Rollover injury: effects of near- and far-seating position, belt use, and number of quarter rolls

PURPOSE: Vehicle and occupant responses in rollovers are complex since many factors influence both. This study analyzes the following factors: 1) belt use, 2) seated position with respect to the lead side in the rollover, 3) another front occupant in the crash, and 4) number of quarter rolls. The aim was to improve our understanding of rollover injury mechanisms. METHOD: Rollover accidents were analyzed using 1992-2004 NASS-CDS data. The sample included adult drivers and right-front passengers. All occupants were evaluated and then a subset of non-ejected occupants was analyzed. Using roll direction and seating position, the sample was divided into near- and far-seated occupants. Injury and fatality risks were determined by seatbelt use, occupancy, rollover direction, and number of quarter rolls. Risk was defined as the number of injured (e.g., MAIS 3+) divided by the number of exposed occupants (MAIS 0-6). Significance in differences was determined. A matched-pair analysis was used to determine the risk of serious injury for near- and far-seated occupants who were either belted or unbelted in the same crash. RESULTS: For all occupants, serious injury risks were highest for far-seated, unbelted occupants at 18.1% +/- 4.8%, followed by near-seated unbelted occupants at 12.0% +/- 3.5%. However, the difference was not statistically significant. Belted near- and far-seated occupants had a similar injury risk of 4.3% +/- 1.2% and 4.0% +/- 1.2%, respectively. For non-ejected occupants, serious injury risk was 9.5% +/- 3.2% for far-seated unbelted occupants and 4.9% +/- 2.1% for near-seated unbelted occupants, not a statistically significant difference. Serious injury risk was similar for belted near- and far-seated non-ejected occupants, at 3.6% +/- 1.1%. Seatbelts were 64.2%-77.9% effective in preventing serious injury for all occupants and 62.1%-26.5% for far- and near-seated, non-ejected occupants, respectively. Based on the matched pairs, seatbelts were less effective for near-seated (5.0%) compared to far-seated (2.8%) occupant MAIS 3+F risks. This was similar for non-ejected occupants. An unbelted near-seated occupant increased the risk for a belted far-seated occupant by 2.2 times, whereas an unbelted far-seated occupant increased the risk for a belted near-seated occupant by 10.2 times. For all occupants, the risk of serious injury increased with the number of quarter rolls, irrespective of seated position. For near-seated occupants, seatbelt effectiveness was higher in < or =1 roll than 1+ roll, at 72.3% compared to 28.3%. For far-seated occupants, seatbelt effectiveness was similar in < or =1 and 1+ roll samples at 78.3% and 76.8%, respectively. Near-seated occupants had the lowest serious injury risk when they were the sole occupant in the vehicle. This was also true for non-ejected occupants. However, far-seated occupants had a lower injury risk when another occupant was involved in the crash. CONCLUSIONS: The effect of carrying another occupant appears to reduce the risk of serious injury to far-seated occupants. However, near-seated occupants are better off being the sole occupant in the vehicle. Seatbelt effectiveness was lowest at 28.3% for non-ejected, near-seated occupants in 1+ rolls. This finding deserves further evaluation in an effort to improve seatbelt effectiveness in rollovers. For belted drivers alone in a rollover, fatality risks are 2.24 times higher for the far- versus near-seated position. Analysis of rollovers by quarter turns indicates that occupants are both far-side and near-side in rollovers. The extent to which this confounds the relationship between roll direction, seating position, and injury risk is unknown.     

Detection and identification of baculovirus pesticides by multitemperature single-strand conformational polymorphism

The method of single-strand conformational polymorphism (SSCP) was modified in our laboratories for the characterization of baculoviruses, insect viruses with great potential for use as bioinsecticides in biological protection programs. A series of primers were synthesized after the comparison of the polyhedrin gene sequences of over 20 baculoviruses. Polyhedrin is a highly conserved protein which is responsible for the persistence of the virus in the environment. Universal primers were designed which could be used in polymerase chain reactions (PCR) containing genomic DNA from an array of nucleopolyhedrosis viruses (NPVs) including these which are used as biopesticides against important pests of forests and crops, such as Anticarsia gemmatalis, Spodoptera frugiperda, Lymantria dispar, Lymantria monacha and many others. PCR products were denatured and subjected to single-strand DNA electrophoresis at variable temperatures (MSSCP) where, after silver staining, they gave ssDNA band patterns characteristic for each baculovirus species. This technique can be potentially applied to detect baculoviruses in insects collected in the field, as well as to plant tissues and the excrements or bodies of predators without need for sequencing the PCR products. Sometimes MSSCP can be used not only for species determination but also as an indication of genomic variability which can be related to infectivity.     

