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 role of children's activities in leading to pesticide exposure was evaluated by comparing pesticide loadings on the hands of children with the activities of the same children observed over a 4-h period. In all, 10 children ranging in age from 24 to 55 months were videotaped on the second day following a routine professional crack and crevice chlorpyrifos application in their homes. Before and following the video session, the children's hands were rinsed in isopropyl alcohol. Thus, only the chlorpyrifos that accumulated on and remained on the child's hands during the videotaping were removed for analysis after the videotaping session. The rinsate was analyzed for chlorpyrifos. The children's behaviors were quantified using virtual tracking device and the frequency and duration of behaviors, the hourly rate of behaviors, and the locations in which behaviors occurred were compared to hand loadings of pesticides. Pesticide hand loadings obtained following the videotaping sessions were associated with pesticide levels on surfaces and toys, but not with air levels. Pesticide loadings obtained following the videotaping sessions were also associated with frequencies, durations, and hourly rates of contact with bottles, and object-to-mouth behaviors, as well as contact duration with upholstered/textured surfaces. The hand loadings were also associated with the number of locations where the children exhibited object-to-mouth behavior and with children's use of house space during the videotaping sessions.

Abstract  Pica for lead-containing paint has been questioned as the principal mechanism for the widespread moderately elevated blood lead levels (30 to 80 µg/l00 ml) in inner city children. This study explored the hypothesis that lead-contaminated household dust is a major source of lead for these children; hand contamination and repetitive mouthing is the proposed mechanism of ingestion. Forty-nine inner city children with blood lead 40 to 70 µg/100 ml were matched with 50 children with blood lead ≤29 µg/100 ml from the same inner city environment. House dust lead and lead on hands were found in significantly greater quantity among experimental subjects. Other factors differed between groups; lead content of peeling paint, soil lead, and pica affected more experimental than control children, but did not account for more than 50% of experimental cases. The cause of moderate blood lead elevation is multifactoral: no single source accounted for all children with elevated levels. However, lead contamination of house dust and hands appears to be a major factor in this condition.

Abstract  The National Human Exposure Assessment Survey (NHEXAS)/Minnesota Children's Pesticide Exposure Study (MNCPES) was a population-based study designed to characterize children's exposure to residential pesticides and to evaluate the contribution of residential and children's activities to children's exposure. Families of 168 children were surveyed for residential use of pesticides and children's activities. From these homes, families of 102 children between the ages of 3 and 13 years participated in a week-long intensive exposure study. Of the 102 children, 19 children were videotaped for four consecutive hours in their normal daily activities. The survey responses indicated that the youngest children were more likely to exhibit behaviors that would foster exposure to environmental contaminants. Comparison of questionnaire responses indicated that the videotaped subsample was representative of the exposure study population. The microactivities of the videotaped children that might contribute to their exposure via ingestion or dermal routes were quantified. Hand-to-mouth and object-to-mouth activities were observed most frequently among the youngest children. The youngest children were also most likely to be barefoot both indoors and outside. Gender differences were found in mouthing behavior and the proportion of observed time spent outdoors.

Abstract  A computer-controlled mechanical chamber was used to control the contact between carpet and aluminum sheet samples laden with soil, and human cadaver skin and cotton sheet samples for the measurement of mass soil transfer. The contact parameters of pressure (10-50 kPa) and time (10-50 s) were varied for 768 experiments of mass soil transfer, where two soil types (play sand and lawn soil) and two soil particle sizes (< 139.7 and >= 139.7 <381 mu m) were used. Mean soil mass transfer to cadaver skin was higher than mean transfer to cotton sheets for both carpet and aluminum transfers, and also generally higher pressure was associated with larger amounts of soil transfer for all contact scenarios. The mean soil adherence from carpet was 0.37 +/- 0.4 mg/cm(2), while the mean soil adherence from aluminum was 0.42 +/- 0.6 mg/cm(2). For aluminum, smaller soil particle size was associated with more transfer (p = 0.0349), while for carpet, larger soil size was associated with more transfer (p < 0.0001). Soil type was significant but only for aluminum surface, where sand was associated with higher adherence (p < 0.0001). This data set can be used to improve estimates of dermal exposure to contaminants found in soils and dust present in indoor environments. (C) 2009 Elsevier Inc. All rights reserved.

