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  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  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  The public depends on competent risk assessment from the federal government and the scientific community to grapple with the threat of pollution. When risk reports turn out to be overblown--or when risks are overlooked--public skepticism abounds. This comprehensive and readable book explores how the U.S. Environmental Protection Agency (EPA) can improve its risk assessment practices, with a focus on implementation of the 1990 Clean Air Act Amendments. With a wealth of detailed information, pertinent examples, and revealing analysis, the volume explores the "default option" and other basic concepts. It offers two views of EPA operations: The first examines how EPA currently assesses exposure to hazardous air pollutants, evaluates the toxicity of a substance, and characterizes the risk to the public. The second, more holistic, view explores how EPA can improve in several critical areas of risk assessment by focusing on cross-cutting themes and incorporating more scientific judgment. This comprehensive volume will be important to the EPA and other agencies, risk managers, environmental advocates, scientists, faculty, students, and concerned individuals.

Abstract  RAGS Part A is one of a three-part series: Part B addresses the development of risk-based preliminary remediation goals; and Part C addresses human health risk evaluations of remedial alternatives. RAGS Part A: Human Health Evaluation Manual provides guidance on the human health evaluation activities that are conducted during the baseline risk assessment - the first step of the Remedial Investigation/Feasibilty Study (RI/FS). The baseline risk assessment is an analysis of the potential adverse health effects (current or future) caused by hazardous substance releases from a site in the absence of any actions to control or mitigate these releases (i.e., under an assumption of no action). The baseline risk assessment contributes to the site characterization and subsequent development, evaluation, and selection of appropriate response alternatives. The results of the baseline risk assessment are used to help determine whether additional response action is necessary at the site, modify preliminary remediation goals, help support selection of the "no- action" remedial alternative, where appropriate, and document the magnitude of risk at a site, and the primary causes of that risk. Baseline risk assessments are site-specific and therefore may vary in both detail and the extent to which qualitative and quantitative analyses are used, depending on the complexity and particular circumstances of the site, as well as the availability of applicable or relevant and appropriate requirements (ARARs) and other criteria, advisories, and guidance. After an initial planning stage, there are four steps in the baseline risk assessment process: data collection and analysis; exposure assessment; toxicity assessment; and risk characterization. The potential users of Part A are the individuals actually conducting health risk assessments for sites, who frequently are contractors to the EPA, other federal agencies, states, or potentientially responsible parties. It is also targeted to EPA staff, including those responsible for review and oversight of risk assessments (e.g. technical staff in the regions) and those responsible for ensuring adequate evaluations of human health risks (i.e., RPMs).

Abstract  This document provides technical support concerning cancer and noncancer risk assessment methods used in the Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health (2000) (USEPA, 2000a; hereafter the 2000 Human Health Methodology). Ambient water quality criteria (AWQC) developed under Section 304(a) of the Clean Water Act (hereafter the CWA or the Act) are based solely on data and scientific judgments on the relationship between pollutant concentrations and environmental and human health effects. The 304(a) criteria do not reflect consideration of economic impacts or the technological feasibility of meeting the chemical concentrations in ambient water. As discussed below, 304(a) criteria are used by States and authorized Tribes to establish water quality standards, and ultimately provide a basis for controlling discharges or releases of pollutants.

Abstract  We investigated activity patterns of 17 elementary school students aged 10-12, and 19 high school students aged 13-17, in suburban Los Angeles during the oxidant pollution season. Individuals' relationships between ventilation rate (VR) and heart rate (HR) were "calibrated" in supervised outdoor walking/jogging. Log VR was consistently proportional to HR; although "calibrations" were limited by a restricted range of exercise, and possibly by artifact due to mouthpiece breathing, which may cause overestimation of VR at rest. Each subject then recorded activities in diaries, and recorded HR once per minute by wearing Heart Watches, over 3 days (Saturday-Monday). For each activity the subject estimated a breathing rate--slow (like slow walking), medium (like fast walking), or fast (like running). VR ranges for each breathing rate and activity type were estimated from HR recordings. High-school students' diaries showed their aggregate distribution of waking hours as 68% slow inside, 8% slow outside, 10% medium inside, 9% medium outside, 1.5% fast inside, 1.5% fast outside. Elementary students' distribution was 47% slow inside, 15% slow outside, 20% medium inside, 12% medium outside, 2.5% fast inside, 3.5% fast outside. Sleep occupied 38% of high-school students' and 40% of elementary students' time; HR were generally lower in sleep than in slow waking activity. High school students' mean VR estimates were 13 L/min for slow breathing, 18 for medium, and 23 for fast; elementary students' were 14 slow, 18 medium, and 19 fast. VR distributions were approximately lognormal. Maximum estimated VR were approximately 70 L/min in elementary and approximately 100 L/min in high school students. Compared to adults studied similarly, students reported more medium or fast breathing, and had equal or higher VR estimates during slow and medium breathing despite their smaller size. These results suggest that, relative to body size, young people inhale larger doses of outdoor air pollutants than adults.

