Environmental Protection Agency Toxicity Research Articles

Residential proximity to toxic metal-emitting industrial sites and toenail metal concentrations in a United States-wide prospective cohort

BackgroundIndustrial facilities across the United States (US) release millions of pounds of toxic chemicals, including metals. Exposure to toxic metals has been associated with adverse health outcomes, but there is limited evidence on the association between living near metal-releasing facilities and the body burden of emitted compounds. ObjectiveTo investigate the association between residential proximity to toxic metal-emitting industrial facilities and toenail metal concentrations and to evaluate whether associations differed by race. MethodsIn a sample of 1556 non-Hispanic Black (32.5%) and non-Hispanic White (67.5%) women from the Sister Study, we used the US Environmental Protection Agency Toxics Release Inventory to identify metal-emitting facilities within 3, 5, and 10 km of participants’ baseline residences. We measured toenail concentrations (μg/g) of arsenic, cadmium, cobalt, chromium, and lead. Using multivariable linear regression, we examined associations between residential proximity to and emissions from metal-emitting facilities and toenail metal concentrations, stratifying by race. We explored modification of race-stratified associations by neighborhood deprivation, using the Area Deprivation Index (ADI). ResultsBlack participants were more likely to reside within 3 km of chromium-releasing facilities and 5 and 10 km of all observed metal-emitting sites. Living near metal-releasing facilities was not associated with higher toenail metal concentrations overall. Among Black women, higher chromium emissions exposure was associated with higher toenail chromium levels (βTertile3vs.non-exposed = 2.36 μg/g, 95% CI = 0.63, 4.10). An association with lead was observed among Black women residing in the most deprived areas (≥75th ADI percentile: β = 3.08 μg/g, 95% CI = 1.46, 4.71). No associations were observed for White participants. ConclusionsDespite low exposure prevalence, our findings suggest that living near chromium- and lead-releasing facilities, especially at shorter distances, may be associated with higher corresponding toenail metal levels among Black women, particularly those residing in the most disadvantaged areas.

The ToxCast pipeline: updates to curve-fitting approaches and database structure.

Introduction: The US Environmental Protection Agency Toxicity Forecaster (ToxCast) program makes in vitro medium- and high-throughput screening assay data publicly available for prioritization and hazard characterization of thousands of chemicals. The assays employ a variety of technologies to evaluate the effects of chemical exposure on diverse biological targets, from distinct proteins to more complex cellular processes like mitochondrial toxicity, nuclear receptor signaling, immune responses, and developmental toxicity. The ToxCast data pipeline (tcpl) is an open-source R package that stores, manages, curve-fits, and visualizes ToxCast data and populates the linked MySQL Database, invitrodb. Methods: Herein we describe major updates to tcpl and invitrodb to accommodate a new curve-fitting approach. The original tcpl curve-fitting models (constant, Hill, and gain-loss models) have been expanded to include Polynomial 1 (Linear), Polynomial 2 (Quadratic), Power, Exponential 2, Exponential 3, Exponential 4, and Exponential 5 based on BMDExpress and encoded by the R package dependency, tcplfit2. Inclusion of these models impacted invitrodb (beta version v4.0) and tcpl v3 in several ways: (1) long-format storage of generic modeling parameters to permit additional curve-fitting models; (2) updated logic for winning model selection; (3) continuous hit calling logic; and (4) removal of redundant endpoints as a result of bidirectional fitting. Results and discussion: Overall, the hit call and potency estimates were largely consistent between invitrodb v3.5 and 4.0. Tcpl and invitrodb provide a standard for consistent and reproducible curve-fitting and data management for diverse, targeted in vitro assay data with readily available documentation, thus enabling sharing and use of these data in myriad toxicology applications. The software and database updates described herein promote comparability across multiple tiers of data within the US Environmental Protection Agency CompTox Blueprint.

