Duplex criteria for in-stent restenosis in the superficial femoral artery.

OBJECTIVES: To elucidate the optimal cutoff and accuracy of duplex ultrasonography (DUS) parameters for in-stent restenosis (ISR) after nitinol stenting in the superficial femoral artery (SFA). BACKGROUND: Few data are available regarding the performance of DUS for binary ISR based on quantitative vessel analysis (QVA) in the era of SFA nitinol stenting. METHODS: This retrospective study included 74 in-stent stenoses of SFA who underwent DUS before follow-up angiography. DUS parameters, such as peak systolic velocity (PSV) and the peak systolic velocity ratio (PSVR), were compared with percent diameter stenosis (%DS) from a QVA basis. RESULTS: There was a statistically significant correlation (P < 0.001) between "%DS and PSV" and "%DS and PSVR," and the correlation with %DS proved to be stronger in PSVR (R = 0.720) than in PSV (R = 0.672). The best performing parameter for ISR (50% or greater stenosis) was revealed PSVR, as the areas under the receiver operator characteristics curves using PSVR and PSV were 0.908 and 0.832, respectively. A PSVR cut off value of 2.85 yielded the best predictive value with sensitivity of 88%, specificity of 84%, and accuracy of 86%. The positive predictive value was 85% and the negative predictive value was 88%. CONCLUSIONS: A PSVR of 2.85 is the optimal threshold for ISR after nitinol stenting in the SFA. Further large prospective studies are required for the validation and establishment of uniform criteria for DUS parameters.

Emission fluxes of styrene monomers and other chemicals for products containing expanded polystyrene beads.

Styrene in indoor air can adversely affect human health. In this study, styrene monomer and other chemical emission fluxes for products containing expanded polystyrene beads (pillows, cushions, and soft toys) were measured at various temperatures to simulate typical product use. The contributions of the products to styrene and other chemical concentrations in indoor air and human exposure to these chemicals were estimated, and health risk assessments were performed. The styrene monomer emission fluxes for the samples at 25°C were between 25.3 and 8.73×103 µg/(m2 h). The styrene emission fluxes for the product surfaces increased strongly as the temperature increased, from between 124 and 2.44×104 µg/(m2 h) at 36°C (simulating human body temperature) to between 474 and 4.59×104 µg/(m2 h) at 50°C (simulating inside an automobile in summer). The hexane, heptane, toluene, octane, ethylbenzene, m- and p-xylene, o-xylene, and dodecane emission fluxes at 25°C for the sample that emitted the analytes most readily were high. The maximum estimated styrene and xylene concentrations in indoor air caused by emissions from expanded polystyrene beads at 36°C in a bedroom and automobile were higher than the relevant guidelines. The maximum contribution of a product containing expanded polystyrene beads in a living room, bedroom, or automobile could cause the total volatile organic compound concentration in air to exceed the advisable value (400 µg/m3). The estimated maximum hazard quotients for styrene, toluene, and xylene emitted by a product containing expanded polystyrene beads at 36°C in a bedroom were 0.59, 0.30, and 0.37, respectively. These non-carcinogenic risk values for single products could contribute to the non-carcinogenic risk thresholds being exceeded when multiple products and other sources of chemicals are taken into consideration. The estimated styrene concentrations suggest that products containing expanded polystyrene beads are important sources of styrene to indoor air.

Compositions of volatile organic compounds emitted from melted virgin and waste plastic pellets.

To characterize potential air pollution issues related to recycling facilities of waste plastics, volatile organic compounds (VOCs) emitted from melted virgin and waste plastics pellets were analyzed. In this study, laboratory experiments were performed to melt virgin and waste plastic pellets under various temperatures (150, 200, and 250 degrees C) and atmospheres (air and nitrogen [N2]). In the study presented here, low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS) and the recycled waste plastic pellets were used. The VOCs generated from each plastic pellets were collected by Tenax/Carboxen adsorbent tubes and analyzed by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS). The result showed the higher temperatures generated larger amounts of total VOCs (TVOCs). The VOCs emitted from the virgin plastic pellets likely originated from polymer degradation. Smaller TVOC emissions were observed in N2 atmosphere than in air atmosphere. In particular, larger amounts of the oxygenated compounds, which are generally hazardous and malodorous, were detected in air than in N2. In addition to the compounds originating from polymer degradation, the compounds originating from the plastic additives were also detected from LDPE and PS. Furthermore, various species of VOCs likely originating from contaminant inseparate polyvinyl chloride (PVC), food residues, cleaning agents, degreasers, and so on were detected from the waste plastic. Thus, melting waste plastics, as is conducted in recycling facilities, might generate larger amounts of potentially toxic compounds than producing virgin plastics.

Does open-air exposure to volatile organic compounds near a plastic recycling factory cause health effects?

OBJECTIVES: After a plastic reprocessing factory began to operate in August 2004, the residents around the factory in Neyagawa, Osaka, Japan, began to complain of symptoms. Therefore, we conducted an exposure assessment and a population-based epidemiological study in 2006. METHODS: To assess exposure, volatile organic compounds (VOCs) and total VOCs were measured at two locations in the vicinity of the factory. In the population-based study, a total of 3,950 residents were targeted. A self-administered questionnaire was used to collect information about subjects' mucocutaneous or respiratory symptoms. Using logistic regression models, we compared the prevalence of symptoms in July 2006 by employing the farthest area from the factory as a reference, and prevalence odds ratios (PORs) and their 95% confidence intervals (CIs) were estimated. RESULTS: The concentration of total VOCs was higher in the vicinity of the factory. The prevalence of mucocutaneous and respiratory symptoms was the highest among the residents in the closest area to the factory. Some symptoms were significantly increased among the residents within 500 m of the factory compared with residents of an area 2800 m from the factory: e.g., sore throat (POR=3.2, 95% CI: 1.3-8.0), eye itch (POR=3.0, 95% CI: 1.5-6.0), eye discharge (POR=6.0, 95% CI: 2.3-15.9), eczema (POR=3.0, 95% CI: 1.1-7.9) and sputum (POR=2.4, 95% CI: 1.1-5.1). CONCLUSIONS: Despite of the limitations of this study, these results imply a possible association of open-air VOCs with mucocutaneous and respiratory symptoms. Because this kind of plasticre cycling factory only recently came into operation, more attention should be paid to the operation of plastic recycling factories in the environment.