I didn't /specifically/ qualify this because if you're gardening in your city backyard, you likely don't have enough acreage to be providing a very substantial

I didn't /specifically/ qualify this because if you're gardening in your city backyard, you likely don't have enough acreage to be providing a very substantial % of your yearly calories via your own garden. Strictly speaking, though, you're right that urban soils have accumulated unpleasantness--so if you're not cash-constrained, maybe container gardening or raised beds is worth it for peace of mind. I haven't personally done research on which plants uptake heavy metals in which amounts, but I'm inclined to figure that a summer's worth of tomatoes, even if grown in leaded soil, will still have less lead than I would have gotten had I lived in the leaded gasoline days. Totally fair to want to do your own math, or/especially to insist on container gardening if your family includes pregnancies/toddlers, though. On the topic of pesticides from gardens--in general what is available to homoeowners is not going to have a lot of persistence. (What is available to farmers is not going to have a lot of persistence, either). The places I would be careful of long-lasting pesticide residues are railroad right-of-ways and (depending on your state & power company) around transformer stations.