Physiological Responses to Thermal Stress in a Glass Bangle Factory

The physiological responses to thermal radiation (46·2± 5·1°C) and high ambient temperature (38·2± 3·4°C) were recorded in 77 glass bangleworkers over the work shift in a glass bangle factory at Firozabad.The oral temperature showed a mean rise of 2·2°Fover the work shift in the exposed workers in comparison toa 1·2°F rise observed in the control group. The maximumincrease in oral temperature (2·5°F)was recordedin Sikiyas and pahalwalas who worked near the Sikai furnacewhile Babalwalas showed the lowest rise (1·2°F) inthe oral temperature. The peak value of oral temperature wasrecorded at 16.00 h. The working heart rate also exhibited amean rise of 24 beats/min in the bangle workers as result ofexposure to thermal radiation. The greatest increase in heartrate (30·5 beats/min) was recorded in Fireman and thesmallest increase (20·3 beats/min) in Battiwalas. Thepeak value of heart rate was also observed at 16.00 h in thebangle workers. Respiratory function studies revealed pulmonaryhyperventilation in the exposed workers caused by an increasein tidal volume and breathing frequency while the control groupdid not show any significant increase in pulmonary ventilationover the day's work. The sweat loss and the associated bodydehydration was maximally recorded in the Firemen working nearthe main furnace. The extent of dehydration varied from 0·81per cent to 2·47 per cent in the glass bangle workers.However, body dehydration was below the tolerance limit. Thechanges observed in the physiological functions revealed cardio-respiratoryinstability and physiological strain in the glass bangle workersexposed to the hot environment prevailing in this industry. Requests for reprints should be addressed to: Dr. S. K. Rastogi, Industrial Toxicology Research Centre, Mahatma Gandhi Marg, P.O. Box 80, Lucknow 226001, India     

Cardiorespiratory and thermal effects of wearing gas protective clothing

Summary Six healthy men aged 25 to 37 walked on a treadmill at work levels of 21 and 41% of their for 25 to 30 min wearing gas protective clothing (GPC) consisting of an impermeable suit with a self-contained breathing apparatus (total weight 25 kg) or shorts (control tests, CT) in a temperate environment (t _a 24.3°C ± 1.0°C, rh 30–50%). When the GPC was worn at 21 and 41% , the most prominent increases, compared with the CT, were noted in the heart rate ( ± SE, 120 ± 5 vs 76 ± 3 beats min^–1 and 171 ± 5 vs 103 ± 3 beats min^–1), mean skin temperature (36.1 ± 0.2 vs 31.3° C ± 0.1°C and 36.9 ± 0.3 vs 30.9°C ± 0.4°C) and sweat rate (473 ± 51 vs 70 ± 23 g m^–2 h^–1 and 766 ± 81 vs 135 ± 18 g m^–2 h^–1) indicating a high cardiovascular and thermoregulatory strain, which was not decreased by ventilating the suit with an air flow of 281 min^–1 at 41% . The ventilation, oxygen consumption and production of carbon dioxide increased in relation to the extra weight of the GPC, partly dependent on the dynamic work level. It was concluded that the increase in the physiological load caused by the GPC was so high that the work-rest regimens, workers' level of physical fitness, cardiovascular health and heat tolerance should be considered whenever gas protective clothing is used.     

Wet-bulb globe temperature index: a predictor of physiological strain in hot environments.

