Respiratory cancer in a cohort of copper smelter workers: results from more than 50 years of follow-up.
(57/1747)
Several studies have linked inhalation of airborne arsenic with increased risk of respiratory cancer, but few have analyzed the shape of the exposure-response curve. In addition, since inhaled airborne arsenic affects systemic levels of inhaled arsenic, there is concern that inhaled arsenic may be associated with cancers of the skin, bladder, kidney, and liver, which have been linked to ingested arsenic. The authors followed 8,014 white male workers who were employed for 12 months or more prior to 1957 at a Montana copper smelter from January 1, 1938 through December 31, 1989. A total of 4,930 (62%) were deceased, including 446 from respiratory cancer. Significantly increased standardized mortality ratios (SMRs) were found for all causes (SMR = 1.14), all cancers (SMR = 1.13), respiratory cancer (SMR = 1.55), diseases of the nervous system and sense organs (SMR = 1.31), nonmalignant respiratory diseases (SMR = 1.56), emphysema (SMR = 1.73), ill-defined conditions (SMR = 2.26), and external causes (SMR = 1.35). Internal analyses revealed a significant, linear increase in the excess relative risk of respiratory cancer with increasing exposure to inhaled airborne arsenic. The estimate of the excess relative risk per mg/m3-year was 0.21/(mg/m3-year) (95% confidence interval: 0.10, 0.46). No other cause of death was related to inhaled arsenic exposure. (+info)
The relative bioavailability and metabolism of bisphenol A in rats is dependent upon the route of administration.
(58/1747)
Bisphenol A (BPA) is used to produce polymers for food contact applications, thus there is potential for oral exposure of humans to trace amounts via the diet. BPA was weakly estrogenic in screening assays measuring uterine weight/response, although much higher oral doses of BPA were required to elicit a uterotropic response as compared to other routes of administration. The objective of this study was to determine if a route dependency exists in the pharmacokinetics and metabolism of 14C-labeled BPA following single oral (po), intraperitoneal (ip), or subcutaneous (sc) doses of either 10 or 100 mg/kg to Fischer 344 rats. Results indicated a marked route dependency in the pharmacokinetics of BPA. The relative bioavailability of BPA and plasma radioactivity was markedly lower following oral administration as compared to sc or ip administration. The major fraction of plasma radioactivity following oral dosing was the monoglucuronide conjugate of BPA (68-100% of plasma radioactivity). BPA was the major component in plasma at Cmax following sc or ip administration exceeded only by BPA-monoglucuronide in females dosed ip. Up to four additional unidentified metabolites were present only in the plasma of animals dosed ip or sc. One of these, found only following ip administration, was tentatively identified as the monosulfate conjugate of BPA. The monoglucuronide conjugate was the major urinary metabolite; unchanged BPA was the principal component excreted in feces. These results demonstrated a route dependency of BPA bioavailability in rats, with oral administration resulting in the lowest bioavailability, and offer an explanation for the apparent route differences in estrogenic potency observed for BPA. (+info)
Occupational exposures and pancreatic cancer: a meta-analysis.
(59/1747)
OBJECTIVES: Consolidation of epidemiological data on pancreatic cancer and worksite exposures. METHODS: Publications during 1969-98 were surveyed. Studies without verified exposures were excluded. Meta-analyses were conducted on data from 92 studies covering 161 populations, with results for 23 agents or groups of agents. With a standard format, five epidemiologists extracted risk estimates and variables of the structure and quality of each study. The extracted data were centrally checked. Random meta-models were applied. RESULTS: Based on 20 populations, exposure to chlorinated hydrocarbon (CHC) solvents and related compounds was associated with a meta-risk ratio (MRR) of 1.4 (95% confidence interval (95% CI) 1.0 to 1.8). Nickel and nickel compounds were considered in four populations (1.9; 1.2 to 3.2). Excesses were found also for chromium and chromium compounds (1.4; 0.9 to 2.3), polycyclic aromatic hydrocarbons (PAHs) (1.5; 0.9 to 2.5), organochlorine insecticides (1.5; 0.6 to 3.7), silica dust (1.4; 0.9 to 2.0), and aliphatic and alicyclic hydrocarbon solvents (1.3; 0.8 to 2.8). Evidence on pancreatic carcinogenicity was weak or non-positive for the following agents: acrylonitrile (1.1; 0.0 to 6.2); arsenic (1.0; 0.6 to 1.5); asbestos (1.1; 0.9 to 1.5); diesel engine exhaust (1.0; 0.9 to 1.3); electromagnetic fields (1.1; 0.8 to 1.4); formaldehyde (0. 8; 0.5 to 1.0); flour dust (1.1; 0.3 to 3.2); cadmium and cadmium compounds (0.7; 0.4 to 1.4); gasoline (1.0; 0.8 to 1.2); herbicides (1.0; 0.8 to 1.3); iron and iron compounds (1.3; 0.7 to 2.5); lead and lead compounds (1.1; 0.8 to 1.5); man-made vitreous fibres (1.0; 0.6 to 1.6); oil mist (0.9; 0.8 to 1.0); and wood dust (1.1; 0.9 to 2.5). The occupational aetiological fraction of pancreatic cancer was estimated at 12%. In a subpopulation exposed to CHC solvents and related compounds, it was 29%; to chromium and chromium compounds, 23%; to nickel and nickel compounds, 47%; to insecticides, 33%; and to PAHs, 33%. CONCLUSION: Occupational exposures may increase risk of pancreatic cancer. High quality studies are called for on interactions between occupational, environmental, and lifestyle factors as well as interactions between genes and the environment. (+info)
Exposure-response relations for self reported asthma and rhinitis in bakers.
