Authorities in Hunan province on Saturday denied that children in a rural school were guinea pigs in a US research project on the effects of genetically modified rice.

A research paper involving 68 Chinese primary-school children in the province was published by the American Journal of Clinical Nutrition on Aug 1, with Guangwen Tang at Tufts University in the US named as the lead author.

The unapproved experimental GM rice, widely referred to as "golden rice" and genetically engineered to produce provitamin A, was created by Ingo Potrykus at the Institute of Plant Sciences in the Swiss Federal Institute of Technology and Peter Beyer at the University of Freiburg more than 10 years ago.

Chen Peihou, deputy director of the Hunan Center for Disease Control and Prevention, confirmed that the second author of the paper, listed as Hu Yuming, is a researcher for the center.

"I was aware of the project in Hengyang in 2008, which involved children and was mainly testing for beta-carotene bioavailability and bioconversion to retinol," or vitamin A, Chen said Sunday. "But as far as I know, no GM rice was used, and all the food involved was locally produced."

He also said that Hu was not asked by the journal to sign the paper before its publication.

"In the project, we just provided the site and assistance to the Chinese Center for Disease Control and Prevention, and we have not dealt with any US institution," he added.

According to Chen, Yin Shi'an, listed in the paper as the third author, is with the China CDC.

Wang Lin, information director of the China CDC, declined to comment.

Chen said his center will continue its investigation and contact the journal about the issue.

Andrea Grossman, a public-relations officer for Tufts University's Human Nutrition Research Center on Aging, however, was quoted by Beijing Youth Daily on Saturday as saying that the monthlong research on golden rice was approved by authorities in both countries after an examination by ethics committees.

Feeding trials with human adults in China have also been carried out to measure the effect of fat in the diet, on bioconversion and bioavailability, according to the Golden Rice Project website, the official golden-rice homepage supported by the Rockefeller Foundation.

On Thursday, Greenpeace, the international environmental campaign group, reported the study, backed by the US Department of Agriculture, which involved feeding golden rice to 6- to 8-year-old children in Hunan.

The study, assigned to the Hunan CDC by the China CDC in 2008, selected 68 primary-school children in a school in Hankou township of Hengyang city.

According to the Hunan CDC, the study was listed as on the Program of National Natural Science Foundation of China.

After the discovery was posted on Sina Weibo, a Chinese micro-blogging website, the news received massive attention online.

After an investigation, the publicity department of Hengyang said on Saturday that there had been no such research project on golden rice. It said on its micro blog there was instead a study on the transformation of carotene in vegetables to vitamin A in children's bodies.

According to Chen Peihou, all results were submitted to the China CDC immediately after the experiment ended, and no paper on that has been published within the country.

Worldwide, debates on long-term safety for GM food continues.

In China, the Ministry of Agriculture in 2009 issued biosafety certificates to two strains of pest-resistant genetically modified rice and corn in what was considered a major development in promoting the research and planting of GM crops.

The strains still need registration and production trial - which will take three to five years - before commercial planting could begin, according to the ministry.

The certificates triggered concern among the public and professionals since there is still no consensus on whether GM food is harmful to humans.

As early as 2001, the State Council introduced a regulation to ensure the safety of GM food, with strict provisions of its research, testing, production and marketing.

At present, the only three kinds of GM food crops that have been approved for commercial planting in China are sweet peppers, tomatoes and papayas, Shi Yanquan, an official at the ministry, was quoted as saying by china.com.cn during an online interview in April.

Also, the country has imported other GM crops, including soybean, corn and rape, from overseas market to satisfy domestic need. For instance, China imported more than 50 million tons of GM soybeans in 2011, most of which were processed to edible oil, he said.

"The country has launched strict transgenic safety and quality assessment system to ensure GM food in the market is as safe as conventional food," he added.

Yang Xiaoguang, a researcher at China CDC, was quoted in April as saying: "So far, we have received no report to show any GM food on the market is harmful to human health. GM food that consumers purchase from the market is safe to eat."

Jin Zhu contributed to this story.

Contact the writers at shanjuan@chinadaily.com.cn and jinhaixing@chinadaily.com.cn

(China Daily 09/03/2012 page1)