The readings of the natural wet-bulb (tnwb) and globe thermometer for computing Twbg index (indoors) were taken between 08.00 to 17.00 h at two-hour intervals in different work locations in the glass bangle and brassware industries. For assessing the physiological reliability of the Twbg index for heat stress, the radial pulse rate was monitored at two-hour intervals in 60 brassware workers and 77 glass bangle workers (mean ages: 25.3 +/- 8.8 and 28.1 +/- 5.7 years) belonging to various occupations exposed to thermal radiation for 9.3 +/- 8.5 and 11.2 +/- 4.8 years respectively. The mean values of Twbg index observed in the brassware and glass bangle industries were found to be almost of the same order (34.4 +/- 3.0 degrees C and 35.2 +/- 1.1 degrees C). The radiant heat seemed to make the most significant contribution to the environmental heat stress in these industries. The globe temperature near the main melting furnace was as high as 53.8 +/- 3.0 degrees C and 59.2 +/- 4.02 0C in the glass bangle and brassware industries respectively. It was, therefore, expected that the exposed workers would show pronounced physiological strain. Surprisingly the pulse rates of these workers did not indicate any significant physiological strain since the maximal pulse rates recorded did not exceed the safe limits of circulatory strain recommended by the WHO.(ABSTRACT TRUNCATED AT 250 WORDS)     

Work load and physiological responses during asbestos removal with protective clothing

Summary The removal of asbestos-containing building materials requires the use of dust-repelling protective clothing and a respirator. The present study was aimed at measuring physiological responses to asbestos removal in actual work situations. The subjects were eight asbestos workers. During the work, the men wore permeable or impermeable clothing along with a powered or non-powered filtering device including a full-face or half-face mask. Environmental parameters, work postures, heart rate (HR), the skin temperature at two sites and the rectal temperature were recorded every minute during work. Perceived exertion, thermal sensation, thermal comfort, and skin wetness were rated by the subjects. The ambient temperature at work sites ranged from 19° to 37.5°C and relative humidity, from 21% to 50%. The mean HR ranged from 101 to 141 beats min^–1. The calculated (from HR measurements) average oxygen consumption (VO₂) varied from 0.9 to 1.9 1 min^–1 , which corresponded to 27%–60% of the maximal value. The peak rectal temperature and the highest mean of two measurements of skin temperature were 37.7° ± 0.3° C and 34.4° ± 0.9°C, respectively. The sweat rate varied from 162 to 583 g h^–1. Poor work posture was common during asbestos removal. The arms were elevated over shoulder level for 35% of the work time. During the work the mean physiological strain was considered to be moderate, with some heavy peak loads being registered. The increases in HR and the thermal responses seemed to be due primarily to the use of simple, nonpowered hand tools, which often required the performance of heavy manual work with the arms held above shoulder level, and less to the protective clothing used. The heat strain during asbestos removal was not excessive because most of the work was done under thermoneutral conditions, and a rest pause of 10–15 min every hour also decreased the thermal strain during work. Improvements in work methods and tools are needed to reduce the peak loads and postural strain experienced during asbestos removal.This study was financially supported by the Finnish Work Environmental Fund     

A comparison of cardiac strain among drillers of two different age groups in underground manual coal mines in India

Cardiac strain was evaluated in terms of working heart rate (WHR), relative cardiac cost (RCC), net cardiac cost (NCC) and other recovery indices among six younger (mean age 34.2 +/- 2.7 yr) and sixteen older (mean age 48.9 +/- 5.4 yr) drillers working in a manual underground coal mine over two spells of work. The mean WHR was within the range of 117-132 beats / min with corresponding mean relative cardiac cost between 44-48% of heart rate reserve for the younger group and 53-55% for their older counterparts. The mean NCC was above 50 beats/min for both age groups. It was seen that the workers surpassed the recommended limits of cardiac strain indices. The intensity of workload indicates the job to be "heavy" to "extremely heavy" in accordance with the heaviness scales based on WHR, NCC and recovery heart rates. Heat stress prevailing in the workplace in terms of effective temperature (ET) and wet bulb globe temperature (WBGT), was above the recommended limits as per the guidelines proposed by WHO and ACGIH. High physiological demands of the job which requires predominate static muscular exertions coupled with high heat stress were found to hinder the recovery process and may prove deleterious particularly for the older workers. Therefore, in the present context, the need of ergonomic interventions for job organization and quick reparation of environmental condition are strongly indicted.     

