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PubMed1983

Prospective randomised comparison of photocoagulation and rubber band ligation in treatment of haemorrhoids.

Two hundred and sixty eight patients with haemorrhoids were allocated at random to treatment by either photocoagulation (group 1, n=141) or rubber band ligation (group 2, n=127) and followed up for one year. There was no significant difference in the symptomatic outcome of treatment between the two groups at one, four, or 12 months, irrespective of whether first or second degree haemorrhoids were treated. Side effects of treatment (bleeding or severe pain) were significantly more common after rubber band ligation (n=11) than after photocoagulation (n=2; p less than 0.01). Further outpatient treatment, however, was required significantly more often after photocoagulation (n=23) than rubber band ligation (n=6) (p greater than 0.02), and 19 patients (14 in group 1 and five in group 2; NS) subsequently had a haemorrhoidectomy. At one year 26 of 103 patients were dissatisfied after photocoagulation compared with 20 of 88 after rubber band ligation. Photocoagulation is a safe and comfortable treatment which gives long term results that are as good as those of rubber band ligation. Complications are more common after rubber band ligation, but further treatment is required more commonly after photocoagulation.

Adolescent↗
PubMed1980

Sustained release of niridazole from silicone rubber implants for the treatment of Schistosoma mansoni infections.

Niridazole was incorporated into silicone rubber implants to investigate the potential of a sustained release of the drug in the therapy of murine schistosomiasis mansoni. The infected animals (200 cercariae for 6 weeks) were randomly divided into three groups: one group received silicone rubber implants containing 50% by weight niridazole; a second group received blank silicone rubber implants with no drug; and the third group received no implants. Mortality 4 weeks later was in excess of 80% for animals with no implants or with the blank silicone rubber implants. In contrast, 10% mortality was observed in the mice receiving the niridazole-silicone rubber implants over a 10-week period. The worm burden in the niridazole-silicone rubber implant group was reduced at 10 weeks post implantation by 77%.

Animals↗
PubMed2000

Mortality among rubber chemical manufacturing workers.

BACKGROUND: A retrospective cohort mortality study evaluated ischemic heart disease (IHD) among workers in the "rubber chemicals" manufacturing department of a Western New York plant. A previous study at the plant found elevated chest pain and angina among workers in this department. METHODS: Mortality experience of workers employed from 1946-1988 was followed through December 31, 1994. Mortality was compared to U.S. population rates and to local Niagara county rates by using the NIOSH life table analysis system. Poisson regression was used to examine patterns of IHD within the cohort. RESULTS: The standardized mortality ratio (SMR) for IHD among workers in the rubber chemicals department was 1.51 (U.S. rates) and 1.19 (Niagara county rates). Increased mortality from IHD in the rubber chemicals department was most pronounced at younger ages (< 50, SMR = 2.4); workers in a second chemical production department also had an elevated (but not statistically significant) SMR of 1.5 for IHD. CONCLUSIONS: IHD mortality among workers in the rubber chemicals department was elevated, particularly among those under 50 years of age. Potential occupational risk factors for IHD include the rotating shift pattern for employees assigned to two chemical production departments and chemical exposures present in the rubber chemicals department.

Adolescent↗
PubMed1985

Mortality among rubber workers: X. Reclaim workers.

This study evaluated the mortality experience of 1,352 white and 438 nonwhite men who worked in the rubber-reclaiming division of a large rubber manufacturing company. In comparisons of mortality of white reclaim workers with that of nonreclaim workers rate ratios were 2.7 for esophageal cancer (six observed deaths among reclaim workers), 2.1 for bladder cancer (seven observed deaths), and 4.5 for multiple myeloma (six observed deaths). The excess of bladder cancer among white reclaim workers may be associated with their employment in other high-risk areas of the plant, whereas no such explanation was found for the excesses of esophageal cancer and multiple myeloma. Overall, the lung cancer mortality rate of white reclaim workers was similar to the rate of US white males and other white rubber workers. There was a 50% excess of lung cancer deaths among nonwhite reclaim workers compared with other nonwhite rubber workers. However, this observation is based on small numbers, and no firm conclusions can be reached about the risk of lung cancer associated with reclaim operations in this group of rubber workers.

Esophageal Neoplasms↗
PubMed2002

Urothelial cell DNA adducts in rubber workers.

