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Clinical field testing of vulcanized Jaipur rubber feet for trans-tibial amputees in low-income countries.

The purpose of this study was to check out the performance and durability of vulcanized Jaipur rubber feet in tropical areas of the developing world. Forty-one MUKTI and 40 NISHA feet were followed for 16 (8 - 17) months. The user compliance was high and nearly all were satisfied. Failure of the prosthetic foot with the need for exchange at the end of the study amounted to 27% (22/81), which is equivalent to a mixed series of rubber feet previously reported (Jensen et al. 2006b). Failures were mostly related to skin fracture and gliding between sponge rubber layers of the heel block.

Adult↗

The effect of rubber closures on the haze state of ceftriaxone sodium for injection.

The migration of volatile components into the headspace of glass vials from rubber closures is a potential source of haze formation in reconstituted solutions of powders for parenteral administration. In this paper, a headspace method was used to extract volatile substances from different types of rubber closures used in ceftriaxone sodium for injection whose clarity were poor. The extracts obtained were analyzed by gas chromatography (GC)-mass spectrometry (MS). An antioxidant in rubber closures, butylated hydroxytoluene (BHT), was found to affect the haze state of ceftriaxone sodium for injection.

Adsorption↗

Extraction of copper and zinc from rubber and silicone stoppers.

Drugs and other chemicals are often administered in the drinking water of laboratory animals, and bottles for this purpose usually have rubber stoppers. We studied the ability of solutions of several drugs to extract copper and zinc from rubber and silicone stoppers. Water and isoniazid extracted little copper or zinc from rubber stoppers, whereas EDTA, ethambutol, tetracycline, and chlorpromazine generally extracted considerable quantities of copper and zinc from these stoppers. Neither water nor solutions of the above drugs extracted copper or zinc from silicone stoppers. We routinely use silicone stoppers on water bottles when conducting laboratory studies requiring administration of drugs, toxins, or nutrients in the drinking water.

Copper↗

Cancer mortality and solvent exposures in the rubber industry.

Some evidence suggests that solvent exposures to rubber industry workers may be associated with excess cancer mortality, but most studies of rubber workers lack information about specific chemical exposures. In one large rubber and tire-manufacturing plant, however, historical documents allowed a classification of jobs based on potential exposures to all solvents that were authorized for use in the plant. A case-control analysis of a 6678 member cohort compared the solvent exposure histories of a 20% age-stratified random sample of the cohort with those of cohort members who died during 1964-1973 from stomach cancer, respiratory system cancer, prostate cancer, lymphosarcoma, or lymphatic leukemia. Of these cancers, only lymphosarcoma and lymphatic leukemia showed significant positive associations with any of the potential solvent exposures. Lymphatic leukemia was especially strongly related to carbon tetrachloride (OR = 15.3, p less than .0001) and carbon disulfide (OR = 8.9, p = .0003). Lymphosarcoma showed similar, but weaker, associations with these two solvents. Benzene, a suspected carcinogen, was not significantly associated with any of the cancers.

Adult↗

The energy value for and nutritive value of para-rubber seed for rats.

The digestible (DE) and metabolizable energy (ME) of full-fat and defatted rubber seed meals (FRS and DRS) were determined with weanling albino rats fed diets in which the meals replaced either 20 or 40% glucose monohydrate in the reference diet. The nutritive value of both FRS and DRS included at 10, 20 and 30% of the diet as substitutes for groundnut meal and yellow maize was studied with 56, 28-day-old albino rats of the Wistar strain. The trial lasted 28 days. Nutrient digestion and nitrogen retention were studied at the end of the second week on test. The DE and ME for FRS were on average 24.7 +/- 1.30 and 21.7 +/- 0.80 hy/g dry matter and those for DRS were 15.3 +/- 0.97 and 13.8 +/- 0.46 hy/g dry matter. Incorporation of rubber seed meals at increasing levels in the diet significantly depressed gains and worsened feed/gain ratio (P < 0.01), the diet containing 30% FRS or 20 and 30% DRS being significantly inferior to the control and the diet with 10% FRS or DRS. Significantly (P < 0.01) superior gains but not feed intake and efficiency were obtained for FRS compared to DRS. Percent intake -N retained also decreased with increasing rubber seed levels in the diet. Except for the significantly (P < 0.05) higher crude fibre digestibility of the control diet compared with those containing 20 or 30% FRS or DRS, the digestibilities of other nutrients were not significantly different.

Animal Feed↗

Exposure to nitrosamines, carbon black, asbestos, and talc and mortality from stomach, lung, and laryngeal cancer in a cohort of rubber workers.

