Marine mammals often accumulate high levels of environmental
contaminants,
even those that are globally regulated regarding usage, raising concerns
about their health status. Here, we conducted the first investigation
of tissue distribution, spatiotemporal trends, and potential risks
of six organotin compounds (OTs) in Indo-Pacific humpback dolphins
(n = 101) from the northern South China Sea during
2003–2021. We detected the highest level of hepatic triphenyltin
in these humpback dolphins compared with the results reported in cetaceans
globally, and the liver accumulated the highest OT concentrations
than other analyzed tissues. Despite the downward trend of butyltins
in humpback dolphins after the global ban on the use of OTs as antifouling
paints, levels of phenyltins have continued to increase over the past
20 years, suggesting that the other applications of phenyltins in
South China remain prevalent. In vitro and in vivo analyses revealed
that tissue-relevant doses of OTs could induce agonistic effects on
the dolphin peroxisome proliferator-activated receptor γ as
a master regulator of lipid homeostasis and altered the dolphin fatty
acid profiles. Our results highlight the lipid-disrupting effects
of current OT exposure in humpback dolphins and emphasize the need
for further efforts to eliminate OT contamination in South China.