Persistent Organic Contaminants in Dust from the International Space Station

Polybrominated diphenylethers (PBDEs), hexabromocyclododecane(HBCDD), novel brominated flame retardants (NBFRs),organophosphate esters (OPEs), polycyclic aromatic hydrocarbons (PAH),perfluoroalkyl substances (PFAS), and polychlorinated biphenyls (PCBs)were measured in a composite sample of dust from the InternationalSpace Station (ISS). Notwithstanding the unique environment from whichthe dust originated, while concentrations of all target compound classesfrequently exceeded the median values in terrestrial indoor microenvironmentsin the US and western Europe, ISS dust concentrations were generallywithin the terrestrial range. The relative abundance of the threeHBCDD diastereomers is dominated by & gamma;-HBCDD (96.6% & sigma;HBCDD).This matches very closely with the commercial mixture added to materialsand contrasts with the diastereomer distribution observed in mostterrestrial indoor dust samples (in which & gamma;-HBCDD is typically & SIM;60-70% & sigma;HBCDD). This suggests conditions insidethe ISS do not favor the previously reported photolytically mediatedformation in dust of & alpha;-HBCDD. Also of note, the concentrationof perfluorooctanoic acid (PFOA) in ISS dust (3300 ng/g) exceeds themaximum reported (1960 ng/g) in a 2008 survey of dust from US childdaycare centers and homes. This may reflect the widespread use ofwaterproofing treatments in the ISS to prevent microbial growth. Ourfindings can inform future material choices for manned spacecraftsuch as the ISS.

Automated summary

Polybrominated diphenylethers (PBDEs), hexabromocyclododecane (HBCDD), novel brominated flame retardants (NBFRs), organophosphate esters (OPEs), polycyclic aromatic hydrocarbons (PAH), perfluoroalkyl substances (PFAS), and polychlorinated biphenyls (PCBs) were measured in dust samples from the International Space Station (ISS). Despite its unique environment, the concentrations of these compounds in ISS dust were generally within the range observed in terrestrial indoor microenvironments. However, the relative abundance of HBCDD diastereomers in ISS dust differed from terrestrial dust samples, suggesting different formation conditions. Additionally, the concentration of perfluorooctanoic acid (PFOA) in ISS dust exceeded that found in a survey of US childcare centers and homes, possibly due to the use of waterproofing treatments in the ISS.