The SEURAT-1 approach towards animal free human safety assessment.

SEURAT-1 is a European public-private research consortium that is working towards animal-free testing of chemical compounds and the highest level of consumer protection. A research strategy was formulated based on the guiding principle to adopt a toxicological mode-of-action framework to describe how any substance may adversely affect human health.The proof of the initiative will be in demonstrating the applicability of the concepts on which SEURAT-1 is built on three levels:(i) Theoretical prototypes for adverse outcome pathways are formulated based on knowledge already available in the scientific literature on investigating the toxicological mode-of-actions leading to adverse outcomes (addressing mainly liver toxicity);(ii)adverse outcome pathway descriptions are used as a guide for the formulation of case studies to further elucidate the theoretical model and to develop integrated testing strategies for the prediction of certain toxicological effects (i.e., those related to the adverse outcome pathway descriptions);(iii) further case studies target the application of knowledge gained within SEURAT-1 in the context of safety assessment. The ultimate goal would be to perform ab initio predictions based on a complete understanding of toxicological mechanisms. In the near-term, it is more realistic that data from innovative testing methods will support read-across arguments. Both scenarios are addressed with case studies for improved safety assessment. A conceptual framework for a rational integrated assessment strategy emerged from designing the case studies and is discussed in the context of international developments focusing on alternative approaches for evaluating chemicals using the new 21st century tools for toxicity testing.

SEURAT: Safety Evaluation Ultimately Replacing Animal Testing--recommendations for future research in the field of predictive toxicology.

The development of non-animal methodology to evaluate the potential for a chemical to cause systemic toxicity is one of the grand challenges of modern science. The European research programme SEURAT is active in this field and will conclude its first phase, SEURAT-1, in December 2015. Drawing on the experience gained in SEURAT-1 and appreciating international advancement in both basic and regulatory science, we reflect here on how SEURAT should evolve and propose that further research and development should be directed along two complementary and interconnecting work streams. The first work stream would focus on developing new 'paradigm' approaches for regulatory science. The goal here is the identification of 'critical biological targets' relevant for toxicity and to test their suitability to be used as anchors for predicting toxicity. The second work stream would focus on integration and application of new approach methods for hazard (and risk) assessment within the current regulatory 'paradigm', aiming for acceptance of animal-free testing strategies by regulatory authorities (i.e. translating scientific achievements into regulation). Components for both work streams are discussed and may provide a structure for a future research programme in the field of predictive toxicology.

Consensus report on the future of animal-free systemic toxicity testing.

Since March 2013, animal use for cosmetics testing for the European market has been banned. This requires a renewed view on risk assessment in this field. However, in other fields as well, traditional animal experimentation does not always satisfy requirements in safety testing, as the need for human-relevant information is ever increasing. A general strategy for animal-free test approaches was outlined by the US National Research Council`s vision document for Toxicity Testing in the 21st Century in 2007. It is now possible to provide a more defined roadmap on how to implement this vision for the four principal areas of systemic toxicity evaluation: repeat dose organ toxicity, carcinogenicity, reproductive toxicity and allergy induction (skin sensitization), as well as for the evaluation of toxicant metabolism (toxicokinetics) (Fig. 1). CAAT-Europe assembled experts from Europe, America and Asia to design a scientific roadmap for future risk assessment approaches and the outcome was then further discussed and refined in two consensus meetings with over 200 stakeholders. The key recommendations include: focusing on improving existing methods rather than favoring de novo design; combining hazard testing with toxicokinetics predictions; developing integrated test strategies; incorporating new high content endpoints to classical assays; evolving test validation procedures; promoting collaboration and data-sharing of different industrial sectors; integrating new disciplines, such as systems biology and high throughput screening; and involving regulators early on in the test development process. A focus on data quality, combined with increased attention to the scientific background of a test method, will be important drivers. Information from each test system should be mapped along adverse outcome pathways. Finally, quantitative information on all factors and key events will be fed into systems biology models that allow a probabilistic risk assessment with flexible adaptation to exposure scenarios and individual risk factors.

Occurrence and distribution of benzothiazole in the Schwarzbach watershed (Germany).

