BACKGROUND:Soil screening levels (SSLs) are an important guidance tool for identifying sites where exposure to soil contaminants may pose health risks to people residing or working nearby; however, to date, no soil screening levels or default exposure scenario have been established specifically for farmworkers who have frequent, direct soil contact through their typical occupational tasks and behaviors. OBJECTIVE:We developed an exposure scenario for a vegetable farmworker's soil exposure. We apply this exposure scenario to derive and compare noncarcinogenic-based soil screening levels for four PFAS commonly detected in soil from farm fields with a history of land application of biosolids in Maine. METHODS:We used existing EPA models for incidental soil ingestion and dermal contact, parameterizing model inputs with distributions drawn from the literature to be more representative for farmworkers. We developed an empirical model of the inhalation pathway using literature-reported exposure and time-activity data. We used Monte Carlo simulation to evaluate these models with toxicity values in the EPA Regional Screening Levels database to derive SSLs for the individual and combined pathways and compared these results to soil PFAS levels from a statewide testing program of biosolids-amended farmland. RESULTS:The 5th percentile values from the distribution of combined pathway SSLs were 26, 7.9, 790, and 0.5 ng/g for PFOS, PFOA, PFNA, and PFDA, respectively. Sensitivity analyses identified the incidental soil ingestion rate as the most influential parameter in deriving a SSL for our farmworker scenario. We found overlap for PFOS, PFOA, and PFDA in the distributions of plausible SSLs for a vegetable farmworker scenario and measured soil levels from a statewide testing program. SIGNIFICANCE:Our comparison of these farmworker SSLs to more routinely evaluated adult exposure scenarios (residential, outdoor worker, construction worker) indicated that these other scenarios may not be protective of farmworkers. IMPACT STATEMENT:The farmworker exposure scenario and PFAS soil screening levels we developed are a novel and necessary public health tool for protecting farmworkers from exposure to contaminants in soils and informing risk management decisions for farms and fields amended with biosolids.

BackgroundPathogenic and chemical contaminants in biosolids may pose risks to workers during land application. Characterizing biosolids applicators' exposures and risks requires information about the tasks and processes involved in the transportation, application, and use of biosolids, which is critically lacking.ObjectiveThis mixed-methods study aims to characterize the tasks and processes that influence occupational exposure to biosolids during land application and generate preliminary task-specific exposure factors to refine exposure assessments for contaminants in biosolids.MethodsWe conducted semi-structured, in-depth interviews with biosolids workers who apply, transport, and/or use biosolids in the United States and Canada. Following a framework approach to analysis, we identified the six tasks that constitute biosolids application and developed and administered a biosolids exposure questionnaire to collect preliminary data to derive exposure factors for use in occupational risk assessments.ResultsWorkers described frequent and direct contact with biosolids across six land application tasks: hauling, loading, spreading, post-application field work, cleaning, and maintenance. They mentioned instances of ingestion of biosolids, soil, dust, and aerosolized biosolids (spray), inhalation of dust, gases, odors, and aerosolized biosolids (spray), and dermal exposure to biosolids, soil, and dust. Cleaning and maintaining equipment and spreading biosolids were the most commonly reported tasks. Though workers reported spending the least amount of time cleaning and maintaining equipment, these tasks generally resulted in the greatest direct contact with biosolids.SIGNIFICANCEWorkers' descriptions of direct contact with biosolids across all exposure routes indicate that land application represents a high-end exposure scenario that warrants further analysis. Our work fills a gap in understanding the behavior and exposure patterns of professional biosolids land applicators and presents preliminary data that can be used for deriving exposure factors for occupational receptors in biosolids risk assessments.Impact StatementExposure to contaminants in biosolids may result in undue health risks, particularly for workers who interact directly with biosolids when applying them to land as a soil amendment. Our mixed-methods exploration of land applicators' tasks, behaviors, and exposure patterns offers critical information for accurately assessing occupational exposure and identifying potential points of intervention.

