Research suggests that the iron oxides and hydrogen peroxide present in the soil on Mars increases the toxicity of perchlorates.[29] The high level of perchlorates found on Mars (0.05 wt %) is concentrated enough that it would be toxic for humans and crops, and could be used for rocket fuel.[30] Studies indicate that low concentrations of aqueous perchlorates inhibit the height, weight, chlorophyll content and oxidizing power of plants. One plant, E. crassipes, seems to have a high tolerance to perchlorates and might be an ideal plant for growing on Mars.[31] Perchlorates can accumulate in the tissue of plants if grown in a contaminated medium.