Page 38 - Msingi Afrika Magazine Issue 11

WHOLENESS

men living in greater Boston, Mas- laboratory also showed that Round- in terms of exposure levels for ag-
sachusetts in the United States, not up exposure damages testosterone ricultural workers and members of
connected with studies on infertility producing Leydig cells from mature the general public close to or within
but with aging in general, as consid- rat testis at concentrations a tenth the spraying range [8].
erable loss of serum testosterone is of agricultural use and beginning 1
thought to be a mark of male aging. hour after exposure [7]. Within 24- The researchers found that brief
48 h, the same formulation was tox- exposure to Roundup at 36 ppm
It is notable that the steep decline ic to other cells inducing cell death, (0.036 g/L) for 30 minutes was
in testosterone levels began just in contrast to glyphosate alone, sufficient to induce oxidative stress
after the introduction of genetically which is only toxic to Sertoli cells (a failure of energy metabolism, see
modified (GM) crops in 1994 with (feeder cells for germ cells). At 48 h, later) and activate multiple stress-re-
concomitant increase in glyphosate Roundup induces apoptosis (pro- sponse pathways leading to cell
herbicides use on glyphosate toler- grammed cell death involving DNA death in the pre-puberty rat testis.
ant GM crops. A comprehensive fragmentation) in germ cells and in
review article has blamed glyphosate Sertoli/germ cells co-culture. At the The team concluded [8]: “Altogeth-
for “most of the diseases and condi- very low, non-toxic concentration of er, the Ca2+-mediated disturbances
tions associated with a Western diet” 1 ppm, both Roundup and glypho- by glyphosate-Roundup in rat testis
including infertility [4], although sate decreased testosterone level by cells around 36 ppm, could contrib-
the precise mode of action, at least 35 %. These experiments expose a ute to the reproductive effects ob-
in the case of infertility, remains major inadequacy in the regulatory served in male agricultural workers
unclear. regime, which still regards POEA exposed to this pesticide at prepu-
in Roundup as an inert adjuvant bertal age.”
Roundup more damaging for which no risk assessment is
than glyphosate required. Detailed mechanisms of
There is already evidence that gly- action identified
phosate is an endocrine disrupting A recent laboratory experiment The team found that Roundup
chemical (see later), but the extent shows that Roundup has direct, increases intracellular Ca2+ con-
of the problem is far greater than acute impacts on the mammalian centration by opening L-type
it appears. Different glyphosate testis at levels of exposure orders -voltage-dependent Ca2+ chan-
formulations vary in toxicity, mainly of magnitude below recommended nels – thereby allowing Ca2+ to
because some of them contain agricultural concentrations. enter the cells - as well as targeting
adjuvants that are either toxic by the endoplasmic reticulum IP3
themselves, or else exert synergis- Acute Roundup exposure at (inositol triphosphate) and ryano-
tic effects with glyphosate. It has very low concentrations kills dine receptors (both Ca2+ release
long been known that Monsanto’s cells in the immature testis channels), leading to Ca2+ release
formulation Roundup, the most The Brazilian research team led and overload within the cells, setting
widely used glyphosate herbicide, is by Ariane Zamoner at the Federal off cell death. The mechanisms
far more damaging than glyphosate University of Santa Catarina in Flo- involved were inferred from ex-
itself (reviewed in [5] Ban GMOs rianópolis, and Federal University of periments with specific inhibitors
Now, I-SIS special report). Rio Grande do Sul in Porto Alegre, that cancelled out the effect of
are well aware of the increased Roundup as well as Ca2+ influx;
Giles-Eric Séralini and colleagues at toxicity of Roundup compared with and confirmed by the increase in
University of Caen in France clearly glyphosate, and were prompted to radioactive tracer 45Ca2+ uptake by
demonstrated that POEA (polye- investigate the effects of Roundup testis incubated with Roundup at 36
thoxylated tallowamine, a major by the high prevalence of reproduc- ppm. These events were prevent-
adjuvant surfactant in Roundup) tive dysfunction among agricultural ed by the antioxidants Trolox and
alone was by far the most cytotoxic workers occupationally exposed ascorbic acid, which counteract the
for several human cell types, at con- to the herbicide. They looked at reactive oxygen species (see below)
centrations a hundredth to ten-thou- concentrations of Roundup 2 to 3 responsible for the oxidative stress.
sandth that of glyphosate itself and orders of magnitude below the 10 Activated protein kinase C, phos-
other formulations without POEA 000 to 20 000 ppm (10-20g/L) used phatidylinositol 3-kinase, and the
[6]. Another study from the same in agriculture, which is quite realistic mitogen-activated protein kinases

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