Workers employed in the rubber industry appear to have a significant excess cancer risk in a variety of sites, including cancer of the urinary bladder. In this cross-sectional study, we investigated the occurrence of DNA adducts in exfoliated bladder cells of currently exposed, nonsmoking rubber workers (n = 52) and their relationship with occupational exposure estimates and acetylation phenotype (NAT2). Four DNA adducts were identified, with the proportion of positive samples (e.g., DNA samples with quantifiable levels of a specific DNA adduct) ranging from 3.8 to 79%. The highest proportion of positive samples and the highest relative adduct labeling levels were in workers involved in the production functions "mixing" and "curing," areas with potential for substantial exposure to a wide range of chemical compounds used in rubber manufacturing (P < 0.05 for adducts 2 and/or 3, compared to all other departments). No statistically significant relationships were found between identified DNA adducts and urinary mutagenicity or personal inhalable and dermal exposure estimates. Interestingly, subjects with a fast NAT2 acetylation phenotype tended to have higher levels of DNA adducts. This study suggests that rubber workers engaged in mixing and curing may be exposed to compounds that can form DNA adducts in urothelial cells. Larger studies among rubber workers should be conducted to study in more detail the potential carcinogenicity of exposures encountered in these work areas.

Acetylation↗
PubMedDate not supplied

Degradation of the rubber in truck tires by a strain of Nocardia.

A strip of tread compound cut from a truck tire was degraded only slightly when it was used as the sole growth substrate for a strain of Nocardia. On the contrary, its degradation was markedly enhanced by addition of a strip cut from a latex glove which the organism readily utilized as a growth substrate. When a glove strip was added, the biomass concentration in the experimental flask became more than 10-fold higher than the control without a glove strip and the colonization of the tire strip was significantly enhanced. After 8 weeks' cultivation, about 28% of the tire strip was disintegrated into very small black particles (mostly less than 30 microns in diameter) and the weight of the remaining unchanged portion of the strip was about 49% of the initial weight. Four kinds of truck tire treads were attacked in differing degrees by the organism under the same conditions. The treads containing more than 70 phr (parts per hundred of rubber) of natural rubber were considerably attacked, while those with a natural rubber content of less than 55 phr were attacked only slightly. The microbial activity against the rubber in the side wall of a truck tire was relatively high, but the inner liner was hardly attacked and the bead rubber not at all.

Biodegradation, Environmental↗
PubMed1991

Chemicals used in the rubber industry.

Hundreds of chemicals and mixtures illustrative of many structural and use categories are employed in the rubber industry. Global utilization of natural rubber and synthetic elastomers as well as rubber-processing chemicals are projected to increase in the foreseeable future. Primary focus is centered on the major rubber processing chemicals and elastomer monomers in regard to their utility, production trends, structural characteristics, nature of potential impurities, and toxicology (primarily carcinogenicity and genotoxicity). Additionally, areas of specific exposure concern and epidemiology in the rubber industry are considered.

Animals↗
PubMed1979

Rubber solvent: a clastogenic agent that fails to induce sister-chromatid exchanges.

Rubber solvent was tested for its ability to induce chromosome aberrations and sister-chromatid exchanges in human whole blood cultures. Following exposure to relatively low rubber solvent concentrations (0.0125% and greater) significant increases in the frequencies of chromatid gaps and breaks were observed. At higher rubber-solvent concentrations (0.05% and greater) there were also significant increases in the frequency of chromosome breaks. In contrast to the increase in chromosome aberrations following rubber-solvent exposure, rubber-solvent concentrations up to the toxic level failed to produce increases in the sister-chromatid exchange frequency.

Cells, Cultured↗
PubMed2005

Rubber additives induce oxidative stress in rainbow trout.

Several studies have demonstrated the toxicity of rubber leachate, mainly from rubber tires, to aquatic organisms. In the present study rainbow trout (Oncorhynchus mykiss) were exposed to water provided to aquaria through a rubber hose. Increased hepatic ethoxyresorufin-O-deethylase (EROD) activity, and glutathione reductase (GR) activity were observed in the exposed fish. Two common rubber additives, 2-mercaptobenzothiazole (MBT) and diphenylamine (DPA) and structurally related compounds, were identified by chemical analyses of water samples as were hydroxylated polycyclic aromatic hydrocarbons. Metabolites of these compounds were also detected in the bile of exposed fish, as were some of the parent compounds. In a following experiment, we injected rainbow trout with DPA or MBT. Both compounds affected total glutathione (tGSH) concentration in liver and MBT caused an increase in hepatic GR and glutathione S-transferase (GST) activity as well. In DPA injected fish, hydroxylated DPA was the main metabolite in the bile. Our results indicate that rubber chemicals may leach into the water surroundings where they can be taken up and metabolised by fish. Some of these chemicals can lead to up-regulation of antioxidant defences as demonstrated with DPA and MBT injections.

Analysis of Variance↗
PubMed2005

The use of smoke acid as an alternative coagulating agent for natural rubber sheets' production.

