Including transformation products into the risk assessment for chemicals: the case of nonylphenol ethoxylate usage in Switzerland

A method for applying the risk assessment approach using ratios of predicted environmental concentrations (PECs) and predicted no-effect concentrations (PNECs) to mixtures of parent compounds and their environmental transformation products is presented. Nonylphenol ethoxylates (NPnEOs) and a selection of their most relevant transformation products are investigated as a case study illustrating the method. The PEC values of NPnEO and its transformation products are calculated with a regional multimedia fate model including the transformation kinetics of the NPnEO degradation cascade. PNEC values are derived from a selection of toxicity data on NPnEO and its transformation products. The toxicity of the emerging mixture of NPnEO and its transformation products is then estimated under the assumption of concentration addition (similar mode of action). On this basis, PEC-to-PNEC ratios for the aquatic environment and the sediment are calculated for the individual components of the mixture and the mixture itself. For this purpose, average release rates of NPnEO and its transformation products from Swiss sewage treatment plants were used. While the PEC values of the individual components do not exceed the corresponding PNEC values, the risk quotient of the mixture in water is greater than 1. In sediment, the mixture does not exceed a risk quotient of 1. A combination of sensitivity and scenario analyses is employed to identify the upper and lower bounds of the results.     

Environmental risk assessment of paroxetine

Paroxetine hydrochloride hemihydrate (the active ingredient in Paxil) is a pharmaceutical compound used for the treatment of depression, social anxiety disorder, obsessive compulsive disorder, panic disorder, and generalized anxiety disorder. Paroxetine (PA) is extensively metabolized in humans, with about 97% of the parent compound being excreted as metabolites through the urine and feces of patients. Therefore PA and metabolites have the potential to be discharged into wastewater treatment systems after therapeutic use. PA and its major human metabolite (PM) were investigated using studies designed to describe physical/chemical characteristics and determine their fate and effects in the aquatic environment. A significant portion of the PM entering a wastewater treatment plant would be expected to biodegrade given the higher activated sludge solids concentrations present in a typical wastewater treatment plant. The potential for direct photolysis of PM is also possible based on photolysis results for PA itself. These results provide strong support for expecting that PA and PM residuals will not persist in the aquatic environment after discharge from a wastewater treatment facility. This conclusion is also supported by the results of a USGS monitoring study, where no PM was detected in any of the samples at the 260 ng/L reporting limit. The results presented here also demonstrate the importance of understanding the human metabolism of a pharmaceutical so that the appropriate molecule(s) is used for fate and effects studies. In addition to the PA fate studies, PM was investigated using studies designed to determine potential environmental effects and a predicted no effect level (PNEC). The average measured activated sludge respiration inhibition value (EC50) for PM was 82 mg/L. The measured Microtox EC50 value was 33.0 mg/L, while the Daphnia magna EC50 value was 35.0 mg/L. The PNEC for PM was calculated to be 35.0 microg/L. Fate data were then used in a new watershed-based environmental risk assessment model, PhATE, to predict environmental concentrations (PECs). Comparison of the calculated PECs with the PNEC allows an assessment of potential environmental risk. Within the 1-99% of stream segments in the PhATE model, PEC values ranged from 0.003 to 100 ng/L. The risk assessment PEC/PNEC ratios ranged from approximately 3 x 10(-8) to approximately 3 x 10(-3), indicating a wide margin of safety, since a PEC/PNEC ratio <1 is generally considered to represent a low risk to the environment. In addition, Microtox studies carried out on PM biodegradation byproducts indicated no detectable residual toxicity. Any compounds in the environment as a result of the biodegradation of PM should be innocuous polar byproducts that should not exert any toxic effects.     

