Sanctum Arts used to have an very nice set with Hazmat Suits, it was expensive though. I haven't seen it on his new webstore but you could e-mail him to see if it was still available.

PoserWorld has a Labtech outfit that might work with the addition of a hood and some gloves.

www.poserworld.com/Downloads/David/10474/Labtech.aspx
I'm not sure if you have to be a member to see the linked page.