He emphasized that the filters must be certified, installed properly and changed regularly. Tests in January found Bridgewater had the highest levels of trihalomethanes, at 459.9 parts per billion, an increase from 252 parts per billion recorded in September. Stewiacke recorded a drop from 101 parts per billion to 25.8, the lowest level in the communities studied. Trihalomethane readings can depend on a lot of different factors, including time of year, water acidity and temperature, Mr. Wigmore said. Health Canada says that a person would have to be exposed to high levels of trihalomethanes for 25 years or more to increase the risk of bladder cancer, which is more common in men than women.
Men have about a one per cent chance of developing bladder cancer.
With prolonged exposure to trihalomethanes, the risk increases to 1.3 per cent. Women's risk increases from .25 per cent to .33, Dr. Scott said. Halifax epidemiologist Linda Dodd, who conducted a study on trihalomethanes and stillbirths in Nova Scotia, found that women in areas with high levels of the compound in their water supply also appeared more likely to experience stillbirths. But Dr. Scott said more research needs to be done before a link is proven. Lockeport mayor tells staff not to drink the water To drink or not to drink the water.