Abstract  Children are often more heavily exposed to environmental toxicants than adults. They consume more food and water and have higher inhalation rates per pound of body weight than adults. Young children play close to the ground and come into contact with contaminated soil outdoors and with contaminated dust on surfaces and carpets indoors. As another example, exposure to chemicals in breast milk affects infants and young children. Although NCEA has published the Exposure Factors Handbook in 1997 (EPA/600/P-95/002Fa-c), that include exposure factors and related data on both adults and children, the EPA Program Offices identified the need to consolidate all children exposure data into one document. The goal of the Child-Specific Exposure Factors Handbook is to fulfill this need. The document provides a summary of the available and up-to-date statistical data on various factors assessing children exposures. These factors include drinking water consumption, soil ingestion, inhalation rates, dermal factors including skin area and soil adherence factors, consumption of fruits and vegetables, fish, meats, dairy products, homegrown foods, breast milk, activity patterns, body weight, consumer products and life expectancy.

Abstract  The Guidelines for Exposure Assessment describe the general concepts of exposure assessment including definitions and associated units, and by providing guidance on the planning and conducting of an exposure assessment. Guidance is also provided on presenting the results of the exposure assessment and characterizing uncertainty. Although these Guidelines focus on exposures of humans to chemical substances, much of the guidance also pertains to assessing wildlife exposure to chemicals, or human exposures to biological, noise, or radiological agents. The Guidelines include a glossary which helps standardize terminology used by the Agency in exposure assessment. They emphasize that exposure assessments done as part of a risk assessment need to consider the hazard identification and dose-response parts of the risk assessment in the planning stages of the exposure assessment so that these three parts can be smoothly integrated into the risk characterization. The Guidelines discuss and reference a number of approaches and tools for exposure assessment, along with discussion of their appropriate use. The Guidelines also stress that exposure estimates along with supporting information will be fully presented in Agency risk assessment documents, and that Agency scientists will identify the strengths and weaknesses of each assessment by describing uncertainties, assumptions, and limitations, as well as the scientific basis and rationale for each assessment.

Abstract  The National Center for Environmental Assessment Staff (NCEA) have prepared this handbook to provide information on various physiological and behavioral factors commonly used in assessing children’s exposure to environmental chemicals. Children have different exposure circumstances than do adults. Understanding these differences is key for evaluating potential for environmental hazards from pollutants. They consume more of certain foods and water and have higher inhalation rates per unit of body weight than adults. Young children play close to the ground and come into contact with contaminated soil outdoors and with contaminated dust on surfaces and carpets indoors. Ingestion of human milk may be another potential pathway of exposure for infants and young children. Cover of the Child-Specific Exposure Factors HandbookIn 1997, NCEA published the first Exposure Factors Handbook (EPA/600/P-95/002Fa-c), which includes exposure factors and related data on both adults and children. The goal of the Child-Specific Exposure Factors Handbook is to consolidate all child exposure data into one single document. This document would provide a summary of the available and up-to-date statistical data on various factors assessing child exposures. These factors include drinking water consumption, soil ingestion and non-dietary factors, inhalation rates, dermal factors including skin area and soil adherence factors, consumption of fruits and vegetables, fish, meats, dairy products, homegrown foods, human milk, activity patterns, body weight, and consumer products. This report is an update of the 2002 interim final version of this handbook. The 2008 version provides analysis of exposure factors data using EPA's recommended age groups for assessing childhood exposures.

Abstract  Below is a summary of the recommendations reached by the Methodological Subcommittee of the HNIS/NCHS Analytic Working Group on the issues of variance estimation and statistical reporting standards. Specific recommendations are underlined, whereas suggested practices are italicized. The implementation of these recommendations and suggestions will vary from survey to survey and, perhaps, from estimate to estimate. Nevertheless, official agency publications should contain a "statistical notes" section describing the variance estimation and statistical reporting standards used therein. The design-based approach to the estimation and analysis of survey data is assumed here. Unlike model-dependent alternatives, the design-based approach makes few assumptions about the nature of the data being summarized and/or analyzed. Two aspects of the sampling design must be taken into account when using this approach: the sample weights and the complex sample design (stratified, multi-stage sampling). Weights are used in the this approach when estimating mean, medians, and other descriptive statistics as well as analytical statistics like regression coefficients. Both weights and indicators of stratum and primary sampling unit (PSU) membership are used when estimating variances and testing for statistical significance. In general, using statistical weights that reflect the probability of selection and propensity of response for sampled individuals will affect parameter estimates, while incorporating the attributes of the complex sample design (i.e., clustering and stratification) will affect estimated standard errors and thereby test statistics and confidence intervals. The recommendations for presentation of statistical data that follow arise from the issue of sampling variability, and reflect the random way (in the rigorous statistical sense) in which the sample was selected. Although beyond the scope of this report, a consideration of nonsampling issues such as measurement error, nonresponse bias, and other methodological biases are necessary for any thorough interpretation and evaluation of the validity of survey findings.

Abstract  The document provides a summary of the available data on various factors used in assessing human exposure including drinking water consumption, consumption rates of broad classes of food including fruits, vegetables, beef, dairy products, and fish; soil ingestion; inhalation rate; skin area; lifetime; activity patterns; and body weight. Additionally, a number of specific exposure scenarios are identified with recommendations for default values to use when site-specific data are not available. The basic equations using these parameters to calculate exposure levels are also presented for each scenario. Default values are presented as ranges from typical to reasonable worst case and as frequency distributions where appropriate data were available. Finally, procedures for assessing the uncertainties in exposure assessments are also presented with illustrative examples. These procedures include qualitative and quantitative methods such as Monte Carlo and sensitivity analysis.

Abstract  The Exposure Factors Handbook provides a summary of the available statistical data on various factors used in assessing human exposure. This Handbook is addressed to exposure assessors inside the Agency as well as outside, who need to obtain data on standard factors to calculate human exposure to toxic chemicals. These factors include: drinking water consumption, soil ingestion, inhalation rates, dermal factors including skin area and soil adherence factors, consumption of fruits and vegetables, fish, meats, dairy products, homegrown foods, breast milk intake, human activity factors, consumer product use, and residential characteristics. Recommended values are for the general population and also for various segments of the population who may have characteristics different from the general population. NCEA has strived to include full discussions of the issues that assessors should consider in deciding how to use these data and recommendations.

Abstract  This report provides a set of early-life stage age groups for U.S. Environmental Protection Agency (EPA, or the Agency) scientists to consider when assessing children's exposure to environmental contaminants and the resultant potential dose. These recommended age groups are based on current understanding of differences in behavior and physiology that may impact exposures in children. A consistent set of early-life age groups, supported by an underlying scientific rationale, is expected to improve Agency exposure and risk assessments for children by increasing the consistency and comparability of risk assessments across the Agency, improving accuracy and transparency in assessments for those cases where current practice might too broadly combine behaviorally and physiologically disparate age groups, and fostering a consistent approach to future exposure surveys and monitoring efforts to generate improved exposure factors for children.