GMW: Monsanto's Round-up toxic

[Guest guest]

GMW: Monsanto's Round-up toxic - Weed Killer Adjuvants May

Boost Toxicity

" GM WATCH " <info

Wed, 31 Aug 2005 23:12:32 +0100

 

 

 

 

GM WATCH daily

http://www.gmwatch.org

------

Monsanto's Round-up is toxic:

http://ehpniehs.nih.gov/docs/2005/113-6/ss.html#roun (Environmental

Health Perspectives Volume 113, Number 6, June 2005)

 

Roundup Revelation

Weed Killer Adjuvants May Boost Toxicity

 

Although the glyphosate-based herbicide Roundup is generally thought to

be less toxic to the ecosystem than other pesticides, concerns about

its effects on human reproduction persist. In a study in Ontario, Canada,

exposure of male farmers to glyphosate-based herbicides was associated

with an increase in miscarriage and premature birth in farm families.

Seeking an explanation for these pregnancy-related problems, researchers

at France's Université de Caen investigated the effects of the full

Roundup formulation and glyphosate alone on cultured human placental

cells

[EHP 113:716-720]. The herbicide, they found, killed the cells at

concentrations far below those used in agricultural practice.

Surprisingly,

they also found that Roundup was at least twice as toxic as glyphosate

alone.

 

Virtually all previous testing of Roundup for long-term health damage

has been done on glyphosate rather than on the full herbicide

formulation, of which glyphosate makes up only around 40%. The

remainder consists

of inactive ingredients including adjuvants, chemicals that are added

to improve the performance of the active ingredient. Roundup's main

adjuvant is the surfactant polyethoxylated tallowamine, which helps

glyphosate penetrate plant cells.

 

The Roundup concentration recommended for agricultural use is 1-2% in

water. The authors incubated placental cells with various concentrations

of Roundup (up to 2.0%) or equivalent concentrations of glyphosate. The

viability of the cells was measured after 18, 24, and 48 hours. No one

is sure how Roundup interferes with reproduction, so the team also

tested whether it, like other pesticides, would disrupt the activity of

aromatase (an enzyme that regulates estrogen synthesis) in placental

cells. Aromatase activity was measured after 1 hour and 18 hours.

 

The researchers found that a 2.0% concentration of Roundup and an

equivalent concentration of glyphosate killed 90% of the cultured cells

after 18 hours' incubation. The median lethal dose for Roundup (0.7%) was

nearly half that for glyphosate, meaning Roundup was nearly twice as

toxic as the single chemical alone. Further, the viability of cells

exposed to glyphosate was considerably reduced when even minute

dilutions of

Roundup were added.

 

After an hour's incubation with Roundup, estrogen synthesis in

placental cells (as shown by aromatase activity) was enhanced by about

40%.

After 18 hours, however, synthesis was inhibited, perhaps reflecting an

effect on aromatase gene expression. This effect was not seen with

glyphosate alone.

 

The study showed that the effect of Roundup on cell viability increased

with time and was obtained with concentrations of the formulation 10

times lower than those recommended for agricultural use. Roundup also

disrupted aromatase activity at concentrations 100 times lower than those

used in agriculture. The researchers suspect that the adjuvants used in

Roundup enhance the bioavailability and/or bioaccumulation of

glyphosate.

 

How these findings translate into activity of Roundup in the human body

is hard to say. The French researchers point out that serum proteins

can bind to chemicals and reduce their availability--and therefore their

toxicity--to cells. Nevertheless, the authors conclude that the

demonstrated toxicity of Roundup, even at concentrations below those in

agricultural use, could contribute to some reproduction problems.

 

 

 

 

------------------