Performance of an in situ activated carbon treatment to reduce PCB availability in an active harbor

In situ amendment of surface sediment with activated carbon is a promising technique for reducing the availability of hydrophobic organic compounds in surface sediment. The present study evaluated the performance of a logistically challenging activated carbon placement in a high-energy hydrodynamic environment adjacent to and beneath a pier in an active military harbor. Measurements conducted preamendment and 10, 21, and 33 months (mo) postamendment using in situ exposures of benthic invertebrates and passive samplers indicated that the targeted 4% (by weight) addition of activated carbon (particle diameter ≤74 µm) in the uppermost 10 cm of surface sediment reduced polychlorinated biphenyl availability by an average (± standard deviation) of 81 ± 11% in the first 10 mo after amendment. The final monitoring event (33 mo after amendment) indicated an approximate 90 ± 6% reduction in availability, reflecting a slight increase in performance and showing the stability of the amendment. Benthic invertebrate census and sediment profile imagery did not indicate significant differences in benthic community ecological metrics among the preamendment and 3 postamendment monitoring events, supporting existing scientific literature that this approximate activated carbon dosage level does not significantly impair native benthic invertebrate communities. Recommendations for optimizing typical site-specific assessments of activated carbon performance are also discussed and include quantifying reductions in availability and confirming placement of activated carbon. Environ Toxicol Chem 2018;37:1767-1777. Published 2018 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

Ecological Risk Analysis for Benzalkonium Chloride, Benzethonium Chloride, and Chloroxylenol in US Disinfecting and Sanitizing Products

Use of three topical antiseptic compounds-benzalkonium chloride (BAC), benzethonium chloride (BZT), and chloroxylenol (PCMX)-has recently increased because of the phaseout of other antimicrobial ingredients (such as triclosan) in soaps and other disinfecting and sanitizing products. Further, use of sanitizing products in general increased during the coronavirus (COVID-19) pandemic. We assessed the environmental safety of BAC, BZT, and PCMX based on best available environmental fate and effects data from the scientific literature and privately held sources. The ecological exposure assessment focused on aquatic systems receiving effluent from wastewater-treatment plants (WWTPs) and terrestrial systems receiving land-applied WWTP biosolids. Recent exposure levels were characterized based on environmental monitoring data supplemented by modeling, while future exposures were modeled based on a hypothetical triclosan replacement scenario. Hazard profiles were developed based on acute and chronic studies examining toxicity to aquatic life (fish, invertebrates, algae, vascular plants) and terrestrial endpoints (plants, soil invertebrates, and microbial functions related to soil fertility). Risks to higher trophic levels were not assessed because these compounds are not appreciably bioaccumulative. The risk analysis indicated that neither BZT nor PCMX in any exposure media is likely to cause adverse ecological effects under the exposure scenarios assessed in the present study. Under these scenarios, total BAC exposures are at least three times less than estimated effect thresholds, while margins of safety for freely dissolved BAC are estimated to be greater than an order of magnitude. Because the modeling did not specifically account for COVID-19 pandemic-related usage, further environmental monitoring is anticipated to understand potential changes in environmental exposures as a result of increased antiseptic use. The analysis presented provides a framework to interpret future antiseptic monitoring results, including monitoring parameters and modeling approaches to address bioavailability of the chemicals of interest. Environ Toxicol Chem 2022;41:3095-3115. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Target Lipid Model and Empirical Organic Carbon Partition Coefficients Predict Sediment Toxicity of Polychlorinated Biphenyls to Benthic Invertebrates

Quantifying causal exposure-response relationships for polychlorinated biphenyl (PCB) toxicity to benthic invertebrates can be an important component of contaminated sediment assessments, informing cleanup decisions and natural resource injury determinations. Building on prior analyses, we demonstrate that the target lipid model accurately predicts aquatic toxicity of PCBs to invertebrates, providing a means to account for effects of PCB mixture composition on the toxicity of bioavailable PCBs. We also incorporate updated data on PCB partitioning between particles and interstitial water in field-collected sediments, to better account for effects of PCB mixture composition on PCB bioavailability. To validate the resulting model, we compare its predictions with sediment toxicity data from spiked sediment toxicity tests and a variety of recent case studies from sites where PCBs are the primary sediment contaminant. The updated model should provide a useful tool for both screening-level and in-depth risk analyses for PCBs in sediment, and it should aid in diagnosing potential contributing factors at sites where sediment toxicity and benthic community impairment are observed. Environ Toxicol Chem 2023;42:1134-1151. © 2023 SETAC.