This study quantifies the regional distribution of the micropollutant benzothiazole (BT) in river water by sampling 15 river sites in the Schwarzbach watershed (about 400 km(2)) from November 2008 to February 2010. Additionally, wastewater samples from three municipal wastewater treatment plants (WWTPs) in Germany were analyzed. BT was detected in all wastewater influent and effluent samples as well as in all river water samples collected downstream of wastewater discharge. This corroborates the ubiquitous occurrence of BT in the aqueous environment. Concentrations were between 58 and 856 ng L(-1) in the river water. The observed mean concentration at the outlet of the investigated catchment was 109 ng L(-1). With only a few exceptions, temporal and spatial variations of BT concentrations in river water were low. Rather similar BT concentrations over a wide range of river discharge indicate that dilution along the mainstream is negligible and, thus, supports the hypothesis that paved surface runoff during rain events is an important BT source not only for wastewater influent but also for river water. This was supported by detecting the highest BT concentrations at sampling locations close to the dense highway network around the city of Frankfurt. Since BT was also detected in river water collected from locations that were clearly unaffected by wastewater effluent discharge, surface runoff must be considered as a diffuse source of BT in river water.

Quantitative high-resolution mapping of phenanthrene sorption to black carbon particles.

Sorption of hydrophobic organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) to black carbon (BC) particles has been the focus of numerous studies. Conclusions on sorption mechanisms of PAH on BC were mostly derived from studies of sorption isotherms and sorption kinetics, which are based on batch experiments. However, mechanistic modeling approaches consider processes at the subparticle scale, some including transport within the pore-space or different spatial pore-domains. Direct evidence based on analytical techniques operating at the submicrometer scale for the location of sorption sites and the adsorbed species is lacking. In this work, we identified, quantified, and mapped the sorption of PAHs on different BC particles (activated carbon, charcoal and diesel soot) on a 25-100 nm scale using scanning transmission X-ray microscopy (STXM). In addition, we visualized the pore structure of the particles by transmission electron microscopy (TEM) on the 1-10 nm-scale. The combination of the chemical information from STXM with the physical information from TEM revealed that phenanthrene accumulates in the interconnected pore-system along primary "cracks" in the particles, confirming an adsorption mechanism.

Atmospheric deposition, retention, and stream export of dioxins and PCBs in a pristine boreal catchment.

The mass-balance between diffuse atmospheric deposition of organic pollutants, amount of pollutants retained by the terrestrial environment, and levels of pollutants released to surface stream waters was studied in a pristine northern boreal catchment. This was done by comparing the input of atmospheric deposition of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs with the amounts exported to surface waters. Two types of deposition samplers were used, equipped with a glass fibre thimble and an Amberlite sampler respectively. The measured fluxes showed clear seasonality, with most of the input and export occurring during winter and spring flood, respectively. The mass balance calculations indicates that the boreal landscape is an effective sink for PCDD/Fs and PCBs, as 96.0-99.9 % of received bulk deposition was retained, suggesting that organic pollutants will continue to impact stream water in the region for an extended period of time.

Transport of polycyclic aromatic hydrocarbons in highly vulnerable karst systems.

Fluxes of polycyclic aromatic hydrocarbons (PAHs) were investigated along the route of transport in a south German karst system. Atmospheric deposition, seepage water in caves and spring water at the outlet of the catchment were monitored continuously over 1.5 years allowing the establishment of an input/output mass balance at the catchment scale. The results reveal that, even in the highly vulnerable karst catchment, PAHs are effectively retained in the soils. Only during high discharge events, such as snowmelt in spring, increasing PAH concentrations at the outlet of the catchment indicates a mobilization of the pollutants. These events are typically correlated with increasing particle concentrations. Based on our results, we conclude that particle-facilitated transport is the dominating cause of PAH mobilization. In summary, PAHs accumulate over time in soils and only occasionally high discharge events cause a short concentration pulse to be flushed through the karst system.

Field calibration of polyurethane foam disk passive air samplers for PBDEs.

A field study was performed to derive uptake rates of airborne polybrominated diphenyl ethers (PBDEs) to polyurethane foam (PUF) disk passive air samplers (PAS) and to investigate the influence of deployment location and device design. Data are presented on the gas-particle partitioning of PBDEs, since atmospheric phase distribution was considered to be a variable which could affect sampler performance. Uptake rates for these compounds were similar to those derived previously for other classes of persistent organic pollutants (POPs) (approximately 2-6 m(3)/day), with rates higher for the higher brominated species. Whilst other compound classes (e.g. polychlorinated biphenyls) are predominantly present in the air in the gas phase, heavier PBDEs have an association with particulates in the atmosphere at ambient temperatures. In this study, the PUF disk PAS therefore sampled PBDEs present in the gas phase and on fine aerosols with a similar sampling efficiency to those which are predominantly gas phase compounds. Compounds which are exclusively on particles are sampled less efficiently. A comparison of the three most commonly used PUF deployment configurations, used by different research groups, indicated little difference in uptake rates. The ranges of derived air concentrations for BDE-47, -99, and -183 between three sampler designs were 7.5-9.8, 7.4-12.4, and 4.7-6.6 pg/m(3), respectively. This suggests the robustness of this sampler in comparisons between regional and global campaigns where these three designs are employed.

