Subject: Re: Allergenicity and genetic modification
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Feb 01 1997
Newsgroups: sci.bio.food-Science

You are all getting in a bit of confusion here. A criteria for approval
of a chemical use is (amongst many other things) that both the chemical,
and it's degradation products have reduced to the approved level (which
is vastly lower than the safe level) in the food part of the crop by
harvest with a safety margin on top.

FYI the following from "The Pesticide Manual".

Glyphosate:

1) Acute oral LD50 rats 5600, mice 11,200 mg/kg. This translates at
5000mg/kg as 500gms for a 100kg man, and bear in mind the product
sprayed is 36% so 1500gm of product. That much salt or ethanol would
kill you too.

2) No effect level. Not found since a 2yr study feeding 300mg/kg
(highest rate used) showed no effects.

3) Environmentl Fate:
a) Very rapidly excreted by animals unchanged.
b) Stated as not being metabolised by plants but some evidence that it
   is.
c) Strongly bound (ie immobile) in soil. DT50 60 days by microbial
   action.

Note that on food crops spraying glyphosate is confined to timings where
the food part (eg grain, seed) is past maximum dry matter weight and is
not absorbing anything from the parent plant. Obviously to do so earlier
would result in significant yield loss. It is done primarily to kill the
plant, so that it desiccates rapidly reducing the time to harvest and
the moisture content of the seed.

I take it that you are aware that soya and canola seeds are very well
protected from contact with the chemical by their pods, and wheat by
it's glumes.

--
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"

From: iaotb@inet.uni-c.dk (Torsten Brinch)
Newsgroups: sci.bio.food-science
Subject: Re: Allergenicity and genetic modification
Date: 2 Feb 1997 13:48:48 GMT

Oz wrote:


>You are all getting in a bit of confusion here. A criteria for approval
>of a chemical use is (amongst many other things) that both the chemical,
>and it's degradation products have reduced to the approved level (which
>is vastly lower than the safe level) in the food part of the crop by
>harvest with a safety margin on top.

Oz, please, we have been through this before. In short:
the safety margin (100) is _needed_ to attain a 'safe' level,
not added 'on top' of it.
<..>

>2) No effect level. Not found since a 2yr study feeding 300mg/kg
>(highest rate used) showed no effects.

"3. Threshold effects-- chronic effects.  The reference dose (RfD)
for glyphosate based on maternal effects in a developmental study with
rabbits (NOEL of 175 mg/kg bwt/day) and using a hundred-fold safety
factor is calculated to be 2.0 mg/kg body weight/day."
([Federal Register: December 24, 1996 (Volume 61, Number 248)])


>3) Environmentl Fate:
>a) Very rapidly excreted by animals unchanged.
>b) Stated as not being metabolised by plants but some evidence that it
>   is.
>c) Strongly bound (ie immobile) in soil. DT50 60 days by microbial
>   action.

There is no reason to believe that plants are generally able to
metabolize glyphosate. Experiments with sublethal dosing indicate
a very persistent effect in perannual plants.

There is good evidence, that glyphosate has a low mobility in soil.

A blank DT50 60 days is misleading; under which conditions (humidity,
soil type, temperature) is this value applicable? What is the range
for DT50 under different realistic conditions? Even the DT50 60 days
indicates that glyphosate is a relatively persistent herbicide.
And some studies have DT50 values at 130-140 days (sandy soils, cooler
climates)

Furthermore a DT50 value should be given with information
of the metabolites produced.
The glyphosate metabolite AMPA is somewhat more mobile than
the parent compound. And the median halflife observed in studies
for AMPA is 240 days, ranging up to 958 days. (EPA Reregistration
eligibility document 1993) With such a persistence even compounds
with low mobility can leach to depths in the soil where no microbial
breakdown is possible.

