxicity , Pharmaceutical Preparations/analysis , Risk Assessment/methods , Waste Disposal, Fluid
5.
Aquat Toxicol ; 152: 205-14, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24792151

ABSTRACT

A variety of different fungicides are found simultaneously in surface waters, among which demethylase inhibitors (DMIs) are a major group. The joint toxicity of four DMIs from different chemical classes (Fenarimol, Prochloraz, Triadimefon and Pyrifenox) was investigated in the reproduction test with Daphnia magna, following an extended protocol according to ISO 10706. We assessed the toxicity of the DMI mixtures across different endpoints and effect levels and evaluated the predictability of their joint action using Concentration Addition (CA) and Independent Action (IA). The mixture reduced fecundity, delayed molting and caused characteristic malformations in offspring in a concentration-dependent manner which is possibly due to an anti-ecdysteroid action, as previously described for individual DMIs. However, also mixture-specific effects were observed: exposed daphnids reached sexual maturity already after the third juvenile molt, and thus significantly earlier than unexposed daphnids, which needed four juvenile molts to reach maturity. This effect is not caused by any of the DMIs alone. Additionally, the percentage of aborted broods was synergistically higher than expected by either CA or IA. IA underestimates the mixture toxicity for all parameters. The predictive quality of CA differed between life history responses, but was always within a factor of two to the observed toxicity. The parameter "fecundity reduction, counting only normally developed offspring", was the most sensitive endpoint, while the parameter "fecundity reduction, counting all living offspring", was slightly less sensitive. The mixture caused a 90% reduction in fecundity at individual concentrations that only provoke 7% effect or less, which calls for a mixture-specific toxicity assessment of DMI fungicides.


Subject(s)
Daphnia/drug effects , Fungicides, Industrial/toxicity , Models, Theoretical , Water Pollutants, Chemical/toxicity , Animals , Embryo, Nonmammalian/drug effects , Reproduction/drug effects
6.
Environ Sci Technol ; 47(15): 8862-8, 2013 Aug 06.
Article in English | MEDLINE | ID: mdl-23859631

ABSTRACT

Pesticides applied in agriculture can affect the structure and function of nontarget populations at lower doses and for longer timespans than predicted by the current risk assessment frameworks. We identified a mechanism for this observation. The populations of an aquatic invertebrate (Culex pipiens) exposed over several generations to repeated pulses of low concentrations of the neonicotinoid insecticide (thiacloprid) continuously declined and did not recover in the presence of a less sensitive competing species (Daphnia magna). By contrast, in the absence of a competitor, insecticide effects on the more sensitive species were only observed at concentrations 1 order of magnitude higher, and the species recovered more rapidly after a contamination event. The underlying processes are experimentally identified and reconstructed using a simulation model. We conclude that repeated toxicant pulse of populations that are challenged with interspecific competition may result in a multigenerational culmination of low-dose effects.


Subject(s)
Pesticides/toxicity , Animals , Culex/drug effects , Daphnia/drug effects , Dose-Response Relationship, Drug
7.
Environ Toxicol Chem ; 28(6): 1218-26, 2009 Jun.
Article in English | MEDLINE | ID: mdl-19132812

ABSTRACT

Demethylase inhibitors (DMIs) are broad-spectrum fungicides that are ubiquitously used in agriculture and medicine. They comprise chemically heterogeneous substances that share a common biochemical target in fungi, the inhibition of a specific step in sterol biosynthesis. Several DMIs are suspected to disrupt endocrine-mediated processes in a range of organisms and to inhibit ecdysteroid biosynthesis in arthropods. It is unclear, however, whether and, if so, to what extent different DMI fungicides have a similar mode of action in nontarget organisms, which in turn would lead to a common chronic toxicity profile. Therefore, we selected a representative of each of the major DMI classes--the piperazine triforine, the pyrimidine fenarimol, the pyridine pyrifenox, the imidazole prochloraz, and the triazole triadimefon--and comparatively investigated their chronic toxicity to Daphnia magna. No toxicity was detectable up to the limit of solubility of triforine (61 micromol/L). All other DMIs reduced reproductive success by delaying molting and development and by causing severe developmental abnormalities among offspring. Prochloraz was most toxic (median effective concentration [EC50] for fecundity reduction, 0.76 micromol/L), followed by fenarimol (EC50, 1.14 micromol/L), pyrifenox (EC50, 3.15 micromol/L), and triadimefon (EC50, 5.13 micromol/L). Mean effect concentrations for fecundity reduction were related to lipophilicity and followed baseline toxicity. However, triadimefon and fenarimol (but none of the other tested DMIs) caused severe eye malformations among exposed offspring. Affected neonates did survive, but a reduced ecological fitness can be assumed. Offspring exposed to fenarimol in mater matured earlier. The investigated different life-history parameters were affected in a substance-specific manner. These qualitatively different toxicity profiles suggest additional, substance-specific mechanisms of action in D. magna that probably are related to an antiecdysteroid action.


Subject(s)
Enzyme Inhibitors/toxicity , Enzymes/drug effects , Fungicides, Industrial/toxicity , Water Pollutants, Chemical/toxicity , Animals , Daphnia , Enzyme Inhibitors/chemistry , Eye/drug effects , Eye/growth & development , Fungicides, Industrial/chemistry , Molecular Structure , Water Pollutants, Chemical/chemistry
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