Construction of residential histories to estimate long-term environmental exposures in the California Teachers Study cohort.

Environmental epidemiologic studies using geospatial data often estimate exposure at a participant's residence upon enrollment, but mobility during the exposure period can lead to misclassification. We aimed to mitigate this issue by constructing residential histories for participants in the California Teachers Study through follow-up (1995-2018). Address records have been collected from the US Postal Service, LexisNexis, Experian, and California Cancer Registry. We identified records of the same address based on geo-coordinate distance (≤250 m) and street name similarity. We consolidated addresses, prioritizing those confirmed by participants during follow-up questionnaires, and estimating the duration lived at each address using dates associated with records (e.g., date-first-seen). During 23 years of follow-up, about half of participants moved (48%, including 14% out-of-state). We observed greater mobility among younger women, Hispanic/Latino women, and those in metropolitan and lower socioeconomic status areas. The cumulative proportion of in-state movers remaining eligible for analysis was 21%, 32%, and 41% at 5, 10, and 20 years post enrollment, respectively. Using self-reported information collected 10 years after enrollment, we correctly identified 94% of movers and 95% of non-movers as having moved or not moved from their enrollment address. This dataset provides a foundation for estimating long-term environmental exposures in diverse epidemiologic studies in this cohort. IMPACT: Our efforts in constructing residential histories for California Teachers Study participants through follow-up (1995-2018) benefit future environmental epidemiologic studies. Address availability during the exposure period can mitigate misclassification due to residential changes, especially when evaluating long-term exposures and chronic health outcomes. This can reduce differential misclassification among more mobile subgroups, including younger women and those from lower socioeconomic and urban areas. Our approach to consolidating addresses from multiple sources showed high accuracy in comparison to self-reported residential information. The residential dataset produced from this analysis provides a valuable tool for future studies, ultimately enhancing our understanding of environmental health impacts.

Prediagnostic serum concentrations of per- and polyfluoroalkyl substances and risk of papillary thyroid cancer in the Finnish Maternity Cohort.

Human exposure to per- and polyfluoroalkyl substances (PFAS) occurs globally through contaminated food, dust, and drinking water. Studies of PFAS and thyroid cancer have been limited. We conducted a nested case-control study of prediagnostic serum levels of 19 PFAS and papillary thyroid cancer (400 cases, 400 controls) in the Finnish Maternity Cohort (pregnancies 1986-2010; follow-up through 2016), individually matched on sample year and age. We used conditional logistic regression to estimate odds ratios (OR) and 95% confidence intervals (CI) for log2 transformed and categorical exposures, overall and stratified by calendar period, birth cohort, and median age at diagnosis. We adjusted for other PFAS with Spearman correlation rho = 0.3-0.6. Seven PFAS, including perfluoroctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), N-ethyl-perfluorooctane sulfonamidoacetic acid (EtFOSAA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluorohexane sulfonic acid (PFHxS) were detected in >50% of women. These PFAS were not associated with risk of thyroid cancer, except for PFHxS, which was inversely associated (OR log2 = 0.82, 95% CI: 0.70-0.97). We observed suggestive but imprecise increased risks associated with PFOA, PFOS, and EtFOSAA for those diagnosed at ages <40 years, whereas associations were null or inverse among those diagnosed at 40+ years (P-interaction: .02, .08, .13, respectively). There was little evidence of other interactions. These results show no clear association between PFAS and papillary thyroid cancer risk. Future work would benefit from evaluation of these relationships among those with higher exposure levels and during periods of early development when the thyroid gland may be more susceptible to environmental harms.

Maternal serum concentrations of per- and polyfluoroalkyl substances and childhood acute lymphoblastic leukemia.

