Comparative personal exposures to organic dusts and endotoxin.
The aims of the study were to provide valid comparative data for personal exposures to dust and endotoxins for different occupations and to calculate comparative data for the contamination of organic dusts with endotoxin. Nine different occupational settings were studied, drawn from the textile, agricultural and animal handling industries. Samples were collected by personal sampling techniques, using the Institute of Occupational Medicine (IOM) sampling head, glass fibre filters and rechargeable sampling pumps. The dust exposures were calculated by gravimetric analysis and using the calculated volume of air sampled were expressed as mg/m3. Endotoxin exposures were measured using a simple water extraction from the collected dusts, followed by a quantitative turbidimetric assay. Results were expressed as ng/m3, using the calculated volume of air sampled. In addition, the levels of the contamination of dusts with endotoxin for individual industries were expressed as ng/mg of collected dust. Two hundred and fifty-nine samples, collected from 9 different industries and across 36 different sites were analysed. This represented a sampling rate of 25% for the total work force. The average sampling time was 4.62 h. For all the dusts collected, a significant correlation between the collected dust and endotoxin was seen (r = 0.7 and p < 0.001). The highest dust exposures occurred during cleaning activities (grain handling: 72.5 mg/m3). The individuals exposed to the highest median level of dust and endotoxin were the animal handlers (poultry handlers, dust: 11.53 mg/m3, endotoxin: 71,995 ng/m3). Weaving and mushroom cultivation had the lowest exposures for dust and endotoxins. The mostly highly contaminated dusts (median values expressed as ng of endotoxin per mg of collected dust) were found in the animal handling (poultry: 1,030 ng/mg, swine: 152 ng/mg) and cotton spinning (522 ng/mg) industries. Processing of cotton and wool fibres was found to reduce the levels of contamination of dusts with endotoxin. In the study, valid comparative data for personal exposures to organic dusts and endotoxins have been presented. The highest exposures were found amongst animal handlers and during cleaning activities. The results highlight that dust exposures are greater in a number of industries than the set exposure standards. In addition, endotoxin exposures are found to be greater than levels at which harmful effects have been demonstrated. (+info)
Toxicity of combustion products from burning polymers: development and evaluation of methods.
Laboratory and room-scale experiments were conducted with natural and synthetic polymers: cotton, paper, wood, wool, acetate, acrylic, nylon, and urethane. Smoke and off-gases from single materials were generated in a dual-compartment 110-liter exposure chamber. Multicomponent, composite fuel loads were burned within a 100 m(3) facility subdivided into rooms. In chamber experiments, mortality depended on the amount of material burned, i.e., fuel consumption (FC). Conventional dose (FC)/mortality curves were obtained, and the amount of fuel required to produce 50% mortality (FC(50)) was calculated. With simple flame ignition, cotton was the only material that produced smoke concentrations lethal to rats; FC(50) values for cotton ranged from 2 g to 9 g, depending on the configuration of the cotton sample burned. When supplemental conductive heat was added to flame ignition, the following FC(50) values were obtained; nylon, 7 g; acrylic, 8 g; newsprint, 9 g; cotton, 10 g; and wood, 11 g. Mortality resulting from any given material depended upon the specific conditions employed for its thermal decomposition. Toxicity of off-gasses from pyrolysis of phosphorus-containing trimethylol propane-polyurethane foams was markedly decreased by addition of a flame ignition source. Further studies are needed to determine the possible relevance of single-material laboratory scale smoke toxicity experiments. Room-scale burns were conducted to assess the relative contributions of single materials to toxicity of smoke produced by a multicomponent self-perpetuating fire. Preliminary results suggest that this approach permits a realistic evaluation of the contribution of single materials to the toxicity of smoke from residential fires. (+info)
Survival of enterococci and staphylococci on hospital fabrics and plastic.
The transfer of gram-positive bacteria, particularly multiresistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), among patients is a growing concern. One critical aspect of bacterial transfer is the ability of the microorganism to survive on various common hospital surfaces. The purpose of this study was to determine the survival of 22 gram-positive bacteria (vancomycin-sensitive and -resistant enterococci and methicillin-sensitive and -resistant staphylococci) on five common hospital materials: smooth 100% cotton (clothing), 100% cotton terry (towels), 60% cotton-40% polyester blend (scrub suits and lab coats), 100% polyester (privacy drapes), and 100% polypropylene plastic (splash aprons). Swatches were inoculated with 10(4) to 10(5) CFU of a microorganism, assayed daily by placing the swatches in nutritive media, and examining for growth after 48 h. All isolates survived for at least 1 day, and some survived for more than 90 days on the various materials. Smaller inocula (10(2)) survived for shorter times but still generally for days. Antibiotic sensitivity had no consistent effect on survival. The long survival of these bacteria, including MRSA and VRE, on commonly used hospital fabrics, such as scrub suits, lab coats, and hospital privacy drapes, underscores the need for meticulous contact control procedures and careful disinfection to limit the spread of these bacteria. (+info)
Acceptance and use of communal filtration units in guinea worm eradication.