Abstract  Childrens' touching and mouthing behaviors during outdoor play in urban residential yards were measured using video observations. Descriptions were made of childrens' outdoor residential play environments. Behaviors assessed were used to examine (1) validity of parental responses to questions on childrens' oral behaviors and outdoor play and (2) relationships of mouthing behaviors to blood lead levels (BLLs). Thirty-seven children aged 1-5 years were recruited for 2 h of video recording in their yard and blood lead measurement. Video assessments included hourly rates of hand touches to ground/ walking-level surfaces (cement/stone/steel, porch floor/steps, grass, and bare soil) and oral behaviors. Parental questionnaires assessed their child's outdoor activities, behaviors, and home environment. The children were: mean 39 months; 51% male; 89% Hispanic; and 78% Medicaid or uninsured. Twenty-two children had a blood lead measured (mean 6 m mu/dl). During taping, all children had access to cement, 92% to grass, 73% to bare soil, and 59% to an open porch. Children had frequent touching and mouthing behaviors observed (median touches/h: touches to surfaces 81; hand-to-mouth area (with and without food) 26; hand-in-mouth 7; and object-in-mouth 17). Blood lead was directly correlated with log-transformed rates of hand-in-mouth (Pearson's correlation, r = 0.564, n = 22, P = 0.006) and object-in-mouth (Pearson's correlation, r = 0.482, n = 22, P = 0.023) behaviors. Parental questionnaire responses did not accurately reflect childrens' observed oral behaviors, play habits, or play environment. These data confirm the direct relationship between hand-to-mouth activities and BLLs and fail to validate parental perceptions of their child's mouthing behaviors or outdoor play environment.

Abstract  Measurements of the quantity of lead on the hands of schoolchildren and of the concentration of lead in dust from school playgrounds have been carried out; the hand-lead was collected by wiping with a moist tissue. When hand-lead and dust-lead values were averaged for each school, a statistically significant relationship between the two sets of means was obtained. Some limited measurements of size distribution of the dust particles on the children's wipes were also made; these indicated that most of the particles were less than 10μm in diameter.

Abstract  Yearly from 1974 to 1978, a medical survey was carried out among 11-year-old children attending schools situated less than 1 and 2.5 km from a lead smelter. Age-matched control children from a rural and urban area were examined at the same time. The blood lead levels (PbB) of the children living in the smelter area (mainly those attending schools located less than 1 km from the smelter) were higher than those of rural and urban children. The mean PbB levels were usually lower in girls than in boys, especially in the smelter area. Despite a slightly decreasing trend in the annual mean airborne lead concentration at less than 1 km (mean PbA: from 3.8 μg/m3 in 1974 to 2.3 μg/m3 in 1978) the PbB levels there did not improve, whereas 2.5 km from the plant a significant tendency to normalization of PbB became apparent. Therefore, in the third survey, the medical examination was combined with an environmental study which demonstrated that lead in school-playground dust and in air strongly correlated. Lead on the children's hands (PbH) was also significantly related to lead in air or lead in dust. Less than 1 km from the factory boys and girls had on the average 436 and 244 μg Pb/hand, respectively, vs 17.0 and 11.4 μg Pb/hand for rural boys and girls, respectively. Partial correlations between PbB, PbA, and PbH indicated that in the smelter area the quantitative contribution of PbA to the children's PbB is negligible compared to that of PbH. Thus, the control of airborne lead around the lead smelter is not sufficient to prevent excessive exposure of children to environmental lead. In view of the importance of lead transfer from dust and dirt via hands to the gastrointestinal tract remedial actions should be directed simultaneously against the atmospheric emission of lead by the smelter and against the lead particulates deposited on soil, dust, and dirt.

