Chemical fertilizers and pesticides if consumed by humans are known to be harmful to human health.
It is widely accepted that fruits with thin skins and vegetables are more likely to contain higher pesticide content when compared to thicker skin fruit. Thus, thin-skinned fruits like apples, strawberries, peaches, blueberries, nectarines, grapes, cherries, and mangoes are high pesticide vulnerable fruits. Among vegetables, we have cucumbers, spinach, bell peppers, potatoes, lettuce, celery, etc.
Fruits with thicker skins like banana, pineapple, kiwi, cantaloupe are likely to be more secure from pesticide excess load. Vegetables less likely to suffer from pesticides include asparagus, broccoli, onions, cabbage, and sweet corn.
How much pesticides are found in thin-skinned fruit can be understood by the example of conventionally grown apples?
According to the US Environmental Working Group’s evaluation of USDA information, pesticides appear in most of the samples tested. Up to 48 different pesticides have been identified in tested apple samples. This was true for both US and imported apples.
Apple has been placed, for several years in a row, at the top of the list of most contaminated crops in the US by the Washington based non–government organization Environmental Working Group (EWG). Other fruits and vegetables that regularly find a place in the topmost contaminated crops, named popularly as the Dirty Dozen, include peaches, nectarines, strawberries, grapes, celery, spinach, sweet bell peppers, cucumbers, cherry tomatoes, snap peas, and potatoes.
Pesticides get deposited, on the apple trees leaves, shoots, fruits, and branches, in the process of pesticide spraying. The concave depression where the apple fruit is attached to the branch aids the pesticide to seep through the skin into the core of the fruit.
Peeling the skin of the apple fruit would remove most of the pesticide that is deposited on the skin. But this leads to substantial nutrient loss. According to the USDA National Nutrient Database, an unpeeled apple has nearly double the fiber, 25% more potassium, and 40% more Vitamin A and other vitamins. Apple peels also contain the bioactive compounds polyphenols, pectins, and ursolic acid. These compounds have been observed to help the body defend itself from many ailments.
The pesticides contaminating apples include Thiabendazole that has carcinogenic property, Pyrimethanil — a suspected hormone disrupter that could potentially cause neurological and reproductive effects, Phosmet a neurotoxin, Myclobutanil, and Diazinon which are reproductive toxins. The level of pesticides in organic apples, when compared to conventional apples, is negligible.
Organic eating concepts are fairly well studied and there is a substantial body of literature available on the subject. In summary, though, I would recommend that it is best to buy thin-skinned organic fruits and vegetables to avoid adverse health impacts of pesticides and chemical fertilizer.
You can know more about organic foods here.