Abstract  Georgopoulos and Lioy (1994) presented a theoretical framework for exposure analysis, incorporating multiple levels of empirical and mechanistic information while characterizing/reducing uncertainties. The present review summarizes efforts towards implementing that framework, through the development of a mechanistic source-to-dose Modeling ENvironment for TOtal Risks studies (MENTOR), a computational toolbox that provides various modeling and data analysis tools to facilitate assessment of cumulative and aggregate (multipathway) exposures to contaminant mixtures. MENTOR adopts a "Person Oriented Modeling" (POM) approach that can be applied to either specific individuals or to populations/subpopulations of interest; the latter is accomplished by defining samples of "virtual" individuals that statistically reproduce the physiological, demographic, etc., attributes of the populations studied. MENTOR implementations currently incorporate and expand USEPA's SHEDS (Stochastic Human Exposure and Dose Simulation) approach and consider multiple exposure routes (inhalation, food, drinking water intake; non-dietary ingestion; dermal absorption). Typically, simulations involve: (1) characterizing background levels of contaminants by combining model predictions and measurement studies; (2) characterizing multimedia levels and temporal profiles of contaminants in various residential and occupational microenvironments; (3) selecting sample populations that statistically reproduce essential demographics (age, gender, race, occupation, education) of relevant population units (e.g., census tracts); (4) developing activity event sequences for each member of the sample by matching attributes to entries of USEPA's Consolidated Human Activity Database (CHAD); (5) calculating intake rates for the sample population members, reflecting physiological attributes and activities pursued; (6) combining intake rates from multiple routes to assess exposures; (7) estimating target tissue doses with physiologically based dosimetry/toxicokinetic modeling.

Abstract  The International Programme on Chemical Safety (IPCS) Harmonization Project aims to develop consistent principles for risk assessment that are widely accepted around the world. Experts in exposure assessment (the IPCS Harmonization Project Exposure Assessment Working Group) were invited to identify issues that pose barriers to the harmonization of exposure assessment methods and to develop a plan of action. One issue that was identified is the development and application of exposure models in the exposure assessment process. The Working Group therefore designated a subcommittee to develop a state-of-the-science paper on exposure models.

Abstract  OBJECTIVE: Dust control is recommended as one of the cornerstones of controlling childhood lead exposure; however, the effectiveness of dust control has not been demonstrated for children who have low to mild elevations in blood lead (ie, less than 25 micrograms/dL). The objective of this study was to determine whether dust control, as performed by families, had an effect on children's blood lead levels and dust lead levels in children's homes.

DESIGN: Randomized, controlled trial.

SETTING: Community-based trial in Rochester, NY.

PARTICIPANTS: One hundred four children, 12 to 31 months of age at baseline.

INTERVENTION: Families and children were randomized to one of two groups. Families of children in the intervention group received cleaning supplies, information about cleaning areas that are often contaminated with lead, and a cleaning demonstration. Families in the control group received only a brochure about lead poisoning prevention.

OUTCOME MEASURES: Baseline measurements of lead in blood, house dust, soil, water, and paint were taken from both groups. Seven months after enrollment, a second blood lead assay was obtained, and lead levels in household dust were measured. The main outcome measures were change in blood lead levels and dust lead levels by treatment group.

RESULTS: The median blood lead level of children enrolled in the study was 6.7 micrograms/dL (range, 1.7 to 30.6 micrograms/dL). There was no significant difference in the change of children's blood lead levels or dust lead levels by treatment group. The median change in blood lead levels among children in the intervention group was -0.05 micrograms/dL compared with -0.60 micrograms/dL among those in the control group. There also was no significant difference in the change of dust lead by group assignment, although there was a trend toward a significant difference in the percentage of change in dust lead levels on noncarpeted floors, which was greater among houses in the intervention group.

