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Growth of microorganisms on rubbers and plastics. Medical aspects of microbiological corrosion and the role of quality control.

The cause of nosocomial infections and their possible solutions, according to the chemical compounds of rubber and plastic equipments are shortly summarized. Compounds of rubbers and plastics act as culture medium for bacteria and fungi being causative agents in nosocomial infections and because of their long-term persistence they can be source of such infections. This problem needs cooperation between experts and specialists from different scientific fields working in both industry and medicine. Only "united forces" can make steps in order to find solutions to these emerging questions and problems.

Candida↗

Blue rubber bleb nevus syndrome: a cause of gastrointestinal hemorrhage.

Blue rubber bleb nevus syndrome is an uncommon disorder manifested by cutaneous and gastrointestinal hemangiomas and gastrointestinal hemorrhage causing anemia. We describe a young man who presented with hematemesis and melena and had multiple bluish rubber bleb-like hemangiomas over the body and in the stomach, jejunum and colon. The patient was treated with iron supplements for anemia; he is doing well 6 months later.

Adolescent↗

The use of solid soft silicone rubber exoplants in retinal detachment surgery.

A method of retinal detachment surgery utilizing soft solid silicone rubber exoplants is described along with its use in typical cases. Solid silicone rubber, long used as a scleral implant, is a well-tolerated exoplant scleral buckling material which has been found to provide excellent long-term results. The surgical procedure described is relatively short in duration and has a minimum of operative and postoperative complications.

Humans↗

Effect of follow-up time on risk estimates: a longitudinal examination of the relative risks of leukemia and multiple myeloma in a rubber hydrochloride cohort.

BACKGROUND: Choice of follow-up time for an occupational cohort can influence risk estimates. We examined the effects of follow-up time on relative risk estimates for leukemia and multiple myeloma in a cohort of 1,845 rubber hydrochloride workers. MATERIALS AND METHODS: We generated standardized mortality ratios (SMRs) for yearly follow-ups, beginning each study in 1940 and increasing study end dates from 1950 through 1996. We used Cox proportional hazards modeling to explore the effects of follow-up time on the exposure-response relationship. RESULTS: The SMR for leukemia rose to 13.55 in 1961 and fell nearly monotonically to 2.47 by 1996. Cox modeling suggested interaction between cumulative exposure and time since exposure. A longer time to peak risk was seen for multiple myeloma. CONCLUSIONS: Because summary risk estimates change with follow-up time, exposure limits set using these estimates may not adequately protect workers. Consideration of appropriate follow-up time and use of more complex temporal models are critical to the risk assessment process.

Benzene↗

Screening for occupational health hazards in the rubber industry. Part I.

Multiphasic health testing (MHT) is often offered to populations of workers usually with the objective of identifying individuals who may be ill. Results are typically not analyzed in relation to estimates of workplace exposure. We describe the results of combining MHT with industrial hygiene assessment of workplace exposures as a method of identifying possible health hazards rather than merely potentially ill individuals. MHT was offered to all production and maintenance workers employed at a tire manufacturing plant. Of 954, 744 participated. We measured worker exposure to respirable particulates, solvent vapor, and noise. We computed the frequency of positive screens among workers classified by exposure and compared these frequencies with expected values adjusted for confounding variables including age, sex, race, and smoking and drinking habits. Workers exposed to higher concentrations of respirable particulates exhibited signs of respiratory and gastrointestinal morbidity. Workers exposed to emissions from heated, uncured rubber undergoing plastic deformation reported chest tightness on return to work. We conclude that combining MHT with assessment of workplace exposure is a valid method for identifying possible occupational health hazards.

Environmental Exposure↗

Screening for occupational health hazards in the rubber industry. Part II: health hazards in the curing department.

Multiphasic health testing was provided to 744 rubber workers at a tire manufacturing plant. Sixty-two white males from this population had worked longest in the curing department. Personal exposure to respirable particulates was measured for curing press operators. Outcome on screening tests for curing workers was compared with that of 280 white males at this same plant who had never worked in departments known to include jobs where they could have been exposed to respiratory health hazards. Employment in the curing department is associated with shortness of breath, chest tightness, wheeze, loss of FEV-1 and FVC, decline of FEV-1/FVC, and tingling and numbness in the extremities. These associations are stronger with increased duration of employment in the curing department. This paper further demonstrates the potential for using multiphasic health testing combined with measurements of workplace exposure for identifying occupational health hazards.

Adult↗

Mortality and cancer morbidity among workers in the rubber tire industry.

A retrospective follow-up study was conducted to evaluate mortality and cancer incidence between 1954 and 1976 among 1,792 white male production workers employed for at least 2 years at a tire manufacturing plant. There were no marked excesses in overall or site-specific cancer deaths or incident cases. Compared to U.S. white males, men employed for at least 10 years experienced small increases in deaths from cancers of the large intestine, pancreas, and lung. Results obtained by comparing observed incident cancer cases to the numbers expected based on age- and calendar time-specific incidence rates of Connecticut males also suggested excesses of these three malignancies. These findings were based on small numbers and therefore do not necessarily indicate causal associations between cancer excesses and employment in the rubber tire industry. However, because the workers studied comprised a relatively young population that may not have experienced the full impact of carcinogenic occupational exposures, further follow-up is warranted.

