PORTLAND, Ore. - The city of Portland gets its water from the Bull Run watershed.
It's a beautiful location that represents natural purity. The city doesn't filter the water it sends into homes. But as soon as the water leaves the lower dam, the first of several chemicals is added before gravity pulls the water toward the city.
Portlanders face a decision on May 21 whether to add fluoride to their water. But many interviewed Thursday didn't realize that the city already adds three chemicals to it.
The first chemical is chlorine. Its chemical symbol is Cl. It is used as a disinfectant to kill the bad things in the water.
Aqueous ammonia is represented by NH4OH. It is added to the water to keep the chlorine from evaporating.
The third chemical is NaOH. That's sodium hydroxide. It increases the PH of the water to cut corrosion of plumbing systems. It helps control lead and copper levels at customers' tap.
Each chemical is bad in high doses but deemed safe by the government at the levels put in Portland's water supply and in your body.
Chemicals from drinking water, food and the environment can accumulate in fatty tissues and organs.
New CDC data show that U.S. citizens, on average, have 212 chemicals in their bodies.
Meanwhile, opponents of Portland's fluoridation measure revealed new test results Thursday.
Clean Water Portland paid to have the chemical used in Philomath's fluoridated water system - the same chemical being proposed in Portland - tested by an outside lab.
The lab found the presence of arsenic, chromium and aluminum.
"A 12 percent increase in arsenic above Portland's highest arsenic levels is a significant increase, and it's totally unacceptable," said Kim Kaminski who opposes fluoridation.
Pro-fluoride advocate Dr. Philip Wu, a Kaiser Permanente pediatrician responded saying, "This is just another example of how the opposition keeps misrepresenting science. Many, many studies have shown that when fluoride is diluted in water, there are no detectable impurities."
Read KATU's stories on fluoridation: