Dr. Ashis Bhattacherjee Professor Department of Mining Engineering, Indian Institute of Technology, Kharagpur, India Dr. Bijay Mihir Kunar Sr. Lecturer Department of Mining Engineering, Indian School of Mines University, Dhanbad, India Dr. Nearkasen Chau Research Director Inserm, Inserm,U669, University Paris-Sud, University Paris Descartes, Maison des Adolescents, 97 Boulevard Port Royal, F Paris, France Role of Working Condition, Behavioural, Lifestyle and Health Related Factors in Underground Coal Miners Injuries: A Case-Control Study 33rd international conference of safety in mines research institute. Wisla, Poland, September 15-18, 2009

Outline of Presentation ► Introduction ► Objective ► Methodology oStudy design oStatistical Analysis ► Case Study Application ► Conclusions

Introduction ► Coal mines safety is a perennial problem as the coal mining industry is associated with high accidents and injuries ► Injuries pose a significant threat to the safety and health of workers of coal mines. ► In the Indian coal mines (about 565 mines), the numbers of fatal and serious injuries for the year 2006 were 141 and 745 respectively (Source: DGMS). ► The fatal injury rates in Indian coal mines during the recent 10- year period revealed that these figures are almost constant and the serious injury rates are showing an increasing trend.

Fatality rates per 1000 persons Employed in Coal and Non Coal Mines In India ( ) Decade Coal mines Non coal mines  The fatality rate per 1000 persons employed in Indian Non-Coal Mines is 0.42 during the period where as for Coal Mines 0.29 respectively in the same year. Source DGMS

Introduction (Contd.) Trend in death rates and serious injury rates in Indian coal mines during ( )

Introduction (Contd.) Several studies revealed the role of individual behaviour, working condition, lifestyle and health related factors in mine injuries Effective preventive measures and research measures require that individuals’ human behavior should be properly addressed to prevent and control injuries. Designing prevention measures needs the knowledge of contributions of working condition, job stress, individual behaviour, lifestyle and health related factors in occupational injuries of coal miners. The technique of injury epidemiology is used in this study to assess these factors.

Objective of the Study To assess the role of :  Poor perception of working condition, poor safety environment and job stress with occupational injuries in underground coal mines.  Individual behaviors namely risk-taking behavior and emotional instability with occupational injuries in underground coal mines.  Lifestyle factors namely smoking habit, regular alcohol consumption, and sleeping habit with occupational injuries in underground coal mines.  Health related factors namely overweight and presence of diseases with occupational injuries in underground coal mines.

Materials and methods Subjects: Male workers, aged 18-60, from two underground coal mines located in the southern part of India which employed 2,376 miners during the period It was a matched case-control study which was conducted on 245 case- control pairs. In total, there were 245 workers with at least one injury during the period ( ) who participated in this study known as cases. The controls were the subjects who did not face any injury during the past five years.

Materials and methods Subjects:  For each case, two controls were randomly selected from the non- injured population of the mines based on matching criteria age and job.  However, for 85 cases two controls were available. But for the other 160 cases two eligible controls were not available, and consequently only one control was selected for every case.  The subjects were chosen mainly from workers category which consisted of drillers, general mazdoors, support-men, multi-skilled group workers, trammer and others.

Study Protocol: ► The recruitment policy included a standardized questionnaire called interviewed questionnaire. ► The interviewed questionnaire was administrated to each worker participated in the study by face to face interview. ► The management of the mine including the occupational physicians of the case-study mines were participated in this study.

Statistical Analysis ► The scores for the behavioral factors were computed by summing the scores on individual items ► Data were analyzed using the conditional logistic regression model

Cases (Faced Injury) Exposed to one or more diseases Not- Exposed to one or more diseases Controls (No Injury) Exposed to one or more diseases Not- Exposed to one or more diseases N= 245 N= 330 N=130 N= 115 N= 97 N= 233 Direction of inquiry Figure: Distributions of the Risk Factor Disease among the Cases and Controls in the Case-control study Design Present Past Population at risk

Table: Description of Two Case Study Mines

Production, employment* and injury statistics of the mines for the two year period ( ) Mine 1 Mine 2 Mine 1 and Mine 2 (Combined) Production (million tons/year) Manpower(underground + above ground) Number of injuries Total Total Total (Combined) Fatal Serious Reportable Minor Total **F.R/YearFatal Serious Reportable Minor Total * excludes office workers ** Frequency rate of injuries per 1000 persons employed per year

Figure: Distribution of injuries based on Severity during two year period (245 injuries in the period ) for the sample mine

Table: Distribution (%) of all the injuries based on job-occupation in the two case study mines during two year period (262 injuries in the period ) 245 pairs: - matching 1:1 for 160 pairs of the Mine-1 and 1: 2 for 85 pairs of the Mine-2. (%)

Table: Description of the variables on the basis of their categories VARIABLES NO. OF NAME CATEGORIES ► Body mass index (kg/m 2 ) 2 Normal weight (< 23), Overweight (≥23 ) ► Current smoker 2 Yes, No ► Presence of diseases 2Yes, No  Alcohol consumption 2 Yes, No ► Sleep disorder 2<6 hrs, ≥ 6 hrs ► Poor working condition 2Low ( ≤22 ), High ( >22 ) ► Poor safety environment 2Low ( ≤15 ), High ( >15 ) ► Risk-taking behavior 2Low ( ≤12 ), High ( >12 ) ► Emotional instability 2Low ( ≤14 ), High ( >14 ) ► Job stress 2Low ( ≤24 ), High ( >24 ) ► INJURY 2INJURY, NO INJURY

Table: Characteristics (%) of the cases (having one occupational injury or more) and of the controls (245 pairs) * Statistically significant at p< 0.05 % in cases (245 cases) % in controls (330 controls) p-value Overweight (bmi ≥23 kg/m 2 ) Regular consumption of alcohol p<0.001 Current smoker Presence of disease p<0.001 Sleep disorders (<6 hrs) p<0.001 Poor perception of working condition p<0.001

Table: Characteristics (%) of the cases (having one occupational injury or more) and of the controls (245 pairs) (Contd.) * Statistically significant at p< 0.05 % in cases (245 cases) % in controls (330 controls) p-value Poor safety environment Risk-taking behavior p<0.001 Emotional instability p<0.001 Job stress p<0.001

Table: Associations of various risk factors with occupational injury (at least one) (160 cases=1:1 and 85 cases=1:2): Crude odds ratio (OR) and adjusted odds ratio and 95% CI.

Conclusions ► Individual behaviour specifically risk-taking behaviour and emotional instability were highly associated with injuries (2.03≤adjusted OR≤7.40). ► Poor perception of working condition and job stress were also highly associated with injuries (2.56≤adjusted OR≤8.54) ► Alcohol use and presence of disease were common and also have marked roles in injuries (3.04≤adjusted OR≤3.56). ► This valuable information would help in implementing preventive programs in which firms, workers, and researchers have to work together in partnership.