Assessment of Daily Exposure to Organophosphate Esters through PM_2.5 Inhalation, Dust Ingestion, and Dermal Contact

Inhalation of airborne fine particulate matter (PM_2.5), dust ingestion, and dermal contact with dust are important pathways for human exposure to different contaminants, such as organophosphate esters (OPE), compounds that are widely used as flame retardants and plasticizers. There are limited studies assessing the extent of the contamination of OPE in indoor airborne PM_2.5. This study offers a novel approach by examining various indoor environments, such as homes, workplaces, and means of transport, where people typically spend their daily lives. The goal is to provide a comprehensive assessment of daily exposure to these pollutants. Both PM_2.5 and dust samples were collected in order to determine the concentration levels of 17 different OPEs. Fifteen OPEs in PM_2.5 and 16 in dust samples were detected. Concentration levels in indoor air ranged from 4.37 to 185 ng/m³ (median 24.4 ng/m³) and from 3.02 to 36.9 μg/g for the dust samples (median 10.2 μg/g). Estimated daily intakes (EDIs) of OPEs were calculated for adults, yielding median values of 3.97 ng/(kg bw × day) for EDI_Inhalation, 5.89 ng/(kg bw × day) for EDI_Dermal, and 1.75 ng/(kg bw × day) for EDI_Ingestion. Such levels lie below human health threshold risk limits, although in some cases they could be only 2 times below the threshold for carcinogenic risk, with a main contribution from tris(2-chloroethyl) phosphate (TCEP). Given this threshold proximity, additional exposure to these chemicals from other pathways, such as food ingestion, gas phase exposure, and/or inhalation of coarser particles (PM_10-2.5), could therefore lead to health limit exceedances.