Forbes: Mapping San Francisco's Human Waste Challenge - 132,562 Cases Reported In The Public Way Since 2008. https://www.forbes.com/sites/adamandrzejewski/2019/04/15/mapping-san-franciscos-human-waste-challenge-132562-case-reports-since-2008/
I worked in San Francisco's Tenderloin some years ago. I learned quickly to pay attention to where I stepped. Feces everywhere. It didn't take long for me to learn the difference between human and dog feces.
Where you have opiates you have turds. It's all part of harm reduction. I think harm reduction is a good idea, however as SF residents are finding out, there's a lot more to it than just being lenient on drug use.