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are widespread and environmentally persistent chemicals with immunotoxic properties. Children are prenatally exposed through maternal transfer of PFAS to cord blood, but no studies have investigated the relationship with childhood leukemia. METHODS: We measured maternal serum levels of 19 PFAS in first-trimester samples collected in 1986-2010 and evaluated associations with acute lymphoblastic leukemia (ALL) in full-term offspring (<15 years) for 400 cases and 400 controls in the Finnish Maternity Cohort, matched on sample year, mother's age, gestational age, birth order, and child's sex. We analyzed continuous and categorical exposures, estimating odds ratios (OR) and 95% confidence intervals (CI) via conditional logistic regression adjusted for maternal smoking and correlated PFAS (ρ ≥ ±0.3). We also stratified by calendar period, mean diagnosis age, and the child's sex. RESULTS: N­methyl­perfluorooctane sulfonamidoacetic acid (MeFOSAA) was associated with ALL in continuous models (per each doubling in levels: ORperlog2=1.22, CI = 1.07-1.39), with a positive exposure-response across categories (OR>90th percentile=2.52, CI = 1.33-4.78; p-trend = 0.01). While we found no relationship with perfluorooctane sulfonic acid (PFOS) overall, an association was observed in samples collected 1986-1995, when levels were highest (median = 17.9 µg/L; ORperlog2=4.01, CI = 1.62-9.93). A positive association with perfluorononanoic acid was suggested among first births (p-interaction = 0.06). The MeFOSAA association was mainly limited to children diagnosed before age 5 (p-interaction = 0.02). We found no consistent patterns of association with other PFAS, nor differences by sex. CONCLUSIONS: These novel data offer evidence of a relationship between some PFAS and risk of the most common childhood cancer worldwide, including associations with the highest levels of PFOS and with a precursor, MeFOSAA.

Geospatial determinants of maternal and child exposure to fine particulate matter in Kintampo, Ghana: Levels within the household and community, by surrounding building density and near roadways.

BACKGROUND: Personal exposure to fine particulate matter (PM2.5) from household air pollution is well-documented in sub-Saharan Africa, but spatiotemporal patterns of exposure are poorly characterized. OBJECTIVE: We used paired GPS and personal PM2.5 data to evaluate changes in exposure across location-time environments (e.g., household and community, during cooking and non-cooking hours), building density and proximity to roadways. METHODS: Our study included 259 sessions of geolocated, gravimetrically-calibrated one-minute personal PM2.5 measurements from participants in the GRAPHS Child Lung Function Study. The household vicinity was defined using a 50-meter buffer around participants' homes. Community boundaries were developed using a spatial clustering algorithm applied to an open-source dataset of building footprints in Africa. For each GPS location, we estimated building density (500 m buffer) and proximity to roadways (100 m buffer). We estimated changes in PM2.5 exposure by location (household, community), time of day (morning/evening cooking hours, night), building density, and proximity to roadways using linear mixed effect models. RESULTS: Relative to nighttime household exposure, PM2.5 exposure during evening cooking hours was 2.84 (95%CI = 2.70-2.98) and 1.80 (95%CI = 1.54-2.10) times higher in the household and community, respectively. Exposures were elevated in areas with the highest versus lowest quartile of building density (FactorQ1vsQ4 = 1.60, 95%CI = 1.42-1.80). The effect of building density was strongest during evening cooking hours, and influenced levels in both the household and community (31% and 65% relative increase from Q1 to Q4, respectively). Being proximal to a trunk, tertiary or track roadway increased exposure by a factor of 1.16 (95%CI = 1.07-1.25), 1.68 (95%CI = 1.45-1.95) and 1.27 (95%CI = 1.06-1.53), respectively. IMPACT: Household air pollution from cooking with solid fuels in sub-Saharan Africa is a major environmental concern for maternal and child health. Our study advances previous knowledge by quantifying the impact of household cooking activities on air pollution levels in the community, and identifying two geographic features, building density and roadways, that contribute to maternal and child daily exposure. Household cooking contributes to higher air pollution levels in the community especially in areas with greater building density. Findings underscore the need for equitable clean household energy transitions that reach entire communities to reduce health risks from household and outdoor air pollution.

Ethylene oxide emissions and incident breast cancer and non-Hodgkin lymphoma in a US cohort.

