GMWatch, 21 June 2016


Claire Robinson reports on a new study that indicates glyphosate herbicides may be endocrine disruptors


Glyphosate herbicide disrupts the development of the uterus of female rats when they are exposed for 7 days after birth, a new study (abstract below) by Argentine researchers shows.

The glyphosate herbicide caused cell proliferation and structural changes in the rats’ uterus. This was in spite of the fact that no signs of chronic or acute toxicity or differences in weight gain were seen in treated pups.

Glyphosate herbicide also disrupted the expression of proteins involved in uterine development.

The authors conclude that exposure to glyphosate herbicide may affect female fertility and/or promote the development of uterine cancer.

They also state that their study is the first to show endocrine-disrupting effects of a glyphosate-based herbicide on the uterus of newborn and prepubertal rats, supporting the possibility that glyphosate-based herbicides might be endocrine disruptors.

Miscarriages in GM soy-growing regions

Doctors and scientists have noted high rates of miscarriage – sometimes called “spontaneous abortion” – in women living in regions of Argentina where GM Roundup Ready soy is grown and sprayed with glyphosate herbicides. The new study may shed light on this phenomenon.

Dose found toxic in new study is claimed safe by US regulators

The dose of herbicide found to disrupt uterine development in the rats was 2 mg per kg of bodyweight per day, based on the US “reference dose” of pure glyphosate that regulators deem safe to consume every day of our lives for a lifetime.

Clearly, this study questions that assumption of safety.

But there is a complication – namely that the exposure route chosen by the researchers was injection under the skin rather than oral administration.

Oral administration is one of the exposure routes favoured by the Organisation for Economic Cooperation and Development (OECD) for toxicology tests conducted on pesticides for regulatory purposes. Exposure routes are supposed to reflect human exposure routes as closely as possible. Studies that use injection are generally dismissed by regulators as “not relevant” to human risk assessment.

However, the authors point out in their study that given the very early stage of development of the rat pups tested – they would still have been feeding from the mothers – injection was the only exposure route that would ensure incorporation of the whole substance into the rats’ bodies. This makes good scientific sense, but almost guarantees that regulators will try to ignore the study.


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