Some acute and long-term effects of exposure in welding and thermal-cutting operations in Nigeria

Acute respiratory effects of exposure to stainless steel and mild steel welding fumes

Over the past few years, many studies, including one on our previous work, have examined the chronic effects of fumes from stainless steel (SS) welding on the health of welders. These chronic effects have been related to concentrations of chromium and nickel in SS welding fumes. The present study examined the acute respiratory effects of welding fumes in the workplace by measuring the across-shift changes in a population of 144 SS and mild steel (MS) welders and 223 controls. Manual Metal Arc, Metal Inert Gas, and Tungsten Inert Gas welding processes were studied. Pulmonary function tests were performed at the start (ante, or A) and at the end (post, or P) of the work shift. The study of sensitization to harmful respiratory effects of welding was based on the study of the (P-A)/A ratio (%) of the spirometric variations during the shift. The means of these ratios in the control subjects were used to account for the circadian effect. In SS welders we observed a significant decrease in forced vital capacity (FVC) during the shift. Significant across-shift decrements in forced expiratory volume in 1 second (FEV1) and FVC were related to the SS welding exposure compared with MS welding. Moreover, the across-shift decreases in FEV1, FVC, and peak expiratory flow (PEF) were significantly related to the Manual Metal Arc welding process, compared with Metal Inert Gas techniques (respectively, PEF = -2.7% of baseline values [SD, 11.9] vs 2.0% of baseline values [SD, 7.7] P = 0.04; FVC = -1.5% of baseline values [SD, 4.8] vs 0.2% of baseline values [SD, 4.5] P = 0.05). We also demonstrated the influence of duration of SS welding exposure on the course of lung function during the work shift. After 20 years of SS welding activity, SS welders had more significant across-shift decreases than MS welders with a similar MS exposure duration (respectively, FEV1 = -2.7% of baseline values [SD, 5.9] vs 0.7% of baseline values [SD, 4.2] P = 0.008; PEF = -3.8% of baseline values [SD, 9.6] vs 2.3% of baseline values [SD, 6.5] P = 0.04). We concluded that welding-related lung function responses are seen in SS compared with MS welders and in those with a longer lifetime welding history.

An Indicator for Assessing Respirable Soot Particles in Diesel Exhaust during Occupational Exposures

Both acute and chronic impairments of lung function have been demonstrated in humans after exposure to diesel exhaust. The concentration of soot particles in the diesel exhaust is significantly related to its effects on health. The aim of the present analysis was to study the relationship between the concentration of respirable dust as an indicator of exposure to soot particles in diesel exhaust and a biologic exposure indicator variable, i.e., transient lung function decrease. Daily time-weighted average concentrations of carbon monoxide and nitrogen dioxide amounted to 9 % and 25% of the applicable hygienic limit values. Time-weighted average concentration and the proportion of respirable dust in total dust during a workshift were significantly correlated with across-shift decreases in lung function. In the absence of a suitable measure for total diesel exhaust exposure, the ratio of the proportion of respirable dust in total dust in a workplace may serve as an indicator of the concentration of soot particles in diesel exhaust.

Short-term respiratory function changes in relation to workshift welding fume exposures

The forced vital capacity (FVC), the forced expiratory volume in one second (FEV1) and the transfer factor for the lung (TL) were measured before and after the 8-h work shift in groups of welders and non-welder controls in a shipyard. For each subject, full-shift average concentrations of welding fume constituents were evaluated. On the average, the lung function indices in both groups of welders and controls decreased from morning through afternoon. The welders demonstrated more reduction in the indices than the control group. In general, there was no significant association between the acute changes in the lung function and the daily amount of exposure to welding fume constituents or the welding environmental factors. However, the overall difference of mean diurnal variations in TL between the groups working under different ventilation condition was significant (P < 0.01). On the average, welders who did not use any ventilation system showed maximum reduction in TL value. Acute reduction of FEV1 was positively correlated (P < 0.05) with the levels of iron oxide produced during welding.