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Exposure Index (exposure + index)
Selected AbstractsRelative Exposure Index: an important factor in sea turtle nesting distributionAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 2 2010J. Santana Garcon Abstract 1.The threatened status of many sea turtle populations and their vulnerability to coastal development and predicted climate change emphasize the importance of understanding the role of environmental factors in their distribution and ecological processes. The factors driving the distribution of sea turtle nesting sites at a broad spatial scale is poorly understood. 2.In light of the lack of understanding about physical factors that drive the distribution of turtle nesting, the relationship between nesting site distribution and the exposure of coastal areas to wind and wind-generated waves was analysed. To achieve this, a Relative Exposure Index (REI) was developed for an extensive area in north-eastern Australia and values of the index for nesting sites of five different sea turtle species and randomly selected non-nesting sites were compared. 3.Although there are differences between species, the results show that sea turtles nest in areas of higher REI values suggesting that wind exposure is related to the spatial distribution of sea turtle nesting sites, and it may also influence nest site selection in female turtles and/or the dispersal of hatchlings towards oceanic currents. 4.The combination of these results with further research on other driving environmental factors, like oceanic currents, has the potential to allow for the identification and prediction of future nesting sites, for which conservation and management may become essential. Copyright © 2009 John Wiley & Sons, Ltd. [source] Effects of maternal occupational exposure to organic solvents on offspring visual functioning: A prospective controlled studyBIRTH DEFECTS RESEARCH, Issue 3 2001Christine Till Background Previous studies in adults and animals with high level exposure to organic solvents suggested impairments in visual functioning. The objective of this pilot study was to examine the effects of maternal occupational exposure to organic solvents during pregnancy on offspring color vision and visual acuity, the development of which may be especially vulnerable to organic solvent exposure. Methods We conducted a prospective cohort study of 32 offspring of women who were exposed occupationally to organic solvents during pregnancy compared with 27 nonexposed children. Monocular and binocular color vision and visual acuity were assessed using the Minimalist Test and the Cardiff Cards, respectively. Children with known hereditary color vision loss were excluded. Results Solvent-exposed children had significantly higher error scores on red-green and blue-yellow color discrimination, as well as poorer visual acuity compared with the control group. Exposure index (an estimated measure of exposure intensity) was not significantly related to color discrimination or visual acuity score. Despite excluding all children with a known family history of color vision loss, clinical red-green color vision loss was found among 3 of the 32 exposed children compared with none of the matched controls. Conclusions These preliminary findings suggest that occupational exposure to organic solvents during pregnancy is associated with an increased risk of color vision and visual acuity impairment in offspring. The importance of routine visual function screening in risk assessment after prenatal exposure to chemicals warrants further attention. Teratology 64:134,141, 2001. © 2001 Wiley-Liss, Inc. [source] The Relationship Between Item Exposure and Test Overlap in Computerized Adaptive TestingJOURNAL OF EDUCATIONAL MEASUREMENT, Issue 2 2003Shu-Ying Chen The purpose of this article is to present an analytical derivation for the mathematical form of an average between-test overlap index as a function of the item exposure index, for fixed-length computerized adaptive tests (CATs). This algebraic relationship is used to investigate the simultaneous control of item exposure at both the item and test levels. The results indicate that, in fixed-length CATs, control of the average between-test overlap is achieved via the mean and variance of the item exposure rates of the items that constitute the CAT item pool. The mean of the item exposure rates is easily manipulated. Control over the variance of the item exposure rates can be achieved via the maximum item exposure rate (rmax). Therefore, item exposure control methods which implement a specification of rmax (e.g., Sympson & Hetter, 1985) provide the most direct control at both the item and test levels. [source] Biomarkers of Mn exposure in humansAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 11 2007Donald Smith PhD Abstract Background Studies have reported associations between manganese (Mn) exposures and Mn levels in blood and urine, though the suitability of these biological measures as biomarkers of exposure is not well known. Methods We evaluated whether whole blood, plasma, and urine Mn levels reflect exposures in occupationally exposed humans. Results In active ferroalloy workers, blood Mn was associated with total air Mn levels in subjects currently exposed to low (median,=,0.42 ,g/m3, P,=,0.009) and moderate (median,=,4.2 ,g/m3, P,=,0.007) air Mn levels, but not in workers exposed to the highest Mn levels (median,=,292 ,g/m3, P,=,0.31). In bridge welders blood Mn (P,<,0.01), but not plasma or urine Mn was