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  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  Anthropometry plays an important role in human factors considerations for safe product design, particularly for the 31% of the U.S. population under age 19. This paper discusses two nationwide studies conducted for Consumer Product Safety Commission to obtain center of gravity, linkage, shape and functional body measurement data on 8154 infants, children, and teenagers representative of the U.S. population, for consumer product design, hazard assessment and guidance in establishing requirements or recommendations in standards.

Abstract  Information on the fraction of total hand surface area touching a contaminated object is necessary in accurately estimating contaminant (e.g., pesticides, pathogens) loadings onto the hands during hand-to-object contacts. While several existing physical-stochastic human exposure models require such surface area data to estimate dermal and non-dietary ingestion exposure, there are very limited data sets. This paper provides statistical distributions of fractional surface areas (FSAs) for children's outdoor hand contacts. These distributions were constructed by combining information collected from two distinct studies exploring children's activity patterns and quantifying hand contact surface area. Results show that for outdoor contacts with "All Objects", a range of 0.13-0.27 captured median FSAs, while a range of 0.12-0.24 captured time-weighted FSAs. Overall, an FSA of 0.31 captured 80-100% of FSAs involved in each child's outdoor hand contacts, depending upon the object of interest. These values are much lower than the often conservative assumptions of up to 1 (i.e., the entire hand) that researchers currently make regarding FSAs involved in indoor and outdoor contacts [USEPA, 1997. Standard operating procedures (SOPs) for residential exposure assessments. Contract no. 68-W6-0030. http://www.epa.gov/pesticides/trac/science/trac6a05.pdf].

Abstract  A simple formula was presented for calculating surface area from weight, SA = [image]. It applies to the weight range between 1.5 and 100 kg with no less accuracy than the Du Bois formula, and it is recommended for use not only in prescription of drugs and fluids but also for calculation of the basal metabolic rate and other physiological indices.

Abstract  Estimates of body surface area were made based on measurement of 81 subjects, ranging from premature infants to adults. SA was calculated geometrically for each subject from 34 body measurements, and the values obtained compared with those based on previously published formulas and graphs. The most widely used formula, that of Du Bois and Du Bois, increasingly underestimated SA as values fell below 0.7 m2; the disparity was greatest in the newborn infant (7.96%). Closer agreement was obtained with the equations and nomograms of Body, Brody, Faber and Melcher, and Sendroy and Cecchini, although minor deviations were noted in some age ranges. The formula SA (m2) = weight (kg)0.5378 X height (cm)0.3964 X 0.024265, derived from the measured data by multiple regression analysis, gave a good fit for all values of SA from less than 0.2 m2 to greater than 2.0 m2 (r = 0.998). This formula was used to construct nomograms for estimation of SA in infants, children, and adults from height (length) and weight.

Abstract  Assessments of aggregate exposure to pesticides and other surface contamination in residential environments are often driven by assumptions about dermal contacts. Accurately predicting cumulative doses from realistic skin contact scenarios requires characterization of exposure scenarios, skin surface loading and unloading rates, and contaminant movement through the epidermis. In this article we (1) develop and test a finite-difference model of contaminant transport through the epidermis; (2) develop archetypal exposure scenarios based on behavioral data to estimate characteristic loading and unloading rates; and (3) quantify 24-hour accumulation below the epidermis by applying a Monte Carlo simulation of these archetypal exposure scenarios. The numerical model, called Transient Transport through the epiDERMis (TTDERM), allows us to account for variable exposure times and time between exposures, temporal and spatial variations in skin and compound properties, and uncertainty in model parameters. Using TTDERM we investigate the use of a macro-activity parameter (cumulative contact time) for predicting daily (24-hour) integrated uptake of pesticides during complex exposure scenarios. For characteristic child behaviors and hand loading and unloading rates, we find that a power law represents the relationship between cumulative contact time and cumulative mass transport through the skin. With almost no loss of reliability, this simple relationship can be used in place of the more complex micro-activity simulations that require activity data on one- to five-minute intervals. The methods developed in this study can be used to guide dermal exposure model refinements and exposure measurement study design.

