Drinking water and health assessment in a Northern Arizona community.

Arizona is a mineral rich state that relies on a mix of surface and ground water supplies for drinking water requirements. Small, rural water systems relying on groundwater frequently encounter elevated metal(loid) measures, particularly inorganic arsenic (As +3, +5). Such contaminant occurrences can be associated with adverse health outcomes including cancers. The Hopi Environmental Health Project examined drinking water quality and water consumption behaviors from 76 homes on Hopi lands over a four-year period. Water samples were analyzed for 28 elements and compared to US Environmental Protection Agengy (EPA) maximum contaminant levels (MCL). Only municipal/piped water had a mean arsenic concentration (11.01 µg/L) exceeding the MCL (10.0 µg/L). All other water types and elements occurred below MCL when detected. A lifetime cancer and hazard quotient associated with arsenic consumption through each water type was performed and piped/municipal water was found to carry the greatest risks (9.96 cases per 10,000 people). Results from this study showed the potential for multiple contaminants to be present in drinking water from Hopi lands and the need for further health assessment of routine exposure to low doses of contaminant mixtures through drinking water.

A meta-analysis of sunburn and basal cell carcinoma risk.

Basal cell carcinoma (BCC) is the most common cancer in the United States. Sunburn is a modifiable risk factor for BCC. The objective of this project was to synthesize research on BCC and sunburn to quantify the impact and severity of sunburn at different life stages on BCC risk in the general population. A systematic literature search of four electronic databases was conducted and data were extracted by two independent reviewers using standardized forms. Data from 38 studies were pooled using both dichotomous and dose-response meta-analytic methods. BCC risk increased with ever experiencing a sunburn in childhood (OR=1.43, 95% CI: 1.19, 1.72) and with ever experiencing a sunburn in life (OR= 1.40, 95% CI: 1.02, 1.45). Every five sunburns experienced per decade in childhood increased BCC risk by 1.86 (95% CI: 1.73, 2.00) times. Every five sunburns experienced per decade in adulthood increased BCC risk by 2.12 (95% CI: 1.75, 2.57) times and every five sunburns per decade of life increased BCC risk by 1.91 (95% CI: 1.42, 2.58) times. The data on sunburn exposure and BCC show that an increase in number of sunburns at any age increased the risk of BCC. This may inform future prevention efforts.

Sampling Low Air Pollution Concentrations at a Neighborhood Scale in a Desert U.S. Metropolis with Volatile Weather Patterns.

BACKGROUND: Neighborhood-scale air pollution sampling methods have been used in a range of settings but not in low air pollution airsheds with extreme weather events such as volatile precipitation patterns and extreme summer heat and aridity-all of which will become increasingly common with climate change. The desert U.S. metropolis of Tucson, AZ, has historically low air pollution and a climate marked by volatile weather, presenting a unique opportunity. METHODS: We adapted neighborhood-scale air pollution sampling methods to measure ambient NO2, NOx, and PM2.5 and PM10 in Tucson, AZ. RESULTS: The air pollution concentrations in this location were well below regulatory guidelines and those of other locations using the same methods. While NO2 and NOx were reliably measured, PM2.5 measurements were moderately correlated with those from a collocated reference monitor (r = 0.41, p = 0.13), potentially because of a combination of differences in inlet heights, oversampling of acutely high PM2.5 events, and/or pump operation beyond temperature specifications. CONCLUSION: As the climate changes, sampling methods should be reevaluated for accuracy and precision, especially those that do not operate continuously. This is even more critical for low-pollution airsheds, as studies on low air pollution concentrations will help determine how such ambient exposures relate to health outcomes.

Age and Cohort Trends of Malignant Melanoma in the United States.

The incidence of malignant melanoma in the United States is increasing, possibly due to changes in ultraviolet radiation (UVR) exposure due to lifestyle or increased awareness and diagnosis of melanoma. To determine if more recent birth cohorts experience higher rates of melanoma as they age, we examined age and birth cohort trends in the United States stratified by anatomic site and cancer type (in situ vs. malignant) of the melanoma diagnosed from 1975-2017. Poisson regression of cutaneous melanoma cases per population for 1975-2017 from the Surveillance, Epidemiology, and End Results (SEER) cancer registries was used to estimate age adjusted incidence for five-year birth cohorts restricted to Whites, ages 15-84. The rate of melanoma incidence across birth cohorts varies by anatomic site and sex. Melanomas at all anatomic sites continue to increase, except for head and neck melanomas in men. Much of the increase in malignant melanoma is driven by cases of thin (<1.5 mm) lesions. While increased skin exams may contribute to the increased incidence of in situ and thin melanoma observed across birth cohorts, the shifts in anatomic site of highest melanoma incidence across birth cohorts suggest changes in UVR exposure may also play a role.

