Dechlorane Plus isomers in Andean condors across Chile: spatial patterns and isotopic associations.

Dechlorane Plus (DP), a widely produced chlorinated flame retardant listed under the Stockholm Convention in 2023, raises emerging environmental concerns due to its persistence, bioaccumulation potential, and widespread occurrence. However, its distribution and exposure pathways in terrestrial avian predators, particularly in the Southern Hemisphere, remain poorly documented. Here, we analyzed secondary feathers from Andean condors (Vultur gryphus) collected across a ∼2,500 km latitudinal gradient in Chile for syn-DP and anti-DP isomers and integrated stable isotope (δ13C, δ15N) data. Anti-DP predominated across samples, and geographic variation in ΣDP concentrations was primarily driven by differences in anti-DP, with significantly lower concentrations in the Austral zone than in the Central and Southern regions. DP concentrations were positively associated with δ13C and negatively associated with δ15N across the full dataset; however, these relationships were region-specific, suggesting that isotopic signals of exposure depend on regional ecological and contamination contexts. No age-related differences were detected, indicating that feather DP concentrations are more consistent with feather growth dynamics, depuration processes, and DP toxicokinetics than with progressive lifetime accumulation. These findings provide the first evidence of DP exposure in a Southern Hemisphere scavenging raptor and support the use of Andean condors as sentinels for emerging contaminants, while highlighting the need for further research on DP sources, exposure pathways, and potential toxicological effects in long-lived terrestrial predators.