A study has found evidence that the Bt toxins like those in genetically engineered (GE) maize (corn) can damage human cells.  Although the study used high concentrations of the toxin, biotech companies like Monsanto have always insisted that the GE toxins “are supposed to be active only against particular insects and should have no effect on mammals and humans at all.”   [emphasis mine] 

The same study found that a herbicide containing glyphosate, sold under the brand name Roundup, can damage human cells even in “extremely low dosages.”  This result agrees with other studies that found health risks associated with glyphosate.

The lead scientist, Gilles-Eric Séralini of the University of Caen, said, “We were very much surprised by our findings. Until now, it has been thought almost impossible for Bt proteins to be toxic to human cells. Now further investigations have to be conducted to find out how these toxins impact the cells and if combinatorial effects with other compounds in the food and feed chain have to be taken into account. . . . In conclusion, these experiments show that the risks of Bt toxins and of Roundup have been underestimated.”

The Bt toxins and glyphosate are widely used in GE plants.  “Bt proteins only naturally occur in soil bacteria.  By introducing the modied foxin gene into the plants, the structure of the toxins is modified and may athereby cause selectivity to be changed.  The content of the proteins within the plants is highly variable.”  In fact, many GE plants contain several Bt toxins, in part to combat the growing insect and weed resistance.  “For example, SmartStax produces six different Bt toxins and therefore has a higher overall content of the proteins. In addition, it was made tolerant to herbicides. So far, there has been no investigation of the combinatorial effects of these toxins and residues from spraying, or their potential risks for human health, which was considered unlikely. The researchers have now shown that interactivity does occur.”  Bt toxins do damage human cells.  Further studies are needed to determine the extent of the damage and the specific effects on humans.

Sources:

Press Release 2012–CRIIGEN & Testbiotech, Genetically engineered maize: New indication of health risks, Bt protein toxic to human cells
Mesnage R., Clair E., Gress S., Then C., Székács A., Séralini G.-E., Cytotoxicity on human cells of Cry1Ab and Cry1Ac Bt insecticidal toxins alone or with a glyphosate-based herbicide

You might want to read these other Real Food Houston posts:

Glyphosate is already in our food, air, and water: What is it and why should we care?
Monsanto wants glyphosate limit in food to be raised up to 150 times
GMO Crops Fail Again–This Time Its Bt Corn
It’s Not Pretty Behind the Biotech Veil, an Interview with Howard Vlieger