抗菌空气过滤材料的制备及其性能研究

利用nano-Ag/nano-TiO2对丙纶熔喷非织造材料进行抗菌功能改性,通过改变等离子体处理时间、nano-Ag/nano-TiO2配比、改性处理时间、改性温度等工艺参数,成功制备出具有抗菌功能的熔喷非织造空气过滤材料,并进行了相关性能测试。结果表明:nano-Ag/nano-TiO2改性的最佳工艺为nano-Ag/nano-TiO2配比36:1,反应温度30℃,改性时间10 min。Nano-Ag/nano-TiO2成功附着在材料表面,且未破坏材料原有纤维结构,过滤性能没有发生大的变化,与未改性的材料一样具有较好的过滤性能。PP熔喷非织造材料经nano-Ag/nano-TiO2改性后,具有明显的抗菌杀菌功能,且有较好的抗菌持久性。     

Environmental exposure and risk assessment of fluoroquinolone antibacterial agents in wastewater and river water of the Glatt Valley Watershed,Switzerland

The mass flows of fluoroquinolone antibacterial agents (FQs) were investigated in the aqueous compartments of the Glatt Valley Watershed, a densely populated region in Switzerland. The major human-use FQs consumed in Switzerland, ciprofloxacin (CIP) and norfloxacin (NOR), were determined in municipal wastewater effluents and in the receiving surface water, the Glatt River. Individual concentrations in raw sewage and in final wastewater effluents ranged from 255 to 568 ng/L and from 36 to 106 ng/L, respectively. In the Glatt River, the FQs were present at concentrations below 19 ng/L. The removal of FQs from the water stream during wastewater treatment was between 79 and 87%. During the studied summer period, FQs in the dissolved fraction were significantly reduced downstream in the Glatt River (15-20 h residence time) (66% for CIP and 48% for NOR). Thus, after wastewater treatment, transport in rivers causes an additional decrease of residual levels of FQs in the aquatic environment. Refined predicted environmental concentrations for the study area compare favorably with the measured environmental concentrations (MEC) obtained in the monitoring study. Total measured FQ concentrations occurring in the examined aquatic compartments of the Glatt Valley Watershed were related to acute ecotoxicity data from the literature. The risk quotients obtained (MEC/PNEC < 1) following the recommendations of the European guidelines or draft documents suggest a low probability for adverse effects of the occurring FQs, either on microbial activity in WWTPs or on algae, daphnia, and fish in surface waters.     

Role of titanium dioxide nanoparticles in the elevated uptake and retention of cadmium and zinc in Daphnia magna

Titanium dioxide nanoparticles (nano-TiO(2)) are now widely applied in consumer products, and the dispersion of nano-TiO(2) may adsorb metals and modify their behavior and bioavailability in the aquatic environment. In the present study, the aqueous uptake, dietary assimilation efficiency (AE), and efflux rate constant (k(e)) of two toxic metals (cadmium-Cd, and zinc-Zn) adsorbed on nano-TiO(2) in a freshwater zooplankton Daphnia magna were quantified. The biokinetics was then compared to daphnids that were exposed only to dissolved metals as controls. The aqueous uptake of Cd and Zn involved an initial rapid uptake and then an apparent saturation, and the uptake of metals was accompanied by an ingestion of nano-TiO(2). The AEs of Cd and Zn adsorbed on nano-TiO(2) were 24.6 ± 2.4-44.5 ± 3.7% and 30.4 ± 3.4-51.8 ± 5.0%, respectively, and decreased with increasing concentrations of nano-TiO(2). Furthermore, the difference between the AEs of Cd and Zn indicated that the desorption of Cd and Zn from nano-TiO(2) may have occurred within the gut of daphnids. With the use of algae as carrier, the AEs of Cd and Zn adsorbed on nano-TiO(2) were significantly higher than those of Cd and Zn directly from nano-TiO(2). The efflux rate constants of Cd and Zn adsorbed on nano-TiO(2) in the zooplankton were significantly lower than those of Cd and Zn not adsorbed on nano-TiO(2). Our study shows that the uptake and retention of toxic metals is enhanced when they are adsorbed on nano-TiO(2), and suggests more attention be paid to the potential influences of nano-TiO(2) on the bioavailability and toxicity of other contaminants.     

