(25/7118) Silica dust and lung cancer in the German stone, quarrying, and ceramics industries: results of a case-control study.
BACKGROUND: A work force based case-control study of lung cancer was performed in non-silicotic subjects exposed to crystalline silica to investigate the association between silica dust and lung cancer excluding the influence of silicosis. METHODS: Two hundred and forty seven patients with lung cancer and 795 control subjects were enrolled, all of whom had been employed in the German stone, quarrying, or ceramics industries. Smoking was used as a matching criterion. Exposure to silica was quantified by measurements, if available, or otherwise by industrial hygienists. Several indices (peak, average and cumulative exposure) were used to analyse the relationship between the level of exposure and risk of lung cancer as odds ratios (OR). RESULTS: The risk of lung cancer is associated with the year of and age at first exposure to silica, duration of exposure, and latency. All odds ratios were adjusted for these factors. Considering the peak exposure, the OR for workers exposed to high levels (>/=0.15 mg/m3 respirable silica dust which is the current occupational threshold value for Germany) compared with those exposed to low levels (<0.15 mg/m3) was 0.85 (95% CI 0.58 to 1. 25). For the time weighted average exposure the OR was 0.91 (95% CI 0.57 to 1.46). The OR for the cumulative exposure was 1.02 (95% CI 0. 67 to 1.55). No increase in risk was evident with increasing exposure. CONCLUSIONS: This study shows no association between exposure to crystalline silica and lung cancer. The exclusion of subjects with silicosis may have led to dilution with respect to the level of exposure and therefore reduced the power to detect a small risk. Alternatively, the risk of getting lung cancer may be restricted to subjects with silicosis and is not directly linked to silica dust. (+info)
(26/7118) Low mortality rates in industrial cohort studies due to selection for work and survival in the industry.
Occupational groups are often described as being relatively healthy because their mortality rates are lower than those of the national average. Although correct this confuses the issue for those who are interested in assessing the effects of exposure to a particular chemical. In a further analysis of data collected in a study of all men ever exposed to vinyl chloride monomer in the manufacture of polyvinyl chloride in Great Britain, three factors have been shown to contribute to the low mortality rates that were observed. The three factors: the selection of a healthy population for employment, the survival in the industry of the healthier men, and the length of time that this population has been pursued, have been quantified. The mortality experience within five years of entering this industry was shown to be as low as 37% of that expected; for circulatory disease and respiratory disease it was as low as 21%. There was a progressive increase in standardized mortality ratio with the length of time since entry so that the effect had almost disappeared 15 years after entry. To avoid confounding the selection effect with the survival effect the latter was measured by separating men who survived 15 years after entering the industry according to whether or not they were still in the industry after this period. Those who had left experienced an overall standardized mortality ratio some 50% higher than those still in the industry. This effect, although consistent in the age groups between 25 and 74 years and for all cause groups studied, was greatest in those aged between 25 and 44 years and for lung cancer and respiratory disease. (+info)
(27/7118) Cancer mortality and morbidity among plutonium workers at the Sellafield plant of British Nuclear Fuels.
The mortality of all 14 319 workers employed at the Sellafield plant of British Nuclear Fuels between 1947 and 1975 was studied up to the end of 1992, and cancer incidence was examined from 1971 to 1986, in relation to their exposures to plutonium and to external radiation. The cancer mortality rate was 5% lower than that of England and Wales and 3% less than that of Cumbria. The significant excesses of deaths from cancer of the pleura and thyroid found in an earlier study persist with further follow-up (14 observed, 4.0 expected for pleura; 6 observed, 2.2 expected for thyroid). All of the deaths from pleural cancer were among radiation workers. For neither site was there a significant association between the risk of the cancer and accumulated radiation dose. There were significant deficits of deaths from cancers of mouth and pharynx, liver and gall bladder, and larynx and leukaemia when compared with the national rates. Among all radiation workers, there was a significant positive association between accumulated external radiation dose and mortality from cancers of ill-defined and secondary sites (10-year lag, P = 0.04), leukaemia (no lag, P = 0.03; 2-year lag, P = 0.05), multiple myeloma (20-year lag, P = 0.02), all lymphatic and haematopoietic cancers (20-year lag, P= 0.03) and all causes of death combined (20-year lag, P= 0.008). Among plutonium workers, there were significant excesses of deaths from cancer of the breast (6 observed, 2.6 expected) and ill-defined and secondary cancers (29 observed, 20.1 expected). No significant positive trends were observed between the risk of deaths from cancers of any specific site, or all cancers combined, and cumulative plutonium and external radiation doses. For no cancer site was there a significant excess of cancer registrations compared with rates for England and Wales. Analysis of trends in cancer incidence showed significant increases in risk with cumulative plutonium plus external radiation doses for all lymphatic and haematopoietic neoplasms for 0-, 10- and 20-year lag periods. Taken as a whole, our findings do not suggest that workers at Sellafield who have been exposed to plutonium are at an overall significantly increased risk of cancer compared with other radiation workers. (+info)
(28/7118) Presence of specific IgG antibody to grain dust does not go with respiratory symptoms.
