Disposable Face Masks and PBDEs in Aquatic Environments: Co-contamination and Impacts

• Face masks can form co-contamination with BDE-47 in aquatic environments • Biological responses to co-contamination were species- and endpoint-dependent • Machine learning–aided synchrotron FTIR reveals cellular disruptions in microalgae • Co-contamination induces developmental abnormalities in fish early-life stages • Persistent co-contamination may affect aquatic ecosystems and carbon fixation Disposable face masks have emerged as a widespread source of post-COVID contamination in aquatic environments, particularly in coastal and nearshore waters. However, their capacity to interact with co-occurring contaminants has received limited attention. Here, we demonstrate the potential for face masks to form co-contamination with the representative PBDE congener BDE-47 under aquatic conditions and examine the associated biological impacts. Mask-derived debris adsorbed and concentrated BDE-47, and co-exposure altered biological responses relative to single-contaminant exposure, with greater inhibition observed in some species and endpoints. Co-contamination altered microalgal growth and chlorophyll content, with reductions reaching up to 58% and 72%, respectively, across three phytoplankton taxa, and increased developmental abnormalities in Atlantic cod embryos. Machine learning-aided synchrotron FTIR imaging revealed a link between co-exposure and biochemical alterations in microalgal cells. These findings demonstrate that face masks can form co-contamination with PBDEs, representing an emerging aquatic contamination issue with potential ecological impacts on primary producers and food-web dynamics.