significantly associated with their cumulative respiratory exposure index. In welders, ,6% (range ,3,9%) of whole blood Mn was contained in the plasma fraction, though there was no association between whole blood and plasma Mn levels (Pearson's R,=,0.258, P,=,0.12). In contrast, in fresh whole blood samples spiked with Mn ex vivo ,80% or more of added Mn partitioned in the plasma, while only ,20% or less partitioned in the cellular fraction. Conclusions These data suggest a complex and limited relationship between exposure and blood Mn levels that may depend upon exposure attributes and the latency of blood sampling relative to exposure; plasma and urine Mn appear to be of little utility as exposure biomarkers. This underscores the need to fully characterize and validate these or other biomarkers for use in constructing appropriate exposure metrics and determining exposure,effect relationships. Am. J. Ind. Med. 50:801,811, 2007. © 2007 Wiley-Liss, Inc. [source] Continued exposure to silica after diagnosis of silicosis in Brazilian gold miners,AMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 10 2006Ana Paula Scalia Carneiro PhD Abstract Background There is a paucity of studies analyzing the effect of continued silica exposure after the onset of silicosis with regard to disease progression. The present study investigates differences in clinical and radiological presentation of silicosis among former workers with a diagnosis of silicosis, and compares workers who continued to be exposed to silica with those who stopped silica exposure after having received their diagnosis. Methods A sample of 83 former gold miners with a median of 21 years from the first diagnoses of silicosis, had their clinical and occupational histories taken and underwent both chest radiography (International Labor Organization standards) and spirometry. Their silica exposure was assessed and an exposure index was created. The main outcome was the radiological severity of silicosis and tuberculosis (TB). The statistical analysis was done by multiple logistic regression. Results Among the 83 miners, 44 had continued exposed to silica after being diagnosed with silicosis. Continuation of silica exposure was associated with advanced radiological images of silicosis (X-ray classification in category 3, OR,=,6.42, 95% CI,=,1.20,34.27), presence of coalescence and/or large opacities (OR,=,3.85, CI,=,1.07,13.93), and TB (OR,=,4.61, 95% CI,=,1.14,18.71). Conclusions Differential survival is unlikely to explain observed differences in silicosis progression. Results reinforce the recommendation that silica exposure should be halted at an early stage whenever X-ray is suggestive of the disease. Am. J. Ind. Med. 49:811,818, 2006. © 2006 Wiley-Liss, Inc. [source] Northern Environment Predisposes Birches to Ozone DamagePLANT BIOLOGY, Issue 2 2007E. Oksanen Abstract: Ozone sensitivity of silver birch (Betula pendula Roth) has been thoroughly investigated since early 1990,s in Finland. In our long-term open-field experiments the annual percentage reduction in basal diameter and stem volume increment were the best non-destructive growth indicators for ozone impact when plotted against AOTX. Remarkable differences in defence strategies, stomatal conductance, and defence compounds (phenolics), clearly indicate that external exposure indices are ineffective for accurate risk assessment for birch. For flux-based approaches, site-specific values for gmax and gdark are necessary, and determinants for detoxification capacity, ageing of leaves, and cumulative ozone impact would be needed for further model development. Increasing CO2 seems to counteract negative ozone responses in birch, whereas exposure to springtime frost may seriously exacerbate ozone damage in northern conditions. Therefore, we need to proceed towards incorporating the most important climate change factors in any attempts for ozone risk assessment. [source] Determination of organic acids in urine by solid-phase microextraction and gas chromatography,ion trap tandem mass spectrometry previous ,in sample' derivatization with trimethyloxonium tetrafluoroborateBIOMEDICAL CHROMATOGRAPHY, Issue 10 2008Marco Pacenti Abstract A method for the determination of the organic acids directly in the urine employing derivatization with trimethyloxonium tetrafluoroborate as a methylating agent and sequential extraction by head space and direct immersion/solid phase microextraction is reported. Furoic acid, hippuric acid, methylhippuric acid, mandelic acid, phenylglyoxylic acid and trans, trans muconic acid contained in urine and proposed by the American Conference of Governmental Industrial Hygienists as biological exposure indices were determined after a fast and economically convenient preparation step and sensitive gas chromatography,ion trap,mass spectrometry/tandem mass spectrometry analysis. Urine is rather a complex sample and hence the acquisition method required specific GC-MS instrumentation capable of supporting the changeover, fully automated during a single chromatographic separation, from mass to tandem mass spectrometry and both chemical and electron ionization modes. The automation of the analytical method provides a number of advantages, including reduced analysis time for both routine analysis and method development, and greater reproducibility. The equilibrium and kinetics of this substances vs head space/direct immersion-solid phase microextraction were investigated and evaluated theoretically. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||