Predictive environmental risk assessment of chemical mixtures: a conceptual framework

Environmental risks of chemicals are still often assessed substance-by-substance, neglecting mixture effects. This may result in risk underestimations, as the typical exposure is toward multicomponent chemical "cocktails". We use the two well established mixture toxicity concepts (Concentration Addition (CA) and Independent Action (IA)) for providing a tiered outline for environmental hazard and risk assessments of mixtures, focusing on general industrial chemicals and assuming that the "base set" of data (EC50s for algae, crustaceans, fish) is available. As mixture toxicities higher than predicted by CA are rare findings, we suggest applying CA as a precautious first tier, irrespective of the modes/mechanisms of action of the mixture components. In particular, we prove that summing up PEC/PNEC ratios might serve as a justifiable CA-approximation, in order to estimate in a first tier assessment whether there is a potential risk for an exposed ecosystem if only base-set data are available. This makes optimum use of existing single substance assessments as more demanding mixture investigations are requested only if there are first indications of an environmental risk. Finally we suggest to call for mode-of-action driven analyses only if error estimations indicate the possibility for substantial differences between CA- and IA-based assessments.     

改性纳米TiO2光触媒织物整理剂多功能整理效果研究

根据自制系列改性纳米TiO2光触媒整理剂nano PC所含不同的活性基团,分别采用接技或交联方法,优化纳米TiO2与纤维坚牢结合的化学负载工艺.结果表明:经后整理将纳米TiO2施加到纤维上(改性纳米TiO2光触媒织物整理剂用量1.5%.在改性nano PC中加入一定量的活性基团,可以提高光触媒剂与纤维共价键交联或接枝的能力),织物对甲醛(VOC)降解率>87%,紫外线防护系数(UPF)>35,织物的抗菌性能(金黄色葡萄球菌和大肠杆菌减少率)>85%,经20次洗涤后光催化效果仍无明显变化,且纤维不会产生明显的劣化现象.     

Regulatory FOCUS Surface Water Models Fail to Predict Insecticide Concentrations in the Field

The FOrum for the Co-ordination of pesticide fate models and their USe (FOCUS) exposure models are used to predict the frequency and magnitude of pesticide surface water concentrations within the European regulatory risk assessment. The predictions are based on realistic worst-case assumptions that result in predicted environmental concentrations (PEC). Here, we compared for the first time a larger data set of 122 measured field concentrations (MFC) of agricultural insecticides extracted from 22 field studies to respective PECs by using FOCUS steps 1-4. While FOCUS step 1 and 2 PECs generally overpredicted the MFCs, 23% of step 3 and 31% of step 4 standard PECs were exceeded by surface water MFCs, which questions the protectiveness of the FOCUS exposure assessment. Using realistic input parameters, step 3 simulations underpredicted MFCs in surface water and sediment by 43% and 78%, respectively, which indicate that a higher degree of realism even reduces the protectiveness of model results. The ratios between PEC and MFC in surface water were significantly lower for pyrethroids than for organophosphorus or organochlorine insecticides, which suggests that the FOCUS predictions are less protective for hydrophobic insecticides. In conclusion, the FOCUS modeling approach is not protective for insecticide concentrations in the field.     

Approaches for establishing predicted-no-effect concentrations for population-level ecological risk assessment in the context of chemical substances management

