A review of potential hazards of deliberately released Bt maize into the environment

Abstract

Some of the maize growers and the seed producers share great aspirations with respect to introducing transgenic maize into Slovenia. The general public opinion, however, is against it. This article was written on the initiative of the Ministry of the Environment that has tendered for a study about the effects of transgenic maize on the environment. It is based on a review of data from literature and international co-operation among the authors and research groups that run trials on transgenic plants. The Bt maize contains a modified gene from a soil born bacteria, Bacillus thuringiensis Berliner, and is capable of synthesising proteins that are toxic to the European corn borer (Ostrinia nubilalis Hübner) (ECB). The article reviews possible harmful effects of the Bt maize on the environment as well as its advantages. The Bt maize is a reliable way for protecting maize against the ECB. Different Bt events, however, differ in their efficiency. The effect of the event Bt 176, after flowering, is not so effective against the second generation ECB, whereas the events Bt 11 and MON 810 are effective throughout the growing season. Yields of the Bt hybrids are higher only after a strong attack of ECB, due to less stalk damage rather than increased yield. The Bt hybrids, like insecticides, are not equally effective against all pests. Due to the price of seed, it can be profitable only when there is a serious attack of the ECB. The Bt toxin can also affect non-targeted organisms. The risk of this is greater during the time when maize is flowering and producing pollen with high concentrations of Bt toxin. As the release of GMO into the environment can be an irreversible process, remediation may be difficult or impossible to carry out. We did not find any data about the persistence of Bt pollen toxicity in the soil or water systems.