Background Environmental exposure to heavy metals such as lead (Pb), arsenic (As), hexavalent chromium [Cr(VI)], and cadmium (Cd), (PACC), is linked to neurodevelopmental disorders. These metals often co-occur in contaminated environments, but their combined effects on brain development remain poorly understood. Objective To test the hypothesis that perinatal exposure to a mixture of environmentally relevant levels of Pb, As, Cd, and Cr(VI), causes developmental defects in cognition, behavior, and neuronal function. Methods Female C57BL/6J mice were exposed to either a single metal or the PACC mixture in drinking water. Exposure began two weeks preconception and continued until weaning at postnatal day 21. Juvenile mice were tested at 4-5 weeks of age in open field (locomotion), novel object recognition (short-term memory), Y-maze (working memory), and elevated plus maze (anxiety-like behavior). A subset of animals underwent Whole-cell patch-clamp recordings in the medial prefrontal cortex (mPFC) and hippocampal CA1 neurons. Results Perinatal exposure to PACC metal mixture increased anxiety-like behavior and impaired short-term memory but not locomotion or working memory. Pyramidal neurons in mPFC and hippocampal CA1 displayed increased intrinsic excitability, mPFC neurons also showed elevated amplitude in spontaneous excitatory postsynaptic currents. Discussion Our findings suggest that perinatal exposure to the PACC metal mixture impairs cognition, increases anxiety-like behavior, and alters neuronal function in specific brain regions of juvenile mice, leading to disruption in neuronal function and behavior. Further studies are needed to provide mechanistic insight into how perinatal heavy metal exposure affects neuronal development.

Extraintestinal pathogenic Escherichia coli (ExPEC) is the leading cause of urinary tract infections (UTIs) worldwide and may be transmitted from food animals to humans via contaminated meat. However, the contribution of zoonotic ExPEC strains to UTIs in metropolitan areas remains unclear. We estimated the proportion of UTIs attributable to zoonotic ExPEC across eight Southern California counties. Between 2017 and 2021, we collected 12,616 E. coli isolates from retail meat and 23,483 from UTI patients, sequencing a representative subset of 5,728 isolates. Using a Bayesian latent class model trained with 17 host-associated genetic markers, we inferred the host origin of each isolate. Demographic, clinical, and antimicrobial resistance profiles were compared between meat isolates and clinical isolates inferred to be of human or food-animal origin. Most UTI patients were female (88%), with a median age of 50 years; 37% were Hispanic and 31% non-Hispanic white. Zoonotic ExPEC strains accounted for 18% of UTIs overall, rising to 21.5% in high-poverty neighborhoods. Women had a higher zoonotic proportion than men (19.7% vs 8.5%, P < 0.001). Among men, those with zoonotic infections were older than those with non-zoonotic infections (median 73.0 vs 65.0 years, P = 0.028). These findings underscore the contribution of zoonotic ExPEC to the UTI burden in Southern California and the need for targeted interventions to reduce risk in vulnerable communities.IMPORTANCEUrinary tract infections (UTIs) are among the most common bacterial infections worldwide and are primarily caused by Escherichia coli. While E. coli is known to colonize both humans and food-producing animals, the extent to which zoonotic strains impact human disease remains poorly understood. Emerging evidence suggests that food animals may serve as an underrecognized reservoir for extraintestinal pathogenic E. coli (ExPEC). In this study, we used a genomic attribution model to quantify the contribution of zoonotic strains to UTIs in Southern California. We found that approximately 18% of E. coli UTIs were likely attributable to food animals. Individuals living in high-poverty neighborhoods had a 1.6-fold increased risk of zoonotic UTIs compared to those in low-poverty areas. These findings highlight zoonotic transmission as an important driver of UTIs and suggest that reducing ExPEC in food-animal reservoirs could help lower disease burden and address health disparities.

