Remember that time Matt Damon farmed potatoes on Mars in a mix of soil and poo? In The Martian, that is - not IRL. That we know of, anyway.
Anyway - researchers have shown that actual Martian soil is likely to be toxic to cells, killing them in minutes.
You see the surface of Mars is rendered deadly to cells thanks to a toxic cocktail of UV radiation interacting with chemical compounds in Martian soil called perchlorates. The Scottish team of researchers also suggest that two other components of the Martian surface, iron oxides and hydrogen peroxide, work with the perchlorates to further increase the toxicity.
The findings suggest the surface of Mars is less inhabitable than we previously thought, but on the plus side, it means that bacteria and other biological contaminants from robotic and human exploration missions are unlikely to survive on the red planet.