I am not aware of any carcinogens in city water or their relative rate of harm compared to unpasteurized milk, so I suspect that is just conjecture.An example of the bacteria that can be found in cows milk: Brucella, Camplyobacter, Listeria, Mycobacterium bovis, Salmonella and shiga toxin producing E. coli., parasites such as Giardia and viruses such as the norovirus.For more reading:http://skep