Help, Dental Sealant for my 7yr old or not?

My son's school is participating in the Oral Health Program in King County and they've promised my son a popcorn party if every child brings back the release for signed the next day (tomorrow). Wherein I'm being asked to allow my second grader (apparently, this program is only for second graders because presumably they have all just gotten their 6 year molars) to participate in receiving free SEALANTS at absolutely no cost. I can either check yes or no and I've only got a little while before bed to figure this out so my son can help the cl get their popcorn party. I tried looking up what SEALANT is and that's where I got frustrated and started looking for help. Anyone.... Apparently the one that is being used is polyvinyl acetal diethylaminoacetate and when I try to figure out if that's dangerous for my Peter, who's already sensitive (eczema due to food allergies) I just get confused. I'm not a scientist. Oh yeah, and he also grinds his teeth sometimes. Will that plastic be ingested? Are there any contraindications? Is it safe? Is it necessary?