Household and behavioral determinants of indoor PM2.5 in a rural solid fuel burning Native American community.

Indoor and outdoor concentrations of PM2.5 were measured for 24 h during heating and non-heating seasons in a rural solid fuel burning Native American community. Household building characteristics were collected during the initial home sampling visit using technician walkthrough questionnaires, and behavioral factors were collected through questionnaires by interviewers. To identify seasonal behavioral factors and household characteristics associated with indoor PM2.5 , data were analyzed separately by heating and non-heating seasons using multivariable regression. Concentrations of PM2.5 were significantly higher during the heating season (indoor: 36.2 µg/m3 ; outdoor: 22.1 µg/m3 ) compared with the non-heating season (indoor: 14.6 µg/m3 ; outdoor: 9.3 µg/m3 ). Heating season indoor PM2.5 was strongly associated with heating fuel type, housing type, indoor pests, use of a climate control unit, number of interior doors, and indoor relative humidity. During the non-heating season, different behavioral and household characteristics were associated with indoor PM2.5 concentrations (indoor smoking and/or burning incense, opening doors and windows, area of surrounding environment, building size and height, and outdoor PM2.5 ). Homes heated with coal and/or wood, or a combination of coal and/or wood with electricity and/or natural gas had elevated indoor PM2.5 concentrations that exceeded both the EPA ambient standard (35 µg/m3 ) and the WHO guideline (25 µg/m3 ).

Inflammation biomarkers associated with arsenic exposure by drinking water and respiratory outcomes in indigenous children from three Yaqui villages in southern Sonora, México.

Environmental arsenic exposure in adults and children has been associated with a reduction in the expression of club cell secretory protein (CC16) and an increase in the expression of matrix metalloproteinase-9 (MMP-9), both biomarkers of lung inflammation and negative respiratory outcomes. The objectives of this study were to determine if the levels of serum CC16 and MMP-9 and subsequent respiratory infections in children are associated with the ingestion of arsenic by drinking water. This cross-sectional study included 216 children from three Yaqui villages, Potam, Vicam, and Cocorit, with levels of arsenic in their ground water of 70.01 ± 21.85, 23.3 ± 9.99, and 11.8 ± 4.42 µg/L respectively. Total arsenic in water and urine samples was determined by inductively coupled plasma/optical emission spectrometry. Serum was analyzed for CC16 and MMP-9 using ELISA. The children had an average urinary arsenic of 79.39 µg/L and 46.8 % had levels above of the national concern value of 50 µg/L. Increased arsenic concentrations in drinking water and average daily arsenic intake by water were associated with decreased serum CC16 levels (ß = - 0.12, 95% CI - 0.20, - 0.04 and ß = - 0.10, 95% CI - 0.18, - 0.03), and increased serum MMP-9 levels (ß = 0.35, 95% CI 0.22, 0.48 and ß = 0.29, 95% CI 0.18, 0.40) at significant levels (P < 0.05). However, no association was found between levels of these serum biomarkers and urinary arsenic concentrations. In these children, reduced serum CC16 levels were significantly associated with increased risk of respiratory infections (OR = 0.34, 95% CI 0.13, 0.90). In conclusion, altered levels of serum CC16 and MMP-9 in the children may be due to the toxic effects of arsenic exposure through drinking water.

Imputation methods for addressing missing data in short-term monitoring of air pollutants.