BACKGROUND: Ethylene oxide (EtO) is a carcinogenic gas used in chemical production and to sterilize medical equipment that has been linked to risk of breast and lymphohematopoietic cancers in a small number of occupational studies. We investigated the relationship between environmental EtO exposure and risk of these cancers. METHODS: Using the US Environmental Protection Agency's Toxics Release Inventory, we estimated historical exposures for National Institutes of Health-AARP Diet and Health Study participants enrolled in 1995-1996. We constructed 2 metrics at 3, 5, and 10 km: 1) distance between residences and EtO-emitting facilities, weighted by the proportion of time the home was downwind of each facility, and 2) distance-weighted, wind direction-adjusted average airborne emissions index (AEI=∑[lbs EtO/km2]). We estimated risk (hazard ratio [HR], 95% confidence interval [CI]) of incident breast cancer (in situ and invasive) among postmenopausal women (n = 173 670) overall and by tumor estrogen receptor status and non-Hodgkin lymphoma in the full cohort (n = 451 945). RESULTS: We observed an increased risk of breast cancer associated with EtO-emitting facilities within 10 km (HR[≤10vs>10] = 1.05, 95% CI = 1.00 to 1.10) that appeared stronger for in situ (HR[≤10vs>10] = 1.13, 95% CI = 1.00 to 1.27) than invasive (HR[≤10vs>10] = 1.03, 95% CI = 0.97 to 1.09) disease. Risk of breast cancer in situ was also increased in the top AEI quartiles, and associations weakened with larger distances (HR[Q4vs0] = 1.60, 95% CI = 0.98 to 2.61; HR[Q4vs0] = 1.28, 95% CI = 0.92 to 1.79; HR[Q4vs0] = 1.25, 95% CI = 1.02 to 1.53 at 3, 5, and 10 km, respectively). No differences in breast cancer risk were observed by estrogen receptor status. We found no clear pattern of increased non-Hodgkin lymphoma risk. CONCLUSIONS: A novel potential association between EtO emissions and risk of in situ, but not invasive, breast cancer warrants additional evaluation.

Juxtaposition of intensive agriculture, vulnerable aquifers, and mixed chemical/microbial exposures in private-well tapwater in northeast Iowa.

In the United States and globally, contaminant exposure in unregulated private-well point-of-use tapwater (TW) is a recognized public-health data gap and an obstacle to both risk-management and homeowner decision making. To help address the lack of data on broad contaminant exposures in private-well TW from hydrologically-vulnerable (alluvial, karst) aquifers in agriculturally-intensive landscapes, samples were collected in 2018-2019 from 47 northeast Iowa farms and analyzed for 35 inorganics, 437 unique organics, 5 in vitro bioassays, and 11 microbial assays. Twenty-six inorganics and 51 organics, dominated by pesticides and related transformation products (35 herbicide-, 5 insecticide-, and 2 fungicide-related), were observed in TW. Heterotrophic bacteria detections were near ubiquitous (94 % of the samples), with detection of total coliform bacteria in 28 % of the samples and growth on at least one putative-pathogen selective media across all TW samples. Health-based hazard index screening levels were exceeded frequently in private-well TW and attributed primarily to inorganics (nitrate, uranium). Results support incorporation of residential treatment systems to protect against contaminant exposure and the need for increased monitoring of rural private-well homes. Continued assessment of unmonitored and unregulated private-supply TW is needed to model contaminant exposures and human-health risks.

Residential proximity to dioxin emissions and risk of breast cancer in the sister study cohort.

Some dioxins are carcinogenic, but few studies have investigated the relationship between ambient polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/F) and risk of breast cancer. We evaluated associations between proximity-based residential exposure to industrial emissions of PCDD/F and breast cancer risk in a large U.S. cohort. Sister Study participants at enrollment (2003-2009) were followed for incident breast cancer through September 2018. After restricting to participants with ≥10 years of residential history prior to enrollment (n = 35,908), we generated 10-year distance- and toxic equivalency quotient (TEQ)-weighted average emissions indices (AEI [g TEQ/km2]) within 3, 5, or 10 km of participants' residences, overall and by facility type. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between AEI quartiles (vs. zero AEI) and risk of breast cancer [invasive or ductal carcinoma in situ]. There were 2670 incident breast cancer cases over 11 years (median) of follow-up. Breast cancer risk was increased for those in the highest quartile [Q] of AEI exposure within 3 km (HRQ4:1.18, 95% CI: 0.99,1.40, Ptrend = 0.03). The HR was higher for the 10-year AEI at 3 km from municipal solid waste facilities (HR ≥ median.vs.0:1.50, 95% CI: 0.98, 2.29; Ptrend = 0.07). Risk was higher among ever smokers (vs. never smokers) in the top quartile of the 3 km AEI (HRQ4:1.41, 95% CI:1.12,1.77, Ptrend = 0.003; Pinteraction = 0.03) and higher risk for ER negative tumors was suggested (HRQ4:1.47, 95% CI: 0.95, 2.28, Ptrend = 0.07, Pheterogeneity = 0.17). Our findings suggest that residential exposure to PCDD/F emissions may confer an increased risk of breast cancer.

