Launched for a third time by the Service Employees International Union-United Healthcare Workers West, Prop. 29 would add new rules on dialysis clinics. If approved, dialysis clinics would be required to have a physician, nurse practitioner, or physician assistant on site during all treatment hours, among other requirements. Opponents say Prop. 29 imposes unnecessary requirements and would cause clinics to shut down.  Guest:  Kevin Stark, KQED science senior editor Your support makes KQED podcasts possible. You can show your love by going to https://kqed.org/donate/podcasts.