Direct and Air-Mediated Transfer of Labeled SVOCs from Indoor Sources to Dust.

Two small-scale field studies were conducted to investigate the transfer of substances from products into dust due to direct and air-mediated transfer. The project focused on semivolatile organic compounds (SVOCs), which are frequently found in and re-emitted from dust. For the field studies, four artificial products containing deuterium-labeled SVOCs (eight phthalates and adipates) were installed in residential indoor environments. Two plastic products were installed vertically to investigate substance transfer due to evaporation into air. One plastic product and a carpet were installed horizontally to investigate the direct transfer from source to dust. A pyrethroid was intentionally released by spraying a commercial spray. Dust samples were collected from the floor, elevated surfaces in the room and the surfaces of the horizontally installed products. We observed that the dust concentrations of substances exclusively transferred via air were similar at different collection sites, but the concentrations of chemicals present in horizontal products were up to 3 orders of magnitude higher in dust deposited on the source. We conclude that direct transfer from source into dust substantially increases the final SVOC concentration in dust in contact with the source, regardless of the vapor pressure of investigated SVOCs, and may lead to larger human exposure.

Spatial Distribution of Atmospheric PCBs in Zurich, Switzerland: Do Joint Sealants Still Matter?

Passive air samplers were deployed at 23 sites across the city of Zurich, Switzerland to investigate the spatial distribution of polychlorinated biphenyls (PCBs) in air. Concentrations of the six indicator PCBs (iPCBs) in air ranged from 54 to 3160 pg·m(-3) in the two sampling campaigns (spring 2011 and spring 2013). Measurements at two sampling sites were significantly higher than the median in both years, because of the proximity to primary PCB sources. Concentrations at most other stations were in a narrow range, suggesting that atmospheric PCB concentrations in Zurich are mainly caused by a high number of rather small sources. A correlation of iPCB concentrations in air with the number of buildings constructed between 1955 and 1975 in the surrounding areas of the sampling sites was observed. This demonstrates that PCB-containing building materials, such as joint sealants, influence PCB levels in urban air. Additionally, atmospheric iPCB concentrations were measured in the surrounding of a housing complex with PCB-contaminated joint sealants. Using a Gaussian diffusion model, annual iPCB emissions of 110-190 g were calculated for this housing complex. This appreciable amount released by a single building points out that more efforts are required to further eliminate remaining PCB stocks.

Tracking SVOCs' Transfer from Products to Indoor Air and Settled Dust with Deuterium-Labeled Substances.

Semivolatile organic compounds (SVOCs) can be released from products and distributed in the indoor environment, including air and dust. However, the mechanisms and the extent of substance transfer into air and dust are not well understood. Therefore, in a small-scale field study the transfer of nine SVOCs was investigated: Four artificial consumer products were doped with eight deuterium-labeled plasticizers (phthalates and adipates) and installed in five homes to investigate the emission processes of evaporation, abrasion, and direct transfer. Intentional release was studied with a commercial spray containing a pyrethroid. During the 12 week study, indoor air and settled dust samples were collected and analyzed. On the basis of our measurement results, we conclude that the octanol-air partitioning coefficient Koa is a major determinant for the substance transfer into either air or dust: A high Koa implies that the substance is more likely to be found in dust than in air. The emission process also plays a role: For spraying, we found higher dust and air concentrations than for evaporation. In contrast, apartment parameters like air exchange rate or temperature had just a minor influence. Another important mechanistic finding was that although transfer from product to dust currently is postulated to be mostly mediated by air, direct transport from product to dust on the product surface was also observed.

Short-Chain Chlorinated Paraffins in Zurich, Switzerland--Atmospheric Concentrations and Emissions.