Outdoor light at night and risk of endometrial cancer in the NIH-AARP diet and health study.

PURPOSE: Outdoor light at night (LAN) can result in circadian disruption and hormone dysregulation and is a suspected risk factor for some cancers. Our study is the first to evaluate the association between LAN and risk of endometrial cancer, a malignancy with known relationship to circulating estrogen levels. METHODS: We linked enrollment addresses (1996) for 97,677 postmenopausal women in the prospective NIH-AARP cohort to satellite imagery of nighttime radiance to estimate LAN exposure. Multivariable Cox models estimated hazard ratios (HR) and 95% confidence intervals (95% CI) for LAN quintiles and incident endometrial cancer overall (1,669 cases) and endometrioid adenocarcinomas (991 cases) through follow-up (2011). We tested for interaction with established endometrial cancer risk factors. RESULTS: We observed no association for endometrial cancer overall (HRQ1vsQ5 0.92; 95% CI 0.78-1.08; p trend = 0.67) or endometrioid adenocarcinoma (HRQ1vsQ5 1.01; 95% CI 0.82-1.24; p trend = 0.36). Although body mass index and menopause hormone therapy were both associated with risk, there was no evidence of interaction with LAN (p interactions = 0.52 and 0.50, respectively). CONCLUSION: Our study did not find an association between outdoor LAN and endometrial cancer risk, but was limited by the inability to account for individual-level exposure determinants. Future studies should consider approaches to improve characterization of personal exposures to light.

Drinking Water Disinfection Byproducts, Ingested Nitrate, and Risk of Endometrial Cancer in Postmenopausal Women.

BACKGROUND: Disinfection byproducts (DBPs) and N-nitroso compounds (NOC), formed endogenously after nitrate ingestion, are suspected endometrial carcinogens, but epidemiological studies are limited. OBJECTIVES: We investigated the relationship of these exposures with endometrial cancer risk in a large prospective cohort. METHODS: Among postmenopausal women in the Iowa Women's Health Study cohort, we evaluated two major classes of DBPs, total trihalomethanes (TTHM) and five haloacetic acids (HAA5), and nitrate-nitrogen (NO3-N) in public water supplies (PWS) in relation to incident primary endometrial cancer (1986-2014). For women using their PWS >10y at enrollment (n=10,501; cases=261), we computed historical averages of annual concentrations; exposures were categorized into quantiles and when possible ≥95th percentile. We also computed years of PWS use above one-half the U.S. maximum contaminant level (>½ MCL; 40µg/L TTHM; 30µg/L HAA5; 5mg/L NO3-N). Dietary nitrate/nitrite intakes were estimated from a food frequency questionnaire. We estimated hazard ratios (HR) and 95% confidence intervals (CI) via Cox models adjusted for age, endometrial cancer risk factors [e.g., body mass index, hormone replacement therapy (HRT)], and mutually adjusted for DBPs or NO3-N. We evaluated associations for low-grade (cases=99) vs. high-grade (cases=114) type I tumors. We assessed interactions between exposures and endometrial cancer risk factors and dietary factors influencing NOC formation. RESULTS: Higher average concentrations of DBPs (95th percentile: TTHM ≥93µg/L, HAA5 ≥49µg/L) were associated with endometrial cancer risk (TTHM: HR95vsQ1=2.19, 95% CI: 1.41, 3.40; HAA5: HR95vsQ1=1.84, 95% CI: 1.19, 2.83; ptrend<0.01). Associations were similarly observed for women greater than median years of PWS use with levels >½ MCL, in comparison with zero years (TTHM: HR36+vs0y=1.61, 95% CI: 1.18, 2.21; HAA5: HR38+vs0y=1.85, 95% CI: 1.31, 2.62). Associations with DBPs appeared stronger for low-grade tumors (TTHM: HRQ4vsQ1=2.12, 95% CI: 1.17, 3.83; p-trend=0.008) than for high-grade tumors (TTHM: HRQ4vsQ1=1.40, 95% CI: 0.80, 2.44; p-trend=0.339), but differences were not statistically significant (p-heterogeneity=0.43). Associations with TTHM were stronger among ever HRT users than non-HRT users (p-interaction<0.01). We observed no associations with NO3-N in drinking water or diet. DISCUSSION: We report novel associations between the highest DBP levels and endometrial cancer for our Iowa cohort that warrant future evaluation. https://doi.org/10.1289/EHP10207.