Sensitivity of two dispersion models (AERMOD and ISCST3) to input parameters for a rural ground-level area source

As of December 2006, the American Meteorological Society/U.S. Environmental Protection Agency (EPA) Regulatory Model with Plume Rise Model Enhancements (AERMOD-PRIME; hereafter AERMOD) replaced the Industrial Source Complex Short Term Version 3 (ISCST3) as the EPA-preferred regulatory model. The change from ISCST3 to AERMOD will affect Prevention of Significant Deterioration (PSD) increment consumption as well as permit compliance in states where regulatory agencies limit property line concentrations using modeling analysis. Because of differences in model formulation and the treatment of terrain features, one cannot predict a priori whether ISCST3 or AERMOD will predict higher or lower pollutant concentrations downwind of a source. The objectives of this paper were to determine the sensitivity of AERMOD to various inputs and compare the highest downwind concentrations from a ground-level area source (GLAS) predicted by AERMOD to those predicted by ISCST3. Concentrations predicted using ISCST3 were sensitive to changes in wind speed, temperature, solar radiation (as it affects stability class), and mixing heights below 160 m. Surface roughness also affected downwind concentrations predicted by ISCST3. AERMOD was sensitive to changes in albedo, surface roughness, wind speed, temperature, and cloud cover. Bowen ratio did not affect the results from AERMOD. These results demonstrate AERMOD's sensitivity to small changes in wind speed and surface roughness. When AERMOD is used to determine property line concentrations, small changes in these variables may affect the distance within which concentration limits are exceeded by several hundred meters.     

Single-source impact analysis using three-dimensional air quality models

Isolating the effects of an individual emissions source on secondary air pollutants such as ozone and some components of particulate matter must incorporate complex nonlinear processes, be sensitive to small emissions perturbations, and account for impacts that may occur hundreds of kilometers away. The ability to evaluate these impacts is becoming increasingly important for efficient air quality management. Here, as part of a recent compliance enforcement action for a violation of the Clean Air Act and as an evaluation of ozone response to single-source emissions plumes, two three-dimensional regional photochemical air quality models are used to assess the impact on ozone from approximately 2000 to 3000 excess t/month of nitrogen oxides emitted from a single power plant in Ohio. Periods in May, July, and August are evaluated. Two sensitivity methods are applied: the "brute-force" (B-F) method and the decoupled direct method (DDM). Using DDM, maximum 1-hr averaged ozone concentrations are found to increase by up to 1.8, 1.3, and 2.2 ppbv during May, July, and August episodes, respectively, and concentration increases greater than 0.5 ppbv occur in Ohio, Pennsylvania, Maryland, New York, West Virginia, Virginia, and North and South Carolina. B-F results for the August episode show a maximum 1-hr averaged ozone concentration increase of 2.3 ppbv. Significant localized decreases are also simulated, with a maximum of 3.6 ppbv in Ohio during the August episode and decreases of 0.50 ppbv and greater in Ohio, Pennsylvania, Maryland, West Virginia, and Virginia. Maximum increases are compared with maximum decreases for the August period using second-order DDM and are found, in aggregate, to be greater in magnitude by 42%. When evaluated during hours when ozone concentrations exceed 0.060 ppm, the maximum increases in ozone are higher than decreases by 82%. The spatial extent of ozone increase in both cases is about triple that of reduction.     

Effects of repeated exposure to malathion on growth, food consumption, and locomotor performance of the western fence lizard (Sceloporus occidentalis)

Effects of repeated pollutant exposure on growth, locomotor performance, and behavior have rarely been evaluated in reptiles. We administered three doses of malathion (2.0, 20, or 100mg/kg body weight) to western fence lizards (Sceloporus occidentalis) over an 81day period. Eight and 23% mortality occurred at 20 and 100mg/kg (p=0.079) and 85% of lizards in the 100mg/kg group exhibited clinical symptoms of poisoning. Growth, food consumption, body condition index, and terrestrial locomotor performance were not significantly influenced by malathion. However, arboreal sprint velocity was significantly reduced in lizards receiving 100mg/kg. Fifty percent of lizards in the 100mg/kg group also refused to sprint in the arboreal setting (p=0.085). Based on these results, arboreal locomotor performance was the most sensitive metric of exposure we evaluated. Further study of compounds such as malathion is warranted due to highly variable application rates and exposure scenarios.     

Protection of ash (Fraxinus excelsior) trees from ozone injury by ethylenediurea (EDU): roles of biochemical changes and decreased stomatal conductance in enhancement of growth

Treatments with ethylenediurea (EDU) protect plants from ozone foliar injury, but the processes underlying this protection are poorly understood. Adult ash trees (Fraxinus excelsior), with or without foliar ozone symptoms in previous years, were treated with EDU at 450ppm by gravitational trunk infusion in May-September 2005 (32.5ppmh AOT40). At 30-day intervals, shoot growth, gas exchange, chlorophyll a fluorescence, and water potential were determined. In September, several biochemical parameters were measured. The protective influence of EDU was supported by enhancement in the number of leaflets. EDU did not contribute its nitrogen to leaf tissue as a fertiliser, as determined from lack of difference in foliar N between treatments. Both biochemical (increase in ascorbate-peroxidase and ascorbic acid, and decrease in apoplastic hydrogen peroxide) and biophysical (decrease in stomatal conductance) processes regulated EDU action. As total ascorbic acid increased only in the asymptomatic trees, its role in alleviating O(3) effects on leaf growth and visible injury is controversial.     

