Having said that, it is necessary to remember that the fruit peel can be a vehicle for impurities and contaminants. Most of these are deposited on the surface and very few are absorbed and then metabolized (and made harmless) by the plant itself. More specifically, among the undesirable elements that could be assumed by eating the peel of "dirty" fruit we remember: microorganisms (especially bacteria and mold), pollutants (such as, for example, the atmospheric content or that of irrigation water) and pesticides.
Although the third category is the least technically worrying, it is constantly at the centre of the attention of Italians. Pesticides (intended as anti-mycotics, pesticides, herbicides, etc.) are a category of synthetic-based products useful to ensure a certain yield in traditional agriculture. Of course, no one likes the idea that certain weeds end up on their food; however, most of the time, they are made harmless products that safeguard the food availability of fruit and vegetables. At the same time, more out of economic interest than out of consumer protection, a new set of rules has arisen that almost completely ignores the use of these synthetic pesticides: organic farming. By definition, this system significantly restricts the use of the treatments in question, which should logically be totally absent from the final product. Let's say that... that's not the case!
In Italy, the use of pesticides is strictly regulated. Even in traditional agricultural products the possible presence of treatments always falls (or at least should fall) within the safety limits imposed by law, indicating respect for the choice, quantity and timing of the correct use. At the same time (as many have already been able to verify) if it is true that organic farming denies the use of treatments, it does not guarantee that the food WILL NOT BE TRACKED. There are many reasons why such contamination should occur, often unavoidable; on the other hand, what is important is that such traces do not represent a threat to health.
Certainly there will be less honest, or just more desperate, farmers who will not risk the entire production and will use the pesticides in a less correct way; however, the controls carried out on the stored goods are always very pressing and represent an incontrovertible protection for the buyers at the end of the chain. There are also a few small exceptions. Certain types of fruit, such as citrus fruit, may undergo certain surface treatments to increase their lustre and shelf life (e.g. treatment with the fungicide imazalil). Fortunately, in our country, this event is closely linked to the obligation of a label statement: "non-edible peel" or "non-edible peel". Be careful, therefore, if you want to use orange or lemon peel for some recipe, you should always read the label to make sure you use an untreated citrus.
In conclusion, eating fruit with its peel is an excellent dietary habit with regard to the presence of dietary fiber (and not only), as long as you respect certain small precautions such as:
Consult the labels and prefer food of national origin
Always wash the fruit carefully, preferably with the use of amuchina or sodium bicarbonate.
NOTE: some conditions may require the consumption of fruit strictly deprived of its skin; this is the case of low-residue diets, prescribed for example in previous days endoscopic diagnostic investigations of the intestinal tract (eg colonoscopy), in the presence of intolerance to dietary fiber (irritable bowel syndrome) or inflammatory diseases of the colon (diverticulitis, colitis, Crohn's disease ...).
Fruit should preferably be consumed without peel even when you are not sure of the microbiological safety of the food or water used to wash it (e.g. travel to developing countries).