How Safe is Your Drinking Water?
Helicobacter pylori has been identified as a causative agent in cancers that are often the subject of mass tort cases such as lymphoma, stomach and colon cancer. Though the route of transmission of helicobacter pylori is unknown it's believed that the infection is acquired early in life through drinking water.
Here's a paper that will be presented at a conference on water and public health to be held in Philadelphia, Pennsylvania this November by the American Public Health Association that discusses how helicobacter pylori might catch a ride on amoebas to infect our water supply. Or if you want to worry about bladder cancer from exposure to arsenic in the water supply then you might find this link of interest. The full program can be found here.
Two other papers you might find of interest on this cancer-causing agent via the public water supply can be found here and here.