Deactivation of titanium dioxide photocatalyst by oxidation of polydimethylsiloxane and silicon sealant off-gas in a recirculating batch reactor

We have studied deactivation of titanium dioxide (TiO2) photocatalyst by oxidation of polydimethylsiloxane and silicone sealant off-gas in a recirculating batch reactor. Polydimethylsiloxane vapor is a model indoor air pollutant. It does not adsorb strongly on TiO2 in the dark, but undergoes oxidation when the ultraviolet (UV) photons are also present. Commercial silicone (room-temperature vulcanizing) sealant off-gas is an actual indoor air pollutant subject to short-term spikes in concentration. It does adsorb on the TiO2 surface in the dark, but UV photons also catalyze its oxidation. The oxidation of the Si-containing vapors was monitored using a Fourier transform infrared spectroscope equipped with a gas cell. Subsequent to each incremental exposure, a hexane oxidation reaction was performed to track the titania catalyst's activity. The exposures were repeated until substantial deactivation was achieved. We have also documented the regenerative effect of washing the catalyst surface with water. Surface science techniques were used to view the topography of the catalyst and to identify the elements causing the deactivation. Procedural observations of interest in the context of our recirculating batch reactor include the following: the rate of oxidation of hexane was used to assess the activity of a photocatalyst sample; hexane is an appropriate choice of a probe molecule because it does not adsorb in the dark and it undergoes photocatalytic oxidation (PCO) completely, forming CO2; and hexane does not deactivate the photocatalyst surface.     

Preliminary evidence of a decline in perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) concentrations in American Red Cross blood donors

The purpose of this pilot study was to determine whether perfluorooctanesulfonate (PFOS,C(8)F(17)SO(3)(-)) and perfluorooctanoate (PFOA,C(7)F(15)CO(2)(-)) concentrations in American Red Cross blood donors from Minneapolis-St. Paul, Minnesota have declined after the 2000-2002 phase-out of perfluorooctanesulfonyl-fluoride (POSF, C(8)F(17)SO(2)F)-based materials by the primary global manufacturer, 3M Company. Forty donor plasma samples, categorized by age and sex, were collected in 2005, and PFOS and PFOA concentrations were compared to 100 (non-paired) donor serum samples collected in 2000 from the same general population that were analyzed at the time using ion-pair extraction methods with tetrahydroperfluorooctanesulfonate as an internal standard. Eleven of the 100 samples originally collected were reanalyzed with present study methods that involved (13)C- labeled PFOA spiked into the donor samples, original samples, control human plasma, and the calibration curve prior to extraction, and was used as a surrogate to monitor extraction efficiency. Quantification was performed by high performance liquid chromatography tandem mass spectrometry methods. Among the 100 serum samples analyzed for PFOS, the geometric mean was 33.1 ng ml(-1) (95% CI 29.8-36.7) in 2000 compared to 15.1 ng ml(-1) (95% CI 13.3-17.1) in 2005 (p<0.0001) for the 40 donor plasma samples. The geometric mean concentration for PFOA was 4.5 ng ml(-1) (95% CI 4.1-5.0) in 2000 compared to 2.2 ng ml(-1) (95% CI 1.9-2.6) in 2005 (p<0.0001). The decrease was consistent across donors' age and sex. To confirm these preliminary findings, additional sub-sets of year 2000 samples will be analyzed, and a much larger biomonitoring study of other locations is planned.     

Catalytic hydrogenation of polyaromatic hydrocarbon (PAH) compounds in supercritical carbon dioxide over supported palladium

A series of supported palladium catalysts were evaluated for their ability to mediate the complete hydrogenation of polycyclic aromatic hydrocarbon (PAH) compounds. Benzo[a]pyrene (B[a]P) or phenanthrene (Phe) in hexane was merged with a hydrogen-carbon dioxide [5% (w/w) H(2)/CO(2)] stream and transferred to a flow through mini-reactor (capacity ca. 1 g) that was maintained at 90 degrees C under a back-pressure of 20.68 MPa. Effluent from the reactor trapped in hexane was monitored/quantified by gas chromatography-mass spectrometry. Catalyst formulations supported on iron powder, high density polyethylene (HDPE) or gamma-alumina were prepared and compared in terms of hydrogenation activity as measured by the quantity of substrate per unit time that could be perhydrogenated to toxicologically innocuous products. Both of the Pd preparations supported on gamma-alumina were more efficient than a commercial Pd(0) (5% w/w) on gamma-Al(2)O(3) formulation or preparations supported on HDPE or the iron powder. Bimetallic mixtures with Pd increased the hydrogenation activity when co-deposited with Cu or Ni but not with Ag or Co. However, increases in hydrogenation activity by increasing the loading of Pd (or bimetallic mixture) on this surface were limited. Despite using supercritical carbon dioxide (scCO(2)) to swell the surfaces of the polymer, the deposition of nanoparticles within the polyethylene formulation was appreciably less active than either the oxidic or the Fe(0) formulations.