Nutritional status and physical fitness of Polish miners and steel workers

Summary The nutritional status of 690 miners and 604 steel workers was determined. Their physical fitness was estimated by an indirect method using the Astrand Rhyming nomogram. The nutritional status parameters indicated an increase in weight in relation to increasing age: 57% of the subjects were overweight. Over 70% were current smokers. The mean value for V O₂max was 2.8 ± 0.51/min / 38 ± 7 ml/kg per min. The high percentage of subjects (Polish miners and steel workers) who eat too much, are overweight, smoke and who have a low physical-activity level during their leisure time demonstrates the risk for coronary heart disease.This work was supported by Poland's Central Program (C.P.B.R. 11.11.65) and by the Ministry of Health (6/MZ-IX/86-8)     

Oxygen and glucose consumption and lactate production of erythrocytes of workers exposed to inorganic lea

Summary Oxygen and glucose consumption and lactate production were measured at 37° C in samples of buffered suspensions of red cells from 39 subjects exposed occupationally to inorganic lead and from 24 non-exposed subjects. The same measurements were made in samples of red cells from normal blood and from suspensions or normal erythrocytes in saline, which had been incubated for 1 h at 37° C with varying amounts of added lead chloride. The haemoglobin concentration, the reticulocyte count, the stippled erythrocyte count, the concentration of coproporphyrin in urine, and the concentration of lead in blood were also determined in the workers exposed to lead.These conventional criteria indicated that the subjects were fairly heavily exposed, with some individuals in a state of mild poisoning. The washed erythrocytes from the exposed subjects, suspended in phosphate buffer, consumed more glucose during 3 h of observation (2.5 ± 0.4 M/ml (packed) cells·h[ =mean ± s. d.]) than did those from the non-exposed controls (2.2 ± 0.3 M/ml cells·h); the difference of the means was statistically highly significant (t = 3.88; p<0.001). The mean lactate production in samples of cells of the exposed workers (4.1 ± 0.5 M/ml cells·h) was slightly higher than in those of the controls (3.8 ± 0.7 M/ml cells·h), but the difference was not statistically significant. There was a statistically significant difference between the mean glycolytic quotients in the cells of the exposed people (0.85 ± 0.13) and those of the non-exposed controls (0.93 ± The oxygen consumption was identical within the experimental error in samples of both groups of subjects.There was a significant correlation between the glucose consumption in samples of erythrocytes of exposed subjects and the coproporphyrin concentration in urine of their respective donors. The findings are interpreted as likely to result from a shift towards a younger mean in the age distribution of the erythrocyte populations in samples of exposed workers as compared to those of non-exposed normal subjects, but other possible interpretations are also suggested. We conclude that (a) the previously reported deficiency in the potassium exchange of red cells from people exposed to inorganic lead is probably not due to a decreased rate of metabolic energy release in the cells; and that (b) the functional disturbance measured here in the red cells of the exposed people may reflect fairly well the overall effect of absorbed lead in the individuals' organisms.Final concentrations of 5 × 10^–9–5 × 10^–8M of lead chloride added in vitro into samples of whole blood or erythrocytes suspended in saline, which were incubated for I h at 37° C, did not affect the oxygen or glucose consumption nor the lactate production of the subsequently washed red cells resuspended in phosphate buffer at 37° C.Mrs S. Asp, M. A., drew the figures and performed the statistical calculations and Miss T. Lönnberg gave skilful technical assistance.Part of the material in this paper has been accepted for presentation at the XV International Congress of Occupational Health, Vienna, September 1966.The present work has been sponsored by a research grant from the Helena Lundqvist foundation to S. H.     