Abstract  Developmental efforts and experimental data that focused on quantifying the transfer of particles on a mass basis from indoor surfaces to human skin are described. Methods that utilized a common fluorescein-tagged Arizona Test Dust (ATD) as a possible surrogate for housedust and a uniform surface dust deposition chamber to permit estimation of particle mass transfer for selected dust size fractions were developed. Particle transfers to both wet and dry skin were quantified for contact events with stainless steel, vinyl, and carpeted surfaces that had been pre-loaded with the tagged test dust. To better understand the representativeness of the test dust, a large housedust sample was collected and analyzed for particle size distribution by mass and several metals (Pb, Mn, Cd, Cr, and Ni). The real housedust sample was found to have multimodal size distributions (mg/g) for particle-phase metals. The fluorescein tagging provided surface coatings of 0.11-0.36 ng fluorescein per gram of dust. The predominant surface location of the fluorescein tag would best represent simulated mass transfers for contaminant species coating the surfaces of the particles. The computer-controlled surface deposition chamber provided acceptably uniform surface coatings with known particle loadings on the contact test panels. Significant findings for the dermal transfer factor data were: (a) only about 1/3 of the projected hand surface typically came in contact with the smooth test surfaces during a press; (b) the fraction of particles transferred to the skin decreased as the surface roughness increased, with carpeting transfer coefficients averaging only 1/10 those of stainless steel; (c) hand dampness significantly increased the particle mass transfer; (d) consecutive presses decreased the particle transfer by a factor of 3 as the skin surface became loaded, requiring approximately 100 presses to reach an equilibrium transfer rate; and (e) an increase in metals concentration with decreasing particle size, with levels at 25 microns typically two or more times higher than those at 100 microns--consistent with the earlier finding of Lewis et al. for the same sample for pesticides and polycyclic aromatic hydrocarbons (PAHs).

Abstract  Dermal contact with contaminated soils may be a significant route of human exposure to toxic substance under some circumstances. Soil adherence to skin is an important determinant of such exposures, but factors influencing soil adherence are generally not well characterized. Petroleum hydrocarbons are often found in contaminated soils at relatively high concentrations. Results of an investigation of the influence of motor oil on soil adherence to skin are reported here. Studies were conducted at three oil concentrations (0, 1, and 10% by weight) under wet and dry conditions in three different soil types. Only two of six soil/moisture combinations showed consistently increasing adherence with increasing oil content. Overall, an increase was found in wet, but not dry soils. The results indicate that high concentrations of petroleum contaminants can increase the dermal adherence of soil, but that the magnitude of the effect is likely to be modest.

Abstract  The transfer of pesticide residues from a carpeted floor to human subjects wearing dosimeter clothing was measured. Subject motions were standardized using aerobic dance routines (JazzerciseR). This method allows reproducible exposure assessment and the derivation of transfer coefficients reflecting transfer of surface residues to exposed subjects.

Abstract  The risk associated with the dermal absorption of chemicals from contaminated soil is, in part, a function of particle size distribution, as determined by either dry or wet sieving techniques. For the soils tested, the adhered soil fractions were shown to be independent of organic matter content and soil origin. Soil moisture content becomes a factor only for very moist soils. Results show that the adhered fractions of dry or moderately moist soils with wide distributions of particle sizes generally consist of particles of diameters <63 microm. Consequently, dermal absorption experiments using larger size fractions may be of limited relevance to actual situations of soil exposure.

Abstract  Contaminated site cleanup decisions may require estimation of dermal exposures to soil. Telephone surveys represent one means of obtaining relevant activity pattern data. The initial Soil Contact Survey (SCS-I), which primarily gathered information on the activities of adults, was conducted in 1996. Data describing adult behaviors have been previously reported. Results from a second Soil Contact Survey (SCS-II), performed in 1998-1999 and focused on children's activity patterns, are reported here. Telephone surveys were used to query a randomly selected sample of U.S. households. A randomly chosen child, under the age of 18 years, was targeted in each responding household having children. Play activities as well as bathing patterns were investigated to quantify total exposure time, defined as activity time plus delay until washing. Of 680 total survey respondents, 500 (73.5%) reported that their child played outdoors on bare dirt or mixed grass and dirt surfaces. Among these "players," the median reported play frequency was 7 days/week in warm weather and 3 days/week in cold weather. Median play duration was 3 h/day in warm weather and 1 h/day in cold weather. Hand washes were reported to occur a median of 4 times per day in both warm and cold weather months. Bath or shower median frequency was seven times per week in both warm and cold weather. Finally, based on clothing choice data gathered in SCS-I, a median of about 37% of total skin surface is estimated to be exposed during young children's warm weather outdoor play.

