An evaluation of the standardized chipping hammer test specified in ISO 8662-2.
(57/360)
OBJECTIVES: Prolonged exposure to severe chipping hammer vibration may cause hand-arm vibration syndrome. A reliable test method is required to select appropriate tools and assist in the development of better chipping hammers. In the present study, the ISO standardized test method (ISO 8662-2, 1992) was examined through an investigation of the vibration characteristics of chipping hammers operating on the energy absorber specified in the standard. METHODS: The energy absorber and test setup were designed and constructed based on those specified in the standard. The experiment employed six subjects and used two pneumatic chipping hammers and three different feed forces (50, 100 and 200 N). The subject posture was the same as that specified in the standard. RESULTS: The vibration emission at the tool dominant frequency (or air blow rate) generally declined with an increase in feed force, thus decreasing the frequency-weighted accelerations. The increase in feed force, however, resulted in an increase in the unweighted vibration emission at high frequencies. The chipping hammer vibration emission operating on the energy absorber at the high feed force (200 N) was inconsistent. CONCLUSIONS: The measurement method has a good repeatability except at a high feed force. The feed force has a significant effect on the vibration emission. The single feed force specified in the standard may not be sufficient to test the tool behaviors. Multiple levels of feed force should be used for the chipping hammer test. Doing so may provide a more appropriate basis for tool screening. (+info)
Worker exposure to polychlorinated biphenyls in elastic polysulphide sealant renovation.
(58/360)
Worker exposure to polychlorinated biphenyls (PCBs) in renovation of prefabricated houses was assessed by biological monitoring of 24 PCB congeners including the 10 most abundant PCBs in elastic polysulphide sealants. Serum samples from 22 exposed and 21 non-exposed men were analysed using gas chromatography-mass spectrometry with negative chemical ionization. Total PCB concentration of 24 PCB congeners in workers' serum varied between 0.6 and 17.8 microg/l (mean 3.9 microg/l, median 1.9 microg/l). The Finnish upper reference limit for occupationally non-exposed persons (3 microg/l) was exceeded in the serum samples of 10 workers. Concentrations for non-exposed persons were 0.3-3.0 microg/l (mean 1.7 microg/l, median 1.5 microg/l). The concentration for the sum of the 10 most abundant PCB congeners in elastic polysulphide sealants in serum samples taken in autumn after the renovation season was 2-10 times higher than in samples from the same workers (n=5) taken in the previous spring. The concentrations of PCB congeners PCB 28, 52, 77, 101, 138, 153 and 180 in hygienic samples taken from the breathing zone of the workers were low, ranging from not detected to 3.1 microg/m3. The concentrations of PCB 28 and 52 in sera were positively correlated with the concentrations in air samples taken from the breathing zone of six workers (r=0.70 and 0.80). (+info)
Cement, cancers and clusters: an investigation of a claim of a local excess cancer risk related to a cement works.
(59/360)
BACKGROUND: We investigated claims by a campaigning group of a cancer cluster associated with a local cement works. METHODS: To investigate cancer rates in the town we defined the study area as the Census wards matching the geographical area code supplied to the campaigning group. Standard methods were applied to registered cases of cancer for the area for the years 1974-1989 to derive observed and expected numbers. The significance of the relative risk was assessed using the Poisson distribution. By selecting a different denominator population we attempted to reproduce the results of the campaign group. Cancer rates around the cement works were investigated for four cancer types plausibly associated with emissions, using cancer registrations for the years 1985-1994. Cases were mapped to 1981 Census ward boundaries, and the same statistical methods were used, but expected counts were also adjusted for deprivation. Rates were calculated for an inner 2 km zone and outer zone 2-5 km from the works. Relative risk was calculated and the ratio of risks was examined for evidence of increased risk closer to the works. RESULTS: Relative risks were not significantly elevated either in the town or around the cement works itself. We were able to reproduce the likely errors that resulted in the elevated relative risks for five cancer groups claimed by the campaigning group. CONCLUSIONS: We found no evidence of increased incidence of cancer around the cement works. Incorrect handling of cancer registration data can result in spurious cancer clusters and unnecessary public alarm. (+info)
Evaluation of 4 intervention strategies to prevent the mechanical transmission of porcine reproductive and respiratory syndrome virus.
(60/360)
Four intervention strategies were tested for their ability to prevent the mechanical transmission of porcine reproductive and respiratory syndrome virus (PRRSV): the use of disposable plastic boots to prevent contamination of personal footwear, the use of boot baths to disinfect PRRSV-contaminated plastic boots, the use of plastic slatted (Polygrate) flooring in the anteroom to prevent PRRSV contamination of incoming personal footwear, and the use of bag-in-a-box shipping methods to prevent PRRSV contamination of the contents of a container destined for a swine farm. Ten PRRSV-positive replicates and 10 PRRSV-negative (sham-inoculated) replicates were used for each strategy. Swabs were collected from selected sites and tested by TaqMan polymerase chain reaction for PRRSV RNA and by swine bioassay to confirm the presence of infectious PRRSV. Results indicated that the use of disposable boots, bleach boot baths or bag-in-a-box shipping methods was highly efficacious in preventing mechanical transmission of PRRSV. In contrast, the use of Polygrate flooring in the anteroom did not prevent contamination of personal footwear. The numbers of PRRSV-positive samples from the Polygrate surface and the soles of incoming footwear placed directly on the Polygrate surface were not significantly different (P = 0.24) from those of footwear that directly contacted the floor of the contaminated anteroom. Although these results are promising, this study should be considered a pilot project and the intervention strategies not considered biosecurity protocols. The model used may or may not represent field conditions. Therefore, the information should be used to develop larger experimental studies, with sufficient statistical power, in combination with field-based epidemiologic studies to better assess the role of mechanical transmission of PRRSV under field conditions. (+info)
Cumulative exposure to dust and gases as determinants of lung function decline in tunnel construction workers.