Continuous ambulatory electrocardiography among workers exposed to methylmethacrylate

Summary Methylmethacrylate (MMA), a widely used monomer in the manufacture of acrylic polymers, has been reported to cause cardiac troubles in industrial workers. The effects of MMA on the heart was assessed by continuous ambulatory electrocardiographic records. The study was performed in 22 occupationally exposed workers and in 18 healthy controls. Our study did not support the hypothesis that MMA is responsible for cardiomyodystrophy. However, supraventricular and ventricular ectopic beats were significantly more frequent among exposed workers versus controls (P < 0.01). Moreover, repolarization changes such as large T waves were noted only in exposed workers (eight cases against none in the control group). Although there was no clear connection between MMA exposure and the recorded cardiac changes in the exposed group, the role of MMA cannot be totally excluded.     

Application of an Enzyme-Linked Immunosorbent Assay for the Analysis of Paraquat in Human-Exposure Samples

Paraquat is a toxic quaternary ammonium compound used as an herbicide around the world. Easy, fast, and inexpensive but sensitive methods are needed to study the effects of long-term, low-level exposure of paraquat on human health. An enzyme-linked immunosorbent assay (ELISA) was used for quantification of paraquat in urine and air-filter samples collected in a human-exposure study among farm workers in Costa Rica. A sample pretreatment consisted of removal of interfering substances using solid-phase extraction resin columns. The precision and accuracy of the method were tested using duplicate spiked urine samples. The correlation between results for blind samples obtained using ELISA and liquid chromatography–mass spectrometry was significant (R²=0.945 and 0.906 for spiked and field samples, respectively). With an LOQ of 2 ng mL^–1, this ELISA method was able to distinguish the exposed from the nonexposed farm workers. For the air-filter analysis, paraquat was extracted by 9M H₂SO₄ at 60°C for 12 hours, and the results obtained by ELISA showed good correlation (R²=0.918) with the spectrophotometric (256 nm) measurements. Paraquat in acid-stabilized urine samples was very stable, and no significant losses were detected during a 3-month storage at room temperature, at 4°C, or at –20°C.     

Acute sodium bicarbonate loading has negligible effects on resting and exercise blood pressure but causes gastrointestinal distress

Oral ingestion of sodium bicarbonate (bicarbonate loading) has acute ergogenic effects on short-duration, high-intensity exercise. Because sodium bicarbonate is 27% sodium, ergogenic doses (ie, 300 mg?kg⁻¹) result in sodium intakes well above the Dietary Reference Intakes upper limit of 2300 mg/day. Therefore, it is conceivable that bicarbonate loading could have hypertensive effects. Therefore, we performed a double-blind crossover trial to evaluate the hypothesis that bicarbonate loading increases resting and exercise blood pressure (BP). A secondary hypothesis was that bicarbonate loading causes gastrointestinal distress. Eleven endurance-trained men and women (exercise frequency, 4.6 ± 0.4 sessions/wk; duration, 65 ± 6 min/session) underwent testing on two occasions in random sequence: once after bicarbonate loading (300 mg?kg⁻¹) and once after placebo ingestion. BP and heart rate were measured before bicarbonate or placebo consumption, 30 minutes after consumption, during 20 min of steady state submaximal cycling exercise, and during recovery. Bicarbonate loading did not affect systolic BP during rest, exercise, or recovery (P = .38 for main treatment effect). However, it resulted in modestly higher diastolic BP (main treatment effect, +3.3 ± 1.1 mmHg, P = .01) and higher heart rate (main treatment effect, +10.1 ± 2.4 beats per minute, P = .002). Global ratings of gastrointestinal distress severity (0-10 scale) were greater after bicarbonate ingestion (5.1 ± 0.5 vs 0.5 ± 0.2, P < .0001). Furthermore, 10 of the 11 subjects (91%) experienced diarrhea, 64% experience bloating and thirst, and 45% experienced nausea after bicarbonate loading. In conclusion, although a single, ergogenic dose of sodium bicarbonate does not appear to have acute, clinically important effects on resting or exercise BP, it does cause substantial gastrointestinal distress.     

