Spraying weeds with Roundup herbicide kills them. Spraying GM Roundup Ready crops with Roundup fills them up with Roundup. Spraying people and their food with Roundup has been 'proved' safe. But is it?
The main herbicide in question is 'glyphosate', the active ingredient of 'Roundup' which most GM crops, especially soya, have been engineered to withstand.
A study has now been published which details, not only the developmental abnormalities induced by glyphosate, but the nature of the early tissue disruption involved, and the actual biochemical interference which distorts the tissue growth.
Argentinean researchers used frog embryos, whose early cellular differentiation into different tissues is very similar to the human embryo and is regulated by very similar mechanisms. Their findings were backed up using chicks which are known to be another good model for the human embryo.
As a healthy embryo elongates, natural chemical gradients are set up along its length so that one end develops into the head and nervous system and the other becomes the tail. The vital chemical in this process is retinoic acid which acts on the cascade of genes involved in organ-formation and tissue stability. Precise adjustment of the level of retinoic acid in different parts of the embryo is vital for normal development. This is achieved by a localised enzyme which destroys retinoic acid and so selectively reduces its presence. The problem with Roundup is that glyphosate interferes with that vital enzyme, and levels of retinoic acid remain high and active in the wrong cells. Embryos exposed to high levels of retinoic acid suffer a failure of brain, craniofacial and eye development leading, for example, to anencephaly.
The quantities of glyphosate required to cause reproducible malformations were tiny: 1/5000 dilution for frog embryos and 1/3,500 for chick embryos. The amount given to the embryos was about one tenth of the EU allowable limit for glyphosate. Allowable limits normally include a safety factor of at least 1/100 below the level at which no harm has been detected. The observed malformations were dependent on the dose (this is a key indicator used to prove toxic effect). Although there are other 'commercially confidential' chemicals in Roundup, added to aid cell penetration and increase the desired toxic effect in weeds and which may exacerbate the problem, the researchers identified glyphosate as the ingredient which is at the basis of the observed harm to animal embryos. Studies have shown that the human placenta is permeable to glyphosate.
The first official report, commissioned by one State Government in Argentina, documented a four-fold increase in both cancers and birth defects in the ten years since Roundup Ready crops were introduced there (2000 to 2009). Besides observations from the villages of South America, other relevant laboratory-based evidence of the danger of Roundup has been trickling out. For example: disruption of the placental enzyme needed to create the necessary endocrine hormone balance (via androgen to oestrogen conversion); impairment of mitochondria (i.e. the cells' energy sources); cell toxicity and death; DNA instability which could lead to cancer.
The authors noted the “paucity of data regarding chronic exposure to sublethal doses (of glyphosate-based herbicides) during embryonic development”, and the preponderance of industry data in safety evaluations. Crucially, tests indicate that chemical measurements of retinoic acid in cells are not sensitive enough to reveal the subtle differences vital to healthy cell function: the use of embryo models as sensitive “biosensors” of the toxicity of industrial pollutants such as Roundup are clearly needed.
The Institute of Science in Society has pointed out that glyphosate binds metal ions, and that this could alter the activity of the many metal-dependent enzymes in any life-form. It comments:
“What is becoming clear is that glyphosate can poison crops, soils, wild life, livestock, human beings and the entire ecosystem in multiple systemic ways, and a global ban is long overdue”.
Roundup Ready plants have been designed to withstand glyphosate because they've been given an artificial enzyme which can take over when the natural glyphosate-sensitive enzyme (vital for protein synthesis) has been knocked out by spraying. This is a clever technical trick. However, it also means that the Roundup Ready plants accumulate the glyphosate sprayed on them. As superweeds spring up beside them, Roundup Ready plants are sprayed with glyphosate (and other more toxic herbicides) at greater concentrations and with greater frequency. The end result can only be increased levels of toxins in your food. As this most recent study shows, current levels of herbicide residues may already be too high for safety due to inadequate test sensitivity.
Glyphosate-rich GM foods have been in the North and South American food chain for some years, with no means in place to identify or monitor those consuming them, especially the unborn. Malformed embryos commonly abort, and tend not to become a statistic. Under these circumstances the level of the problem could be masked for many years.
The vast majority of GM crops being grown today and under development, are Roundup Ready or designed to withstand other herbicides which haven't been adequately tested for their ability to cause birth defects in humans.
(This article is adapted from an article which originally appeared on GM-free Scotland in October 2010. The original article is archived here.)
- Alejandra Paganelli et al., 2010, Glyphosate-Based Herbicides Produce Teratogenic Effects on Vertebrates by Impairing Retinoic Acid Signaling, Chemical Research in Toxicology, published on-line August 9 2010
- Michael Antoniou, et al., GM Soya Sustainable? Responsible? Report 2010
- Mae-Wan Ho, Lab Study Establishes Glyphosate Link to Birth Defects, Institute of Science in Society Report 04.10.10, www.i-sis.org.uk/glyphosateCausesBirthDefects.php