Proden plaque off and virbac cat dry food

Hello guys, 

I have two questions please. Has someone used proden plaque off powder for cats for long term (years)...just wondering if it has any short term/long term side effects. Worried about heavy metals and arsenic in it.

Also does anyone have any lab report for virbac cat dry food. I searched cats.com..it has lab report for many brands but not this one.

Thanks in advance for any insights and guidance!