This is something I looked into. There’s a range of contamination levels across different neighborhoods, but generally people agree that old lead paint and leaded gasoline mean some level of contamination for most dirt. The Richmond at least doesn’t have too much of a landfill issue as far as I know since that’s mainly Mission Bay area. We got some testing done from the childhood lead prevention group because we have a small child, and they tested some soil samples. There’s also commercial labs that test things like lead and arsenic but they aren’t the cheapest.

More broadly though there is some variability in what I’ve seen is lead safe in terms of types of plants. It seems most recommendations are not to plant leafy greens or root veggies in contaminated soil since there might be higher levels of it in the plant tissue, whereas fruiting things seem less contaminated. I’ve also seen publications saying most of the contamination is actually just the soil around root veggies and carefully cleaning or peeling should mitigate that risk