A high prevalence of work-related symptoms in relation to grain dust exposure has been reported in grain dust workers, but the role of the specific IgG antibody is unknown. To study the possible role of specific IgG (sIgG) and specific IgG4 (sIgG4) in the development of work-related symptoms, sIgG and sIgG4 subclass antibodies against grain dust antigens were determined by ELISA in sera from 43 workers and 27 non-exposed controls. They were compared with results of specific IgE antibodies, exposure intensity and the presence of respiratory symptoms. SIgG and sIgG4 antibodies were detectable in almost all sera of exposed workers, and the prevalence were significantly higher than those of controls (p<0.05). Higher sIgG4 was noted in workers with specific IgE (p<0.05). The correlation between sIgG and exposure duration was significant (p<0.05). There was no association between the prevalence of sIgG and sIgG4 and the presence of respiratory symptoms, or work stations. In conclusion, these results suggest that the existence of sIgG and sIgG4 might represent a response to grain dust exposure and may unlikely play a role in the etiology of respiratory symptoms. (+info)
(29/7118) Toxic polyneuropathy of shoe-industry workers. A study of 122 cases.
The toxic polyneuropathy observed in a group of shoe-industry workers in Italy was clinically characterised by a symmetrical prevalently distal motor deficit, with occasional marked weakness of pelvic girdle muscles, and frequently by only subjective sensory symptoms; non-specific disturbances usually preceded neurological signs. Subclinical cases of 'minimal' chronic neuropathy, characterised by alterations of a neurogenic type in the EMG without a reduction of motor nerve conduction velocity, were also observed. Worsening of the clinical picture, with further lowering of nerve conduction velocity, was noted in some cases up to four months after removal from the toxic environment. In the most severe cases clinical recovery took up to three years. The electromyographic and electroneurographic features were consistent with a mixed axonal neuropathy, with clear prevalence of the damage in the distal part of the nerve (dying-back neuropathy). Volatile substances, such as n-hexane and other low boiling point hydrocarbons found in high percentage in solvents and glues, are suggested as the causative agent. (+info)
(30/7118) Failure of many ophthalmologists to use lasers safely.
In 1990, after the detection of impairment of colour discrimination in laser operators, the College of Ophthalmologists recommended safety guidelines for the use of lasers. We measured the effectiveness of these guidelines and their impact on ophthalmological practice in the United Kingdom. Previously, in ophthalmologists not following the guidelines, there was a deterioration in colour discrimination after a laser session. No such deterioration was found in 10 ophthalmologists tested who adhered to the guidelines, but their colour discrimination was significantly worse than that of controls. Replies to a questionnaire disclosed that one third of senior ophthalmologists were unaware of the practices recommended. (+info)
(31/7118) Magnetic measurements of pulmonary contamination.
The magnitic determination of pulmonary contamination is based on the remanent magnetization of ferromagnetic contaminating particles. The remanent field of the externally magnetized particles is proportional to their amount and shows their distribution. Although only magnetizable particles are detected with this method, the amount of the inhaled ferromagnetic substance can be used when the total dust exposure of the worker is estimated. In this work five shipyard welders were studied. First the particles disposed to the lungs were externally magnetized and then their distribution was mapped with a sensitive magnetometer. The magnitudes of the remanent fields measured from the welders differed from the fields measured from controls by several orders of magnitude. The radiographic findings showed a good correlation with the magnetic measurements, and further experiments will prove whether this method can partly replace presently used radiological investigations. (+info)
(32/7118) Lymphatic and hematopoietic cancer in teachers.
A recent study found high rates of leukemia and related disorders among teachers. This finding may be related to exposure to childhood infections. Therefore, epidemiologic studies on the risk of lymphatic and hematopoietic cancer among teachers were systematically reviewed. Altogether 26 relevant investigations were identified, most from ad hoc publications rather than from scientific journals. Elevated risks of leukemia, lymphoma, and multiple myeloma were found in studies using proportional mortality or mortality odds ratios as outcome measures. However, these observations may reflect low overall mortality and do not necessarily indicate high death rates from the cancers of interest. In studies deriving standardized mortality or incidence ratios, the risk estimates were generally lower. The most striking finding was for non-Hodgkin's lymphoma (approximate summary relative risk 1.36, 95% confidence interval 1.13-1.62), but it was likely to have been exaggerated by publication bias. In conclusion, no compelling epidemiologic evidence exists for a hazard of leukemia or related diseases among teachers. (+info)