Antioxidative stress response in workers exposed to carbon disulfide

Objective: To study the effects of carbon disulfide (CS₂) on antioxidative stress systems of exposed workers. Methods: Enzyme-linked immunosorbent assay (ELISA) and thiobarbituric acid test (BAT) were conducted on 67 exposed workers and 88 controlled ones in a viscose rayon factory to determine their serum cuprozinc-superoxide dismutase (CuZnSOD) and malonyldialdehyde (MDA) levels. Results: The average levels of CuZnSOD in workers exposed to CS₂ both above and below 10 mg/m³ were higher than those in the control group (P < 0.0001), showing some dose-effect and dose-response relationships. SOD levels increased when the exposure index (EI) was less than 300, and remained at a high level at the range of 300 to 900. When EI was higher than 900, SOD tended to decrease. Meanwhile, the serum MDA levels increased. Both CS₂ concentrations and exposure time contribute to the MDA levels. Conclusions: CS₂ exposure could influence the stress response of the oxidative-antioxidative system of workers. Increased SOD levels could be considered as the stress response of antioxidative system to CS₂ exposure in the early stages, and the influence of CS₂ on SOD might be bi-directional. SOD and MDA might become objective indices in workers' health surveillance. The role of these two indices in the intoxication mechanism still needs to be clarified. Received: 3 August 1999 / Accepted: 25 April 2000     

Assessment of occupational health problems and physiological stress among the brick field workers of West Bengal,India

Objectives

The brick field industry is one of the oldest industries in India, which employs a large number of workers of poor socioeconomic status. The main aim of the present investigation is i) to determine the prevalence of musculoskeletal disorders among brick field workers, ii) to determine the prevalence of respiratory disorders and physiological stress among brick field workers compared to control workers.

Material and Methods

For this study, a total of 220 brick field workers and 130 control subjects were selected randomly. The control subjects were mainly involved in hand-intensive jobs. The Modified Nordic Questionnaire was applied to assess the discomfort felt among both groups of workers. Thermal stress was also assessed by measuring the WBGT index. The pulmonary functions were checked using the spirometry. Physiological assessment of the workload was carried out by recording the heart rate and blood pressure of the workers prior to work and just after work in the field.

Results

Brick field workers suffered from pain especially in the lower back (98%), hands (93%), knees (86%), wrists (85%), shoulders (76%) and neck (65%). Among the brick-making activities, brick field workers felt discomfort during spading for mud collection (98%), carrying bricks (95%) and molding (87%). The results showed a significantly lower p value < 0.001 in FVC, FEV₁, FEV₁/FVC ratio and PEFR in brick field workers compared to the control group. The post-activity heart rate of the brick field workers was 148.6 beats/min, whereas the systolic and diastolic blood pressure results were 152.8 and 78.5 mm/Hg, respectively.

Conclusions

This study concludes that health of the brick field workers was highly affected due to working in unhealthy working conditions for a long period of time.     

Ventilatory dysfunction in glass bangle workers

The pulmonary function status of 73 glass bangle workers suffering from chronic bronchitis having varied exposures to pulmonary toxicants in the work environment was evaluated in 1984. The findings were compared with those observed in 220 asymptomatic glass bangle workers and 88 unexposed controls. There was a higher prevalence (45.2%) of ventilatory dysfunction in the chronic bronchitic cases as compared to 19% in the asymptomatic workers and 2.3% in controls, respectively. The relative risk of airway obstruction was 8.3 and 19.6 times higher in the asymptomatic and chronic bronchitic workers respectively as compared to the controls (p less than 0.001). The prevalence of obstructive impairment among the smokers and non-smokers in the exposed workers was not statistically significant. However, age greater than 30 was found to be significantly associated with bronchial obstruction in chronic bronchitic cases. The relative risk of duration of exposure was found to be 1.86 in the asymptomatic workers exposed for more than 10 years (p less than 0.05) while it was 1.62 in workers with chronic bronchitis. The occupational and environmental factors responsible for the high prevalence of chronic bronchitis and associated ventilatory dysfunction in relatively young glass bangle workers are discussed.     