A comparative study of rubber sheets obtained using formic, acetic, and smoke acid as coagulants is shown for latex obtained from native Amazonian trees and also from commercial cultivated trees. The evaluation of both processes of coagulation was carried out by spectroscopic and physical-chemical analysis, showing no differences in the rubber sheets obtained. This new method of rubber sheet preparation was introduced into Amazonian rainforest rubber tapper communities, which are actually producing in large scale. The physical-mechanical properties were similar among a large sheets made by different rubber tapper communities using this new method.

Acids↗
PubMed2005

Development of a long-acting therapeutic system: Part I: A method to produce silicon rubbers with well-defined microstructures.

Based on the free-volume theory of diffusion in rubbers it is shown that the diffusion coefficient D of a permeating drug can be written as the product of two probabilities D approximately w(1)w(2). The polymer chains in a rubber are subject to thermal vibrations. Hence collisions between vibrating polymer segments and permeating drug molecules can occur. w(1) describes the probability that by such a collision a drug molecule experiences an energy exchange which is large enough to overcome its interactions with its neighborhood. w(2) describes the probability that a permeating drug molecule will find in its immediate neighborhood a free volume being equal or larger than its own volume. Diffusion takes place if the drug molecule experiences a sufficiently large exchange of momentum and finds at the same time a sufficiently large free volume. As both events are independent their overall probability is given by the product of the two probabilities. For a given rubber and a given species of drug molecules in a first approximation w(1) can be considered as constant. This means the diffusion coefficient is mainly determined by w(2). This probability, however, is strongly determined by the microstructure of the rubber. In this study a procedure is developed allowing for a straightforward synthesis of silicone rubbers with defined network density.

Delayed-Action Preparations↗
PubMed2004

Structural identification of extractables from rubber closures used for pre-filled semisolid drug applicator by chromatography, mass spectrometry, and organic synthesis.

Extractables or leachables from rubber closures used for drug products can potentially be detrimental since some of these rubber extractables are known to be toxic and pyrogenic. In addition, these extractables could interfere with analysis or even affect the stability profile of the active ingredients. For these reasons, it became necessary to identify structures of the possible extractables or leachables from rubber closures so that their potential impact on the drug products that are in direct contact with rubber closures could be evaluated. In this report, five species, 4-(1,1-dimethyl-propyl)-phenol (1), sulfur (2), 2,6-di-tert-butyl-[1,4] benzoquinone (3), furan-2-yl-(5-hydroxymethyl-furan-2-yl)-methanol (4), and 2-bromo-4-(1,1-dimethyl-propyl)-phenol (5), were found to be possible extractables from the rubber closures which were used in a selected pre-filled semisolid drug applicator. A strategy combining HPLC, GC, mass spectrometry, and organic synthesis was utilized.

Benzoquinones↗
PubMed2006

Crumb rubber filtration: a potential technology for ballast water treatment.

The removal of turbidity, particles, phytoplankton and zooplankton in water by crumb rubber filtration was investigated. A substantial reduction was achieved. Of the three variables, filter depth, media size and filtration rate, media size had the most significant influence. Smaller media size favored higher removal efficiency of all targeted matter. There was no apparent relationship between removal efficiency and filter depth. Higher filtration rate resulted in lower removal efficiency and higher head loss. Compared with conventional granular media filters, crumb rubber filters required less backwash, and developed lower head loss. Consequently crumb rubber filters could be run for a longer time or allow a higher filtration rate. The results also indicate that the crumb rubber filtration alone did not achieve the target removal of invasive species. However, crumb rubber filtration could potentially be used as a primary treatment technology to enhance the efficiency of a secondary treatment process (e.g., disinfection).

Animals↗
PubMed2004

Use of rubber and bentonite added fly ash as a liner material.

In many countries regulations require all hazardous waste disposal facilities to be lined with suitable impermeable barriers to protect against contamination. In this study, a series of laboratory tests on rubber and bentonite added fly ash were conducted. The aim of the tests was to evaluate the feasibility of utilizing fly ash, rubber and bentonite as a low hydraulic conductivity liner material. Type C fly ash was obtained from Soma thermal power plant in Turkey; rubber in pulverized form was waste from the retreading industry. To investigate the properties of rubber and bentonite added fly ash, hydraulic conductivity, leachate analysis, unconfined compression, split tensile strength, one-dimensional consolidation, swell and freeze/thaw cycle tests were performed. The overall evaluation of results have revealed that rubber and bentonite added fly ash showed good promise and a candidate for construction of a liner.

Bentonite↗
PubMed2004

Properties of concrete containing scrap-tire rubber--an overview.