Background Meat, milk, and egg production is increasingly taking place in intensive animal feeding operations. Although these operations generate chemical, biological, and other hazardous agents in the surrounding environment, the health risks to people living in adjacent communities are unclear.Objective To conduct a systematic review to determine whether a relationship exists between human health and community exposure to operations where animals are produced for food.Methods A comprehensive search strategy was developed to retrieve relevant studies from Medline (Ovid), Global Health (Ovid), Embase.com, Scopus, and Web of Science databases. Title/abstract and full-text screening by two independent reviewers will be conducted to identify relevant studies. We will include primary research studies focused on humans who live near animal feeding operations. Details regarding study design, study population, and health outcomes will be extracted. The Navigation Guide methodology will be used to conduct a risk of bias assessment. Meta-analysis for selected outcomes will be conducted if possible; other quantitative or qualitative approaches will also be utilized to summarize the outcome data.Discussion This systematic review will provide an updated assessment of the association between community exposure to animal feeding operations and the health of people living in adjacent communities.

Communities in southeastern Louisiana are subject to disproportionate environmental health burdens, including elevated risk for cancer, from emissions of industrial hazardous air pollutants (HAPs). However, there are few ambient measurements (or none) of various HAPs in the heavily industrialized corridor between Baton Rouge and New Orleans (BR-NO). We measured 17 carcinogenic volatile organic compounds using fast-response in situ instrumentation aboard a mobile laboratory. Using spatially resolved concentrations, we estimate cancer risk in 15 census tracts along an 81 km-long stretch of the BR-NO corridor. In 14 of 15 tracts, our estimates of total cancer risk were higher (range: 0.9 to 11.6[Formula: see text]; median: 5[Formula: see text]) than those from the U.S. Environmental Protection Agency's (USEPA) 2020 Air Toxics Screening Assessment (AirToxScreen). Our maximum estimate for total tract-level cancer risk was 560-in-one million excess cancer cases, far exceeding the upper limit of USEPA's acceptable risk range (100-in-one million). This discrepancy is largely explained by differences between measured vs. modeled ethylene oxide concentrations, though there are important contributions from a number of additional HAPs. Our risk estimates are dominated by ethylene oxide, which contributes between 39.5 and 92.2% of total cancer risk across all tracts; chloroprene (0.2 to 36.8%); and formaldehyde (4.1 to 14.6%). AirToxScreen also identifies these three compounds as primary drivers of risk in this location. Together, these three compounds account for between 63 and 96.9% of total cancer risk. There is substantial spatial variability in total cancer risk and the relative contribution of each HAP, both between and within tracts. These data substantiate claims that the region has high HAPs-related cancer risk and quantify which individual HAPs are of highest concern.

Time-activity pattern data are components of EPA’s efforts to develop soil and dust ingestion rate recommendations for use in risk assessment. The existing database of activity pattern data used for this purpose is comprised mostly of studies designed to estimate exposure to air pollution that are decades old, limiting their applicability to estimating soil and dust ingestion. We aimed to generate novel time-activity pattern data germane to soil and dust ingestion for children aged 6 months to 6 years. We explore potential differences in key exposure factors by child age, sex, motor development, season, and day of the week, and we compare our estimates to the USEPA’s Exposure Factors Handbook (EFH) recommendations. Caregivers completed hourly time-activity surveys on one weekday and one weekend day in each season across one calendar year. We collected data on four microenvironments, seven activities, and several play-related parameters specific to soil and dust exposure. We assessed differences in time spent and engaged in these microenvironments and activities across day of the week, season, and calendar and developmental lifestage using clustered bootstrapping. We collected 1010 participant-days of time-activity pattern data representing 242 children <6 years. Children spent most of their day indoors either sleeping (51

