Environmental Hazard Assessment Research Articles

A European perspective on alternatives to animal testing for environmental hazard identification and risk assessment

Tests with vertebrates are an integral part of environmental hazard identification and risk assessment of chemicals, plant protection products, pharmaceuticals, biocides, feed additives and effluents. These tests raise ethical and economic concerns and are considered as inappropriate for assessing all of the substances and effluents that require regulatory testing. Hence, there is a strong demand for replacement, reduction and refinement strategies and methods. However, until now alternative approaches have only rarely been used in regulatory settings. This review provides an overview on current regulations of chemicals and the requirements for animal tests in environmental hazard and risk assessment. It aims to highlight the potential areas for alternative approaches in environmental hazard identification and risk assessment. Perspectives and limitations of alternative approaches to animal tests using vertebrates in environmental toxicology, i.e. mainly fish and amphibians, are discussed. Free access to existing (proprietary) animal test data, availability of validated alternative methods and a practical implementation of conceptual approaches such as the Adverse Outcome Pathways and Integrated Testing Strategies were identified as major requirements towards the successful development and implementation of alternative approaches. Although this article focusses on European regulations, its considerations and conclusions are of global relevance.

Different transcriptional responses of heat shock protein 20 in the marine diatomDitylum brightwelliiexposed to metals and endocrine-disrupting chemicals

Diatoms are sensitive indicators of water quality, and hence used for environmental hazard assessments; however, their toxicogenomic studies have been insufficiently attempted. In the present study, we determined the cDNA sequence of heat shock protein 20 (Hsp20) gene from the diatom Ditylum brightwellii, and examined the transcriptional responses of the gene after exposing it to environmental stressors such as thermal shock, metals, and endocrine-disrupting chemicals (EDCs). The open reading frame (ORF) of DbHsp20 was 531 bp long, encoding 177 amino acid residues (19.49 kDa) with a conserved C-terminal and α-crystallin domain. The genomic region of DbHsp20 did not contain introns. Phylogeny of eukaryotic Hsp20s showed D. brightwellii was closely related to other diatoms. With regard to the gene expressional profile, real-time PCR results showed that the gene was significantly upregulated (P < 0.001) under thermal stress, with the highest change of 3.2-fold. Metals' (copper and nickel) treatments showed that it was induced after a certain point of treated concentration. On the contrary, EDCs did not display noticeable change on the expression of DbHsp20. These results suggest that the diatom Hsp20 basically responds to thermal stress, but may differentially respond to toxic substances such as metals and organic compounds such as EDCs.

Different transcriptional responses of heat shock protein 70/90 in the marine diatom Ditylum brightwellii exposed to metal compounds and endocrine-disrupting chemicals

Environmental hazard assessments using diatoms have been well documented; however, their molecular toxicology has not been sufficiently studied. In this study, we characterized heat shock protein (HSP) 70/90 of the diatom Ditylum brightwellii (Db) and evaluated their transcriptional profiles in response to various environmental stresses (e.g., thermal shocks and metal and non-metal pollutants). Putative DbHSP70 (658aa, 71.7kDa) and DbHSP90 (707aa, 80.2kDa) proteins had conserved HSP family motifs but different C-terminus motifs, that is, “EEVD” in DbHSP70 and “MEEVD” in DbHSP90. Phylogenetic analyses of both proteins showed that D. brightwellii was well clustered with other diatoms. Real-time PCR analysis showed that thermal stress considerably upregulated DbHSP70 and DbHSP90. As for chemical pollutants, DbHSP70 greatly responded to CuSO4 and NiSO4 exposure, but not CuCl2 or NiCl2. However, DbHSP90 was significantly upregulated by all the metal compounds tested (CuSO4, NiSO4, CuCl2, and NiCl2). Strikingly, the expression of both genes was not induced by the organic pollutants tested, such as endocrine-disrupting chemicals. These data suggest that DbHSP70 and DbHSP90 are differentially involved in the defense response against various environmental stressors. Moreover, metal toxicity may be specifically affected by the conjugated anion in the metal compounds (e.g., SO42- and Cl−).