Sorption of alkylphenols on Ebro River sediments: comparing isotherms with field observations in river water and sediments.

This study reports sorption isotherms of the endocrine disruptors nonylphenol (NP) and octylphenol (OP) in three sediment samples from the Ebro River basin (NE Spain), with organic carbon fractions (f(OC)) ranging from 0.0035 to 0.082 g(OC)g(-1). All isotherms were fitted to the Freundlich model with slightly nonlinear exponents ranging from 0.80 to 0.94. The solubility of the compounds as well as the organic carbon (OC) content had the strongest influences on the sorption behavior of these compounds. Comparison of the laboratory-spiked samples with the native contamination of NP of 45 water and concurrent sediment samples resulted in reasonable matches between both data sets, even though the lowest concentrations in the field were not completely reached in laboratory tests. This good agreement indicates that sorption laboratory data can be extrapolated to environmental levels and therefore the distribution of nonylphenol between sediments and water can be predicted with a precision of one order of magnitude. Furthermore, laboratory experiments with simultaneous loading of NP and OP revealed negligible competition for sorption sites at low concentrations.

Field calibration of polyurethane foam (PUF) disk passive air samplers for PCBs and OC pesticides.

Different passive air sampler (PAS) strategies have been developed for sampling in remote areas and for cost-effective simultaneous spatial mapping of POPs (persistent organic pollutants) over differing geographical scales. The polyurethane foam (PUF) disk-based PAS is probably the most widely used. In a PUF-based PAS, the PUF disk is generally mounted inside two stainless steel bowls to buffer the air flow to the disk and to shield it from precipitation and light. The field study described in this manuscript was conducted to: compare performance of 3 different designs of sampler; to further calibrate the sampler against the conventional active sampler; to derive more information on field-based uptake rates and equilibrium times of the samplers. Samplers were also deployed at different locations across the field site, and at different heights up a meteorological tower, to investigate the possible influence of sampler location. Samplers deployed <5m above ground, and not directly sheltered from the wind gave similar uptake rates. Small differences in dimensions between the 3 designs of passive sampler chamber had no discernable effect on accumulation rates, allowing comparison with previously published data.

Validation of a passive atmospheric deposition sampler for polybrominated diphenyl ethers.

An atmospheric deposition sampler was validated with respect to polybrominated diphenyl ethers (PBDEs), a compound group that is widely used as flame retardants in many types of consumer products. The deposition sampler consists of an adsorption cartridge that is connected to a glass funnel. Extraction tests with spiked cartridges using soxhlet extraction with acetone revealed recoveries of >80% for all of the investigated PBDEs. Once adsorbed, PBDEs are stable, as proven by extractions of spiked cartridges that were stored outdoors and collected after different periods of time, up to 84 days. High recoveries indicate that degradation of adsorbed PBDEs does not play a role under realistic field conditions. Bulk deposition rates of PBDEs were determined in a field test with 3 replicates, and a possible breakthrough of target compounds was assessed in the field using a second adsorption cartridge in series. No breakthrough of target compounds could be observed within a sampling period of 61 days, and a bulk deposition rate of approximately 1 ng m(-2) day(-1) for the sum of all analysed PBDEs was measured. The highest deposition rates were measured for octa-brominated congeners, followed by BDEs 99, 183, 153, and 47. Overall, the sampler was successfully validated regarding the atmospheric deposition of PBDEs.

Accumulation of polycyclic aromatic hydrocarbons in rural soils based on mass balances at the catchment scale.

Polycyclic aromatic hydrocarbons (PAHs) are hydrophobic organic pollutants that are ubiquitously distributed in the environment at relatively high concentrations. In our study we investigated the long-term fate of atmospheric PAHs in soils of rural areas, resulting from diffuse pollution based on mass balances at the catchment scale. By determining PAHs in several environmental compartments, estimates of soil storages and water fluxes were made and compared with atmospheric deposition. The results indicate that more than 90% of the incoming PAHs remain in the catchments and accumulate in the topsoils. Furthermore, revolatilization of PAHs from soils and degradation in the soils is very limited, resulting in ongoing accumulation in topsoils, in particular for low-volatile PAHs. Combustion-derived carbonaceous particles were detected in atmospheric deposition as well as in the soil samples. Since these particles are very strong adsorbents, they are suspected to play a key role in the environmental fate of the diffuse distributed PAHs.