Short-chain chlorinated paraffins (SCCPs) are of concern due to their potential for adverse health effects, bioaccumulation, persistence, and long-range transport. Data on concentrations of SCCPs in urban areas and underlying emissions are still scarce. In this study, we investigated the levels and spatial distribution of SCCPs in air, based on two separate, spatially resolved sampling campaigns in the city of Zurich, Switzerland. SCCP concentrations in air ranged from 1.8 to 17 ng·m(-3) (spring 2011) and 1.1 to 42 ng·m(-3) (spring 2013) with medians of 4.3 and 2.7 ng·m(-3), respectively. Both data sets show that atmospheric SCCP levels in Zurich can vary substantially and may be influenced by a number of localized sources within this urban area. Additionally, continuous measurements of atmospheric concentrations performed at one representative sampling site in the city center from 2011 to 2013 showed strong seasonal variations with high SCCP concentrations in summer and lower levels in winter. A long-term dynamic multimedia environmental fate model was parametrized to simulate the seasonal trends of SCCP concentrations in air and to back-calculate urban emissions. Resulting annual SCCP emissions in the city of Zurich accounted for 218-321 kg, which indicates that large SCCP stocks are present in urban areas of industrialized countries.

Emissions of polychlorinated biphenyls in Switzerland: a combination of long-term measurements and modeling.

Ambient air concentrations of polychlorinated biphenyls (PCBs) in Zurich, Switzerland, are reported for the years 2011-2013. These measurements reveal a distinct seasonal trend with PCB concentrations in air during the summer that were three to five times higher than in the winter. We used a long-term dynamic multimedia model to analyze the seasonal trend and to back-calculate urban emissions of PCBs. In contrast to previous short-term studies that considered time periods of several days to months to extrapolate annual emissions, the use of long-term field data and the corresponding model reduces the uncertainty in these extrapolations. Comparison with measured PCB concentrations in air shows that our model is able to reproduce seasonal trends of the six indicator PCBs (iPCBs). The good agreement of the model results with measurements over a time period of three years provides confidence in model outputs and allows us to estimate the total annual PCB emissions of Zurich (86 µg capita(-1) d(-1)). The resulting summer emissions are nine times higher than emissions during winter. Interestingly, this factor corresponds to the expected increase in PCB volatilization due to the effect of temperature on vapor pressure. This finding implies that PCBs in Zurich are probably released mainly by volatilization from sources that are directly exposed to ambient air temperature (i.e., outdoor sources). The derived emissions are in accordance with previous studies performed at the same location and are also in agreement with an existing emission inventory.

Emissions of polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans during 2010 and 2011 in Zurich, Switzerland.

Persistent organic pollutants (POPs) are ubiquitous contaminants of environmental and human health relevance, but their emissions into the environment are still poorly known. In this study, concentrations of selected POPs were measured in ambient air in Zurich, Switzerland, and interpreted with a multimedia mass balance model. The aim of the combination of measurements and modeling was to back-calculate atmospheric emission rates of POPs. Measurements were performed in summer 2010 and winter 2011 and target analytes included polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Estimated emissions were higher in summer than in winter. Emission estimates for Zurich can be extrapolated to annual averages for Switzerland of 312 kg·a(-1) (39 mg·capita(-1)·a(-1)), 53 kg·a(-1) (7 mg·capita(-1)·a(-1)), and 3 kg·a(-1) (0.4 mg·capita(-1)·a(-1), 94 g WHO98-TEQ·a(-1), 65 g I-TEQ·a(-1)) for the six indicator PCBs (iPCBs), the twelve coplanar dioxin-like PCBs (dlPCBs), and the 17 2,3,7,8-chlorosubstituted PCDD/Fs, respectively. The emission rates of iPCBs are in agreement with existing emission inventories, whereas for PCDD/Fs the emissions are five times higher than the estimates from the Swiss national emission inventory. Emissions of dlPCBs in Switzerland are presented here for the first time. Our study also provides the first seasonally resolved emission rates of POPs, which were determined with our combined measurement and modeling approach. These findings highlight the relevance of ongoing sources of POPs, even decades after regulations aiming to reduce or eliminate sources were established.