Monitoring of environmental contaminants is a critical part of exposure sciences research and public health practice. Missing data are often encountered when performing short-term monitoring (<24 h) of air pollutants with real-time monitors, especially in resource-limited areas. Approaches for handling consecutive periods of missing and incomplete data in this context remain unclear. Our aim is to evaluate existing imputation methods for handling missing data for real-time monitors operating for short durations. In a current field-study, realtime PM2.5 monitors were placed outside of 20 households and ran for 24-hours. Missing data was simulated in these households at four consecutive periods of missingness (20%, 40%, 60%, 80%). Univariate (Mean, Median, Last Observation Carried Forward, Kalman Filter, Random, Markov) and multivariate time-series (Predictive Mean Matching, Row Mean Method) methods were used to impute missing concentrations, and performance was evaluated using five error metrics (Absolute Bias, Percent Absolute Error in Means, R2 Coefficient of Determination, Root Mean Square Error, Mean Absolute Error). Univariate methods of Markov, random, and mean imputations were the best performing methods that yielded 24-hour mean concentrations with the lowest error and highest R2 values across all levels of missingness. When evaluating error metrics minute-by-minute, Kalman filters, median, and Markov methods performed well at low levels of missingness (20-40%). However, at higher levels of missingness (60-80%), Markov, random, median, and mean imputation performed best on average. Multivariate methods were the worst performing imputation methods across all levels of missingness. Imputation using univariate methods may provide a reasonable solution to addressing missing data for short-term monitoring of air pollutants, especially in resource-limited areas. Further efforts are needed to evaluate imputation methods that are generalizable across a diverse range of study environments.

Comparison of Perceived and Observed Hand Hygiene Compliance in Healthcare Workers in MERS-CoV Endemic Regions.

This study investigated healthcare workers' perceptions of hand hygiene practices by comparing personal reports, as assessed by questionnaires, to direct observations of the workers' hand hygiene practices. The study employed a cross-sectional research design. Observations were made using a 16-item checklist, based on three sources: Centers for Disease Control and Prevention (CDC), World Health Organization (WHO), and Boyce and Pittet's guidelines of hand hygiene. The checklist was used for both direct-observation and self-reported data collection purposes. Pearson correlation and Multivariate Analysis of Covariance (MANCOVA) were utilized to statistically determine the relationship between healthcare workers' reports of hand hygiene practices and observed hand hygiene behaviors. The study was conducted in the outpatient examination rooms and emergency departments of three types of hospitals in the Eastern region of Saudi Arabia where Middle East respiratory syndrome coronavirus (MERS-CoV) is endemic and is observed in routine cases and outbreaks. The total sample size included 87 physicians and nurses recruited while on duty during the scheduled observation periods, with each healthcare worker being observed during individual medical examinations with at least three patients. No statistically significant correlations between the healthcare workers' perceptions of hand hygiene practices and healthcare workers' actual behaviors were evident. Based on the self-report questionnaires, significant differences were found between physicians' and nurses' hand hygiene practices reports. Healthcare workers clearly understand the importance of careful hand hygiene practices, but based on researchers' observations, the medical personnel failed to properly implement protocol-driven hand hygiene applications. However, the significant differences between physicians' and nurses' self-reports suggest further inquiry is needed to fully explore these discrepancies.

Nutrients in one-carbon metabolism and urinary arsenic methylation in the National Health and Nutrition Examination Survey (NHANES) 2003-2004.

Exposure to inorganic arsenic (inAs), a potent toxicant, occurs primarily through ingestion of food and water. The efficiency with which it is methylated to mono and dimethyl arsenicals (MMA and DMA) affects toxicity. Folate, vitamins B12 and B6 are required for 1C metabolism, and studies have found that higher levels of these nutrients increase methylation capacity and are associated with protection against adverse health effects from inAs, especially in undernourished populations. Our aim was to determine whether 1C-related nutrients are associated with greater inAs methylation capacity in a general population sample with overall adequate nutrition and low levels of As exposure. Univariate and multivariable regression models were used to evaluate the relationship of dietary and blood nutrients to urinary As methylation in the National Health and Nutrition Examination Survey (NHANES) 2003-2004. Outcome variables were the percent of the sum of inAs and methylated As species (inAs+MMA+DMA) excreted as inAs, MMA, and DMA, and the ratio of MMA:DMA. In univariate models, dietary folate, vitamin B6 and protein intake were associated with lower urinary inAs% and greater DMA% in adults (≥18years), with similar trends in children (6-18). In adjusted models, vitamin B6 intake (p=0.011) and RBC folate (p=0.036) were associated with lower inAs%, while dietary vitamin B12 was associated with higher inAs% (p=0.002) and lower DMA% (p=0.030). Total plasma homocysteine was associated with higher MMA% (p=0.004) and lower DMA% (p=0.003), but not with inAs%; other blood nutrients showed no association with urinary As. Although effect size is small, these findings suggest that 1C nutrients can influence inAs methylation and potentially play an indirect role in reducing toxicity in a general population sample.

