not sure what you mean by "nontoxic",,,I think alot of things we use are probably toxic,,,glue, etc,,,,

as far as acid free goes, I try and use ALL acid free, simply because you never know WHAT it's going to do,,,,,HOWEVER, I've used some things that are acidic, I'm sure,,,,cardboard, etc,,,many people do, and yes, the most IMPORTANT thing is that it doesn't touch your pictures,,,or that you spray it with archival spray before you use it,,,