Evaluation of a commercial database to estimate residence histories in the los angeles ultrafines study.

BACKGROUND: Commercial databases can be used to identify participant addresses over time, but their quality and impact on environmental exposure assessment is uncertain. OBJECTIVE: To evaluate the performance of a commercial database to find residences and estimate environmental exposures for study participants. METHODS: We searched LexisNexis® for participant addresses in the Los Angeles Ultrafines Study, a prospective cohort of men and women aged 50-71 years. At enrollment (1995-1996) and follow-up (2004-2005), we evaluated attainment (address found for the corresponding time period) and match rates to survey addresses by participant characteristics. We compared geographically-referenced predictors and estimates of ultrafine particulate matter (UFP) exposure from a land use regression model using LexisNexis and survey addresses at enrollment. RESULTS: LexisNexis identified an address for 69% of participants at enrollment (N = 50,320) and 95% of participants at follow-up (N = 24,432). Attainment rate at enrollment modestly differed (≥5%) by age, smoking status, education, and residential mobility between surveys. The match rate at both survey periods was high (82-86%) and similar across characteristics. When using LexisNexis versus survey addresses, correlations were high for continuous values of UFP exposure and its predictors (rho = 0.86-0.92). SIGNIFICANCE: Time period and population characteristics influenced the attainment of addresses from a commercial database, but accuracy and subsequent estimation of specific air pollution exposures were high in our older study population.

Impact of residential mobility on estimated environmental exposures in a prospective cohort of older women.

Longitudinal studies of environmental hazards often rely on exposure estimated at the participant's enrollment residence. This could lead to exposure misclassification if participants move over time. METHODS: We evaluated residential mobility in the Iowa Women's Health Study (age 55-69 years) over 19 years of follow-up (1986-2004). We assessed several environmental exposures of varying spatial scales at enrollment and follow-up addresses. Exposures included average nitrate concentrations in public water supplies, percent of agricultural land (row crops and pasture/hay) within 750 m, and the presence of concentrated animal feeding operations within 5 km. In comparison to gold standard duration-based exposures averaged across all residences, we evaluated the sensitivity and specificity of exposure metrics and attenuation bias for a hypothetical nested case-control study of cancer, which assumed participants did not move from their enrollment residence. RESULTS: Among 41,650 participants, 32% moved at least once during follow-up. Mobility was predicted by working outside the home, being a former/current smoker, having a higher education level, using a public drinking water supply, and town size of previous residence. Compared with duration-based exposures, the sensitivity and specificity of exposures at enrollment ranged from 94% to 99% and 97% to 99%, respectively. A hypothetical true odds ratio of 2.0 was attenuated 8% for nitrate, 9%-10% for agricultural land, and 6% for concentrated animal feeding operation exposures. CONCLUSIONS: Overall, we found low rates of mobility and mobility-related exposure misclassification in the Iowa Women's Health Study. Misclassification and attenuation of hypothetical risk estimates differed by spatial variability and exposure prevalence.

Pilot study of global endocrine disrupting activity in Iowa public drinking water utilities using cell-based assays.

Some anthropogenic substances in drinking water are known or suspected endocrine disrupting compounds (EDCs), but EDCs are not routinely measured. We conducted a pilot study of 10 public drinking water utilities in Iowa, where common contaminants (e.g., pesticides) are suspected EDCs. Raw (untreated) and finished (treated) drinking water samples were collected in spring and fall and concentrated using solid phase extraction. We assessed multiple endocrine disrupting activities using novel mammalian cell-based assays that express nuclear steroid receptors (aryl hydrocarbon [AhR], androgenic [AR], thyroid [TR], estrogenic [ER] and glucocorticoid [GR]). We quantified each receptor's activation relative to negative controls and compared activity by season and utility/sample characteristics. Among 62 samples, 69% had AhR, 52% AR, 3% TR, 2% ER, and 0% GR activity. AhR and AR activities were detected more frequently in spring (p =0 .002 and < 0.001, respectively). AR activity was more common in samples of raw water (p =0 .02) and from surface water utilities (p =0 .05), especially in fall (p =0 .03). Multivariable analyses suggested spring season, surface water, and nitrate and disinfection byproduct concentrations as determinants of bioactivity. Our results demonstrate that AR and AhR activities are commonly found in Iowa drinking water, and that their detection varies by season and utility/sample characteristics. Screening EDCs with cell-based bioassays holds promise for characterizing population exposure to diverse EDCs mixtures.

