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Construction and intergeneric conjugative transfer of a pSG5-based cosmid vector from Escherichia coli to the polyisoprene rubber degrading strain Micromonospora aurantiaca W2b.

A non-rubber degrading mutant of the polyisoprene rubber degrading bacterium Micromonospora aurantiaca W2b lacking the capability to form halos on latex overlay agar plates was isolated after N-methyl-N-nitro-N-nitrosoguanidine mutagenesis. A 10.3-kb shuttle cosmid vector pGM446 was constructed from the Streptomyces cloning vectors pGM160 and pOJ446. This vector was transferred by conjugation from Escherichia coli to M. aurantiaca W2b. The frequency of formation of exconjugants with pGM446 was 3.6 x 10(-3). This vector could be useful for shotgun cloning of genes into the non-rubber degrading mutant L1 from M. aurantiaca W2b.

Butadienes↗

Pustular reactions to hexafluorosilicate in foam rubber.

A case is reported of a foam rubber carrier with pustular lesions on the arms, wrists, thighs and trunk. Scratch and patch testing with the foam rubber components was negative. Animal testing revealed sodium hexafluorosilicate (Na2SiF6), one of the ingredients of the foam rubber, to be a pustulogen on previously damaged skin.

Adult↗

Allergic contact dermatitis due to rubber chemicals in haemodialysis equipment.

6 of 80 haemodialysed patients developed a sub-acute eczematous dermatitis of the area surrounding the arteriovenous shunt in the forearm. Patch tests were positive to rubber chemicals: 6 patients reacted to the thiuram group, 4 of them also to carba compounds. Since the equipment contained only small pieces of rubber, the cause of the allergy remains obscure. It is possible that allergy was caused by short and intermittent contact of the skin with the rubber gloves used by the nursing personnel.

Adult↗

A method for identifying causative chemicals of allergic contact dermatitis using a combination of chemical analysis and patch testing in patients and animal groups: application to a case of rubber boot dermatitis.

A 63-year-old woman developed allergic contact dermatitis from rubber boots. Initial investigation, by patch testing in the patient and chemical analysis of the causative rubber boots, revealed that mercaptobenzothiazole (MBT) and dibenzothiazyl disulfide (MBTS) were the causative chemicals. Subsequent investigations were performed by patch testing in animal groups. An extract of the causative rubber boots, MBT and MBTS were used for sensitization of guinea pigs by the guinea pig maximization test (GPMT). 3 animal groups, A (with the boot extract), B (with MBT) and C (with MBTS) were successfully prepared. The boot extract was fractionated by column chromatography and thin-layer chromatography (TLC). Each fraction was subjected to patch testing in the animal groups. Positive reactions in all groups would show that the active fractions contained MBT-type compounds, whereas a positive reaction in group A but negative ones in group B and C would show that the active fractions did not contain any MBT-type compounds. Each fraction was then analyzed by gas chromatography (GC), GC-mass spectrometry (GC-MS), direct inlet-MS (DI-MS) and high-performance liquid chromatography (HPLC). By this investigation, we found not only known allergens (MBT, MBTS), but also unknown allergens: S-substituted MBT-type compounds and styrenated phenol (SP). Thus, SP was shown to be a candidate as a human sensitizer even though the patient did not react to it.

Allergens↗

Reduction of E. coli adherence to rubber slices treated with phospholipids.

The present study aimed at modifying the surface of biliary drain material to reduce bacterial adherence. The adherence of cells of seven E. coli strains to rubber slices treated with phosphatidylcholin (PC) or phosphatidylinositol (PI) and the adherence of cells of E. coli strain NG7C to PC- or PI-treated rubber slices implanted in the common bile duct in rats were studied in vitro. The rubber slices were incubated with 1 x 10(7) cfu radiolabeled E. coli cells/ml at 37 degrees C for 60 min and then drained and washed thrice in 2 ml PBS, and adherent E. coli cells were quantified by radioactivity counting. The results show that both PC and PI absorbed on the surface of slices reduced the adherence of E. coli cells in at least two ways, i.e. by changing surface properties in vitro and by reducing deposition of host-derived molecules on phospholipid-treated surfaces in vivo. The results may be of use for modification of the biomaterial surface in the clinical situation.

Animals↗

Contact dermatitis from penetration of rubber gloves by acrylic monomer.