Adult↗

Chemical and mechanical trauma to the skin in a rubber fabricating facility.

Frequent hand-washing using organic solvent caused chronic irritation on the hands of workers in a rubber fabricating facility. Mechanical traction applied to the skin of the thumbs and fingers and scrubbing of chemically traumatized skin during washing appeared to contribute to fissuring and nail bed separation.

Hand Dermatoses↗

A mortality study of employees at a synthetic rubber manufacturing plant.

A mortality follow-up study was conducted of workers employed at a synthetic rubber manufacturing plant in Baton Rouge, Louisiana. Interest in the potential health effects of exposure to methyl chloride, one of the substances used in the manufacturing process, provided the impetus for this study. The study cohort consisted of 852 male process workers who had worked at least 1 month during the period from startup of operations in 1943 through December 31, 1978. Mortality from all causes was lower than expected when compared with the U.S. male population. No excess mortality from any specific cause of death was found in the study population after analysis by level and duration of exposure.

Cardiovascular Diseases↗

Lung cancer case-control study in a rubber manufacturing plant.

This report presents the findings of a case-control study of lung cancer among workers at a rubber manufacturing plant. Detailed work histories of 40 lung cancer deaths, which occurred during 1977 and 1978, were compared with those of 146 controls who were individually matched to cases on age, sex, and race; 66 of the controls were also matched on year of first hire. Elevated odds ratios were noted for different durations of employment in four work areas: Reclaim Operation, Chemicals, Special Products Manufacture, and Curing Preparation. A clear trend of increasing odds ratios with increasing durations of exposure was observed for the first three of these work areas. Several chemicals used in these processes are known respiratory system hazards. The results of this study suggest an association between lung cancer mortality risk and employment in Reclaim Operation, Chemicals, and Special Products Manufacture. A moderate excess risk was observed in these areas among both smokers and nonsmokers, although the risk was greater among the smokers.

Adult↗

Benzene exposure assessment in rubber hydrochloride workers: a critical evaluation of previous estimates.

Many risk assessments for leukemia associated with benzene exposure have been based on the mortality experience of the rubber hydrochloride worker cohort. Although there have been several different historical exposure assessments proposed for this cohort, Paustenbach et al. [1992, J Tox Environ Health], recently published a new historical characterization of benzene exposures based on data previously developed by Rinsky et al. [1981, Am J Ind Med] and further modified by Crump and Allen [1984: OSHA]. Adjustments by Paustenbach et al. in the Rinsky et al. data result in retrospective benzene exposure estimates far greater than those previously reported, by an order of magnitude in many cases. Judgments made on the significance of dermal contact and interpretation of historical measurement data led Paustenbach et al. to arrive at exposure estimates for this cohort that are in conflict with what is known about the adverse effects of benzene exposure. More reasonable estimates for dermal absorption are included in this report that do not substantially affect total estimates of benzene exposure for the cohort. The exposure estimates originally presented in the Rinsky et al. article appear in concordance with data not previously reported in any analyses.

Air Pollutants, Occupational↗

Injuries caused by rubber bullets: a report on 90 patients.

The injuries in 90 patients caused by rubber bullets are described. There was 1 death and 17 people in the series had permanent disabilities or deformities. In 41 patients the injuries necessitated admission to hospital. One fatality outside this series is known. Injuries to the head and neck were frequent and severe.

Abdominal Injuries↗

Systematic review of randomized trials comparing rubber band ligation with excisional haemorrhoidectomy.

BACKGROUND AND METHOD: This review compares the two most popular treatments for haemorrhoids, namely rubber band ligation (RBL) and excisional haemorrhoidectomy. Randomized trials were identified from the major electronic databases. Symptom control, retreatment, postoperative pain, complications, time off work and patient satisfaction were assessed. Relative risk (RR) and weighted mean difference with 95 per cent confidence interval (c.i.) were estimated using a random-effects model for dichotomous and continuous outcomes respectively. RESULTS: Three trials met the inclusion criteria and all were of poor methodological quality. Complete remission of haemorrhoidal symptoms was better after haemorrhoidectomy (RR 1.68 (95 per cent c.i 1.00 to 2.83)). There was significant heterogeneity between the studies (I(2) = 90.5 per cent; P < 0.001). Fewer patients required retreatment after haemorrhoidectomy (RR 0.20 (95 per cent c.i 0.09 to 0.40)), but anal stenosis, postoperative haemorrhage and incontinence to flatus were more common with this operation. CONCLUSIONS: Haemorrhoidectomy produced better long-term symptom control in patients with grade III haemorrhoids, but was associated with more postoperative complications than RBL.

Hemorrhoids↗

Mutagenic evaluations of four rubber accelerators in a battery of in vitro mutagenic assays.

