now if you sit there trying to get high huffing solder fumes or solder for hours at a time day in and out probably, using it here or there no... Like the others have said if you worried just do it in a well ventilated area.

You might not have noticed but most products contain may cause cancer on it somewhere in teeny tiny print. They do this to cover their asses so they can't be sued if anyone develops cancer while using it. One of my favorite cancer warnings was on a extension cord it said and I kid you not "Product may cause cancer in the the state of California" I was like well glad I don't live in California so I won't get cancer using it