Surfactant additives in water-based metalworking fluids lead to strong biophysical inhibition of pulmonary surfactant film

Abstract

As a class of very common and important industrial liquid materials, metalworking fluids (MWFs) are easy to be vaporized into the air and cause pulmonary toxic effects. The inhaled MWF aerosols should first interact with the pulmonary surfactant (PS) film that plays an essential role in maintaining the normal respiratory mechanics and pulmonary immunology in a human body. Here, to probe any potential adverse impacts of airborne MWFs on the biophysical and physiological functions of PS film that may help achieve a deep and comprehensive understanding of the pulmonary toxicology of MWFs, a systematic study on the interaction between an animal-derived natural PS (i.e., Calsurf) film and the aerosols of water-based MWFs and their different constituents is conducted using constrained drop surfactometry (CDS) capable of closely simulating normal tidal breathing and lung-related physiological conditions in vitro. It was found that the airborne MWFs can induce strong PS inhibitions once their accumulated amount in the environment attains 0.2 mg/cm³. And their inhibitory effects are demonstrated to mainly originate from the surfactant additives such as polyethylene glycol monooleate (PEGMO) that can desorb PS film from the air/water interface via competitive interfacial adsorption, although it has normally been regarded as an eco-friendly commercial reagent.