Antioxidant supplementation and respiratory functions among workers exposed to high levels of ozone

Ozone exposure has been related to adverse respiratory effects, in particular to lung function decrements. Antioxidant vitamins are free-radical scavengers and could have a protective effect against photo-oxidant exposure. To evaluate whether acute effects of ozone on lung functions could be attenuated by antioxidant vitamin supplementation, we conducted a randomized trial using a double-blind crossover design. Street workers (n = 47) of Mexico City were randomly assigned to take daily a supplement (75 mg vitamin E, 650 mg vitamin C, 15 mg beta carotene) or a placebo and were followed from March to August 1996. Pulmonary function tests were done twice a week at the end of the workday. During the follow-up, the mean 1-h maximum ozone level was 123 ppb (SD = 40). During the first phase, ozone levels were inversely associated with FVC (beta = -1.60 ml/ppb), FEV1 (beta = -2.11 ml/ppb), and FEF25-75 (beta = -4.92 ml/ppb) (p < 0.05) in the placebo group but not in the supplement group. The difference between the two groups was significant for FVC, FEV1, and FEF25-75 (p < 0.01). During the second phase, similar results were observed, but the lung function decrements in the placebo group were smaller, suggesting that the supplementation may have had a residual protective effect on the lung. These results need to be confirmed in larger supplementation studies.     

Evaluation of workers exposed to elemental mercury using quantitative tests of tremor and neuromuscular functions

Workers exposed to metallic mercury vapor were subjects for tremor, EMG, and psychomotor tests. Regression analysis revealed statistically significant trends in these test results related to workers' urine mercury histories. Effects were subclinical, functionally insignificant and most associated with those workers whose urine mercury had exceeded 0.5 mg/L in the previous year. In agreement with previous reports, effects were reversible upon reduction of mercury exposure.     

Clinical and functional evaluation of health status of workers exposed to infrasound, noise and general vibration

The article covers complex evaluation of health state in building industry workers engaged into ferro-concrete production in St. Petersburg. The health state was considered under combined action of infrasound, noise and general vibration. Clinical and functional evaluation included medical examination by doctors, blood biochemistry and CBC, ECG, computer integral rheography, voice audiometry. Data for 62 moulders helped to assess acoustic environment at workplace and to reveal the morbidity structure.     

Diurnal rhythm of serum osteocalcin in normal children

The aim of the present study was to assess diurnal levels of serum osteocalcin in normal children using a recently introduced fluoroimmunoassay (Pharmacia Osteocalcin CAP FEIA) measuring solely the intact peptide. Five girls and two boys aged 10.4-13.6 (mean 12.2) y were studied. Blood samples for determination of osteocalcin were collected every 2h throughout the day. A statistically significant rise in serum osteocalcin (F = 6.7, p < 0.001) with a peak at 08.00 h and a nadir lasting from 10.00 to 24.00 h was found. Trough and peak levels (at 16.00 and 08.00 h, respectively) were 41.6 +/- 6.8 and 66.0 +/- 10.5 microg l(-1) (mean +/- SEM). The circadian variation should be taken into consideration when single assessments of serum osteocalcin in children are performed.     

Mortality of aerospace workers exposed to trichloroethylene

We assessed the differential effects of a chronotherapeutic agent (controlled-onset extended release [COER] verapamil), administered at bedtime versus a conventional, homeostatic therapy (nifedipine gastrointestinal therapeutic system [GITS]) taken in the morning, on early morning and 24-hour blood pressure (BP), heart rate (HR), and the HR x systolic BP product. The study was a multicenter (n = 51), randomized, double-blind prospective clinical trial with a 10-week treatment period. Dose titration was performed by study investigators based on systolic and diastolic BP values at the doctor's office. Ambulatory BP monitoring was performed at placebo baseline, after 4 weeks of stable double-blind therapy, and at end of the study. Twenty-four-hour BP profiles were studied in 557 hypertensive patients. Changes in BP, HR, slope of the rate of rise of BP and HR, and the HR-systolic BP product during the 4 hours from 1 hour before to 3 hours after awakening were evaluated. The study was powered to show equivalence between the 2 regimens, predefined as a difference between treatment groups in mean change from baseline in early morning BP of +/- 5 mm Hg systolic and +/- 3 mm Hg diastolic. Changes in the early morning BP fell within the definition of equivalence for the 2 treatment strategies (-12.0/-8.2 mm Hg for COER-verapamil and -13.9/-7.3 mm Hg for nifedipine GITS). Changes in both the early morning HR and rate-pressure product were significantly greater following COER-verapamil therapy versus nifedipine GITS (HR, -3.8 beats/minute vs +2.6 beats/minute, p < 0.001 and HR-systolic BP product, -1,437 beats/min x mm Hg vs -703 beats/min x mm Hg, respectively, p < 0.001). Changes in ambulatory BP demonstrated clinically similar reductions for the awake period, but nifedipine GITS lowered systolic BP to a greater extent than COER-verapamil during sleep (-11.0 vs -5.8 mm Hg, p < 0.001). COER-verapamil and nifedipine GITS had equivalent effects (+/- 5/3 mm Hg) on early morning BP. In addition, both extended-release calcium antagonists effectively lowered 24-hour BP. However, COER-verapamil had greater effects than nifedipine GITS on early morning hemodynamics (HR, HR-systolic BP product, rate of rise of BP and HR) and lesser effects during sleep due to its intrinsic pharmacologic properties and chronotherapeutic delivery system.     