The establishment of rational frameworks for population-level ecological risk assessment (PLERA) in the context of chemical substances management is an important issue. We illustrate two feasible approaches for establishing predicted-no-effect concentrations (PNECs)for PLERA through a case study of 4-nonylphenol (4-NP) using life-cycle toxicity data for medaka (Oryzias latipes). We first quantified the potential impacts of 4-NP on medaka in terms of reduction of population growth rate (i). An age-classified population matrix model (daily time-step) was developed and used to combine life-cycle survivorship and fecundity data obtained from individual-level responses of medaka expDsed to 4-NP into population-level responses defined by the parameter lambda. Thereafter, from the resulting lambdas, two approaches for establishing population-level PNEC values were proposed and examined. We then derived the PNEC values for population-level impacts, based on (a) the threshold concentration, defined as the chemical concentration at which lambda = 1 as a value with a 95% confidence interval, and (b) the no-observed-effect concentration (NOEC) and the maximum-acceptable-toxic concentration (MATC). The results suggest that PNEC values of 4-NP ranging between 0.82 and 2.10 microg/L affect medaka population growth. Although these approaches have their limitations, current knowledge indicates that they are reasonable and practical for evaluating population-level impacts of chemicals, thereby serving as a case study for establishing PNEC values for PLERA in the context of chemical substances management and decision-making.     

Potential release pathways, environmental fate, and ecological risks of carbon nanotubes

Carbon nanotubes (CNTs) are currently incorporated into various consumer products, and numerous new applications and products containing CNTs are expected in the future. The potential for negative effects caused by CNT release into the environment is a prominent concern and numerous research projects have investigated possible environmental release pathways, fate, and toxicity. However, this expanding body of literature has not yet been systematically reviewed. Our objective is to critically review this literature to identify emerging trends as well as persistent knowledge gaps on these topics. Specifically, we examine the release of CNTs from polymeric products, removal in wastewater treatment systems, transport through surface and subsurface media, aggregation behaviors, interactions with soil and sediment particles, potential transformations and degradation, and their potential ecotoxicity in soil, sediment, and aquatic ecosystems. One major limitation in the current literature is quantifying CNT masses in relevant media (polymers, tissues, soils, and sediments). Important new directions include developing mechanistic models for CNT release from composites and understanding CNT transport in more complex and environmentally realistic systems such as heteroaggregation with natural colloids and transport of nanoparticles in a range of soils.     

Predicting methyl tert-butyl ether, tert-butyl formate, and tert-butyl alcohol levels in the environment using the fugacity approach

Through its extensive use as a fuel oxygenate, methyl tert-butyl ether (MTBE) is found nearly ubiquitouslythroughout the environment. To better understand the environmental fate of MTBE, fugacity models are commonly used. However, models developed by the scientific community and by governmental bodies differ in their predictions of relative MTBE concentrations for relevant environmental compartments and of seasonal concentration variations; further, to date they have not considered the formation of transformation products. In this study, the sensitivity of predicted environmental concentrations of MTBE and its two major degradation products, tert-butyl formate (TBF) and tert-butyl alcohol (TBA), to all types of model input parameters is analyzed in a probabilistic sensitivity analysis. This analysis allowed for an assessment of the most influential parameters for predicting soil, water, and air concentrations and thereby provided insight into why previous modeling studies on MTBE differed. Further, the information from the sensitivity analysis was used to parametrize a multispecies transformation model for predicting European concentration levels of MTBE and, for the first time, TBF and TBA. Water and air concentrations of MTBE predicted with the transformation model were in good agreement with measurements of environmental samples. No studies are available on environmental TBF and TBA levels to compare with model predictions; however, the modeling results indicate that, in the water phase, TBA concentrations may reach appreciable levels. One major uncertainty identified regarding the prediction of TBA levels was the fraction of TBA formed from atmospheric MTBE and TBF.     

Occurrence of fumonisins and moniliformin in corn and corn-based food products of U.S. origin

