5. Toxic Effects of Martian Dust on Humans

2005: IVA-2
2010: 2C
Priority: Medium

Investigation: Determine the possible toxic effects of martian dust on humans.

Viking Lander-1 shows the differences in sky visibility and before, during, and after a dust storm. Since dust is so prevalent on Mars, it’s important to determine what effects it could have on humans. Image Credit: NASA/JPL-Caltech

Since Mars is such a dry, dusty, windy place, if humans were to visit the surface of Mars it would be impossible to keep everything clean of dust. It would get everywhere – inside the habitat, all over the suits, and into machinery – so it would be essential to find out if martian dust and regolith is toxic to human beings. Some material on Mars may be carcinogenic (known to cause cancer), and other particles might cause lung conditions like silicosis (respiratory disease caused by breathing in silicants). If scientists know what potentially toxic materials exist on the surface of Mars, they could address their effects on humans, and this information could be considered in system design to reduce health risks.

Click on the expanding links below to see the 2005 and 2010 versions of the investigation.

2005 Version of Investigation (old version)

2010 Version of Investigation (current version)

Between 2005 and 2010, the rovers that have been sent to Mars have provided scientists with observations of the properties of Martian dust. The MECA payload on Phoenix (true microscope to determine physical properties, wet chemistry experiments, triboelectric experiments, and long-duration exposures) and instruments on the Mars Exploration Rovers (MER – Spirit and Opportunity) have all contributed to this investigation. While this information has been helpful, none of the instruments sent to Mars thus far have been capable of measuring specific carcinogenic material. These measurements need to be made to get a better idea of how toxic Mars could be.

Below is a list of books and papers that report on these findings.

2005 Version

2. Investigation. Determine the possible toxic effects of Martian dust on humans.
Measurements:
a. For at least one site, assay for chemicals with known toxic effect on humans. Of particular importance are oxidizing species (e.g., CrVI). (May require Mars Sample Return (MSR)).
b. Fully characterize soluble ion distributions, reactions that occur upon humidification and released volatiles from a surface sample and sample of regolith from a depth as large as might be affected by human surface operations.
c. Analyze the shapes of Martian dust grains sufficient to assess their possible impact on human soft tissue (especially eyes and lungs).
d. Determine if Martian regolith elicits a toxic response in an animal species that are surrogates for humans.

Source:
MEPAG (2008), Mars Scientific Goals, Objectives, Investigations, and Priorities: 2008, J.R. Johnson, ed., 37 p. white paper posted September, 2008 by the Mars Exploration Program Analysis Group (MEPAG) at http://mepag.jpl.nasa.gov/reports/index.html.

2010 Version

2C. Investigation. Determine the possible toxic effects of martian dust on humans.

A discussion about the importance of the potential toxic effects of martian surface materials is detailed in the NRC report, “Safe on Mars (2002),” by the Committee on Precursor Measurements Necessary to Support Human Operations on the Surface of Mars. They considered the presence and distribution of CrVI, commonly called “hexavalent cromium,” especially important to understand because it is a strong human carcinogen. None of the past missions to Mars have carried instrumentation capable of measuring this species. Also discussed in the report are other potential cancer causing compounds, many of which are still of concern due to lack of sufficient data. Potential chronic effects like lung injury in the form of silicosis must also be studied in greater detail, preferably with a returned sample. Collection of data related to the measurements listed above was considered of highest priority from a risk perspective because the risk of insufficient data goes directly to the probability of loss of crew (pLOC). In terms of impact on design it was of comparatively less importance given the fact that EVA systems, as well as dust mitigation protocols and design features, would already be significant, driven by other environmental challenges and forward and back contamination protocols. Overall this investigation was seen to be of “medium” priority.

Measurements:
a. Assay for chemicals with known toxic effect on humans. Of particular importance are oxidizing species (e.g., CrVI) associated with dust-sized particles. May require a sample returned to Earth as previous assays haven’t been conclusive enough to retire risk.
b. Fully characterize soluble ion distributions, reactions that occur upon humidification and released volatiles from a surface sample and sample of regolith from a depth as large as might be affected by human surface operations. Previous robotic assays (Phoenix) haven’t been conclusive enough to significantly mitigate this risk.
c. Analyze the shapes of martian dust grains with a grain size distribution (1 to 500 microns) sufficient to assess their possible impact on human soft tissue (especially eyes and lungs).

Source:
MEPAG Goal IV Science Analysis Group (2010). “IV. Goal: Prepare for Human Exploration.”
Proposed replacement text for MEPAG (2008), Mars Scientific Goals, Objectives, Investigations, and Priorities. Submitted 2 August 2010.