Task Pulmonary Toxicity Studies of Lunar Dust in Mice and Rats (Completed)
Last Published:  07/30/21 01:05:34 PM (Central)
Short Title: Lunar Dust-ITI
Responsible HRP Element: Space Human Factors and Habitability
Collaborating Org(s):
Funding Status: Completed - Task completed and produced a deliverable
Procurement Mechanism(s):
Directed
Aims:
  1. Assess pulmonary toxicity of lunar dust in rodents with Intratracheal and Intrapharyngeal studies.
  2. Assess pulmonary toxicity of lunar dust in rodents via inhalation studies.

Intratracheal instillation (ITI) and intrapharyngeal studies have been completed. Biomarkers measured in bronchial alveolar lavage fluid and blood, and histopathology assessments demonstrated that lunar dust is more toxic than the nuisance dust titanium dioxide but less toxic than the highly toxic quartz dust. The toxicological effects of native respirable particles of lunar dust were not distinguishable from respirable particles produced by grinding of coarse lunar dust with a jet mill or with a ball mill.  An estimate of safe human exposure levels for lunar dust, based upon comparative benchmark dose modeling was published in 2013 (Inhal Toxicol, 2013; 25(5): 243–256).  Results from this study informed the choice of doses to be utilized in inhalation studies

An inhalation study, which utilized two doses of jet mill ground lunar dust to assess dose response was completed in 2011.  Adverse effects were observed in both dose groups.  Therefore, a "no observable adverse effect level" (NOAEL) an important toxicological benchmark, which provides a point of departure for use in establishing a safe exposure level, was not obtained.  A second utilizing two lower doses (the lower an order of magnitude less than the low dose of the first study) was completed and published in 2013 (Inhal Toxicol, 2013; 25(12): 661–678. A NOAEL of 6.8 mg/m3 was successfully achieved in this study and was used to inform development of the permissible exposure limit. 

Integration/Unique Aspects:
Data from these studies will assist in the determination of values of uncertainty factors that will be utilized in establishing a permissible exposure limit for airborne lunar dust.

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