Setting up sustainable life support systems for long-term Lunar missions requires the implementation of In-Situ Resource Utilization (ISRU) techniques and the identification of possible substrates, such as Lunar regolith, for different uses and applications. However, the environmental and health compatibility of this substrate needs to be investigated. Literature toxicological data on Lunar regolith simulants (LRS) suggest health hazard if inhaled, however ecotoxicological aspects have not been investigated so far. For this purpose, in this study an ecotoxicological assessment of three commercially available LRS (such as LHS-1D, LHS-2 and LMS-1) with different particle size and composition was performed. The LRS substrates were tested alone and with the addition of a compost (30%), derived from organic fraction of a municipal solid waste for increasing their nutrient content.

The ecotoxicological tests were performed on three model organisms belonging to different trophic levels and environmental compartments such as Aliivibrio fischeri (ISO 11348-3:2019), Lepidium sativum (APAT 2004) and Daphnia magna (ISO 6341:2013). The organisms were exposed to water extracts (UNI EN 12457-2:2004) of each substrate for evaluating their environmental compatibility. Moreover, the Lepidium sativum germination test was also performed exposing seeds to the solid matrices (APAT 2004).

Preliminary results revealed a low acute toxicity of the LRS solid matrices and water extracts, which was generally lowered by the compost presence. Overall data will be discussed considering LRS mineral content and their potential interactions with compost.

This study shows how the ecotoxicological approach can be applied a wide variety of “environmental scenarios”, including extra-terrestrial ones and open new perspectives for a safe use of LRS in future long-term lunar missions, including their application as a substrate for plant growth.