With the recent recalls of all-metal and partial metal hip implants due to metal toxicity and implant failure, recipients of the Stryker Rejuvenate could be forced to undergo revision surgery to replace the recalled hip implant device. For the general population, the levels of cobalt and chromium in the bloodstream-from naturally occurring sources—are approximately 0.5 parts per billion. Patients who have been implanted with a device with metal parts could find those levels considerably higher. The generally accepted “danger” level is considered to be anything over 7 parts per billion however many doctors believe that number is much lower—between 2 and 3 parts per billion.