Where's the problem?
In Germany usually the peel of Citrus aurantium and Citrus medica is used to produce finest candid citrus peel, used in finest Christmas bakery.... Typical for "Nuernberger Lebkuchen" and the famous "Christstollen" to contain much of it.
Kumquats are eaten whole and Johann Volkamer, a famous german Citrus specialist around the beginning of the 18. century report on eating all citrus fruits whole.
So candied peel usually was made and enjoyed...
So even fresh peel can be used, to aromise finest dishes and bakery. Eat it, may the fralvour is sour and bitter, but it isn't harmfull and non-toxic to humans.
So if you didn't used pesticides, well, it's all a question of taste....
Consider: even finest cocktails contain often whole fruit, simply squeezed or rammed by hand to squeeze out juice and peel oils....
So enjoy!
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Eerh, hmm, uuuh, oooh, just guessing