But let us forget AMPA, please. Monsanto does not want us to talk about
it; and it is (like glyphosate) of low toxicity; and we are trying
to get a global agreement on tolerances (lowest common denominator?):

"EPA seeks to harmonize U.S. tolerances with
CODEX MRLs. CODEX regulates glyphosate per se while the United States
regulates the combined residues of glyphosate and its metabolite
aminomethylphosphonic acid (AMPA). The Agency has determined that AMPA
no longer needs to be regulated and therefore is proposing to delete it
from the tolerance expression"<..>"Upon receipt and review of additional
toxicological data, EPA has determined that AMPA is no longer of
toxicological concern. EPA bases this conclusion on a 90-day feeding
study in rats (EPA MRID #241351) which shows the very low toxicity of
AMPA. Therefore, there is no need to monitor levels of AMPA residue <..>"
(Glyphosate; Proposed Revision of Tolerances,
Federal Register: June 27, 1996 (Volume 61, Number 125))

I have no problem with this. It is just that with the same argumentation
we could scrap all tolerances for glyphosate also. Maybe we should?
In any case, there is an inconsistency problem here. Oh well.

>Note that on food crops spraying glyphosate is confined to timings where
>the food part (eg grain, seed) is past maximum dry matter weight and is
>not absorbing anything from the parent plant. Obviously to do so earlier
>would result in significant yield loss. It is done primarily to kill the
>plant, so that it desiccates rapidly reducing the time to harvest and
>the moisture content of the seed.

>I take it that you are aware that soya and canola seeds are very well
>protected from contact with the chemical by their pods, and wheat by
>it's glumes.<..>

<G> I take it that you are aware, that soya, canola seeds and grain are
not surgically removed from pods or glumes during harvest.
Seeds and grain will of course be contaminated during the harvesting
process.

Don't get me wrong. I am _not_ saying that the use of
glyhosate is a human health hazard. Glyphosate has simply a very
low toxicity, and the practical level  encountered in food
is very far below the level considered safe. If there is one
thing the registration system is good at it is to protect, humans,
humans, humans.

"6. Determination of safety for U.S. population. RfD: The
theoretical maximum residue contribution (TMRC) for existing, published
tolerances for glyphosate is 0.021460 mg/kg bwt/day or 1.0 percent of
the RfD for the overall U.S. population. Using the conservative
exposure assumptions described above, the proposed new tolerances on
corn, sorghum and oat commodities will contribute 0.0023 mg/kg/day to
the TMRC. This aggregate exposure will utilize an additional 0.12
percent of the RfD for the overall U.S. population. <..>
([Federal Register: December 24, 1996 (Volume 61, Number 248)])

So even with worst-case scenarios, the level of Glyphosate in food
will only 'utilize' (sic) little more than 1 % the 2 mg/kg bwt/day,
which all evidence indicate is a safe level.

IF we are really keen on finding health hazards, we should
concentrate on _animal_ health hazards to animals fed commodities with
high levels of residues:

Examples from: Glyphosate; Proposed Revision of Tolerances

Grass forage, fodder, and hay group........................          100
Non-grass animal feeds (forage and hay) group..............          200
Soybean, forage............................................          100
Soybean, hay...............................................          200
Wheat, straw...............................................           85
Sugarcane, molasses........................................         30.0
Wheat bran, middlings, and shorts..........................         20.0
Soybean, hulls.............................................          100

Even at these levels of glyphosate in fodder there may not be any
animal health hazard. A study conducted in Denmark (ISSN 0106-8547)
found no effect on health condition, growth, feed intake,
feed utilization, body composition, or reproduction in young bulls fed
grain (0.8-6.4 ppm glyphosate) and straw (5.6-51.7 ppm).

A similar study (ISSN 0105-6883) (alas, with overall lower levels of
glyphosate in grain and straw than the study above) no effects
were found on pigs fed ethephone _or_ glyphosate treated fodder;
a negative effect on piglet survivability was observed only  in pigs
fed grain/straw which had been treated with _both_ ethephon and glyphosate.

This observation would need further studies before a firm
conclusion can be made. And generally studies using treated crops
is disliked by chemical corporations and registration authorities
who prefer controlled studies with single  active ingredients added to
feed. And to suggest the necessity for studies testing combination
effects, is like farting in a church.
So probably this possible combination effect will never be
subject for further testing.

