Needles too:
“San Francisco distributes approximately 400,000 to 4.5 million clean syringes annually through its Department of Public Health and partner organizations, such as the San Francisco AIDS Foundation and Glide Memorial Church.”
A lot of those needles end up in the ocean - and wash up on beaches. I was walking my dogs along a beach in San Francisco after a storm - a city worker told me not to let my dogs root around in the debris b/c it was full of needles - he was using a magnet to try to gather needles that had washed up and showed me a large pile he had collected just that morning.
It is dangerous to do HVAC work due to all the used needles tossed on roofs.