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Comment by keenerd | Hacker News Reader

As someone who comes from a family of small farmers, this is not really true. Organic pesticides are on-average more harmful to the people who use them than modern pesticides. Simply put, organic pesticides attack animal/fungal life indiscriminately. Including human life. Most organic pesticides will kill you at fairly low quantities. Most man-made ones won't, they are tailored to a task. And organic farmers need to use a lot more pesticides than non-organic farmers to achieve the same results, making human toxicity even more likely.

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I've never heard of this. Do you have an actual source?

I'm interested in a source as well.

I have heard the argument that organic pesticides must be used in higher quantities, but never that they are more toxic than synthetics.

The latter statement seems nonsensical on its face. It's very difficult to believe that, given years of testing and research into both synthetic and organic pesticides, so many people are getting it so wrong as to conclude that organics are safer when they are exactly they opposite.

In fact, non-organic farming proponents aren't even making this claim to my knowledge. At most, they seem to advocate that non-organics aren't less healthy than organics.

I think they are referring to the loophole that allows farms to use organic chemicals on produce that is labeled "Organic".

In chemistry, an organic chemical is a compound that contains lots of carbon, or carbon chains. The loophole allows the use of these organic compounds as pesticides. The downside is that these are typically much more of a broad spectrum than the cutting edge pesticides. This means that unlike the new narrow-spectrum pesticides (which are often designed so they only affect the physiology of a specific order of invertebrate) the old-school organic chemical pesticides are harmful to pretty much everything it comes in contact with.

Here is some more info on the issue: http://www.ocf.berkeley.edu/~lhom/organictext.html

http://blogs.scientificamerican.com/science-sushi/2011/07/18...

And one last one that explains a bit more on organic chemicals: http://www.chemheritage.org/percy-julian/activities/2b.html

Only primary sources. Pick a few chemicals, find their LD50 from a MSDS, find their application rate. Run the numbers.

An organic fungicide: copper sulfate pentahydrate (aka CuSO4)

A non-organic fungicide: iprodione (aka Rovral)

LD50 of CuSO4: 472 mg/kg (rat) [1]

LD50 of Rovral: 2g/kg (rat) [2]

So straight up, the organic is four times more lethal to mammals. But that is just the beginning, because you have to use a lot more of the organics! How much would Farmer Joe have to use on his small, 10 acre plot? Assuming the worst, lets look at the maximum seasonal application.

rate of CuSO4: 16 pounds/acre per season [3]

rate of Rovral: 12 pints/acre per season [4]

Skipping the basic algebra, in one year Joe could apply enough organic fungicide (72.5kg) to kill 1700 people. One year of non-organic (1.3kg) would be enough to kill 7 people. (Assuming a spherical man of 90 kg.)

[1] http://extoxnet.orst.edu/pips/coppersu.htm

[2] http://www.cdms.net/ldat/mpAKR005.pdf

[3] http://growabundant.com/copper/

[4] http://www.cdms.net/ldat/ldAKR006.pdf

edit: ambago, you are full of bunk. The USDA has very strict guidelines for labeling. See http://en.wikipedia.org/wiki/Organic_certification

LD50 (acute toxicity) does not necessarily correlate with harmful health effects from chronic exposure. Can you cite studies that demonstrate harms from exposure at the levels used in organic farming?

We are talking about risks to people working in the fields. Every time a farmer applies anything to a field, he will have to put on safety gear, measure out an amount, mix it with water, load it into the sprayer, drive the tractor around, and then clean up afterwards. When you are working with enough of a chemical to kill a hundred people, every single one of these steps carries the risk of an acute exposure. Dead is dead, regardless of how it happens. Don't dismiss it.

edit: From source [1]:

> Chronic toxicity: Vineyard sprayers experienced liver disease after 3 to 15 years of exposure to copper sulfate solution in Bordeaux mixture [8]. Long term effects are more likely in individuals with Wilson's disease, a condition which causes excessive absorption and storage of copper [25]. Chronic exposure to low levels of copper can lead to anemia [8]

So yeah, its still bad for you.

LD50 is one measure. For the consumer, half life and non-acute toxicity is probably a better measure to use.

The organophosphate (e.g., methyl chlorpyrifos, dimethoate, methidathion and methyl parathion) pesticides used in conventional agriculture have half lives of a little less than a week to two weeks on the surface (and a half life of years in water and soil), while pyrethrins have a half life of hours in sunlight and 2 weeks in soil.

Both organophosphates and pyrethrins have toxic effects on mammals, but one is less likely to be present on purchased produce since, at least, four half lives (97% degraded) will have passed for pyrethrins, in a single day.

In the extreme, organochlorines (e.g., aldrin, chlordane, dieldrin and dicofol [OK, DDT and such are in this class too]) were spayed on conventional crops. These have half lives measured in years (on the surface), and their residues are found, in the environment, decades after specific compound bans.

Finally, US grown rice/citrus contains arsenic (there is no safe limit established for inorganic arsenic) because of conventional pesticides containing arsenic being sprayed on cotton fields (California rice/citrus is generally safer than that grown in Southern states).

All this said, I believe (opinion) that USDA organic allowing the use of so many pesticides was a give away to big ag, so they could participate in the "organic craze" without substantially changing their production practices. Personally, I buy pesticide free vs. organic when available.

Perhaps I generalized a bit too much (I suppose I should not have commented when I was dead tired...) However, the USDA does in fact allow non-prohibited chemicals to be used on USDA certified organic produce.

USDA National Organic Program: http://goo.gl/OUCAXM USDA National List of Allowed and Prohibited Substances: http://goo.gl/YXLUJ5

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