Anaerobic manure digesters are a hotly debated and rapidly expanding technology that extracts biogas from animal manure. We assessed claims by proponents and opponents of the technology by reviewing evidence regarding digesters and pollutant emissions, occupational health, environmental injustice, economics, and climate. Manure digesters can mitigate some impacts from industrial animal agriculture, such as odors and methane emissions, while potentially increasing or perpetuating others, such as ammonia emissions and nutrient pollution. While promoted as a climate solution, manure digesters only address a fraction of livestock-related greenhouse gas emissions and may exacerbate or introduce new occupational and community hazards, such as from flared biogas. Policies play a large role in subsidizing manure digesters, incentivizing further expansion of industrial animal agriculture—an industry with documented harms to rural populations. In summary, proponent claims in many cases overstated the evidence of actual benefits, while opponent concerns were either validated by the evidence or merit further investigation. Based on the current state of available evidence, manure digesters should not be promoted as a solution for manure management and energy production.

BACKGROUND:Cumulative risk assessment (CRA) is key to characterizing health risks in fenceline and disadvantaged communities, which face environmental pollution and challenging socioeconomic conditions. Traditional approaches for inclusion of mixtures in CRA are limited and only assess the most sensitive target organ system for each chemical. METHODS:We developed an expanded approach to cumulative risk assessment that considers all known target organ systems associated with a chemical. Specifically, we created a multi-effects toxicity database by a) compiling toxicological and epidemiological data from the Agency for Toxic Substances and Disease Registry's (ATSDR) Toxicological Profiles and the Environmental Protection Agency (US EPA) CompTox Chemicals Dashboard; b) developing a tiering system to prioritize identified data for use in developing toxicity values; and c) accounting for uncertainty to create toxicity values for additional target organ systems. We demonstrated differences between the traditional approach and our expanded approach by using state-of-the-art mobile monitoring data from our Southeastern Pennsylvania Hazardous Air Pollutant Monitoring and Assessment Project (SEPA HAP-MAP) to conduct a cumulative risk assessment. RESULTS:Of the 32 chemicals quantified in SEPA HAP-MAP, 28 were represented in our multi-effects toxicity database, whereas only 16 were included using a traditional approach. In total, we derived toxicity values for 172 chemical-target organ system combinations. Our expanded approach found neurological, renal, respiratory, endocrine, and systemic risks (hazard index >1) in SEPA HAP-MAP fenceline communities, whereas no risks were identified using a traditional approach limited to the most sensitive target organ systems only. CONCLUSION:Our results suggest that traditional approaches to CRA underestimate health risks in fenceline and other highly exposed communities and highlight the need for improved methods to inform health-protective and just risk management decisions. https://doi.org/10.1289/EHP14696.

Environmental exposures, including widespread industrial pollution, impact human health and are amplified in more highly exposed communities. Policy and regulatory frameworks for making decisions and recommendations on interventions to mitigate or prevent exposures tend to narrowly focus on exposure and some health-related data related to risks. Typically, such frameworks do not consider other factors, including essentiality, health equity, and distribution of benefits and costs. Further, decisions and recommendations lack transparency regarding how they were developed. We developed the Navigation Guide Evidence-to-Decision Framework for Environmental Health (E2DFEH) to provide a structured and transparent framework incorporating a range of scientific information and factors for decision-making. We reviewed current evidence-to-decision frameworks and engaged in an iterative consensus-based process involving 30 experts from 25 organizations in the academic, government, and nonprofit sectors. The E2DFEH framework includes three Foundations that are structural factors considered as part of recommendation development: 1) Essentiality, 2) Human Rights, and 3) Quality of the Evidence. It also includes three core Criteria that guide the development of a specific recommendation, informed by an evaluation of relevant evidence: 1) Environmental Justice, 2) Maximizing Benefits and Reducing Harm, and 3) Sociocultural Acceptability and Feasibility. The framework's goal is to make the decision process transparent and comprehensive through explicit consideration of core factors important for decisions, leading to more equitable and health-protective interventions.