CONCLUSIONS: These data suggest that an intervention that consists only of providing cleaning supplies and a brief description of dust control is not effective at reducing blood lead levels among urban children with low to mild elevations in blood lead levels at a 7-month follow-up.

Abstract  Surveys were conducted in 4 areas in Wales [UK] with differing degrees of environmental Pb. In 2 areas the source of the Pb was traffic and in 1 it was spoil from Pb mining in the past. The 4th area, which served as a control, was a village remote from heavy traffic, industry and Pb mining. Various environmental samples were taken, and children aged 1-3 yr and their mothers were studied. Blood Pb concentrations were raised in the Pb mining area, and within the areas defined by traffic flow the blood Pb concentrations of the mothers showed a gradient. Pica in the children, assessed by a questionnaire, showed no relation with blood Pb, but the amount of Pb removed from the children's hands with wet wipes was an important contributor to blood Pb concentrations.

Abstract  The USDA National Nutrient Database for Standard Reference (SR) is the major source of food composition data in the United States. It provides the foundation for most food composition databases in the public and private sectors. As information is updated, new versions of the database are released. This version, Release 20 (SR20), contains data on 7,519 food items and up to 140 food components. It replaces SR19 issued in August 2006. SR20 includes composition data for all the food groups and nutrients published in the 21 volumes of AAgriculture Handbook 8@ (U.S. Department of Agriculture 1976B92), and its four supplements (U.S. Department of Agriculture 1990B93), which superseded the 1963 edition (Watt and Merrill, 1963). Since 1992, updated data have been published electronically on the USDA Nutrient Data Laboratory (NDL) website. SR20 supersedes all previous releases, including the printed versions, in the event of any differences. With the first release of data from the new Nutrient Databank System (NDBS) in July 2001, formats were changed and fields added to improve the descriptive information for food items and the statistical information about the nutrient values. While data in previous releases have been moved to the new NDBS, they may not have been updated through the complete system. Therefore, many of these new fields contain data only for those items that have been processed through the new NDBS and it will take a number of years before they are populated for most food items in the database. Data have been compiled from published and unpublished sources. Published sources include the scientific and technical literature. Unpublished data include those obtained from the food industry, other government agencies, and research conducted under contracts initiated by USDA Agricultural Research Service (ARS). These analyses are currently conducted under the National Food and Nutrient Analysis Program (NFNAP), in cooperation with the National Cancer Institute and 16 other offices and institutes of the National Institutes of Health (Pehrsson et al., 2000). Data from the food industry represents the nutrient content of a specific food or food product at the time the data is sent to NDL. The values may change due to reformulations or other processing changes by individual companies between the time that SR is released and the next update of the database. Values in the database may be based on the results of laboratory analyses or calculated by using appropriate algorithms, factors, or recipes, as indicated by the source code in the Nutrient Data file. Not every food item contains a complete nutrient profile.

Abstract  This publication contains estimates of food and nutrient intakes by individuals residing in households in the 48 conterminous States and Washington, D.C., based on data from the 1987-88 Nationwide Food Consumption Survey conducted by the U.S. Department of Agriculture. One-day food and nutrient intake data for 10,172 individuals of all ages were collected between April 1987 and August 1988. The data, collected using a 1-day recall in a personal interview, are provided in six tables. Food and nutrient intake data are tabulated for individuals by sex and age, region, income level, and race. For 64 food groups and subgroups, mean quantities of foods eaten per individual in a day and percentages of individuals who reported eating any food from the specified food groups and subgroups are presented. Also presented are tables of the mean intakes of food energy and nutrients; the percentages of total food energy from protein, total fat, fatty acids, and carbohydrate; and nutrient intakes expressed as percentages of the 1989 Recommended Dietary Allowances. Response rates were very low, approximately 31 percent at the individual level, and the possibility of nonresponse bias cannot be disregarded.

