Inhalation Safety

A significant proportion of Unilever’s products are aerosols and sprays which include underarm antiperspirants, hair sprays, and cleaning products. These products can lead to unintentional inhalation exposure during their use and therefore all ingredients require a safety evaluation. Currently, we integrate all appropriate^* existing information on the ingredient (e.g. in vivo historical animal and human data) and exposure information (computational and experimental) relating to the proposed use to arrive at a safety decision. We are also developing a non-animal approach using a combination of in silico exposure modelling to predict likely deposition across the human airway and a detailed understanding of the key events leading to adverse effects in the lungs of humans.

Bioactivity

Assuring the safety of inhalation exposure to ingredients without the use of toxicity data from animals is challenging. For most ingredients, inhalation exposure is so low that the application of the toxicological threshold of concern (TTC) (i.e. an exposure below which there would be no appreciable risk to human health) can be employed in safety assessment.

For new ingredients and potentially higher levels of inhalation exposure, we have been developing a new non-animal capability to assess safety. The respiratory tract is complex and composed of two main regions, the upper airway, characterised by the nasal and bronchial area, and the lower airway (alveolar region) where gas exchange occurs. To cover the potential adverse effects of a new chemical on the entire lung we consider impairment of mucociliary and alveolar clearance, lung fibrosis, and lung surfactant inhibition the key areas to investigate. We have used adverse outcome pathways (AOP) development to design in vitro testing strategies that provide sufficient biological coverage to ensure the safety of a new ingredient. These include state-of-the-art aerosol exposure systems coupled with relevant functional human epithelial airway models, to reproduce more closely the real-life exposure of the human respiratory tract to inhaled ingredients. We are currently evaluating these tools - testing a wide range of benchmarking chemicals and exposure scenarios.