It's true that organic does not mean pesticide free. They are allowed to use a wide variety of organic pesticides some of which can be harmful even to humans according to some studies. I should have clarified that I feel the organic produce has more ability go be washed clean. But you can't be sure it's safe just because it's organic. At our farmers market I can sometimes find pesticide free produce, but you can't be sure no matter what store you shop at. Just have to wash it the best you can. But I also grow my own greens when weather permits and those I know are free of chemicals.
This was back in the 1990's, but the trouble we saw was that farmers, even corp farmers, used to buy pesticide mixes which contained several compounds for whichever kind of crop they had. The farmer usually did not know what was in the mixture, and they assumed it was all USDA legit.
But as time went on, some pesticides were banned, but they were still using the same old mixture.
Most of these compounds have a very long shelf life, they do not have expiration dates. So farmers can use the same mix for years.
Another problem was that most of the pesticides went by different names; chemical name, brand name, etc.
Spot checks were performed by USDA on farms, and I personally know of a few big corp farmers who had to plow an entire crop under because an illegal pesticide was detected, the lose can go into the millions of dollars.
As a scientist, if I determined a farmers crop had a high amount of an illegal pesticide, or any pesticide which is not approved for that crop, and reported the data from my analysis, I better know what I am
saying, because I could face a prison term if I am proved wrong.
This includes any lab techs who assisted me in my analysis, and my manager!
In such a case, the suspect sample is sent to other labs to verify, and we would perform analysis again in our own lab using a different method.
In some states, data from HPLC can not be used as evidence in court simply
because it is often not accurate enough and is open to interpretation.
We would use HPLC/MS or GC/MS to confirm, as this is not contestable.
Bottom line.... no, you really don't know what you are eating
