Characterizing export of land-based microplastics to the estuary - Part I: Application of integrated geospatial microplastic transport models to assess tire and road wear particles in the Seine watershed.

Human and ecological exposure to micro- and nanoplastic materials (abbreviated as MP, < 5 mm) occurs in both aquatic and terrestrial environments. Recent reviews prioritize the need for assessments linking spatially distributed MP releases with terrestrial and freshwater transport processes, thereby providing a better understanding of the factors affecting MP distribution to the sea. Tire and road wear particles (TRWP) have an estimated generation rate of 1 kg tread inhabitant-1 year-1 in Europe, but the fate of this MP source in watersheds has not been systematically assessed. An integrated temporally and geospatially resolved watershed-scale MP modeling methodology was applied to TRWP fate and transport in the Seine (France) watershed. The mass balance considers TRWP generation and terrestrial transport to soil, air, and roadways, as well as freshwater transport processes including particle heteroaggregation, degradation and sedimentation within subcatchments. The per capita TRWP mass release estimate in the Seine watershed was 1.8 kg inhabitant-1 yr-1. The model estimates indicated that 18% of this release was transported to freshwater and 2% was exported to the estuary, which demonstrated the potential for appreciable capture, degradation, and retention of TRWP prior to export. The modeled pseudo-steady state sediment concentrations were consistent with measurements from the Seine watershed supporting the plausibility of the predicted trapping efficiency of approximately 90%. The approach supported the efficient completion of local and global sensitivity analyses presented in Part II of this study, and can be adapted to the assessment of other MPs.

Characterizing export of land-based microplastics to the estuary - Part II: Sensitivity analysis of an integrated geospatial microplastic transport modeling assessment of tire and road wear particles.

Integrated models addressing microplastic (MP) generation, terrestrial distribution, and freshwater transport are useful tools characterizing the export of MP to marine waters. In Part I of this study, a baseline watershed-scale MP mass balance model was developed for tire and road wear particles (TRWP) in the Seine watershed. In Part II, uncertainty and sensitivity analysis (SA) methods were used to identify the parameters that determine the transport of these particles to the estuary. Local differential, local range and global first-order variance-based SA identified similar key parameters. The global SA (1000 Monte Carlo simulations) indicated that most of the variance in TRWP exported to the estuary can be apportioned to TRWP diameter (76%), TRWP density (5.6%), the fraction of TRWP directed to combined sewers with treatment (3.9%), and the fraction of TRWP distributed to runoff (versus roadside soil; 2.2%). The export fraction was relatively insensitive to heteroaggregation processes and the rainfall intensity threshold for road surface washoff. The fraction of TRWP exported to estuary in the probabilistic assessment was centered on the baseline estimate of 2%. This fraction ranged from 1.4 to 4.9% (central tendency defined as 25th to 75th percentile) and 0.97% to 13% (plausible upper bound defined as 10th to 90th percentiles). This study emphasizes the importance of in situ characterization of TRWP diameter and density, and confirms the baseline mass balance presented in Part I, which indicated an appreciable potential for capture of TRWP in freshwater sediment.

A comparative evaluation of five hazard screening tools.

An increasing number of hazard assessment tools and approaches are being used in the marketplace as a means to differentiate products and ingredients with lower versus higher hazards or to certify what some call greener chemical ingredients in consumer products. Some leading retailers have established policies for product manufacturers and their suppliers to disclose chemical ingredients and their related hazard characteristics often specifying what tools to use. To date, no data exists that show a tool's reliability to provide consistent, credible screening-level hazard scores that can inform greener product selection. We conducted a small pilot study to understand and compare the hazard scoring of several hazard screening tools to determine if hazard and toxicity profiles for chemicals differ. Seven chemicals were selected that represent both natural and man-made chemistries as well as a range of toxicological activity. We conducted the assessments according to each tool provider's guidelines, which included factors such as endpoints, weighting preferences, sources of information, and treatment of data gaps. The results indicate the tools varied in the level of discrimination seen in the scores for these 7 chemicals and that tool classifications of the same chemical varied widely between the tools, ranging from little or no hazard or toxicity to very high hazard or toxicity. The results also highlight the need for transparency in describing the basis for the tool's hazard scores and suggest possible enhancements. Based on this pilot study, tools should not be generalized to fit all situations because their evaluations are context-specific. Before choosing a tool or approach, it is critical that the assessment rationale be clearly defined and matches the selected tool or approach. Integr Environ Assess Manag 2017;13:139-154. © 2016 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals, Inc. on behalf of SETAC.

Plaque thickness and morphology in psoriasis vulgaris associated with therapeutic response.