Relation of dietary inorganic arsenic to serum matrix metalloproteinase-9 (MMP-9) at different threshold concentrations of tap water arsenic.

Arsenic (As) exposure is associated with cancer, lung and cardiovascular disease, yet the mechanisms involved are not clearly understood. Elevated matrix metalloproteinase-9 (MMP-9) levels are also associated with these diseases, as well as with exposure to water As. Our objective was to evaluate the effects of dietary components of inorganic As (iAs) intake on serum MMP-9 concentration at differing levels of tap water As. In a cross-sectional study of 214 adults, dietary iAs intake was estimated from 24-h dietary recall interviews using published iAs residue data; drinking and cooking water As intake from water samples and consumption data. Aggregate iAs intake (food plus water) was associated with elevated serum MMP-9 in mixed model regression, with and without adjustment for covariates. In models stratified by tap water As, aggregate intake was a significant positive predictor of serum MMP-9 in subjects exposed to water As≤10 µg/l. Inorganic As from food alone was associated with serum MMP-9 in subjects exposed to tap water As≤3 µg/l. Exposure to iAs from food and water combined, in areas where tap water As concentration is ≤10 µg/l, may contribute to As-induced changes in a biomarker associated with toxicity.

Environmental arsenic exposure and serum matrix metalloproteinase-9.

The objective of this study was to evaluate the relationship between environmental arsenic exposure and serum matrix metalloproteinase (MMP)-9, a biomarker associated with cardiovascular disease and cancer. In a cross-sectional study of residents of Arizona, USA (n=215) and Sonora, Mexico (n=163), drinking water was assayed for total arsenic, and daily drinking water arsenic intake was estimated. Urine was speciated for arsenic, and concentrations were adjusted for specific gravity. Serum was analyzed for MMP-9 using ELISA. Mixed model linear regression was used to assess the relation among drinking water arsenic concentration, drinking water arsenic intake, urinary arsenic sum of species (the sum of arsenite, arsenate, monomethylarsonic acid and dimethylarsinic acid), and MMP-9, controlling for autocorrelation within households. Drinking water arsenic concentration and intake were positively associated with MMP-9, both in crude analysis and after adjustment for gender, country/ethnicity, age, body mass index, current smoking, and diabetes. Urinary arsenic sum of species was positively associated with MMP-9 in multivariable analysis only. Using Akaike's Information Criterion, arsenic concentration in drinking water provided a better fitting model of MMP-9 than either urinary arsenic or drinking water arsenic intake. In conclusion, arsenic exposure evaluated using all three exposure metrics was positively associated with MMP-9.

Binational arsenic exposure survey: methodology and estimated arsenic intake from drinking water and urinary arsenic concentrations.

The Binational Arsenic Exposure Survey (BAsES) was designed to evaluate probable arsenic exposures in selected areas of southern Arizona and northern Mexico, two regions with known elevated levels of arsenic in groundwater reserves. This paper describes the methodology of BAsES and the relationship between estimated arsenic intake from beverages and arsenic output in urine. Households from eight communities were selected for their varying groundwater arsenic concentrations in Arizona, USA and Sonora, Mexico. Adults responded to questionnaires and provided dietary information. A first morning urine void and water from all household drinking sources were collected. Associations between urinary arsenic concentration (total, organic, inorganic) and estimated level of arsenic consumed from water and other beverages were evaluated through crude associations and by random effects models. Median estimated total arsenic intake from beverages among participants from Arizona communities ranged from 1.7 to 14.1 µg/day compared to 0.6 to 3.4 µg/day among those from Mexico communities. In contrast, median urinary inorganic arsenic concentrations were greatest among participants from Hermosillo, Mexico (6.2 µg/L) whereas a high of 2.0 µg/L was found among participants from Ajo, Arizona. Estimated arsenic intake from drinking water was associated with urinary total arsenic concentration (p < 0.001), urinary inorganic arsenic concentration (p < 0.001), and urinary sum of species (p < 0.001). Urinary arsenic concentrations increased between 7% and 12% for each one percent increase in arsenic consumed from drinking water. Variability in arsenic intake from beverages and urinary arsenic output yielded counter intuitive results. Estimated intake of arsenic from all beverages was greatest among Arizonans yet participants in Mexico had higher urinary total and inorganic arsenic concentrations. Other contributors to urinary arsenic concentrations should be evaluated.

Socio-Environmental Health Analysis in Nogales, Sonora, Mexico.

