The Environmental Working Group has released their most recent report on the presence of pesticides in foods. The study found 70% of conventional produce contaminated with pesticides even after washing. Strawberries, kale, and spinach were among the most contaminated foods. Analysis of kale found 92% of samples had two or more pesticide contaminants.
A single sample could have up to 18 different pesticides. It is important to realize that pesticides are most often tested individually for toxicity. Interactions between pesticides have rarely been examined. "Dacthal – the most common pesticide found, which was detected in nearly 60% of kale samples, is banned in Europe and classified as a possible human carcinogen in the US."