title: Ocular toxicity of authentic lunar dust.
abstract: BACKGROUND
  Dust exposure is a well-known occupational hazard for terrestrial workers and astronauts alike and will continue to be a concern as humankind pursues exploration and habitation of objects beyond Earth. Humankind's limited exploration experience with the Apollo Program indicates that exposure to dust will be unavoidable. Therefore, NASA must assess potential toxicity and recommend appropriate mitigation measures to ensure that explorers are adequately protected. Visual acuity is critical during exploration activities and operations aboard spacecraft. Therefore, the present research was performed to ascertain the ocular toxicity of authentic lunar dust.
  
  
  METHODS
  Small (mean particle diameter = 2.9 ± 1.0 μm), reactive lunar dust particles were produced by grinding bulk dust under ultrapure nitrogen conditions. Chemical reactivity and cytotoxicity testing were performed using the commercially available EpiOcularTM assay. Subsequent in vivo Draize testing utilized a larger size fraction of unground lunar dust that is more relevant to ocular exposures (particles <120 μm; median particle diameter = 50.9 ± 19.8 μm).
  
  
  RESULTS
  In vitro testing indicated minimal irritancy potential based on the time required to reduce cell viability by 50% (ET50). Follow-up testing using the Draize standard protocol confirmed that the lunar dust was minimally irritating. Minor irritation of the upper eyelids was noted at the 1-hour observation point, but these effects resolved within 24 hours. In addition, no corneal scratching was observed using fluorescein stain.
  
  
  CONCLUSIONS
  Low-titanium mare lunar dust is minimally irritating to the eyes and is considered a nuisance dust for ocular exposure. No special precautions are recommended to protect against ocular exposures, but fully shielded goggles may be used if dust becomes a nuisance.
authors: Space Toxicology Office, NASA Johnson Space Center, 2101 NASA Parkway, MC: SF23, Houston, TX 77058, USA.
authors: Valerie E
authors: VE
authors: Meyers
authors: Hector D
authors: HD
authors: Garcìa
authors: Kathryn
authors: K
authors: Monds
authors: Bonnie L
authors: BL
authors: Cooper
authors: John T
authors: JT
authors: James
mesh_terms: D000818:Animals; D018480:Astronauts; D019443:Cosmic Dust / Q000009:adverse effects* / Q000032:analysis; D005128:Eye Diseases / Q000139:chemically induced* / Q000175:diagnosis; D006801:Humans; D016081:Moon; D009784:Occupational Diseases / Q000139:chemically induced* / Q000175:diagnosis; D016273:Occupational Exposure / Q000009:adverse effects*; D010316:Particle Size; D011817:Rabbits
chemical_list: D019443:Cosmic Dust