Mortality from cardiovascular diseases and sudden death in ferroalloy plants

Reactive hyperemia and baseline pulse amplitude among smelter workers exposed to fine and ultrafine particles

Objective

Ambient exposure to fine particles is associated with increased cardiovascular morbidity and mortality. Associations between occupational particulate matter (PM) exposure and cardiovascular disease have been studied less. The objective of this study was to examine associations between PM exposure and endothelial function among workers in Norwegian smelters.

Methods

We examined endothelial function with Endo-PAT equipment after a working day (WD) and on a day off (DO) in 59 furnace workers recruited from three metal smelters in Norway. The difference in baseline pulse amplitude (BPA) and reactive hyperemia index (RHI) between the 2 days was analysed in relation to individual exposure to PM < 250 nm (PM₂₅₀) or the respirable aerosol fraction of particles, and adjusted for relevant covariates.

Results

The exposure to PM₂₅₀ ranged from 0.004 to 5.7 mg/m³. The mean BPA was significantly higher on WD relative to DO (772 vs. 535, p = 0.001). This difference was associated with PM concentrations among participants ≥ 34 years, but not among the younger workers. Reactive hyperemia was significantly lower on workdays relative to days off (1.70 vs. 1.84, p = 0.05). This difference was observed only among participants above the age 34. No associations with PM exposure were observed.

Conclusions

PM exposure was associated with higher BPA among participants older than 34 years. BPA reflects microvessel pulsatility. Our results may indicate an age-dependent cardiovascular susceptibility to PM exposure. Endothelial function measured by RHI was reduced on WD among participants 34 years and older, but we found no associations between PM exposure and RHI.

Heat shock proteins and cardiovascular disease

Atherosclerosis is the leading global cause of mortality, morbidity, and disability. Heat shock proteins (HSPs) are a highly conserved family of proteins with diverse functions expressed by all cells exposed to environmental stress. Studies have reported that several HSPs may be potential risk markers of atherosclerosis and related cardiovascular diseases, or may be directly involved in the atherogenic process itself. HSPs are expressed by cells in atherosclerotic plaque and anti-HSP has been reported to be increased in patients with vascular disease. Autoimmune responses may be generated against antigens present within the atherosclerotic plaque, including HSP and may lead to a cycle of ongoing vascular injury. It has been suggested that by inducing a state of tolerance to these antigens, the atherogenic process may be limited and thus provide a potential therapeutic approach. It has been suggested that anti-HSPs are independent predictors of risk of vascular disease. In this review, we summarize the current understanding of HSP in cardiovascular disease and highlight their potential role as diagnostic agents and therapeutic targets.

Hsp110 expression changes in rat primary myocardial cells exposed to heat stress in vitro

We investigated and described the kinetics of heat shock protein (Hsp) 110 expression and distribution in rat primary myocardial cells exposed to heat stress in vitro. After incubation at 37°C for 72 h, myocardial cells were heat stressed at 42°C for 0, 10, 20, 40, 60, 120, 240, 360, and 480 min. Significant increases in aspartate transaminase, lactate dehydrogenase, and creatine kinase enzymatic activities in the myocardial cell culture media were observed during heat stress, suggesting that the integrity of the myocardial cells was altered. Immunocytochemical analysis revealed that the expressed Hsp110 was constitutively localized in the cytoplasm and in the nuclei in small amounts characterized by a granular pattern. Nuclear Hsp110 levels increased significantly after 240 min of heat stress compared with levels in the control. The overall levels of Hsp110 expression increased significantly after 20 min. After 240 min, Hsp110 levels were approximately 1.2-fold higher than those in the control. Increasing levels of hsp110 messenger RNA detected using real-time quantitative polymerase chain reaction were observed after 20 min of heat stress, and the levels peaked with a 10-fold increase after 240 min of heat stress. These results indicate that the expression of Hsp110 in primary myocardial cells in vitro is sensitive to hyperthermic stress and that Hsp110 is involved in the potential acquisition of thermotolerance after heat stress. Therefore, Hsp110 might play a fundamental role in opposing and alleviating heat-induced damage caused by hyperthermic stress in primary myocardial cells.

Morbidity profile of steel pipe production workers

Objective:

To study the different morbid conditions among steel pipe producing workers.

