For planning of supplies and costs it is important for an immunization
unit to know how many times reusable syringes and needles can be used
. A field study found that BCG syringes, which had their rubber seals
replaced once, could be used at least 150 times, and DPT syringes more
than 200 times even when sterilized in tap water with a hardness of 8
8 mg calciumoxyde per liter. Needles could be used 100 times and when
resharpened several times even more.