Researchers warn of health hazards: Claire Robinson reports
A diet containing GM soy and maize fed to rats for 30, 60, and 90 days caused a wide range of toxic effects, including DNA damage, abnormal sperm, blood changes, and damage to liver, kidney, and testes.
The Egyptian team of researchers concluded (see item 1 below) that "there are health hazards linked to the ingestion of diets containing genetically modified components".
Histopathological examinations of various body tissues were carried out, and marked differences in the tissues of the GM-fed animals were found. The images, with explanations, can be seen in the published study.
This study did not use the non-GM isogenic (genetically the same but without the genetic modification) comparator crops in the control diet. Instead the control diet was based on wheat as the major source of protein. This diet was tested for GMO content and, in contrast with standard laboratory rodent diets, it was found to be GMO-free.
Because the non-GM isogenic comparator crops were not used in the control diet, it is not possible to conclude that the genetic modification was the cause of the toxic effects found. The two diets were said to be nutritionally equivalent, so nutritional differences can be ruled out as the cause of the toxic effects found. However, the effects may have arisen from pesticide residues in the GM crops.
What can be concluded with certainty is that the GM soy and maize-based diet was more toxic than the wheat-based control diet.
Although no animals were followed for longer than 90 days, a subchronic (less than long-term) period, it's worth noting that liver damage was found from the earliest time point of 30 days.
Commenting on other studies that found no adverse effects from the GM diet tested, the authors suggested that this may sometimes be due to short study durations and low proportions of GMOs in the diet. Undoubtedly the failure of many other authors to carry out histopathological examinations (microscopic examinations of tissues) has something to do with it, too. Many damaging effects can only be seen in this way.
Some of the same team of researchers have also published a separate study (item 2 below) which showed that ingested fragments from the CaMV-35S promoter used in many GM crops incorporated into blood, liver, and brain tissues of experimental rats. The implications of this finding are unknown, though the authors cite other papers that hypothesise that the CaMV-35S promoter could reactivate dormant viruses, create new viruses, and cause cancer by causing over-expression of normal genes.
1. Biological impact of feeding rats with a genetically modified-based diet
2. Addressing the issue of horizontal gene transfer from a diet containing genetically modified components into rat tissues
1. Biological impact of feeding rats with a genetically modified-based diet
Hanaa ORABY, Mahrousa KANDIL, Nermeen SHAFFIE, Inas GHALY
Turk J Biol
(2014) 38:1–11
doi:10.3906/biy-1406-61
http://journals.tubitak.gov.tr/havuz/biy-1406-61.pdf
(open access)
Abstract
This work was conducted in the context of post-marketing bio-safety assessment of genetically modified products. It presents a systematic approach based on a chronic toxicity study on Wistar albino rats, with a range of combined parameters including biochemical, histopathological, and cytogenetic to evaluate the negative impact of a genetically modified (GM) diet on animal health. Histopathological and biochemical analysis procedures were performed in the liver, kidney, and testis. Cytogenetic analysis was evaluated in germ cells and the liver. The results revealed that the laboratory diet used in our investigation was proved experimentally, using the PCR assay, to contain genetically modified components without being labeled as such. The results of all parameters evaluated in our investigation were consistent and confirm that the GM diet fed to rats for 30, 60, or 90 days has deleterious histopathological and histochemical impacts. Biochemical alterations in alanine aminotransferase, aspartate aminotransferase, creatinine, uric acid, and malondialdehyde concentrations were also observed. Genotoxicity of the GM diet was also demonstrated in germ cells as increased numbers of cells with chromosomal aberrations and in liver cells as increased ratios of DNA fragmentation. In conclusion, the results of the present work indicate that there are health hazards linked to the ingestion of diets containing genetically modified components.
2. Addressing the issue of horizontal gene transfer from a diet containing genetically modified components into rat tissues
Oraby H. A. S., Kandil M. M. H., Hassan A. A. M., Al-Sharawi H. A.
African Journal of Biotechnology 13(48): 4410–18, 26 Nov 2014
http://www.academicjournals.org/journal/AJB/article-abstract/BE5331948800
Abstract
Genetically modified (GM) food crops are considered to have the potential of providing food security especially in developing countries. Scientists have raised concern over the hazards associated with the consumption of genetically modified organisms (GMOs). One of these hazards, which have great controversy reports, is the possible horizontal gene transfer from GM-food or feed to human or animal tissues. Many researches were conducted to investigate the presence of some transgenic sequences in animal tissues fed on GM crops. Many of the inserted genes in the GM crops are under the control of the promoter of the Cauliflower mosaic virus (CaMVP35S) and produce insecticidal proteins. Health hazards are suggested to accompany the ingestion of this promoter. CaMVP35S can function in a wide range of organisms (plants and animals). It has also been demonstrated that the CaMV-P35S promoter sequence can convert an adjacent tissue- and organ-specific gene promoter into a globally active promoter. The present work was conducted to evaluate the possibility of horizontal gene transfer from a diet containing DNA segments from Cauliflower mosaic virus -35S promoter (CaMVP-35S) to the cells of different organs of rats fed for three months on diets containing genetically modified components. Analysis of the results revealed that: 1) ingested fragments from the CaMV-35S promoter incorporated into blood, liver, and brain tissues of experimental rats, 2) The total mean of transfer of GM target sequences increased significantly by increasing the feeding durations, and 3) The affinity of different transgenic fragments from the ingested GM-diet, to be incorporated into the different tissues of rats varied from one target sequence to the other.