Estimates of microactivity (e.g., hand- and object-to-mouth contact) frequencies are essential for modeling children’s environmental exposures but are challenging to obtain due to the time and human costs of manually labeling behaviors from pre-recorded videos. We aim to develop and evaluate a computer vision model to quantify microactivities for young children. The vision model was trained and validated using video footage (collected via four concurrent Go-Pro cameras) of 25 children 6–18 months playing in their homes in Baltimore, MD. We leveraged computer vision techniques to develop an algorithm to assess children’s pose by identifying and tracking 3D key points (e.g., locations of children’s eyes, hands, wrists, elbows, etc.). We enabled automatic measurement to track the distance between the child’s hands and mouth in every video frame. When the distance reached a minimum threshold, the model logged a “contact event.” We compared the timing and number of events for three microactivities (left- and right-hand-to-mouth, and object-to-mouth) yielded by the vision model to the outputs from comparable human behavioral coding. Our method recognizes children’s microactivities. The timing and number of contact events detected were accurate (96–99

Background: The need to study and understand cumulative impacts, the combined influence of chemical and non-chemical stressors on health and quality of life, is becoming increasingly recognized. The goal of this study is to understand how residents in fenceline communities experience the cumulative impacts of pollution and other non-chemical stressors on their physical and mental health and to develop meaningful policy solutions to mitigate the harms caused by these cumulative burdens. Methods: We used a community-based participatory research (CBPR) approach, partnering with residents in southern Delaware County, PA, experiencing environmental injustice, to design and conduct focus groups. Our focus groups aimed to better understand how residents characterize stressors related to their environmental, physical, and mental health. We used a deductive/inductive hybrid data analysis method to distill the most significant findings from the focus groups. Results: We conducted focus groups with residents (n = 22) of four Southeastern Pennsylvania fenceline municipalities. Participants discussed chemical (e.g., air pollution and odors) and non-chemical stressors (e.g., lack of access to green spaces) influencing their physical and mental health. Participants also described how these stressors are interconnected and worsen their health and quality of life. Participants identified solutions (e.g., policy change and community organizing) to mitigate the most pressing stressors. Discussion: This study is the first in the area to work alongside community investigators to understand how residents in fenceline communities experience cumulative impacts. Our findings were presented to key community stakeholders to inform future advocacy work to mitigate the cumulative burdens faced by these fenceline communities.

Background:Community organizers in Southern Delaware County, PA, expressed a desire to collect comprehensive data on environmental, health, and social conditions in their neighborhoods to inform advocacy efforts to prompt public health action. Methods:Using a community-based participatory research (CBPR) approach, our team of academic and community coinvestigators developed an online community health survey to characterize residents' health concerns and the strengths, burdens, and needs of fenceline communities in Southern Delaware County. We included questions on chemical exposures, sources of pollution, financial stressors, health care, medical conditions, and priorities for policymakers. Results:Participants reported experiencing adverse effects of poor air quality, odors, and noise in their communities. Eighty-six percent of participants reported experiencing at least two nonchemical stressors, such as poor housing conditions, food insecurity, and experiences of racism and discrimination. We found high proportions of reported asthma diagnoses and symptoms in participants and the children living in their households. Symptoms of asthma, depression, and anxiety were more common than clinician diagnoses of these conditions. Participants also commonly reported decreased quality of life or functioning associated with physical and mental health issues. Discussion:Our findings highlight the importance of characterizing chemical and nonchemical stressors among residents in fenceline communities and expanding consideration of health to include acute symptoms, well-being, and quality of life. Our study was strengthened by our CBPR approach. Conclusion:Our work demonstrates the value of assessing cumulative impacts and employing CBPR approaches in fenceline communities.