In Nogales, Sonora, Mexico, some neighborhoods, or colonias, have intermittent delivery of water through pipes from the city of Nogales's municipal water-delivery system while other areas lack piped water and rely on water delivered by truck or pipas. This research examined how lifestyles, water quality, and potential disease response, such as diarrhea, differs seasonally from a colonia with access to piped water as opposed to one using alternative water-delivery systems. Water samples were collected from taps or spigots at homes in two Nogales colonias. One colonia reflected high socio-environmental conditions where residents are supplied with municipal piped water (Colonia Lomas de Fatima); the second colonia reflected low socio-environmental conditions, lacking access to piped water and served by pipas (Colonia Luis Donaldo Colosio). A survey was developed and implemented to characterize perceptions of water quality, health impacts, and quality of life. Water samples were analyzed for microbial and inorganic water-quality parameters known to impact human health including, Escherichia coli (E. coli), total coliform bacteria, arsenic, and lead. A total of 21 households agreed to participate in the study (14 in Colosio and 7 in Fatima). In both colonias metal concentrations from water samples were all well below the United States Environmental Protection Agency's (US EPA's) maximum contaminant levels. E. coli concentrations exceeded the US EPA's drinking-water standard in Colosio but not Fatima. Total coliform bacteria were present in over 50 % of households in both colonias. Microbial contamination was significantly higher in the summer than in the winter in both colonias. Resulting analysis suggests that residents in colonias without piped water are at a greater risk of gastrointestinal illness from consumption of compromised drinking water. Our survey corroborated reports of gastrointestinal illness in the summer months but not in the winter. Chloride was found to be significantly greater in Colosio (median 29.2 mg/L) although still below the US EPA's maximum contaminant levels of 250 mg/L. Ongoing binational collaboration can promote mechanisms to improve water quality in cities located in the US-Mexico border.

Landscape-epidemiological study design to investigate an environmentally based disease.

Cost-effective approaches for identifying and enrolling subjects in community-based epidemiological studies face many challenges. Additional challenges arise when a neighborhood scale of analysis is required to distinguish between individual- and group-level risk factors with strong environmental determinants. A stratified, two-stage, cross-sectional, address-based telephone survey of Greater Tucson, Arizona, was conducted in 2002-2003. Subjects were recruited from direct marketing data at neighborhood resolution using a geographic information system (GIS). Three geomorphic strata were divided into two demographic units. Households were randomly selected within census block groups, selected using the probability proportional to size technique. Purchased direct marketing lists represented 45.2% of Census 2000 households in the surveyed block groups. Survey design effect (1.6) on coccidioidomycosis prevalence (88 per 100,000 per year) was substantially reduced in four of the six strata (0.3-0.9). Race-ethnicity was more robust than age and gender to compensate for significant selection bias using poststratification. Clustered, address-based telephone surveys provide a cost-effective, valid method for recruiting populations from address-based lists using a GIS to design surveys and population survey statistical methods for analysis. Landscape ecology provides effective methods for identifying scales of analysis and units for stratification that will improve sampling efficiency when environmental variables of interest are strong predictors.

A risk factor study of coccidioidomycosis by controlling differential misclassifications of exposure and susceptibility using a landscape ecology approach.

State-reported coccidioidomycosis cases in Arizona have dramatically increased since 1997, raising concerns about a possible epidemic, its cause, and associated risk factors, including spatio-temporal differences in susceptibility and exposure. This stratified, two-stage, cross-sectional study evaluates inherent, socio-economic, and environmental risk factors of coccidioidomycosis from information collected during an address-based telephone survey of 5460 households containing 14,105 individuals in greater Tucson, Arizona. Three geomorphic and two demographic strata controlled for differences in group-level exposures and susceptibility, and assured recruitment of a minority population. Logistic regression of self-reported cases indicates that location of residence by geomorphic and demographic strata was a risk factor that confounded the associations of coccidioidomycosis with age, race-ethnicity, and educational attainment. The risk due to age is more evenly distributed across the population than bivariate results when individual- and group-level exposure and susceptibility factors are controlled. Similarly the association for being Hispanic decreased from strong bivariate 0.28 odds ratio to a weak multivariate 0.75. Location of residence confounded the risk due to race-ethnicity and was an effect modifier of risk due to age. Differential misclassification of exposure to Coccidioides spores and susceptibility to coccidioidomycosis was reduced through landscape stratification by demographics and geomorphic types. Landscape epidemiological studies of diseases with strong environmental and demographic determinants can reduce residual confounding and account for spatial and temporal differences between neighborhoods and at broader scales.