(60/1747)
OBJECTIVES: To explore relations between two estimates of exposure to inhalable flour dust, and the incidence rates (IRs) of asthma and rhinitis in bakers. METHODS: This was a retrospective cohort study among 2923 bakers. A posted questionnaire registered the disease and work history. For every year, each baker was assigned an estimate of the exposure concentration to inhalable flour dust derived from reported job-tasks and dust measurements. Exposure at onset of disease was expressed as current dust exposure concentration, and as cumulative dose of exposure to dust. A multiple Poisson regression analysis assessed the impacts of the exposure estimates on the IRs of asthma and rhinitis. RESULTS: IRs of asthma and rhinitis increased by dust concentration at onset of disease. The IR of asthma for the bakers with highest exposure (dough makers) was 7. 3/1000 person-years in men and 6.5 in women and for rhinitis 43.4 and 38.5, respectively. There was a significant association between the dust concentration at onset of disease and the risk for asthma or rhinitis, but not of the cumulative exposure. CONCLUSION: The risk of asthma seemed to be increased at inhalable dust concentrations >/=3 mg/m(3) (dough making or bread forming), whereas the risk of rhinitis was increased at all concentrations >/=1 mg/m(3), indicating an increased risk in all bakery job-tasks. The risks seemed to be less dependent on the cumulative exposure dust than the inhalable dust concentrations. (+info)
Haematological and spermatotoxic effects of ethylene glycol monomethyl ether in copper clad laminate factories.
(61/1747)
OBJECTIVES: To investigate the effects of ethylene glycol monomethyl ether (EGME) on haematology and reproduction in exposed workers. METHODS: 53 Impregnation workers from two factories that make copper clad laminate with EGME as a solvent were recruited as the exposed group. Another group of 121 lamination workers with indirect exposure to EGME was recruited as the control group. Environmental monitoring of concentrations of EGME in air and biological monitoring of urinary methoxyacetic acid (MAA) concentrations were performed. Venous blood was collected for routine and biochemical analyses. Semen was collected from 14 workers exposed to EGME for sperm analysis and was compared with 13 control workers. RESULTS: Results of haematological examination showed that the haemoglobin, packed cell volume, and red blood cell count in the male workers exposed to EGME were significantly lower than in the controls. The frequency of anaemia in the exposed group (26.1%) was significantly higher than in the control group (3.2%). However, no differences were found between the female workers exposed and not exposed to EGME. After adjustment for sex, body mass index, and duration of employment, red blood cell count was significantly negatively associated with air concentrations of EGME, and haemoglobin, packed cell volume, and red blood cell count were significantly negatively associated with urinary concentrations of MAA. The pH of semen in the exposed workers was significantly lower than in the control workers, but there were no significant differences in the sperm count or sperm morphology between the exposed and control groups. CONCLUSION: It can be concluded that EGME is a haematological toxin, which leads to anaemia in the exposed workers. However, the data from this study did not support the theory of a spermatotoxic effect of EGME. (+info)
Aerobic degradation of dinitrotoluenes and pathway for bacterial degradation of 2,6-dinitrotoluene.
