During our endorsement interview over the fluoride debate, the opposition campaign came under scrutiny for the sceintific beliefs of some of its biggest backers. Nichole Maher of the Northwest Health Foundation, who supports fluoridating Portland's water supply, asks opponents why most of their financial support comes from out of state.

The argument gets a bit knotty at times, especially when the three representatives of the pro-fluoride campaign start interrupting each other.

Portland voters will decide May 21 over Measure 26-151, which would require the city to fluoridate its drinking water.

The participants are, from far left to right, Maher; Dr. Mike Plunkett, a dentist and dental director of Care Oregon; and Dr. Phillip Wu, a pediatrician—all for the pro-fluoride campaign, Healthy Kids, Healthy Portland.

For the opponents, from far right to left, North and Kellie Barnes, a physical therapist, from Clean Water Portland.