There is sufficient evidence for an excess occurrence of stomach and lung cancer among rubber workers. However, evidence for causal associations with specific exposures is still limited. A cohort of 8,933 male German rubber workers was followed for mortality from January 1, 1981 through December 31, 1991. Work histories were reconstructed using routinely documented cost center codes. For each cost center code, calendar time-and plant-specific levels of exposure to nitrosamines, asbestos, talc (low, medium (m), and high (h)), and carbon black (two levels) were estimated by industrial hygienists. Rate ratios (RR) and 95% confidence intervals (CI) were calculated using Cox proportional hazards models, with the lowest exposure level used as the reference category. Exposure was lagged 10 years to account for latency. Exposure-response relations between exposure to asbestos and lung cancer mortality (RRm = 1.3, 95% CI: 0.9, 1.9; RRh = 2.0, 95% CI: 0.9, 4.1) and between exposure to dust (talc and asbestos combined) and stomach cancer mortality (RRm = 1.8, 95% CI: 0.9, 3.8; RRh = 2.7, 95% CI: 1.0, 7.1) were observed. Exposure to nitrosamines was not associated with mortality from stomach or lung cancer. These results suggest that the increased mortality from lung and stomach cancer among rubber workers is associated with exposure to asbestos and dust, respectively.

Aged↗

Empirical modelling of chemical exposure in the rubber-manufacturing industry.

As part of a study of working conditions chemical exposure was assessed in 10 rubber-manufacturing plants in The Netherlands. Personal exposures to airborne particulates, rubber fumes and solvents, and also dermal contamination, were measured. To identify factors affecting exposure the personal exposure levels and information on tasks performed, ventilation characteristics and production variables were used in multiple linear regression models. The exposure was generally very variable. The specific circumstances in each department of each plant determined the actual levels of exposure to a large extent. The factors affecting exposure turned out to be different for each of the types of exposure considered. The model for exposure to airborne particulates explained 40% of the total variability and incorporating the actual time spent on a task only slightly improved the model (R2 = 0.42). The handling of chemicals in powder form was the main factor affecting exposure, forced ventilation having a negligible effect. The model for exposure to curing fumes (measured as the cyclohexane-soluble fraction of the particulate matter) explained 50% of the variability. Both curing temperature and pressure determined the level of rubber fumes. Local exhaust ventilation showed a significant exposure reducing effect. The effect of curing different elastomers was not statistically significant. Dermal exposure to cyclohexane-soluble matter could only be explained to a limited extent (R2 = 0.22). Tasks with frequent contact with (warm) compound and maintenance tasks in the engineering services departments resulted in high dermal exposure. Tasks in which solvents were directly used explained 56% of the variation in solvent exposures. Exposure data, together with information on tasks, methods of work, ventilation and production throughout a branch of industry, can be used to derive empirical statistical models which occupational hygienists can apply to study factors affecting exposure. These determining factors are of crucial importance, whenever hazard control or epidemiological research is the ultimate goal.

Air Pollutants, Occupational↗

A database of exposures in the rubber manufacturing industry: design and quality control.

The concerted action EXASRUB was initiated to create a database management system for information on occupational hygiene measurements that could be used to develop exposure models in the European rubber manufacturing industry. Quality of coding was assessed by calculating percentages of agreement and Cohen's kappa statistics (kappa) for an intra- and inter-centre recoding of randomly selected subsets of the measurements. In a 6-month period, 59 609 measurements from 523 surveys in 333 factories from as early as 1956 to 2003 were coded. The database consists primarily of measurements of N-nitrosamines (36%), rubber dust (23%), solvents (14%) and rubber fumes (10%). Coding of epidemiologically relevant information was done consistently with inter-centre kappa between 0.86 and 1.00. For occupational hygiene information, values of kappa were estimated to be between 0.67 and 1.00. The proposed method resulted in a large quantity of exposure measurements with auxiliary information of varying completeness and quality. Analyses showed that coding of epidemiologically relevant information in such a multi-centre, multi-country study was coded consistently. Larger errors however, occurred in coding of occupational hygiene information. This was primarily caused by lack of information in the primary records of measurements, emphasizing the importance of having a universal system in place to collect and store measurement information by occupational hygienists for future use.

Chemical Industry↗

Interference with analysis of amphetamine in blood by N-ethylbenzenamine from rubber septums.

When blood stored in glass vials sealed with natural rubber septums was screened for amphetamine, a contaminant was seen. The contamination originated from the rubber septums and was identified by GC/MS as N-ethylbenzenamine. Like amphetamine, N-ethylbenzenamine was extracted from strongly alkaline solutions. N-Ethylbenzenamine and amphetamine chromatographed with the same retention time on a packed Apiezon/KOH column and on nonpolar capillary columns. Separation was achieved on a medium polar capillary column. Trifluoroacetyl derivatives of amphetamine and N-ethylbenzenamine had the same retention time on a packed SP-2250 column, but separated on nonpolar capillary columns. The amounts of N-ethylbenzenamine found were high enough to give rise to significant false positive results if N-ethylbenzenamine was erroneously read as amphetamine. N-Ethylbenzenamine is believed to be formed by thermal decomposition of the vulcanizing agent zinc ethylphenyldithiocarbamate used in rubber production.