The use of cloth to filter drinking water for guinea worm prevention is a long-standing control strategy and part of a mixed approach that includes the provision of wells, chemical treatment of ponds and protection of water supplies. As the goal of eradication nears, filters are a useful component of the quick response needed to implement case containment at village level. Various designs of filters have been used. Individual hand-sewn filters (HSFs) using monofilament nylon cloth have played a central role in village-based control to date. Problems such as the need to continually reinforce correct habitual filtering behaviour have led to the design and testing of communal filtration units (CFUs) made from metal oil drums with filter cloth inserted in the top and spigots at the bottom. Approximately one year after the introduction of CFUs in the South-western Zone of Nigeria, village surveys were conducted to determine opinions about the two types of filters and reported use. Percentage use was calculated by dividing the number of times water was filtered in the week preceding the survey by the number of times water was collected in that week. Those respondents with access to CFUs filtered an average of 91.9% of the time compared to 75.7% of those with HSFs. Using the village as level of analysis since it was the main level of intervention, the average percent of times villagers in CFU villages filtered was 91.1% compared to 77.8% in HSF villages. Although CFUs were more expensive in the short run, their greater acceptance by villagers is a factor to recommend their wider implementation to speed up elimination of guinea worm from Nigeria. (+info)
Nitrile hydratase and amidase from Rhodococcus rhodochrous hydrolyze acrylic fibers and granular polyacrylonitriles.
Rhodococcus rhodochrous NCIMB 11216 produced nitrile hydratase (320 nkat mg of protein(-1)) and amidase activity (38.4 nkat mg of protein(-1)) when grown on a medium containing propionitrile. These enzymes were able to hydrolyze nitrile groups of both granular polyacrylonitriles (PAN) and acrylic fibers. Nitrile groups of PAN40 (molecular mass, 40 kDa) and PAN190 (molecular mass, 190 kDa) were converted into the corresponding carbonic acids to 1.8 and 1.0%, respectively. In contrast, surfacial nitrile groups of acrylic fibers were only converted to the corresponding amides. X-ray photoelectron spectroscopy analysis showed that 16% of the surfacial nitrile groups were hydrolyzed by the R. rhodochrous enzymes. Due to the enzymatic modification, the acrylic fibers became more hydrophilic and thus, adsorption of dyes was enhanced. This was indicated by a 15% increase in the staining level (K/S value) for C. I. Basic Blue 9. (+info)
Decolorization and detoxification of textile dyes with a laccase from Trametes hirsuta.
Trametes hirsuta and a purified laccase from this organism were able to degrade triarylmethane, indigoid, azo, and anthraquinonic dyes. Initial decolorization velocities depended on the substituents on the phenolic rings of the dyes. Immobilization of the T. hirsuta laccase on alumina enhanced the thermal stabilities of the enzyme and its tolerance against some enzyme inhibitors, such as halides, copper chelators, and dyeing additives. The laccase lost 50% of its activity at 50 mM NaCl while the 50% inhibitory concentration (IC(50)) of the immobilized enzyme was 85 mM. Treatment of dyes with the immobilized laccase reduced their toxicities (based on the oxygen consumption rate of Pseudomonas putida) by up to 80% (anthraquinonic dyes). Textile effluents decolorized with T. hirsuta or the laccase were used for dyeing. Metabolites and/or enzyme protein strongly interacted with the dyeing process indicated by lower staining levels (K/S) values than obtained with a blank using water. However, when the effluents were decolorized with immobilized laccase, they could be used for dyeing and acceptable color differences (DeltaE*) below 1.1 were measured for most dyes. (+info)
Strike-through of moist contamination by woven and nonwoven surgical materials.
A test is described which correlates the stress of stretching surgical gown and drape material with moist bacterial strike-through. By application of this test to a number of woven and nonwoven surgical gown and drape materials, it was found that not all of these materials, either woven or nonwoven, are impermeable to moist contamination for equal periods of time. Nonwoven disposable materials now in use range from those which remain impermeable to moist bacterial permeation through all tests while some remain impermeable for limited periods of time, and others almost immediately permeable to moist bacterial penetration. The same situation holds for woven materials. Under conditions of our test, Quarpel treated Pima tight-woven cotton cloth was impermeable to moist bacterial strike-through, through up to 75 washing and sterilizing cyclings, while ordinary linen and untreated Pima cloth permitted bacterial permeation almost immediately. These results have significance in lengthy wet surgical operations. (+info)
Cloning and promoter analysis of the cotton lipid transfer protein gene Ltp3(1).
A cotton Ltp3 gene and its 5' and 3' flanking regions have been cloned with a PCR-based genomic DNA walking method. The amplified 2.6 kb DNA fragment contains sequences corresponding to GH3 cDNA which has been shown to encode a lipid transfer protein (LTP3). The gene has an intron of 80 bp which is located in the region corresponding to the C-terminus of LTP3. The Ltp3 promoter was systematically analyzed in transgenic tobacco plants by employing the Escherichia coli beta-glucuronidase gene (GUS) as a reporter. The results of histochemical and fluorogenic GUS assays indicate that the 5' flanking region of the Ltp3 gene contains cis-elements conferring the trichome specific activity of Ltp3 promoter. (+info)