The effects of organophosphate pesticide exposure on Hispanic children's cognitive and behavioral functioning.

OBJECTIVE: This study investigates the effects of Organophosphate (OP) pesticides exposure on the cognitive and behavioral functioning of Hispanic children living in an agricultural community. METHODS: Forty-eight children were administered a battery of cognitive measures, and their parents and teachers completed behavior rating scales. Children provided a urine sample for analysis of OP pesticides metabolites. RESULTS: All children had a detectable level of at least one OP pesticide metabolite. Higher OP pesticide metabolite concentration levels were significantly correlated with poorer performance on some subtests of the Wisconsin Card Sorting Test. However, the significance of this association was dependent upon the inclusion of two samples with noticeable higher OP pesticide metabolite concentration levels. CONCLUSIONS: Short-term OP pesticide exposure seems to have deleterious effects on children's speed of attention, sequencing, mental flexibility, visual search, concept formation, and conceptual flexibility. This study is among a relatively small number of studies investigating an extremely complex problem. Limitations and suggestions for future studies are discussed.

Exposure assessment in the National Children's Study: introduction.

The science of exposure assessment is relatively new and evolving rapidly with the advancement of sophisticated methods for specific measurements at the picogram per gram level or lower in a variety of environmental and biologic matrices. Without this measurement capability, environmental health studies rely on questionnaires or other indirect means as the primary method to assess individual exposures. Although we use indirect methods, they are seldom used as stand-alone tools. Analyses of environmental and biologic samples have allowed us to get more precise data on exposure pathways, from sources to concentrations, to routes, to exposure, to doses. They also often allow a better estimation of the absorbed dose and its relation to potential adverse health outcomes in individuals and in populations. Here, we make note of various environmental agents and how best to assess exposure to them in the National Children's Study--a longitudinal epidemiologic study of children's health. Criteria for the analytical method of choice are discussed with particular emphasis on the need for long-term quality control and quality assurance measures.

Assessment of respiratory symptoms and asthma prevalence in a U.S.-Mexico border region.

The authors studied children who were 10-12 yr of age and who resided in sister cities in a U.S.-Mexico border region to determine the prevalence of asthma and respiratory symptoms. The relationship of symptoms to ambient levels of particulate matter less than 10 microm in diameter (PM10), and to several indoor environmental conditions, was assessed. The study was conducted in the border cities of Ambos Nogales (Nogales, Arizona [United States], and Nogales, Sonora [Mexico]). At the beginning of the 11-wk study, during the autumn of 1996, 631 students and their parents completed baseline questionnaires. While in school, the children completed daily symptom diaries and daily peak expiratory flow maneuvers. PM10 values and daily temperatures were also measured. The authors found that the prevalence of self-reported asthma among 5th-grade students was comparable on both sides of the border (i.e., 7.6% on the Arizona side and 6.9% on the Sonora side). Wheezing was a frequent complaint (29.5-35.6%), as was cough (16.8-29.6%). Smoking in the home was common on both sides of the border, and it was associated with a greater occurrence of self-reported asthma and respiratory complaints. Increased respiratory symptoms were also associated with increased ambient PM10 levels. The prevalence of respiratory symptoms such as wheezing and frequent cough among all children in this study, combined with the limitations inherent in self-reporting, suggest that asthma may actually be more prevalent than has been previously reported.

House dust and inorganic urinary arsenic in two Arizona mining towns.

Residents of copper mining and smelting towns may have increased risk of arsenic exposure from elevated arsenic contained in environmental media. To determine the relation of arsenic in house dust to inorganic urinary arsenic concentrations, a door-to-door survey was conducted in Hayden and Winkelman, Arizona. A total of 122 households (404 individuals) participated; 85 provided dust samples. Urine was collected at first morning void and analyzed for total and speciated arsenic. Speciation of arsenic was performed in samples with total arsenic above 10 micro g/l (N=106). The generalized estimating equation was used to determine the relation between urinary and house dust arsenic concentrations, allowing adjustment for the correlation of measurements obtained from the same home. Seafood consumption during the past 3 days and smoking contributed significantly to inorganic urinary arsenic, after adjusting for age and gender. Arsenic in house dust was not significantly associated with inorganic urinary arsenic measurements in this population.