The Mussel Watch Program in the Asia-Pacific region: levels of persistent organic pollutants from 1989 to 2025-a...

The increasing pollution of the environment by anthropogenic xenobiotics poses a significant global threat. Persistent organic pollutants (POPs), including organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs), are of major concern due to their high toxicity, persistence, and capacity for long-range transport and bioaccumulation. Aquatic ecosystems are particularly vulnerable to POP contamination, which can lead to severe ecological degradation and human health risks. The International Mussel Watch program was established to monitor such contaminants in marine environments using bivalve mollusks as sensitive bioindicators. While the program has been active in the Asia-Pacific region (APR) for decades, a comprehensive synthesis of recent data is needed to assess current pollution status and trends. Here, we review recent data on POP levels in bivalves from the APR countries from 1989 to 2025. The major points are the following: (1) Marine ecosystems in the APR remain contaminated by POPs, with OCPs, particularly DDT and its metabolites, being dominant in many areas such as China, Thailand, and Indonesia; (2) PCB contamination is prominent in post-industrial nations like Japan and South Korea, but elevated levels are also found in some developing countries; (3) the qualitative composition of POPs is often dominated by degradation products, indicating historical contamination, though evidence of fresh inputs persists in some locations; (4) temporal trend analysis reveals a general decrease in POP concentrations in several countries, attributed to regulatory measures, yet increasing or stable trends are observed in others, highlighting the need for continued monitoring.