Abstract  A Microsoft Windows-based indoor air quality (IAQ) simulation software package is presented. Named Simulation Tool Kit for Indoor Air Quality and Inhalation Exposure, or IAQX for short, this package complements and supplements existing IAQ simulation programs and is designed mainly for advanced users. IAQX version 1.0 consists of five stand-alone simulation programs. A general-purpose simulation program performs multi-zone, multipollutant simulations and allows gas-phase chemical reactions. The other four programs implement fundamentally based models, which are often excluded in the existing IAQ simulation programs. In addition to performing conventional IAQ simulations, which compute the time concentration profile and inhalation exposure, IAQX can estimate the adequate ventilation rate when certain air quality criteria are provided by the user, a unique feature useful for product stewardship and risk management. IAQX will be developed in a cumulative manner and more special-purpose simulation programs will be added to the package in the future.

Abstract  In the Fall of 1985 EPA's Office of Radiation Programs (ORP) initiated a project to develop a formal approach to dealing with uncertainties encountered when estimating and evaluating risks to human health and the environment. Based on a literature review of modeling uncertainty, interviews with ORP technical and management staff, and input from experts on uncertainty analysis, a comprehensive approach was developed. This approach recognizes by design the constraints on budget, time, manpower, expertise, and availability of information often encountered in ''real world'' modeling. It is based on the observation that in practice risk modeling is usually done to support a decision process. As such, the approach focuses on how to frame a given risk modeling problem, how to use that framing to select an appropriate mixture of uncertainty analyses techniques, and how to integrate the techniques into an uncertainty assessment that effectively communicates important information and insight to decision-makers. The approach is presented in this report. Practical guidance on characterizing and analyzing uncertainties about model form and quantities and on effectively communicating uncertainty analysis results is included. Examples from actual applications are presented. (ERA citation 13:047344)

Abstract  Ingestion of soil by young children may be an important source of exposure to environmental contaminants. Estimates of soil ingestion have been made by several studies using trace elements in a mass-balance approach, but differ substantially between studies and trace elements. We conduct a meta-analysis of four major mass-balance soil ingestion studies conducted on children between one and seven in the summer/fall in the northern United States. The analysis takes advantage of primary data from all studies, and provides a more complete description of soil ingestion among children. The meta-analysis uses data based on the two most reliable trace elements, Al and Si, that have passed a screening to identify and exclude measures with a high likelihood of bias. Details are described in a companion paper. The best linear unbiased predictor is used in a mixed model to estimate soil ingestion for study subjects. Overall, 11% of subject-periods are identified as outliers and excluded from the analysis. An analysis on 216 children based on Al and Si as tracer elements indicates that the mean (median) soil ingestion is 26 mg/day (33 mg/day), with the 95th percentile estimated as 79 mg/day. This systematic approach provides more reliable estimates than individual study results. There is some evidence that soil ingestion increases with a child's age, but insufficient data to distinguish soil ingestion by gender.

Abstract  A probabilistic model (SHEDS-Wood) was developed to examine children's exposure and dose to chromated copper arsenate (CCA)-treated wood, as described in Part 1 of this two-part article. This Part 2 article discusses sensitivity and uncertainty analyses conducted to assess the key model inputs and areas of needed research for children's exposure to CCA-treated playsets and decks. The following types of analyses were conducted: (1) sensitivity analyses using a percentile scaling approach and multiple stepwise regression; and (2) uncertainty analyses using the bootstrap and two-stage Monte Carlo techniques. The five most important variables, based on both sensitivity and uncertainty analyses, were: wood surface residue-to-skin transfer efficiency; wood surface residue levels; fraction of hand surface area mouthed per mouthing event; average fraction of nonresidential outdoor time a child plays on/around CCA-treated public playsets; and frequency of hand washing. In general, there was a factor of 8 for the 5th and 95th percentiles and a factor of 4 for the 50th percentile in the uncertainty of predicted population dose estimates due to parameter uncertainty. Data were available for most of the key model inputs identified with sensitivity and uncertainty analyses; however, there were few or no data for some key inputs. To evaluate and improve the accuracy of model results, future measurement studies should obtain longitudinal time-activity diary information on children, spatial and temporal measurements of residue and soil concentrations on or near CCA-treated playsets and decks, and key exposure factors. Future studies should also address other sources of uncertainty in addition to parameter uncertainty, such as scenario and model uncertainty.

