I do hope you are using IR pills and sterilfilt tips (5 micron filer) or else high grade 0.2 micron filters. With that you should be OK as long as you also practice safe IV methods using a tie off releasing when registered, using alcohol pads to steralize injection point, pushing the plunger nice n slow, keeping pressure once you pull out to clot the blood, and rotating injection sites to prevent build up of scar tissue or worse collapsed vein.
