Inhaled Kathon may induce eosinophilia-mediated disease in the lung.

In 2011, a link between humidifier disinfectants and patients with idiopathic pulmonary fibrosis was identified in Korea, and Kathon was suggested as one of the causative agents. In this study, Kathon induced apoptotic cell death along with membrane damage at 24 h post-exposure. Additionally, on day 14 after a single instillation with Kathon, the total number of pulmonary cells and the levels of TNF-α, IL-5, IL-13, MIP-1α, and MCP-1α clearly increased in the lung of mice. The proportion of natural killer cells and eosinophils were significantly elevated in the spleen and the bloodstream, respectively, and the level of immunoglobulin (Ig) A, but not IgG, IgM, and IgE, dose-dependently increased. Therefore, we suggest that inhaled Kathon may induce eosinophilia-mediated disease in the lung by disrupting homeostasis of pulmonary surfactants. Considering that eosinophilia is closely related to cancer and fibrosis, further studies are needed to understand the relationship between them.