Science-informed Policy Making for Protecting People and the Environment from Radiation

ABSTRACT

The process to arrive at the radiation protection practices of today to protect workers, patients, and the public, including sensitive populations, has been a long and deliberative one. This paper presents an overview of the US Environmental Protection Agency's (US EPA) responsibility in protecting human health and the environment from unnecessary exposure to radiation. The origins of this responsibility can be traced back to early efforts, a century ago, to protect workers from x rays and radium. The system of radiation protection we employ today is robust and informed by the latest scientific consensus. It has helped reduce or eliminate unnecessary exposures to workers, patients, and the public while enabling the safe and beneficial uses of radiation and radioactive material in diverse areas such as energy, medicine, research, and space exploration. Periodic reviews and analyses of research on health effects of radiation by scientific bodies such as the National Academy of Sciences, National Council on Radiation Protection and Measurements, United Nations Scientific Committee on the Effects of Atomic Radiation, and the International Commission on Radiological Protection continue to inform radiation protection practices while new scientific information is gathered. As a public health agency, US EPA is keenly interested in research findings that can better elucidate the effects of exposure to low doses and low dose rates of radiation as applicable to protection of diverse populations from various sources of exposure. Professional organizations such as the Health Physics Society can provide radiation protection practitioners with continuing education programs on the state of the science and describe the key underpinnings of the system of radiological protection. Such efforts will help equip and prepare radiation protection professionals to more effectively communicate radiation health information with their stakeholders.

Per- and Polyfluoroalkyl Substance Exposure Risks in US Carceral Facilities, 2022

Objectives. To assess the US incarcerated population's risk of exposure to per- and polyfluoroalkyl substances (PFASs). Methods. We assessed how many of the 6118 US carceral facilities were located in the same hydrologic unit code watershed boundaries as known or likely locations of PFAS contamination. We conducted geospatial analyses on data aggregated from Environmental Protection Agency databases and a PFAS site tracker in 2022 to model the hydrologically feasible known and presumptive PFAS contamination sites for nearly 2 million incarcerated people. Results. Findings indicate that 5% (∼310) of US carceral facilities have at least 1 known source of PFAS contamination in the same watershed boundary and that it is at a higher elevation than the facility; also 47% (∼2285) have at least 1 presumptive source. A minimum of 990 000 people are incarcerated in these facilities, including at least 12 800 juveniles. Exposure risks faced by incarcerated youths are disproportionately underassessed. Conclusions. The long-term impacts from potential exposures to PFAS are preventable and exacerbate health inequities among incarcerated populations. Widespread public attention to PFASs can be parlayed into broader environmental monitoring for imprisoned people. (Am J Public Health. 2024;114(5):501-510. https://doi.org/10.2105/AJPH.2024.307571).

Systematic Approaches for the Encoding of Chemical Groups: A Case Study

Regulatory authorities aim to organize substances into groups to facilitate prioritization within hazard and risk assessment processes. Often, such chemical groupings are not explicitly defined by structural rules or physicochemical property information. This is largely due to how these groupings are developed, namely, a manual expert curation process, which in turn makes updating and refining groupings, as new substances are evaluated, a practical challenge. Herein, machine learning methods were leveraged to build models that could preliminarily assign substances to predefined groups. A set of 86 groupings containing 2,184 substances as published on the European Chemicals Agency (ECHA) website were mapped to the U.S. Environmental Protection Agency (EPA) Distributed Toxicity Structure Database (DSSTox) content to extract chemical and structural information. Substances were represented using Morgan fingerprints, and two machine learning approaches were used to classify test substances into 56 groups containing at least 10 substances with a structural representation in the data set: k-nearest neighbor (kNN) and random forest (RF), that led to mean 5-fold cross-validation test accuracies (average F1 scores) of 0.781 and 0.853, respectively. With a 9% improvement, the RF classifier was significantly more accurate than KNN (p-value = 0.001). The approach offers promise as a means of the initial profiling of new substances into predefined groups to facilitate prioritization efforts and streamline the assessment of new substances when earlier groupings are available. The algorithm to fit and use these models has been made available in the accompanying repository, thereby enabling both use of the produced models and refitting of these models, as new groupings become available by regulatory authorities or industry.

Public Health Relevance of US EPA Air Quality Index Activity Recommendations

Importance

Reducing exposure to fine particulate matter (<2.5 μm [PM2.5]) air pollution improves cardiopulmonary morbidity and mortality. However, the public health relevance of air quality index (AQI) activity guidelines under present-day environmental conditions in the US has not been critically assessed.

Objective

To evaluate the public health relevance of following PM2.5 AQI activity guidance in preventing serious atherosclerotic cardiovascular disease (ASCVD) and pulmonary events among adults in the US.

Design, Setting, and Participants

This cross-sectional modeling study involved the general adult population and sensitive individuals as designated by the US Environmental Protection Agency (EPA), including adults with preexisting ASCVD or lung disease (asthma or chronic obstructive pulmonary disease). The study was conducted between August 1, 2023, and January 31, 2024.

Exposures

Daily AQI strata for PM2.5 and the corresponding activity recommendations.

Main Outcomes and Measures

The main outcome was the number needed to treat (NNT) per day by following activity guidance across daily AQI strata to prevent 1 serious ASCVD or pulmonary event among relevant populations. To calculate PM2.5-induced excess disease event rates per day, estimated baseline disease-specific daily event rates for each group were multiplied by the increase in risks due to PM2.5 levels at each AQI stratum. The number of events prevented per day was calculated by multiplying each excess disease event rate by the percentage in exposure reduction plausibly incurred by following population-specific activity guidance at each AQI level. The NNT is the reciprocal of the number of events prevented.

Results

The NNT to prevent ASCVD events was high for the general population and for patients with ASCVD across all AQI strata. The range of values was comparatively lower to prevent pulmonary events among adults with lung disease. During most days (96%) when activity recommendations were promulgated due to elevated PM2.5 (AQI, 101-200), the NNT to prevent a serious disease event remained very high for the general population (>18 million), patients with ASCVD (approximately 1.6-5 million), and adults with lung disease (approximately 66 000-202 000).

Conclusions and Relevance

These findings suggest that existing PM2.5 AQI activity recommendations are of questionable public health relevance in present-day conditions and merit consideration for updating to improve their potential effectiveness.

Evaluation of Appropriate Conditions for Efficient Simultaneous Determination of US EPA and EU Priority Polycyclic Aromatic Hydrocarbons in Various Food Categories and Assessment of Their Consumption Risk

The QuEChERS (quick, easy, cheap, effective, rugged and safe) conditions were optimized for efficient determination of the U.S. Environmental Protection Agency (US EPA) and European Union (EU) priority polycyclic aromatic hydrocarbons (PAHs) for the categories of grains, tuber & starchy vegetables, soy beans and products, fish & seafood, and poultry & meat, including raw materials and their corresponding products. The PAHs were analyzed using ultrahigh-performance liquid chromatography with temperature-controlled fluorescence detection and gas chromatography with tandem mass spectrometry. The established conditions had good accuracy, repeatability, and precision. Environmental pollution and processing methods influence the level of PAHs in samples. The low molecular weight PAHs were present in all raw materials, and processing increased high and low molecular weight PAHs in the products. The excess cancer risk for consumption of PAHs in cooked samples was mostly acceptable; a small number of samples might be of slight concern in certain age groups.

Expanded Systematic Evidence Map for Hundreds of Per- and Polyfluoroalkyl Substances (PFAS) and Comprehensive PFAS Human Health Dashboard

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) encompass a class of chemically and structurally diverse compounds that are extensively used in industry and detected in the environment. The US Environmental Protection Agency (US EPA) 2021 PFAS Strategic Roadmap describes national research plans to address the challenge of PFAS.