Concludingly:
The problem with glyphosate is not human health hazard, and
there is probably not animal health hazard either.

Effects on non-target plants from spray drift and from run-off
of glyphosate is much more plausible and they will of course be exacerbated
the more glyphosate is used, and by the extension of glyphosate use
throughout the growth season; this is exactly what is in
store for us after the the introduction of glyphosate resistant crops.


Best regards,

Torsten Brinch

--
Torsten Brinch - Risboege, 6640, Denmark - e-mail: iaotb@inet.uni-c.dk
http://inet.uni-c.dk/~iaotb/            IAO Agrochemical Pages Denmark

Newsgroups: sci.agriculture
Subject: Re: plant pesticides from genetic engineering
From: Oz <Oz@upthorpe.demon.co.uk>
Date: Tue, 4 Feb 1997 19:32:20 +0000

In article <E53086.ICB@emr1.NRCan.gc.ca>, ?@? writes

>Despite the systemic/biochemical action that glyphosate has in killing
>the plants it is used upon, was I correct or incorrect in my
>assumption that glyphosate itself, at a concentration high enough to
>be called "round-up" wouldnt be a good ripening agent, but instead
>would kill the plant?

It is an excellent ripening agent for many crops, particularly
combinable crops in inclement climates. After all at the end of ripening
the plant is dead, that's what straw is.

Having said that it is relatively expensive, there are crop losses from
spraying the crop close to harvest (wheeling damage) and there are often
risks of the crop shedding if combining is delayed. As a consequence
it's use is often restricted to weedy crops where combining would
otherwise be impossible or very difficult.

[Opportunity for someone to have a disagreement here on canola].

--
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"

From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: sci.agriculture,sci.environment
Subject: Re: genetically altered corn??
Date: Sat, 17 May 1997 07:58:50 +0100

In article <5li7fi$t0s$2@news.uni-c.dk>, Torsten Brinch <iaotb@inet.uni-
c.dk> writes

>You should be aware that it is EU policy that pesticides
>and their metabolites should not leach _at all_ to groundwater.
>When that principle was adopted as EU law,
>the permissible contamination was therefore fixed to
>the limit of detection (then) 0.1 mikrogram/liter.

Anyone with even small scientific knowledge would realise that nothing
leaches 'not at all'. I suspect that the idea of a hazard assessment for
each product and it's metabolites was too complex for EU politicians to
grasp.

>as Oz has told you: UK (and I add: other EU countries as well)
>carry on foolhardily.

You should not compare all areas in the EU as being the same. There is
no grain maize and little maize for silage grown in the UK. The only
area with significant silage maize is in SW England. Further east is
predominantly arable and further north is rather too cold for extensive
use. In the SW the rainfall is high and because of the rugged terrain
even there the overall area to maize is rather low. I don't recall any
problems, even incipient ones, being reported concerning atrazine there.

To give you some idea, in the early 70's (as a manager) I grew some
300ac of silage maize and this comprised 0.5% of the *entire* UK maize
acreage at that time IIRC.

>>On the other hand, the herbicides (e.g., 'round-up') for which resistance
>>genes are being introduced into crop plants, are safe, nonpersistent and
>>more effective than atrazine.
>
>Maybe it is. We'll see. Don't believe all you hear or read about
>Roundup, though. It is not as nonpersistent as some would like us to
>think, and neither is it metabolite.
>Although it is apparently rather non-toxic for animals and men,
>it is a horrible plant poison. Until now Roundup has been used in Denmark
>mainly in the autumn, when most plants have stopped active growth.
>If it is going to be used here intensely on genetically modified crops
>(in Denmark that would be sugar beet) it will be _in_ the growth season.
>If this happens, I predict that we will learn a lesson about
>what wind drift of a pernicious and persistent plant poison
>can do to stunt the growth of non-target crops, wild plants and trees.
>Chances are that it will take us many years to see the pattern.