Residential Proximity to Carcinogenic Industrial Air Emissions and Breast Cancer Incidence in a United States-Wide Prospective Cohort

Purpose: To evaluate whether residential proximity to air emissions of correlated industrial carcinogens, both singly and in combination, are associated with breast cancer incidence. Methods: Using the US Environmental Protection Agency's Toxics Release Inventory, we estimated the 10-year annual average air releases of 26 known or probable carcinogens within 3, 5, and 10 km of Sister Study participants' baseline residences (n = 50,343, 2003–2009). We used Cox proportional hazards regression to estimate adjusted hazard ratios (HR) and 95% confidence intervals (CI) for the association between ambient concentrations of each individual compound and incident breast cancer. To assess mixtures, we applied an exposure continuum mapping (ECM) framework to identify latent mixture profiles via a self-organizing map and assessed whether these profiles were related to incident breast cancer by estimating a joint exposure-response function with generalized additive models. Results: During follow-up (mean = 11.6 years), 4,282 breast cancer cases were identified. The exposure prevalence for compounds emitted within 3-km of participants' residences varied from <1%–15%. For individual compounds, HRs for the association between quantiles of emission levels and breast cancer were largely null, except for cadmium, vinyl chloride and asbestos (e.g., asbestos 3-km HR>median vs. no exposure = 2.61, 95% CI: 1.37–5.09). Our application of ECM identified 49 profiles that explained 79% of the variance in emission patterns observed within 3-km of participant residences. Profiles revealed that relatively high levels of exposure to several compounds were rare (<1%) and most participants resided in locations defined by low emissions patterns. Estimation of a joint exposure-response surface indicated that breast cancer was not significantly related to changing patterns of the composition of emission mixtures (P = 0.31). Conclusions: Preliminary results suggest that breast cancer incidence may be related to emissions of certain individual industrial carcinogens, particularly asbestos. Examination of complex exposure scenarios revealed that high simultaneous exposure to many compounds was rare, and that our identified latent patterns of these emissions were not associated with breast cancer.

Probabilistic Points of Departure and Reference Doses for Characterizing Human Noncancer and Developmental/Reproductive Effects for 10,145 Chemicals.

Regulatory toxicity values used to assess and manage chemical risks rely on the determination of the point of departure (POD) for a critical effect, which results from a comprehensive and systematic assessment of available toxicity studies. However, regulatory assessments are only available for a small fraction of chemicals. Using invivo experimental animal data from the U.S. Environmental Protection Agency's Toxicity Value Database, we developed a semiautomated approach to determine surrogate oral route PODs, and corresponding toxicity values where regulatory assessments are unavailable. We developed a curated data set restricted to effect levels, exposure routes, study designs, and species relevant for deriving toxicity values. Effect levels were adjusted to chronic human equivalent benchmark doses (). We hypothesized that a quantile of the distribution could serve as a surrogate POD and determined the appropriate quantile by calibration to regulatory PODs. Finally, we characterized uncertainties around the surrogate PODs from intra- and interstudy variability and derived probabilistic toxicity values using a standardized workflow. The distribution for each chemical was adequately fit by a lognormal distribution, and the 25th percentile best predicted the available regulatory PODs [, units]. We derived surrogate PODs for 10,145 chemicals from the curated data set, differentiating between general noncancer and reproductive/developmental effects, with typical uncertainties (at 95% confidence) of a factor of 10 and 12, respectively. From these PODs, probabilistic reference doses (1% incidence at 95% confidence), as well as human population effect doses (10% incidence), were derived. In providing surrogate PODs calibrated to regulatory values and deriving corresponding toxicity values, we have substantially expanded the coverage of chemicals from 744 to 8,023 for general noncancer effects, and from 41 to 6,697 for reproductive/developmental effects. These results can be used across various risk assessment and risk management contexts, from hazardous site and life cycle impact assessments to chemical prioritization and substitution. https://doi.org/10.1289/EHP11524.

Environmental mixtures and breast cancer: identifying co-exposure patterns between understudied vs breast cancer-associated chemicals using chemical inventory informatics.

