Organic produce is supposed to be free from synthetic chemicals and governed with strict guidelines.
But NewsChannel5 found no established testing procedures are in place.
"USDA Certified" is the label to look for when spending extra money on organic produce. And that price tag can be 20 percent to 30 percent higher than conventionally grown produce.
Consequently, organics have grown into a multi-billion dollar industry.
Act of 1990
Organics are overseen by the Organic Foods Production Act of 1990 .
It required the United States Department of Agriculture to set up an organics program to oversee processing, distribution and certification. It's called the National Organic Program.
The program in turn, oversees third party certifiers around the world who give products the USDA Certified stamp of approval. According to the USDA, there are 85 certifying agents who handle about 30,000 operating farms.
The law also requires a strict examination of "residue testing" for pesticides.
But now, 22 years after the law was enacted, those tests are not happening.
Miles McEvoy heads the organics program for the USDA.
The Office of the Inspector General did an audit of the program in 2010. The report states that the organics program did not establish testing procedures and the certifying agents were not performing periodic residue testing as required by law.
"Congress indicated that certifiers should be doing periodic residue testing and that had never been established," said McEvoy.
NewsChannel5 joined with 10 of our Scripps stations across the country and went to various stores to purchase imported organic produce.
We bought a wide variety with each station buying different products.
Each of the samples from across the country was shipped overnight to the same certified lab in California.
Wil Sumner headed the testing project. He has been a chemist for more than 35 years. Today he runs his own company.
"By definition, organic does not mean chemical-free. It just means it is grown without the use of synthetic pesticides and fertilizers," said Sumner. "It doesn't mean that they are not toxic."
In all, the lab tested 33 different types of organic produce imported from 11 different countries.
We found 12 percent had pesticide residues with an additional 10 percent having trace amounts.
It is true some farmers use chemicals when they shouldn't. But more often, contamination comes from the soil where toxic chemicals like DDT were used decades ago. These toxins are not going away anytime soon.
There is also cross-contamination.
"There are a lot of different compounds out there, and they are being used by both groups -- conventional and organic growers. And, these are all drifting in different directions," said Sumner.
In addition to conventional pesticides blowing onto organic farms, Sumner said cross-contamination could happen in the shipping process. It could also happen in the back room of the store.
Four of our organic produce tested positive for residues. They all came from Mexico.
The lab found a chemical called, Dieldrin in the mini pumpkins we tested and DDD in the yellow squash -- a cousin of DDT. Both are extremely toxic. Both are banned, and both will remain in our soil for decades.
The tomatoes had residue of Spinocyn-A, which is a conventional pesticide recently approved for organics.
All three of the items had small amounts of chemical residue and would be allowed for sale by the USDA.
But, the fresh basil we bought had Metalaxyl in it, which Sumner said wasn't legal for organics. He said the Food and Drug Administration would make all retailers pull that product from shelves.
Periodic Residue Testing
The good news? The government is finally setting up guidelines for testing.
NewsChannel5 found this memo from McEvoy requiring all third party certifiers to start testing 5 percent of operating farms both here and abroad. This testing is supposed to start this year.
The new periodic residue testing program will discourage mislabeling and facilitate our oversight of USDA organic products around the world. This will allow us to prevent residues of a wide variety of prohibited substances, thus meeting consumer expectations. Periodic residue testing is an important tool to protect the integrity of USDA organic products around the world.
"How well that's implemented overseas? Can the USDA have the staff over there to make sure it is being run the same? That's the question," said Sumner.
However, on all produce you buy, Sumner recommends to simply wash your food. That can remove about 50 percent of residues.
Studies have been done to see if organic produce is safer, healthier or more nutritious. They have not proven that to be the case. Read more from the Mayo Clinic and from the Stanford School of Medicine .