I don't know what regulations are in force in Denmark, but spraying when
drift is likely is not allowed in the UK. Certainly it's not hard to
spray within the field. I have cowslips (very sensitive to hormone
sprays) growing within 300mm of my field edges, and they have been there
for years. The same applies to cowparsley. It's not very hard to do this
and I don't believe that the Danish farmer can be much more incompetant
than I, surely?

When I see this sort of statement I am always reminded of the days when
we were allowed to burn stubbles. This was a very effective way (as we
found to our cost later) of controlling many weeds particularly
blackgrass and it's banning has forced the doubling of my use of
chemicals in kg terms, but I digress. Some years the leaves on trees
facing a burn would, a week or two later, go prematurely brown and fall,
which we attributed to the heat of the fire. It was mildly odd that it
only occurred on the same side each year (ie not the other), and the
technique we used should have resulted in very little heat stress around
the perimeter, but no matter. After we stopped burning we noticed, to
our surprise, that most years this leaf browning and fall still
continued. Basically on sandy/gravel soil in a dry summer the south and
southwest sides of trees lost their leaves early due to drought stress
and the burning had little if anything to do with it. This is a caution
that even things that are *obviously* a cause, sometimes are not.

--
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"

From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: alt.agriculture.misc,alt.sustainable.agriculture,sci.agriculture
Subject: Re: "True cost" of large-scale organic farming
Date: Wed, 10 Sep 1997 08:36:35 +0100

In article <34160866.7807298@news.mindspring.com>, Michael E Ross
<michaelross@mindspring.com> writes

>This is incorrect, glyphosate has a half life of 1 to 174 days
>depending on the microbial activity of the soil.  If the soil is
>particularly low in microbial activity (the persistant use of -cides
>can cause this) this equates to nearly a year.

Ho,ho,ho! ONE to 174 days. Wow, nothing like having an extreme range,
eh? Since it's strongly bound to the soil (which is why soil-applied
glyposate had no effect on plants) we don't have to worry about
leaching. So the effect on the soil is pretty much zero. Now if you
spray it on a desert where there is no microbial activity then it just
stays there until there are suitable conditions for breakdown (like it
rains) and if you sprayed it on near frozen ground then I guess it would
just stay there until it warmed up. Either way it's not causing anyone a
problem until conditions become suitable for the bugs to grow, whereupon
they eat it for food. Quickly.

Panic not.

>Regarding the lack of toxicity of glyphosate: the acute lethal dose
>for 50% of rats (AKA acute LD50) is .0056 grams per rat kilogram.  Not
>really in the same arena as water and salt as Oz mentioned earlier.

Oh dear, you have made a 'slight' error here. It's only by a factor of
1000, though, so we should be grateful. The LD50 for rats is 5600mg/kg
which is 5.6grams/kg. Now we had this discussion a while ago comparing
it to common salt. Lets see, for a 70kg human we are talking LD50 of
400gms, I think it would take less common salt to be fatal, much less.
Anyhow it's of the same order (probably safer, I forget) as common salt.

Panic not.

>LD50 is a cheap and dirty way to get some sort of idea how poisonous a
>substance is.  It is notably more difficult t tell the long term
>effects of exposure.  I prefer to be as safe as possible...

Indeed so. However (The Pesticide Manual 10th Ed) "Glyphosate is very
rapidly excreted unchanged in mammals". I am not sure what level is
allowed in foods, I would guess somewhere in the microgramms/kg or a few
orders of magnitude less. There are many vastly more dangerous things
about in your life so I personally won't lose the slightest amount of
sleep over it.

>A few years ago I had the misfortune to live within a couple hundred
>yards of cotton (aerial sprayed) in about 270 degrees of a circle from
>my porch.  I can't tell you how good that all sounds for my
>ex-neighbors.  I guess it is better than what they put up with now.
>The "farmer" of those fields (I should say the guy who hires the
>people who tend that land) lives quite far removed from any such
>activity.

1) Note my comment on aerial spraying. Virtually non-existant in the UK.
2) Note my comment on farmers who live on, farm and own the farm vs
others.

