Determining the toxicity of organic compounds to the nematode Caenorhabditis elegans based on aqueous concentrations.

Caenorhabditis elegans is used for assessing the toxicity of chemicals in aqueous medium. However, chemicals can absorb to the bacterial food, which reduces the freely dissolved concentrations of the tested compounds. Thus, based on total or nominal concentrations, toxicity is underestimated, resulting in misleading assumptions on toxicity mechanisms or comparisons to other test organisms.

Closed aerobic biodegradation kinetics test with activated sludge and low concentration chemical mixtures.

The activated sludge process at wastewater treatment plants is important to prevent discharge of organic pollutants to the environment. Determination of biodegradation kinetics in activated sludge is challenging for mixtures that cover a diverse range of structures. The aims of this study were to (1) design a closed aerobic biodegradation batch test with activated sludge and (2) develop a sample preparation procedure that is compatible with LC-MS and Solid Phase Microextraction (SPME) coupled to GC-MS.

Biodegradation Kinetics of Fragrances, Plasticizers, UV Filters, and PAHs in a Mixture─Changing Test Concentrations over 5 Orders of Magnitude.

Biodegradation of organic chemicals emitted to the environment is carried out by mixed microbial communities growing on multiple natural and xenobiotic substrates at low concentrations. This study aims to (1) perform simulation type biodegradation tests at a wide range of mixture concentrations, (2) determine the concentration effect on the biodegradation kinetics of individual chemicals, and (3) link the mixture concentration and degradation to microbial community dynamics. Two hundred ninety-four parallel test systems were prepared using wastewater treatment plant effluent as inoculum and passive dosing to add a mixture of 19 chemicals at 6 initial concentration levels (ng/L to mg/L).

Bedform characteristics and biofilm community development interact to modify hyporheic exchange.

The physical and biological attributes of riverine ecosystems interact in a complex manner which can affect the hydrodynamic behaviour of the system. This can alter the mixing characteristics of a river at the sediment-water interface. Research on hyporheic exchange has increased in recent years driven by a greater appreciation for the importance of this dynamic ecotone in connecting and regulating river systems.

Key Opportunities to Replace, Reduce, and Refine Regulatory Fish Acute Toxicity Tests.

Fish acute toxicity tests are conducted as part of regulatory hazard identification and risk-assessment packages for industrial chemicals and plant protection products. The aim of these tests is to determine the concentration which would be lethal to 50% of the animals treated. These tests are therefore associated with suffering in the test animals, and Organisation for Economic Co-operation and Development test guideline 203 (fish, acute toxicity) studies are the most widely conducted regulatory vertebrate ecotoxicology tests for prospective chemical safety assessment.

Comparison of passive-dosed and solvent spiked exposures of pro-carcinogen, benzo[a]pyrene, to human lymphoblastoid cell line, MCL-5.

Genotoxicity testing methods in vitro provide a means to predict the DNA damaging effects of chemicals on human cells. This is hindered in the case of hydrophobic test compounds, however, which will partition to in vitro components such as plastic-ware and medium proteins, in preference to the aqueous phase of the exposure medium. This affects the freely available test chemical concentration, and as this freely dissolved aqueous concentration is that bioavailable to cells, it is important to define and maintain this exposure.

Estimation of the Contribution Made to Down-the-Drain Emissions of D5 by Personal Care Product Categories in the European Union.

Aquatic risk assessment of personal care chemicals requires quantifying the contribution of all product types containing these ingredients to down-the-drain emissions. We developed a probabilistic model framework embracing stochastic variability associated with individual consumers and their behaviors in the European Union, as well as other sources of uncertainty related to losses following applications (e.g.

Spatial and temporal variability in the potential of river water biofilms to degrade p-nitrophenol.

In order to predict the fate of chemicals in the environment, a range of regulatory tests are performed with microbial inocula collected from environmental compartments to investigate the potential for biodegradation. The abundance and distribution of microbes in the environment is affected by a range of variables, hence diversity and biomass of inocula used in biodegradation tests can be highly variable in space and time. The use of artificial or natural biofilms in regulatory tests could enable more consistent microbial communities be used as inocula, in order to increase test consistency.

Advancing the 3Rs in regulatory ecotoxicology: A pragmatic cross-sector approach.