Although evidence linking environmental chemicals to breast cancer is growing, mixtures-based exposure evaluations are lacking. This study aimed to identify environmental chemicals in use inventories that co-occur and share properties with chemicals that have association with breast cancer, highlighting exposure combinations that may alter disease risk. The occurrence of chemicals within chemical use categories was characterized using the Chemical and Products Database. Co-exposure patterns were evaluated for chemicals that have an association with breast cancer (BC), no known association (NBC), and understudied chemicals (UC) identified through query of the Silent Spring Institute's Mammary Carcinogens Review Database and the U.S. Environmental Protection Agency's Toxicity Reference Database. UCs were ranked based on structure and physicochemical similarities and co-occurrence patterns with BCs within environmentally relevant exposure sources. A total of 6793 chemicals had data available for exposure source occurrence analyses. 50 top-ranking UCs spanning five clusters of co-occurring chemicals were prioritized, based on shared properties with co-occuring BCs, including chemicals used in food production and consumer/personal care products, as well as potential endocrine system modulators. Results highlight important co-exposure conditions that are likely prevalent within our everyday environments that warrant further evaluation for possible breast cancer risk. Most environmental studies on breast cancer have focused on evaluating relationships between individual, well-known chemicals and breast cancer risk. This study set out to expand this research field by identifying understudied chemicals and mixtures that may occur in everyday environments due to their patterns of commercial use. Analyses focused on those that co-occur alongside chemicals associated with breast cancer, based upon in silico chemical database querying and analysis. Particularly in instances when understudied chemicals share physicochemical properties and structural features with carcinogens, these chemical mixtures represent conditions that should be studied in future clinical, epidemiological, and toxicological studies.

Ambient air exposures to arsenic and cadmium and overall and prostate cancer-specific survival among prostate cancer cases in Pennsylvania, 2004 to 2014.

Exposures to arsenic (As) and cadmium (Cd) have been associated with higher prostate cancer (PC) mortality; however, these associations have been inconsistent. The authors investigated whether higher ambient air concentrations of As and Cd are associated with lower overall and PC-specific survival among PC cases in Pennsylvania. Incident PC cases of patients, aged 40 years or older, with a clinical diagnosis and nonmetastatic disease were identified in the 2004 to 2014 Pennsylvania Cancer Registry. Demographic, clinical, and pathologic information were extracted from the Pennsylvania Cancer Registry. The 3- and 5-year average and cumulative air concentrations of As and Cd were extracted from the Environmental Protection Agency's Toxics Release Inventory database. Spatial-temporal hierarchical accelerated failure time models were used to examine the associations between air concentrations of As and Cd and overall and PC-specific survival for the total population and stratified by geographical region defined by rurality and Appalachia status, after adjusting for confounders. There were 78,914 PC cases included. Increasing 3- and 5-year average and cumulative air concentrations of As and Cd were significantly associated with lower overall and PC-specific survival among cases, after adjusting for confounders, for the total population, and stratified by geographical region for most of the estimates. Data suggest that increasing ambient air exposures to As and Cd may play a role in overall and PC-specific mortality risk among PC cases. Exposures to As and Cd are modifiable and may provide insight into potential strategies to improve PC health outcomes. Arsenic and cadmium exposures linked to increased prostate cancer deaths remain unclear. We investigated whether air levels of arsenic and cadmium reported to be released from industries decrease overall and prostate cancer-specific survival among prostate cancer cases identified in the 2004 to 2014 Pennsylvania Cancer Registry. Among the 78,914 prostate cancer cases, increasing air levels of arsenic and cadmium are found to be associated with lower overall and prostate cancer-specific survival for the total population and within rural and urban Appalachia and urban non-Appalachia counties in Pennsylvania. Reducing exposures to arsenic and cadmium have the potential to decrease prostate cancer deaths.

Identification of newly formed toxic chemicals in E-cigarette aerosols with Orbitrap mass spectrometry and implications on E-cigarette control.