OBJECTIVES

Systematic Evidence Map (SEM) methods were used to survey and summarize available epidemiological and mammalian bioassay evidence that could inform human health hazard identification for a set of 345 PFAS that were identified by the US EPA's Center for Computational Toxicology and Exposure (CCTE) for in vitro toxicity and toxicokinetic assay testing and through interagency discussions on PFAS of interest. This work builds from the 2022 evidence map that collated evidence on a separate set of ∼ 150 PFAS. Like our previous work, this SEM does not include PFAS that are the subject of ongoing or completed assessments at the US EPA.

METHODS

SEM methods were used to search, screen, and inventory mammalian bioassay and epidemiological literature from peer-reviewed and gray literature sources using manual review and machine-learning software. For each included study, study design details and health end points examined were summarized in interactive web-based literature inventories. Some included studies also underwent study evaluation and detailed extraction of health end point data. All underlying data is publicly available online as interactive visuals with downloadable metadata.

RESULTS

More than 13,000 studies were identified from scientific databases. Screening processes identified 121 mammalian bioassay and 111 epidemiological studies that met screening criteria. Epidemiological evidence (available for 12 PFAS) mostly assessed the reproductive, endocrine, developmental, metabolic, cardiovascular, and immune systems. Mammalian bioassay evidence (available for 30 PFAS) commonly assessed effects in the reproductive, whole-body, nervous, and hepatic systems. Overall, 41 PFAS had evidence across mammalian bioassay and epidemiology data streams (roughly 11% of searched chemicals).

DISCUSSION

No epidemiological and/or mammalian bioassay evidence were identified for most of the PFAS included in our search. Results from this SEM, our 2022 SEM on ∼ 150 PFAS, and other PFAS assessment products from the US EPA are compiled into a comprehensive PFAS dashboard that provides researchers and regulators an overview of the current PFAS human health landscape including data gaps and can serve as a scoping tool to facilitate prioritization of PFAS-related research and/or risk assessment activities. https://doi.org/10.1289/EHP13423.

EPA scraps plan to end all testing in mammals by 2035

U.S. environmental agency's hard deadline had split scientific community.

The Role of Emission Size Distribution on the Efficacy of New Technologies to Reduce Methane Emissions from the Oil and Gas Sector

Methane emissions from oil and gas operations exhibit skewed distributions. New technologies such as aerial-based leak detection surveys promise cost-effective detection of large emitters (greater than 10 kg/h). Recent policies such as the US Environmental Protection Agency (EPA) methane rule that allow the use of new technologies as part of leak detection and repair (LDAR) programs require a demonstration of equivalence with existing optical gas imaging (OGI) based LDAR programs. In this work, we illustrate the impact of emission size distribution on the equivalency condition between the OGI and site-wide survey technologies. Emission size distributions compiled from aerial measurements include significantly more emitters between 1 and 10 kg/h and lower average emission rates for large emitters compared to the emission distribution in the EPA rule. As a result, we find that equivalence may be achieved at lower site-wide survey frequencies when using technologies with detection thresholds below 10 kg/h, compared to the EPA rule. However, equivalence cannot be achieved with a detection threshold of 30 kg/h at any survey frequency, because most emitters across most US basins exhibit emission rates below 30 kg/h. We find that equivalence is a complex tradeoff among technology choice, design of LDAR programs, and survey frequency that can have more than one unique solution set.

Corporate ESG performance when neighboring the Environmental Protection Agency

Practicing ESG concept is a necessary way for sustainable development of enterprises and an important hand in realizing high-quality economic growth. This paper introduces the hypothesis of "distance attenuation effect" of geo-economics into the research field of corporate ESG performance, and systematically examines the impact of neighboring the Environmental Protection Agency (EPA) on corporate ESG performance by using the data of China's listed companies in the manufacturing industry from 2011 to 2021. It is found that being a neighbor to the EPA has a significant inhibitory effect on corporate ESG performance, which was reduced by 0.196% when the distance between the two was reduced by every 1 km. And the inhibitory effect has a stepwise decreasing characteristic, i.e., it is the strongest at the level of county EPA, followed by municipal EPA, and the smallest at the level of provincial EPA. The mechanism analysis shows that the rent-seeking behavior caused by neighboring with EPA is an important reason for the decline of ESG performance, which verifies the "distance attenuation effect" of rent-seeking difficulty. Although neighboring the EPA improves firms' financial performance, it greatly harms firms' environmental, social and governance performance, which confirms the profit-seeking motive of firms' rent-seeking. In addition, the deterrent effect generated by third-party supervision and digital supervision can inhibit corporate rent-seeking to a certain extent, which helps weaken the negative impact of neighboring the EPA on corporate ESG performance.

Superfund Sites and the Bipartisan Infrastructure Law in New Jersey State: A Photo Essay

In 2021, the Infrastructure Investment and Jobs Act, also known as the Bipartisan Infrastructure Law (BIL), became law, with one component being an investment to clean-up Superfund and Brownfield sites. Through BIL funding, the Environmental Protection Agency announced $3.5 billion to clean-up Superfund sites that have been awaiting funding for years in mostly historically underserved communities. As in many states, the 3 Superfund sites used as examples in this essay are in a metropolitan or surrounding area and in residential communities. The photos in this essay help highlight how hazardous waste sites have come to look like normal industrial sites and that communities are often unaware of the dangerous exposures they face. The author suggests that in the age of social media, taking pictures and documentation of hazardous waste sites today in our communities can help mobilize public awareness and drive action to be taken toward delayed clean-up.

Methylene Chloride Comment

Last May 2023, the U.S. Environmental Protection Agency (EPA) published a proposed rule to restrict the production and use of a dangerous chemical called methylene chloride pursuant to its authority under the Toxic Substance Control Act-the first such measure since Congress significantly overhauled that law in 2016. Methylene chloride presents a variety of health and safety risks, particularly for workers in industries in which the chemical is still widely used. In support of the proposed rule, the EPA prepared a document called a cost-benefit analysis, which purports to evaluate the rule by calculating its net benefits-that is, the rule's likely benefits over and above its likely costs. Cost-benefit analysis has been the subject of substantial criticism in recent decades, and the Biden administration is pursuing significant reforms for how these analyses are performed. Together with my colleague Dr. Federico Holm, I submitted comments to the EPA criticizing the cost-benefit analysis for the proposed methylene chloride rule. In these comments, we criticize the agency for continuing to employ an overly formalistic approach to cost-benefit analysis, which both systematically undervalues the benefits of regulations and ignores impact issues like worker justice. We also criticize several specific aspects of the agency's analytical methodology, including its failure to follow the proposed reforms now being developed by the Biden administration.

A Gridded Inventory of Annual 2012-2018 U.S. Anthropogenic Methane Emissions

Nationally reported greenhouse gas inventories are a core component of the Paris Agreement's transparency framework. Comparisons with emission estimates derived from atmospheric observations help identify improvements to reduce uncertainties and increase the confidence in reported values. To facilitate comparisons over the contiguous United States, we present a 0.1° × 0.1° gridded inventory of annual 2012-2018 anthropogenic methane emissions, allocated to 26 individual source categories, with scale-dependent error estimates. Our inventory is consistent with the U.S. Environmental Protection Agency (EPA) Inventory of U.S. Greenhouse Gas Emissions and Sinks (GHGI), submitted to the United Nations in 2020. Total emissions and patterns (spatial/temporal) reflect the activity and emission factor data underlying the GHGI, including many updates relative to a previous gridded version of the GHGI that has been extensively compared with observations. These underlying data are not generally available in global gridded inventories, and comparison to EDGAR version 6 shows large spatial differences, particularly for the oil and gas sectors. We also find strong regional variability across all sources in annual 2012-2018 spatial trends, highlighting the importance of understanding regional- and facility-level activities. Our inventory represents the first time series of gridded GHGI methane emissions and enables robust comparisons of emissions and their trends with atmospheric observations.