The ecotoxicity testing of chemicals for prospective environmental safety assessment is an area in which a high number of vertebrates are used across a variety of industry sectors. Refining, reducing, and replacing the use of animals such as fish, birds, and amphibians for this purpose addresses the ethical concerns and the increasing legislative requirements to consider alternative test methods. Members of the UK-based National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) Ecotoxicology Working Group, consisting of representatives from academia, government organizations, and industry, have worked together over the past 6 y to provide evidence bases to support and advance the application of the 3Rs in regulatory ecotoxicity testing.

Application of the Activity Framework for Assessing Aquatic Ecotoxicology Data for Organic Chemicals.

Toxicological research in the 1930s gave the first indications of the link between narcotic toxicity and the chemical activity of organic chemicals. More recently, chemical activity has been proposed as a novel exposure parameter that describes the fraction of saturation and that quantifies the potential for partitioning and diffusive uptake. In the present study, more than 2000 acute and chronic algal, aquatic invertebrates and fish toxicity data, as well as water solubility and melting point values, were collected from a series of sources.

Characterization of para-Nitrophenol-Degrading Bacterial Communities in River Water by Using Functional Markers and Stable Isotope Probing.

Microbial degradation is a major determinant of the fate of pollutants in the environment. para-Nitrophenol (PNP) is an EPA-listed priority pollutant with a wide environmental distribution, but little is known about the microorganisms that degrade it in the environment. We studied the diversity of active PNP-degrading bacterial populations in river water using a novel functional marker approach coupled with [(13)C6]PNP stable isotope probing (SIP).

Refinement of biodegradation tests methodologies and the proposed utility of new microbial ecology techniques.

Society's reliance upon chemicals over the last few decades has led to their increased production, application and release into the environment. Determination of chemical persistence is crucial for risk assessment and management of chemicals. Current established OECD biodegradation guidelines enable testing of chemicals under laboratory conditions but with an incomplete consideration of factors that can impact on chemical persistence in the environment.

Measurement of cyclic volatile methylsiloxanes in the aquatic environment using low-density polyethylene passive sampling devices using an in-field calibration study--challenges and guidance.

Cyclic volatile methylsiloxanes (cVMS) are used in personal care products and are hydrophobic, volatile and persistent. Their environmental water concentrations are low and are difficult to detect using conventional sampling methods. This study shows the potential of passive sampling for cVMS.

Accounting for dissociation and photolysis: a review of the algal toxicity of triclosan.

Triclosan, an antimicrobial agent commonly used in down-the-drain consumer products, is toxic to freshwater microalgae. However, the rapid photolysis and pH-dependent dissociation of this compound may give rise to uncertainty in growth inhibition tests with freshwater microalgae, if these are not well characterized. Methods are presented to minimize these uncertainties by stabilizing pH with an organic buffering agent (Bis-Tris) and by the application of ultraviolet (UV) covers to remove UV wavelengths.

Accounting for intended use application in characterizing the contributions of cyclopentasiloxane (D5) to aquatic loadings following personal care product use: antiperspirants, skin care products and hair care products.

Decamethylcyclopentasiloxane, commonly known as D5 (cyclopentasiloxane) has a wide application of use across a multitude of personal care product categories. The relative volatility of D5 is one of the key properties attributed to this substance that provide for the derived performance benefits from the use of this raw material in personal care formulations. On this basis, rapid evaporative loss following use of many products comprising D5 is expected following typical use application and corresponding wear time.

Monitoring and modelling of siloxanes in a sewage treatment plant in the UK.

Monitoring of cyclic volatile methylsiloxanes (cVMS) carried out at Anglian Water's Broadholme sewage treatment plant (STP) is described. The method deployed used headspace gas chromatography/mass spectrometry (HS-GC/MS) and the addition of isotopically labelled cVMS to correct for partitioning in samples containing high levels of particulate and dissolved organic carbon. The method was capable of measuring cVMS in raw sewage samples, with recoveries of 80%, 85% and 71% respectively, for D4, D5 and D6.

Simulated use and wash-off release of decamethylcyclopentasiloxane used in anti-perspirants.