Food-grade corn and corn-based food products intended for human consumption were analyzed for the incidence and levels of fumonisin B1 (FB1), fumonisin B2 (FB2), moniliformin, and Fusarium molds. A total of 100 food-grade commercial corn samples were obtained from two corn processing companies at five different locations in the United States. Seventy-one percent of the samples contained FB1 with concentrations ranging from 43 to 1,642 microg/kg. None of the samples contained FB2. Fifty percent of the samples contained moniliformin with concentrations ranging from 26 to 774 microg/kg. All samples were infected by Fusarium molds, and the infection rates ranged from 8 to 88%. Thirty-four samples of corn-based food products were purchased from supermarkets in Arizona, California, Nebraska, and Ohio. Sixty-five percent of the samples contained FB1, ranging in concentrations from 28 to 2,679 microg/kg. FB2 was detected in 29% of the samples with concentrations ranging from 30 to 797 microg/kg. Sixty-eight percent of the samples contained moniliformin with concentrations ranging from 31 to 858 microg/kg. Sixty-two percent of the samples contained viable Fusarium mold propagules ranging from 9.5 x 10(1) to 5.5 x 10(5)/g. The simultaneous occurrence of FB1 and moniliformin was observed in 34% of corn samples and 53% of corn-based food products. This study has shown co-occurrence of fumonisins and moniliformin in food-grade corn and corn-based foods that indicates a risk of simultaneous exposure of consumers to both toxins.     

纳米TiO2保鲜液对冬枣烂果病及生理品质的影响

纳米材料抗菌防腐作用已在很多领域广泛应用,但由于粒子聚集作用,其抑菌性难以充分发挥。纳米粒子与高分子材料复合可在一定程度上阻止纳米颗粒的聚集,所以将纳米材料复合成高分子复合体应用于农产品防腐保鲜领域将有广泛前景。该研究利用组织分离法从冬枣果实上分离得到了病原真菌,并应用科赫法则验证了其致病性,以羧甲基纤维素钠为基质混合纳米TiO2配成复合保鲜液,对分离得到的致病菌进行了平板抑菌实验,并初步探索了其抑制机理。结果表明,分离得到的冬枣果实致腐菌为半知菌亚门镰孢菌属（Fusarium sp.）真菌,离体实验表明纳米TiO2复合保鲜液对镰孢菌生长有抑制作用,对病原孢子的最低抑菌质量浓度和最低杀菌质量浓度分别为9.77×10-3 g/L和39.06×10-3 g/L,纳米TiO2保鲜液主要通过破坏真菌细胞膜来抑制病原菌的生长;冬枣保鲜研究证实,保鲜液明显降低果实腐烂率并延缓了果实Vc含量的降低。综上,纳米TiO2与CMC-Na复合液可以作为一种有效的抑菌手段应用于采后枣果的镰孢菌防治,为延长冬枣果实保鲜期提供有效的技术支撑。     

Fate of nonylphenol ethoxylates and their metabolites in two Dutch estuaries: evidence of biodegradation in the field

The environmental behavior of nonylphenol ethoxylates (A9PEO) and their metabolites was investigated in field studies in the two Dutch estuaries Western Scheldt and the Rhine estuary. Using liquid chromatography-electrospray mass spectrometry (LC-ES-MS) analysis after solid-phase extraction, A9PEO, nonylphenol (NP), and the carboxylated metabolites (A9PEC) were determined in surface water and sediments. Maximum dissolved concentrations of 2.3, 0.9, and 8.1 microg L(-1), respectively, were found. In sediments, maximum concentrations of 242 and 1080 ng g(-1) for A9PEO and NP were observed. In almost half of the sediment samples, concentrations of A9PEC in sediments were below the detection limit. Occasionally relatively high values were observed, with a maximum of 239 ng g(-1). Metabolites of the carboxy alkylphenoxy ethoxy acetic acids (CAPEC) type could not be detected in any of the sediment or water samples. In the Scheldt estuary, dissolved concentration profiles showed nonconservative behaviorfor all detected compound groups. While A9PEO and NP concentrations strongly decreased along the salinity gradient, this decrease was weaker for the A9PEC metabolites. The increasing concentration ratio of A9PEC/A9PEO clearly illustratesthe important role that aerobic biodegradation plays in the estuarine fate of these compounds. It is concluded that the oxidative hydrolytic degradation pathway is the main degradation route in this nonstratified estuary. At high salinities, where concentrations drop to background levels of around 50 ng L(-1), this ratio decreases to about unity. Simple model calculations show that this can be explained if continuous diffuse discharges (e.g. from the intensive shipping in the estuary) are assumed. For the stratified Rhine estuary the water concentration profiles are less pronounced, possibly due to more complicated and turbulent water flows and point sources from the Rotterdam harbors.     

