The following is a response from Dr. Margaret Mellon, a participant in the Boston Review Magazine Forum that was mentioned here.

As a participant in the Boston Review Magazine forum, I take issue with the sweeping statement that all of the participants agreed that the GE crops currently on the market are safe to eat and safe for the environment. My views on both topics are more nuanced.

I agree that GE products currently on the market--overwhelmingly herbicide tolerant (HT) and BT crops--are unlikely to be allergenic or toxic and on that basis are likely safe to consume. But I also believe that there are holes in the risk assessment process that leave some questions unanswered. This month’s issue of Nature Biotechnology has an excellent feature discussing the challenges of food safety testing.

Moreover, it is important to note that each GE product must be individually assessed for food safety and that the safety status of the HTC and BT crops says little about foods that might be introduced in the future. For example, serious attention needs to be paid to the possibility that GE products produced by gene silencing might inadvertently turn off non-target genes in people who consume them.

I disagree strongly with the statement that the BT and HT crops are safe for the environment. Yes, scientists have documented pesticide reductions in pesticide use immediately following the introduction of these crops, which I welcome and applaud. But these benefits exist only until resistance develops to glyphosate or the BT toxins.

Glyphosate-resistant weeds have already arisen across the US and are leading to enormous increases in pesticide use, reversing the early reductions attributable to the HT crops. The biotechnology industry’s response is a new generation of transgenic crops that enable the use of older, more herbicides like 2,4 D and dicamba. Unless U.S. agriculture responds swiftly, we will soon be facing a nightmare scenario of increased pesticide use resulting from resistant weeds. This is not an example of an environmentally beneficial technology.

BT has proven much more durable, in part because strong regulations allowed the government to impose refuge requirements on U.S. farmers. But resistance has already arisen in corn root worms in the Midwest and is leading to increased chemical insecticide use. 

Dr. Margaret Mellon 
Senior Scientist, Food & Environment Program 
Union of Concerned Scientists