A major objective of the National Human Exposure Assessment Survey (NHEXAS) performed in Arizona was to conduct residential environmental and biomarker measurements of selected pesticides (chlorpyrifos, diazinon), volatile organic compounds (VOCs; benzene, toluene, trichloroethene, formaldehyde, 1,3-butadiene), and metals for total human exposure assessments. Both personal (e.g., blood, urine, dermal wipes, 24 h duplicate diet) and microenvironmental (e.g., indoor and outdoor air, house dust, foundation soil) samples were collected in each home in order to describe individual exposure via ingestion, inhalation, and dermal pathways, and to extrapolate trends to larger populations. This paper is a preliminary report of only the microenvironmental and dermal wipe data obtained for the target pesticides and VOCs, and provides comparisons with results from similar studies. Evaluations of total exposure from all sources and pathways will be addressed in future papers. The pesticides and VOCs all showed log-normal distributions of concentrations in the Arizona population sampled, and in most cases were detected with sufficient frequency to allow unequivocal description of the concentration by media at the 90th, 75th, and 50th (median) percentiles. Those combinations of pollutant and media, in which a large fraction of the measurements were below the detection limit of the analysis method used, included trichloroethene, 1,3-butadiene, and formaldehyde in outdoor air; chlorpyrifos and diazinon in outdoor air; and diazinon in dermal and window sill wipes. In general, indoor air concentrations were higher than outdoor air concentrations for all VOCs and pesticides investigated, and VOC levels were in good agreement with levels reported in other studies. In addition, the agreement obtained between co-located VOC samplers indicated that the low-cost diffusional badges used to measure concentrations are probably adequate for use in future monitoring studies. For the pesticides, the median levels found in indoor samples agreed well with other studies, although the levels corresponding to the upper 0.1-1% of the population were considerably higher than levels reported elsewhere, with indoor air levels as high as 3.3 and 20.5 microg/m3 for chlorpyrifos and diazinon, respectively. These data showed excellent correlation (Pearson and Spearman correlation coefficients of 0.998 and 0.998, respectively) between chlorpyrifos in indoor air and in the corresponding dermal wipes, and relatively poor correlation between chlorpyrifos in dust (microg/g or microg/ml) and dermal wipes (Pearson=0.055 microg/g and 0.015 microg/m2; Spearman=0.644 microg/g and 0.578 microg/m2). These data suggest the importance of dermal penetration of semi-volatiles as a route of residential human exposure.

Air Pollutants↗

PubMedDate not supplied

Evaluations of primary metals from NHEXAS Arizona: distributions and preliminary exposures. National Human Exposure Assessment Survey.

NHEXAS AZ is a multimedia, multipathway exposure assessment survey designed to evaluate metals and other analytes. This paper reports the analyte-specific concentration distributions in each of the media examined (air, soil, house dust, food, beverage, and water), for various methodologies used (inductively coupled plasma-atomic emission spectroscopy and hydride generation-atomic absorption spectroscopy). Results are reported for the five primary metals (Pb, As, Cd, Cr, and Ni). Ingestion was the most important pathway of exposure. Metal concentrations in air were very low (ng/m3) and found only above the 90th percentile. Metals were commonly found in house dust and soil. Exposure transfer coefficients minimize the importance of this component for those over the age of 6 years. When ranked by exposure, food, beverage, and water appeared to be the primary contributors of metal exposure in NHEXAS AZ. For instance, at the 90th percentile, Pb was undetected in air, found at 131 and 118 microg/m3 in floor dust and soil, respectively, and measured at 16 microg/kg in food, 7.1 microg/kg in beverage, and 2.0 and 1.3 microg/l in drinking and tap water, respectively. We calculated preliminary estimates of total exposure (microg/day) for each participant and examined them independently by age, gender, and ethnicity as reported by the subjects in the NHEXAS questionnaire. At the 90th percentile for Pb, total exposures were 64 microg/day across all subjects (n=176); adult men (n=55) had the greatest exposure (73 microg/day) and children (n=35) the least (37 microg/day). Hispanics (n=54) had greater exposure to Pb (68 microg/day) than non-Hispanics (n=119; 50 microg/day), whereas non-Hispanics had greater exposure for all other metals reported. These results have implications related to environmental justice. The NHEXAS project provides information to make informed decisions for protecting and promoting appropriate public health policy.

Adolescent↗

PubMedDate not supplied

The National Human Exposure Assessment Survey (NHEXAS) study in Arizona--introduction and preliminary results.

The objective of the National Human Exposure Assessment Survey (NHEXAS) in Arizona is to determine the multimedia distribution of total human exposure to environmental pollutants in the classes of metals, pesticides, and volatile organic compounds (VOCs) for the population of Arizona. This was accomplished by studying a probability-based sample of the total population in Arizona with a nested design for the different stages of sampling (954 Stage I, 505 Stage II, and 179 Stage III participants). This report compares the study population demographics with those from the U.S. Census and provides preliminary data on the distributions of the example pollutant for each class, lead for metals, chlorpyrifos for pesticides, and benzene for metals. The probability-based sample age and gender demographics compare reasonably well with the Census data (1990 Census and 1996 Census Estimate). The race/ethnicity compared less well with 21% Hispanics in the 1996 Census Estimate and 42% Hispanics in the entire NHEXAS-Arizona sample and 30% Hispanics as Stage III participants for this study. The chemical analyses of the various media (yard soil, foundation soil, house dust, indoor air, outdoor air, drinking water, food, and beverage) show generally low levels of the representative pollutants. The 50th percentiles of the distributions are generally near or below the analytical detection limits, and applicable Federal action limits were rarely exceeded.

