Combining in silico and in vitro tools for assessing inhalation hazard of sodium dodecyl sulphate aerosols

Lung surfactant is a complex mixture of surface-active phospholipids
and associated proteins present as a thin film at the air-liquid
interface of the fluid lining the alveolar surface. These components
enable effortless breathing by lowering the surface tension to near
zero values to prevent alveolar collapse at the end of expiration. Inhaled
chemicals have the potential to interact with lung surfactant
and inhibit its function. We investigate, using the constrained drop
surfactometer, the effect of sodium dodecyl sulphate (a surfactant
used safely in consumer products), on lung surfactant inhibition.
This cell-free model has previously been used to assess chemicals
where lung surfactant function inhibition was determined by using
a minimum surface tension of 10 mN/m as the pre-determined cutoff
point above which the alveoli in the intact lungs will collapse.
To refine the determination criteria, we have used a mathematical
model developed to measure changes in the viscoelasticity of the
surfactant and to quantify the effect of SDS on surfactant rheology;
the Fourier Mode Dynamic Tensiometry Method. Inhibition
was correlated to the rate of exposure, i.e., the concentration of
SDS multiplied by the infusion rate. This novel method of assessing
the effect of aerosols on lung surfactant function and rheology
could provide additional information for consumer safety risk assessments
when combined with information from the toolbox of
non-animal approaches currently available.