Co-release of hexabromocyclododecane (HBCD) and Nano- and microparticles from thermal cutting of polystyrene foams.

Polystyrene foam is a very important insulation material, and hexabromocyclododecane (HBCD) is frequently used as its flame retardant. HBCD is persistent, bioaccumulative, and toxic, and therefore workplace exposure and environmental emission should be avoided. In this study, we investigated the co-release of HBCD and aerosol particles during the thermal cutting of expanded polystyrene foam (EPS) and extruded polystyrene foam (XPS). The generated particles were simultaneously measured by a fast mobility particle sizer (FMPS) and collected by a cascade impactor (NanoMoudi). In the breathing zone of a cutting worker, the number concentration of aerosol particles was above 1 × 10(12) particles m(-3), and the air concentration of HBCD was more than 50 µg m(-3). Most of the released HBCD was partitioned into particles with an aerodynamic diameter at the nanometer scale. The average concentrations of HBCD in these submicrometer particles generated from the thermal cutting of EPS and XPS were 13 times and 15 times higher than the concentrations in raw foams, respectively. An occupational exposure assessment indicated that more than 60% of HBCD and 70% of particles deposited in the lung of cutting worker would be allocated to the alveolar region. The potential subchronic (or chronic) toxicity jointly caused by the particles and HBCD calls for future studies.

Quantifying diffuse and point inputs of perfluoroalkyl acids in a nonindustrial river catchment.

Recently, the role of diffuse inputs of perfluoroalkyl acids (PFAAs) into surface waters has been investigated. It has been observed that river loads increased during rain and that street runoff contained considerable loads of PFAAs. This study aims at quantifying these diffuse inputs and identifying the initial sources in a small nonindustrial river catchment. The river was sampled in three distinct subcatchments (rural, urban, and wastewater treatment plant) at high temporal resolution during two rain events and samples were analyzed for perfluorocarboxylates and perfluorosulfonates. Additionally, rain, stormwater runoff, wastewater effluent, and drinking water were sampled. PFAA concentrations in river water were all low (e.g., < 10 ng/L for perfluorooctanoate, PFOA), but increased during rainfall. PFAA concentrations and water discharge data were integrated into a mass balance assessment that shows that 30-60% of PFAA loads can be attributed to diffuse inputs. Rain contributed 10-50% of the overall loads, mobilization of dry deposition and outdoor release of PFAA from products with 20-60%. We estimated that within a year 2.5-5 g of PFOA originating from rain and surface runoff are emitted into this small catchment (6 km(2), 12,500 persons).

In vitro estrogenicity of ambient particulate matter: contribution of hydroxylated polycyclic aromatic hydrocarbons.

Atmospheric particulate matter (PM1) was collected at an urban and a rural site in Switzerland during a hibernal high air pollution episode and was investigated for estrogenicity using an estrogen-sensitive reporter gene assay (ER-CALUX). All samples that were tested induced estrogen receptor-mediated gene expression in T47D human breast adenocarcinoma cells. Observed estrogenic activities corresponded to 17beta-estradiol (E2) CALUX equivalent concentrations ranging from 2 to 23 ng E2-CEQ per gram of PM1 (particulate matter of < or = 1 microm aerodynamic diameter) and from 0.07 to 1.25 pg E2-CEQ per m(3) of sampled air. There was a strong correlation between the PM1 estrogenicity of the urban and rural sites (r = 0.92). Five hydroxylated polycyclic aromatic hydrocarbons (hydroxy-PAHs), which show structural similarities to E2, were assessed for their estrogenic activity. The following order of estrogenic potency was found: 2-hydroxychrysene > 2-hydroxyphenanthrene > 1-hydroxypyrene > 2-hydroxynaphthalene > 1-hydroxynaphthalene. Three of these hydroxy-PAHs, namely 2-hydroxyphenanthrene, 2-hydroxynaphthalene and 1-hydroxynaphthalene, were detected in all PM1 extracts. However, they contributed only 0.01-0.2% to the overall estrogenic activity. Hence, mainly other estrogenic compounds not yet identified by chemical analysis must be responsible for the observed activity. The temporal trend of PM1 estrogenicity at the urban and rural site, respectively, was compared with the time course of several air pollutants (NO2, NO, SO2, O3, CO) and meteorological parameters (temperature, humidity, air pressure, solar irradiation, wind velocity). However, specific emission sources and formation processes of atmospheric xenoestrogens could not be elucidated. This study showed that ambient particulate matter contains compounds that are able to interact with estrogen receptors in vitro and potentially also interfere with estrogen-regulated pathways in vivo.