Methods:

The present cross-sectional study has been carried out among the workers of one of the steel pipes and tubes manufacturing factory of Gujarat. Hundred workers from the four major departments of the steel pipe production plant, namely welding, pressing machine, X-ray welding and loading/transportation department were covered. The information regarding demographic, occupational, clinical characteristics and diagnosis were recorded on a pre-designed proforma. Statistical analysis included calculation of percentages and proportions and was carried out using the statistical software Epi Info Version 3.3.2.

Results:

The mean age of the study subjects was found to be 38.7±7.1 years. The mean duration of exposure was found to be 9.0±3.4 years. Forty-four percent of the subjects had an upper respiratory tract infection, as evidenced by symptoms like dry cough, cough with rhinitis and cough with fever. Symptoms suggestive of allergic bronchitis were observed in 12% of the subjects while symptoms suggestive of heat stress such as prickly heat, dehydration, perspiration and pyrexia were observed in 13% of the subjects.

Heat exposure control using non-refrigerated water in Brazilian steel factory workers

To test an economically reasonable method to reduce thermal stress, we performed an alternated intervention-control study on 2 groups of 8 male steel workers performing the same jobs, using 2 l of water at ambient temperature (23.5 degrees C +/- 1.4), poured on the head and hands. Each group participated for 2 d as control and 2 d as intervention during 4 consecutive summer days in Brazil, 5 h per shift per day. Testing was done by: 1) recording of temperature by thermistors placed on the external ear canal through earplug, skin (chest, upper arm, inner thigh, outer calf) and clothes; 2) recording of heart rate; and 3) Wet Bulb Globe Temperature recording. The intervention was held hourly, when body weight and water intake were evaluated. Symptoms and subjective sensations were evaluated in the beginning and at the end of each shift. No differences were observed in external ear canal and skin temperatures. Subjective thermal sensation (p = 0.018), sweat perception (p = 0.043), and tiredness (p = 0.028) presented positive statistically significant results when comparing intervention to control measurements. In conclusion, our results could not provide evidence that the proposed method cools the analyzed temperatures, although the subjective evaluation suggests a decrease in the head skin temperature, which could be a useful comfort measure.

Dyslipidemia in Industrial Workers in Hot Environments

The aim of the study was to follow the rate and manifestation of dyslipidemia in industrial workers exposed to heat. One hundred and two male industrial workers exposed to heat and a control group of 102 male workers were studied. The microclimate components were followed and Wet Bulb Globe Temperature (WBGT) was calculated. The mean WGBT was 35.4 degrees C (28.4-41.7 degrees C) for the studied heat exposed work places. The lipid indices: total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and triacylglycerols were assayed with enzymatic tests. TC/HDL-C ratio was calculated, too. Arterial pressure, anthropometric variables, smoking, alcohol use were followed and no significant differences between the studied groups were found. Significantly higher TC, LDL-C and TC/HDL-C were found with the heat exposed industrial workers. Odds ratio indicated higher risk in heat exposed industrial workers of becoming dyslipidemic [for TC OR = 1.481 (1.097-2.002) and for LDL-C OR = 1.539 (1,123-2.111)]. Regular screening of lipid profile in heat exposed workers is recommended.

Cardiovascular toxicities upon manganese exposure

Manganese (Mn)-induced Parkinsonism has been well documented; however, little attention has been devoted to Mn-induced cardiovascular dysfunction. This review summarizes literature data from both animal and human studies on Mn's effect on cardiovascular function. Clinical and epidemiological evidence suggests that the incidence of abnormal electrocardiogram (ECG) is significantly higher in Mn-exposed workers than that in the control subjects. The main types of abnormal ECG include sinus tachycardia, sinus bradycardia, sinus arrhythmia, sinister megacardia, and ST-T changes. The accelerated heart-beat and shortened P-R interval appear to be more prominent in female exposed workers than in their male counterparts. Mn-exposed workers display a mean diastolic blood pressure that is significantly lower than that of the control subjects, especially in the young and female exposed workers. Animal studies indicate that Mn is capable of quickly accumulating in heart tissue, resulting in acute or subacute cardiovascular disorders, such as acute cardiodepression and hypotension. These toxic outcomes appear to be associated with Mn-induced mitochondrial damage and interaction with the calcium channel in the cardiovascular system.