Abstract  In recent years, many cases of soil pollution have been unearthed in the Netherlands. The ingestion of soil particles due to mouthing behaviour of young children is an important potential pathway of exposure and may constitute a health risk. For an assessment of these health risks, a reliable estimation of the daily inadvertent ingestion of soil particles is necessary. A method to estimate soil ingestion is the use of titanium (Ti), aluminium (Al) and acid insoluble residue (AIR) content of the soil as a tracer. By measuring these tracers in faeces of children and in soil, an estimate can be made of the amount of soil ingested. This method can be used if the following conditions are met: tracer intake by other routes (food) is low and not too variable; tracer absorption from soil in the gastro-intestinal (GI) tract is negligible; tracer concentrations in soil are high and not too variable. A small pilot study was conducted among 18 children visiting a nursery school and 6 hospitalized children without any possibility of soil contact. The results of the pilot study indicate that each tracer is present in faeces in highly variable amounts, but that a combination of these three tracers produces a useful picture of potential soil ingestion. Quantitatively, a difference between the two populations of 55 mg/d, expressed as soil ingestion, was found. Despite the small numbers involved, this difference was statistically significant as the population standard deviations were small. In a number of different soil types, tracer concentrations were found to be almost equal. Further studies are planned to test the validity of the assumptions, and to investigate larger child populations living in different circumstances.

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  This paper presents an approach for characterizing the probability of adverse effects occurring in a population exposed to dose rates in excess of the Reference Dose (RfD). The approach uses a linear threshold (hockey stick) model of response and is based on the current system of uncertainty factors used in setting RfDs. The approach requires generally available toxicological estimates such as No-Observed-Adverse-Effect Levels (NOAELs) or Benchmark Doses and doses at which adverse effects are observed in 50% of the test animals (ED50s). In this approach, Monte Carlo analysis is used to characterize the uncertainty in the dose response slope based on the range and magnitude of the key sources of uncertainty in setting protective doses. The method does not require information on the shape of the dose response curve for specific chemicals, but is amenable to the inclusion of such data. The approach is applied to four compounds to produce estimates of response rates for dose rates greater than the RfD.

Abstract  Several authors have considered the importance of exposure timing and how this affects the outcomes observed, but no one has systematically compiled preconceptional, prenatal, and postnatal developmental exposures and subsequent outcomes. Efforts were undertaken to examine the information available and to evaluate implications for risk assessment for several areas: a) respiratory and immune systems, b) reproductive system, c) nervous system, d) cardiovascular system, endocrine system, and general growth, and e) cancer. Major conclusions from a workshop on "Critical Windows of Exposure for Children's Health" included a) broad windows of sensitivity can be identified for many systems but detailed information is limited; b) cross-species comparisons of dose to target tissue and better data on the exposure-dose-outcome continuum are needed; c) increased interaction among scientific disciplines can further understanding by using laboratory animal results in designing epidemiological studies and human data to suggest specific laboratory studies on mechanisms and agent-target interactions; and d) thus far, only limited attention has been given to peripubertal/adolescent exposures, adult consequences of developmental exposures, and genome-environment interactions. More specific information on developmental windows will improve risk assessment by identifying the most sensitive window(s) for evaluation of dose-response relationships and exposure, evaluation of biological plausibility of research findings in humans, and comparison of data across species. In public health and risk management, information on critical windows may help identify especially susceptible subgroups for specific interventions. Key words: children's health, developmental disorders, developmental toxicity, environmental health, risk assessment, teratogen, windows of vulnerability.

