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.
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.