Intestinal Responses to Benzalkonium Chloride Exposure: Insights from Primary Human Enteroid Monolayers

Abstract

Benzalkonium chlorides (BACs) are cationic surfactants present in hundreds of products, with human exposure rising in recent years. Despite widespread use and unintended ingestion, the direct effects of BACs on the human intestinal epithelium remain understudied. Primary human enteroid monolayers from three independent donors were used to assess transcriptional and barrier responses to acute and chronic BAC exposure. RNA-sequencing revealed that acute 16-hour exposure to a commercially relevant C12/C14/C16 BAC mixture elicited robust transcriptional responses in two of three donors, including coordinated upregulation of cell cycle progression, cholesterol biosynthesis, and xenobiotic metabolism pathways. Substantial inter-donor variability in response magnitude underscores the value of primary human models for capturing individual differences in susceptibility. In contrast, chronic BAC cocktail exposure over 16 days showed minimal transcriptional adaptation and barrier integrity changes, consistent with epithelial adaptation rather than cumulative toxicity. These findings position primary enteroid monolayers as a valuable platform for intestinal toxicology and highlight the need for further characterization of BAC exposure at the site of first oral contact.