(62/1747)
An oxidative pathway for the mineralization of 2,4-dinitrotoluene (2, 4-DNT) by Burkholderia sp. strain DNT has been reported previously. We report here the isolation of additional strains with the ability to mineralize 2,4-DNT by the same pathway and the isolation and characterization of bacterial strains that mineralize 2, 6-dinitrotoluene (2,6-DNT) by a different pathway. Burkholderia cepacia strain JS850 and Hydrogenophaga palleronii strain JS863 grew on 2,6-DNT as the sole source of carbon and nitrogen. The initial steps in the pathway for degradation of 2,6-DNT were determined by simultaneous induction, enzyme assays, and identification of metabolites through mass spectroscopy and nuclear magnetic resonance. 2,6-DNT was converted to 3-methyl-4-nitrocatechol by a dioxygenation reaction accompanied by the release of nitrite. 3-Methyl-4-nitrocatechol was the substrate for extradiol ring cleavage yielding 2-hydroxy-5-nitro-6-oxohepta-2,4-dienoic acid, which was converted to 2-hydroxy-5-nitropenta-2,4-dienoic acid. 2, 4-DNT-degrading strains also converted 2,6-DNT to 3-methyl-4-nitrocatechol but did not metabolize the 3-methyl-4-nitrocatechol. Although 2,6-DNT prevented the degradation of 2,4-DNT by 2,4-DNT-degrading strains, the effect was not the result of inhibition of 2,4-DNT dioxygenase by 2,6-DNT or of 4-methyl-5-nitrocatechol monooxygenase by 3-methyl-4-nitrocatechol. (+info)
Epidemiological survey of workers exposed to inorganic germanium compounds.
(63/1747)
OBJECTIVES: To assess occupational exposure to inorganic germanium (Ge) in workers from a producing plant, and to assess the health of these workers, with a special focus on respiratory, kidney, and liver functions. METHODS: Cross sectional study of 75 workers exposed to Ge and 79 matched referents. Exposure was characterised by measuring air and urine concentrations of the element during a typical working week, and health was assessed by a questionnaire, clinical examination, lung function testing, chest radiography, and clinical chemistry in serum and urine, including high and low molecular weight urinary proteins. RESULTS: Airborne concentrations of Ge (inhalable fraction) ranged from 0.03 to 300 micrograms/m, which was reflected by increased urinary excretion of Ge (0.12-200 micrograms/g creatinine, after the shift at the end of the working week). Lung, liver, and haematological variables were not significantly different between referents and workers exposed to Ge. A slightly higher urinary concentration of high molecular weight proteins (albumin and transferrin) was found in workers exposed to Ge, possibly reflecting subclinical glomerular changes. No relation was found between the intensity or duration of exposure and the urinary concentration of albumin. No difference between referents and workers exposed to Ge was found for other renal variables. CONCLUSIONS: Measurement of urinary Ge can detect occupational exposure to inorganic Ge and its compounds. It is prudent to recommend the monitoring of renal variables in workers exposed to Ge. (+info)
Cancers in concrete workers: results of a cohort study of 33,668 workers.
(64/1747)
OBJECTIVES: To study cancer morbidity patterns in concrete workers. METHODS: A cohort of 33,503 concrete workers was enrolled in the study from 1971-86. The average duration of follow up was 19.4 years (582,225 person-years). The workers' cancer morbidity was compared with the morbidity of the general population. RESULTS: A total of 3572 incident cancers were observed. Significantly increased standardised incidence ratios (SIRs) were found for all malignant neoplasms (SIR 107; 95% confidence interval (95%CI) 103 to 110), cancer of the lip (SIR 179; 95%CI 134 to 234), cancer of the stomach (SIR 139; 95%CI 122 to 158), cancer of the lung (SIR 125; 95%CI 114 to 137), and cancer of the prostate (SIR 108; 95%CI 101 to 116). Reduced risk was found for cancer of the large intestine (SIR 80; 95%CI 69 to 93) and cancer of the testis (SIR 50; 95%CI 26 to 87). Smoking was more prevalent among the concrete workers than in the general population (50% v 35%). CONCLUSION: The study has shown a slightly increased overall risk of cancer among concrete workers. The increased risk of lung cancer could entirely be due to differences in smoking habits between concrete workers and the general population. There is a possibility that the smoking also has contributed to the increased risks of stomach cancer and lip cancer, but occupational factors may have contributed to these cancer sites. (+info)