I loathe silicone so I always try to find out if I can use something else (seems it's easy for most "plastic" mfgrs to just recommend silicone, but I find that if you dig around there are alternatives that don't damage various plastics). I had a Marelon fitting to bed and so I contacted Forespar to check whether it had the same vulnerabilities as "plastic" does to polysulfide, polyurethane, etc. (IIUC they leach out the plasticizers and so damage the fittings.) They said no, it was not vulnerable like that, and I could use pretty much whatever caulking I wanted to. I don't think it would be the same for all/other plastics.