Assessing utility of thyroid in vitro screening assays through comparisons to observed impacts in vivo

To better understand endocrine disruption, the U.S. Environmental Protection Agency's (USEPA) Endocrine Disruptor Screening Program (EDSP) utilizes a two-tiered approach to investigate the potential of a chemical to interact with the estrogen, androgen, or thyroid systems. As in vivo testing lacks the throughput to address data gaps on endocrine bioactivity for thousands of chemicals, in vitro high-throughput screening (HTS) methods are being developed to screen larger chemical libraries. The primary objective of this work was to investigate for how many of the 52 chemicals with weight-of-evidence (WoE) determinations from EDSP Tier 1 screening there are available in vitro HTS data supporting a thyroid impact. HTS data from the USEPA ToxCast program and the EDSP WoE were collected for this analysis. Considering the complexity of endocrine disruption and interpreting HTS data, concordance between in vitro activity and in vivo effects ranges from 58 to 78%. Based on this evaluation, we conclude that the current suite of HTS assays is beneficial for prioritizing chemicals for further inquiry; however, without a more detailed analysis, one cannot conclude whether HTS results are the primary mode-of-action. Furthermore, development of in vitro assays for additional thyroid-relevant molecular initiating events is required to effectively predict in vivo thyroid impacts.

Evaluating PM2.5 element concentration measurements for a nationwide monitoring network

Particulate matter (PM) concentrations have decreased dramatically over the past 20 years, thus lower method detection limits (MDL) are required for these measurements. Energy-dispersive X-ray fluorescence (XRF) spectroscopy is used to quantify multiple elements simultaneously in the U.S. Environmental Protection Agency (EPA) Chemical Speciation Network (CSN). Inductively-coupled plasma mass spectrometry (ICP-MS) is an alternative analysis with lower MDL for elements. Here, we present a side-by-side comparison of XRF and ICP-MS for elements in PM2.5 samples collected via the EPA's CSN. For ICP-MS, a simple extraction and ICP-MS analysis technique was applied to a wide variety of samples to minimize effort and cost and serve as a feasibility test for a large monitoring network. Filter samples (N = 549) from various urban locations across the US were analyzed first analyzed via XRF at UC Davis and then ICP-MS at RTI International. Both methods measured 29 of the same elements out of the 33 usually reported to CSN. Of these 29, 14 elements (Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb) were found to be frequently detected (i.e. had more than 10% of values above both XRF and ICP-MS MDL). ICP-MS was found to have lower MDL for 26 out of 29 elements, namely Na, Mg, Al, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, As, Se, Rb, Sr, Zr, Ag, Cd, In, Sn, Sb, Cs, Ba, Ce, Pb; conversely, XRF had lower MDL for 3 elements, namely, P, K, Zn. Intra-method quality checks using (1) inter-elemental inspection of scatter plots using a priori knowledge of element sources and (2) scatter plots of routine versus collocated measurements reveal that ICP-MS exhibits better measurement precision. Lower detection limits for element measurements in nationwide PM monitoring networks would benefit human-health and source apportionment research.Implications: We demonstrate that ICP-MS with adilute-acid digestion method would significantly improve the element detection rates and thus be avaluable addition to the current analysis techniques for airborne PM samples in anationwide monitoring network. In this paper, we show that a hybrid method of elemental analysis for airborne particulate matter (PM) would significantly improve the detection rates for elements in PM. This would be a valuable addition to the current analysis techniques for airborne PM samples in nationwide and other large-scale monitoring networks, such as the EPA's Chemical Speciation Network (CSN). The techniques explored in this study (i.e., X-ray Fluorescence Spectroscopy or XRF and Inductively Coupled Plasma-Mass Spectrometry or ICP-MS) are relevant to the PM monitoring and regulatory community audience of JAWMA, especially agencies and states that are already involved in CSN. In addition, our results outline considerations that give insight on factors to consider for other large-scale and long-term ambient air monitoring efforts.

Nonpoint source pollution measures in the Clean Water Act have no detectable impact on decadal trends in nutrient concentrations in U.S. inland waters

The Clean Water Act (CWA) of 1972 regulates water quality in U.S. inland waters under a system of cooperative federalism in which states are delegated implementation and enforcement authority of CWA provisions by the U.S. Environmental Protection Agency. We leveraged heterogeneity in state implementation of the CWA to evaluate the efficacy of its nonpoint source provisions in reducing nutrient pollution, the leading cause of water quality impairment in U.S. inland waters. We used national survey data to estimate changes in nutrient concentrations over a decade and evaluated the effect of state-level policy implementation. We found no evidence to support an effect of (i) grant spending on nonpoint source pollution remediation, (ii) nutrient criteria development, or (iii) water quality monitoring intensity on 10-year trends in nutrient concentrations. These results suggest that the current federal policy paradigm for improving water quality is not creating desired outcomes.

Stigma as a multispatial-scale process: Revisiting the worst US Superfund sites

Areas immediately adjacent to 16 of the first US national priority (NPL) hazardous waste sites that also had pre-superfund emergency actions were examined to measure local stigma. Four decades after their NPL designation, I found marked variation in these areas' social, public health and environmental attributes. About one-third of these small areas fit the stereotype of stressed areas with environmental injustice challenges. Yet, another one-third of these sites have better measurable outcomes than a combination of their host states and counties. For example, they have elevated levels of broadband access and their local jurisdictions are classified as safe and attractive to families. I conclude that long-term stigma around a Superfund site was limited by US EPA actions, as well as by progressive state and local governments, and community groups, in other words, contributions from parties at multiple geographical scales.

Cutting-edge computational chemical exposure research at the U.S. Environmental Protection Agency

Exposure science is evolving from its traditional "after the fact" and "one chemical at a time" approach to forecasting chemical exposures rapidly enough to keep pace with the constantly expanding landscape of chemicals and exposures. In this article, we provide an overview of the approaches, accomplishments, and plans for advancing computational exposure science within the U.S. Environmental Protection Agency's Office of Research and Development (EPA/ORD). First, to characterize the universe of chemicals in commerce and the environment, a carefully curated, web-accessible chemical resource has been created. This DSSTox database unambiguously identifies >1.2 million unique substances reflecting potential environmental and human exposures and includes computationally accessible links to each compound's corresponding data resources. Next, EPA is developing, applying, and evaluating predictive exposure models. These models increasingly rely on data, computational tools like quantitative structure activity relationship (QSAR) models, and machine learning/artificial intelligence to provide timely and efficient prediction of chemical exposure (and associated uncertainty) for thousands of chemicals at a time. Integral to this modeling effort, EPA is developing data resources across the exposure continuum that includes application of high-resolution mass spectrometry (HRMS) non-targeted analysis (NTA) methods providing measurement capability at scale with the number of chemicals in commerce. These research efforts are integrated and well-tailored to support population exposure assessment to prioritize chemicals for exposure as a critical input to risk management. In addition, the exposure forecasts will allow a wide variety of stakeholders to explore sustainable initiatives like green chemistry to achieve economic, social, and environmental prosperity and protection of future generations.