An orthopaedic surgeon developed dermatitis from acrylic materials. The acrylic monomer was found to penetrate surgical rubber gloves readily. Cases of "rubber glove dermatitis" with negative patch tests may have a similar explanation. Laboratory tests suggest that monomer does not damage rubber sufficiently to allow bacteria to penetrate gloves, but it remains possible that this would happen under theatre conditions.

Acrylic Resins↗

An updated study of mortality among North American synthetic rubber industry workers.

AIM: This study evaluated the mortality experience of workers from the styrene-butadiene industry. METHODS: The authors added seven years of follow up to a previous investigation of mortality among 17 924 men employed in the North American synthetic rubber industry. Analyses used the standardised mortality ratios (SMRs) to compare styrene-butadiene rubber workers' cause specific mortality (1943-98) with those of the United States and the Ontario general populations. RESULTS: Overall, the observed/expected numbers of deaths were 6237/7242 for all causes (SMR = 86, 95% CI 84 to 88) and 1608/1741 for all cancers combined (SMR = 92, 95% CI 88 to 97), 71/61 for leukaemia, 53/53 for non-Hodgkin's lymphoma, and 26/27 for multiple myeloma. The 16% leukaemia increase was concentrated in hourly paid subjects with 20-29 years since hire and 10 or more years of employment in the industry (19/7.4, SMR = 258, 95% CI 156 to 403) and in subjects employed in polymerisation (18/8.8, SMR = 204, 95% CI 121 to 322), maintenance labour (15/7.4, SMR = 326, 95% CI 178 to 456), and laboratory operations (14/4.3, SMR = 326, 95% CI 178-546). CONCLUSION: The study found that some subgroups of synthetic rubber workers had an excess of mortality from leukaemia that was not limited to a particular form of leukaemia. Uncertainty remains about the specific agent(s) that might be responsible for the observed excesses and about the role of unidentified confounding factors. The study did not find any clear relation between employment in the industry and other forms of lymphohaematopoietic cancer. Some subgroups of subjects had more than expected deaths from colorectal and prostate cancers. These increases did not appear to be related to occupational exposure in the industry.

Aged↗

Cancer mortality in the British rubber industry.

Although it is over 30 years since an excess of bladder cancer was first identified in British rubber workers, the fear has persisted that this hazard could still be affecting men working in the industry today. Furthermore, suspicions have also arisen that other and hitherto unsuspected excesses of cancer might be occurring. For these reasons 33 815 men, who first started work in the industry between 1 January 1946 and 31 December 1960, have been followed up to 31 December 1975 to ascertain the number of deaths attributable to malignant disease and to compare these with the expected number calculated from the published mortality rates applicable to the male population of England and Wales and Scotland. The findings confirm the absence of any excess mortality from bladder cancer among men entering the industry after 1 January 1951 (the presumed bladder carcinogens were withdrawn from production processes in July 1949), but they confirm also a statistically significant excess of both lung and stomach cancer mortality. A small excess of oesophageal cancer was also observed in both the tyre and general rubber goods manufacturing sectors. American reports of an excess of leukaemia among rubber workers receive only limited support from the present study, where a small numerical excess of deaths from leukaemia is not statistically significant. A special feature of the study is the adoption of an analytical method that permits taking into account the long latent period of induction of occupational cancer.

England↗

Mortality from cancer and other causes of death among synthetic rubber workers.

OBJECTIVES: This study evaluated the mortality experience of workers from the styrene-butadiene rubber industry. Concerns about a possible association of 1,3-butadiene and styrene with lymphohaematopoietic, gastrointestinal, and lung cancers prompted the investigation. METHODS: A retrospective follow up study was conducted of 15,649 men employed for at least one year at any of eight North American styrene-butadiene rubber plants. Analyses used standardised mortality ratios (SMRs) to compare styrene-butadiene rubber workers' cause specific mortalities (1943-91) with those of the United States and Ontario general populations. RESULTS: On average, there were 25 years of follow up per subject. The standardised mortality ratio (SMR) was 87 (95% confidence interval (95% CI) 85 to 90) for all causes of death combined and was 93 (95% CI 87 to 99) for all cancers. There was an excess of leukaemia (SMR 131, 95% CI 97 to 174), restricted to hourly workers (SMR 143, 95% CI 104 to 191). For causes of death other than leukaemia, SMRs were close to or below the null value of 100. Results by work area (process group) were unremarkable for non-Hodgkin's lymphoma, multiple myeloma, and stomach cancer. Maintenance workers had a slight increase in deaths from lung cancer, and certain subgroups of workers had more than expected deaths from cancer of the large intestine and the larynx. CONCLUSION: This study found an excess of leukaemia that is likely to be due to exposure to butadiene or to butadiene plus other chemicals. Deaths from non-Hodgkin's lymphoma, multiple myeloma, and stomach cancer did not seem to be related to occupational exposure. The excess deaths from lung cancer among maintenance workers may be due in part to confounding by smoking, which was not controlled for, and in part to an unidentified occupational exposure other than butadiene or styrene. Increases in cancer of the large intestine and larynx were based on small numbers, did not seem to be due to exposure to butadiene or styrene, and may be chance observations.