Abstract  Microlevel activity time series (MLATS) data were gathered on hand contact activities of 38 children (1-6 years old) by videotaping in primarily outdoor residential environments. The videotape recordings were then translated into text files using a specialized software called VirtualTimingDevicetrade mark. Contact frequency (contacts/h), duration per contact (s/contact), and hourly contact duration (min/h) were summarized for outdoor hand contacts with 15 distinct object/surface categories ("Animal", "Body", "Clothes/Towels", "Fabric", "Floor", "Food", "Footwear", "Metal", "Non-dietary Water", "Paper/Wrapper", "Plastic", "Rock/Brick", "Toys", "Vegetation/Grass", and "Wood") and two aggregate object/surface categories ("Non-dietary objects/surfaces" and "Total objects/surfaces"). For outdoor both hand contacts with "Total objects/surfaces", contact frequencies ranged from 229.9 to 1517.7 contacts/h, median durations/contact ranged from < 1 to 5 s, and hourly contact durations ranged from 42.6 to 102.2 m/h. The data were analyzed for significant differences in hand contact activities as a function of (1) age, (2) location, (3) gender, and (4) hand. Significant differences (P < or = 0.05) were found for all four factors analyzed. Hourly contact durations with "Non-dietary objects/surfaces" and "Total objects/surfaces" increased with age (P = 0.01, rs = 0.42 and P = 0.005, rs = 0.46, respectively), while contact frequencies and hourly contact durations with "Wood" decreased with age (P = 0.02, rs = -0.38 and P = 0.05, rs = -0.32, respectively). Location was found to affect contact frequencies and hourly contact durations with certain objects/surfaces. For example, contact frequencies and hourly contact durations with "Fabric" were higher indoors (P = 0.02 for both), while contact frequencies and hourly contact durations with "Vegetation/Grass" were higher outdoors (P = 0.02 and P = 0.04, respectively). Girls had longer hourly contact durations with "Footwear" (P = 0.02), "Non-dietary objects/surfaces" (P = 0.03), and "Total objects/surfaces" (P = 0.01) than boys. The right hand had longer hourly contact durations with objects that are often manipulated with the hand (e.g., "Toys" (P = 0.0002)), while the left hand had longer hourly contact durations with passively touched objects/surfaces (e.g., "Clothes/Towels" (P = 0.003) and "Floor" (P = 0.04)).

Abstract  To reduce the uncertainty associated with current estimates of children's exposure to pesticides by dermal contact and indirect ingestion, residue transfer data are required. Prior to conducting exhaustive studies, a screening study to identify the important parameters for characterizing these transfers was designed. A fluorescence imaging system was developed (Ivancic et al., in press) to facilitate collection of surface residue transfer data for repeated contacts. Next, parameters that affect residue transfer from surface-to-skin, skin-to-other objects, and skin-to-mouth were evaluated using the imaging system and the fluorescent tracer riboflavin as a surrogate for pesticide residues. Riboflavin was applied as a residue to surfaces of interest. Controlled transfer experiments were conducted by varying contact parameters with each trial. The mass of a tracer transferred was measured and the contact surface area estimated using video imaging techniques. Parameters evaluated included: surface type, surface loading, contact motion, pressure, duration, and skin condition. Transfers both onto, and off of, the hand were measured. To efficiently identify parameter changes resulting in significant effects, the Youden ruggedness test was used to select the combination of parameters varied in each contact trial. In this way, more than one parameter could be varied at a time and the number of trials required was minimized. Results of this study showed that surface loading and skin condition (significant at alpha=0.05) are among the important parameters for characterizing residue transfers of riboflavin. Duration of contact within the time range investigated does not have a significant effect on transfer of this tracer. Results of this study demonstrate the potential for collecting dermal transfer data using the Ivancic et al. fluorescence imaging system and provide preliminary data to reduce uncertainty associated with estimating dermal exposures resulting from contact with residue-contaminated surfaces. These data will also aid in determining what additional residue transfer data should be collected and what type of microactivity data are needed to estimate dermal and indirect ingestion exposure to residues on household surfaces.