Carbadox (CBX) is approved for use in swine in the U.S. despite concerns due to its carcinogenicity, and pork containing carcinogenic residues may be entering the food supply. We developed and applied a new method to quantify the carcinogenic CBX residue desoxycarbadox (DCBX) and the noncarcinogenic residue quinoxaline-2-carboxylic acid (QCA) to a variety of retail pork products purchased in the Baltimore, MD, region. We analyzed 33 pork samples from 13 pork producers and did not detect DCBX or QCA in any sample. Information on CBX use was gathered from the integrators; seven (54%) did not respond, one confirmed CBX use, one reported no CBX use, and we could not determine CBX use based on responses from four integrators. While CBX remains in use in the U.S., the application of an analytical method that can detect CBX residues of carcinogenic concern in target edible tissues is necessary to protect consumers.

BACKGROUND:Rising global atmospheric carbon dioxide (CO2) concentrations and surface temperatures could negatively affect rice yields and nutritional quality; however, their effects on arsenic accumulation in paddy rice have not been assessed concurrently. We aimed to assess the impact of increases in CO2 and temperature (individually and in combination) on arsenic concentrations in rice, characterise soil properties that might influence arsenic uptake, and model the associated risks of cancer and other health outcomes due to increased arsenic exposure. METHODS:For this modelling study we performed in-situ multi-varietal trials using Free-Air CO2 Enrichment platforms with and without supplemental temperature to examine the bioaccumulation of arsenic in paddy rice and the underlying biogeochemical mechanisms from 2014 to 2023. We modelled dietary inorganic arsenic exposure and the associated risks of cancer and non-cancer health outcomes via rice consumption for seven of the leading rice-consuming countries in east and southeast Asia. FINDINGS:Concomitant increases in CO2 and temperature resulted in a synergistic increase of inorganic arsenic in rice grain. The observed increase is likely to be related to changes in soil biogeochemistry that favoured reduced arsenic species. Modelled consumption of rice under these conditions resulted in projected increases in inorganic arsenic exposure and lifetime cancer and health risks for multiple Asian countries by 2050. INTERPRETATION:Inorganic arsenic exposure and the associated health consequences might increase in rice grain grown in flooded systems with mid-century climate projections. The current assessment reinforces the urgent need for mitigation of arsenic exposure in rice relative to near-term climate change. FUNDING:National Key Research and Development Program of China, National Natural Science Foundation of China, Key-Area Research and Development Program of Guangdong Province, China, Carbon Peaking and Carbon Neutrality Special Fund for Science and Technology from Nanjing Science and Technology Bureau, Key Research and Development Program of Jiangsu Province, Erdos City Science and Technology Major Project, Science Foundation of the Chinese Academy of Sciences, Carbon Peaking and Carbon Neutrality Special Fund for Science and Technology from Jiangsu Science and Technology Department, and "0-1" Original Innovation Project of the Chinese Academy of Sciences.

Dust ingestion is an important pathway for exposure to environmental chemicals, especially for children. However, estimating infant-specific dust ingestion rates remains challenging. One proposed approach to improve estimates is the identification of novel organic tracers. To help address this challenge, we conducted a nontargeted analysis on dust samples collected from waking and sleeping rooms in infants' homes (n = 30) in the greater Baltimore, MD region, as part of the INnovations to Generate Estimates of children's Soil/dust inTake (INGEST) Study. By leveraging publicly available data from the U.S. Environmental Protection Agency (EPA), including commercial product compositions and chemical functional uses, we showed that many compounds in dust were associated with personal care, cleaning, and consumer products. Most features were detected in both collection rooms in at least one home, but only 16.3% of features were detected in both rooms in all of the homes. Additionally, the relative abundance of features across rooms (i.e., room ratios) within and between homes varied substantially. The high intra- and interhome variability, possibly due to differences in consumer practices among inhabitants, may pose challenges with identifying and implementing an organic tracer for estimating children's dust ingestion rates and need to be rigorously characterized for any candidate.