Zebrafish embryos as an alternative model for screening of drug-induced organ toxicity

Zebrafish have initially emerged as model in developmental biology. The ease of maintenance, high number of offspring, transparency of the eggs and its suitability in mutagenicity screens to unravel developmental pathways contributed to its popularity. Today, it can be considered as one of the best characterised vertebrate models and more than 1,000 labs worldwide use the zebrafish (Strahle et al. 2012). At around 1990 zebrafish were discovered also as a toxicology model (Gorge and Nagel 1990), and the popularity is still increasing (Busch et al. 2011). A major reason for the attractiveness of this small teleost is associated with the suitability of its embryonic life stages. Early life stages are considered to sentinel no or less pain or discomfort when exposed to chemicals. Hence, according to European regulation (EU 2010), they are accepted as alternatives to animal experiments (Embry et al. 2010; Halder et al. 2010). Furthermore, the zebrafish embryo model has the principal capacity of high-throughput analysis and can be used in, for example, screenings for low toxicity of drug candidates. Zebrafish embryos provide an enormous versatility of applications in both environmental and human hazard assessment ranging from acute systemic toxicity (Ali et al. 2011; Lammer et al. 2009; Padilla et al. 2012), chronic toxicity (Volz et al. 2011), teratogenicity (Gustafson et al. 2012; Selderslaghs et al. 2009), neuractivity/neurotoxicity (Kokel et al. 2010; Selderslaghs et al. 2010), and endocrine disruption (Brion et al. 2012; Thienpont et al. 2011) to specific organ toxicities (Berghmans et al. 2008; Parng et al. 2002). As outlined by the paper of Driessen et al. in this issue of Archives in toxicology, hepatotoxicity is one of the major concerns of organ toxicity in drug development. Identification of hepatoxicity as early as possible in the drug development pipeline would reduce the costs associated with development of new medicines. Traditional animal models are time and cost intensive and subject to ethical concerns. Genuine cell-based in vitro methods do not provide the complexity of animal models and may provide only limited predictivity. Therefore, the zebrafish embryo has been proposed also as a better model to identify organ toxicity. As shown by Driessen et al., zebrafish embryos can indeed be used to identify hepatotoxicity. However, it is important to translate the observations appropriately, since histopathological effects or individual gene responses may differ among vertebrates. Identification of key events and conserved mechanisms can be supported by toxicogenomic analysis, and hence, it is not surprising that the number of studies in zebrafish embryos supported or accompanied by toxicogenomic analysis is increasing (e.g. Buttner et al. 2012; Hermsen et al. 2012; Pelayo et al. 2012; Schiller et al. 2012; Yang et al. 2007). Transcriptional profiling of whole embryos is even able to reveal organ-specific profiles—as shown in the Driessen paper in this issue and by various other studies (e.g. Kluver et al. 2011; Yang et al. 2007). With the advent of next generation sequencing (NGS), new perspectives for transcriptome profiling by RNA-sequencing (RNA-seq) are provided also for the zebrafish embryo model (Aanes et al. 2011; Vesterlund et al. 2011). With RNA-seq, novel transcripts from annotated or non-annotated regions not available in predefined probe sets, alternative splicing forms and rare transcripts can be detected. This could be important for the comparative analysis and identification of conserved key toxicity pathways in vertebrates. At present, S. Scholz (&) Department of Bioanalytical Ecotoxicology, UFZ Helmholtz Centre for Environmental Research, Permoserstr. 15, 04318 Leipzig, Germany e-mail: Stefan.Scholz@ufz.de

Composite hydrogeological investigation and characterisation methods applied at a nuclear power plant site in Taiwan

AbstractDrawing from the lessons learnt from the Fukushima nuclear disaster in Japan, the assessment of subsurface environmental hazard around nuclear power plants has emerged as a critical task. Consequently, aiming to better understand the possible environmental impact of radiation leaks into the groundwater, a prescreening programme was initiated in 2011 by the Taiwanese government. As part of this programme, this study conducted various borehole prospecting techniques to identify in situ hydrogeological characteristics at Chin‐Shan Nuclear Power Plant. Borehole electrical log, sonic log and temperature/conductivity log were conducted to explain the regional lithologic conditions and permeability of the formation. In conjunction with this, the interwell tracer and pumping test was carried out to simultaneously determine the hydraulic parameters. In our opinion, the implementation of such in situ end‐to‐end investigations is essential in interpreting in situ fluid and solute transport dynamics prior to programming any numerical scheme for early warning, vulnerability assessment and regular monitoring of a nuclear power plant site.