Abstract  The adhesion of house dust particles and chemical residues to the hands after contact with a variety of surfaces can yield significant exposures to children. Chemicals present on the surface or absorbed into house dust particles may adhere to the hands and subsequently are available for ingestion or absorption through the skin under normal physiological conditions. Contact of a hand with a surface occurs primarily through a thin layer of sebum and sweat on the skin surface. The study presented here examined the effect of the composition of the sebum and sweat layer on the adhesion of a mixture of pesticides and a herbicide to a hand after contact with a house-dust-laden surface. Collection efficiencies on the hand for atrazine and malathion were correlated with sebum levels on the palm of an individual hand. The increase in sebum values measured in this study caused a 13 percent and 8 percent reduction in collection efficiency, respectively, for atrazine and malathion applied to house-dust-laden surfaces. Diazinon and chlorpyrifos collection efficiencies were correlated with skin hydration levels measured on the palm of the individual's hand. The increased skin hydration measured in this study caused a 7 percent and 5 percent reduction in collection efficiency, respectively, for diazinon and chlorpyrifos.

Abstract  Current methods of estimating absorbed dosage (AD) of chemicals were evaluated to determine residue transfer from a carpet treated with chlorpyrifos (CP) to humans who performed a structured exercise routine. To determine the dislodgeability of residue, a California Department of Food and Agriculture (CDFA) roller was applied to a flat cotton cloth upon a treated carpet. Levels ranged from 0.06 to 0.99 microg CP/cm2. Cotton whole body dosimeters (WBD) were also used to assess residue transfer. The dosimeters retained 1.5 to 38 mg CP/person. Urine biomonitoring (3 days) for 3,5,6-trichloro-2-pyridinol (TCP) of persons who wore only swimsuits revealed a mean AD of 176 microg CP equivalents/person. The results show that the AD depends on the extent of contact transfer and dermal absorption of the residue. Default exposure assessments based upon environmental levels of chemicals and hypothetical transport pathways predict excessive exposure. The cotton WBD retains chemical residues and may be effectively used to predict dermal dose under experimental conditions.

Abstract  A videotaping methodology has been developed for use in quantifying the types and frequencies of children's hand and mouthing activities that could lead to exposure to environmental pollutants via dermal and ingestion pathways. Twenty children in day care, ages 3-6 years and 10 children in residences, ages 2-5 years, were videotaped during their waking hours for 1 day. Parents of each child completed questionnaires for the purpose of evaluating the accuracy of parental reports of hand-to-mouth rates. Videotapes were translated as quantifiable activities by two trained observers whose reporting reliability was checked throughout the investigation. Results determined that reliability of the videotaping method was very good, even over a year post-training. From videotape data, the average hand-to-mouth frequency rate was determined to be 9.5 contacts/h. These values are considerably higher than the current default value of 1.56 contacts/h under consideration by the EPA.

Abstract  Permethrin is an agricultural insecticide of great interest to the military because of its repellency toward disease-bearing insects when impregnated into uniforms. However, migration of the substance from clothing to the skin surface is of toxicological importance. To quantitate leaching from treated clothing, studies were performed in which swatches of fabric impregnated with 14C-labeled permethrin were applied to the backs of rabbits for 1 wk. Permethrin migration was quantitated by measuring the fate of the 14C label. Conditions that could affect leaching and/or absorption were also evaluated, that is, varying environments, the presence of sweat, different fabric types, and the effects of prelaundering. Results showed that fabric treated with permethrin at a rate of 0.125 mg/cm2 lost the substance to the skin surface at an average rate of 0.49%/d. At the end of the 7-d exposures in rabbits, about 3.2% of the available permethrin had reached the skin, 2% having been recovered from excreta (absorbed) and 1.2% remaining on the skin surface. Prelaundering the treated fabric had little effect on migration rate, nor did the other variables tested. Exposure dose to humans from wearing permethrin-treated (0.125 mg/cm2) military clothing is predicted to be 6 x 10(-4) mg/kg/d.

Abstract  For the U.S. population in the age range 18 to 74 years, we estimated distributions for total body surface area for men and women using Monte Carlo simulations based on estimated bivariate distributions for height and weight. Surface area is well fit by individual lognormal distributions for men and women. These distributions are appropriate for use in public health risk assessments. We also examined the effect of the correlation between height and weight on the surface area distributions.

