Insecticidal Bt toxins such as those produced in genetically engineered plants can be detrimental to human cells. This is a result of recent research led by researchers at the University of Caen (France). Their experiments showed that toxins produced in, for example, the genetically engineered maize MON810, can significantly impact the viability of human cells. The effects were observed with relatively high concentrations of the toxins, nevertheless there is cause for concern. For the first time, experiments have now shown that they can have an toxic effect to human cells.