Toxic PCBs detected in deep-sea bivalves

Japanese researchers say they have detected toxic polychlorinated biphenyls, or PCBs, in deep-sea bivalves.

PCBs are manmade chemical compounds that do not easily break down or degrade.

They were created for industrial applications, but most countries have banned their manufacture and use, after they were found to be toxic.

A research group at the Japan Agency for Marine-Earth Science and Technology, or JAMSTEC, examined deep-sea bivalves that belong to the genus Bathymodiolus.

Samples were collected in 2019 at a depth of 1,300 meters in the North Pacific.

The researchers say they detected traces of PCBs, at concentrations of about 40 nanogram per gram.

PCBs have been detected before in deep-sea fish, which are higher in the food chain, and tend to concentrate chemical substances.

But the researchers say this is the first time the toxic compounds have been detected in deep-sea bivalves. They stress the need for further research to determine how extensively deep-sea environments have been contaminated.

Ikuta Tetsuro, leader of the JAMSTEC team, said that PCBs were found in minute quantities that do not pose a threat to humans, but he was surprised that the chemical was present at such depths.

He said it's important to study whether or not PCBs have affected the unique deep-sea ecosystems.