The unveiling of a new risk factor associated with bladder cancer in Lebanon.

BACKGROUND: No accurate evaluation of smoking and water pollution on bladder cancer has been conducted in the Lebanese population. Our aim is to examine the significance of smoking and one of the main water pollutants Trihalomethanes (THM) on bladder cancer risk. METHODS: Population Attributable Fraction (PAF) was used to quantify the contribution of the risk factors smoking and THMs on bladder cancer in Lebanon. To calculate PAF for each risk factor, we used the proportion of the population exposed and the relative risk for each risk factor. Relative risks for each risk factor were obtained from published meta-analyses. The population at risk values were obtained from a report on chronic disease risk factor surveillance in Lebanon which was conducted by the World Health Organization between 2008 and 2009 and a national study by Semerjian et al. that conducted a multipathway exposure assessment of selected public drinking waters of Lebanon for the risk factors smoking and THMs, respectively. RESULTS: Bladder cancer cases that were the result of smoking in Lebanon among males and females are 33.4 and 18.6%, respectively. Cases attributed to mid-term exposure to THM contamination of drinking water is estimated at 8.6%. CONCLUSION: This paper further highlights the negative impact of smoking on bladder cancer risk and adds an overlooked and often underestimated risk that THMs have on this type of cancer. Thus, it is imperative that a national based study which assesses THM exposure by gender and smoking status be implemented to determine the real risk behind this byproduct.