Catalytic diesel particulate filters reduce the in vitro estrogenic activity of diesel exhaust.

An in vitro reporter gene assay based on human breast cancer T47D cells (ER-CALUX) was applied to examine the ability of diesel exhaust to induce or inhibit estrogen receptor (ER)-mediated gene expression. Exhaust from a heavy-duty diesel engine was either treated by iron- or copper/iron-catalyzed diesel particulate filters (DPFs) or studied as unfiltered exhaust. Collected samples included particle-bound and semivolatile constituents of diesel exhaust. Our findings show that all of the samples contained compounds that were able to induce ER-mediated gene expression as well as compounds that suppressed the activity of the endogenous hormone 17beta-estradiol (E2). Estrogenic activity prevailed over antiestrogenic activity. We found an overall ER-mediated activity of 1.63 +/- 0.31 ng E2 CALUX equivalents (E2-CEQs) per m(3) of unfiltered exhaust. In filtered exhaust, we measured 0.74 +/- 0.07 (iron-catalyzed DPF) and 0.55 +/- 0.09 ng E2-CEQ m(-3) (copper/iron-catalyzed DPF), corresponding to reductions in estrogenic activity of 55 and 66%, respectively. Our study demonstrates that both catalytic DPFs lowered the ER-mediated endocrine-disrupting potential of diesel exhaust.

Solid-state conformations and absolute configurations of (+) and (-) alpha-, beta-, and gamma-hexabromocyclododecanes (HBCDs).

Hexabromocyclododecanes (HBCDs) are high production volume chemicals used as flame retardants for plastics and textiles. They are currently produced in quantities exceeding 20,000 t/y. Despite this fact, the correct stereochemistry of most HBCDs is still not known. Six stereocenters are formed during bromination of cyclododecatrienes, resulting in mixtures of different stereoisomers. Considering all elements of symmetry, 16 different stereoisomers including six pairs of enantiomers as well as 4 meso forms are possible theoretically. Recently, we isolated 8 of the 16 possible stereoisomers from a technical HBCD mixture and assigned their relative configurations. Herein, we report on the isolation of 6 enantiomerically pure alpha-, beta-, and gamma-HBCDs, obtained from preparative chiral-phase liquid chromatography, and we present their absolute configurations, which were determined from X-ray diffraction analysis. The absolute configuration of (-) alpha-HBCD was found to be (1R,2R,5S,6R,9R,10S), while the one of (+) beta-HBCD is assigned to (1S,2S,5S,6R,9S,10R), whereas the one of (-) gamma-HBCD corresponds to (1S,2S,5S,6R,9R,10S). The given structural information allows the unambiguous identification of the six most important HBCD stereoisomers, which typically account for more than 95% of technical HBCDs. In addition, we compared the solid-state conformations of racemic and enantiomerically pure alpha-, beta-, and gamma-HBCDs. In all cases, vicinal dibromides adopted a synclinal (sc) conformation with torsion angles of 69+/-6 degrees. A unique structural motive was common to all examined HBCD solid-state conformations. This conserved structure was described as an extended triple turn consisting of an arrangement of three pairs of synclinal and two antiperiplanar torsion angles.

The historical record of PCB and PCDD/F deposition at Greifensee, a lake of the Swiss plateau, between 1848 and 1999.

