Scientists of Wageningen University & Research centre [in The Netherlands] are working on growing crops on Mars and moon soil simulants. Just like the real Martian and moon soil these contain heavy metals in almost the same quantities. Four of the crops grown were tested for heavy metal content. No concentrations were detected that would be dangerous for human health. The four crops are therefore safe to eat and, for some heavy metals, the concentrations were even lower than in the crops grown in potting soil.
Earlier research of the Wageningen scientists had already demonstrated that crops are able to grow quite well on Mars and moon soil simulant if organic matter is added to the soils. Heavy metals such as lead, cadmium and copper are known to be present in the soils. If they are taken up in the parts of the crops that may be eaten, they can make the vegetables inedible for humans.
“For radish, pea, rye and tomato we did a preliminary analysis and the results are very promising,” says ecologist Wieger Wamelink. “We can eat them and I am very curious as to how the tomatoes will taste. Unfortunately, we have not been able to test all ten crops yet, which is why we set up a crowdfunding campaign through which people can feel a genuine participation in this research. Donors will receive a variety of potential gifts of which my personal favourite is a dinner based on the harvest that will include potatoes grown on Mars soil simulant.” [More at link]