Solid waste management is one of the major environmental concerns in the United States. Over 5 billion tons of non-hazardous solid waste materials are generated in USA each year. Of these, more than 270 million scrap-tires (approximately 3.6 million tons) are generated each year. In addition to this, about 300 million scrap-tires have been stockpiled. Several studies have been carried out to reuse scrap-tires in a variety of rubber and plastic products, incineration for production of electricity, or as fuel for cement kilns, as well as in asphalt concrete. Studies show that workable rubberized concrete mixtures can be made with scrap-tire rubber. This paper presents an overview of some of the research published regarding the use of scrap-tires in portland cement concrete. The benefits of using magnesium oxychloride cement as a binder for rubberized concrete mixtures are also presented. The paper details the likely uses of rubberized concrete.

Conservation of Natural Resources↗
PubMed2000

Acceptability evaluation of a natural rubber latex, a polyurethane, and a new non-latex condom.

After more than a century of reliance on latex condoms, male condoms fabricated from new materials are finally becoming commercially available to consumers. This study was an open label acceptability study that compared three lubricated condom products during vaginal intercourse: a natural rubber latex condom, a polyurethane condom, and a new non-latex (styrene ethylene butylene styrene, SEBS) condom. Fifty-four couples who were using condoms for birth control were enrolled in this three-way crossover study. Each couple tested three condoms of each type in a randomized sequence. Couples reported condom performance after each use and rated condom acceptability after use of three condoms of each type. At the completion of the study, participants selected their preferred condom type for overall acceptability, sensitivity, ease of use, appearance, and comfort. All three condom types had low clinical breakage and slippage rates (</= 3.3%) although the polyurethane condom did not perform as well in other measures of performance including unrolling, discomfort, stretching, bunching, and sliding along the penis during intercourse. None of the condom types were statistically preferred overall [males: natural rubber latex 37%, polyurethane 24%, new non-latex (SEBS) 37%, no preference 2%; females: natural rubber latex 33%, polyurethane 27%, new non-latex 37%, no preference 2%]. A statistically higher proportion of couples preferred both the natural rubber latex condom and the new non-latex condom above the polyurethane condom for ease of unrolling, and the natural rubber latex condom above the other condom types for perceived safety. Approximately two-thirds of both male and female participants preferred one of the two condoms made of synthetic materials suggesting that consumers will appreciate the availability of these products.

Adolescent↗
PubMed1991

Rubber-specific IgE in children with spina bifida.

We attempted to determine the prevalence and clinical significance of rubber-specific IgE in a prospective case control study of 32 preoperative children with spina bifida, compared with 45 outpatient controls and 35 age-matched preoperative controls without spina bifida. A latex-specific radioallergosorbent test was positive in 11 of the 32 spina bifida patients (34%), compared with 1 (2%) and 4 (11%) of the respective controls (p less than 0.05). Within the spina bifida group 5 of 11 antibody-positive patients had a history of rubber-associated, intraoperative or otherwise idiopathic allergic episodes and 1 of 21 antibody-negative patients gave such a history (p = 0.012). Children with spina bifida have a significantly greater likelihood than controls of having IgE specific for rubber antigens. In addition, the presence of rubber-specific IgE is associated with a higher frequency of rubber-associated, intraoperative or idiopathic allergic reactions.

Adolescent↗
PubMed1993

Binding of Escherichia coli to Penrose rubber drains--an in vitro study.

Ten different isolates of Escherichia coli were used to compare bacterial attachment to Penrose rubber drains at different temperatures and to investigate a possible relation with cell surface hydrophobicity and charges, as well as the capacity of autoaggregation. Penrose rubber drain pieces of 1 cm2 were incubated with 4.8 x 10(6) E. coli cells for 1 h at 22, 37 and 42 degrees C, respectively. After rinsing with phosphate buffered saline (PBS), the number of adhering bacteria on the drain pieces was calculated by measuring cellular ATP (adenosine triphosphate) bioluminescence. Bacterial cell surface properties at different temperatures were determined by two-phase partitioning and autoaggregation was determined by arbitrary scoring under the dissecting microscope. For most strains of E. coli, the number of adherence to Penrose rubber drain was higher at 22 degrees C than at 37 degrees C and 42 degrees C. Bacterial cell-surface properties and autoaggregation capacity were influenced by the growth temperature, but without correlation to bacterial ability to attach to rubber drains. Thus, the present study demonstrates that attachment of E. coli to Penrose rubber drains was significantly influenced by temperature, but bacterial cell-surface hydrophobicity and charge as well as autoaggregation capacity had no influence on bacterial attachment ability.

Bacterial Adhesion↗