Is Mastic sealent safe??

I’m buying AC Infinity filter box to place infront of ERV to save on filters. Reviews are the box is not fully sealed when prople flashed light it goes through.
is it safe to use mastic sealent to seal it inside? Is it safe for us to breathe since air will be passing through it?
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Replies
I would use regular foil tape to seal it up. You can also use acrylic duct seal mastic (the one in a pail you brush on) just stay away from anything petroleum based such as acoustic sealant.