Changes in hearing,cardiovascular functions,haemodynamics, upright body sway,urinary catecholamines and their correlates after prolonged successive exposures to complex environmental conditions

Summary This study deals with changes in temporary threshold shifts of hearing (TTS₂), cardiovascular functions (HR, SBP, DBP, PP, RWA), haemodynamic activity (HDI), upright body sway (VUBSA), ratios of urinary catecholamines (10A/DA, 10NA/DA, A/NA, NA/A) and correlations between these changes in complex exposure situations. The study was carried out in a special exposure chamber on 60 healthy male students. It was based on a factorial experimental design with a total of 12 exposure combinations. Each individual experiment took 6 h with a pause of 1 h at noon. There were 12 sequential exposure periods lasting 16 min each. A pause of 4 min followed each exposure period. The subjects were exposed to noise and whole body vibration at two different dry bulb temperatures. Noise classes were: (1) no noise, and (2) stable broad-band noise of 90 dBA. Vibration classes were: (1) no vibration, (2) a sinusoidal 5 Hz vibration, and (3) a stochastic vibration with a frequency range of 2.8 to 11.2 Hz along the Z-axis and with an acceleration of 2.12 m/s². Temperature classes were: (1) 20°C and (2) 35°C. Changes in body functions were registered during the pauses. Urine samples were gathered for the morning and afternoon sessions and for the preceding and the following night of the test. The changes were dependent on the combinations of noise, vibration and temperature to which the subjects were exposed. The TTS₂ values at 4 kHz were associated with the HDI-values when subjects were exposed simultaneously to noise and stochastic vibration at 35°C. The TTS₂ values at 6 kHz were associated most strongly with the HDI values after exposure to a combination of noise, stochastic or sinusoidal vibration and a temperature of 20°C. The TTS₂ values at 4 and 6 kHz correlated positively with the NA/A ratio when subjects were exposed to noise at 35°C. The association between TTS₂ values and the 10A/NA ratio and especially the A/NA ratio was very strong when subjects had been simultaneously exposed to noise and sinusoidal or stochastic vibration at 35°C. Furthermore, the highest positive correlation coefficients were found between TTS₂ values at 4 kHz and VUBSA values in the X-direction when subjects had been exposed to noise or simultaneously to noise and sinusoidal vibration at 20°C. With vibration exposure at 35°C, noise led to an increase in the 10NA/DA and NA/A ratios, but with vibration exposure at 20°C, noise decreased the 10NA/DA and NA/A ratios. The exposure was reflected as a rise in the NA/A ratio during the night following the experiment. The variance analytical model as a whole explained 58 to 62% in the morning and 55 to 60% in the afternoon (TTS₂ values at 4 kHz), 50 to 62% and 45 to 50% (TTS₂ values at 6 kHz), 9 to 12% and 9 to 19% (HR values), 16 to 31% and 23 to 36% (SBP values), 3 to 7% and 2 to 6% (DBP values), 7 to 12% and 9 to 13% (PP values), 5 to 8% and 1 to 3% (RWA values), 10 to 18% and 12 to 23% (HDI values), 6 to 7% and 7% (VUBSA values in X direction), 1% and 1 to 8% (VUBSA values in the Y direction), 18% and 20% (10A/DA), 17% and 20% (10NA/DA), 28% and 24% (A/NA), and 27% and 21% (NA/A) of the variation in the values of the variables involved. Some results were presented in Kanazawa, Japan, at the Second International Conference on the Combined Effects of Environmental Factors, September 28–October 1, 1986     

Modification of 24-h ambulatory blood pressure and heart rate during contraception with the vaginal ring: a prospective study

Background

Hypertension is recognized as a major risk factor for coronary, cerebral and renal vascular disease. Hormonal methods of contraception may increase the risk for cardiovascular events. We evaluated whether the combined hormonal contraceptive vaginal ring that releases 15-mcg ethinylestradiol and 120 mcg of etonogestrel each day influences 24-h ambulatory blood pressure.