Amphetamine↗

Dermal exposure, handwashing, and hand dermatitis in the rubber manufacturing industry.

Skin diseases, such as hand dermatitis, are thought to be a common problem in the rubber manufacturing industry, as workers are exposed to a wide range of chemicals with known irritant and sensitizing potential. We conducted a cross-sectional survey of a representative sample of rubber manufacturing workers (N = 202), selected from nine different rubber companies. Prevalence of hand dermatitis ("major" and "minor" dermatitis) and skin injuries was assessed on the basis of a diagnosis by a dermatologist. We investigated the possible relations between actual skin exposure, handwashing practices, and hand dermatitis. Prevalence of major hand dermatitis (7%) was comparable with that in the general population; however, minor signs of dermatitis were more common among the surveyed population (28%), as were traumata of the skin (17%). Dermal exposure to cyclohexane-soluble agents at work was related to the occurrence of major hand dermatitis, but not to the occurrence of minor hand dermatitis. Moderate and frequent handwashing especially with industrial surfactants containing scrubbing particles were found to be strongly associated with the occurrence of minor dermatitis [odds ratio = 4.27 (95% confidence interval = 0.90-20.27) and odds ratio = 6.38 (95% confidence interval = 1.33-30.17, respectively)].

Administration, Cutaneous↗

The occupational determinants of chronic disabling pulmonary disease in rubber workers.

Chronic respiratory disease is among the three leading causes of premature retirement due to work disability. The association of occupational exposure and smoking history as potential determinants of pulmonary disability retirement were examined. A cohort of 4302 male, hourly rubber workers actively employed at the Akron plant of a large rubber company on January 1, 1964 was identified and followed for ten years. During the period, 1964-1973, 73 workers terminated gainful employment with a pulmonary disability retirement. Work and smoking histories for these cases and two age-race-sex matched control groups were ascertained. Cases spent significantly greater durations of time employed in curing preparation, curing and finishing and inspection work areas. Each of these areas involves exposures to particulate material and/or solvents. Significant risk of developing a pulmonary disability was associated with smoking and exposure to dust and fumes, generally, and talc and carbon black more specifically. Smoking and occupational exposures were found to interact in their association with pulmonary disability retirement among these rubber workers.

Adult↗

Risks of brain tumors in rubber workers: a metaanalysis.

OBJECTIVE: To better understand whether rubber industry workers suffer increased risks of brain tumor, a concern that has persisted for over 40 years despite numerous well-conducted studies. METHODS: We performed a formal metaanalysis of brain tumor risk estimates reported in cohort studies of rubber and tire workers. Twenty unique cohorts were identified who met a priori inclusion criteria. Metaanalysis was performed using the general variance-based method; the variance of risk estimates was calculated for each study using a chi-squared method. Homogeneity was tested by means of the Q statistic. RESULTS: The metaanalysis determined an overall relative risk of 0.90 (95% CI = 0.79-1.02). CONCLUSIONS: The analytical results are consistent with a conclusion that risks of brain tumor are not increased as a result of occupational exposures in the rubber and tire industry.

Brain Neoplasms↗

Occupational peri-ocular contact dermatitis due to sensitization against black rubber components of a microscope.

A 24-year-old female working in the Department of Pathology of a University Hospital developed an acute peri-ocular eczema clearly being related to her daily work at the microscope. Patch testing revealed delayed type hypersensitivity against the black rubber mix, N-isopropyl-N'-phenyl paraphenylenediamine, N-cyclohexyl-N'-phenyl paraphenylenediamine and the rubber ring situated on the ocular of the respective microscope. This is the first report, to our knowledge, on peri-orbital allergic contact eczema because of sensitization with rubber components of a microscope.

Adult↗

A study of natural rubber latex allergens in gloves used by healthcare workers in Singapore.