Manganese depresses rat heart muscle respiration

It has previously been reported that moderately high dietary manganese (Mn) in combination with marginal magnesium (Mg) resulted in ultrastructural damage to heart mitochondria. Manganese may replace Mg in biological functions, including the role of enzyme cofactor. Manganese may accumulate and substitute for Mg during the condition of Mg-deficiency. The objective of the current study was to determine whether high Mn alters heart muscle respiration and Mg-enzyme activity as well as whole body Mn retention under marginal Mg. An additional objective was to determine whether high Mn results in increased oxidative stress. In experiment 1: forty-eight rats were fed a 2 x 3 factorial arrangement of Mn (10, 100, or 1000 mg/kg) and Mg (200 or 500 mg/kg). In experiment 2: thirty-two rats were fed one of four diets in a 2 x 2 factorial arrangement of Mn (10 or 250 mg/kg) and Mg (200 or 500 mg/kg). In experiment 3: thirty-two rats were fed one of four diets in a 2 x 2 factorial arrangement of Mn (10 or 650 mg/kg) and Mg (200 or 500 mg/kg). In experiment 2, high Mn and marginal Mg reduced (P<0.05) oxygen consumption of left ventricle muscle. Marginal Mg, but not Mn, reduced (P<0.05) activity of sarcoplasmic reticulum calcium-ATPase enzyme. Dietary Mg had no affect on (54)Mn kinetics, but high dietary Mn decreased (P<0.01) absorption, retention, and rate of excretion of (54)Mn. Neither cellular stress, measured by Comet assay, nor antioxidant activities were increased by high Mn. A strong interaction (P<0.001) between increasing Mn and adequate Mg on hematology was observed. These results confirm previous research in swine that high Mn alters myocardial integrity as well as function, but not as a result of altered calcium transport or oxidative stress.

Hypertension and chronic exposure to noise

The effects of noise on various cardiovascular parameters are conflicting and uncertain. In the current study, the authors studied 52 workers who were employed in a bedframe factory who were chronically exposed to noise and who had poor hearing. An additional group of 65 workers who had jobs in the light-metal sector and another group of 64 office workers served as two control groups; none of the controls were exposed to noise, and none had hearing defects. Blood pressure was measured for each person in the supine and standing positions, and an electrocardiogram was also performed. Sound-level measurements were taken in the workplaces. Mean systolic and diastolic blood pressures and diastolic blood pressure distributions were significantly higher in the noise-exposed group than in both control groups. Among the three groups, there were significantly different frequencies of hypertension, drops in blood pressure, and electrocardiogram anomalies. Within the group of bedframe workers, those exposed to a personal daily level of exposure (i.e., equivalent continuous noise level for exposure to noise for each individual workers in an 8-hr shift) that exceeded 90 dBA had a higher mean diastolic blood pressure and a higher frequency of diastolic hypertension than workers exposed to a personal daily level of exposure of < 90 dBA. The findings suggested that (a) work performed by the bedframe group had some effects on the cardiovascular system, (b) noise is a cardiovascular risk factor, and (c) cardiovascular effects are relative to intensity and type of exposure. Vascular damage often accompanies auditory damage, but--depending on individual susceptibility--the cardiovascular system can respond in various ways.

Study of cancer incidence among 6363 male workers in four Norwegian ferromanganese and silicomanganese producing plants

OBJECTIVES

Little has been known about the risk of cancer associated with occupational exposure to manganese. The objective of this study was therefore to examine the associations between duration of specific work and cancer incidence among employees in four Norwegian ferromanganese and silicomanganese producing plants.

METHODS

Among men first employed in 1933-91 and with at least 6 months in these plants, the incident cases of cancer during 1953-91 were obtained from The Cancer Registry of Norway. The numbers of various cancers were compared with expected figures calculated from age and calendar time specific rates for Norwegian men during the same period. Internal comparisons of rates were performed with Poisson regression analysis. The final cohort comprised 6363 men.

RESULTS

A total of 607 cases of cancer were observed against 596 cases expected (standardised incidence ratio (SIR) 1.02). Internal comparisons of rates showed a positive trend between the rate of all cancers and duration of furnace work. A slightly weaker trend was also found for duration of blue collar non-furnace work when lags of 25 or 30 years were applied in the analyses. However, several results indicated that the incidence of all cancers among the non-furnace workers decreased during the period of active employment.

CONCLUSIONS

Furnace and non-furnace workers may have exposures that increase the incidence of several cancers. The low incidence of cancer among non-furnace workers during the period of ongoing exposure cannot be explained. As this study cannot identify any causal factors, the role of exposure to manganese remains unclear.