In current research, there is no definite causative factor for the development of bladder tumours, but some studies have found that smoking can increase the risk rate of bladder tumours by 3 to 4 times, and the risk is proportional to the duration and frequency of smoking. Other factors such as long-term exposure to industrial chemical products, occupational environmental factors, chemical drug use, chronic infections, water with high arsenic content and hair dye are also relevant.