BACKGROUND: Allergy to natural rubber latex (NRL) proteins is a well-recognized health problem among subjects using protective gloves and products made of NRL. There is currently no information on NRL allergen levels in gloves used in Singapore. OBJECTIVES: This study aims to quantify the amount of specific allergens (Hev b 1, Hev b 3, Hev b 5 and Hev b 6.02) found in rubber gloves used in Singapore. It also aims to determine if these levels are above thresholds that may cause NRL allergy. It also compares the levels of these specific allergens in gloves used for different purposes, namely gloves used for examination purposes or for surgical procedures. METHODS: Forty-nine rubber gloves were obtained from major hospitals and healthcare departments in Singapore and were analysed for their NRL allergen levels. FITkit, based on the enzyme immunometric assay technique, was used to determine the specific allergen levels of Hev b 1, Hev b 3, Hev b 5 and Hev b 6.02 in the gloves. RESULTS: Examination gloves had higher NRL allergen content compared with surgical gloves, and powdered gloves had higher allergen content compared with nonpowdered gloves. Among the various allergens, Hev b 5 and Hev b 6.02 were present in larger quantities than Hev b 1 and Hev b 3. Only two of 19 (11%) surgical gloves had the sum of the four allergens (Hev b 1, Hev b 3, Hev b 5, Hev b 6.02) in excess of 1 microg g(-1), which is believed to be a clinically relevant threshold. Among the examination gloves, 25 of 30 (83%) exceeded this level. CONCLUSIONS: This study shows that NRL allergen levels are present in the majority of examination gloves used by healthcare workers in Singapore at levels high enough to cause NRL allergy among sensitized persons. The information can serve as evidence for a possible requirement for manufacturers to produce gloves with low NRL allergen levels and to state the allergen level in gloves in the product information.

Allergens↗

Abdominal rubber drain piece aggravates intra-abdominal sepsis in the rat.

Biomaterials in the peritoneal cavity disrupt the physiology of the host and may cause bacterial translocation. The current study was performed to determine whether biomaterials exacerbate intra-abdominal infections. Adult male rats were divided into four groups: group 1, celiotomy+intraperitoneal (i.p.) saline; group 2, celiotomy+i.p. Escherichia coli (3 x 10(8) cfu); group 3, i.p. rubber+i.p. saline; and group 4, i.p. rubber+i.p. E. coli (3 x 10(8) cfu). Twelve h after the challenge, enteric bacterial translocation, bacterial population levels in the cecum and serum levels of IL-6 and TNF were measured. Bacterial translocation to mesenteric lymph nodes and the liver was observed in animals from groups 2 and 3, but significantly increased in group 4 with a concomitant elevation of serum levels of TNF and IL-6, as compared with group 1. Histological examination revealed a more pronounced inflammatory reaction in the peritoneum and distal ileum in group 4 than in groups 2 and 3. These results suggest that the presence of rubbers in the peritoneal cavity aggravates intra-abdominal sepsis.

Abdomen↗

Rubber sump drainage of enterocutaneous fistulae.

Effective sump drainage of high enterocutaneous fistulae, together with alimentary rest and total parenteral nutrition, is now an integral part of the modern management of patients with this condition. The low tissue reactivity of the plastic and polymer materials currently used in most drainage tubes appears however, to be counterproductive to the establishment of a discrete fistula track and control of the fistula. A case is made for the use of red rubber sump drains for enterocutaneous fistulae. The greater tissue reactivity of rubber is reviewed and confirmed by animal experimentation. A method of rubber sump drainage of enterocutaneous fistulae developed during the management of 83 such fistulae is described.

Animals↗

Late infections of pacemaker units due to silicone rubber insulation boots.

Early in 1980, there was an increase at our hospital of late infections of pulse generator pockets not due to perforation. No source of contamination could be found; then, late in 1981, the infection rate decreased. The only change in procedure during this period was the introduction of silicone rubber boots around the pacemaker unit to prevent muscle pacing. The risk of late infection was 13.8%, when using a rubber boot, while otherwise it was only 2.6% (p less than 0.001). The infections were usually caused by ordinary skin bacteria. The authors believe that the infections were due to bacteria introduced inside the rubber boot, where they were practically out of reach of the ordinary defense mechanisms. The decrease in infection rate occurred after the introduction of silicone-coated pacemakers.

Bacterial Infections↗

Taxonomic characterization of two rubber degrading bacteria belonging to the species Gordonia polyisoprenivorans and analysis of hyper variable regions of 16S rDNA sequences.

Two cis-1,4-polyisoprene (isoprene rubber) degrading bacteria, strains VH2 and Y2K, were identified as strains of the species Gordonia polyisoprenivorans belonging to the Corynebacterineae, a suborder of the order Actinomycetales. Both showed characteristic growth and degradation of isoprene rubber as described previously for the type strain of G. polyisoprenivorans Kd2 (DSM 44302(T)). For strain VH2 the chemotaxonomic properties were investigated, and DNA-DNA hybridization experiments with the type strain revealed the affiliation to the species G. polyisoprenivorans. The comparison of the 16S rDNA sequences, and especially hyper variable regions of these, led to the classification of strain Y2K to the same species. At present, the species G. polyisoprenivorans comprises three different isolates which share the ability to degrade isoprene rubber potently but which were obtained from different geographic regions.

Actinomycetales↗