Study Design

At baseline, ambulatory blood pressure was automatically monitored every 30 min for 41 h in 18 normotensive healthy women during their follicular phase (Days 3–6). Each subject was immediately treated with the vaginal ring for six cycles. Monitoring of ambulatory blood pressure was repeated in the last days of the sixth cycle of treatment.

Results

During the vaginal ring, a significant increase was observed for 24-h diastolic (2.75±5.13 mmHg; p=.03) and mean (2.69±5.35 mmHg; p=.048) blood pressure and for daytime diastolic (3.04±6.36 mmHg; p=.05) blood pressure. No variation was found in nighttime blood pressure. Heart rate increased in the 24-h period (3.39±5.85 beats/min; p=.025) and in the daytime (3.38±6.25 beats/min; p=.034) measurements.

Conclusions

In normotensive women, the vaginal ring slightly increases 24-h blood pressure and heart rate. The underlying mechanisms and the clinical impact of these slight modifications require further evaluation.     

Fluorocarbon 113 exposure and cardiac dysrhythmias among aerospace workers.

We investigated the cardiotoxic effects of 1,1,2-Trichloro-1,2,2- Trifluoroethane (fluorocarbon 113 or FC113) exposures among healthy workers cleaning rocket and ground support equipment for the National Aeronautic and Space Administration (NASA) programs. Exposure and ambulatory electrocardiographic (ECG) monitoring data were evaluated on 16 workers, each of whom was examined on exposed and nonexposed workdays. We examined whether there was a greater rate of dysrhythmias on an exposed workday relative to a nonexposed workday. Overall, we found no within subject differences in the rate of ventricular and supraventricular premature beats (number per 1,000 heart beats), fluctuations in the length of the P-R interval, or heart rate. We found that levels of FC113 exposures below the Occupational Safety and Health Administration (OSHA) 8-hour time-weighted-average (TWA) standard of 1,000 ppm did not induce cardiac dysrhythmias or subtle changes in cardiac activity. However, because fluorocarbons may sensitize the heart to epinephrine, this study's negative findings based on sedentary and fairly healthy workers may not be generalizable to other populations of workers who are not as healthy or engaged in more physically demanding work.     

48-hour ambulatory electrocardiography in dynamite workers and controls

ABSTRACT Sudden deaths and chronic cardiovascular diseases have been reported in excess frequency from the explosives industry. Forty-two active dynamite workers and 43 healthy, unexposed workers have been studied by ambulatory electrocardiographic monitoring during two 24-hour periods covering an exposed shift and the “abstinence phase,” 40-64 hours after the last exposure to dynamite. To achieve comparability the non-exposed individuals were screened for risk factors of heart disease in the same way as those employed in exposed work. No statistically significant differences were found between the groups concerning the mean individual number of ventricular or supraventicular ectopic beats per hour or per 10 000 heart beats during the whole recorded time. Among those who showed only ectopic beats in one of the two periods dynamite workers tended to have more ectopic beats in the second period. “Complicated” ventricular ectopic beats (multifocal, bigemeny, or coupled) were seen in six dynamite workers and four controls. The only observed period of ventricular tachycardia was seen in a dynamite worker on Monday morning. The mean individual corrected QT-time was similar between the two groups, and there was no tendency towards longer QT-times among the dynamite workers during the abstinence period. Continuous monitoring detected several cases with pronounced ventricular arrhythmias despite normal short-time ECG and may be used to investigate the heart rhythm in active workers.     

