Associations between welding fume exposure and blood hemostatic parameters among workers exposed to welding fumes in confined space in Chonburi, Thailand.

BACKGROUND: Occupational welding fumes contain varieties of toxic metal particles and may affect cardiovascular system like the Particulate Matters (PM). Few studies have focused on the effects of toxic metals on the hemodynamic balance; however, the reporting results were not consistent. This study aimed to investigate the association between toxic metals exposure (Chromium (Cr), Manganese (Mn) and Lead (Pb)) and blood hemostatic parameters status after a 3-week exposure cessation among workers exposed to welding fumes. METHODOLOGY: Structured interviews and biological samplings were conducted for 86 male workers without a history of Anemia and Cardiovascular diseases (CVDs) and working in a confined space to construct crude oil tanks. Metal levels of Cr, Mn and Pb in urine were measured during the working days using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) method. The concentrations of hemostatic proteins in blood (White blood cell counts (WBC), Lymphocytes, Monocyte, Eosinophil, Neutrophil, Hematocrit (Hct) were assessed after a 3 weeks exposure cessation. Workers were divided into groups based on occupation type (welder group and non-welder group), and based on metal levels (high and low exposure groups) for comparison. Linear regression models were used to explore the association between metal exposure and multiple blood hemostatic parameters adjusted for age, Body Mass Index (BMI), and smoking status. RESULTS: Urine Mn and Cr level of the welder group was significantly higher than the non-welder group (Mn: 0.96 VS 0.22 ug/g creatinine, p < 0.001; Cr: 0.63 VS 0.22 ug/g creatinine, p < 0.01). The mean value of Hct in the welder group was 44.58 ± 2.84 vol%, significantly higher than the non-welder group (43.07 ± 3.31 vol%, p = 0.026). The median value of WBC in the high Mn-exposed group (6.93 ± 1.59 X 106 Cell/ml) was significantly lower than the low Mn-exposed group (7.90 ± 2.13 X 106 Cell/ml, p = 0.018). The linear regression analyses showed that there was a significantly negative association between log transformed WBC value and the Mn exposure groups (high and low) after adjusting for age, BMI, and smoking status (ß = - 0.049, p = 0.045), but no significant result was found between WBC and occupation types (welder and non-welder) (p > 0.05). Multiple linear regression analysis also showed positive association between Hct and occupational types (welder and non-welders) (ß = 0.014, p = 0.055). The other hemostatic parameters were not different from controls when divided by occupation type or metal level groups. CONCLUSIONS: Our results showed that welders were exposed to about 3 to 4 times higher Mn and Cr concentrations than non-welders. Moreover, one third of the non-welders were exposed to high-exposure groups of Mn and Cr metals. Regression models revealed a significant association of the WBC counts with the Mn exposure group. Therefore, we infer that Mn exposure may play a significant role on the blood hemostatic parameters of workers in the confined space. Hazard identification for non-welders should also be conducted in the confined space.

Aspects of the epidemiology of suicide in England and Wales.

This paper is concerned with the variations in suicide rates in the 161-171 local authorities in England and Wales during the 11-year period 1961-71. Analysis of the overall secular trends shows that the rates for both males and females reached a peak in 1963 and subsequently declined at a steady rate. Virtually the whole of this reduction is associated with the fall in the number of poisonings by domestic gas. Suicide rates were about 50 per cent higher in males than in females and tended to increase with increasing age and, in general, were higher in the county boroughs than in the (more rural) county authorities. There is a marked variation in terms of geographical area, with the highest rates being reported in the London and South-East Region and the lowest rates in the South-East Wales and Northern Regions. There are also systematic differences between the various conurbations, with the highest rates in London and South-East Lancashire and the lowest in Merseyside and the West Midlands. The variations between individual local authorities are then considered and it is shown that as much as 99 per cent of the total variation can be explained in terms of a small number of variables which represent the general characteristics of the the local authority and the population. The most important of these variables is the proportion of single-person housegolds, which accounts for about three-quarters of the variation in the male suicide rates and more than half of the variation in female suicide rates. The significance of these results is discussed, with particular reference to the effect of the detoxification of the domestic gas supply during the period of study.