Final answer:
Alcohol is the substance used to clean the site before performing routine venipuncture; it is an effective antiseptic that denatures proteins and disrupts microbial cell membranes.
Step-by-step explanation:
To perform routine venipuncture on a patient with no known allergy to antiseptics, you would use alcohol to clean the site. Alcohol, specifically in concentrations of about 70% aqueous solution, such as isopropyl alcohol or ethanol, is commonly used because it denatures proteins and disrupts cell membranes, leading to microbial cell death. It is preferred over other listed substances like hydrogen peroxide, which may inhibit healing and scar tissue formation, and bleach, which is too harsh for tissue and not suitable for venipuncture preparation. Water alone is insufficient for microbial control. An antiseptic like alcohol is suitable for use on tissues for microbial control to prevent infection, compared to substances such as hydrogen peroxide or Betadine (a brand of povidone-iodine), which could have adverse effects or is used in different clinical settings.