High level PCBs found in mongooses near Futenma Air Station

August 20, 2013 Ryukyu Shimpo

A study group from Ehime University and Meio University has discovered high levels of toxic polychlorinated biphenyls (PCBs) in mongooses caught near U.S. military bases such as Futenma Air Station in Ginowan. Levels of PCBs in these mongooses were up to 8.9 times higher than those in other areas of Okinawa.

Researchers in the group commented on the potential danger involved, saying, “The sources of the pollution are unclear, but we believe there are distinct sources of PCB pollution near the U.S. bases. PCBs could have contaminated other creatures and residents living there.” They called for further monitoring, including inside the bases.

Professor Shinsuke Tanabe of the Center for Marine Environmental Studies of Ehime University, and Professor Yutaka Tashiro of Meio University, conducted the survey. In August and September 2008, they found seven mongooses that had been killed on the road, six near Futenma Air Station and one at the Makiminato Service Area (Camp Kinser) in Urasoe.

Tests revealed that all seven mongooses had PCBs and dioxins in their bodies. The researchers found high levels of mono-ortho PCBs, a specific type of PCB with high toxicity similar to dioxins, at a maximum of 890 nanograms and an average of 310 nanograms per gram of liver fat. Normally, less than 100 nanograms of mono-ortho PCBs would be found in creatures in the wild.

Not only is there a large difference in comparison with mongooses living in other areas of Okinawa, but the figure is ten to 100 times higher than cats, wild boars and raccoons on the main islands of Japan.

Because concentrations of other chemicals such as dioxin are at similar levels to those in terrestrial mammals in other areas, the study group hypothesizes that PCBs contaminated the mongooses near their habitat. With the small number found this time, they say it is unclear how the pollution may have affected the mongooses’ ecosystem.

Mono-orthos make up a large proportion of the PCB mixtures Aroclor 1254, Aroclor 1260, Kanechlor 500, Kanechlor 600 and others. Because of this, the study group pointed out that, “PCBs might have leaked out from transformers and capacitors around the U.S. military bases.”

The study group reported this at the Symposium on Environmental Chemistry held in Tokyo at the end of July. Out of consideration for local residents, they have not revealed where they found the mongooses.

The Makiminato Service Area stores electronic devices that include PCBs. According to a former base employee, from the 1960s, there have been cases of the U.S. military disposing of PCBs into water channels in Okinawa without taking proper measures such as purification.

Glossary: polychlorinated biphenyls (PCBs)
A type of organochlorine compound that includes chlorine in its molecules. Because of its high resistance to heat it was widely used in the insulating oil of transformers and capacitors, as well as in plasticizers and paint. Its toxicity and difficulty to decompose in nature resulted in 1970, Japan and most other countries prohibited the production and use of PCBs. Following the ban, the PCBS in transformers and other devices were disposed of improperly, and have gone missing, so the resulting leaks have become a problem for the environment.

(English translation by T&CT, Lima Tokumori and Mark Ealey)

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