!Halflife of Pesticides?(Re:Major brain fart there)

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Posted by Brenda on January 16, 2001 at 20:18:00:

In Reply to: Re: Major brain fart there..... posted by BabyHerp on August 14, 2000 at 17:24:12:

I don't know anything about pesticides but I remember from high school that half-life regarding carbon dating is different the process you describe for chemicals.
In carbon dating or other halflife dating, half of the carbon 14 molecules have deteriorated(?) at the end of one half life and then another half of those half left have deteriorated after another full half life time span.
If this method was applied to a pesticide halflife of 90 days, after 180 days the inert amount would be 1/2 of the original level PLUS 1/2 of 1/2 (or 1/4) totaling 3/4 inert and 1/4 active after 180 days).

After the third lapse of the same halflife, another 1/2 of that amount would deteriorate, or 1/2 of 1/2 of 1/2, or 1/8.
The total inert amount after 270 days would therefore be 1/2 plus 1/4 plus 1/8, or 7/8.
The active portion would be 1/8 of the original.

Therefore, after 270 days, 12.5% would still be active.
After 360 days (or almost 1 year) half that amount would still be active: 1/16, or 6.25%...still a significant amount.

I've been away from school for a while so I may be wrong on this.

: I was being super conservative suggesting not to feed pesticide/herbicide grown produce to igs if your yard is being sprayed for one year... actually more like a month or 2 *depending* on the chemical. Important to find out what the half-life of the chemical used is....some chemicals are guaranteed to last up to one year others a few months or days even. Like termite, ant sprays...some are pretty heavy duty!
: What produce isn't treated with herbicides & pesticides these days huh? but a few things Ive read about that might be interesting to investigate is:
: soil leaching/erosion (chemicals getting into the soil, root systems, trunks of plants & trees)
: wind effects pesticides (more wind less concentration on top soil)
: harvesting....produce is no longer affected because cut from the root system
: Most important in determining when to use affected produce for food is: half-life of the pesticide or herbicide used: I don't know what the half life of termite spray is but lets say the half/life of a termite spray on your house is 90 days...that means...in 90 days 1/2 of the pesticide is destroyed,its non-effective. And subsequent days continue gradually lessen the concentration of the pesticide until its no longer doing anything intended for its purpose, becomes inert in another 90 days. Make sense?
: Washing produce real well helps
: Cooking out pesticides & herbicides also effective

: Im notorious for not washing the produce I buy or steal (hehehe) very well....I think that's how one of my iguanas got hookworm....from ova contaminated dandelion greens I bought at a community garden some months back...prolly didn't wash em very good.
: Notice how there are a bunch of products being offered now to wash produce, seen any of these at the market? Im wondering what's in em? Gonna have to check it out. I thought water was enough to wash produce of residual pesticides, herbicides & parasites.....guess not.
: Anyway...I'd check out the chemical you used before feeding anything that may have affected em to your ig. I don't know what was sprayed so I shouldn't of posted such a general statement like that! Ya think? Sound better? Less paranoid? lolol
: No??? Doh!
: Gina

City and County of San Francisco, Integrated Pest Management, Program Report, Reduced Risk, Pesticide List 2000, Debbie Raphael, Philip Dickey, Francesca Vietor, March 2000

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: I don't know anything about pesticides but I remember from high school that half-life regarding carbon dating is different the process you describe for chemicals. : In carbon dating or other halflife dating, half of the carbon 14 molecules have deteriorated(?) at the end of one half life and then another half of those half left have deteriorated after another full half life time span. : If this method was applied to a pesticide halflife of 90 days, after 180 days the inert amount would be 1/2 of the original level PLUS 1/2 of 1/2 (or 1/4) totaling 3/4 inert and 1/4 active after 180 days). : After the third lapse of the same halflife, another 1/2 of that amount would deteriorate, or 1/2 of 1/2 of 1/2, or 1/8. : The total inert amount after 270 days would therefore be 1/2 plus 1/4 plus 1/8, or 7/8. : The active portion would be 1/8 of the original. : Therefore, after 270 days, 12.5% would still be active. : After 360 days (or almost 1 year) half that amount would still be active: 1/16, or 6.25%...still a significant amount. : I've been away from school for a while so I may be wrong on this. : : : I was being super conservative suggesting not to feed pesticide/herbicide grown produce to igs if your yard is being sprayed for one year... actually more like a month or 2 *depending* on the chemical. Important to find out what the half-life of the chemical used is....some chemicals are guaranteed to last up to one year others a few months or days even. Like termite, ant sprays...some are pretty heavy duty! : : What produce isn't treated with herbicides & pesticides these days huh? but a few things Ive read about that might be interesting to investigate is: : : soil leaching/erosion (chemicals getting into the soil, root systems, trunks of plants & trees) : : wind effects pesticides (more wind less concentration on top soil) : : harvesting....produce is no longer affected because cut from the root system : : Most important in determining when to use affected produce for food is: half-life of the pesticide or herbicide used: I don't know what the half life of termite spray is but lets say the half/life of a termite spray on your house is 90 days...that means...in 90 days 1/2 of the pesticide is destroyed,its non-effective. And subsequent days continue gradually lessen the concentration of the pesticide until its no longer doing anything intended for its purpose, becomes inert in another 90 days. Make sense? : : Washing produce real well helps : : Cooking out pesticides & herbicides also effective : : Im notorious for not washing the produce I buy or steal (hehehe) very well....I think that's how one of my iguanas got hookworm....from ova contaminated dandelion greens I bought at a community garden some months back...prolly didn't wash em very good. : : Notice how there are a bunch of products being offered now to wash produce, seen any of these at the market? Im wondering what's in em? Gonna have to check it out. I thought water was enough to wash produce of residual pesticides, herbicides & parasites.....guess not. : : Anyway...I'd check out the chemical you used before feeding anything that may have affected em to your ig. I don't know what was sprayed so I shouldn't of posted such a general statement like that! Ya think? Sound better? Less paranoid? lolol : : No??? Doh! : : Gina

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