Retractor waste varies between practices. Instead of using a universal estimate, separate used disposable retractors over a chosen period, count them and weigh them under your safe waste-handling rules.
Build an annual estimate only from your own measurement: scale the measured consumption by the number of actual working periods. Label the result as an estimate and retain the input data.
If you evaluate a reusable option, record the number of pieces purchased and retired as well as related packaging. Do not assume a fixed lifespan; use and retirement follow the current instructions for use.
After a change, repeat the same measurement and compare like-for-like periods. Communicate publicly only a result that matches your data, measurement scope and method.