The Environmental Protection Agency requires public water systems create an annual "Consumer Confidence Report" (CCR) for their customers. CCRs are meant to communicate water quality results, and are claimed to be the "centerpiece" of consumer right-to-know under the Safe Drinking Water Act. However, previous research indicates that CCRs are not understandable to members of the American public. This work analyzes a nationally-representative sample of 60 CCRs, collected from water systems of different sizes, and from communities experiencing various levels of social vulnerability. The content and communication quality of CCRs were both evaluated, and the results were analyzed to determine whether CCR quality varies based on water system size or by the demographic served by the utility. Poorer-quality CCRs were more likely to originate from smaller systems, or those serving vulnerable communities - the same systems that are more likely to experience drinking water violations. Additional legal requirements for CCR content and language could have a marked impact in improving the reports to meet the needs of the American public, by giving underserved communities an important document to use for advocating for themselves - which could promote greater environmental justice in public drinking water.

Microactivity rates, including hand- and object-to-mouth contacts, are inputs for modeling children’s exposure to chemicals in soil and dust and from toys. EPA’s confidence in its current recommended microactivity frequency estimates for use in exposure assessments is low. We aimed to quantify children’s hand- and object-to-mouth microactivities using a novel computer vision method and explored differences by lifestage and fine and gross motor development. We recorded 20-minute videos of 61 children aged 6 to ≤18 months playing in their homes under two play contexts. We employed a novel computer vision approach that uses multiview video to estimate 3D body keypoints and measure hand-to-mouth distances, enabling quantification of each child’s hand-and object-to-mouth contact without the need for human coders. We explored differences in the frequency and duration of microactivity contacts by age and motor development. We observed at least one instance of a microactivity event (i.e., hand- or object-to-mouth contact) among 41 of the 61 participants observed. The median rate of object-to-mouth contacts (23 contacts/hour) was greater than hand-to-mouth contacts (6 contacts/hour). We did not observe significant differences in the frequency of either hand-to-mouth and object-to-mouth contacts by age or motor development, but we did observe greater variation in object-to-mouth contacts than previously reported. The median durations of hand- and object-to-mouth contact were 0.24 min/hour and 1.57 min/hour, respectively. Our observed rates of microactivities are comparable and in some cases, less than the current EPA central tendency estimates recommended for use in risk assessments. Our high-end (95th percentile) estimate for object-to-mouth contacts, however, underscores the need for better characterization of population variability in order to protect the most highly exposed children. We apply a novel computer vision algorithm to quantify the microactivity frequencies and durations of 61 children 6 to ≤18 months old. We examine differences in these frequencies and durations by child lifestage and motor development. Demonstration of this method paves the way for future, larger studies that observe children for longer durations to develop confident estimates of population variability in microactivity behaviors. These and future data could inform analyses in support of the revision of EPA recommendations for children’s soil and dust ingestion rates.

Ethylene oxide ("EtO") is an industrially made volatile organic compound and a known human carcinogen. There are few reliable reports of ambient EtO concentrations around production and end-use facilities, however, despite major exposure concerns. We present in situ, fast (1 Hz), sensitive EtO measurements made during February 2023 across the southeastern Louisiana industrial corridor. We aggregated mobile data at 500 m spatial resolution and reported average mixing ratios for 75 km of the corridor. Mean and median aggregated values were 31.4 and 23.3 ppt, respectively, and a majority (75%) of 500 m grid cells were above 10.9 ppt, the lifetime exposure concentration corresponding to 100-in-one million excess cancer risk (1 x 10(-4)). A small subset (3.3%) were above 109 ppt (1000-in-one million cancer risk, 1 x 10(-3)); these tended to be near EtO-emitting facilities, though we observed plumes over 10 km from the nearest facilities. Many plumes were highly correlated with other measured gases, indicating potential emission sources, and a subset was measured simultaneously with a second commercial analyzer, showing good agreement. We estimated EtO for 13 census tracts, all of which were higher than EPA estimates (median difference of 21.3 ppt). Our findings provide important information about EtO concentrations and potential exposure risks in a key industrial region and advance the application of EtO analytical methods for ambient sampling and mobile monitoring for air toxics.