Phthalate esters in dusts from different indoor and outdoor microenvironment and potential human health risk: A case study in Beijing

Phthalate esters (PAEs) are widely used plasticizers that can easily migrate from plastic products, thereby presenting potential health risks through exposure. While PAE concentrations in dust have received increasing attention, there is still a lack of comprehensive understanding regarding their environmental distribution, composition profiles, and associated human exposure risks in Beijing. This study investigated the presence of seven PAEs in 124 dust samples collected from eight indoor and four outdoor microenvironment types across the Beijing metropolitan area. The PAEs were detected universally in all samples, with di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP) and di-iso-butyl phthalate (DIBP) as the predominant compounds, accounting for 91.78%-99.91% and 91.22%-99.76% of total PAE concentrations (E7PAEs) in indoor and outdoor dust, respectively. Indoor dust exhibited significantly higher E7PAEs (range: 45.33-1212.41 mu g/g, mean: 130.61 mu g/g) compared to outdoor dust (range: 2.10-5.41 mu g/g, mean: 3.38 mu g/g). Among indoor microenvironments, taxis had the highest E7PAEs (mean: 1250.59 mu g/g), followed by private cars, print shops, residences, furniture shops, shopping malls, dormitories and offices. Outdoor E7PAEs levels decreased in the order of roads, residential areas, green belts, and parks. Estimated daily exposure doses through dust ingestion were significantly higher than those from dermal absorption and inhalation for five occupational groups (taxi drivers, print shop workers, road workers, office workers, jobless people), indicating dust ingestion as the primary exposure route, with DEHP and DBP as the main contributors. While current exposure levels may not present significant non-cancer risks based on hazard quotient and hazard index estimations, it's noteworthy that DEHP may pose a carcinogenic risk to taxi drivers. Potential risks cannot be overlooked considering the absence of toxicity thresholds, additional exposure pathways, and possible cocktail effects from coexisting pollutants.