Inhalation and Dermal Uptake of Particle and Gas-Phase Phthalates—A Human Exposure Study

Phthalates are ubiquitous in indoor environments, which raises concern about their endocrine-disrupting properties. However, studies of human uptake from airborne exposure are limited. We studied the inhalation uptake and dermal uptake by air-to-skin transfer with clean clothing as a barrier of two deuterium-labeled airborne phthalates: particle-phase D 4 -DEHP (di(2-ethylhexyl)phthalate) and gas-phase D 4 -DEP (diethyl phthalate). Sixteen participants, wearing trousers and long-sleeved shirts, were under controlled conditions exposed to airborne phthalates in four exposure scenarios: dermal uptake alone and combined inhalation + dermal uptake of both phthalates. The results showed an average uptake of D 4 -DEHP by inhalation of 0.0014 ± 0.00088 (μg kg -1 bw)/(μg m -3 )/h. No dermal uptake of D 4 -DEHP was observed during the 3 h exposure with clean clothing. The deposited dose of D 4 -DEHP accounted for 26% of the total inhaled D 4 -DEHP mass. For D 4 -DEP, the average uptake by inhalation + dermal was 0.0067 ± 0.0045 and 0.00073 ± 0.00051 (μg kg -1 bw)/(μg m -3 )/h for dermal uptake. Urinary excretion factors of metabolites after inhalation were estimated to 0.69 for D 4 -DEHP and 0.50 for D 4 -DEP. Under the described settings, the main uptake of both phthalates was through inhalation. The results demonstrate the differences in uptake of gas and particles and highlight the importance of considering the deposited dose in particle uptake studies.