An environmental group will open a center Saturday that will provide support for victims of a widespread poisoning episode in 1968 involving contaminated rice-bran oil and will seek to have the incident categorized as one of dioxin pollution, a group official said Wednesday.

The Stop Dioxin Kanto Network, which has described the poisoning as the nation's biggest case of dioxin pollution, also plans to hold a gathering Saturday to urge the health ministry to review its diagnostic standards for recognizing victims.

"Rice-oil contamination is a problem that concerns the health of all people, rather than just a past incident, as dioxin pollution becomes more serious," said group head Toshikazu Fujiwara.

Tens of thousands of people were affected by contaminated rice-bran oil throughout western Japan. They experienced various symptoms, including severe acne, fatigue, nausea and liver disorders.

Although some 14,000 people filed to be recognized as sufferers of the poisoning, government-commissioned diagnostic groups have only affirmed the status of about 1,870.

Initially the contamination was thought to have been caused by polychlorinated biphenyls, or PCBs.

Later studies have shown, however, that the incident was caused bypolychlorinated dibenzofurans. PCDFs are dioxins created during the production and use of PCBs.

The diagnostic standards set by the Health, Labor and Welfare Ministry remain centered on PCBs, however, prompting criticism that the ministry has failed to acknowledge these latest scientific findings.

The ministry may thus designate PCDFs as another agent behind the mass poisoning, ministry sources said.