Dated sediment cores provide an excellent way to investigate the historical input of persistent organic pollutants into the environment and to identify possible sources of pollution. The vertical distribution of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/F) and polychlorinated biphenyls (PCB) was investigated in a sediment core from Greifensee to elucidate the historical trends of PCDD/F and PCB inputs between 1848 and 1999. Concentrations of PCB and PCDD/F increased by more than one order of magnitude between 1930 and 1960. PCB and PCDD/F concentrations were 5700 ng/kg dry weight (dw) and 160 ng/kg dw, respectively, in sediments originating from the late 1930s and reached a maximum of 130,000 ng/kg dw and 2400 ng/kg dw, respectively, in the early 1960s. From 1960 on, concentrations decreased to the 1930s level by the mid 1980s. A remarkable shift in the PCDD/F pattern was observed after the early 1940s. Before 1940, the PCDD/F pattern was PCDF dominated (ratio of PCDD to PCDF=0.41+/-0.11), while the PCDD started to be the major species after the early 1940s (ratio of PCDD to PCDF=1.46+/-0.38). The temporal trends of PCB and PCDD/F correlate surprisingly well with each other. This might be due to the coincidence of two factors. The introduction of PCB on the market in the 1930s resulted in emissions due to the widespread use of these industrial chemicals. In the same time period, waste incineration became an increasingly popular way to get rid of garbage, boosting the PCDD/F emissions significantly. The rapid decline of PCDD/F and PCB concentrations in the sediment starting in the early 1960s reflects the result of better emission control techniques in thermal processes and the improvement of waste water treatment in the catchment of Greifensee.

Isocyanate emissions from pyrolysis of mattresses containing polyurethane foam.

This study examined the emissions of powerful asthmatic agents called isocyanates from small-scale pyrolysis experiments of two common foams employed in mattress production such as flexible polyurethane foam (FPUF) and viscoelastic memory foam (VMF). A nitrogen atmosphere and five different temperatures, 300, 350, 400, 450 and 850 °C, were selected to carry out the experiments in order to evaluate the worst possible conditions for thermal degradation. A similar trend for both materials was found. At lower temperatures, diisocyanates were the most important products whereas at 850 °C monoisocyanates, and mainly isocyanic acid released mainly from the thermal cracking of diisocyanates evolved directly from the polymer chains. The total yields of isocyanates were in the range of 1.43-11.95 mg/m3 for FPUF at 300-850 °C and 0.05-6.13 mg/m3 for VMF, 300-850 °C. This difference could be a consequence of the lower amount of isocyanates employed in the VMF production which was confirmed by the nitrogen content of the foams, 5.95% FPUF vs. 3.34% in VMF. Additionally, a qualitative search for so far unknown isocyanates was performed in samples from the pyrolysis of FPUF at 300, 400 and 850 °C. It was confirmed that six different aminoisocyanates at 300 °C were evolved, whereas at 400 and 850 °C only five of them were detected. The general trend observed was a decrease of the aminoisocyanate levels with increasing pyrolysis temperature.

Anaerobic degradation of brominated flame retardants in sewage sludge.

Tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and decabromodiphenyl ether (DecaBDE) are high production volume chemicals used as flame retardants in plastics for products such as electronic equipment, insulation panels, and textiles. The environmental safety of brominated flame retardants, especially their persistence, bioaccumulation, and toxicity is a controversial topic. Here, we studied and compared the degradation of TBBPA, HBCD, and DecaBDE under anaerobic conditions in digested sewage sludge. The half-lives of TBBPA and a technical HBCD mixture were 0.59 and 0.66 d, respectively. The fact that (+/-)-alpha-HBCD exhibited an almost doubled half-life compared to (+/-)-beta-HBCD and (+/-)-gamma-HBCD is an important finding with respect to the discussion on the persistence of individual HBCD stereoisomers and the recent reports on strong relative enrichment of alpha-HBCD in biota. We found no statistically significant enantioselective degradation of alpha-, beta-, or gamma-HBCD. Half-lives of TBBPA and a technical HBCD mixture were not dependent on the presence of additional nutrients or primers. Concentrations of TBBPA and a technical HBCD mixture decreased also in sterile control samples, however, at a rate that was more than a factor of 50 smaller than in incubations under non-sterile conditions. Compared to TBBPA and a technical HBCD mixture, DecaBDE exhibited a much longer half-life of 7 x 10(2)d in the same system. Pseudo-first-order degradation rate constants decreased according to the following sequence: TBBPA congruent with(+/-)-gamma-HBCD congruent with(+/-)-beta-HBCD>(+/-)-alpha-HBCD>>DecaBDE. Preliminary investigations suggest that degradation of TBBPA, HBCD, and DecaBDE occurs in full-scale anaerobic digesters, as well.