>
>This is excerpted from the site mentioned above concerning Cygon (
>Dimethoate).
>
>ACUTE TOXICITY

Snip. Note that a typical concentration of dimethoate in ground spray is
around 0.1% (200g active in 200l water).

>     The amount of a chemical that is lethal to one-half (50%) of
>experimental animals fed the material is referred to as its acute
>oral lethal dose fifty, or LD50.  The oral LD50 for technical
>dimethoate in

Ok about (being generous) 200mg/kg. For our standard 70kg human this is
14gms. This is equivalent to consuming 14 liters of spray right out of
the sprayer tank (ugh!!). I guess you will be pretty sick even if you
don't peg it. (Actually I've never done this estimate before, it's much
safer than I thought, by a lot. I would have guessed a few tens of ml's
would be enough.)

>I have to ask...What the heck happend to the label?

On the can.

>I hope the original post does not contribute to anymore "folklore."

One might say the same about yours.   :-)

Whatever you do do NOT look up Malathion and it's use for treating head
lice in children. It's 1% in alcohol (stronger than the sprayer spray)
rub in thoroughly and leave for 20 mins, then wash off. Malathion is
comparable in toxicity to dimethoate!

Isn't life fun?

--
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"

From: Oz <Oz@upthorpe.demon.co.uk>
Newsgroups: alt.agriculture.misc,alt.sustainable.agriculture,sci.agriculture
Subject: Re: "True cost" of large-scale organic farming
Date: Thu, 11 Sep 1997 07:25:01 +0100

In article <34176a56.1835864@news.mindspring.com>, Michael E Ross
<michaelross@mindspring.com> writes
>
>Oz <Oz@upthorpe.demon.co.uk> wrote:
>
>>In article <34160866.7807298@news.mindspring.com>, Michael E Ross
>><michaelross@mindspring.com> writes
>>
>>Ho,ho,ho! ONE to 174 days. Wow, nothing like having an extreme range,
>>eh? Since it's strongly bound to the soil (which is why soil-applied
>>glyposate had no effect on plants) we don't have to worry about
>>leaching. So the effect on the soil is pretty much zero. Now if you
>>spray it on a desert where there is no microbial activity then it just
>>stays there until there are suitable conditions for breakdown (like it
>>rains) and if you sprayed it on near frozen ground then I guess it would
>>just stay there until it warmed up. Either way it's not causing anyone a
>>problem until conditions become suitable for the bugs to grow, whereupon
>>they eat it for food. Quickly.
>
>If you read the info in the website you will see that it carefully
>outlines that the only mechanism for breaking down glyphosate is
>microbial activity.

Did I disagree? However that's not the whole story.

>What Gordon said is that glyphosate breaks down when it comes in
>contact with the ground.  If the information in this site is correct,
>then a sterile soil would not have much effect of an immediate on the
>glyphosate.  I presume that this is why there is a wide range of half
>life for the herbicide.  I don't get the humor or irony of this.  A
>year is a long time not to be able to grow things.

Because you *can* still grow things. It's so strongly bound to the soil
that plants can't take it up. In fact you can spray glyposate over
germinating small seeds to kill the top weeds but leave the germinating
seeds unaffected. In ag parlance it's contact activity is high, and soil
activity is zero.

>I would be
>dissappointed with any decrease in the ability of soil to support
>plant growth, even a day.

It doesn't affect the ability of the soil to grow plants, it doesn't
work once it hits the soil due absobtion. Some chemicals ONLY work by
root uptake and have no contact action. This often has advantages in
particular situations (like keeping your drive free from weeds all
season).

>(A poster in another group was asking why, after applying Roundup,
>nothing would grow  (significant time had elapsed).  Not knowing all
>the particulars, one cannot say if it was appied correctly, or what
>other factors could have affected the situation.  One possible cause
>would be the persistence of glyphosate due to a lack of the soil's
>ability to break it down.

Nope.

>If she waits long enough she will be able
>to grow something.  You would not expect this if your only source of
>info was advertising.)