Management of healthcare workers exposed to pertussis

The epidemiology of pertussis has changed in recent years. First, pertussis in adults is far more common than previously thought. Second, in many instances, the disease in adults is atypical or asymptomatic. Third, adult pertussis occurs despite a prior history of full immunization and, indeed, in persons with a prior history of natural disease. Large outbreaks of pertussis have occurred in healthcare facilities through failure to recognize and isolate infected infants and children, failure to recognize and treat disease in staff members, and failure to institute control measures rapidly. Appropriate use of work restriction and erythromycin prophylaxis may decrease the likelihood of institutional outbreaks.     

Mental disorders in workers exposed to chemicals at work

The article considers data on boundary psychic disorders in subjects exposed to chemicals of I-II jeopardy classes. Chemical factor appears to increase risk of psychiatric diseases. The authors suggest periodic psychiatric examination of workers engaged into hazardous chemical production for better occupational selection, early diagnosis and treatment of boundary psychic disorders.     

Levels of erythropoietin in serum of workers exposed to manganese

In workers exposed to manganese, compared with the no influence the change erythropoietin serum and concentration haemoglobin. Increased number red blood cell in 1 mm3 of peripheral blood in workers exposed to manganese and increased haematocrit value we can acknowledge result condensation blood.     

Neurophysiological findings among workers occupationally exposed to styrene

Ninety-six male workers occupationally exposured to styrene in 24 plants producing reinforced polyester plastic products were studied neurophysiologically. The mean age of the subjects was 29.6 +/- 7.4 years, and the duration of the exposure varied from 6 months to 14 years (mean 5.0 years). Mandelic acid concentration in the urine (mean of five values determined during five consecutive weeks) was used as the measure of exposure. The individual means of the mandelic acid concentrations varied from 7 to 4,715 mg/dm3 (median 808 mg/dm3). Neurotoxic effects of styrene exposure upon the central nervous system were revealed by abnormalities in the EEG. The overall prevalence of abnormal EEGs was 24% (23 out of 96), which is higher than that found among a normal population (p less than 0.05). Abnormal EEGs were found in one-third of the subjects with relevant styrene exposure (mandelic acid concentration over 700 mg/dm3), while low-level styrene exposure did not increase the prevalence of normal EEGs above that found in a normal population. Nerve conduction velocity measurements performed on 40 subjects did not reveal any definite relationship between neuropathy and styrene exposure. The EEG examination is useful in the investigation of the neurotoxic effects of styrene. Whenever a possibility exists of excessive styrene exposure or beginning poisoning, the workers should be submitted to an EEG examination.     

Immunological markers among workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

