Occurrence of azo-dyes, plasticizers, and PAH-bound microplastics: an emerging source and sink for hazardous compounds in indoor environments?

Indoor environments act as significant reservoirs for a wide range of potentially harmful substances, with microplastics (MPs) gaining increased attention in recent years. This study offers valuable insights into the role of MPs as both source and sink for hazardous contaminants within indoor environments. The analytical techniques employed encompass micro-Raman spectroscopy and high-resolution mass spectrometry. The results revealed a strong correlation between the levels of MPs with the size of the residential population. The dominant shape, colour and polymer type of MPs were fibre, white/transparent and polyamide, respectively. The risk of exposure to microplastics through ingestion was 22.5 times higher for infants compared to adults. In settlements where inhabitants utilized firewood as supplementary cooking fuel, an interesting observation was made: pyrene, which is a specific type of polycyclic aromatic hydrocarbon (PAH), was observed to be adsorbed by polystyrene (PS) MPs. This finding illustrates the capacity of MPs to serve as reservoirs for PAHs within indoor environments. Furthermore, the observation of PAH absorption onto MPs in households using firewood highlights a previously underexplored interaction between microplastics and pollutants in indoor settings. Organic micro-pollutants like di-ethyl hexyl phthalate (DEHP), monobutyl phthalate (MBP), 1,2-dihydro-2,2,4-trimethylquinoline and benzisothiazolone (BIT) were detected in both dust and MPs. It underscores the potential for organic micro-pollutants to move between settled dust and MPs within indoor settings, emphasizing the need for further research in this area.