Abstract  A series of laboratory, greenhouse, and field experiments have been conducted at the University of Washington to improve the empirical grounding of dermal/soil pathway risk calculations. This article presents results from controlled trials, conducted in a greenhouse, in which volunteers engaged in activities in soil amended with a fluorescent marker. Activities included transplanting of bedding plants and laying of pipe by adults and children's play. Soil contact on hands, forearms, lower legs, and faces was examined using both fluoro-metric and gravimetric measurements. Results provide information on pre- and postactivity loadings, the extent of contact associated with the selected activities, and the effects of clothing, activity duration, and soil moisture. Preactivity loadings were consistent with previously reported observations. Following activity, skin coverage was found to be substantially incomplete except on hands. Local soil loadings may therefore deviate markedly from mean values obtained by washing skin surfaces. A protective effect of clothing was observed but may reflect the relatively short duration of the experiments and the use of freshly laundered clothing. No significant trend in soil loading with exposure duration was found, although some evidence of increasing surface area involvement with time was observed. Finally, wet soil activities produced consistently higher loadings on volunteers' hands than dry soil activities.

Abstract  OBJECTIVE: To compare length and stature measurements of young children and to examine the relevance of any difference for comparison with body mass index (BMI) references designed for use from birth to adulthood.

SUBJECTS: A total of 426 2-y-old and 525 3-y-old children included in the Dortmund Nutritional and Anthropometrical Longitudinally Designed (DONALD) Study.

DATA ANALYSIS: Length and stature were measured to the nearest millimetre using a stadiometre. Agreement between both measurements at age 2 and 3 y, respectively, was determined by mean differences and by comparison with the German BMI reference.

RESULTS: The average length of 2-y-old girls and boys was 88.3 (3.1) and 89.9 (3.2) cm, mean differences (stature minus length) were -0.47 (0.65) and -0.45 (0.64) cm. The corresponding BMI values were 16.18 (1.3) and 16.46 (1.2) kg/m2, with mean differences of +0.17 (0.24) and +0.16 (0.23). According to stature, 9.4% of the girls and 10.8% of the boys were overweight (>90th percentile), while length classified 7.1 and 9.4% as overweight. Similar mean differences between length and stature were observed at age 3 y: -0.53 (0.62) and -0.47 (0.65) cm in height and +0.17 (0.20) and +0.14 (0.20) kg/m2 in the BMI of girls and boys, respectively. According to stature, 7.6 and 7.3% were overweight as opposed to 5.4 and 4.8% using length. The observed differences increased with higher BMI levels.

CONCLUSION: Changing measurements from length to stature results in an upward shift of BMI, not reflected in current European BMI references. This small but systematic error may result in misinterpretation of individual BMI levels or trend observations.

Abstract  This study was conducted to describe exposure prone behaviors of infants and toddlers in the farmworker community. Analysis of hand and mouth contact frequencies and durations aids understanding of how children interact with their environment and are exposed via contact with surfaces. All 23 participating children (8 female infants, 5 male infants, 5 female toddlers and 5 male toddlers) lived with at least one farmworker. Children were videotaped at home for 2-6 h. Video footage was translated into micro-level activity time series (MLATS) for both hands and the mouth. MLATS were processed to calculate hourly duration in microenvironments, contact frequency, hourly contact duration and median contact duration. The median hourly duration spent indoors was 53 min/h. The median hand-to-mouth frequency was 15.2 events/h and the median object-to-mouth frequency was 27.2 events/h. The hourly mouthing duration was 1.2 and 2.2 min/h with the hands and objects, respectively. The median mouthing duration with hands and objects was 2 s. The median contact frequency for both hands combined was 689.4 events/h with an hourly contact duration of 100.5 min/h and a median contact duration of 3s. Infants had higher mouthing frequencies with non-dietary objects while toddlers had higher mouthing frequencies with objects associated with pica (i.e., paper). Boys had higher contact frequencies while girls had longer contact durations. These sub-group differences indicate factors such as age and gender should be accounted for when conducting exposure assessments. Contact frequencies in this study are higher than current US EPA recommendations, questioning their protective value for infants and toddlers.