纳米TiO2改善棉织物抗皱整理强力损失

在棉织物抗皱整理工作液中加入纳米二氧化钛，可以提高免烫织物的强力。探讨了纳米二氧化钛用量对纯棉平纹、斜纹织物抗皱整理效果及织物强力的影响。研究表明，纳米二氧化钛的浓度为0．1g/L时，效果最佳。     

In situ observations of nanoparticle early development kinetics at mineral-water interfaces

The early development of nanoparticles at mineral-water interfaces exerts crucial influences on the sequestration and transport of aqueous toxic species originating from both natural and anthropogenic sources. Homogeneous and heterogeneous nucleation often occur simultaneously, making it difficult to sort out whether toxic species are transported as free species, sorbed on nanoparticle surfaces, or trapped between aggregated nanoparticles. Here, using a newly developed X-ray scattering setup, we show how homogeneous nucleation and growth can be quantitatively separated from heterogeneous processes under aqueous conditions in real-time. Under conditions found in acid-mine-drainage (at pH 3.6 and [Fe(3+)] = 10(-4) M), heterogeneous nucleation of iron oxide nanoparticles on quartz dominated homogeneous nucleation by a factor of 192 (by particle volume). The smallest heterogeneously formed nanoparticles had radii of 1.7 ± 0.5 nm, significantly smaller than the size estimated using classical nucleation theory (CNT). Based on the data, the dominant nucleation and growth mechanisms of iron oxide nanoparticles depending on ionic strength were presented. Our findings have implications for the formation and transport of nanoparticles, and thus toxins, in both environmental and biological systems.     

功能性聚砜酰胺纳米复合材料的研究现状与分析

聚砜酰胺具有良好的耐热性、热稳定性和阻燃性能,但常规聚砜酰胺纤维存在体积比电阻高和抗紫外线性能差等缺陷,导致后续加工困难,限制了其在防护类服装领域的应用.通过对功能性聚砜酰胺纤维制备及改良现状的概括与分析,重点介绍了碳纳米管基本力学和导电性能以及纳米二氧化钛紫外线吸收和屏蔽功能,阐述了碳纳米管和纳米二氧化钛对聚砜酰胺纤...     

屏蔽型纳米TiO2的结构及其整理棉织物的性能

在纳米TiO2颗粒外层包裹有机物和SiO2，经高温烧灼处理，制备了具有独特中空结构的屏蔽型纳米TiO2，其粒径20nm左右，锐钛矿相的含量80％以上。屏蔽型纳米TiO2具有明显的分解甲醛作用；其中空屏蔽结构阻隔了与被整理物之间的直接接触，光催化活性比未改性纳米TiO2有一定程度的降低，经其整理的棉织物的光催化降强也小得多。     

碳纳米管/CeO2静电自组装制备及其抗紫外线性能

织物中纳米粒子的团聚是个亟待解决的问题。以混酸氧化法制备表面带负电荷的羧基化碳纳米管分散体系,与带正电荷的Ce3+进行静电自组装;以NaOH为沉淀剂,经煅烧制得碳纳米管/CeO2复合材料;通过改变碳纳米管与CeO2不同质量比,采用织物涂覆工艺运用于纺织品,研究其抗紫外性能。采用X射线衍射分析(XRD)、透射电子显微镜(TEM)和紫外光分度计对复合材料进行了结构分析和性能测试。结果表明,粒径为4-6 nm的CeO2粒子通过静电自组装均匀分布在碳管表面,包覆层厚度可达12 nm;并发现碳纳米管与CeO2质量比为1:25时,抗紫外性能最佳,其紫外吸收性率比纳米氧化铈高30%。