Bisphenol A in German watersheds: Part II. FlowEQ model-based characterization of sources and current and future conditions

Increasing scientific and regulatory concern regarding environmental concentrations of bisphenol A (BPA) increases the need to understand the sources and sinks of this chemical. We developed a coupled flow network/fugacity-based fate and transport model to assess the contribution of different emissions sources to the concentration of BPA in surface water in Germany. The model utilizes BPA loadings and sinks, BPA physicochemical properties, a water flow network, environmental characteristics, and fugacity equations. The model considers industrial emissions, leaching from BPA-containing articles, wastewater treatment and bypass events, and emissions from landfills. The model also considers different scenarios that account for changes in the usage profile of BPA. Model predictions compare favorably to measured surface water concentrations, with the modeled concentrations generally falling within the range of measured values. Model scenarios that consider reductions in BPA usage due to government-mandated restrictions and voluntary reductions in usage predict falling BPA concentrations that are consistent with the most recent monitoring data. Model predictions of the contributions from different usage scenarios and wastewater treatment methods can be used to assess the efficacy of different restrictions and waste handling strategies to support efforts to evaluate the costs and benefits associated with actions aimed at reducing BPA levels in the environment. This feature of the model is of particular importance, given current efforts to update the regulations regarding BPA usage in the EU. The model indicates that as the current restriction on BPA in thermal paper works through the paper recycling process, BPA concentrations will continue to decrease. Other actions, such as upgrades to the stormwater and wastewater infrastructure to minimize the frequency of storm-related bypasses, are predicted to provide more meaningful reductions than additional restrictions on usage. Integr Environ Assess Manag 2024;20:226-238. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Bisphenol A in surface waters in Germany: Part I. Reassessment of sources and emissions pathways for FlowEQ modeling

Bisphenol A (BPA) enters the environment through various industrial and consumer-related pathways. Industrial sources include BPA manufacturing and secondary industrial uses such as the manufacturing of polymers and other substances based on or containing BPA. However, secondary sources and emissions to the environment, such as those related to the consumer use of articles containing BPA, may be more important than industrial emissions. Although readily biodegradable, BPA is widely distributed in various environmental compartments and living organisms. It is still not well understood which specific sources and pathways are responsible for releasing BPA into the environment. Therefore, we developed FlowEQ, a coupled flow network and fugacity-based fate and transport model for the assessment of BPA in surface water. The work is divided into two parts. In Part I, inputs needed to support the modeling and model validation were collected. Bisphenol A was measured at 23 wastewater treatment plants (WWTPs) and 21 landfills in Germany. In addition, the BPA content of 132 consumer articles from 27 article classes was analyzed. Bisphenol A concentrations in WWTPs ranged from 0.33 to 910 µg L-1 in influents and from less than 0.01 to 0.65 µg L-1 in effluents, resulting in removal efficiencies of 13%-100%. Average BPA concentrations in landfill leachate ranged from less than 0.01 to approximately 1400 µg L-1 . Bisphenol A concentrations measured in consumer articles varied significantly by type, ranging from less than 0.5 µg kg-1 in printing inks up to 1 691 700 µg kg-1 in articles made from recycled polyvinyl chloride (PVC). These concentrations were combined with information on use, leaching, and contact with water to develop estimates of loadings. Together with the results of the FlowEQ modeling presented in Part II, this assessment improves our understanding of the sources and emission pathways of BPA in surface water. The model considers various sources of BPA and can estimate future surface water concentrations of BPA based on changes in use. Integr Environ Assess Manag 2024;20:211-225. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).