Switching to organic apples because they top the "Dirty Dozen" list of produce with the most pesticides? You may want to reconsider. It turns out the "Dirty" foods are fairly clean, and organic foods aren't free of pesticides anyway.
The "Dirty Dozen" Rankings Aren't Connected to Safety
The "Dirty Dozen" list, which aims to rank the fruits with the most pesticide residue, comes from the Environmental Working Group, and they publish their methodology on the report's website. They basically download the test results from the USDA's Pesticide Data Program, which samples produce for pesticide residues, and come up with a ranking score for each fruit or vegetable based on six criteria relating to the number of different pesticide residues seen on produce of that type, the percentage of samples with pesticide residues, and the total amount of pesticide detected.
There's a problem here. Some pesticides are drastically more toxic than others, but the EWG's scoring system considers all pesticides to be equal, and they don't relate the pesticide amounts to known safety standards. Two food scientists did a reality check on the EWG's numbers from their 2010 list (which uses the same methodology as this year's). Their analysis was published in the Journal of Toxicology.
They compared the amount of pesticides on each of the Dirty Dozen foods to the chronic reference dose, which is the maximum amount that it's okay to have if you are eating that food every day of your life. This level, just to be safe, is one hundred times less than the amount that experimental animals were able to consume with no effects. It's a pretty big safety margin. So how many of the Dirty Dozen exceeded this extremely conservative chronic reference dose? None:
All pesticide exposure estimates were well below established chronic reference doses (RfDs). Only one of the 120 exposure estimates exceeded 1% of the RfD (methamidophos on bell peppers at 2% of the RfD), and only seven exposure estimates (5.8 percent) exceeded 0.1% of the RfD. Three quarters of the pesticide/commodity combinations demonstrated exposure estimates below 0.01% of the RfD (corresponding to exposures one million times below chronic No Observable Adverse Effect Levels from animal toxicology studies), and 40.8% had exposure estimates below 0.001% of the RfD.
So even the dirtiest of the dozen had pesticide levels that are very, very, very low. Which brings us to the other fundamental problem with the ranking-based Dirty Dozen: the list will always have twelve items on it. If farmers increased their pesticide use by a million times overnight, or if they abandoned pesticides in droves, next year's list wouldn't reflect the change in your actual risk. It would still be a dozen items long, and the "Clean Fifteen" would still endorse fifteen others.
The "Clean Fifteen" is worth some scrutiny, too: in another analysis, the vegetable with the highest dose of pesticide was on that list: cauliflower, with more pesticides over 10% of the RfD than other crops. Let's stop pretending the EWG's lists tell us anything about what is actually safe in our food.
Organic Farming Uses Pesticides, Including Very Toxic Ones
Maybe you want to avoid any pesticides at all. I can get behind that. There's no risk lower than zero, right? The problem is that the EWG's solution—buy organic if you are concerned about pesticides—won't necessarily reduce your pesticide intake.
Organic farming uses pesticides too. In fact, here is the National List of pesticides approved for organic certified farms. It includes some fairly toxic substances, like copper sulfate, and many are not restricted in terms of how much a farmer can use. Just because "synthetic" pesticides are more strictly regulated doesn't mean the natural ones are healthier: Back before rotenone was banned, it was allowed on conventional and organic crops alike, since it comes from a plant rather than a synthetic source. Organic pesticides aren't necessarily better for the environment either.
This would be a moot point if we could compare the pesticides found on organic and conventional produce. You'll notice that the EWG only mentions the pesticides found on conventional produce: that's because the USDA doesn't test for organic pesticides.
They use a high-speed method that lets them test for hundreds of pesticides at a time, but the test can't detect many organic pesticides including copper sulfate and Bt toxin (famous for its role in GMO corn and soy, but it's also perfectly legal in organic farming).
We know that organic produce has less of the synthetic pesticides than conventional produce does (not zero, but less). But we don't have complete information on the total pesticide load, synthetic and organic, so it would be wrong to claim that organic produce has less. We just can't say.
What You Should Do
First, keep eating lots of fruits and veggies. The health benefits of eating them (any kind) are well established, and massively outweigh any risk from pesticide residues (organic or otherwise).
But how can we ensure we're getting the lowest possible pesticide residue on our foods? Wherever I looked for an answer to this question, the recommendation was always the same: buy from local farms where you can ask how they control pests and what chemicals they use. Apple farms are non-organic in most parts of the country, for example, but many of those use sustainable pest management techniques that keep their pesticide use very low. I'm happy to buy from those farms.
I'm not arguing against organic food in general. The organic movement has a lot of good intentions behind it. The USDA Organic label doesn't reflect intentions, though. It means a few specific things, for example that food hasn't been irradiated, that animals aren't routinely given antibiotics, and that certain fertilizers and certain pesticides weren't used. Some of these things may matter to you, and some may not. You may also find that some things that do matter to you aren't reflected by the presence or absence of organic certification.
So, forget the organic label if you're concerned about pesticide exposure; it just doesn't tell you what you want to know. Ask questions—or grow your own, if you can—and forget the "Dirty Dozen."