Stone crushing units are situated mainly in districts bordering West Bengal, Bihar and Jharkhand and in West Bengal most of them are situated in Bankura, Birbhum, Mindnapore and Purulia districts. This unorganized sector (small scale industry) with very few number of workers deals with crushing of stones to different sizes as per requirement. During the different processes of operation dust is evolved and the evolved dust if contains free silica in higher percentage may lead to silicosis. One of the areas in Birbhum district from where cases had been referred to the District Hospital at Suri for chest illness.
The Chest Physician, Dr. R. Ghosh of the hospital was surprised to know the cases appeared to be suffering from tuberculosis were not being responded to the treatment. Considering the cases to be resistant one different regiment of ATD tried but in vain. On enquiry he could gather that the patients were coming from the area where the stone crushing units are there. He visited the place and approached the Institute of Wetland Management and Ecological Design, Govt. of West Bengal and then to this Centre. Both IWMED and ROHC(E) approached the Dept. of Environment, Govt. of West Bengal for funding for a study to ascertain the cause. The Govt. of West Bengal through State Pollution Control Board released some funds as well as the Director, NIOH, also contributed for conducting the study.
The objectives of the study were a) to assess the working environmental conditions around a crusher unit, b) to evaluate the health status of the workers engaged in these stone crushing units and c) to suggest the remedial measures, if any for this. The environmental monitoring as per Central Pollution Control Board around the crushing units revealed that respirable particulate matter (RPM) and suspended particulate matter (SPM) were a few fold higher than the prescribed limit value applicable to this industry. The increased values were recorded for RPM and non respirable particulate matter (NRPM) during 6 a.m. to 2 p.m. compared to rest times of the day where as the values were found to be reduced during 10 p.m. to 6.30 a.m. The free silica estimation of the settled dust by FTIR method revealed that it is in non-detectable range.
The pulmonary functions tests did not show any significant difference in lung volumes of male subjects. However, in case of females the values were less than the control subjects. The pulmonary function impairment of the subjects has been given in Fig.4. It has been noted that restrictive type of pulmonary function impairments were more in exposed group but the obstructive and combined type of impairments were more in control groups. The restrictive type of impairments is a feature of dust related morbidity involving the lungs.
The radiological picture of the chest x-rays suggested 2.88% of suspected pneumoconiosis and 1.8% of definite pneumoconiosis. Considering the free silica level in non-detectable range, the prevalence rates were on lower side compared to the environmental exposure. Moreover, their duration of exposure was also low. However, the type of pneumoconiosis needs to be ascertained.