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Potentially Harmful Chemicals Found in Dust on International Space Station

A recent study has found that the concentration of harmful chemical compounds in dust collected from air filtration systems on the International Space Station (ISS) exceeds those found in many American homes. The study, published in Environmental Science & Technology Letters, was conducted by researchers from the University of Birmingham and the NASA Glenn Research Center. The findings could guide the design and construction of future spacecraft.

High Levels of Organic Contaminants Found

The scientists analyzed a sample of dust from air filters within the ISS and found levels of organic contaminants higher than the median values found in US and Western European homes. Contaminants found in the “space dust” included polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), “novel” brominated flame retardants (BFRs), organophosphate esters (OPEs), polycyclic aromatic hydrocarbons (PAH), perfluoroalkyl substances (PFAS), and polychlorinated biphenyls (PCBs).

Potential Sources of Contamination

The use of commercially available off-the-shelf items brought on board for the personal use of astronauts, such as cameras, MP3 players, tablet computers, medical devices, and clothing, are potential sources of many of the chemicals detected. PBDE concentrations in the dust sample falling within the range of concentrations detected in US house dust may reflect the use of inorganic FRs like ammonium dihydrogen phosphate to make fabrics and webbing flame retardant.

Implications for Future Space Stations

Co-author Professor Stuart Harrad from the University of Birmingham said, “Our findings have implications for future space stations and habitats, where it may be possible to exclude many contaminant sources by careful material choices in the early stages of design and construction.” While concentrations of organic contaminants discovered in dust from the ISS often exceeded median values found in homes and other indoor environments across the US and Western Europe, levels of these compounds were generally within the range found on earth.

Recirculated Air and Radiation Exposure

Air inside the ISS is constantly recirculated with eight to 10 changes per hour. While CO2 and gaseous trace contaminant removal occurs, the degree to which this removes chemicals like BFRs is unknown. High levels of ionizing radiation can accelerate aging of materials, including breakdown of plastic goods into micro and nanoplastics that become airborne in the microgravity environment. This may cause concentrations and relative abundance of PBDEs, HBCDD, NBFRs, OPEs, PAH, PFAS, and PCBs in ISS dust to differ notably from those in dust from terrestrial indoor microenvironments.

Vacuuming Required for Efficient Filtration

Screens covering the ISS HEPA filters accumulate debris, requiring weekly vacuuming to maintain efficient filtration. Material in ISS vacuum bags comprises previously airborne particles, clothing lint, hair, and other debris generally identified as spacecraft cabin dust. Some vacuum bags were returned to Earth for studies of this unique dust, with a small sample shipped to the University of Birmingham for analysis in the study.

More information: Stuart Harrad et al., Persistent Organic Contaminants in Dust from the International Space Station, Environmental Science & Technology Letters (2023).

Journal information: Environmental Science & Technology Letters

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