Pesticide exposure may differentially impact young children; they live closer to the ground and take in greater amounts of food relative to body mass than older children or adults. We are using an organophosphate ( OP ) urinary biomarker screen ( gas chromatography with flame photometric detection, GC / FPD ) to evaluate pesticide exposure among 154 children 6 years of age living in a heavily farmed border ( US ± Mexico ) community. The screen detects diethylphosphates ( DEPs ) and dimethylphosphates ( DMPs ) above a reference range of 1000 non -occupationally exposed individuals ( DL= 25 g / g creatinine, Cr ) . At least one metabolite was detected for 33% of the subjects; many samples contained multiple biomarkers. DEP was detected in 5% of the subjects. DMP and DMTP were frequently measured ( 25% and 26%, respectively ) . Biomarker concentrations are adjusted by the body's metabolism of Cr as an indicator of urine dilution. Cr concentrations were examined separately to evaluate their effect on internal dose measures. Cr concentrations were significantly different by season ( K ± W = 0.83, P= 0.022 ) . Significant differences exist between the autumn:spring ( P= 0.038 ) Cr concentrations and between summer:autumn ( P= 0.041 ) Cr concentrations based on Mann ± Whitney U = 1070.5, z = À 2.041, ( P= 0.041 ) . Our analysis of NHANES III data did not reflect seasonal Cr differences for 6 year olds. No younger children were included. Absorbed daily dose ( ADD ) estimates were calculated for children with the highest concentrations of metabolite. Calculations are theoretical values assuming that the entirety of a given metabolite was metabolized from a single pesticide. Several class -appropriate pesticides were evaluated. For the children with the highest levels, almost all estimated ADDs exceeded the RfD. Although the actual metabolite concentrations dropped appreciably, ADD were still exceeded RfDs at the 95th percentile. The urinary OP screen was effective in identifying subjects with atypical internal doses. Daily Cr yield is a critical component in ADD calculations. Cr variability produces differences in internal dose measurement and estimates of ADD independent of exposure. Cr variability among young children needs to be examined, and caution should be applied when evaluating Cr adjusted internal doses for children. Journal of Exposure Analysis and Environmental Epidemiology ( 2000 ) 10, 672 ± 681.

NHEXAS AZ is a multimedia, multipathway exposure assessment survey designed to evaluate metals and other analytes. This paper reports the analytespecific concentration distributions in each of the media examined (air, soil, house dust, food, beverage, and water), for various methodologies used (inductively coupled plasma-atomic emission spectroscopy and hydride generation-atomic absorption spectroscopy). Results are reported for the five primary metals (Pb, As, Cd, Cr, and Ni). Ingestion was the most important pathway of exposure. Metal concentrations in air were very low (ng / m 3 ) and found only above the 90th percentile. Metals were commonly found in house dust and soil. Exposure transfer coefficients minimize the importance of this component for those over the age of 6 years. When ranked by exposure, food, beverage, and water appeared to be the primary contributors of metal exposure in NHEXAS AZ. For instance, at the 90th percentile, Pb was undetected in air, found at 131 and 118 g / m 3 in floor dust and soil, respectively, and measured at 16 g / kg in food, 7.1 g / kg in beverage, and 2.0 and 1.3 g / l in drinking and tap water, respectively. We calculated preliminary estimates of total exposure (g /day) for each participant and examined them independently by age, gender, and ethnicity as reported by the subjects in the NHEXAS questionnaire. At the 90th percentile for Pb, total exposures were 64 g /day across all subjects (n =176); adult men (n = 55) had the greatest exposure (73 g /day) and children (n =35) the least (37 g /day). Hispanics (n = 54) had greater exposure to Pb (68 g /day) than non-Hispanics (n =119; 50 g /day), whereas non-Hispanics had greater exposure for all other metals reported. These results have implications related to environmental justice. The NHEXAS project provides information to make informed decisions for protecting and promoting appropriate public health policy.