Weight of evidence for cross-species conservation of androgen receptor-based biological activity

The U.S. Environmental Protection Agency's Endocrine Disruptor Screening Program (EDSP) is tasked with assessing chemicals for their potential to perturb endocrine pathways, including those controlled by androgen receptor (AR). To address challenges associated with traditional testing strategies, EDSP is considering in vitro high-throughput screening assays to screen and prioritize chemicals more efficiently. The ability of these assays to accurately reflect chemical interactions in nonmammalian species remains uncertain. Therefore, a goal of the EDSP is to evaluate how broadly results can be extrapolated across taxa. To assess the cross-species conservation of AR-modulated pathways, computational analyses and systematic literature review approaches were used to conduct a comprehensive analysis of existing in silico, in vitro, and in vivo data. First, molecular target conservation was assessed across 585 diverse species based on the structural similarity of ARs. These results indicate that ARs are conserved across vertebrates and are predicted to share similarly susceptibility to chemicals that interact with the human AR. Systematic analysis of over 5000 published manuscripts was used to compile in vitro and in vivo cross-species toxicity data. Assessment of in vitro data indicates conservation of responses occurs across vertebrate ARs, with potential differences in sensitivity. Similarly, in vivo data indicate strong conservation of the AR signaling pathways across vertebrate species, although sensitivity may vary. Overall, this study demonstrates a framework for utilizing bioinformatics and existing data to build weight of evidence for cross-species extrapolation and provides a technical basis for extrapolating hAR-based data to prioritize hazard in nonmammalian vertebrate species.

Utility of an alternative method (to USEPA Method 1613) for analysis of priority persistent organic pollutants in soil from mixed industrial-suburban areas of Durban, South Africa

This study evaluates the adequacy of a USEPA Method 1613 alternative analytical method for analysis of persistent organic pollutants (POPs) in soil from the immediate vicinity of industrialized areas in the eThekwini municipal area in South Africa. The objective of this study is in line with the Stockholm Convention Article 11 on research, development, and monitoring. Furthermore, it became imperative to find an alternative analytical procedure to USEPA Method 1613 that could cater to studies conducted in Africa where recent reviews have indicated that most African countries lack the technical and instrumental capacity for performing analysis of dioxin-like compounds according to USEPA Method 1613, which entails the use of high-resolution chromatography and high-resolution mass spectrometry instrumentation. The study aimed to ascertain the utility of an alternative two-dimensional gas chromatography-time of flight mass spectrometry method for analysis of trace-level priority POPs in soil, along with a fast single quadrupole gas chromatography-mass spectrometry method. The analytical methods were applied to the analysis of POPs on soil samples from industrial areas with oil refineries and a pulp and paper manufacturing company, while other samples were collected near the electricity substations and a landfill site. Analytical results showed BDE 209 as the dominant contaminating polybrominated diphenyl ether (concentration ranges from 0.006 to 5.71 ng g^-1 ). Polybrominated biphenyls (PBBs) 9, 10, and 49 were the dominant PBBs detected in 78% of the sites tested, although their concentrations were below the limit of quantification (LOQ). Polychlorinated dibenzo-p-dioxins and furans and dioxin-like polychlorinated biphenyls detected could not be quantified above their respective LOQs, indicating that the Durban area has low priority pollutant contamination levels compared to other regions around the world. The methods developed are a starting point that will inform considerations for routine evaluation and management of soil contamination, which plays a vital role in environmental management. Integr Environ Assess Manag 2023;19:749-762. © 2022 SETAC.

Methods to Account for CAP-88 PC-Omitted Nuclides in Radioactive Air Emissions From DOE Facilities

ABSTRACT

Routine research and development activities at US Department of Energy facilities can result in the release of radioactive emissions, potentially exposing the public and the environment. Such emissions are subject to certain Clean Air Act regulations, specifically those outlined in 40 CFR Part 61, Subpart H, which are enforced by the US Environmental Protection Agency. Compliance is determined in part with a dose standard. Doses to members of the public from most US Department of Energy facility airborne emissions are modeled using CAP-88 PC software, the latest version of which contains more than 1,200 radionuclides. Radioactive effluents from US Department of Energy facilities may contain radioisotopes that are not available in CAP-88 PC, and those radioisotopes must still be evaluated to determine whether doses to members of the public are below established limits. CAP-88 PC-omitted radionuclides can be accounted for using alternate methods, including the use of surrogate radionuclides. This paper elucidates the process of accounting for CAP-88 PC-omitted radionuclides by providing criteria and rationale for surrogate selection, a compilation of surrogate radionuclides used in the past by US Department of Energy facilities, a discussion of alternate methods used to account for CAP-88 PC-omitted radionuclides and a comparison of methods and impacts on receptor doses. Ultimately, this paper aims to aid in the process of surrogate selection and consequently to simplify and expedite compliance with Clean Air Act regulations.

Is the 90-day dog study necessary for pesticide toxicity testing?

When registering a new pesticide, 90-day oral toxicity studies performed with both rodent and non-rodent species, typically rats and dogs, are part of a standard battery of animal tests required in most countries for human health risk assessment (RA). This analysis set out to determine the need for the 90-day dog study in RA by reviewing data from 195 pesticides evaluated by the US Environmental Protection Agency (USEPA) from 1998 through 2021. The dog study was used in RA for only 42 pesticides, mostly to set the point of departure (POD) for shorter-term non-dietary pesticide exposures. Dog no-observed-adverse-effect-levels (NOAELs) were lower than rat NOAELs in 90-day studies for 36 of the above 42 pesticides, suggesting that the dog was the more sensitive species. However, lower NOAELs may not necessarily correspond to greater sensitivity as factors such as dose spacing and/or allometric scaling need to be considered. Normalizing doses between rats and dogs explained the lower NOAELs in 22/36 pesticides, indicating that in those cases the dog was not more sensitive, and the comparable rat study could have been used instead for RA. For five of the remaining pesticides, other studies of appropriate duration besides the 90-day rat study were available that would have offered a similar level of protection if used to set PODs. In only nine cases could no alternative be found in the pesticide's database to use in place of the 90-day dog study for setting safe exposure levels or to identify unique hazards. The present analysis demonstrates that for most pesticide risk determinations the 90-day dog study provided no benefit beyond the rat or other available data.

Evaluation of the integrated exposure uptake biokinetic (IEUBK) model for lead in children

BACKGROUND

The Integrated Exposure Uptake Biokinetic Model for Lead in Children (IEUBK model) was developed by the U.S. Environmental Protection Agency to support assessments of health risks to children from exposures to lead (Pb).

OBJECTIVE

This study evaluated performance of IEUBK model (v2.0) as it would be typically applied at Superfund sites to predict blood Pb levels (BLLs) in populations of children.

METHODS

The model was evaluated by comparing model predictions of BLLs to 1144 observed BLLs in a population of children at the Bunker Hill Superfund Site for which there were paired estimates of environmental Pb concentrations.

RESULTS

Predicted population geometric mean (GM) BLLs (GM: 3.4 µg/dL, 95% CI: 3.3, 3.5) were within 0.3 µg/dL of observed (GM: 3.6 µg/dL, 95% CI: 3.5, 3.8). The model predicted the observed age trend in GM BLLs and explained ~90% of the variance in the observed age-stratified GM BLLs. The mean predicted probability of exceeding 5 µg/dL (P5) was 27% (95% CI: 24, 29) and observed P5 was 32% (95% CI: 29, 35), a difference of 5%. Differences between geographic area stratified mean P5 (predicted minus observed) ranged from -11 to 14% (mean difference: 2.3%).

SIGNIFICANCE

Although the more general applicability of these findings to other populations remains to be determined in future studies, our results support applications of the IEUBK model (v2.0) for informing risk-based decisions regarding remediation of soils and mitigation of exposures at Superfund sites where the majority of the exposure unit GM BLLs are expected to be ≤5 µg/dL and where it is desired to limit the predicted probability of exceeding 5 µg/dL to <5%.