BACKGROUND: The Utah Psoriasis Initiative (UPI) is an expanding database that is being used to identify and characterize phenotypic variants of psoriasis and explore genotype-phenotype relationships. We recently reported distinct morphological variants of psoriasis that are characterized by thickness of lesions (induration) in the untreated state. OBJECTIVES: To explore the clinical relevance of these morphological variants. METHODS: For these analyses, we used the phenotypic data from 282 additional subjects gathered at enrollment into the UPI and compared their phenotype with that of the original 500 patients reported previously. The analysis was further expanded via a longitudinal follow-up of 286 subjects from the original 500 case cohort. RESULTS: Firstly, the initial findings were confirmed. Expansion of the cohort used for the original observation by about 50% and reanalysis showed that there was no alteration in the proportions of patients expressing thin- and thick-plaque disease phenotypes. Secondly, analysis of the larger cohort showed that this morphological phenotype had clinical relevance: those patients with thin-plaque disease were more likely to report a complete therapeutic response to topical corticosteroids and phototherapy. In contrast, plaque thickness did not appear to be a factor in response to systemic agents. CONCLUSIONS: Using a patient's baseline plaque morphology to choose a primary treatment modality may result in earlier disease improvement and reduce the cost of therapy.

Preliminary assessment of PCB risks to human and ecological health in the lower Passaic River.

Concentrations of Aroclor mixtures and specific polychlorinated biphenyl (PCB) congeners were measured in surface sediments and aquatic biota (striped bass fillet, mummichog, and blue crab muscle and hepatopancreas) collected from the lower Passaic River. Several of the 47 surface sediment samples contained Aroclor concentrations that exceeded a National Oceanic and Atmospheric Administration (NOAA) benchmark level for "total PCBs" (22.7 micrograms/kg). Each of the 18 PCB congeners analyzed in aquatic biota was detected in one or more tissue samples, and numerous congeners were detected in every sample (IUPAC numbers 77, 105, 114, 118, 123, 126, 156, 157, 167, and 189). PCB congener concentrations were similar to those that have been reported in fish from other waterways that contain elevated levels of PCBs. Congener 118 was present at the highest concentration in almost all samples, and constituted 14-60% of the total PCB mass (sum of all congener masses) measured in any given tissue sample. In spite of the prevalence of PCB congeners in biota tissues (up to 1314 micrograms/kg total PCBs), Aroclors were not detected in bass or crab samples at a limit of detection of 33-55 micrograms/kg. This anomaly may be due to selective degradation of certain PCB congeners that are used to analytically recognize and quantitate Aroclors. Using the measured sediment concentrations, a food web model accurately predicted blue crab muscle concentrations of individual PCB congeners (typically within a factor of two) and was also fairly accurate for mummichog (typically within an order of magnitude). Concentrations in striped bass fillet were underestimated by factors of approximately 20-140. Increased cancer risk estimates associated with fish and crab consumption were obtained using four different methods. Using Aroclor tissue concentrations (one-half the limit of detection) and an Aroclor slope factor, total risks were 2.6 x 10(-6); using the "total PCB" measurements and an Aroclor slope factor, total risks were 1.9 x 10(-5); the "PCB-TEQ" method yielded total risks of 6.5 x 10(-4); and USEPA's recent suggested approach for evaluating "dioxin-like" and non-"dioxin-like" effects resulted in a total risk of 6.6 x 10(-4). This wide range in risk estimates indicates that it is critical to the risk management decision-making process that data requirements and risk assessment objectives be carefully evaluated early in the investigation process.

Urinary chromium as a biological marker of environmental exposure: what are the limitations?

Public concern has mounted recently about environmental exposures to chromium in soil, tap water, and ambient air. In response, agencies charged with protecting public health have attempted to study exposure by monitoring urinary chromium levels among potentially exposed populations. While urinary biomonitoring of occupationally exposed workers has been successfully used to assess high-level inhalation exposures in the workplace, evaluating low-level environmental exposures has been problematic. Due to these problems, before an extensive biological monitoring study is conducted of those exposed to low levels of environmental chromium, several issues must be resolved. First, exposures to chromium must occur at the same time as sampling, because the biological half-life of chromium in urine is very short (less than 2 days). Second, reduced bioavailability and bioaccessibility via the oral and dermal routes of exposure limit the capacity of urinary monitoring to measure environmental exposures (e.g., systemic dose is too small to be measured). Third, the dose of chromium must be sufficient such that it may be reliably measured above background levels in urine (range of 0.2 to 2 microg/liter) and above the analytical limit of detection (0.2 microg/liter). Fourth, the inter- and intrapersonal variability in background levels of urinary chromium is known to be significant and influenced by food and beverage intake, smoking, and exercise. Thus, the role of each factor must be carefully understood. Finally, it is imperative to have developed a complete understanding of the clinical significance of elevated urinary chromium levels before a study is performed, because higher than background levels, in and of themselves, are not indicative of a significant health concern. The route of exposure, valence of chromium to which people were exposed, exposure time, and duration must all be understood before the biological data can be implemented. We have conducted a total of nine human exposure studies over the past 3 years in an attempt to understand the kinetics of chromium and the impact on urinary, red blood cell (RBC), and plasma biomonitoring programs. The results of these studies are described here and our recommendations are offered for how to design and implement a urinary chromium biomonitoring study. In our view, given some evidence that the dose of hexavalent chromium [Cr(VI)] is sufficient to be measurable above background concentrations of total chromium [Cr(III) and Cr(VI)], duplicated measurements of chromium in plasma and RBCs are, in most cases, a more definitive gauge of environmental exposure than urinary biomonitoring.