Occurrence and sources of organic contaminants of emerging concern in indoor dust: A global perspective

Organic contaminants of emerging concern (OCECs) in indoor environments are receiving increasing attention due to their widespread occurrence and potential health risks. Indoor dust, as a key medium through which humans are exposed to OCECs, has become a focal point in global environmental health research. This review concentrates on eight representative categories of OCECs found in indoor dust worldwide: per- and polyfluoroalkyl substances (PFAS), alternative halogenated flame retardants (AHFRs), organophosphate esters (OPEs), chlorinated paraffins (CPs), phthalate alternatives (PAEAs), synthetic antioxidants (SAOs), bisphenol A alternatives (BPAAs), and microplastics (MPs). A variety of OCEC classes are widely present in indoor dust worldwide. Many legacy pollutants (long-chain PFAS) persist, while concentrations of replacement chemicals have increased, reflecting changing use patterns. Monitoring has been concentrated in North America (NA), Europe (EU), and Asia (AS), especially China, whereas Africa (AF) and South America (SA) are largely understudied. Contamination also varies by indoor environment: residential dust is typically enriched in CPs, MPs, and PFAS (from household products); offices, with dense electronics and flame-retardant materials, have especially high levels of AHFRs and OPEs; and educational environments present moderate levels of various OCECs but pose unique risks because of high child exposure. Indoor dust globally serves as a reservoir of OCECs, reflecting our material use and regulations. The pervasive contamination highlights the need for expanded monitoring, particularly in undersampled regions and environments. Understanding indoor OCEC sources and distributions is critical for assessing human exposure, especially for vulnerable groups (infants, children, pregnant women), who have greater dust contact.