I was reading up on what can be grown in lead contaminated soils.

With potatoes, it is residual soil on the tubers which is a concern, not the tubers themselves.

Sweet potatoes, however will accumulate lead and so shouldn't be grown.

The difference is that sweet potatoes are root structures, while regular potatoes are underground stem structures.

Lead in soil largely does not pass into the plant's stems from it's roots thanks to a structure called the Casparian Strip, which prevents material passing between cells. The materials which pass readily into the stems are those which the roots have transported through cells.

Now, some lead does make it through. This lead is deposited into the leaves preferentially vs the fruit.

So for minimal lead exposure in lead contaminated soils, only grow fruit/seed crops and wash any produce with detergent to clean off residual soil.

This information is useful because not everyone can just grow on land that wasn't contaminated. Lead contamination is common in cities due to historical use of leaded paint and leaded gas.

Amending soil with compost or building raised beds with clean soils are ways to further minimize the risk of lead getting into garden veggies.

Generally, crops that we consume the roots are those to avoid.

Carrots, radishes, turnips, beets, and sweet potatoes are definitely on the no-go list for lead contaminated soils.

Sunchokes I am still trying to figure out. The edible portion is an underground stem, but the above ground stems are described as accumulating metals enough they can be used to clean soils.

(Harvest the above ground material yearly and bury it in landfill. Over years.)

For anyone local to me, here's a map of lead contamination around the cities. https://twitter.com/brittch/status/1360675862740430851

I'm certain similar maps have been constructed for most cities, but I'm not familiar with where to find them.

I was looking into the subject because my spouse's family's farm has groundwater contaminated with leaded gas, from decades ago. Groundwater used to irrigate would potentially bring up some lead.

The space only produces hay, but we're in talks of putting in fruit trees and such.

Yeah. Sunroot should not be grown for food in lead contaminated soils.

Everything I find is only in the context of bioremediation, cleaning up contaminated soils.

I did just find a paper (Jasiewcz et al, 2002) showing sunchokes accumulate far more lead in their above ground tissues than they do in their tubers. I'm still not comfortable with the tuber accumulation, but this is interesting.