Used needle dumped every two minutes
That means nearly half of the 600,000 syringes dispensed by NHS Lothian through the needle exchange programme have never been returned, despite incentives for addicts to do so.
Health chiefs are limited in what they can do to force injecting drug users to dispense of their needles safely.
If they refuse to hand out any more new needles, they risk the addicts sharing syringes, which could lead to increased levels of HIV and hepatitis C.
The number of needles dispensed locally actually dropped by around 60,000 last year, suggesting that the estimated 3200 addicts in the area could be dropping.
Over the years, it has also made a notable impact on the number of new HIV and hepatitis C cases.