Adolescent↗

PubMedDate not supplied

On predicting multi-route and multimedia residential exposure to chlorpyrifos and diazinon.

This paper formulates regression models and examines their ability to associate exposures to chlorpyrifos and diazinon in residences with information obtained from questionnaires and environmental sampling of the National Human Exposure Assessment Survey Arizona (NHEXAS-AZ) database. A knowledge-based list of 29 potential exposure determinants was assembled from information obtained from six questionnaires administered in the course of the study. This list was used to select the independent variables of each model statistically and electronically. Depending on the data type of dependent and independent variables, four classes of regression models were developed to determine desired associations. Route-specific exposures were estimated using the indirect method of exposure estimation and measurements from the NHEXAS-AZ field study. The stepwise procedure was used to construct regression models. Significance level at P=0.10 was used for entry and retention of independent variables in a model. Twelve significant regression models were formulated to quantify associations among exposures and other variables in the NHEXAS-AZ database. Route-specific exposures to pesticides associate significantly with questionnaire-based variables such as preparation of pesticides, use of pesticide inside the house, and income level; and with concentration variables in three media: dermal wipe, sill wipe, and indoor air. Models formulated in this study may be used to estimate exposures to each of the pesticides. Yet, the use of these models must incorporate clear statements of the assumptions made in the formulation as well as the coefficient of determination and the confidence and prediction intervals of the dependent variable.

Activities of Daily Living↗

PubMedDate not supplied

Aerosol usage and respiratory symptoms.

In an epidemiological study of 3,485 selected individuals in Tucson, aerosol usage appears to be correlated to prevalence of respiratory symptoms. This effect persists after adjusting age and smoking to the prevalence rates for symptoms and appears to exist for specific types of aerosols. Further specification and clarification of these relationships are needed in the epidemiological survey. Critical evaluation within in vitro and in vivo models is of great importance. It is concluded that the propellants, the ingredients of the application, and the combination elements in different circumstances must be studied toxicologically to determine the mechanism and extent of specific actions on organisms.

Adolescent↗

PubMedDate not supplied

Relation of peak expiratory flow rates and symptoms to ambient ozone.

The temporal association between peak expiratory flow rates (PEFRs) and ambient ozone (O3) was studied in a group of 287 children and 523 nonsmoking adults in Tucson. In children, noon PEFRs were decreased on days when there was a higher O3 concentration; children with physician-confirmed asthma experienced the greatest decrease in noon PEFR. Evening PEFR levels were also significantly related to O3 in children, especially asthmatics. Among adults, evening PEFRs were decreased in asthmatics who spent more time outdoors on days when O3 levels were higher. After we adjusted for covariates, significant effects of interactions of 8-h O3 levels with particulate matter (PM10) and temperature on daily PEFR were found. There was some overnight effect of 8-h O3 on morning PEFRs. In general, the respiratory response to low-level ambient O3 is acute, occurs more in asthmatics, and increases as temperature and PM10 increase.

Adolescent↗

PubMedDate not supplied

Indoor Air '90: health effects associated with indoor air contaminants.

Explore the source record for details and available documents.

Air Pollution, Indoor↗

PubMedDate not supplied

Multipollutant exposures and health responses to particulate matter.

Epidemiological methods provide opportunities to study interactions of pollutants in complex environments. During the study of health and the environment and the evaluation of particulate matter in Tucson, we found that type, location, and temporality of particulate matter exposures were critical with respect to the various interactions that related to health effects. Indoor particulate matter interacted with other components of particulate matter found in tobacco smoke, as evidenced by lung function. The interaction of environmental tobacco smoke with indoor formaldehyde caused various symptoms. Other interactions occurred between indoor and outdoor forms of particulate matter, which caused symptoms in some of the subjects.

Air Pollutants↗

PubMedDate not supplied

Population-based exposure measurements in Arizona: a phase I field study in support of the National Human Exposure Assessment Survey.

The objective of this proposed Phase I field study is to determine the distributions of total human exposures to multimedia pollutants in the classes of metals, pesticides, and volatile organic compounds (VOCs). This will be achieved by studying a proportion-based sample of the total population in Arizona with a nested design for the different stages of sampling. Specific objectives are: (1) to document the occurrence, distribution, and determinants of total exposures in the general population; (2) to characterize the 90th percentiles of total exposures to each pollutant; (3) to monitor geographic and temporal trends of the multimedia exposures; (4) to evaluate the different media, personal, time-activity, and geographical factors that contribute to current total exposure; (5) to evaluate biomarkers in blood and urine for the target pollutants; (6) to perform evaluations of relationships between exposure reports, environmental measurements, and biomarkers of the target pollutants; (7) to predict total exposures; and (8) to assess total exposures in minority and disadvantaged subsets of the population. The latter is particularly feasible in Arizona due to the large proportions of such population subgroups. The proportionate-based population sampling of households within blocks will occur in Stage 1; the target is 1,200 such households. They will be interviewed utilizing National Human Exposure Assessment Survey (NHEXAS) questionnaires. In Stage 2, additional questionnaires will be completed; environmental sampling will take place in 450-900 households representatively selected from the respondents. Environmental sampling will include: metals in dust, soil, outside air, and some tap water; pesticides in dust, soil, and some tap water; total VOCs in air. In Stage 3, a subset of representative households will be reevaluated for metals, pesticides, and VOCs using methods with greater resolution and reliability; subjects in these households will be asked to complete questionnaires and provide biological samples. Follow-up temporal evaluations will be performed in a randomly selected subset of homes evaluated during this stage.

Arizona↗