Dave Fischer,
Director, Ecotoxicology
Research and Development Department
Bayer CropScience LP

said:

"Take the lowest published oral LD50 value for
imidacloprid (3.7 ng/bee) and convert it to an equivalent food
concentration (you do this by dividing by the amount of food (26 mg) bees
ingest on average during acute oral tests).  3.7 ng / 26 mg = a
concentration of 142 ppb"

From
http://www.honeybeeworld.com/imidacloprid/canada.htm

"In my initial presentation I gave you an appendix which was a paper by
Bayer authors Schmuck, Schoning, Stork and Schramel , "Risk to
Honeybees...." which I think will certainly be mentioned today. It says in
the abstract that to bees imidacloprid has "...high oral toxicity...with
values between 3.7 and 40.9 nanograms per bee, corresponding to a lethal
food concentration of between 0.14 and 1.57 mg/kg." Those food concentrates
translate to 140 to 1,570 parts per billion. This is a very important
statement because Bayer is using it to relate an LD50 (an experimental value
of the dose weight per bee, which when taken orally is lethal to 50 % of the
victims in 48 hours) to a toxic concentration in plants, and it is
completely speculation. 3.7 billionths of a gram per bee only translates to
140 ppb in a plant if you dose the bees with the toxin in 26 milligrams of
solution (or 20 mg of solution and apply the formula on page 235 of the
paper).

From Bayer's book, The Life of the Bee: "Despite itself weighing barely 100
mg, it (a bee) is able to transport up to 75 mg of pollen and nectar. ... It
can make 30 pollen-gathering flights daily or 150 visits to a source of
nectar or 110 water collecting flights. If you use those figures, you can
calculate that a forager bee can gather 10 grams of nectar or 4.5 grams of
pollen in 48 hours. Now I would not be so foolish as to claim that we use
those amounts. The bee does not metabolize most of the nectar it is
carrying. Nor would I claim that the bee is contacting all the toxin in the
pollen it is carrying (the contact LD50 according to Bayer's Schmidt is 81
nanograms/bee). Much would be in the endoplasm of the pollen and would only
poison the nurse bees and the brood. But it is equally foolish for Bayer to
claim that they can relate an LD50 to a ppb using a single dose of 26 mg.
Their own book says that bee foragers will fly 800 km in a couple of weeks.
They need to metabolize one honey stomach of nectar (75mg) for each 10 to 13
km of flight, so they certainly metabolize many times more than 26 mg. in 48
hours."

From a personal comunication (I can not disclose the source) when asking
help about a contamination problem I had in Chile with Carbaryl (from
Bayer).

"You got to watch how the labs report stuff, UG/KG is parts per billion ppb.
MG/KG is parts per million. The chemical companies like to play games and
try and make beekeepers do math to figure out how much carbaryl kills bees,
this sentence quoted from the EPA IRED explains it much better because no
math is needed. "Carbaryl is highly toxic on acute contact basis LD50
.0011mg/bee" Carbaryl is 10 times more toxic by ingestion, or .00011 mg/bee.
Converted that is 1.1ppb/bee.

In my case the Lab reports the following Carbaryl contamination of my bees

Sample N°1 : 0.28 mg/Kg
Sample N°2: 0.04 mg/Kg.

I ask the Lab how that figure compared with 1.1 ppb/bee and they answer:

"We counted 20.000 bees per Kilo therefore would that be: 0.28/20000 =
0.00014  mg/bee  / 1000 = 0.000000014 ppb/bee"


Mr Fischer :

Which is the correct figure? How can we trust Bayer research?  How we
transform from/to all this figures:  ng/bee ug/bee mg/bee ppb ppm mg/kg and
so on and so for?


-- 
Juanse Barros J.
APIZUR S.A.
Carrera 695
Gorbea - CHILE
+56-45-271693
08-3613310
http://apiaraucania.blogspot.com/
[log in to unmask]

****************************************************
* General Information About BEE-L is available at: *
* http://www.honeybeeworld.com/bee-l/default.htm   *
****************************************************