Phospholipid chlorohydrins as chlorine exposure biomarkers in a large animal model

Chlorine is a toxic industrial chemical that has been used as a chemical weapon in recent armed conflicts. Confirming human exposure to chlorine has proven challenging, and there is currently no established method for analyzing human biomedical samples to unambiguously verify chlorine exposure. In this study, two chlorine-specific biomarkers: palmitoyl-oleoyl phosphatidylglycerol chlorohydrin (POPG-HOCl) and the lipid derivative oleoyl ethanolamide chlorohydrin (OEA-HOCl) are shown in bronchoalveolar lavage fluid (BALF) samples from spontaneously breathing pigs after chlorine exposure. These biomarkers are formed by the chemical reaction of chlorine with unsaturated phospholipids found in the pulmonary surfactant, which is present at the gas-liquid interface within the lung alveoli. Our results strongly suggest that lipid chlorohydrins are promising candidate biomarkers in the development of a verification method for chlorine exposure. The establishment of verified methods capable of confirming the illicit use of toxic industrial chemicals is crucial for upholding the principles of the Chemical Weapons Convention (CWC) and enforcing the ban on chemical weapons. This study represents the first published dataset in BALF revealing chlorine biomarkers detected in a large animal. Furthermore, these biomarkers are distinct in that they originate from molecular chlorine rather than hypochlorous acid.