Impact of geo-imputation on epidemiologic associations in a study of outdoor air pollution and respiratory hospitalization.

Imputation of missing spatial attributes in health records may facilitate linkages to geo-referenced environmental exposures, but few studies have assessed geo-imputation impacts on epidemiologic inference. We imputed patient Census tracts in a case-crossover analysis of fine particulate matter (PM2.5) and respiratory hospitalizations in New York State (2000-2005). We observed non-significantly higher PM2.5 exposures, high accuracy of binary exposure assignment (89 to 99%), and marginally different hazard ratios (HRs) (-0.2 to 0.7%). HR differences were greater in urban versus rural areas. Given its efficiency and nominal influence on accuracy of exposure classification and measures of association, geo-imputation is a candidate method to address missing spatial attributes for health studies.

Insulin Resistance in Healthy U.S. Adults: Findings from the National Health and Nutrition Examination Survey (NHANES).

BACKGROUND: Insulin is fundamental in two conditions that are epidemic in the United States and globally: obesity and type II diabetes. Given insulin's established mechanistic involvement in energy balance and glucose tolerance, we examined its relationship to common health-related endpoints in a large population-based sample. METHODS: The National Health and Nutrition Examination Survey is a cross-sectional study that uses a complex multistage probability design to obtain a representative sample of the United States population. Adult participants were included from 8 successive 2-year data waves (1999-2014), including 9,224 normal individuals, 7,699 prediabetic, and 3,413 diabetic subjects. The homeostatic model for insulin resistance (HOMA-IR) was available for 20,336 participants and its relationship with demographic, anthropometric, and clinical data was analyzed. We examined the relationship of HOMA-IR to 8 groups of outcome variables: general health, anthropometric/metabolic [waist size, body mass index (BMI)], cardiovascular (blood pressure), lipid [triglycerides, high-density lipoprotein (HDL)], hepatic [alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT)], hematologic [white blood cells (WBC), hemoglobin (Hgb), platelets], inflammatory (C-reactive protein), and nutritional (vitamins D and C, serum folate, and pyridoxine) variables. RESULTS: HOMA-IR was generally strongly, monotonically, and highly significantly associated with adjusted outcomes in normal subjects, although clinical laboratory values were generally within normal bounds across insulin quartiles. In the normal subset, the odds ratio and 95% confidence interval for a quartile change in HOMA-IR for obesity (BMI > 30) was 3.62 (3.30-3.97), and for the highest quintile for the triglyceride/HDL the ratio was 2.00 (1.77-2.26), for GGT it was 1.40 (1.24-1.58), and for WBC it was 1.28 (1.16-1.40). The relationship of HOMA-IR to the various outcomes was broadly similar to that observed in prediabetics and diabetics with a few exceptions. CONCLUSIONS: HOMA-IR levels in a large sample of normal individuals are associated with poorer general health and adverse changes across a wide range of markers. A similar pattern of alterations is observed in prediabetic and diabetic samples. IMPACT: Clinically, checking insulin levels may be helpful to identify patients that merit further observation and are candidates for early interventions.

The landscape of enteric pathogen exposure of young children in public domains of low-income, urban Kenya: The influence of exposure pathway and spatial range of play on multi-pathogen exposure risks.

