Are GMO Crops Causing Fertility Problems?
The first genetically modified corn crop was developed in 1996 and despite many controvercial discussions about its safety, until now there hasn’t been a long term study on the effects of including such foods into our diets. But thanks to the work of an Austrian group, a new study, “Biological effects of transgenic maize NK603xMON810 fed in long term reproduction studies in mice” has been published.
Drs. A. Velimirov, C. Binter, and University Prof. Dr. J. Zentek released the results of a new long term reproductive study on GMO fed mice this month. Their aim was to examine the effects of a certain genetically modified corn crop on multi-generational mice as well as a life-term feeding study of the lab mice. The control mice were given identical living arrangements. The only difference in their existence was the introdution of genetically modified corn to one group of mice.
The scientists noted that there was no significant difference in the life-spans or survival rates of the mice, although they did mention a high rate of death due to cancer.
They conducted two studies: one was a study on four generations of mice and the other was a continuous breeding study that included four litters.
The GM fed mice in the generational study had a lower number of pups weaned, had smaller litter sizes and weights at the time of weaning were also lower. There were also a higher number of pup losses in the GM group. These differences were consistent over the generations but not significant.
The scientists determine that, “It might be speculated that not all mice were compromised by the GM feed because of the high genetic variation between the test animals. The effects on litter size and weight became more notable in the 4th generation” (84).
The authors point out that this type of study has not yet been conducted in the field, as scientists have mainly focused on short-term feeding trials. In short, these kinds of studies look for nutritive equivalence to traditional feeds. Overall, there have only been a few studies conducted on the toxicity and long term effects of genetically modified crops on mammals.
The scientists discovered that over time the mice fed genetically modified corn had a steady declined in litter size despite the fact that they were eating an identical diet as the control group in regards to energy and nutrient intakes. In the third and fourth litters there were significantly lower numbers of pups. The genetically modified feed group always had smaller litters then the control group. They also found that the birth weights had declined in the third and fourth litters.
The scientists conclude that, “Lower reproductive performance can be considered as indicator for a dietary effect. It can be speculated, that this effect was caused by a factor beyond nutrient supply” (85).
In addition, they noted that kidney size was affected. GM mice had smaller kidneys than non-GM mice. The scientists state, “Liver and kidneys are central metabolic organs and are important for metabolic and excretory processes and are therefore often regarded as indicator organs for toxic effects. Therefore differences in liver and kidney weights are considered as sensitive risk parameters” (87).
Velimirov et al. conclude that although they did a genome study on the gut tissue of the mice in both groups it was not indicative of anything specific. They did find a high number of deregulated genes in the GM group, pointing to a complex nutrition-host interaction. They also urge more studies to be conducted on additional species of animals.