Long-term seismic performance of RC structures in an aggressive environment: emphasis on bridge piers

Even though accurate structural models have been developed for the performance of corroded structures subjected to monotonic flexure and/or shear, studies on seismic performance that include corrosion damage are scarce. For the lifetime assessment of structures in aggressive environments and earthquake-prone regions, the effects of corrosion on seismic performance need to be taken into consideration. Whereas the seismic demand depends on the results of seismic hazard assessment, the deterioration of seismic capacity depends on the environmental hazard assessment. The analysis of the life-cycle reliability of corroded reinforced concrete (RC) structures under earthquake excitations is the topic of this paper. It includes (a) estimation of the seismic capacity of corroded RC components; (b) seismic and airborne chloride hazard assessment and (c) life-cycle seismic reliability of bridges with corrosion damage. In particular, this paper introduces the visualisation of corrosion process in RC members using X-ray for modelling the spatial variability of rebar corrosion. A novel computational procedure to integrate the probabilistic hazard associated with airborne chlorides into life-cycle seismic reliability of bridge piers is presented.

Prediction of human genes and diseases targeted by xenobiotics using predictive toxicogenomic-derived models (PTDMs)

New technologies for systems-level determinants of human exposure to drugs, industrial chemicals, pesticides, and other environmental agents provide an invaluable opportunity to extend the understanding of human health and potential environmental hazards. We report here the development of a new computational-systems toxicology framework, called predictive toxicogenomics-derived models (PTDMs). PTDMs integrate three networks of chemical-gene interactions (CGIs), chemical-disease associations (CDAs) and gene-disease associations (GDAs) to infer chemical hazard profiles, identify exposure data gaps and to incorporate genes and disease networks into chemical safety evaluations. Three comprehensive networks addressing CGI, CDA and GDA extracted from the comparative toxicogenomics database (CTD) were constructed. The areas under the receiver operating characteristics curve ranged from 0.85 to 0.97 and were yielded using our methodology using a 10-fold cross validation by a simulation carried out 100 times. As the illustrated examples show, we predicted new potential target genes and diseases for bisphenol A and aspirin. The molecular hypothesis and experimental evidence from published literature for these predictions were provided. The results demonstrated that our method has potential applications for chemical profiling in human health exposure and environmental hazard assessment.

AdmetSAR: A Comprehensive Source and Free Tool for Assessment of Chemical ADMET Properties

Absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties play key roles in the discovery/development of drugs, pesticides, food additives, consumer products, and industrial chemicals. This information is especially useful when to conduct environmental and human hazard assessment. The most critical rate limiting step in the chemical safety assessment workflow is the availability of high quality data. This paper describes an ADMET structure-activity relationship database, abbreviated as admetSAR. It is an open source, text and structure searchable, and continually updated database that collects, curates, and manages available ADMET-associated properties data from the published literature. In admetSAR, over 210,000 ADMET annotated data points for more than 96,000 unique compounds with 45 kinds of ADMET-associated properties, proteins, species, or organisms have been carefully curated from a large number of diverse literatures. The database provides a user-friendly interface to query a specific chemical profile, using either CAS registry number, common name, or structure similarity. In addition, the database includes 22 qualitative classification and 5 quantitative regression models with highly predictive accuracy, allowing to estimate ecological/mammalian ADMET properties for novel chemicals. AdmetSAR is accessible free of charge at http://www.admetexp.org.

The Prevention of Falls

Performing a fall-related multifactorial assessment combined with a multifactorial intervention is likely to reduce the rate of falls and risk of falling. For a high risk group, a more comprehensive assessment is required. Multifactoral intervention means the adjusted subset of interventions that target the risk factors that have been identified through a fall risk assessment. Overall, current evidence shows that they reduce the rate of falls in older people living in the community. Exercise programs are effective in reducing the rate of falls. Especially, programs including balance training are more beneficial. Exercise duration needs to be long enough to obtain its benefit. Patients who have fallen should have their medication reviewed and for older individuals, a reduction or withdrawal of the medication should be considered. An 800 IU vitamin D daily supplement is recommended for all older adults at risk of falls. Environmental hazard assessment and modification, managing vision impairment, postural hypertension, heart rate and rhythm abnormalities, foot and footwear problems and the use of assistive devices are also beneficial and recommended.