Butadienes↗

Workplace risk factors for cancer in the German rubber industry: Part 2. Mortality from non-respiratory cancers.

OBJECTIVES: To determine the mortality from non-respiratory cancers by work area among active and retired male workers of the German rubber industry. METHODS: A cohort of 11,633 male German workers was followed up for mortality from 1 January 1981 to 31 December 1991. Cohort members were active (n = 7536) or retired (n = 4127) on 1 January 1981 and had been employed for at least one year in one of five study plants producing tyres or technical rubber goods. Work histories were reconstructed from routinely documented "cost centre codes" and classified into six categories: I preparation of materials; II production of technical rubber goods; III production of tyres; IV storage and dispatch; V general service; VI others. Standardised mortality ratios (SMRs) and 95% confidence intervals (95% CIs), controlling for age and calendar year and stratified by work area (employment in respective work area for at least one year) and time related variables (year of hire, lagged years of employment in work area) were calculated from national mortality rates as the reference. RESULTS: Significant increases in mortality were found for pharyngeal cancer in work area IV (three deaths, SMR 486, 95% CI 101 to 1419), oesophageal cancer in work area III (11 deaths, SMR 227, 95% CI 114 to 407), and leukaemia in work areas I (11 deaths, SMR 216; 95% CI 108 to 387) and II (14 deaths, SMR 187; 95% CI 102 to 213). Furthermore, increased SMRs were found for stomach cancer in work area I (22 deaths, SMR 134; 95% CI 84 to 203), colon cancer in work area II (27 deaths, SMR 131, 95% CI 86 to 191), prostatic cancer in work area V (27 deaths, SMR 152, 95% CI 99 to 221), and bladder cancer in work areas IV (six deaths, SMR 253; 95% CI 93 to 551) and V (12 deaths, SMR 159, 95% CI 82 to 279). Mortality from cancer of the liver or gall bladder, pancreas and kidney, and from lymphomas was not substantially increased in any of the work areas. CONCLUSIONS: Mortality from cancer of several sites was associated with specific work areas. Some of these associations have been reported previously. Future analyses of our study will have to determine the role of specific exposures in the aetiology of these cancers.

Adult↗

Exposure to high concentrations of nitrosamines and cancer mortality among a cohort of rubber workers.

OBJECTIVES: To examine if the occurrence of different cancers was increased among rubber workers, as the highest known exposures of humans to nitrosamines have occurred in the rubber industry. METHODS: A cohort of 8933 rubber workers (hired after 1 January 1950, still active or retired on 1 January 1981 and employed for at least 1 year in one of five study factories) was followed up for mortality from 1 January 1981 to 31 December 1991. Work histories were reconstructed with routinely documented cost centre codes, which allowed identification by employment in specific work areas. For each cost centre code time and factory specific, semi-quantitative exposures to nitrosamines (three levels: low, medium, high) and other compounds were estimated by industrial hygienists. Rate ratios for medium (RRm) and high (RRh) exposures and 95% confidence intervals (95% CIs) were calculated with Cox's proportional hazards models with the low exposure as reference. RESULTS: Exposure to nitrosamines was significantly associated with an increased mortality from cancers of the oesophagus (13 deaths: RRm 1.7, 95% CI 0.3 to 10.3; RRh 7.3, 95% CI 1.9 to 27.8) and of the oral cavity and pharynx (17 deaths: RRm 0.8, 95% CI 0.2 to 4.1; RRh 3.9, 95% CI 1.4 to 11.1). A non-significant trend of increasing mortality with exposure to higher concentrations of nitrosamines was found for mortality from cancer of the prostate (26 deaths: RRm 1.4, 95% CI 0.5 to 3.8; RRh 2.2, 95% CI 0.9 to 5.6), and the brain (six deaths: RRm 3.9, 95% CI 0.3 to 42.6; RRh 6.0, 95% CI 0.6 to 57.6). No association was found between exposure to nitrosamines and cancer of the stomach (RRm 0.8, 95% CI 0.4 to 1.8; RRh 1.2, 95% CI 0.5 to 2.5) or lung (RRm 1.0, 95% CI 0.6 to 1.5; RRh 1.0, 95% CI 0.7 to 1.6). CONCLUSIONS: Exposure to high concentrations of nitrosamines is associated with increased mortality from cancers of the oesophagus, oral cavity, and pharynx, but not with increased mortality from cancers of the stomach or lung.