Hemolymph osmolality, acid-base balance, and ammonia excretion of Penaeus japonicus bate exposed to ambient nitrite

Penaeus japonicus Bate (11.43±1.41 g) were exposed individually in 30 ppt seawater to 0.01 (control), 0.07, 0.37, 0.72, and 1.43 mmol/L nitrite-N at 25°C for 24 h. Concentrations of hemolymph osmolality, acid-base balance, and ammonia-N excretion were examined. An increase in the ambient nitrite concentration significantly increased nitrite uptake, ammonia excretion, and hemolymph PO₂, and decreased hemolymph pH, PCO₂, TCO₂, HCO _inf3 ^sup– , and osmolality. It is concluded that incorporation of nitrite-N in the hemolymph of P. japonicus following exposure to ambient nitrite-N affects its acid-base balance, ammonia excretion, and osmoregulation.     

Occupational dimethylformamide exposure

Summary The relationship between the 8-h time-weighted average (TWA) intensity of exposure toN, N-dimethylformamide (DMF) vapor (with little possibility of skin contact with liquid DMF) and the subsequent excretion ofN-monomethylformamide (MMF) precursor in shift-end urine samples was examined in 116 workers exposed to DMF and 92 workers exposed to DMF in combination with toluene. Urinary MMF level was examined also in 42 non-exposed subjects. The TWA vapor concentration in breathing zone air of each worker was successfully measured by means of a recently developed diffusive sampler in which water was used as an absorbent. The examination of gas chromatographic (GC) conditions for MMF determination showed that the formation of MMF was not saturated when the injection port temperature was set at 200°C, reached a plateau at 250°C, and showed no additional increase at 300°C. There was a linear relationship between DMF in air and MMF in urine with a regression equation ofy =1.65x + 1.69 (r = 0.723,P<0.01), wherey is MMF (unit; mg/l, uncorrected for urine density) in urine andx is DMF (ppm) in air, when only those exposed to DMF were selected, and the injection port temperature was set at 250°C. From this equation, it was possible to estimate that about 10% of the DMF absorbed will be excreted into urine as the MMF precursor. The slope of the regression line was significantly smaller among those exposed to DMF and toluene in combination as compared with those with DMF exposure only.     

Effects of waterproof covering on hand immersion tests using water at 10°C, 12°C and 15°C for diagnosis of hand–arm vibration syndrome

Objectives: To compare effects of waterproof covering on finger skin temperature (FST) and subjective hand pain during immersion tests using cold water at 10°C, 12°C and 15°C. In the (Draft International Standard) of the International Organization for Standardization (ISO/DIS 14835-1), a water temperature of 12°C and use of water covering are proposed. Methods: Six healthy male subjects took part in the immersion tests and immersed both hands into water at 10°C, 12°C and 15°C for 5 min, repeatedly, with waterproof covering (polyethylene gloves) or without (bare hands). The FST data from middle fingers and subjective pain scores for hand pain were analyzed. Furthermore, the test with water at 12°C was repeated to assess the repeatability of the test. Results: The glove and water temperature factors for FST were significant at every minute from 1 min during immersion up to 2 min after recovery, showing higher values for waterproof covering than for bare hands and showing lowest values for water temperature of 10°C and highest for 15°C. The glove and water temperature factors for subjective pain score were significant at the 1-min and 2-min points during immersion, showing lower scores for waterproof covering than for bare hands and showing highest scores for water temperature of 10°C and lowest for 15°C. The results of the first and second tests using water of 12°C showed no systematic difference in FST and hand pain between the tests, with a few exceptions. Conclusions: Subjective pain during the cold immersion test with polyethylene gloves and water at 12°C can be reduced, while the differences in FST between water temperatures of 10°C and 12°C were small or not apparent at some points during immersion and recovery. The test also seems to be suitable for repeatability. Further investigation on hand–arm vibration syndrome (HAVS) patients to validate the use of the immersion test with gloves to obtain sufficient data for diagnostic value is required.