Young children are infected by a diverse variety of enteric pathogens in low-income, high-burden countries. Little is known about which conditions pose the greatest risk for enteric pathogen exposure and infection. Young children frequently play in residential public areas around their household, including areas contaminated by human and animal feces, suggesting these exposures are particularly hazardous. The objective of this study was to examine how the dose of six types of common enteric pathogens, and the probability of exposure to one or multiple enteric pathogens for young children playing at public play areas in Kisumu, Kenya is influenced by the type and frequency of child play behaviors that result in ingestion of soil or surface water. Additionally, we examine how pathogen doses and multi-pathogen exposure are modified by spatial variability in the number of public areas children are exposed to in their neighborhood. A Bayesian framework was employed to obtain the posterior distribution of pathogen doses for a certain number of contacts. First, a multivariate mixed effects tobit model was used to obtain the posterior distribution of pathogen concentrations, and their interdependencies, in soil and surface water, based upon empirical data of enteric pathogen contamination in three neighborhoods of Kisumu. Then, exposure doses were estimated using behavioral contact parameters from previous studies and contrasted under different exposure conditions. Pathogen presence and concentration in soil varied widely across local (< 25 meter radius area) and neighborhood-level scales, but pathogens were correlated among distinct surface water samples collected near to each other. Multi-pathogen exposure of children at public play areas was common. Pathogen doses and the probability of multi-pathogen ingestion increased with: higher frequency of environmental contact, especially for surface water; larger volume of soil or water ingested; and with play at multiple sites in the neighborhood versus single site play. Child contact with surface water and soil at public play areas in their neighborhood is an important cause of exposure to enteric pathogens in Kisumu, and behavioral, environmental, and spatial conditions are determinants of exposure.

Where Children Play: Young Child Exposure to Environmental Hazards during Play in Public Areas in a Transitioning Internally Displaced Persons Community in Haiti.

Globally, gastrointestinal (GI) infections by enteric pathogens are the second-leading cause of morbidity and mortality in children under five years of age (≤5 years). While GI pathogen exposure in households has been rigorously examined, there is little data about young children's exposure in public domains. Moreover, public areas in low-income settings are often used for other waste disposal practices in addition to human feces, such as trash dumping in areas near households. If young children play in public domains, they might be exposed to interrelated and highly concentrated microbial, chemical, and physical hazards. This study performed structured observations at 36 public areas in an internally displaced persons community that has transitioned into a formal settlement in Haiti. We documented how often young children played in public areas and quantified behaviors that might lead to illness and injury. Children ≤5 years played at all public sites, which included infants who played at 47% of sites. Children touched and mouthed plastic, metal and glass trash, food and other objects from the ground, ate soil (geophagia) and drank surface water. They also touched latrines, animals, animal feces and open drainage canals. Hand-to-mouth contact was one of the most common behaviors observed and the rate of contact significantly differed among developmental stages (infants: 18/h, toddlers: 11/h and young children: 9/h), providing evidence that children could ingest trace amounts of animal/human feces on hands that may contain GI pathogens. These findings demonstrate that water, sanitation and hygiene interventions could be more effective if they consider exposure risks to feces in public domains. Furthermore, this research highlights the need for waste-related interventions to address the broader set of civil conditions that create unsafe, toxic and contaminated public environments where young children play.

Investigation of Acute Pulmonary Deficits Associated with Biomass Fuel Cookstove Emissions in Rural Bangladesh.

The use of solid biomass fuels in cookstoves has been associated with chronic health impacts that disproportionately affect women worldwide. Solid fuel stoves that use wood, plant matter, and cow dung are commonly used for household cooking in rural Bangladesh. This study investigates the immediate effects of acute elevated cookstove emission exposures on pulmonary function. Pulmonary function was measured with spirometry before and during cooking to assess changes in respiratory function during exposure to cookstove emissions for 15 females ages 18-65. Cookstove emissions were characterized using continuous measurements of particulate matter (PM2.5-aerodynamic diameter <2.5 µm) concentrations at a 1 s time resolution for each household. Several case studies were observed where women ≥40 years who had been cooking for ≥25 years suffered from severe pulmonary impairment. Forced expiratory volume in one second over forced vital capacity (FEV1/FVC) was found to moderately decline (p = 0.06) during cooking versus non-cooking in the study cohort. The study found a significant (α < 0.05) negative association between 3- and 10-min maximum PM2.5 emissions during cooking and lung function measurements of forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and FEV1/FVC obtained during cooking intervals. This study found that exposure to biomass burning emissions from solid fuel stoves- associated with acute elevated PM2.5 concentrations- leads to a decrease in pulmonary function, although further research is needed to ascertain the prolonged (e.g., daily, for multiple years) impacts of acute PM2.5 exposure on immediate and sustained respiratory impairment.