In reply to Brannock:
Just a thought : if you see some needles in a public place, please do all you can to dispose of them.
I've seen the chaos created when a 4 year old girl picks one up and stabs herself (it was hidden behind a hand basin in a new flat - fortunately she was fine, but they had to stick a lot more needles in her to make sure/find out).
You might not have created the problem and fair play for pointing it out, but you can fix it. Empty, transparent drinks bottle is ideal to transport it to somewhere safe.
Steve