The cyclic volatile methylsiloxane, decamethylcyclopentasiloxane (D5) is used in a large variety of personal care products. Based on the physical-chemical properties of D5, it is likely that losses due to volatilisation may strongly influence the levels entering the aquatic environment. The aim of this study was to quantify the amount of D5 in waste wash water, after typical application and use in a range of deodorant and anti-perspirant (AP) products.

Prioritising chemicals used in personal care products in China for environmental risk assessment: application of the RAIDAR model.

China represents a significant market for the sale of personal care products (PCPs). Given the continuous emission of hundreds of chemicals used in PCPs to waste water and the aquatic environment after regular use, methods for prioritising the environmental risk assessment for China are needed. In an effort to assess the prioritisation of chemicals used in PCPs in China, we have identified the chemical ingredients used in 2500 PCPs released to the Chinese market in 2009, and estimated the annual emission of these chemicals.

Cyclic volatile methylsiloxane bioaccumulation in flounder and ragworm in the Humber Estuary.

Cyclic volatile methylsiloxanes are being subjected to regulatory scrutiny as possible PBT chemicals. The investigation of bioaccumulation has yielded apparently contradictory results, with high laboratory fish bioconcentration factors on the one hand and low field trophic magnification factors on the other. In this study, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were studied along with polychlorinated biphenyls (PCBs) in sediments, ragworm, and flounder from six sites in the Humber Estuary.

Global distribution of linear and cyclic volatile methyl siloxanes in air.

The global distribution of linear and cyclic volatile methyl silxoanes (VMS) was investigated at 20 sites worldwide, including 5 locations in the Arctic, using sorbent-impregnated polyurethane foam (SIP) disk passive air samplers. Cyclic VMS are currently being considered for regulation because they are high production volume chemicals that are potentially persistent, bioaccumulative, and toxic. Linear and cyclic VMS (including L3, L4, L5, D3, D4, D5, and D6) were analyzed for in air at all urban, background, and Arctic sites.

Determination of decamethylcyclopentasiloxane in river and estuarine sediments in the UK.

Robust analytical procedures for the measurement of decamethylcyclopentasiloxane (D₅) in river and estuarine sediments and their application in determining environmental concentrations in the UK are presented for the first time in this work. Novel approaches to minimise commonly reported artefacts are utilised, improving the confidence in the concentrations of D₅ reported. Accelerated solvent extraction (ASE) and liquid-solid extraction methods are compared.

Effects of triclosan on soil microbial respiration.

The antimicrobial substance triclosan has widespread use in personal care products and can enter the terrestrial environment if sewage sludge is applied to soil. The inhibitory effects of triclosan on basal and substrate-induced respiration (SIR) of three different soils were investigated. Soils were dosed and later redosed with four nominal triclosan concentrations, and respiration rates were measured over time.

The use of the zebrafish (Danio rerio) embryo for the acute toxicity testing of surfactants, as a possible alternative to the acute fish test.

At present, the acute toxicity of chemicals to fish is most commonly estimated by means of a short-term test on juvenile or adult animals (OECD TG 203). Although, over the last few years, the numbers used have been reduced due to the implementation of the Three Rs (Reduction, Refinement and Replacement), significant numbers of fish are still used in acute toxicity tests. With the introduction of the new European Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) system, this number is likely to increase dramatically.

Concentrations and fate of decamethylcyclopentasiloxane (D(5)) in the atmosphere.

Decamethylcyclopentasiloxane (D(5)) is a volatile compound used in personal care products that is released to the atmosphere in large quantities. Although D(5) is currently under consideration for regulation, there have been no field investigations of its atmospheric fate. We employed a recently developed, quality assured method to measure D(5) concentration in ambient air at a rural site in Sweden.

Predicting accurate and ecologically relevant regional scale concentrations of triclosan in rivers for use in higher-tier aquatic risk assessments.

Triclosan (TCS) is used in a range of domestic products and may reach aquatic environments after disposal "down-the-drain". Reach-specific TCS concentrations were predicted using the stochastic water quality model LF2000-WQX for two heavily urbanised regions in England, encompassing some of the most densely populated areas (including London and Birmingham). The model was calibrated using effluent TCS concentration data derived from a national monitoring programme which included 21 sewage treatment plants (STPs).