Abstract  The 2003 Commercial Buildings Energy Consumption Survey (CBECS) was administered as a computer-assisted personal interview (CAPI) that was programmed using Blaise software. The interview involved many complex skip patterns, driven by different variables such as the type of structure and the building activity.

Abstract  We have developed a modeling and measurement framework for assessing transport of contaminated soils and airborne particulates into a residence, their subsequent distribution indoors via resuspension and deposition processes, and removal by cleaning and building exhalation of suspended particles. The model explicitly accounts for the formation of house dust as a mixture of organic matter (OM) such as shed skin cells and organic fibers, soil tracked-in on footwear, and particulate matter (PM) derived from the infiltration of outdoor air. We derived formulas for use with measurements of inorganic contaminants, crustal tracers, OM, and PM to quantify selected transport parameters. Application of the model to residences in the U.S. Midwest indicates that As in ambient air can account for nearly 60% of the As input to floor dust, with soil track-in representing the remainder. Historic data on Pb contamination in Sacramento, CA, were used to reconstruct sources of Pb in indoor dust, showing that airborne Pb was likely the dominant source in the early 1980s. However, as airborne Pb levels declined due to the phase-out of leaded gasoline, soil resuspension and track-in eventually became the primary sources of Pb in house dust.

Abstract  A critical aspect of air pollution exposure models is the estimation of the air exchange rate (AER) of individual homes, where people spend most of their time. The AER, which is the airflow into and out of a building, is a primary mechanism for entry of outdoor air pollutants and removal of indoor source emissions. The mechanistic Lawrence Berkeley Laboratory (LBL) AER model was linked to a leakage area model to predict AER from questionnaires and meteorology. The LBL model was also extended to include natural ventilation (LBLX). Using literature-reported parameter values, AER predictions from LBL and LBLX models were compared to data from 642 daily AER measurements across 31 detached homes in central North Carolina, with corresponding questionnaires and meteorological observations. Data was collected on seven consecutive days during each of four consecutive seasons. For the individual model-predicted and measured AER, the median absolute difference was 43% (0.17 h(-1)) and 40% (0.17 h(-1)) for the LBL and LBLX models, respectively. Additionally, a literature-reported empirical scale factor (SF) AER model was evaluated, which showed a median absolute difference of 50% (0.25 h(-1)). The capability of the LBL, LBLX, and SF models could help reduce the AER uncertainty in air pollution exposure models used to develop exposure metrics for health studies.

Abstract  The authors explain the ways in which uncertainty is an important factor in the problems of risk and policy analysis. This book outlines the source and nature of uncertainty, discusses techniques for obtaining and using expert judgment, and reviews a variety of simple and advanced methods for analyzing uncertainty.