Ambient water quality criteria derived using probabilistic risk assessment

National recommendations for numeric human health ambient water quality criteria (AWQC) for toxic substances are derived by the US Environmental Protection Agency (USEPA) using a deterministic approach that combines point estimates for exposure, toxicity, and acceptable risk. In accordance with the Clean Water Act, states, territories, and authorized tribes must either adopt these recommendations or modify and replace them with criteria using an alternative, scientifically defensible method. Recent reports have criticized the deterministic approach, stating that it suffers from compounded conservatism by selecting upper percentiles or maximum values for multiple inputs and that it cannot directly determine what portion of the population a given criterion protects. As an alternative, probabilistic risk assessment (PRA) has been promoted as a more transparent and robust method for deriving AWQC. Probabilistic risk assessment offers several advantages over the deterministic approach. For example, PRA uses entire data distributions rather than upper-percentile point estimates to specify exposures, thereby reducing compounded conservatism. Additionally, because it links acceptable risk targets with specific segments of the exposed population, PRA-based AWQC demonstrably protects multiple subsets of the population. To date, no study has quantitatively compared deterministic and PRA approaches and resulting AWQC using national inputs consistent with USEPA guidance. This study introduces a PRA method for deriving AWQC and presents case studies to compare probabilistically derived AWQC with USEPA's 2015 recommendations. The methods and results of this work will help federal and state regulators, water quality managers, and stakeholders better understand available approaches to deriving AWQC and provide context to assumption- and method-specific differences between criteria. Integr Environ Assess Manag 2023;19:501-512. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Coliphages as viral indicators in municipal wastewater: A comparison between the ISO and the USEPA methods based on a systematic literature review

The use of traditional faecal indicator bacteria as surrogate organisms for pathogenic viruses in domestic wastewater has been noted as a problematic as concentrations and removal rates of bacteria and viruses do not seem to correlate. In this sense, bacteriophages (phages) emerge as potential viral indicators, as they are commonly found in wastewater in high levels, and can be quantified using simple, fast, low-cost methods. Somatic and F-specific coliphages comprise groups of phages commonly used as indicators of water quality. There are two internationally recognised methods to detect and enumerate coliphages in water samples, the International Standardization Organization (ISO) and the US Environmental Protection Agency (USEPA) methods. Both methods are based on the lysis of specific bacterial host strains infected by phages. Within this context, this systematic literature review aimed at gathering concentrations in raw and treated domestic wastewater (secondary, biological treatment systems and post-treatment systems), and removal efficiencies of somatic and F-specific coliphages obtained by ISO and USEPA methods, and then compare both methods. A total of 33 research papers were considered in this study. Results showed that the ISO method is more commonly applied than the USEPA method. Some discrepancies in terms of concentrations and removal efficiencies were observed between both methods. Higher removal rates were observed for both somatic and F-specific coliphages in activated sludge systems when using the USEPA method compared to the ISO method; in other secondary (biological) treatment systems, this was observed only for F-specific coliphages. The use of different standardised methods available might lead to difficulties in obtaining and comparing phage data in different conditions and locations. Future research comparing both ISO and USEPA methods as well as viral and bacterial pathogens and indicators in WWTP is recommended.

Dynamic prediction of effective runoff sediment particle size for improved assessment of erosion mitigation efficiency with vegetative filter strips

The most widely implemented mitigation measure to reduce transfer of surface runoff pesticides and other pollutants to surface water bodies are vegetative filter strips (VFS). The most commonly used dynamic model for quantifying the reduction by VFS of surface runoff, eroded sediment, pesticides and other pollutants is VFSMOD, which simulates reduction of total inflow (∆Q) and of incoming eroded sediment load (∆E) mechanistically during the rainfall-runoff event. These variables are subsequently used to calculate the reduction of pesticide load by the VFS (∆P). Since errors in ∆Q and ∆E propagate into ∆P, for strongly-sorbing compounds an accurate prediction of ∆E is crucial for a reliable prediction of ∆P. The most important incoming sediment characteristic for ∆E is the median particle diameter (d50). Current d50 estimation methods are simplistic, yielding fixed d50 based on soil properties and ignoring specific event characteristics and dynamics. We derive an improved dynamic d50 parameterization equation for use in regulatory VFS scenarios based on an extensive dataset of 93 d50 values and 17 candidate explanatory variables compiled from heterogeneous data sources and methods. The dataset was analysed first using machine learning techniques (Random Forest, Gradient Boosting) and Global Sensitivity Analysis (GSA) as a dimension reduction technique and to identify potential interactions between explanatory variables. Using the knowledge gained, a parsimonious multiple regression equation with 6 predictors was developed and thoroughly tested. Since three of the predictors are event-specific (eroded sediment yield, rainfall intensity and peak runoff rate), predicted d50 vary dynamically across event magnitudes and intensities. Incorporation of the improved d50 parameterization equation in higher-tier pesticide assessment tools with VFSMOD provides more realistic quantitative mitigation in regulatory US-EPA and EU FOCUS pesticide risk assessment frameworks. The equation is also readily applicable to other erosion management problems.

Assessment of factors affecting the diurnal variations of atmospheric PAHs based on a numerical simulation

Atmospheric polycyclic aromatic hydrocarbons (PAHs) are a type of organic pollutants that seriously endanger human health. Obtaining the diurnal variations of PAHs and clarifying their impact mechanisms are significant for the government to formulate targeted prevention and control measures. However, the influencing factors that dominate the diurnal variations of common PAHs are currently unclear. In order to solve this problem, 16 PAHs selected by the United States Environmental Protection Agency (EPA) as priority-controlled pollutants were simulated with high resolution. The simulation results were validated based on diurnal observations in the vertical direction. Although the model underestimated the particle-phase concentrations of most components, it captured their diurnal variations fairly well. In addition, we assessed the factors affecting the diurnal variations of PAHs with sensitivity tests, including chemical reactions and atmospheric diffusion. The results showed that the transforming ratios of PAHs by oxidants were higher during the day than that at night due to the dominant reactions with OH radical. Atmospheric dispersion affected the vertical distribution of PAHs, which resulted in higher day/night ratios at high altitudes than near the ground. We also compared the strength of atmospheric diffusion and chemical reaction on the diurnal trends of PAHs. Near the ground, atmospheric diffusion was the most dominant factor in determining their diurnal trends. At high altitudes, their diurnal trends were determined by a combination of atmospheric diffusion and chemical reactions. These findings can provide a comprehensive understanding of the diurnal variations of common PAHs, which are informative for the prevention and control of PAHs pollution.

Characterizing Asbestos Hazard Emergency Response Act (AHERA) Compliance in New Jersey: 2008-2017

CONTEXT

The Asbestos Hazard Emergency Response Act (AHERA) became a law in 1986, and the US Environmental Protection Agency (USEPA) was mandated to promulgate rules to regulate the inspection, management, and abatement of asbestos-containing building materials (ACBM) in schools. This study describes 10 years (2008-2017) of AHERA compliance site inspection data conducted by the New Jersey Department of Health (NJDOH).

OBJECTIVES

To establish the level to which inspected NJ schools comply with AHERA regulations, to characterize compliance deficiencies including those that may lead to increased asbestos exposure risk to students and school employees, and to determine whether age, type, and geographic location of school impacted the likelihood of noncompliance.

DESIGN

Information collected during 456 unique inspections between 2008 and 2017 was analyzed.

SETTING AND PARTICIPANTS

Inspections were conducted at public and private schools in New Jersey. These included elementary, middle, and high schools, as well as charter and vocational/technical schools.

MAIN OUTCOME MEASURES

Descriptive statistics and multiple logistic regression modeling of 3 factors, school type, geographical region, and school age.

RESULTS

NJDOH inspectors found damage to friable ACBM in 50% (n = 229) of the schools and fiber release episodes in 27% of inspections (n = 121). The case of schools failing to attach warning labels on or immediately adjacent to ACBM was the most frequently noted compliance deficiency over the 10-year period. The modeling output showed that compliance was associated with the type of school and geographical region.