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  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 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  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  This report presents detailed information on age- and gender-related differences in the anatomical and physiological characteristics of reference individuals. These reference values provide needed input to prospective dosimetry calculations for radiation protection purposes for both workers and members of the general public. The purpose of this report is to consolidate and unify in one publication, important new information on reference anatomical and physiological values that has become available since Publication 23 was published by the ICRP in 1975. There are two aspects of this work. The first is to revise and extend the information in Publication 23 as appropriate. The second is to provide additional information on individual variation among grossly normal individuals resulting from differences in age, gender, race, or other factors. This publication collects, unifies, and expands the updated ICRP reference values for the purpose of providing a comprehensive and consistent set of age- and gender-specific reference values for anatomical and physiological features of the human body pertinent to radiation dosimetry. The reference values given in this report are based on: (a) anatomical and physiological information not published before by the ICRP; (b) recent ICRP publications containing reference value information; and (c) information in Publication 23 that is still considered valid and appropriate for radiation-protection purposes. Moving from the past emphasis on 'Reference Man', the new report presents a series of reference values for both male and female subjects of six different ages: newborn, 1 year, 5 years, 10 years, 15 years, and adult. In selecting reference values, the Commission has used data on Western Europeans and North Americans because these populations have been well studied with respect to antomy, body composition, and physiology. When appropriate, comparisons are made between the chosen reference values and data from several Asian populations. The first section of the report provides summary tables of all the anatomical and physiological parameters given as reference values in this publication. These results give a comprehensive view of reference values for an individual as influenced by age and gender. The second section describes characteristics of dosimetric importance for the embryo and fetus. Information is provided on the development of the total body and the timing of appearance and development of the various organ systems. Reference values are provided on the mass of the total body and selected organs and tissues, as well as a number of physiological parameters. The third section deals with reference values of important anatomical and physiological characteristics of reference individuals from birth to adulthood. This section begins with details on the growth and composition of the total body in males and females. It then describes and quantifies anatomical and physiological characteristics of various organ systems and changes in these characteristics during growth, maturity, and pregnancy. Reference values are specified for characteristics of dosimetric importance. The final section gives a brief summary of the elemental composition of individuals. Focusing on the elements of dosimetric importance, information is presented on the body content of 13 elements: calcium, carbon, chloride, hydrogen, iodine, iron, magnesium, nitrogen, oxygen, potassium, sodium, sulphur, and phosphorus.

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.

Abstract  This paper represents the first quantitative attempt to distinguish the amount of outdoor soil ingestion from indoor dust ingestion in a soil pica child. Based on a methodology using a comparison of differential element ratios it is estimated that the predominant proportion of the fecal tracers were from outdoor soil and not indoor dust origin. The methodology employed can be utilized on a broader scale to assess the relative amounts of soil and dust consumed by individuals.

Abstract  Assessments of doses resulting from exposures to airborne gases and particles are based almost exclusively on inhalation rates that are inconsistent with the quantities of oxygen needed to metabolize dietary intakes of fats, carbohydrates, and protein. This inconsistency leads to erroneous estimates of inhalation exposures and can distort the relative importance of inhalation and ingestion-based exposures to environmental contaminants that are present in foods, air, and water. As a means of dealing with this problem, a new methodology for estimating breathing rates is presented that is based on the oxygen uptake associated with energy expenditures and a ventilatory equivalent that relates minute volume to oxygen uptake. Three alternative energy-based approaches for estimating daily inhalation rates are examined: (1) average daily intakes of food energy from dietary surveys, adjusted for under reporting of foods; (2) average daily energy expenditure calculated from ratios of total daily expenditure to basal metabolism; and (3) daily energy expenditures determined from a time-activity survey. Under the first two approaches, inhalation rates for adult females in different age cohorts ranged from 9.7 to 11 m3 d-1, whereas for adult males the range was 13 to 17 m3 d-1. Inhalation rates for adults determined from activity patterns were higher (i.e., 13 to 18 m3 d-1), however, those rates were shown to be quite sensitive to the energy expenditures used to represent light and sedentary activities. In contrast to the above estimates, the ICRP 23 reference values for adult females and males are 21 and 23 m3 d-1 (Snyder et al. 1975). Finally, the paper provides a technique for determining the short-term breathing rates of individuals based on their basal metabolic rate and level of physical activity.