The increasing use of electronic nicotine delivery systems (ENDS) is of concern due to multiple emerging adverse health effects. Most analyses of the harmful chemicals of ENDS have targeted metals or carbonyls generated by thermal decomposition of carrier liquids such as propylene glycol. However, new complex compounds not routinely identified and with unknown health consequences could be formed. ENDS aerosol samples were collected by the direct aerosol droplet deposition method. Untargeted analysis was performed using Orbitrap mass spectrometry with high mass accuracy. We identified more than 30 "features" in the aerosol characterized by pairs of the mass-to-charge ratio "m/z" of the compound and the retention time. We identified several compounds containing nicotine and propylene glycol (NIC-PG), whose abundance relative to nicotine increased along with vaping power used. On the basis of the prediction by the Environmental Protection Agency Toxicity Estimation Software Tool, these compounds exert developmental toxicity. In addition, a nitrogen-containing compound, likely tributylamine (a known lung irritant), was identified based on the molecular weight. This compound has not been previously identified in ENDS e-liquids and aerosols. ENDS produce not only small toxic compounds such as aldehydes, but also large complex toxic compounds such as NIC-PG. Predicted development toxicity for NIC-PG is concerning for fetal development in pregnant women who use ENDS, children exposed to secondhand or thirdhand ENDS aerosols, and teenage ENDS users whose brains are still developing. The strong positive association between NIC-PG levels and ENDS power output supports regulating high-powered ENDS.

The impact of toxic chemical releases and their management on financial performance

This paper examines the extent to which environmental performance affects firm profitability, where environmental performance is measured by toxic chemical releases per sales dollar and toxic chemical management (treat, recycle, or recovery) per sales dollar. Conclusions are drawn based on a sample of U.S.-based publicly-traded companies that reported to the Environmental Protection Agency's Toxics Release Inventory (TRI) program between 2001 and 2017. The results show that publicly-traded companies that reduce emissions see an increase in their Tobin's q. In addition, the effects of reducing emissions, treating toxic chemicals to minimize their environmental impact, or combusting toxic chemicals for energy, are more significant for companies that consistently fall under the mandatory reporting requirements of the TRI program. However, recycling toxic chemicals is associated with negative financial consequences for these companies.

Promoted elimination of antibiotic sulfamethoxazole in water using sodium percarbonate activated by ozone: Mechanism, degradation pathway and toxicity assessment

Herein, sodium percarbonate (SPC), an effective and environment-friendly oxidant, was activated by ozone (O3) for promoting elimination of sulfamethoxazole (SMX) in water. The effect of various parameters including SPC dosage, O3 dosage, SPC concentration, pH value and radical scavenger on SPC elimination was investigated firstly. Results showed that with increase of SMX dosage, the removal efficiency of SMX firstly improved and then declined. With optimal SPC dosage of 0.2 g/L, the removal efficiency of SMX rose by 16.4%, and corresponding kinetic constant multiplied by 1.7 times. Improving O3 dosage and reducing SMX concentration were beneficial to SMX elimination. Compared with acidic and neutral conditions, alkaline condition was favorable for SMX elimination. Radical trapping experiment showed that 1O played an important role during SMX decomposition. SPC addition could promote OH production in O3 system. The comparison of active species in different reaction system suggested that OH and O2− also play crucial role for SMX elimination. TOC and COD removal were all enhanced after 30 min treatment in O3/SPC system. Degradation process of SMX was inspected via UV–Vis spectra, pH variation, conductivity variation and ammonia nitrogen variation. The degradation pathway was predicted by discrete Fourier transform (DFT) coupled with literatures. Finally, the toxicity of degradation intermediates was evaluated by US Environmental Protection Agency Toxicity Estimation Software Tool (US-EPA-TEST).

Impact of droughts on industrial emissions into surface waters.