Abstract  Objectives: This report presents final 2007 data on U.S. deaths, death rates, life expectancy, infant and maternal mortality, and trends by selected characteristics such as age, sex, Hispanic origin, race, marital status, educational attainment, injury at work, state of residence, and cause of death. Methods: Information reported on death certificates, which are completed by funeral directors, attending physicians, medical examiners, and coroners, is presented in descriptive tabulations. The original records are filed in state registration offices. Statistical information is compiled in a national database through the Vital Statistics Cooperative Program of the Centers for Disease Control and Prevention’s National Center for Health Statistics. Causes of death are processed in accordance with the International Classification of Diseases, Tenth Revision. Results: In 2007, a total of 2,423,712 deaths were reported in the United States. The age-adjusted death rate was 760.2 deaths per 100,000 standard population, a decrease of 2.1 percent from the 2006 rate and a record low historical figure. Life expectancy at birth rose 0.2 year, from a 2006 value of 77.7 years to a record 77.9 in 2007. Age-specific death rates decreased for most age groups—15–24, 35–44, 45–54, 55–64, 65–74, 75–84, and 85 and over—and remained unchanged for the age groups of under age 1, 1–4, 5–14, and 25–34. The 15 leading causes of death in 2007 remained the same as in 2006 with the exception of two causes that exchanged ranks. Alzheimer’s disease, the seventh leading cause of death in 2006, became the sixth leading cause in 2007, and Diabetes mellitus, the sixth leading cause in 2006, dropped to the seventh leading cause in 2007. Heart disease and cancer continued to be the leading and second-leading causes of death, respectively, together accounting for almost one-half of all deaths (48.6 percent). The infant mortality rate in 2007 was 6.75 deaths per 1,000 live births. Conclusions: Mortality patterns in 2007, such as the decline in the age-adjusted death rate to a record historical low, were generally consistent with long-term trends. Life expectancy reached a record high in 2007, increasing 0.2 year from 2006.

Abstract  This paper presents a survey and comparative evaluation of methods which have been developed for the determination of uncertainties in accident consequences and probabilities, for use in probabilistic risk assessment. The methods considered are: analytic techniques, Monte Carlo simulation, response surface approaches, differential sensitivity techniques, and evaluation of classical statistical confidence bounds. It is concluded that only the response surface and differential sensitivity approaches are sufficiently general and flexible for use as overall methods of uncertainty analysis in probabilistic risk assessment. The other methods considered, however, are very useful in particular problems.

Abstract  The foods and diets of FDA's Total Diet Study have been revised according to current food consumption patterns. A representative subset of 234 foods, selected from aggregated NFCS and NHANES II data, is collected and analyzed by the Kansas City Field Office Laboratory for 11 essential minerals and more than 120 chemical contaminants. The daily intake by weight of these 234 foods has been extrapolated to represent 100% of the usual diet for eight age-sex groups. These extrapolated food intakes will be used to assess daily contaminant and mineral intakes. The revised food list and diets will be used until the results of another national food consumption survey show the necessity to further revise the diets for the Total Diet Study Program.

Abstract  The paper critiques a 1988 dissertation by Wong (1) of soil pica amongst Institutionalized children on the Island of Jamaica. The Wong dissertation presents the most extensive data yet of soil pica with respect to both numbers of children (six) displaying soil pica and the duration of study (4 months). Amongst children of normal mental capabilities with an average age of 3.1 years, 5 of 24 (20.8%) displayed soil pica behavior (i.e., > 1 g soil Ingested/day) on at least one occasion. In addition, 10.5% of all observations of these 24 children Involved soil Ingestion of > 1 gm/day. Emphasis is given to the Wong dissertation because It has essentially escaped notice amongst those researching and critiquing In the area of soil Ingestion most likely because its emphasis was directed toward exposure to parasites having a life‐cycle stage in soil and not chemical contaminants.

