The first-of-its-kind study, published in the journal Environmental Science & Technology Letters, analysed dust particles from air filters in the ISS and found the levels of potentially harmful chemical contaminants in them to be higher than the average values seen in many US and European homes.
“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,” study co-author Stuart Harrad said.
Among the contaminants found in the dust were the known harmful chemicals polycyclic aromatic hydrocarbons (PAH), perfluoroalkyl substances (PFAS) – commonly known as “forever chemicals” – and polychlorinated biphenyls (PCBs).
In the study, scientists assessed material collected in vacuum bags aboard the ISS, which comprise of previously airborne particles, clothing lint, hair and other debris.
Some of the vacuum bags were returned to Earth to analyse this unique spacecraft cabin dust.
In this dust, researchers also found traces of chemicals like polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD), “novel” brominated flame retardants (BFRs) and organophosphate esters (OPEs), some of which are known to lead to cancer.
The potential human health effects of some of these chemicals have previously led to them being banned or limited in use by many governments across the world.
The UNEP Stockholm Convention deems a set of these chemicals, including PCBs, some PFAS, HBCDD, as well as some formulations of PBDEs as persistent organic pollutants (POPs).
“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,” Dr Harrad said.
Scientists suspect commercially available off-the-shelf items such as cameras, MP3 players, tablet computers, medical devices and clothing, which are brought on board for astronauts to use, may be sources of many of these chemicals.
The higher-than-Earth levels of radiation in the space environment may also be breaking down plastic into micro and nanoplastics that become airborne in the microgravity environment, researchers said.
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