Abstract  Thirty-three hours of videotape collected in a 1993 pilot study were quantified, via a video translation software application, to obtain left and right hand activity data of four children of farmworkers. Reported here are the children's contact duration and frequency for each object in their environment, duration spent in each location and activity exertion level, and frequency distributions of object contact durations. The pilot study provided valuable information for evaluating and improving videotaping and videotape translation methodologies as a means of gathering activity information that can be used to refine dermal exposure estimates. Although a larger database of children's videotaped activities for different ages and populations is needed before generalizations can be made, the data presented here are the most detailed information to date for children's micro-level dermal activities.

Abstract  The document is intended to support EPA's Exposure Assessment Guidelines by providing data and information on standard factors that are used to calculate human exposure to toxic substances. Statistical distributions or ranges of values were developed for body weight, skin surface area, and ventilation rates. Percentile distributions of body weight were computed from the Second National Health and Nutrition Examination Survey (NHANES II) data base using a computer program that performs variance estimation of multistage sample data using the Jack-knife Repeated Replicate approach. Distributions of skin surface areas were similarly calculated from NHANES height and weight data by applying regression equations that were either located in the literature or were developed by multi-variate analysis of available measurements. Insufficient data precluded the development of distributions of ventilation rates. Minimum, maximum, and mean values of minute ventilation at three activity levels were calculated from available measurements. Activity pattern information is presented to permit the calculation of time-weighted average ventilation rates.

Abstract  A ring of polyurethane foam (PUF ring) on a stainless steel roller (PUF roller) is designed to simulate a young child's dermal exposure as it is pulled over a sampling surface. This is an economical and consistent sampling device which always applies constant weight on the sampling surface. We found there is no statistically significant difference between the recovery of any of 13 pesticide residues from aluminum foil by this sampling device as it rolls over these residues and by dermal pressing on these residues with the human hand heel.

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 individual thickness of the stratum corneum is required to normalise drug permeation profiles in dermato-pharmacokinetic studies. The thickness is often estimated using tape-stripping combined with transepidermal water loss measurements. A linear transformation of Fick's first law is used to relate the progressively thinner barrier with the corresponding increase in transepidermal water loss and to estimate the thickness by linear regression. However, the data from an important subset of subjects are poorly fitted to this linear model. This is typically due to the removal of loose outer layers of stratum corneum, which do not contribute significantly to barrier function. This work proposes two alternative non-linear models. All three models were used to fit data from 31 in vivo tape-stripping experiments and their outcomes and goodness-of-fit compared. The results suggest that the linear model may overestimate the stratum corneum thickness and is open to subjectivity regarding the selection of data points to be fitted. The non-linear models satisfactorily fitted all the data, including all data points. No significant differences were found between the thicknesses derived from the two non-linear models. However, the analysis of the goodness-of-fit of the models to the data suggests a preference for a baseline-corrected approach.

Abstract  Surface area to body weight ratios were calculated for three age groups of the population using direct measurement data reported in the scientific literature. A strong negative correlation was observed between these ratios and age, and ratios did not differ as a function of sex. Distribution data for surface area to body weight ratios are presented for three age groups. Because of the strong correlation between these two factors, the use of these distributions in human exposure/risk assessments using point estimation techniques and/or Monte Carlo simulations may be more appropriate than treating surface area and body weight as independent variables.

Abstract  A simple, rapid, and accurate method of calculating human body surface area from ht. and wt. has been developed. From the empirical relationships of ht. plus wt. (in cm. and kg., respectively), and the "shape" factor of the ratio of wt. to ht., charts have been constructed for the graphical estimation of surface area values in the range from 0.05 to 3.0 m2. From these master charts a diagram has been constructed whereby surface areas may be obtained with the same accuracy and more conveniently, from values of ht. and wt. alone. A comparative evaluation and statistical analysis of the method applied to 252 measurements of surface area has been made. The results indicate a margin of superiority in respect to accuracy, espec. in the case of abnormal body types, for the present graphical method as compared with the well-known Du Bois ht.-wt. formula. The self-adjusting power equation of Boyd has been found to give results generally comparable to those obtained by our diagram. According to these tests, the equation of Breitmann has been found to be biased and not sufficiently accurate to merit consideration for further use. All factors considered, the presently proposed graphical method would seem to be generally superior to other methods of obtaining a value for surface area from the simple physical measurements of ht. and wt. A consideration of the rationale of the anthropometric relationships evolved, indicates that they are in accord with accepted concepts pertaining to the growth and development of the human body.