Half the women who responded to a survey of victims of dioxin-contaminated cooking oil in 1968 say they have since suffered disorders in their reproductive organs, a victims' support group said Wednesday.

In one of the nation's worst food poisoning cases, people mainly living in western Japan who consumed rice bran cooking oil produced by Fukuoka-based Kanemi Soko developed skin disorders, deformities and other abnormalities.

The survey results show that the effects of the contamination, which the government generally sees as a closed case, continues today, although further research is necessary to establish a link between dioxin and the victims' conditions.

The survey by the Tokyo-based support group found that 29 of 59, or 49 percent, of female respondents aged between 20 and 80 have had treatment or surgery on their uteri or ovaries.

Five of them suffered uterine fibroids and the others uterine myoma or ovarian cancer.

Also, nine reported thyroid gland abnormalities.

The support group contacted about 150 female victims of the contamination and their children between July and August. Of them, 59 responded to the survey.

Masazumi Harada, a Kumamoto Gakuen University professor who has examined victims of the cooking oil, said the government should launch a thorough investigation, blaming it and the medical community for closing the case.

Government-certified patients currently number about 1,900, while around 14,000 in total were affected by the poisoning.