OBJECTIVES: To examine the association of immune cell number and function with occupational exposure to substances contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). METHODS: A cross sectional medical survey. The exposed participants were employed at two chemical plants between 1951 and 1972 in the manufacture of 2,4,5-trichlorophenate and its derivatives. The reference group consisted of people with no occupational exposure to phenoxy herbicides who lived within the communities of the workers. Data from a total of 259 workers and 243 unexposed referents were included in the analysis of immune function. Laboratory tests for immune status included enumeration of circulating leukocyte and lymphocyte populations, proliferative responses of circulating lymphocytes to mitogens and antigens, and serum concentrations of the major immunoglobulins and complement factor C3. RESULTS: The workers had substantial exposure to substances contaminated with TCDD, as indicated by a lipid adjusted mean serum TCDD concentration of 229 ppt compared with a mean of 6 ppt in the unexposed referents. Workers were divided into categories based on their serum TCDD concentration. For all categories except the lowest, with values of serum TCDD comparable with the unexposed referents, there were increased odds of having lower counts of CD26 cells (activated T cells) (odds ratio (OR) 1.0, 95% confidence interval (95% CI) 0.5 to 1.8 for TCDD < 20 ppt; OR 1.6, 95% CI 0.8 to 3.2 for TCDD 20-51 ppt; OR 2.7, 95% CI 1.4 to 5.1 for TCDD 52-125 ppt; OR 2.6, 95% CI 1.4 to 4.9 for TCDD 125-297 ppt; OR 2.4, 95% CI 1.3 to 4.6 for TCDD 298-3389 ppt). A less consistent finding was decreased spontaneous proliferation of cultured lymphocytes. However, increases were found in proliferation of lymphocytes in response to concanavalin and pokeweed in workers in the high TCDD category. Age, cigarette smoking, and alcohol were significant predictors of several immunological outcomes. CONCLUSIONS: Associations between serum TCDD concentration and both a decrease in circulating CD26 cells and decreased spontaneous background proliferation were the major findings of this study. These results are unlikely to be of clinical importance but may reflect limited evidence for an association between immunological changes in workers and high serum concentrations of TCDD, or chance findings resulting from the evaluation of multiple immunological variables.     

Respiratory disease among workers exposed to man-made mineral fibers

Fibrous glass and mineral wool workers exposed to airborne man-made mineral fibers prior to 1964 were identified and followed for deaths caused by respiratory disease. Fiber exposure levels were estimated for each worker. Average fiber concentrations were very low in relation to a National Institute of Occupational Safety and Health recommendation that exposure to man-made mineral fibers less than 3.5 microns in diameter be limited to 3 fibers per cubic centimeter of air. Fibrous glass workers were exposed to about one hundredth and mineral wool workers to about one tenth of that amount. Respiratory cancer death rates were not excessive for the fibrous glass workers, but they were significantly elevated for the mineral wool workers. When respiratory cancer deaths were compared with fiber exposure levels, however, there was in no instance a strong positive correlation. There was a significant excess in nonmalignant respiratory disease deaths (excluding influenza and pneumonia) for fibrous glass workers and for the total cohort. When these nonmalignant respiratory disease deaths were compared with fiber exposure levels, however, there was in no instance a strong positive association. A special study was made of workers exposed to small diameter fibers. Respiratory cancer deaths were not in excess; however, there was an excess in nonmalignant respiratory disease deaths. This study provided no consistent evidence of a respiratory disease hazard related to exposure to man-made mineral fibers among the workers who produce these fibers. Results must be interpreted in relation to the relatively low exposure levels for these workers.     

Medical surveillance studies of workers exposed to low level benzene

The paper presents th results of an investigation of haematotoxicity in workers exposed to low benzene concentrations. Forty-seven female workers in the shoemaking industry, exposed to solvent mixture and twenty-seven non-exposed controls were examined. Benzene concentrations in the working atmosphere ranged from 1.9 to 14.8 ppm. Significant differences in the levels of benzene in blood and phenols in pre- and post-shift urine between the exposed and control groups confirmed benzene exposure. Haemoglobin level and mean corpuscular haemoglobin concentration were significantly lower, and mean corpuscular volume was higher in the shoemaking workers than in controls. In the subgroup of shoemaking workers exposed to benzene concentrations of 5 ppm or lower, no differences in haematological parameters were found. In conclusion, exposure to a benzene concentration lower than 5 ppm does not appear to produce an increased level of abnormal haematological outcomes detectable in routine medical surveillance. The results of the study corroborate the present maximum permissible concentrations (5 ppm) as a protective limit preventing the onset of haematotoxic non-leukemogenic effects of chronic benzene exposure.     

Early neuropsychological dysfunctions in workers exposed to benzene and its homologues

Empiric therapy is practical and must be begun promptly; the specific regimen chosen must be based upon local conditions and epidemiology. It must be recalled that subgroups of patients are not necessarily equivalent to the majority, i.e., there are low-risk patients for whom ambulatory and/or oral therapy is appropriate and, conversely, there are high-risk patients who have a potential for a high mortality and who, while perhaps few in number, are of critical importance. Further, many of these patients are very complex, and this leads to a high level of physician concern and insecurity. This physician concern, in turn, leads to a tendency to modify regimens, given that the physician all too often is dealing with inadequate diagnostic information owing to the patient situation. The physician's choice of modification is highly dependent upon knowledge of the regimen the patient is already receiving. There is a need for clear definition of endpoints, and these must be established before the study is initiated. All too many published studies are too small to evaluate the endpoint that has been defined, and many others, although sufficient in size, have all of the problems inherent in studies conducted at multiple sites by multiple individuals with differing degrees of commitment or enthusiasm toward the study at hand. A few implications for study design and evaluation seem evident: it is critical to define endpoints and execute the study accordingly. This means determining the size of the population needed and determining the presence or absence of risk groups. Patients to be excluded e.g., those in whom infection is doubted must be selected on the basis of objective data by an observer blinded to both the outcome and the treatment. Similarly, the classification of response should preferably be done by an observer not influenced by knowledge of the therapy being given. Finally, and similarly, the decision to modify therapy (especially if modification is equivalent to defining failure with the regimen) should not be influenced by knowledge of the therapy being administered.     