CONCLUSIONS

Inspected schools during the 10-year period were in serious noncompliance with AHERA regulations. This included deficiencies that demonstrate a potential exposure to asbestos such as missing ACBM in management plans, damaged ACBM, lack of protection of short-term workers and custodial staff, and the identification of fiber release episodes. Modeling results of specific school characteristics can help direct limited resources to mitigate potential asbestos exposures.

National characterization of pesticide runoff and erosion potential to put USEPA standard ecological scenarios in context for pyrethroids

Decision-making for pesticide registration by the US Environmental Protection Agency (USEPA) relies upon crop-specific scenarios in a tiered framework. These standard modeling scenarios are stated to represent "…sites expected to produce runoff greater than would be expected at 90% of the sites for a given crop/use." This study developed a novel approach to compare the pesticide runoff + erosion (Sum_RE ) mass flux potential of a hydrophobic chemical using 36 of these ecological regulatory scenarios with national-scale distributions of modeled Sum_RE from over 750 000 USA-wide agricultural catchments to provide real-world context for the simulated transport predictions used for regulatory decision-making. For the standard scenarios and national scale modeling, "edge of field" Sum_RE mass flux was estimated using regulatory guidance for a hypothetical pyrethroid. The national-scale simulations were developed using publicly available soil, hydrography, and crop occurrence /regional timings databases. Relevant soil and crop combinations identified by spatial overlay along with weather data were used in a regulatory model to generate daily Sum_RE estimates, which were assigned to the catchments. The resulting average annual total Sum_RE mass fluxes were ranked to produce distributions to compare with the standard regulatory scenario outputs. These comparisons showed that Sum_RE flux from 25 of the 36 USEPA ecological regulatory crop-specific scenarios modeled ranked above the 99^th percentile of pyrethroid runoff + erosion vulnerability from any catchment growing that crop; Sum_RE flux from six scenarios was more severe than any catchment. For 12 USEPA regulatory scenarios, the resulting eroded sediment corresponds to highly erodible land (HEL), which the US Department of Agriculture mandates should not be cropped without substantial additional erosion prevention controls for sustainability. Since the pesticide regulatory framework already incorporates many acknowledged assumptions to ensure it conservatively meets protection goals, these HEL observations suggest that the standard scenarios overestimate potential aquatic exposure and that the regulatory process is more protective than intended. Integr Environ Assess Manag 2023;19:175-190. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

A wide range of toxic VOCs measured by dual-sorbent passive sampling with validation by field online measurements

This study modified a passive sampling technique similar to the US EPA Method 325 A/B method but extended to include more toxic volatile organic compounds (VOCs) under varied climate conditions to enhance field applicability. A mixing chamber was built to determine uptake rates (Us) for the target compounds. It was found that the Us of 27 air toxics previously reported in the literature agreed reasonably well with our findings within 18%, thus proving the chamber's integrity. To broaden the compound coverage, both Carbopack X and Carboxen 569 were studied for a suite of toxic VOCs to meet stringent quality control (QC) criteria of correlation coefficients (R-square), method detection limits (MDL), back diffusion (BD), storage stability, as well as a wide range of climate conditions in temperature and humidity. After excluding the species that failed to pass any of the QC criteria, Carbopack X was found to fit 50 air toxics, whereas Carboxen 569 held 37. After excluding the overlapped species, 61 toxic VOCs can be determined with robust Us for a broad range of climate conditions when the two sorbents are used in pairs. A one-week field measurement was conducted to compare with the online thermal desorption gas chromatography-mass spectrometry (TD-GC-MS) with hourly data resolution. The field passive sampling showed comparable results to the means of the online hourly measurements, despite the high variability of selected target compounds, such as toluene from 0.3 ppbv as the 5th percentile to the maximum of about 80 ppbv. Passive sampling clearly demonstrated the ability to smooth out concentration variability and thus the time-averaging strength of toxic VOCs, revealing its ideal role as an exposure monitor over time. The passive sampling method can be more desired than active sampling or online methods when the aim is simply the knowledge of prolonged time-averaged concentrations.

The association between tree planting and mortality: A natural experiment and cost-benefit analysis

Several recent longitudinal studies have found that exposure to the natural environment is associated with lower non-accidental mortality. However, most of these studies used the normalized difference vegetation index (NDVI) as an exposure metric; and because NDVI might not be sensitive enough to adequately capture changes in urban vegetation, these studies might lack true longitudinal variation in exposure. Therefore, we used a natural experiment to assess the impact of 30 years of tree planting by the nonprofit Friends of Trees on non-accidental, cardiovascular, lower-respiratory, and accidental mortality in Portland, Oregon (mortality data were provided by the Oregon Health Authority). We estimated autoregressive mixed models of Census-tract level mortality rate (deaths per 100,000 population) associated with trees planted, including a tract-level random effect. All models used data from the American Community Survey to control for year, race, education, income, and age. Each tree planted in the preceding 15 years was associated with significant reductions in non-accidental (-0.21, 95 % CI: -0.30, -0.12) and cardiovascular mortality (-0.066, 95 % CI: -0.11, -0.027). Furthermore, the dose-response association between tree planting and non-accidental mortality increased in magnitude as trees aged and grew. Each tree planted in the preceding 1-5 years was associated with a reduction in mortality rate of -0.154 (95 % CI: -0.323, 0.0146), whereas each tree planted in the last 6-10 and 11-15 years was associated with a reduction in mortality rate of -0.262 (95 % CI: -0.413, -0.110) and -0.306 (95 % CI: -0.527, -0.0841) respectively. Using US EPA estimates of a value of a statistical life, we estimated that planting a tree in each of Portland's 140 Census tracts would generate $14.2 million in annual benefits (95 % CI: $8.0 million to $20.4 million). In contrast, the annual cost of maintaining 140 trees would be $2,716-$13,720.

Inferring global surface HCHO concentrations from multisource hyperspectral satellites and their application to HCHO-related global cancer burden estimation

Formaldehyde (HCHO) is a toxic and hazardous air pollutant that widely exists in atmosphere. Insufficient spatial and temporal coverage of surface HCHO measurements is limiting studies on surface HCHO-related air quality management and health risk assessment. This study develops a method to derive global ground-level HCHO concentrations from satellite-based tropospheric HCHO columns using TM5-simulated surface-to-column conversion factor with coarse spatial resolution. The method improves the factor more representative in finer grids by constraining TM5-simulated vertical profile shapes with satellite HCHO columns. The surface HCHO concentrations derived by the Ozone Mapping and Profiler Suite (OMPS) show good correlation with in situ HCHO measurements (R = 0.59) from the U.S. Environmental Protection Agency surface network. We investigated how surface HCHO relates to urbanization and population aggregation over seven regions with high HCHO pollution. The results show urban HCHO increases as a power function with population size in China, India, and West Asia. HCHO concentrations in rural aeras also present strong log-log relationship with population aggregation in China, India, the United States, and Europe. Moreover, OMPS-derived ground-level HCHO concentrations were used to estimate global cancer burden caused by long-term outdoor HCHO exposure. The results show that up to 418188 more people worldwide will develop this cancer during the human life cycle. The global cancer burden is mainly from the South-East Asia region (33.11 %) and the Western Pacific region (22.95 %). This cancer occurrence in India and China is ranked 1st and 2nd in the world due to the large population size and serious HCHO pollution. Besides, global surface HCHO concentrations and cancer burden derived from the Environmental Trace Gases Monitoring Instrument which is China's first hyperspectral space-based spectrometer are found similar patterns with that from OMPS. Our results provide new insight into the impact of population urbanization on HCHO pollution and global outdoor HCHO-caused health risks.

