Further study is needed to determine whether the cultivation of genetically modified corn toxic to pests is directly linked to the discovery of toxin antibodies in Filipino farmers.

A Norwegian scientist who reported that 39 farmers in Polomok, South Cotabato may have been affected by Bt corn yesterday said it still has to be determined if there is a link between the time of planting and the production of antibodies against the Bacillus thurigensis (Bt) toxin carried by the Maize.

But Dr. Terje Traavik, a scientist from the Norwegian Institute of Gene Ecology, maintained that his study could be taken as "early warning" for the Philippines to rethink its commercialization of Bt corn.

"The coincidence in time may or may not show a cause and effect relationship between the production of antibodies against Bt toxin and the diseases suffered by farmers. We never insinuated that we have come up with a study of cause and effect," Mr. Traavik yesterday told a press briefing sponsored by the South East Asia Regional Initiatives for Community Empowerment (SEARICE).

Mr. Traavik was commissioned by SEARICE to undertake the study after church workers in Sitio Kalyong said several residents living around a Bt corn field suffered "unusual or abnormal health problems."

Sister Susan Bolanio of the Diocese of Marbel said the health problems occurred during the flowering of the Bt corn plants. "Residents said the odor of the [Bt corn] pollen smelled like chemicals which made them feel dizzy, suffer severe headaches, chest pains and vomiting," Ms. Bolanio said.

Pablo Senon, who planted Bt corn in Polomolok, said he developed diarrhea, headache, and rashes on his face when the Bt corn plants started flowering.

"My face was itchy and it felt like burning. Most of those who planted Bt corn did not develop these symptoms after planting the crop. But like me, they felt the symptoms when the Bt corn plants were flowering," Mr. Senon said in the vernacular.

Mr. Traavik does not discount the possibility that the Polomolok farmers may have had viral infections prior to the time when the Bt corn plants started flowering. 

From the blood samples, the Norwegian scientist found that the farmers developed three antibodies-IgG, IgA and IgM-which indicate the farmers were exposed to an antigen which could possibly be Bt toxin.

Antibodies are proteins produced by the body to protect itself from foreign substances such as bacteria or viruses.

Biotechnologists and microbiologists yesterday criticized Mr. Traavik and said he should undertake further evaluation of his findings.

"Traavik needs to show pertinent scientific data that establish his claims, before making press releases and unduly causing panic to the public," Nina Gloriani Bargaza, professor of Medical Microbiology & Microbial Immunology at the University of the Philippines-Manila, said in a statement.

However, UP toxicologist Romeo Quijano and Mr. Traavik called on the government to conduct regular monitoring of areas where genetically modified crops are planted.

"You will never really know the level of exposure unless you monitor [these areas] regularly," Mr. Traavik.

Monsanto Philippines, Inc., developer of the Bt corn variety YieldGard, has said some 10,000 hectares of farm lands in Regions I and II and in Mindanao have been planted to Bt corn.