Exploring QSTR analysis of the toxicity of phenols and thiophenols using machine learning methods

There is an increasing need for the rapid safety assessment of chemicals by both industries and regulatory agencies throughout the world. In silico techniques are practical alternatives in the environmental hazard assessment. In this background, quantitative structure–toxicity relationship (QSTR) analysis has been performed on toxicity of phenols and thiophenols to Photobacterium phosphoreum. The techniques of classification and regression trees (CART) and least squares support vector regressions (LS-SVR) were applied successfully as variable selection and mapping tools, respectively. Four descriptors selected by the CART technique have been used as inputs of the LS-SVR for prediction of toxicities. The best model explains 91.8% leave-one-out predicted variance and 93.0% external predicted variance. The predictive performance of the CART-LS-SVR model was significantly better than the previous reported models based on CoMFA/CoMSIA and stepwise MLR techniques, suggesting that the present methodology may be useful to predict of toxicity, safety and risk assessment of chemicals.

An effective strategy for a whole-cell biosensor based on putative effector interaction site of the regulatory DmpR protein.

Introduction and RationaleThe detection of bioavailable phenol is a very important issue in environmental and human hazard assessment. Despite modest developments recently, there is a stern need for development of novel biosensors with high sensitivity for priority phenol pollutants. DmpR (Dimethyl phenol regulatory protein), an NtrC-like regulatory protein for the phenol degradation of Pseudomonas sp. strain CF600, represents an attractive biosensor regimen. Thus, we sought to design a novel biosensor by modifying the phenol detection capacity of DmpR by using mutagenic PCR.MethodsBinding sites of ‘A’ domain of DmpR were predicted by LIGSITE, and molecular docking was performed by using GOLD to identify the regions where phenol may interact with DmpR. Total five point mutations, one single at position 42 (Phe-to-Leu), two double at 140 (Asp-to-Glu) and 143 (Gln-to-Leu), and two double at L113M (Leu-to- Met) and D116A (Asp-to- Ala) were created in DmpR by site-directed mutagenesis to construct the reporter plasmids pRLuc42R, pRLuc140p143R, and pRLuc113p116R, respectively. Luciferase assays were performed to measure the activity of luc gene in the presence of phenol and its derivatives, while RT-PCR was used to check the expression of luc gene in the presence of phenol.ResultsOnly pRLuc42R and pRLuc113p116R showed positive responses to phenolic effectors. The lowest detectable concentration of phenol was 0.5 µM (0.047 mg/L), 0.1 µM for 2, 4-dimethylphenol and 2-nitrophenol, 10 µM for 2, 4, 6-trichlorophenol and 2-chlorophenol, 100 µM for 2, 4-dichlorophenol, 0.01 µM for 4-nitrophenol, and 1 µM for o-cresol. These concentrations were measured by modified luciferase assay within 3 hrs compared to 6–7 hrs in previous studies. Importantly, increased expression of luciferase gene of pRLuc42R was observed by RT-PCR.ConclusionsThe present study offers an effective strategy to design a quick and sensitive biosensor for phenol by constructing recombinant bacteria having DmpR gene.

Environmental hazard assessment of coal fly ashes using leaching and ecotoxicity tests

The environmental hazard of six coal fly ash samples collected from various coal incineration plants were examined in the present study, using various leaching tests along with physicochemical and ecotoxicological analyses. Physicochemical analyses indicated that the concentration of Ba, Cr, Mo, Se, sulfates and total dissolved solids (TDS) exceeded the threshold values, according to the European Council decision 2003/33/EC for inert, non-hazardous or hazardous waste. The highest sensitivity, among examined organisms, was presented by Daphnia magna and was ascribed to the lowest tolerance of the organism to Cr. The toxic effect profile of the leachates toward Vibrio fischeri revealed that its bioluminescence was significantly altered by the presence of heavy metals in the leachates (such as Cu, Ni and Zn) in low or sub-lethal doses. Although the toxicity of the leachates toward Pseudokirchneriella subcapitata was relatively high, the correlation between the toxicity and heavy metals concentration was rather poor, indicating the significance of the bioavailability of constituents and the importance of toxicity testing. Based on the classification of the samples resulted by physicochemical analyses of the leachates and the results of ecotoxicity tests, Physicochemical and Ecotoxicological indices were also defined, for an overall evaluation of the environmental impact assessment of fly ashes. The suggested indices showed that ecotoxicity tests were in some cases inconsistent with the outcome of waste classification based on physicochemical analyses. Moreover, the examination of leaching protocols and obtained results showed that one stage leaching test (L/S=10L/kg) underestimated the fly ash classification, when compared with the two stage test EN 12457-3 at the cumulative ratio L/S=10L/kg. In addition, the application of availability test NEN 7341 provided useful results about the ecotoxicity wastes. Thus, NEN 7341 is strongly suggested for the implementation of such studies, since the bioavailability of constituents may not be altered by pH adjustment tactics and pH-originated toxicity effects may be avoided.

