The 'Dirty Dozen' and Kale's Pesticide Profile
Every year, the Environmental Working Group, a non-profit consumer advocacy organization, releases its 'Shopper's Guide to Pesticides in Produce', which includes the now-infamous 'Dirty Dozen' and 'Clean Fifteen' lists. The Dirty Dozen names the 12 fruits and vegetables with the highest amount of pesticide residue, based on samples tested by the U.S. Department of Agriculture (USDA) and the Food and Drug Administration (FDA). Kale made a notable appearance, and in some years, a single sample of conventionally grown kale was found to contain as many as 18 different pesticide residues.
One pesticide frequently detected on kale is Dacthal (DCPA), which has been banned in Europe since 2009 due to its classification as a potential human carcinogen by the U.S. Environmental Protection Agency (EPA). This is often soil-applied, meaning the plant can absorb it directly, and washing doesn't remove it entirely. The complex, crinkled surface of kale leaves also makes it more difficult to wash away surface-level pesticides compared to smoother produce.
Organic vs. Conventional Kale: What's the Difference?
The primary distinction between organic and conventional kale is the method of farming and the types of pesticides used. While organic farming still uses pesticides, they are derived from natural sources, whereas conventional farming relies on synthetic chemicals.
- Organic Kale: Studies suggest that organically grown kale can be more nutritionally dense, containing higher levels of total sugars and essential minerals like potassium and sodium, as well as fiber. This is often attributed to the enhanced microbial activity and healthier soil that organic farming practices foster.
- Conventional Kale: Contains detectable pesticide residues, with testing revealing multiple types of pesticides on a single sample. The nutritional content can be comparable or slightly lower than organic varieties, but the key concern lies with the presence of chemical residues.
| Feature | Conventional Kale | Organic Kale |
|---|---|---|
| Pesticide Use | Uses synthetic pesticides, including some identified as potential carcinogens. | Uses natural-sourced pesticides; not 100% pesticide-free, but significantly lower risk of synthetic residues. |
| EWG Classification | Considered part of the 'Dirty Dozen' list due to higher pesticide residue levels. | Considered a cleaner option with minimal to no pesticide residue detected in tests. |
| Nutritional Profile | Generally high in nutrients, but some studies indicate potentially slightly lower nutrient content than organic. | Some studies suggest higher levels of protein, fiber, and certain minerals compared to conventional. |
| Cost | Typically more affordable and widely available in most supermarkets. | More expensive due to stricter farming regulations and smaller-scale production. |
| Taste | Can sometimes have a slightly more bitter taste than organic, although other factors like variety and harvesting time play a role. | Often perceived as having a milder, less bitter flavor. |
Your Strategy for Clean Kale
Whether you opt for organic or conventional, properly washing your kale is crucial for reducing exposure to dirt, bacteria, and residual pesticides. Simply rinsing under cold water is not enough, especially for crinkly, textured leaves.
How to Wash Kale Effectively
- Prepare the leaves: First, separate the leaves from the tough, central stems, as these can harbor extra dirt. Tear the leaves into bite-sized pieces for easier cleaning.
- Soak in a solution: Fill a large bowl, basin, or clean salad spinner with cool water. For a more effective clean, add a simple solution. One effective method is using baking soda: mix about a teaspoon of baking soda per two cups of water. Alternatively, a 10% saltwater solution has also been shown to be effective.
- Agitate and soak: Submerge the kale leaves and gently swish them around with your hands for a minute or two to loosen dirt and debris trapped in the folds. Let the kale soak for at least 10-15 minutes.
- Rinse thoroughly: After soaking, lift the kale out of the solution into a colander, allowing any sediment to remain at the bottom of the bowl. Rinse the kale again under fresh, cool running water to remove any lingering washing solution.
- Dry completely: Excess moisture can cause kale to spoil quickly. Use a salad spinner or lay the leaves on a clean kitchen towel to pat them completely dry before cooking or storing.
Don't Let Pesticides Deter You from Eating Kale
Despite its place on the Dirty Dozen, the health benefits of kale are well-documented. It is an excellent source of vitamins K, A, and C, as well as antioxidants and fiber. The health advantages of consuming any vegetable far outweigh the minimal risks associated with residual pesticide levels in conventional produce, as stated by groups like the Alliance for Food and Farming. For budget-conscious shoppers, a thorough wash of conventional kale is a very effective way to minimize pesticide residue, and even just rinsing with plain water is better than nothing at all. The most important takeaway is to prioritize eating more fruits and vegetables, regardless of whether they are organic or conventional.
Food Revolution Network offers more detailed guidance on effective vegetable washing techniques.