Treatment of the red tide dinoflagellate Karenia brevis and brevetoxins using USEPA-registered algaecides

The effectiveness of USEPA-registered algaecides for managing algae in lakes and reservoirs has been extensively evaluated in laboratory studies, mesocosm studies and in situ treatment. However, the use of these algaecides in marine environments for the management of dinoflagellates and associated toxins remains largely unknown. Karenia brevis is a toxic dinoflagellate that causes red tides in the Gulf of Mexico. In this study, we investigated the efficacy of six USEPA-registered algaecides, three copper-based and three peroxide-based, on treating toxic K. brevis with a natural bloom density (1.79 × 10⁷ cells/L). Our results indicate that the application of as low as 0.31-0.34 mg Cu/L led to a significant decrease of K. brevis cells within 24 h after treatment, while peroxide-based algaecides required a relatively higher concentration for the effective removal of K. brevis cells (4.89-7.08 mg H₂O₂/L), but still lower than maximum label rate. Total brevetoxin levels 72 h after treatment revealed that 1.00 mg Cu/L for Algimycin® PWF, 6.48 mg H₂O₂/L for PAK® 27 and 7.08 mg H₂O₂/L for Oximycin® P5 had the greatest impact on decreasing toxin levels. The correlation analysis showed that brevetoxin reduction rate was significantly positively related with the peroxide-based algaecide exposure concentration, which is caused by the oxidation of hydroxyl radicals produced by hydrogen peroxide. The degradation dynamics of the three peroxide-based algaecides revealed that salinity, microorganisms and organic matter (≥ 0.2 μm) impact the stability of hydrogen peroxide, and Oximycin® P5 showed the highest stability among tested peroxide-based algaecides with a degradation rate of 0.467 mg/d in natural seawater. Hence, our laboratory work provided new insights into potential emergency treatment methods for immediate mitigation of K. brevis and brevetoxins. More work on the fate and persistence of algaecide active ingredients and phycotoxins, effects of site characteristics, and pilot studies on marine non-targets are still needed before safe application of this method for HABs in marine systems.

Systematic evidence map (SEM) template: Report format and methods used for the US EPA Integrated Risk Information System (IRIS) program, Provisional Peer Reviewed Toxicity Value (PPRTV) program, and other "fit for purpose" literature-based human health analyses

BACKGROUND

Systematic evidence maps (SEMs) are gaining visibility in environmental health for their utility to serve as problem formulation tools and assist in decision-making, especially for priority setting. SEMs are now routinely prepared as part of the assessment development process for the US Environmental Protection Agency (EPA) Integrated Risk Information System (IRIS) and Provisional Peer Reviewed Toxicity Value (PPRTV) assessments. SEMs can also be prepared to explore the available literature for an individual chemical or groups of chemicals of emerging interest.

OBJECTIVES

This document describes the typical methods used to produce SEMs for the IRIS and PPRTV Programs, as well as "fit for purpose" applications using a variety of examples drawn from existing analyses. It is intended to serve as an example base template that can be adapted as needed for the specific SEM. The presented methods include workflows intended to facilitate rapid production. The Populations, Exposures, Comparators and Outcomes (PECO) criteria are typically kept broad to identify mammalian animal bioassay and epidemiological studies that could be informative for human hazard identification. In addition, a variety of supplemental content is tracked, e.g., studies presenting information on in vitro model systems, non-mammalian model systems, exposure-level-only studies in humans, pharmacokinetic models, and absorption, distribution, metabolism, and excretion (ADME). The availability of New Approach Methods (NAMs) evidence is also tracked (e.g., high throughput, transcriptomic, in silico, etc.). Genotoxicity studies may be considered as PECO relevant or supplemental material, depending on the topic and context of the review. Standard systematic review practices (e.g., two independent reviewers per record) and specialized software applications are used to search and screen the literature and may include the use of machine learning software. Mammalian bioassay and epidemiological studies that meet the PECO criteria after full-text review are briefly summarized using structured web-based extraction forms with respect to study design and health system(s) assessed. Extracted data is available in interactive visual formats and can be downloaded in open access formats. Methods for conducting study evaluation are also presented which is conducted on a case-by-case basis, depending on the usage of the SEM.

Simulating toxicokinetic variability to identify susceptible and highly exposed populations

BACKGROUND

Toxicokinetic (TK) data needed for chemical risk assessment are not available for most chemicals. To support a greater number of chemicals, the U.S. Environmental Protection Agency (EPA) created the open-source R package "httk" (High Throughput ToxicoKinetics). The "httk" package provides functions and data tables for simulation and statistical analysis of chemical TK, including a population variability simulator that uses biometrics data from the National Health and Nutrition Examination Survey (NHANES).

OBJECTIVE

Here we modernize the "HTTK-Pop" population variability simulator based on the currently available data and literature. We provide explanations of the algorithms used by "httk" for variability simulation and uncertainty propagation.

METHODS

We updated and revised the population variability simulator in the "httk" package with the most recent NHANES biometrics (up to the 2017-18 NHANES cohort). Model equations describing glomerular filtration rate (GFR) were revised to more accurately represent physiology and population variability. The model output from the updated "httk" package was compared with the current version.

RESULTS

The revised population variability simulator in the "httk" package now provides refined, more relevant, and better justified estimations.

SIGNIFICANCE

Fulfilling the U.S. EPA's mission to provide open-source data and models for evaluations and applications by the broader scientific community, and continuously improving the accuracy of the "httk" package based on the currently available data and literature.

Exposure forecasting - ExpoCast - for data-poor chemicals in commerce and the environment

Estimates of exposure are critical to prioritize and assess chemicals based on risk posed to public health and the environment. The U.S. Environmental Protection Agency (EPA) is responsible for regulating thousands of chemicals in commerce and the environment for which exposure data are limited. Since 2009 the EPA's ExpoCast ("Exposure Forecasting") project has sought to develop the data, tools, and evaluation approaches required to generate rapid and scientifically defensible exposure predictions for the full universe of existing and proposed commercial chemicals. This review article aims to summarize issues in exposure science that have been addressed through initiatives affiliated with ExpoCast. ExpoCast research has generally focused on chemical exposure as a statistical systems problem intended to inform thousands of chemicals. The project exists as a companion to EPA's ToxCast ("Toxicity Forecasting") project which has used in vitro high-throughput screening technologies to characterize potential hazard posed by thousands of chemicals for which there are limited toxicity data. Rapid prediction of chemical exposures and in vitro-in vivo extrapolation (IVIVE) of ToxCast data allow for prioritization based upon risk of adverse outcomes due to environmental chemical exposure. ExpoCast has developed (1) integrated modeling approaches to reliably predict exposure and IVIVE dose, (2) highly efficient screening tools for chemical prioritization, (3) efficient and affordable tools for generating new exposure and dose data, and (4) easily accessible exposure databases. The development of new exposure models and databases along with the application of technologies like non-targeted analysis and machine learning have transformed exposure science for data-poor chemicals. By developing high-throughput tools for chemical exposure analytics and translating those tools into public health decisions ExpoCast research has served as a crucible for identifying and addressing exposure science knowledge gaps.

Use of systematic evidence maps within the US environmental protection agency (EPA) integrated risk information system (IRIS) program: Advancements to date and looking ahead

Systematic evidence maps (SEMs) are increasingly used to inform decision-making and risk management priority-setting and to serve as problem formulation tools to refine the focus of questions that get addressed in full systematic reviews. Within the U.S. Environmental Protection Agency (EPA) Office of Research and Development (ORD) Integrated Risk Information System (IRIS), SEMs have been used to inform data gaps, determine the need for updated assessments, inform assessment priorities, and inform development of study evaluation considerations, among other uses. Increased utilization of SEMs across the environmental health field has the potential to increase transparency and efficiency for data gathering, problem formulation, read-across, and evidence surveillance. Use of the SEM templates published in the companion text (Thayer et al.) can promote harmonization in the environmental health community and create more opportunities for sharing extracted content.

