Scientists of Wageningen University & Research centre 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.
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