Risk Assessment of Dermal Exposure to Tris(2-chloroethyl) Phosphate and Tris(1,3-dichloroisopropyl) Phosphate via Contact with Indoor Dust

Dermal uptake from indoor dust—especially within residential and vehicular environments—constitutes a potentially important exposure route. This study aimed to estimate daily intakes (EDIs) via dermal contact of tris(2-chloroethyl) phosphate (TCEP) and tris(1,3-dichloroisopropyl) phosphate (TDCIPP) using the existing dust concentration data from our previous studies that were designed to investigate oral ingestion exposure to such pollutants in indoor dust from residences and private vehicles in Iraq. Non-carcinogenic (non-CR) and carcinogenic risk (CR) assessments using both dermal and oral ingestion pathways were also determined. Under mean exposure conditions, the EDI values via dermal contact for both compounds were highest in toddlers, followed by professional taxi drivers and then adults, with values ranging from 0.011 to 0.215 ng/kg bw/day. For home dust, corresponding values ranged between 0.036 and 1.48 ng/kg bw/day. Dermal exposure was identified as the second most important pathway, contributing 35% and 32% of total TCEP exposure via home dust, while dermal exposure via contact with car dust contributed 18% and 20% of total TDCIPP exposure, for adults and toddlers, respectively. Hazard index (HI) values were orders of magnitude lower than the reference value (<1), suggesting minimal non-CR health risk. While most CR values were below 1 × 10−6, high-end exposure scenarios slightly exceeded the threshold for TDCIPP. This study provides the first comprehensive dermal exposure assessment for TCEP and TDCIPP in Iraq, and emphasises the need to consider dermal exposure in future risk evaluations.