I've also had no issues the two times I used this method to achieve lavender eyebrows. I think it really helps make your cosplay look complete if you've got a wig. And I've had no concerns about safety, Elmer's is probably even safe to ingest (in small amounts) due to it being made to little kids to use. And unless you've run into skin issues making glue fingerprints I wouldn't foresee irritation from this either. And it's definitely not strong enough to pull out your hair or anything.
Radcon-'12 : Akicon-'13 (not returning) : KuroNekoCon-many years ago : Sakuracon-'13, '14, '15, '16 : PAX Prime-'11, '12, '13, '14, '15 : Rainfurrest '15
PAX West 2016, got my tickets baby!