English

&nbsp; In present study, an extensive health survey of 573 lime kiln workers of Maihar and Jhukehi region of Madhya Pradesh was done for impact assessment of occupational and environmental health hazards&rsquo; exposure on their health behavior. Various physical and physiological disorders of workers were screened with the cooperation of physicians and consultants. Among the observed health anomalies, eye disorders with 39.08% were ranked the highest, followed by respiratory disorders (20.06%), cardiovascular disorders (17.44%), skin disorders (15.70%), and gastrointestinal disorders (7.64%). Health illness was observed to increase with aging and length of hazard exposure. &nbsp; Key words: Lime kilns, respiratory disorder, skin disorder, respiratory disorder, cardiovascular disorder

In Silico Assessment of Chemical Biodegradability

Biodegradation is the principal environmental dissipation process. Due to a lack of comprehensive experimental data, high study cost and time-consuming, in silico approaches for assessing the biodegradable profiles of chemicals are encouraged and is an active current research topic. Here we developed in silico methods to estimate chemical biodegradability in the environment. At first 1440 diverse compounds tested under the Japanese Ministry of International Trade and Industry (MITI) protocol were used. Four different methods, namely support vector machine, k-nearest neighbor, naïve Bayes, and C4.5 decision tree, were used to build the combinatorial classification probability models of ready versus not ready biodegradability using physicochemical descriptors and fingerprints separately. The overall predictive accuracies of the best models were more than 80% for the external test set of 164 diverse compounds. Some privileged substructures were further identified for ready or not ready biodegradable chemicals by combining information gain and substructure fragment analysis. Moreover, 27 new predicted chemicals were selected for experimental assay through the Japanese MITI test protocols, which validated that all 27 compounds were predicted correctly. The predictive accuracies of our models outperform the commonly used software of the EPI Suite. Our study provided critical tools for early assessment of biodegradability of new organic chemicals in environmental hazard assessment.

Assessment of environmental hazards at abandoned mining sites: A case study in Sardinia, Italy

In the last two centuries, several Pb–Zn mines were active in the Rio Mannu basin near Narcao (SW Sardinia, Italy), but are now abandoned. These abandoned mines pose a serious risk to the population and required an assessment of the hazard sources and the contaminant pathways in the area. The characterization plan of the Rio Mannu basin was carried out according to Italian protocols. Specifically, samples of soil, stream sediment, fine-grained ore-processing waste (from washery and flotation processes), surface water and groundwater have been analyzed in order to assess the levels of contamination in each mine area and the risks in the plains surrounding the site. Several potential chemical contaminants were considered both in solid materials and water samples. The Rosas mine was recognized as the most contaminated area in the basin, due to the presence of a large tailing pond, some fine-grained waste piles and two mine adits with concentrations of the toxic elements As, Cd, Cu, Pb, Sb and Zn exceeding Italian regulatory standards. The dispersion of contaminants occurs downstream from the small stream draining the area. In case of heavy rain the runoff into the streamlet transports the contaminated material far into the plain. The results of this study show that the characterization plan is a relatively cheap tool for establishing mitigation actions, prior to the realization of a complete, and usually expensive, remediation project at abandoned mine sites. Urgent recommended actions in the Rio Mannu basin include the treatment of the adit water prior to its discharge into the Rio Barisonis; the construction of drainage barriers on waste piles to reduce runoff and solid transport into the Rio Barisonis; the consolidation of the earthen dam containing the tailing pond of Rosas to avoid the deepening of erosion furrows that may threaten its stability.

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.

Methodology to account for uncertainties and tradeoffs in pharmaceutical environmental hazard assessment

Many pharmaceutical products find their way into receiving waters, giving rise to concerns regarding their environmental impact. A procedure was proposed that enables ranking of the hazard to aquatic species and human health due to such products. In the procedure, hazard assessment is based on five of the pharmaceutical product's individual physico-chemical properties. These properties are aggregated using the weighted Euclidian distance as the utility function. The weights and physico-chemical properties are considered as random variables. Physico-chemical property uncertainty criteria are obtained from a literature review. Weight uncertainty is based on a hazard ranking from a panel of experts, the histogram of which is converted into a continuous probability density function using statistical Kernel smoothing technique. The hazard-ranking procedure was applied to a list of common pharmaceuticals used in Switzerland. The procedure is target-specific. Two rankings were presented: One giving priority to environmental protection and the other to human health. For most substances, the hazard rank depends on the target. For the Swiss case study, the ranking procedure led to the conclusion that the hormones ethinylestradiol and testosterone, along with the antibiotic erythromycin A, should be in all cases included in risk-assessment methodologies, environmental concentration estimates and regular measurement campaigns. The methodology proposed is flexible and can be extrapolated to other substances and groups of experts.

