Having been both a Ham (nearly 40 years) and a cop (27 years) I believe Hams transmit WAY more than Public Safety users. And Hams are generally around transmitters more hours for longer periods. I haven't seen study or known of any link to greater illness caused by radios. And I don't think the cops are "lying" or anything like that. But, I do believe they are misinformed. The Union may have a Lawyer or Doctors that are willing to push the issue for other reasons.
The Public Safety business(s) are stressful, long hours, rotating shifts, difficult work conditions, etc.
Likely that is where the medical problems come from.
Not to mention exposure to Meth Labs, burned cars, homes, etc.
Much of the Public Safety work is done in areas where exposure to unknown or underestimated substances is common.
I spent most of my career working with explosives and Haz-Mat.
Early on, we had NO protective equipment (and didn't think we needed it), later I had every piece of protective equipment I needed.
But, the first responders (patrol, fire and EMS) usually had none or didn't use it.
I believe that is where a lot of the illness and later cancers are coming from.