Used Hypodermic Needles Spilled Onto El Sobrante Street
http://sanfrancisco.cbslocal.com/2013/11/05/2000-used-hypodermic-needles-spill-onto-el-sobrante-street/
I wonder if there was a drug party that involved DUmmies. 
My thought is someone involved with handling Hazard matter did not want to pay the huge price to dispose of them, a hospital or large clinic perhaps.
Perhaps some contractor won a bid to remove and have destroyed the toxic matter from a medical facility the cost to collect and destroy figured into the bid. Some of it the needles were taken out at 5 AM and just dumped in the street. The contractor therefor saving the money to have them properly disposed of.
Seen this done with AB removal from Military ships by private contractors. At least 3/4 of the stuff ended up in the woods or city business dumpsters. Temps would come in to remove the stuff from the triple bagging replace in the outer plain green bag and carted off to save the company's thousands of dollars.