He's generally ridiculed for his retracted paper of a few years ago, which set out to try and claim that GMO foods could cause cancer in rats. The problem with his paper was that he used a strain of rats almost guaranteed to get cancer if they lived long enough - and he kept them alive for so long it violated ethical humane standards in almost every nation. He was undone because, given that strain of rats, it actually showed that in many cases GMOs kept rats from getting cancer. He left that part out of his PR blitz then, and his most recent one.
Nonetheless, anti-science groups and the corporatons that fund him keep trotting out his pictures of bloated, tumorous rats and have been waiting with bated breath for his latest science-by-press-conference event.
What has he found? Though 100 billion cows have been given feed containing genetically modified ingredients with no difference at all, Dr. Seralini insists he found some animals who were somehow changed. A dozen owned by some guy somewhere.
There is just one problem, but it is kind of a positive. Unlike most of the people who are experts in genetics, I am not going to ridicule Dr. Seralini for being honest when he writes "it was not designed as a scientific experiment" about his recent collection of anecdotes.
That is the most truthful thing he has done in his career. He was previously chided by European scientists for a wacky "study" of GM soy. Then he claimed GMOs were a "pesticide sponge", whatever that is supposed to mean.
By conceding he does not do any science, he deflects a lot of criticism and loses nothing. He can still pay to publish his work, as he did after his 'GMO causes cancer' paper was retracted, and organic food marketing groups will still link to whatever nonsense he spouts, because they don't know the difference between anecdotes and science anyway.