Within the context of the National Human Exposure Assessment Survey (NHEXAS), metals were evaluated in the air, soil, dust, water, food, beverages, and urine of a single respondent. Potential doses were calculated for five metals including arsenic. In this paper, we seek to validate the potential dose calculations through spatial analysis of the data. Others report elevated arsenic concentrations in biological and environmental samples from residents of mining towns, particularly Ajo, Arizona. These reports led us to expect potential arsenic doses above the 90th percentile of the NHEXAS exposure distribution to be from residents of mining communities. Arsenic dose was calculated using media concentrations, time activity patterns, and published exposure factors. Of the 179 homes evaluated, 54 were in mining communities; 11 of these were considered separately for reasons of population bias. Of the 17 homes with the greatest potential arsenic doses, almost half (47%) were in mining communities. We evaluated the potential doses by media from nonmining and mining areas using the nonparametric Mann±Whitney U test. Statistically significant ( p = 0.05) differences were found between mining (n = 43) and nonmining sites (n = 122) for total exposure and for each of the following media: house dust, yard soil, outdoor air, beverage consumed, and water consumed. No differences were found in either food or indoor air of mining and nonmining areas. We eliminated outliers and repeated the test for all media; significance increased. Dietary, organic arsenic from fish consumption contributed to elevated arsenic exposure among people from nonmining communities and acted as an initial confounder. When controlling for fish consumption, we were able to validate our potential dose model using arsenic, particularly in Ajo. Further, we identified three mining communities lacking elevated arsenic exposure. Additional work is needed speciating the arsenic and evaluating health risks. The utilization of Geographic Information System facilitated spatial this project and paves the way for more sophisticated future spatial analyses.

Evaluators must seek methods that convey the results of an evaluation so that those who intend on using the information easily understand them. The purpose of this article is to describe how Geographic Information Systems (GIS) can be used to assist evaluators to convey complex information simply, via a spatial representation. Although the utility of GIS in such disciplines as geography, planning, epidemiology and public health is well documented, a review of the literature suggests that its usefulness as a tool for evaluators has gone relatively unnoticed. The paper posits that evaluators may have not recognized the potential of GIS, because of two beliefs that GIS can only provide cross-sectional, snapshots of data, and hence cannot depict change and that many of the available databases that underlie GIS do not contain data relevant to the evaluation at hand. This article demonstrates how GIS can be used to plot change over time, including impact and outcome data gathered by primary data collection.

Herbivorous insects exhibit strong feeding preferences when choosing among plant genotypes, yet experiments to map loci mediating plant susceptibility to herbivory rarely incorporate host choice. To address this gap, we applied genome-wide association (GWA) mapping to uncover genetic polymorphisms mediating damage from foraging insects (two populations of Scaptomyza flava) across a mixture of Arabidopsis thaliana genotypes in experimental enclosures. The effect of chemical defenses (glucosinolates) on herbivory depended on herbivore genotype. Unlike many studies that minimize the effects of host choice behavior, we also found a large effect of plant size on herbivory-likely through its effect on plant apparency-that was independent of herbivore genotype. These herbivory-associated loci are polymorphic at fine spatial scales, and thus have potential to shape variation in herbivory within natural populations. We also show that the polymorphism with the largest effect on herbivory underlies adaptive latitudinal variation in Arabidopsis plant size across Europe. Overall, our results provide genetic support for ecological observations that variation in both chemical defenses and non-canonical defense traits (e.g., plant size and phenology) jointly shapes plant-herbivore interactions.Interactions between plants and herbivores drive fundamental ecological and evolutionary processes. Herbivores remove 5-20% of the leaf tissue produced annually by plants 1, 2 , which reduces plant fitness 3, 4 , selects against susceptible plant genotypes 4-6 , and in turn shapes the composition of ecological communities through effects that cascade across trophic levels 7 . Understanding the mechanistic bases of plant-herbivore interactions is therefore a major goal in biology and agriculture [8][9][10] .Within plant species, individuals incur different amounts of damage from herbivores, and genetic differences among individuals explain a substantial proportion of this variation (e.g., 11 ). Identifying and characterizing specific genetic polymorphisms that shape herbivoryrelated phenotypes within plant populations, which we refer to as a gene-focused approach, offers a number of advantages for understanding how this variation arises and why it persists [12][13][14][15] . First, in-depth functional studies of genes harboring these variants can uncover specific biochemical and physiological processes that mediate interactions with herbivores 4 . Second, phenotypic comparisons among natural plant accessions or genetically engineered genotypes that vary at genes of interest can reveal how susceptibility to herbivory is linked to or trades off with other traits, including those of interest to evolutionary biologists (e.g., plant reproductive success 16 ) or crop breeders (e.g., plant biomass or yield). Third, population genetic studies, in which patterns at genes of interest are compared with neutral polymorphisms across the genome, can reveal how environmental pressures shape adaptive genetic variation within and among populations at loci a...