I stumbled accidentally upon this:
http://www.seedsofdeception.com/Publ...MSoy/index.cfm

to quote something:

Most Offspring Died When Mother Rats Ate Genetically Engineered Soy
By Jeffrey M. Smith, author of Seeds of Deception

Irina Ermakova, a leading scientist at the Institute of Higher Nervous
Activity and Neurophysiology of the Russian Academy of Sciences (RAS),
added GM soy flour (5-7 grams) to the diet of female rats. Other
females were fed non-GM soy or no soy at all. The experimental diet
began two weeks before the rats conceived and continued through
pregnancy and nursing.

But the real shock came when the rats started dying. Within three
weeks, 25 of the 45 (55.6%) rats from the GM soy group died compared
to only 3 of 33 (9%) from the non-GM soy group and 3 of 44 (6.8%) from
the non-soy controls.
The soy she was testing was Monsanto's Roundup Ready variety. Its DNA
has bacterial genes added that allow the soy plant to survive
applications of Monsanto's "Roundup" brand herbicide. About 85% of the
soy gown in the US is Roundup Ready. Since soy derivatives, including
oil, flour and lecithin, are found in the majority of processed foods
sold in the US, many Americans eat ingredients derived from Roundup
Ready soy everyday.

The FDA does not require any safety tests on genetically modified
foods. If Monsanto or other biotech companies declare their foods
safe, the agency has no further questions. The rationale for this
hands-off position is a sentence in the FDA's 1992 policy that states,
"The agency is not aware of any information showing that foods derived
by these new methods differ from other foods in any meaningful or
uniform way."[1] The statement, it turns out, was deceptive. Documents
made public from a lawsuit years later revealed that the FDA's own
experts agreed that GM foods are different and might lead to hard-to-
detect allergens, toxins, new diseases or nutritional problems. They
had urged their superiors to require long-term safety studies, but
were ignored. The person in charge of FDA policy was, conveniently,
Monsanto's former attorney (and later their vice president). One FDA
microbiologist described the GM food policy as "just a political
document" without scientific basis, and warned that industry would
"not do the tests that they would normally do" since the FDA didn't
require any.[2] He was correct.

There have been less than 20 published, peer-reviewed animal feeding
safety studies and no human clinical trials-in spite of the fact that
millions of people eat GM soy, corn, cotton, or canola daily. There
are no adequate tests on "biochemistry, immunology, tissue pathology,
gut function, liver function and kidney function,"[3] and animal
feeding studies are too short to adequately test for cancer,
reproductive problems, or effects in the next generation. This makes
Ermakova's research particularly significant. It's the first of its
kind.