Abstract  California Environmental Protection Agency. In order to evaluate more precisely the potential health risks from air pollution, it is critically important to have accurate estimates of the volume of air breathed (VE) by exposed populations. There is a substantial amount of characteristic VE data available in the literature, but values typically are representative of adult males during rest and in light to moderate activities. This is due in part to difficulties in the direct measurement of VE in free-ranging people, which requires portable respirometers that can restrict normal performance of some common activities. Thus, VE for free-ranging activity has usually been estimated from unobtrusive heart rate (HR) measurements in individuals whose VE to HR relationship response to varied intensities of cycle ergometer or treadmill exercise had been established in the laboratory. However, it is not known how accurately VE is predicted in the field when using this method. To resolve this problem, both VE and HR must be measured simultaneously in the field across a wide range of free-ranging activities. The primary purposes of this research were to 1) identify mean values and ranges of VE for specific activities and populations, and 2) develop equations which would permit VE predictions based on known activity and population characteristics. The subject population utilized in this study comprised 160 normally active individuals of both genders, and of varied age (6-77 years) and ethnicity. In addition, 40 children (6-12 years) were recruited for data validation and 12 young children (3-5 years) were identified as subjects for pilot testing purposes. Subjects completed resting (lying, sitting and standing) and active (walking and running) laboratory protocols, and usually one or more field protocols (i.e., play, car driving/riding, car maintenance, yardwork, housework, mowing and/or woodworking). Collected laboratory data included steady-state measurements of VE, HR, breathing frequency (fB) and oxygen consumption (VO2), while data collection in the field was limited to the continuous measurement of VE, HR and fB during each protocol. Resting responses for the children's groups revealed no significant gender differences and those for the adult groups demonstrated minimal age-group differences; therefore, resting data were combined into children, adult female and adult male groups. Heart rate and VE responses were poorly correlated in all resting postures for each group. However, fB was a better predictor for VE, with body surface area (BSA) being an important additive variable in multiple regression equations. Very similar observations were obtained from the cross-validation children's group. Regression analysis revealed higher r values for walking and running protocols than for field protocols, which were higher than for resting protocols. Typically, HR was poorly correlated with VE except during active laboratory protocols, whereas fB and BSA were variables that better predicted VE across all types of activities and population groups. The inclusion of all three variables (BSA, HR and fB) in multiple regression equations, generally provided the most accurate predictions of Vs across groups and activity types. The lower precision of prediction for active field protocols than for laboratory walking and running protocols was at~ibuxed primarily to the wide variety of individual activities and intensity of effort during field protocols. Using the mean VE values obtained for each population group and activity, field protocols were categorized into one of the following: sedentary activity, and light or moderate exercise. For the children's groups, spontaneous play protocols were identified as moderate exercise. Car driving/riding was classified as sedentary activity for both genders. Car maintenance for the male adult group was categorized as light exercise, while their VE responses to woodworking, mowing and yardwork protocols were class

Abstract  A standardized, reproducible method of surrogate dermal monitoring was devised to supplement knowledge of the potential transfer of pesticide residues from floor surfaces to persons in contact with the floor. This device was a 12 kg. foam-covered rolling cylinder equipped with stationary handles. The device was rolled over a cotton cloth (the actual collection media) placed over carpet to be sampled. This method transfers between 1 and 3 percent of the potential available pesticide material from nylon carpeting to the collection media. Transfer from carpet to cotton cloth correlates highly with transfer to cotton clothing worn by persons exercising on the carpet.

Abstract  A wide variety of surface materials in buildings can release organic compounds. Examples include building materials, furnishings, maintenance materials, clothing, and paper products. These sources contribute substantially to the hundreds of organic compounds that have been measured in indoor air. Their emissions have been directly connected to complaints of odors or hyperreactivity and are presumed to contribute to the problems in many "sick buildings" where the cause of complaints is uncertain. Significant progress has been made in the past decade in developing procedures for measuring emissions from such materials, in controlled experiments where factors affecting emission rates can be determined and quantified. Emissions data are still limited but are being accumulated gradually by research groups in Europe and North America. It is clear from the recent data gathered in research and modeling studies that one of the most effective ways to limit indoor concentrations of organic compounds is to limit the content of volatile compounds in materials that are used in buildings. Limiting the original residual content of such compounds in the materials, or conditioning such materials prior to use in buildings, or (perhaps) conditioning such materials in place before occupancy of a new or renovated building, are most likely to prevent excessive indoor concentrations. If emissions testing and product certification procedures are available and there is sufficient market demand for low-emitting materials caused by indoor air quality concerns, significant reductions of indoor concentrations of vapor-phase organic compounds could be achieved within the next decade.