Structure elucidation of hexabromocyclododecanes--a class of compounds with a complex stereochemistry.

Hexabromocyclododecanes (HBCDs) are high production volume chemicals (16700 t worldwide in 2001) used as flame-retardants for plastics and textiles. HBCDs exhibit typical properties of persistent organic pollutants (POPs). They are highly lipophilic and accumulate in biota. Increasing environmental concentrations of HBCDs, mostly reported as sum values, have been observed. As such, HBCDs have to be considered as potential emerging POPs, but their occurrence and environmental fate have not yet been addressed at the level of individual HBCD stereoisomers. Considering the six stereogenic centers of HBCDs, 16 stereoisomers, six diastereomeric pairs of enantiomers as well as four meso forms, can be deduced. Herein, we report spectroscopic and chromatographic data for eight out of 16 possible HBCD stereoisomers, which were isolated from a technical product. Six stereoisomers were identified as three pairs of enantiomers ((+/-) alpha-, beta-, and gamma-HBCDs), differing in optical rotation and chromatographic retention on a chiral phase. The crystal structures of these pairs of enantiomers were determined. Another two of these eight HBCD stereoisomers, not yet described in the literature, showed no optical rotation and are tentatively assigned as meso forms (delta- and epsilon-HBCD). The given spectroscopic and chromatographic information allows the unambiguous identification of eight HBCD stereoisomers and the occurrence, fate, and toxicology of these individual stereoisomers can now be studied.

A N-Nitrosodimethylamine (NDMA) precursor analysis for chlorination of water and wastewater.

N-nitrosodimethylamine (NDMA) is a potent carcinogen formed during chloramination of water and wastewater treatment plant effluents. A procedure is described for quantifying the concentration of the organic precursors of NDMA that could be formed during chlorination of wastewaters and natural waters. The method involves applying a high dose of monochloramine to a pH-buffered sample followed by a 10-day contact period, during which the monochloramine decays at a rate unrelated to the composition of the sample. Analyses of samples of municipal wastewater effluents and surface waters indicate that the method provides a robust and reproducible measurement of NDMA precursors over a wide range of conditions. A sensitive GC/CI/MS/MS analytical procedure for dimethylamine also is described and used to demonstrate that NDMA formation during chlorination of wastewater and natural waters cannot be explained by dimethylamine concentrations alone.

Polybrominated diphenyl ethers in whitefish from Swiss lakes and farmed rainbow trout.

