Modeled Vegetation Community Trajectories: Effects from Climate Change, Atmospheric Nitrogen Deposition, and Soil Acidification Recovery.

Forest understory plant communities in the United States harbor most of the vegetation diversity of forests and are often sensitive to changes in climate and atmospheric deposition of nitrogen (N). As temperature increases from human-caused climate change and soils recover from long term atmospheric deposition of N and sulfur (S), it is unclear how these important ecosystem components will respond. We used the newly developed US-PROPS model - based on species response functions for over 1,500 species - to evaluate the potential impacts of atmospheric N deposition and climate change on species occurrence probability for a case study in the forested ecosystems of the Great Smoky Mountains National Park (GRSM), an iconic park in the southeastern United States.

ToxicR: A computational platform in R for computational toxicology and dose-response analyses.

The need to analyze the complex relationships observed in high-throughput toxicogenomic and other omic platforms has resulted in an explosion of methodological advances in computational toxicology. However, advancements in the literature often outpace the development of software researchers can implement in their pipelines, and existing software is frequently based on pre-specified workflows built from well-vetted assumptions that may not be optimal for novel research questions. Accordingly, there is a need for a stable platform and open-source codebase attached to a programming language that allows users to program new algorithms.

Continuous Model Averaging for Benchmark Dose Analysis: Averaging Over Distributional Forms.

When estimating a benchmark dose (BMD) from chemical toxicity experiments, model averaging is recommended by the National Institute for Occupational Safety and Health, World Health Organization and European Food Safety Authority. Though numerous studies exist for Model Average BMD estimation using dichotomous responses, fewer studies investigate it for BMD estimation using continuous response. In this setting, model averaging a BMD poses additional problems as the assumed distribution is essential to many BMD definitions, and distributional uncertainty is underestimated when one error distribution is chosen a priori.

Case studies to explore the optimal use of randomized and nonrandomized studies in evidence syntheses that use GRADE.

Objectives: Randomized controlled trials (RCTs) are the preferred source of evidence for the relative effect of healthcare interventions summarized in knowledge syntheses. Nonrandomized studies of interventions (NRSI) may provide replacement, sequential, or complementary evidence to RCTs. The Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach can provide different options for properly using RCTs and NRSI integrated in health syntheses.

GRADE guidance 24 optimizing the integration of randomized and non-randomized studies of interventions in evidence syntheses and health guidelines.

Background And Objective: This is the 24th in the ongoing series of articles describing the GRADE approach for assessing the certainty of a body of evidence in systematic reviews and health technology assessments and how to move from evidence to recommendations in guidelines.

Methods: Guideline developers and authors of systematic reviews and other evidence syntheses use randomized controlled studies (RCTs) and non-randomized studies of interventions (NRSI) as sources of evidence for questions about health interventions. RCTs with low risk of bias are the most trustworthy source of evidence for estimating relative effects of interventions because of protection against confounding and other biases.

Evaluation of the health impacts of the 1990 Clean Air Act Amendments using causal inference and machine learning.

We develop a causal inference approach to estimate the number of adverse health events that were prevented due to changes in exposure to multiple pollutants attributable to a large-scale air quality intervention/regulation, with a focus on the 1990 Clean Air Act Amendments (CAAA). We introduce a causal estimand called the Total Events Avoided (TEA) by the regulation, defined as the difference in the number of health events expected under the no-regulation pollution exposures and the number observed with-regulation. We propose matching and machine learning methods that leverage population-level pollution and health data to estimate the TEA.

Consideration of spatial and temporal scales in stream restorations and biotic monitoring to assess restoration outcomes: A literature review, Part 1.

Stream and river restoration practices have become common in many parts of the world. We ask the question whether such restorations improve freshwater biotic assemblages or functions over time, and if not, can general reasons be identified for such outcomes. We conducted a literature survey and review of studies in which different types of stream restorations were conducted and outcomes reported.

Consideration of spatial and temporal scales in stream restorations and biotic monitoring to assess restoration outcomes: A literature review, Part 2.

Stream and river restoration practices have become common in many parts of the world. To answer the question whether such restoration measures improve freshwater biotic assemblages or functions over time, and if not, can general reasons be identified for such outcomes, we conducted a literature survey and review of studies in which different types of stream restorations were conducted and outcomes assessed. In the first paper, we reviewed studies of culvert restorations, acid mine drainage or industrial pollution restoration; and urban stream restoration projects.

ExpoKids: An R-based tool for characterizing aggregate chemical exposure during childhood.

Background: Aggregate exposure, the combined exposures to a single chemical from all pathways, is a critical children's health issue.

Objective: The primary objective is to develop a tool to illustrate potential differences in aggregate exposure at various childhood lifestages and the adult lifestage.

Methods: We developed ExpoKids (an R-based tool) using oral exposure estimates across lifestages generated by US EPA's Exposure Factors Interactive Resource for Scenarios Tool (ExpoFIRST).

Review of Laboratory Scale Models of Karst Aquifers: Approaches, Similitude, and Requirements.

This review focuses on investigations of groundwater flow and solute transport in karst aquifers through laboratory scale models (LSMs). In particular, LSMs have been used to generate new data under different hydraulic and contaminant transport conditions, testing of new approaches for site characterization, and providing new insights into flow and transport processes through complex karst aquifers. Due to the increasing need for LSMs to investigate a wide range of issues, associated with flow and solute migration karst aquifers this review attempts to classify, and introduce a framework for constructing a karst aquifer physical model that is more representative of field conditions.