Multiscale Methane Measurements at Oil and Gas Facilities Reveal Necessary Frameworks for Improved Emissions Accounting

Methane mitigation from the oil and gas (O&G) sector represents a key near-term global climate action opportunity. Recent legislation in the United States requires updating current methane reporting programs for oil and gas facilities with empirical data. While technological advances have led to improvements in methane emissions measurements and monitoring, the overall effectiveness of mitigation strategies rests on quantifying spatially and temporally varying methane emissions more accurately than the current approaches. In this work, we demonstrate a quantification, monitoring, reporting, and verification framework that pairs snapshot measurements with continuous emissions monitoring systems (CEMS) to reconcile measurements with inventory estimates and account for intermittent emission events. We find that site-level emissions exhibit significant intraday and daily emission variations. Snapshot measurements of methane can span over 3 orders of magnitude and may have limited application in developing annualized inventory estimates at the site level. Consequently, while official inventories underestimate methane emissions on average, emissions at individual facilities can be higher or lower than inventory estimates. Using CEMS, we characterize distributions of frequency and duration of intermittent emission events. Technologies that allow high sampling frequency such as CEMS, paired with a mechanistic understanding of facility-level events, are key to an accurate accounting of short-duration, episodic, and high-volume events that are often missed in snapshot surveys and to scale snapshot measurements to annualized emissions estimates.

Reference dose prediction by using CDK molecular descriptors: A non-experimental method

Reference dose (RfD) is an estimate of a daily dose that individual can be exposed chronically without obvious deleterious effects during a lifetime. In the area of toxicology, researchers always use the traditional approach by employing NOAEL/LOAEL or the benchmark dose (BMD) and other dose-response approaches to estimate RfD. These methods have, despite their typicalness, certain limitations. In this study, we present a novel method of the estimation of reference dose without experiments. The information of the organic chemicals is available from the Integrated Risk Information System (IRIS) of USEPA. Molecular descriptors for each molecular structure were calculated by an integrated platform, and the chemicals were classified into four categories based on molecular similarity: 128 contained benzene rings, 47 were heteroaromatics, 104 contained halogen substituents and 44 were halogenated aliphatic hydrocarbons. The predictive model of RfD was constructed by the multiple linear stepwise regression (MLR) method. Approximately 95% and 82% of the data points differ by less than 10-fold and 5-fold between the predicted values and the true values respectively. The non-experimental method improves the estimation efficiency and has a certain reference value to predict.

Toxic Substances Control Act (TSCA) Implementation: How the Amended Law Has Failed to Protect Vulnerable Populations from Toxic Chemicals in the United States

Exposures to industrial chemicals are widespread and can increase the risk of adverse health effects such as cancer, developmental disorders, respiratory effects, diabetes, and reproductive problems. The amended Toxic Substances Control Act (amended TSCA) requires the U.S. Environmental Protection Agency (EPA) to evaluate risks of chemicals in commerce, account for risk to potentially exposed and susceptible populations, and mitigate risks for chemicals determined to pose an unreasonable risk to human health and the environment. This analysis compares EPA's first 10 chemical risk evaluations under amended TSCA to best scientific practices for conducting risk assessments. We find EPA's risk evaluations underestimated human health risks of chemical exposures by excluding conditions of use and exposure pathways; not considering aggregate exposure and cumulative risk; not identifying all potentially exposed or susceptible subpopulations, and not quantifying differences in risk for susceptible groups; not addressing data gaps; and using flawed systematic review approaches to identify and evaluate the relevant evidence. We present specific recommendations for improving the implementation of amended TSCA using the best available science to ensure equitable, socially just safeguards to public health. Failing to remedy these shortcomings will result in continued systematic underestimation of risk for all chemicals evaluated under amended TSCA.

Systematic review of the scientific evidence on ethylene oxide as a human carcinogen

Ethylene oxide is a highly reactive chemical primarily used as an intermediate in chemical production and as a sterilant of medical equipment and food products; it also is produced endogenously as a result of physiological processes. We conducted a systematic review of the potential carcinogenicity of inhaled ethylene oxide in humans using methods that adhere to PRIMSA guidelines and that incorporate aspects from the Institute of Medicine (IOM) (now the National Academy of Medicine) as well as several US Environmental Protection Agency (EPA) frameworks for systematic reviews. After a comprehensive literature search and selection process, study quality was evaluated following a method adapted from the EPA Toxic Substances Control Act (TSCA) framework. The literature screening and selection process identified 24 primary studies in animals or humans and more than 50 mechanistic studies. Integrating epidemiological, animal, and mechanistic literature on ethylene oxide and cancer according to the IOM framework yielded classifications of suggestive evidence of no association between ethylene oxide and stomach cancer, breast cancer and lymphohematopoietic malignancies at human relevant exposures. However, we acknowledge that there is additional uncertainty in the classification for lymphohematopoietic malignancies owing to a paucity of evidence for specific types of these tumors, each of which is a distinct disease entity of possibly unique etiology.

Parameterization of a Brazilian scenario in the USEPA Pesticide in Water Calculator tool to estimate the environmental exposure of pesticide in surface waters

The current pesticide registration process in Brazil is mainly hazard-based and does not consider exposure and therefore risk. However, the scenario prompted changes and discussions about risk assessments by Brazilian environmental regulatory agencies. The US Environmental Protection Agency's (EPA) Pesticide in Water Calculator (PWC) model is used as a regulatory tool for aquatic exposure assessment in Canada and the USA for exposure evaluation of agrochemical products; nevertheless, the available scenarios only consider North American local conditions. This work aims to demonstrate a parametrization of the PWC model for a Brazilian scenario, considering the active ingredient glyphosate and sugarcane agronomic practices. The estimated environmental concentrations (EECs) obtained were compared with two standard EPA scenarios. Essential parameter data to build a specific local scenario were collected from the literature and official Brazilian databases. The EECs (1-in-10 years) of glyphosate according to the conditions established were 1.427 μg L^-1 (1st day), 0.382 µg L^-1 (21st day), and 0.2027 µg L^-1 (60th day). These values can be used as exposure elements in acute and chronic risk assessments considering the agricultural practices used in the developed scenario. A 4.45-fold and 1.28-fold difference was found comparing the 1-day (1-in-10 years) average concentration of the Brazilian scenario with two EPA standard scenarios. Such a difference may affect the outcome of risk assessments, affecting regulatory decisions. This demonstrates the importance of generating more realistic scenarios for Brazil, yielding surface water EECs that consider local conditions. Integr Environ Assess Manag 2022;18:1387-1398. © 2021 SETAC.

Advances in computational methods along the exposure to toxicological response paradigm

Human health risk assessment is a function of chemical toxicity, bioavailability to reach target biological tissues, and potential environmental exposure. These factors are complicated by many physiological, biochemical, physical and lifestyle factors. Furthermore, chemical health risk assessment is challenging in view of the large, and continually increasing, number of chemicals found in the environment. These challenges highlight the need to prioritize resources for the efficient and timely assessment of those environmental chemicals that pose greatest health risks. Computational methods, either predictive or investigative, are designed to assist in this prioritization in view of the lack of cost prohibitive in vivo experimental data. Computational methods provide specific and focused toxicity information using in vitro high throughput screening (HTS) assays. Information from the HTS assays can be converted to in vivo estimates of chemical levels in blood or target tissue, which in turn are converted to in vivo dose estimates that can be compared to exposure levels of the screened chemicals. This manuscript provides a review for the landscape of computational methods developed and used at the U.S. Environmental Protection Agency (EPA) highlighting their potentials and challenges.