The mutagenic/carcinogenic potential of four commercial accelerators were evaluated using a battery of in vitro assays. All of these compounds were mutagenic in one or more assays. Positive responses were noted in the Escherichia coli pol A+/pol A- DNA repair, mouse lymphoma L5178Y TK+/- forward mutation, BALB/3T3 cell transformation, and CHO cell chromosome aberration assays. In contrast to previous studies of accelerators, no mutagenic response was observed in the E coli WP2 uvrA- assay or in any of the Salmonella typhimurium strains tested. These studies have indicated that rubber accelerators should be regarded as potential human health hazards and that further in vitro and in vivo studies are needed to assess the potential genetic hazards of this large class of chemicals.

Benzothiazoles↗

Biaxial flex-fatigue and viral penetration of natural rubber latex gloves before and after artificial aging.

Barrier integrity of unaged and oven-aged (at 70 degrees C) natural rubber latex examination gloves was assessed with a biaxial flex-fatigue method where failure was detected electronically, and by live viral penetration testing performed according to a modified version of ASTM F1671-97a. When no change in barrier properties was detected during flex testing, no virus passage was found after viral challenge. Conversely, when a change in the barrier properties was indicated by the electrical signal, virus passage was found in 74% of the specimens. Flex-fatigue results indicated that unaged test specimens from powdered (PD) and powder-free (PF) nonchlorinated gloves had significantly longer fatigue lives than powder-free chlorinated (CL) gloves from the same manufacturer. Biaxial flexing of oven-aged glove specimens showed a marginal increase in fatigue life for the PF gloves, but no increase for the PD gloves. The fatigue life of the CL gloves was observed to increase significantly after oven aging. However, this appears to be due to a design feature of the test apparatus, wherein peak volume displacement of the worked specimen is held constant. An aging-induced change in the viscoelastic properties of the CL gloves-permanent deformation of the specimens early in the fatigue test-relieves the stress magnitude applied as the test progresses. Thus, permanent deformation acts as a confounding factor in measuring durability of latex gloves by fixed displacement flex-fatigue.

Bacteriophage phi X 174↗

Comparative studies by cell culture and in vivo implantation test on the toxicity of natural rubber latex materials.

Colony assay using V79 cells, the agar diffusion assay with L929 cells, and the 7-day rabbit muscle implantation test were employed to evaluate the cytotoxicity and tissue toxicity of natural rubber latex (NRL) materials. The in vivo implantation test showed that, among 13 histological parameters, thickness of inflammatory layer was the most useful index to evaluate tissue responses quantitatively. A comparison of the in vivo and in vitro parameters revealed the following correlations between the thickness of the inflammatory layer and cytotoxicity indices: Colony assay of the extracts, IC50: r = 0.80; Agar diffusion assay, Zone index: r = 0.73; Lysis index: r = 0.61. From these results, it appears that the colony assay provides a more reliable prediction of the tissue response than the agar diffusion assay.

Animals↗

In vitro induction of polyploidy and chromatid exchanges by culture medium extracts of natural rubbers compounded with 2-mercaptobenzothiazole as a positive control candidate for genotoxicity tests.

We tested extracts of custom-made natural rubber samples for cytotoxicity using V79 cells and for chromosome aberration (CA) induction using CHL cells in compliance with the Japanese guidelines for basic biological tests of medical materials and devices. The samples were formulated with a high level of 2-mercaptobenzothiazole (MBT) (A); a low level of MBT (B); or zinc dibutyldithiocarbamate (ZDBC) (C). In the CA test, MBT induced mainly polyploidy, including endoreduplication, and ZDBC induced structural CAs. In the cytotoxicity test, culture medium extracts of A, B, and C suppressed colony formation to 50% of the control value at 53.1%, 94.3%, and >100%, respectively. Culture medium extracts of sample A induced polyploidy and structural CAs in the absence of an exogenous metabolic activation system (S9 mix), but at lower concentrations in its presence, indicating the existence of other leachable promutagens. The extracts of sample B induced structural CAs at the highest concentration and only with S9 mix. Sample C was negative. The facts suggest that sample A may be a candidate for a positive control for genotoxicity tests. The high frequency of polyploidy induced by sample A was not predicted by MBT, suggesting the usefulness of the test for safety evaluation of medical devices. Numerical CAs induced by MBT and sample A are discussed.

Animals↗

Cryo-sectioning and chemical-fixing ultramicrotomy techniques for imaging rubber latex particle morphology.

Two methods adapted from biological microscopy are described for a new application in imaging the morphology of rubbery latex particles. In the first method, a drop of latex is frozen in liquid nitrogen, sectioned with a diamond knife and vapour-stained with osmium tetroxide, then viewed by transmission electron microscopy. When applied to latexes made by emulsion polymerization of methyl methacrylate in a natural rubber latex seed, inclusions are clearly visible. A chemical fixation method is then described for imaging the morphology of such rubbery latex particles. Glutaraldehyde is added to the latex, followed by osmium tetroxide. The sample is then dehydrated in ethanol, epoxy resin added, and the sample cured, ultramicrotomed, and imaged with transmission electron microscopy. An inclusion morphology is again clearly seen.

Cryoelectron Microscopy↗