Pulmonary effects of inhalation exposure to propylene glycol ethers on blood gas diffusion - a human and in vitro study.

BACKGROUND

Propylene glycol ethers (PGEs) are volatile organic compounds commonly used as solvents in occupational and household products, making inhalation exposure ubiquitous. Although some PGEs are upper airway irritants, the underlying pulmonary effects of inhalation exposure to PGEs remain unknown. Darkened blood color was previously observed following human inhalation exposure to PGEs, suggesting reduced blood oxygenation and gas diffusion in the lungs.

METHODS

Pulmonary effects of the most common PGEs, propylene glycol monomethyl ether (PGME) and butyl ether (PGBE), were investigated in healthy participants and in in vitro cultures. Eleven participants were exposed to PGME (35 ppm) and PGBE (15 ppm) for four hours in a whole-body exposure chamber. Variations in alveolar gas diffusion, capillary blood gas, respiratory and heart rates, and inflammation-related blood parameters were tested before, during, and after exposure. PGME and PGBE's effects on alveolar membrane functions, lung inflammation, and cell viability were further assessed in vitro.

FINDINGS: Human exposure to PGME and PGBE showed a decrease in capillary blood oxygenation. Exposures of human alveolar cocultures revealed functional alveolar membrane changes at low PGME/PGBE concentrations. Variations in circulating blood parameters in humans were observed in response to both chemicals, with slightly increased cytotoxicity and inflammation in vitro.

INTERPRETATION: Our results suggest PGEs exposure reduced capillary blood oxygenation in participants, likely via altered alveolar membrane functions. These findings prompt inquiries regarding potential pulmonary effects among individuals routinely exposed to PGEs, particularly in occupational settings, as reported in epidemiological studies.