(61/360)
AIMS: To study the relation between lung function decrease and cumulative exposure to dust and gases in tunnel construction workers. METHODS: A total of 651 male construction workers (drill and blast workers, tunnel concrete workers, shotcreting operators, and tunnel boring machine workers) were followed up by spirometric measurements in 1989-2002 for an average of six years. Outdoor concrete workers, foremen, and engineers served as a low exposed referent population. RESULTS: The between worker component of variability was considerably reduced within the job groups compared to the whole population, suggesting that the workers within job groups had similar exposure levels. The annual decrease in FEV1 in low-exposed non-smoking workers was 21 ml and 24 ml in low-exposed ever smokers. The annual decrease in FEV1 in tunnel construction workers was 20-31 ml higher than the low exposed workers depending on job group for both non-smokers and ever smokers. After adjustment for age and observation time, cumulative exposure to nitrogen dioxide showed the strongest association with a decrease in FEV1 in both non-smokers, and ever smokers. CONCLUSION: Cumulative exposure to nitrogen dioxide appeared to be a major risk factor for lung function decreases in these tunnel construction workers, although other agents may have contributed to the observed effect. Contact with blasting fumes should be avoided, diesel exhaust emissions should be reduced, and respiratory devices should be used to protect workers against dust and nitrogen dioxide exposure. (+info)
Effects on the peripheral nervous system of tunnel workers exposed to acrylamide and N-methylolacrylamide.
(62/360)
OBJECTIVES: This study evaluates the possible toxic effects on the peripheral nervous system of tunnel workers exposed to acrylamide and N-methylolacrylamide during grouting work. METHODS: Symptoms and nerve conduction velocities (NCV) were recorded for 24 tunnel workers 4 and 16 months after the cessation of exposure during grouting operations. Fifty tunnel workers not involved in grouting operations served as referents. Exposure was assessed by questionnaires, qualitative exposure indices, and measurements of hemoglobin adducts after the cessation of exposure. RESULTS: The exposed workers reported a higher prevalence of symptoms during grouting work than they did in an examination 16 months later. A statistically significant reduction in the mean sensory NCV of the ulnar nerve was observed 4 months postexposure when compared with the values of the reference group (52.3 versus 58.9 m/s, P = 0.001), and the mean ulnar distal delay was prolonged (3.1 versus 2.5 ms, P = 0.001). Both measures were significantly improved when measured 1 year later. Exposure-related improvements were observed from 4 to 16 months postexposure for both the median (motor and sensory NCV and F-response) and ulnar (sensory NCV, F-response) nerves. A significant reversible reduction in the mean sensory amplitude of the median nerve was also observed, while the mean sensory amplitude of the sural nerve was significantly reduced after 16 months. CONCLUSIONS: The results indicate demyelinating and axonal changes in peripheral nerves of tunnel workers in relation to exposure to N-methylolacrylamide and acrylamide during grouting operations. The changes were slight, mostly subclinical, and most of the effects were reversible, with normalization after 1 year. (+info)
Cancer mortality and morbidity among Lithuanian asbestos-cement producing workers.
(63/360)
OBJECTIVES: This study investigated the incidence of cancer and cause-specific mortality among workers in the two Lithuanian asbestos-cement factories. METHODS: The study included 1887 asbestos-cement workers, 1285 men and 602 women, and 37000 person-years. The two factories were active from 1956 (A) and 1963 (B), and the workers were observed from 1978 to 2000. The analysis was based on a comparison between the observed and expected numbers of cancer and causes of death. The observed numbers of cancer were obtained through linkage with the national cancer registry. The date and causes of death were obtained from two different sources. The expected numbers were calculated on the basis of gender- and age-specific incidence and mortality rates in 5-year periods from the whole country. Standardized incidence ratios (SIR) and standardized mortality ratios (SMR) and 95% confidence intervals (95% CI) were calculated. Duration of employment and time since first exposure were used as indicators of exposure. RESULTS: During the follow-up, 1978-2000. 473 deaths were observed versus 489 expected. There was no excess risk of deaths from nonmalignant respiratory diseases, except for an elevated risk of mortality in relation to the digestive organs other than cancer, 18 observed versus 12.2 expected (95% CI 0.9-2.3). There was no excess risk for any types of cancer, except for colorectal cancer in men, 17 observed cases (SIR 1.6, 95% CI 1.6-2.6) and one case of mesothelioma in a woman. CONCLUSIONS: This study on asbestos-exposed workers did not show any excess risk of respiratory cancer or deaths of pneumoconiosis. (+info)
Building camps and work related injuries.
(64/360)
AIMS: To focus on one possible predictor of reported work related injuries--the role of living in building-site camps versus daily commuting from home to construction sites. METHODS: A cohort of construction workers was collected, based on personnel files from contractors involved in the building of the Great Belt Bridge. The files included information on employment periods and whether or not the employees lived in building-site camps. The cohort was followed up for injuries reported to the National Work Environment Authority. RESULTS: Construction workers living in camps reported 217 accidents, of which 24 were serious or fatal. Among those not living in camps we found 262 accidents, of which 29 were serious or fatal. The relative risk for all accidents for camp versus non-camp was 0.84 (95% CI 0.69 to 1.00). The respective figure for serious or fatal accidents was RR = 0.85 (95% CI 0.47 to 1.52). CONCLUSION: Results suggest that high accident rates at large construction sites may be reduced, if commuting is replaced by living on-site. (+info)