Bergamot essential oil and furanocoumarins. The main compounds in the oil are limonene, linalyl acetate, linalool, γ-terpinene and β-pinene, and in smaller quantities geranial and β-bisabolene. The main non-volatile compounds are coumarins (citropten, 5-geranyloxy-7-methoxycoumarin) and furanocoumarins (bergapten, bergamottin). The bergamot essential oil is particularly subject to adulteration being an essential oil produced in relatively small quantities. Generally adulteration is to "cut" the oil, i.e. adding distilled essences of poor quality and low cost, for example of bitter orange and bergamot mint and/or mixtures of terpenes, natural or synthetic, or "reconstruct" the essence from synthetic chemicals, coloring it with chlorophyll. Worldwide, each year, around
Bergamot orange skin of guinea pigs was shown to have a concentration-dependent phototoxic effect of increasing redness after exposure to ultraviolet light (due to the chemical bergapten, and possibly also citropten, bergamottin, geranial, and neral). This is a property shared by many other citrus fruits. Bergapten has also been implicated as a potassium channel blocker; in one case study, a patient who consumed four litres of Earl Grey tea per day (which contains bergamot essential oil as a flavouring) suffered muscle cramps. Bergamot is also a source of bergamottin which, along with the chemically related compound 6',7'-dihydroxybergamottin, is believed to be responsible