Taxonomic harmonization may reveal a stronger association between diatom assemblages and total phosphorus in large datasets.

Diatom data have been collected in large-scale biological assessments in the United States, such as the U.S. Environmental Protection Agency's National Rivers and Streams Assessment (NRSA).

Uptake of Sulfate from Ambient Water by Freshwater Animals.

To better understand how the sulfate (SO ) anion may contribute to the adverse effects associated with elevated ionic strength or salinity in freshwaters, we measured the uptake and efflux of SO in four freshwater species: the fathead minnow (, Teleostei: Cyprinidae), paper pondshell (, Bivalvia: Unionidae), red swamp crayfish (, Crustacea: Cambaridae), and two-lined mayfly (, Insecta: Ephemeridae). Using / stable isotope ratios and the concentrations of S and SO , we measured the SO influx rate ( ), net flux ( ), and efflux rate (J) during a 24 h exposure period. For all four species, the means of for SO were positive, and was significantly greater than 0 at both target SO concentrations in the fish and mollusk and at the lower SO concentration in the crayfish.

Quantitative Risk Assessment: Developing a Bayesian Approach to Dichotomous Dose-Response Uncertainty.

Model averaging for dichotomous dose-response estimation is preferred to estimate the benchmark dose (BMD) from a single model, but challenges remain regarding implementing these methods for general analyses before model averaging is feasible to use in many risk assessment applications, and there is little work on Bayesian methods that include informative prior information for both the models and the parameters of the constituent models. This article introduces a novel approach that addresses many of the challenges seen while providing a fully Bayesian framework. Furthermore, in contrast to methods that use Monte Carlo Markov Chain, we approximate the posterior density using maximum a posteriori estimation.

Threshold effects of air pollution and climate change on understory plant communities at forested sites in the eastern United States.

Forest understory plant communities in the eastern United States are often diverse and are potentially sensitive to changes in climate and atmospheric inputs of nitrogen caused by air pollution. In recent years, empirical and processed-based mathematical models have been developed to investigate such changes in plant communities. In the study reported here, a robust set of understory vegetation response functions (expressed as version 2 of the Probability of Occurrence of Plant Species model for the United States [US-PROPS v2]) was developed based on observations of forest understory and grassland plant species presence/absence and associated abiotic characteristics derived from spatial datasets.

On Tracer Breakthrough Curve Dataset Size, Shape, and Statistical Distribution.

A tracer breakthrough curve (BTC) for each sampling station is the ultimate goal of every quantitative hydrologic tracing study, and dataset size can critically affect the BTC. Groundwater-tracing data obtained using automatic sampling or detection devices may result in very high-density data sets. Data-dense tracer BTCs obtained using devices and stored in dataloggers can result in visually cluttered overlapping data points.

Evaluation of Developmental Toxicity, Developmental Neurotoxicity, and Tissue Dose in Zebrafish Exposed to GenX and Other PFAS.

Background: Per- and polyfluoroalkyl substances (PFAS) are a diverse class of industrial chemicals with widespread environmental occurrence. Exposure to long-chain PFAS is associated with developmental toxicity, prompting their replacement with short-chain and fluoroether compounds. There is growing public concern over the safety of replacement PFAS.

Disparities in Distribution of Particulate Matter Emissions from US Coal-Fired Power Plants by Race and Poverty Status After Accounting for Reductions in Operations Between 2015 and 2017.

To investigate potential changes in burdens from coal-fired electricity-generating units (EGUs) that emit fine particulate matter (PM, defined as matter with a nominal mean aerodynamic diameter of ≤ 2.5 µm) among racial/ethnic and economic groups after reduction of operations in 92 US EGUs. PM burdens calculated for EGUs listed in the 2008, 2011, and 2014 National Emissions Inventory were recalculated for 2017 after omitting emissions from 92 EGUs.

Disinfection By-Product Exposures and the Risk of Musculoskeletal Birth Defects.

Background: Epidemiological studies suggest that exposure to water disinfection by-products (DBPs) may increase the risk of certain birth defects. However, evidence for musculoskeletal defects (MSDs) is limited. Previous MSD studies have not examined DBPs beyond trihalomethanes (THMs) and have not separately examined limb or diaphragm defects which may have distinct developmental etiologies.

Positive correlation between wood N and stream nitrate concentrations in two temperate deciduous forests.

A limitation to understanding drivers of long-term trends in terrestrial nitrogen (N) availability in forests and its subsequent influence on stream nitrate export is a general lack of integrated analyses using long-term data on terrestrial and aquatic N cycling at comparable spatial scales. Here we analyze relationships between stream nitrate concentrations and wood N records (n = 96 trees) across five neighboring headwater catchments in the Blue Ridge physiographic province and within a single catchment in the Appalachian Plateau physiographic province in the eastern United States. Climatic, acidic deposition, and forest disturbance datasets were developed to elucidate the influence of these factors on terrestrial N availability through time.

Phthalate exposure and neurodevelopment: A systematic review and meta-analysis of human epidemiological evidence.

Objective: We performed a systematic review of the epidemiology literature to identify the neurodevelopmental effects associated with phthalate exposure.

Data Sources And Study Eligibility Criteria: Six phthalates were included in the review: di(2-ethylhexyl) phthalate (DEHP), diisononyl phthalate (DINP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), butyl benzyl phthalate (BBP), and diethyl phthalate (DEP). The initial literature search (of PubMed, Web of Science, and Toxline) included all studies of neurodevelopmental effects in humans, and outcomes were selected for full systematic review based on data availability.