In silico prediction of toxic action mechanisms of phenols for imbalanced data with Random Forest learner

With an increasing need for the rapid and effective safety assessment of compounds in industrial and civil-use products, in silico toxicity exploration techniques provide an economic way for environmental hazard assessment. The previous in silico researches have developed many quantitative structure–activity relationships models to predict toxicity mechanisms for last decade. Most of these methods benefit from data analysis and machine learning techniques, which rely heavily on the characteristics of data sets. For Tetrahymena pyriformis toxicity data sets, there is a great technical challenge—data imbalance. The skewness of data class distribution would greatly deteriorate the prediction performance on rare classes. Most of the previous researches for phenol mechanisms of toxic action prediction did not consider this practical problem. In this work, we dealt with the problem by considering the difference between the two types of misclassifications. Random Forest learner was employed in cost-sensitive learning framework to construct prediction models based on selected molecular descriptors. In computational experiments, both the global and local models obtained appreciable overall prediction accuracies. Particularly, the performance on rare classes was indeed promoted. Moreover, for practical usage of these models, the balance of the two misclassifications can be adjusted by using different cost matrices according to the application goals.

Quantifying dust emissions from desert landforms, eastern Mojave Desert, USA

The measurement of natural dust emissions from desert landforms is crucial in environmental hazard assessment and field checking the accuracy of global dust models. More than 500 individual dust measurements from eight common desert landforms in southern California were collected using the PI-SWERL (Portable In Situ Wind Erosion Lab). The largest emitters of dust are dry washes (13.787 to 0.007 mg m − 2 s − 1 ), dunes, playa margins, distal alluvial fans, and lacustrine beaches. Low emitters include salt-crusted playas (0.692 to 0.002 mg m − 2 s − 1 ), silt–clay-crusted playas, and desert pavements. High emissions are a function of saltating sand that bombards the surface, liberating dust-sized particles for entrainment. Low dust emissions are primarily a function of surface crusting, gravel armoring, and vegetation density. PI-SWERL measurements reveal that emission rates can vary by at least three orders of magnitude, reflecting local variability in soil texture and continuity of surface crusts. Shear-stress partitioning models can be applied to dust data measured by the PI-SWERL to account for large surface roughness features, such as vegetation. The results presented here give an approximation of the contributions to atmospheric dust loading by landforms in the Mojave Desert, and can potentially be used to improve atmospheric dust models.

Environmental and health hazard ranking and assessment of plastic polymers based on chemical composition

Plastics constitute a large material group with a global annual production that has doubled in 15years (245million tonnes in 2008). Plastics are present everywhere in society and the environment, especially the marine environment, where large amounts of plastic waste accumulate. The knowledge of human and environmental hazards and risks from chemicals associated with the diversity of plastic products is very limited. Most chemicals used for producing plastic polymers are derived from non-renewable crude oil, and several are hazardous. These may be released during the production, use and disposal of the plastic product. In this study the environmental and health hazards of chemicals used in 55 thermoplastic and thermosetting polymers were identified and compiled. A hazard ranking model was developed for the hazard classes and categories in the EU classification and labelling (CLP) regulation which is based on the UN Globally Harmonized System. The polymers were ranked based on monomer hazard classifications, and initial assessments were made. The polymers that ranked as most hazardous are made of monomers classified as mutagenic and/or carcinogenic (category 1A or 1B). These belong to the polymer families of polyurethanes, polyacrylonitriles, polyvinyl chloride, epoxy resins, and styrenic copolymers. All have a large global annual production (1–37million tonnes). A considerable number of polymers (31 out of 55) are made of monomers that belong to the two worst of the ranking model's five hazard levels, i.e. levels IV–V. The polymers that are made of level IV monomers and have a large global annual production (1–5million tonnes) are phenol formaldehyde resins, unsaturated polyesters, polycarbonate, polymethyl methacrylate, and urea-formaldehyde resins. This study has identified hazardous substances used in polymer production for which the risks should be evaluated for decisions on the need for risk reduction measures, substitution, or even phase out.