A method for trace analysis of polybrominated diphenyl ethers (PBDE) in fish based on gas chromatography/electron ionization high resolution mass spectrometry (GC/EI-HRMS) was developed, and levels of PBDE were determined in whitefish (Coregonus sp.) from eight Swiss lakes and in rainbow trout (Oncorhynchus mykiss) from four Swiss fish farms. PBDE concentrations (sum of PBDE congeners BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) in filet from whitefish between 36 and 165 ng/g lipid weight (lw) were found, corresponding to wet weight (ww) concentrations of 1.6-7.4 ng/gww. PBDE contents in filet from farmed rainbow trout were significantly lower than in wild whitefish (12-24 ng/glw, 0.74-1.3 ng/gww), and the PBDE congener patterns were different for both species (a higher BDE-47 to BDE-99 ratio for farmed rainbow trout compared to wild whitefish was found). Whitefish PBDE levels [ng/glw] correlate better with the surface/volume ratio of the respective lakes (r(2)=0.70) than with other lake properties such as catchment area (size or number of inhabitants) or residence time, suggesting atmospheric deposition as an input pathway for PBDE. Based on an average daily consumption of 20 g whitefish (Switzerland) with a PBDE content of 7.4 ng/gww (highest PBDE concentration detected in this study), a maximum daily intake of 0.15 microg PBDE was estimated (0.026 microg/day for farmed trout). This number corresponds to the lower end of the estimate for the total PBDE intake of the Nordic consumer of 0.2-0.7 microg/day.

Sources of pesticides in surface waters in Switzerland: pesticide load through waste water treatment plants--current situation and reduction potential.

Concentrations of pesticides in Swiss rivers and lakes frequently exceed the Swiss quality goal of 0.1 microg/l for surface waters. In this study, concentrations of various pesticides (e.g., atrazine, diuron, mecoprop) were continuously measured in the effluents of waste water treatment plants and in two rivers during a period of four months. These measurements revealed that in the catchment of Lake Greifensee, farmers who did not perfectly comply with 'good agricultural practice' caused at least 14% of the measured agricultural herbicide load into surface waters. Pesticides, used for additional purposes in urban areas (i.e. protection of materials, conservation, etc.), entered surface waters up to 75% through waste water treatment plants.

Formation of PBDD/F from PBDE in electronic waste in recycling processes and under simulated extruding conditions.

The increasing volumes of waste electrical and electronic equipment (WEEE) in Europe and developing economies demand for efficient disposal solutions. However, WEEE also contains toxic compounds and, therefore, there is a need for recycling technologies for WEEE that creates revenue without causing environmental harm. Among other fast developing economies, South Africa is tempting to make use of recycled plastic. Brominated flame retardants (BFRs) are additives used to protect plastic materials in electrical and electronic equipment (EEE) against ignition. Some BFRs are known persistent organic pollutants (POPs) and some BFRs can be transformed into highly toxic compounds such as polybrominated dibenzofurans and dioxins (PBDD/Fs). In this study, the contents of critical BFRs, i.e. polybrominated diphenyl ethers, and highly toxic PBDD/Fs were measured in WEEE material from Switzerland and South Africa. The formation of PBDD/Fs has been observed in two South African recycling processes and under controlled laboratory conditions. Total PBDE-contents in the South African and Swiss plastic waste varied between 1×10(3) and 7×10(6) µg kg(-1). A few WEEE plastic fractions exceeded the RoHS limit of 1×10(6) µg kg(-1) for PBDEs and thus they could not be used for recycling products without special treatment. The total content of ∑PBDFs was around 1×10(3) µg kg(-1). Such contents in materials do not pose a risk for consumer under normal conditions. Workers at recycling plants might be at risk. The measured formation rates of PBDFs were between 2×10(-5) and 2×10(-4)∑PBDE(-1) min(-1).

Release and environmental impact of silver nanoparticles and conventional organic biocides from coated wooden façades.

This study represents for the first time a comprehensive assessment of functionality and environmental impacts of metallic silver nanoparticles (Ag-NP) compared to conventional organic biocides. Four different transparent, hydrophobic coatings of wooden outdoor façades were tested during one year outdoor weathering. The total silver release from products with Ag-NP was proportional to the overall erosion of the coating. The results indicate that the Ag-NPs are likely transformed to silver complexes, which are considerably less toxic than ionic silver. The protective effect of the silver containing coatings against mold, blue stain and algae was insufficient, even in immaculate and non-weathered conditions. The release of organic biocides from conventional coatings was dependent on the weather conditions, the type of biocide and the use in the base or top coat. The conventional coating showed a good overall performance free from mold, blue stain and algae until the end of the test period.