Gap AEH 2: What is the toxicity of lunar dust in the respiratory system? (Closed)
Last Published:  07/31/18 09:30:04 AM (Central)
Responsible Element: Space Human Factors and Habitability (SHFH)
Status: Closed
Closure Rationale
LADTAG Report (finalized February 7, 2014) was accepted by NASA after evaluation by the Medical Policy Review Board and its peer review process. The recommended PEL was adopted in a revised NASA Standard 3001 Vol 2 Revision A in 2014. Supporting studies include:
  1. Scully, R.R., Lam, C-W., James, J.T. 2013. Estimating safe human exposure levels for lunar dust using benchmark dose modeling of data from inhalation studies in rats. Inhalation Toxicology 25(14): 785–793.
  2. Lam, C-W., Scully, R.R., Zhang, Y., Renne, R., Hunter, R., McCluskey, R., Chen, B.T., Castranova, V., Driscoll, K.E., Gardner, D.E., McClellan, R.O., Cooper, B.L., McKay, D.S., Marshall, L., James, J.T. 2013. Toxicity of lunar dust in inhalation-exposed rats. Inhalation Toxicology 25(12): 661–678.
  3. James, J.T., Lam, C-W., Santana, P.A. Scully, R.R. 2013. Estimate of safe human exposure levels for lunar dust based on comparative benchmark dose modeling. Inhalation Toxicology 25(5): 243–256.
  4. Zhang Y, Lam CW, Scully RR, Williams K, Zalesak S, Theriot C, Yeshitla S, Meyers VE, Wu H, James JT. Persistent Expression Changes of Fibrosis Related Genes in the Lung Tissues of Rats Exposed to Lunar Dust Particles (Submitted to Plos One).   http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20140007371.pdf

Description

During the Apollo missions anecdotal evidence of respiratory effects of lunar dust were reported by crewmembers.  However, there is no scientifically defensible data with which to assess the toxicity of inhaled lunar dusts.  The data to be obtained from the studies described below are therefore essential to determining risk criteria and establishing a permissible exposure limit for airborne lunar dust.

Pulmonary toxicity of lunar will be assessed in rodents by intratracheal / intrapharyngeal instillation (ITI / IPI) studies and by inhalation studies.  In the ITI / IPI studies, groups of rodents will be instilled with suspensions of lunar dust and reference dusts (titanium dioxide [TiO2], and quartz). Bronchioalveolar lavage fluids (BALF) will be assayed for biomarkers of toxicity, and lung tissues will be examined microscopically for histopathological lesions.  The results of the instillation studies will provide information on the toxicity of lunar dust relative to reference dusts whose toxicities are known, and for which industrial exposure limits have been established.  The ITI / IPI data will also be useful for guiding the choice of exposure concentrations for the inhalation study in which markers of toxicity in BALF, and histopathology specimens, will be examined.


Epidemiological evidence has established associations between exposure to specific types of mineral dusts and particular pulmonary pathologies. A common pathway by which exposure to mineral dusts leads to pathology involves inflammation and fibrosis.  Reactive oxygen species (ROS) are important mediators of inflammation.  Therefore cellular toxicity of activated and passivated lunar dusts will be evaluated in studies that examine the ability of the respirable size particles to induce formation and release of ROS by cells of the respiratory system and to affect secretion of mediators of inflammation, such as interleukins 6 and 8 and Tumor Necrosis Factor Alpha, by cultured lung cells. Various assays of cell viability will also be utilized.



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Mappings
Risk Risk of Adverse Health & Performance Effects of Celestial Dust Exposure
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