In this paper, we examine the impact of droughts on industrial emissions into surface waters and transfers to publicly owned treatment works (POTWs). We use industrial discharges into surface waters data from the US Environmental Protection Agency's Toxics Release Inventory (TRI) database. We employ runoffs normalized using previous 61-year average runoffs as a proxy for drought. We match both the discharges into surface waters and the runoffs at the 8-digit hydrologic unit code (HUC) level. Our analysis indicates that normalized runoffs of the current and previous years positively influence industrial emissions into surface waters. We also find that the impact of uneven availability of water on emissions is higher on larger facilities. Normalized runoffs of the current and previous years do not have a statistically significant influence on transfers to publicly owned treatment works. However, normalized runoffs of the previous year do affect transfers of larger facilities. Businesses are dependent on water not only for their operations but to discharge their pollutants as well. Climate change will increase the frequency and intensity of droughts and floods. Therefore, every business that requires significant quantities of water must plan to cope with uneven availability of water.

Magnetic Ni-Zn spinel ferrite nanopowder from toxic Zn-bearing electric arc furnace dust: A promising treatment process

Zn-bearing electric arc furnace dust (ZEAFD) generated as a by-product of steel manufacture is classified as a toxic solid waste. To date, there has been little research concerning facile and efficient utilization of the valuable metallic elements (such as Zn, Fe, Mn and Cr) in this material. In this study, a metal co-doped (Ni,Zn)Fe2O4 nanopowder having excellent magnetic properties was successfully synthesized by a solid state calcination method based on adding Ni(OH)2 to the ZEAFD to compensate for a lack of divalent ions. The effects of the ZEAFD to Ni(OH)2 mass ratio and of the calcination temperature on the phase transformations, microstructures and magnetic characteristics of the resulting ferrites were investigated using various analytic techniques. A pure phase metal co-doped (Ni,Zn)Fe2O4 nanopowder having a higher saturation magnetization (57.3 emu·g−1) and lower coercivity (58.8 Oe) was obtained when the mixture was calcined at 1000 °C for 2 h with a mass ratio of 2:0.9, followed by washing with dilute acetic acid (pH = 2.88). This synthesized metal co-doped ferrite was also assessed using the United States Environmental Protection Agency toxicity characteristic leaching procedure and found to be non-toxic. This process provided overall dust utilization percentages as high as 76.0%.

Incorporating ToxCast™ data into naphthalene human health risk assessment

Chronic inhalation of naphthalene causes nasal olfactory epithelial tumors in rats and benign lung adenomas in mice. The available human data do not establish an association between naphthalene and increased respiratory cancer risk. Therefore, cancer risk assessment of naphthalene in humans depends predominantly on experimental evidence from rodents. The United States Environmental Protection Agency's (US EPA) Toxicity Forecaster (ToxCast™) database contains data from 710 in vitro assays for naphthalene, the majority of which were conducted in human cells. Of these assays, only 18 were active for naphthalene, and all were in human liver cells. No assays were active in human bronchial epithelial cells. In our analysis, all of the active naphthalene ToxCast assay data were reviewed and used to: 1) determine naphthalene human inhalation concentrations corresponding to relevant activity concentrations for all active naphthalene assays, using a physiologically based pharmacokinetic (PBPK) model; and 2) evaluate the transcriptional responses for active assays in the context of consistency with the larger naphthalene data set and proposed modes of action (MoAs) for naphthalene toxicity and carcinogenicity. The transcriptional responses in liver cells largely reflect cellular activities related to oxidative stress and chronic inflammation. Overall, the results from our analysis of the active ToxCast assays for naphthalene are consistent with conclusions from our earlier weight-of-evidence evaluation for naphthalene carcinogenesis.