Adult↗

Cohort mortality and cancer incidence survey of recent entrants (1982-91) to the United Kingdom rubber industry: preliminary findings.

OBJECTIVES: To monitor the occurrence of stomach and lung cancer in a newly defined cohort of United Kingdom rubber workers and to report findings for other cancers in an early period of follow up. METHODS: A prospective cohort of 9031 male and female workers from 42 United Kingdom rubber factories has been enumerated. All employees had a minimum of 12 months employment and were first employed at one of the participating factories in the period 1982-91. Mortality data were available for the period 1983-98 and cancer registration data for the period 1983-94. The mortality and cancer incidence experienced by the cohort were compared with expected values based on national rates defined by period, age, and sex. RESULTS: Mortality from lung cancer was close to expectation (men: observed (obs) 11, expected (exp) 12.70, standardised mortality ratio (SMR) 87, 95% confidence interval (95% CI) 43 to 155; women: obs 0, exp 1.34, SMR 0, 95% CI 0 to 275). Mortality from stomach cancer was unexceptional (men: obs 1, exp 2.69, SMR 37, 95% CI 1 to 207; women: obs 0, exp 0.24, SMR 0, 95% CI 0 to 1537). Many statistical comparisons were made both for mortality data and for cancer registration data; only one difference between observed and expected numbers was significant (mortality from cancer of the testis: obs 3 exp 0.51, SMR 589, 95% CI 122 to 1722). Corresponding findings for incident cancers of the testis were unexceptional (obs 5, exp 5.13, standardised registration ratio (SRR) 97, 95% CI 32 to 227). CONCLUSION: The findings should be treated with caution as they relate to an early period of follow up. Nevertheless, they hold out the prospect that the increased SMRs for stomach and lung cancers reported for historical cohorts of United Kingdom rubber workers may not be apparent in more recent cohorts.

Adult↗

Exposure related mutagens in urine of rubber workers associated with inhalable particulate and dermal exposure.

AIMS: To determine the relation of the inhalation and dermal exposure routes and mutagenic activity in the urine of rubber workers (n = 105). METHODS: Mutagenic activity of ambient total suspended particulate matter (TSPM), surface contamination wipes, and Sunday and weekday urine samples was assessed with S typhimurium YG1041 in the presence of a metabolic activation system. Each subject was grouped into one of two exposure categories for dermal exposure (high (>/=25 revertants/cm(2)), low (<25 revertants/cm(2))) based on the mutagenic activity detected on likely skin contact surfaces and into two airborne mutagenic exposure categories (high (>/=210 revertants/m(3)), low (<210 revertants/m(3))). The potential influence of skin aberrations and acetylation status (NAT2) on urinary mutagenicity levels was also evaluated. RESULTS: A non-significant increase of +1605 revertants/g creatinine in urinary mutagenicity during the workweek relative to levels observed on Sunday was observed for the total population. Subsequent multivariate regression analyses, with the subjects' weekday urinary mutagenicity levels as the dependent variable, revealed associations with environmental and mainstream tobacco smoke exposure, with the level of mutagenic contamination on surfaces with which the subjects had likely contact, with the subjects' inhalable particulate exposure level, with observed mild skin aberrations, and when the subjects had a slow acetylation phenotype. Similar associations, although weaker were observed with Sunday urinary mutagenicity levels as well, except for the association with slow acetylation phenotype. Based on measured exposure levels it could be estimated that a high potential for exposure to surface contamination with mutagenic activity increased weekday urinary mutagenicity by about 62% when compared to low exposed workers, while high inhalable particulate exposure levels increased weekday urinary mutagenicity levels by about 21%. Subjects with mild skin aberrations had an additional, non-significant, increase in weekday urinary mutagenic activity compared to subjects without any skin aberrations. DISCUSSION: Results suggest that the dermal exposure route may contribute more to the level of genotoxic compounds in urine of rubber workers than the inhalation route. Although the study was limited in size, the results warrant further investigation in the importance of and ways to effectively control the dermal exposure route in the rubber industry.