Borderline mental disorders in workers exposed to poisons and their prevention

Studies covered psychic state in workers exposed to poisons. The authors represent clinical and epidemiologic principles of the disorders formation, the prevalence and structure of the disorders caused by various hazards. The article necessitates up-to-date data-processing system for occupational selection, clinical, psychophysiologic, biochemical and experimental psychologic evaluation of current state in workers engaged into liquidation of chemical weapons.     

Neurono-glial changes in the cerebral cortex of animals exposed to white noise

The rat acoustic cortex has been studied at light optic and ultrastructural levels under the white noise stimulation. After the noise stimulation for 7 days, micropunctate hemorrhages, proliferation and hypertrophy in cells of microglia and astrocytic glia are noted. After the noise stimulation for 21 days, the neuroglial reaction becomes less pronounced, there are no hemorrhages, a great amount of neurons with peripheral and total chromatolysis appear. In other neurons, as well as in all types of neuroglia the number of primary lysosomes increases, their structure changes. In lysosomes lipofuscin and lipid drops are accumulating, many of lysosomes turning into multivesicular bodies. The destructive changes observed in the neurons and neuroglia underlie prolonged disturbances in the higher neural activity after the noise stimulation is stopped.     

Anti-p53 antibodies in sera of workers occupationally exposed to vinyl chloride

BACKGROUND: The p53 tumor suppressor gene (also known as TP53) is often mutated in a wide variety of cancers, including angiosarcoma of the liver (ASL). Anti-p53 antibodies have been detected in the sera of patients with leukemia, childhood lymphoma, or cancers such as those of the breast, lung, colon, esophagus, and liver (hepatocellular carcinoma). PURPOSE: The objective of this study was to determine the prevalence and time of appearance of serum anti-p53 antibodies during the pathogenesis of ASL associated with occupational exposure to vinyl chloride. METHODS: Enzyme-linked immunoassay (EIA) was used to detect anti-p53 antibodies in 148 serum samples from 92 individuals occupationally exposed (in France or in Kentucky) to vinyl chloride; 15 of these individuals (six from France and nine from Kentucky) had ASL. A subset of coded EIA-positive and EIA-negative sera was further analyzed for anti-p53 antibodies by immunoblotting and immunoprecipitation. Nucleotide sequence analysis of exons 5-8 of the p53 gene was conducted on ASL DNA from six patients. We tested sera from 31 men who had no occupational exposure to vinyl chloride; they made up the control group. Statistical analyses were done using the Kruskal-Wallis chi-squared approximation and the Wilcoxon two-sample test for normal approximation. All P values result from two-sided tests. RESULTS: Fourteen serum samples (from nine individuals) were positive in the EIA. Five of the 15 individuals with ASL were positive for anti-p53 antibodies by EIA, immunoblotting, and immunoprecipitation: one individual at 11.3 and 10.8 years before diagnosis, another at 4 months before and shortly after diagnosis, and three when diagnosed or shortly thereafter. Four of the 77 vinyl chloride-exposed workers without diagnosed ASL were positive for anti-p53 antibodies; two of the four had symptoms related to vinyl chloride toxicity. Tumors from three of the six vinyl chloride-exposed workers from which sufficient DNA for analysis was obtained had A:T to T:A missense mutations of the p53 gene. Anti-p53 antibodies were detected in two of these individuals. Among the control group, two of 15 serum samples from 15 lung cancer patients and zero of 15 serum samples from control subjects without cancer had anti-p53 antibodies as substantially lower levels than the nine (10%) of 92 vinyl chloride-exposed workers who were positive for anti-p53 antibodies. CONCLUSIONS AND IMPLICATIONS: Serum anti-p53 antibodies can predate clinical diagnosis of certain tumors, such as ASL, and may be useful in identifying individuals at high cancer risk, such as workers with occupational exposure to vinyl chloride.