AORN Position Statement on Environmental Responsibility

<scp>AORN</scp> Position Statement on Environmental Responsibility

Characterizing disproportionality in facility-level toxic releases in US manufacturing, 1998–2012

The relationship between economic activity and environmental pollution is a topic of extensive research. Although a proportional relationship between the two is often the default assumption, emerging scholarship suggests that polluting releases are disproportionally distributed across units of production. This paper examines if proportionality or disproportionality best characterizes the production of toxic pollution in US manufacturing from 1998 to 2012. Examining US Environmental Protection Agency Toxics Release Inventory data from over 25 000 facilities in 322 industries, we find consistently high levels of disproportionality across facility-level toxic releases within industries, even when controlling for facility size. Moreover, high levels of within industry disproportionality are remarkably stable over the fifteen-year study period. In other words, year by year a small handful of egregiously polluting facilities account for the vast majority of toxic releases within a given industry. Our findings suggest that disproportionality should be understood as the default pattern of pollution generation rather than an exceptional case and that policymakers should seek to reduce pollution via carefully considered targeting strategies rather than broad-stroke decision making.

PCN50 MACHINE LEARNING MODELING AND EXPOSURE ASSESSMENT OF ENVIRONMENTAL TOXICANTS ON COLORECTAL CANCER MORTALITY

To generate an optimal predictive model combining environmental toxicants and known individual and contextual predictors contributing to colorectal cancer (CRC) mortality using a machine-learning framework (ML). Five conventional supervised ML models were used to develop optimal combinations of individual and contextual covariates with environmental exposures variables. The methodology is based on a classification algorithm and regression techniques to better understand the causal inference from individual and contextual level data, as well as environmental exposures data on CRC mortality. The main outcome is CRC patient's vital status (dead vs. alive). This variable is used to predict the all-cause mortality likelihood. Sources of data include the Sentara Cancer Registry, 2010 Census datasets, and Environmental Protection Agency Toxics Release Inventory. Logistic regression was used to predict mortality alongside with the latest methods for prediction using a supervised ML method: Decision Tree, Forest Gradient Boosting, Neural Network, and Bayesian Network. The ‘Best model’ was chosen based on the Area Under the Curve (AUC) value, Kolmogorov-Smirnov (KS) chart or the Youden index, and Root Average Squared Error (RASE). The data linkage resulted in a dataset containing 202 variables that include 16 patient characteristics variables, 3 socio-economic status variables, and 183 chemical-related variables. AUC for the prediction algorithms ranged from 0.5 to 0.77, the KS (Youden) ranged from 0 to 0.4185, and the RASE from 0.4409 to 0.4924. Based on these three statistics, it appears that the Forest Gradient Boosting algorithm is the best predictive model for these data. The model includes 53 important variables of which 35 were environmental covariates. The classical logistic regression included only four variables out of the 202 total variables, and none of them were chemical-related variables. This study contributes to the scientific innovation of leveraging mixed-methods data collection by building a comprehensive database for cancer research.

A comparison of waste leaching determination methods in the context of dewatered oil sands fine tailings

Leaching tests are an important component in assessing the potential of contaminants to leach from waste materials to the environment. Numerous leaching test protocols have been developed for different applications. In this study, we compare four different methods in the context of assessing leaching of inorganic ions from oil sands tailings. The four methods compared were: United States Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure; ASTM D6234; ASTM D3987; and what we refer to as the Deionized method (modified from Syncrude Analytical Aqueous Extraction of Oil Sand Method 1.7). It was found that the EPA Toxicity Characteristic Leaching Procedure generally resulted in the highest ion concentrations. The EPA method had statistically different results for three of the four tailings mixes when compared with the other three leaching methods. For Mo and Ti the EPA method always resulted in the lowest concentrations compared with the other methods, and As, Tl, and Pb sometimes resulted in the lowest concentrations. The other three leaching protocols resulted in similar dissolved ion concentrations.