Acetylation↗

Contact dermatitis of the ear due to a rubber earplug.

We report a case of contact dermatitis of the ear canal due to rubber earplugs. A 31-year-old Japanese woman had a 2-year history of eczema confined to her ears. Applications of various topical steroids had shown no beneficial effect upon her lesions. Considering contact dermatitis as a possible diagnosis we performed patch tests. Positive eczematous patch test results were obtained with mercaptobenzothiazole, tetramethylthiuram disulfide and her rubber earplugs, which she had used whenever she took a bath. The eruption cleared after the patient stopped using the rubber earplugs.

Adult↗

Rubber and plastic ammunition lethal injuries: the Israeli experience.

Rubber and plastic ammunition was used by the Israeli Defence Forces between the years 1987 and 1993 (Intifada) almost exclusively as a deterrent to aggression by the Palestinian civilian population in the occupied territories of Gaza, Judea and Samaria. While designed to avoid the serious wounds and deaths caused by the use of conventional military ammunition, the firing of rubber and plastic bullets has resulted in extensive injuries and more than 20 deaths. The data from the autopsies of 17 of these victims, mostly teenagers, were analysed. Ten of the victims died from injuries inflicted by Improved Rubber Bullets, while the other seven succumbed to injuries caused by Plastic Bullets. In most instances, the cause of death was related to injuries to the brain. Ballistic features of non-conventional bullets are discussed, and suggestions to curtail the serious injuries and fatalities arising from their use are given, with emphasis on firing from a safe range. British and South African experience with this type of ammunition is compared with our observations.

Adolescent↗

Biopurification of industrial waste gas from rubber regeneration.

By using the biopurifying technology, the organic waste gas in low concentrations emitted from the rubber-regeneration process was purified in this research. The result of the 100-day continuous running test of the industrial test device indicated that the purification efficiency of toluene in the rubber-regeneration waste gas could be maintained at about 90% for a long period of time and the treated waste gas could meet the China National Emission Standard. The cost of waste gas biotreatment was about 0.12-0.14% of rubber-regeneration production value of the factory. The biopurifying technology of waste gas displayed its excellent technical advancement and economic rationale. The following industrialized device was run continuously and passed the examination and acceptance by the local EPA.

Air Pollutants↗

Cloning and characterization of farnesyl diphosphate synthase from the rubber-producing mushroom Lactarius chrysorrheus.

Farnesyl diphosphate is involved in rubber biosynthesis as an initiating substrate for both polyprenol and mushroom rubber. So far, we have isolated the cDNA of a farnesyl diphosphate synthase (FPS) for the first time from a rare rubber-producing mushroom, Lactarius chrysorrheus, by the degenerate RT-PCR technique based on sequence information of FPS genes from fungi and yeasts. The open reading frame was clarified to encode a protein of 381 amino acid residues with a calculated molecular weight of 42.9 kDa. The deduced amino acid sequence of L. chrysorrheus FPS showed about 50% identity with those of other fungi and yeasts as well as plants. We expressed the cDNA of L. chrysorrheus FPS in Escherichia coli as a glutathione-S-transferase (GST)-fusion protein. The purified obtained protein showed FPS activity in which geranyl diphosphate (GPP) served as primary substrate, with a 2.4-fold higher k(cat)/K(m) value for GPP than for dimethylallyl diphosphate (DMAPP).

Agaricales↗

Chemistry of rubber processing and disposal.

The major chemical changes during the processing of rubber occur with the breakdown in mastication and during vulcanization of the molded tire. There is little chemical change during the compounding, calendering, extrusion, and molding steps. Reclaiming is the process of converting scrap rubber into an unsaturated, processible product that can be vulcanized with sulfur. Pyrolysis of scrap rubber yields a complex mixture of liquids, gas, and residue in varying ratios dependent on the nature of the scrap and the conditions of pyrolysis.

Carbon↗