We’re delighted to announce that we’ve launched the new EpiAirway™ test for inhalation toxicity, as part of the ongoing expansion of our portfolio of animal-free safety tests.
Ensuring product safety for consumers and workers
Inhalation toxicity is an important part of safety assessment for a wide variety of volatile chemical ingredients, from fragrance ingredients for cosmetics through to volatile adhesives, fuels and other industrial chemicals, environmental pollutants, tobacco smoke, e-cigarette products and nanoparticles. The airways and lungs are continuously exposed to a wide array of these gases, vapours and aerosols in everyday life, and exposure can lead to symptoms ranging from mild respiratory discomfort to acute airway / lung injury and even death. Inhalation toxicity is therefore a critical part of ensuring product safety for consumers as well as occupational health for manufacturing workers.
What is EpiAirway™?
EpiAirway™ is an exciting model made from human bronchial and tracheal cells to reconstruct the airway epithelium, closely mimicking the human airway in terms of both structure and function. Remarkably, the reconstructed tissue even includes beating cilia at the epithelial surface, and is able to produce mucus, providing a fantastic simulation of “real-life” airway tissue. The model has been extensively used as a research tool and over 100 peer-reviewed papers have been published to date, in addition to widespread use of the inhalation toxicity protocol across a range of industry sectors.
Cross section through EpiAirway™ and the ciliated apical surface of EpiAirway™
Images courtesy of MatTek
How does the test work?
To measure inhalation toxicity, chemicals, ingredients or formulations are dosed onto the surface of the EpiAirway™ model. Where appropriate, a cap is used to prevent excessive evaporation of volatile substances. After exposure for 3 hours in a cell culture incubator, the test item is removed by gentle washing and any damage to the cells is measured by their ability to metabolise a dye (MTT) into a purple product which we measure using a spectrophotometer. Toxicity is determined by calculation of an “IC75” value – the concentration required to reduce the viability of the cells in the EpiAirway™ model to 75% compared with a negative control treated with water. We also incorporate a positive control – formaldehyde – into every test to confirm that the method has performed according to specification. Items with an IC75 value below a threshold are classified as toxic / irritant to the human airway.
A breath of fresh air for inhalation toxicity testing
The assessment of inhalation toxicity has previously depended on animal tests, including OECD Test Guidelines 403 (Acute Inhalation Toxicity) and 436 (Acute Toxic Class Method), in which animals are exposed to high doses of chemical in inhalation chambers until a lethal dose is identified. This method has been widely discredited on both scientific and ethical grounds, and doesn’t model real-life exposure of humans to moderate doses of volatile chemicals.
EpiAirway™ addresses both the scientific and ethical concerns around the animal tests and allows us to assess the impact of relevant doses of chemicals directly on the human airway epithelium. By detecting early damage to cells, it enables us to acquire safety data in a matter of days, not weeks or months. It isn’t a regulatory test but it is a valuable screen. Considered together with other techniques such as computer modelling and available human data on related substances, it provides a way for cosmetic companies to assess volatile ingredients and formulations, such as fragrances, without the use of animals. For other industry sectors, it can help to reduce the number of animal tests required by providing mechanistic, human-relevant safety information at an early stage of product development.