Profiling 58 compounds including cosmetic-relevant chemicals using ToxRefDB and ToxCast

Safety assessment for cosmetic-relevant chemicals (CRCs) in the European Union has been reshaped by restrictions on animal testing, and new approach methodologies (NAMs) for predicting toxicity are critical to ensure new cosmetic product safety. To demonstrate NAMs for safety assessment, we surveyed in vitro bioactivity and in vivo systemic toxicity data in the US Environmental Protection Agency's (EPA's) Toxicity Forecaster (ToxCast) and Toxicity Reference databases (ToxRefDB), respectively, for 58 chemicals identified as CRCs, including cosmetic ingredients as well as trace contaminants. CRCs were diverse in use types as suggested by broad chemical use categories. In terms of both target organ effects and study type, the median of the lowest effect level (LEL) doses in ToxRefDB for CRCs tended to be slightly higher than the median for the remaining 928 chemicals with study data in ToxRefDB, though the ranges of LELs were similar. For 17 of the 58 CRCs, high-throughput toxicokinetic data were used to calculate administered equivalent doses (AEDs) in mg/kg/day units for the in vitro bioactivity observed, and these AEDs served as conservative estimators of the systemic LELs observed in vivo. This work suggests that NAMs for bioactivity may inform a conservative point-of-departure estimate for diverse CRCs.

Trump Administration stymies US EPA's chemical carcinogenicity and toxicity assessments.

The Trump Administration is stymying the US Environmental Protection Agency (EPA)'s assessments of chemical toxicity and carcinogenicity, according to the US Government Accountability Office (GAO), congressional testimony, and experts contacted by The Lancet Oncology.

Removal and fixation of arsenic by forming a complex precipitate containing scorodite and ferrihydrite

For the metallurgical industries, the safe disposal of arsenic-bearing waste is animportant issue. In this study, a two-stage arsenic precipitation process was proposed, which consists of formation of scorodite at lower pH followed by precipitation of arsenical ferrihydrite at higher pH. The experimental results show that arsenic can be removed effectively from a solution with arsenic concentration of 5 g/L as precipitate of crystalline scorodite through oxidizing ferrous ions with air stream at pH of 2at first. Then, the pH value was raised to 3 and 4, and almost all the residual arsenic was removed from the solution due to adsorption onto amorphous ferrihydrite at the molar ratio of Fe/As between 2 and 4. The United States Environmental Protection Agency's Toxicity Characteristic Leaching Procedure tests demonstrate that the complex precipitates generated under these conditions (Fe/As ratio of 4, final pH between 3 and 4) were very stable and no leached arsenic can be detected using acetic acid buffer solution (pH 4.93 ± 0.05) in tests of 72 h. Experimental results suggest that a high Fe/As ratio was necessary, so that the excess iron promotes the formation a product of good stability, arsenical ferrihydrite (AsFH: AsO43−·Fe(OH)(H2O)1+x) under a relatively high pH in acidic solution.

Relationship between Positive Environmental Disclosures and Environmental Performance: An Empirical Investigation of the Greenwashing Sin of the Hidden Trade‐off

SummaryFirms make positive discretionary disclosures about their environmental efforts in order to signify attention to the environmental impacts of their operations. On the one hand, firms may choose to make these disclosures to deflect attention away from other activities that may contribute negatively to their environmental performance (i.e., greenwashing in the form of the “sin of the hidden trade‐off ”). On the other hand, firms making these disclosures may legitimately improve their overall environmental performance. Our study empirically addresses the following question: Do firms that make positive discretionary environmental disclosures improve their overall environmental performance more than the firms that do not make such disclosures? Specifically, because press announcements have been shown to be a popular medium for positive discretionary disclosures, we examine the relationship between announcements in the press of firms’ environmental efforts beyond compliance, and suitably weighted‐aggregated firm‐level releases of the range of pollutants reported to the U.S. Environmental Protection Agency's Toxics Release Inventory (TRI). We employ matching methods (coarsened exact matching and propensity score matching) that account for potential sources of endogeneity, including the relationship between firms’ prior environmental performance and their propensity to disclose environmental information. Our findings from the matching methods provide encouraging evidence that greenwashing in the form of the sin of the hidden trade‐off does not appear to be prevalent. Additionally, our post hoc analysis explores factors based on the content of disclosures and industry, that may help explain differences in environmental performance among the firms making the disclosures.