Whale baleen to monitor per- and polyfluoroalkyl substances (PFAS) in marine environments

Per- and polyfluoroalkyl substances (PFAS) comprise > 10,000 synthetic compounds that are globally distributed and highly persistent but remain challenging to monitor. Here we assess the utility of baleen-an accreting, keratinaceous tissue that baleen whales use for filter-feeding-to track PFAS dynamics in marine food webs. In six species investigated, PFAS were detected in all baleen tested (n = 18 plates, 220 samples, Σ₁₀PFAS range 0.02 - 60.5 ng/g dry weight), higher than other tissue types besides liver. Three of the species in our dataset had not been tested for PFAS-contamination previously and two of those species-blue whale and North Atlantic right whale-are endangered species internationally. Apparent links were observed between PFAS and life-history events by testing successive subsamples along the growth axis of the baleen plates. These results establish baleen as a viable sample matrix for assessing PFAS contamination in marine ecosystems by enabling multiyear time-series analyses through single-tissue sampling with seasonal resolution.