I have used gallons of the stuff. It's effective, safe, and expensive.
No soil activity.

>Do you have any basis for disagreeing with information in the EXTOXNET
>website?  If not, then why rag on my statement about it being possible
>for the stuff to persist for nearly a year?

It's mostly that you have not correctly interpreted it. It has some
half-life in the soil, but it's so stronly bound that it doesn't get
picked up by the plants. Paraquat is similar.

>>>Regarding the lack of toxicity of glyphosate: the acute lethal dose
>>>for 50% of rats (AKA acute LD50) is .0056 grams per rat kilogram.  Not
>>>really in the same arena as water and salt as Oz mentioned earlier.
>>
>>Oh dear, you have made a 'slight' error here. It's only by a factor of
>>1000, though, so we should be grateful. The LD50 for rats is 5600mg/kg
>>which is 5.6grams/kg. Now we had this discussion a while ago comparing
>>it to common salt. Lets see, for a 70kg human we are talking LD50 of
>>400gms, I think it would take less common salt to be fatal, much less.
>>Anyhow it's of the same order (probably safer, I forget) as common salt.
>
>You are quite right.  I am chagrinned .  I always had a knack for
>blowing unit conversions in my head.  Thanks for correcting me.  Do
>you happen to know the LD50 for water and/or salt (since they are your
>analogy)?

We had this discussion fairly recently. Water for 600kg cattle is about
40 galls or so. I can't remember the NaCl one for sure (we were
discussing nitrates) but 300gm is about there. Actually when salt was
used as a home remedy as an emetic for kids, quite a few died each year
as a result. I doubt you could give a kid more than 30 to 60 gms.

>Furthermore, regarding the LD50 of glyphosate, that 5.6g/rat kg is for
>pure unadulterated glyphosate.  I have no idea what concentration the
>OTC stuff is.  You would have to factor that in to see how much
>storebought Roundup it would take to kill 5 out of 10 rats.

Ag stuff is 36%, some 48%. Garden stuff will probably be very much more
dilute.

>>>LD50 is a cheap and dirty way to get some sort of idea how poisonous a
>>>substance is.  It is notably more difficult t tell the long term
>>>effects of exposure.  I prefer to be as safe as possible...
>>
>>Indeed so. However (The Pesticide Manual 10th Ed) "Glyphosate is very
>>rapidly excreted unchanged in mammals". I am not sure what level is
>>allowed in foods, I would guess somewhere in the microgramms/kg or a few
>>orders of magnitude less. There are many vastly more dangerous things
>>about in your life so I personally won't lose the slightest amount of
>>sleep over it.
>>
>
>Now you are making stuff up, even if it seems reasonable.

Nope. Exact quote.

>Don't get me wrong, I am really glad this stuff is easier on the
>mammalian system than other herbicides.  I still would just as soon we
>did without it.

Me too. I have to pay for it.

>If you want base your estimates for safe exposure on acute LD50, then
>I expect the Darwin of old to have his way with you.

I don't. I never suggested they were safe. The LD50 is VERY far from a
safe level. It is, however, a useful estimate of what most people would
consider 'the lethal dose', and is easily understandable. It has many
disadvantages as a measure, this is true.

However when someone hears that 1% of vegetables have above the 'safe'
limit of 1 part per billion and panics, it's helpful to know that this
is a mindblowingly small amount and isn't really a 'safe' limit but
orders of magnitude below it. It's the 'allowed' limit. The regulators
set these limits with truly vast safety margins, which is quite right.
However these microscopic levels certainly do not set a safety limit,
they are orders of magnitude below. It's one of the irony's of life that
the huge levels of safety required of ag chemicals and the microscopic
amounts allowed in produce has resulted in the rare case of stuff just
over the 'limit' (usually imported) and this is described in the press
as 'above the safe limit' which is actually completely untrue. Often by
factors of 1000 or 1,000,000. This means people are making judgements on
incorrect 'facts'. I deplore this.


--
'Oz     "Is it better to seem ignorant and learn,
         - or seem wise and stay ignorant?"