Skin care product manufacturers all over the U.S. and Canada use hydroquinone. Product upon product contains it as the active ingredient to lighten skin, or combine it with alpha hydroxy acids to exfoliate top layer (and dead) cells while bleaching pigmentation. For over forty years, vendors have sung its praises as being superior to metols for lightening pigment because it’s less likely to cause side effects like dermatitis.
What all those manufacturers won’t tell you is that their active ingredient darling is banned in the EU and Africa. They also won’t tell you that the Federal Food and Drug Administration revoked its approval of hydroquinone in 2006 and proposed further intensive study of the substance for human use. A ban has not yet been enacted, but studies on rats have shown a carcinogenic potential for the chemical. Because it leaches into the human body through the skin, the cancer-causing potential cannot be ignored.
This weakly acidic chemical is a phenol (naturally or synthesized compounds similar to alcohols, but more acidic). One of the first uses of hydroquinone was coincidentally with metols to develop film negatives. It was used to change the compound silver into pure silver. It is also used in the rubber industry and in some food processing.
Aside from the fact that no one wants to use a darkroom chemical on her face, there is statistically significant data and evidence that hydroquioinine, when used in topical solutions of over 2%, and/or for sustained periods of time, can cause exogenous ochronosis (dark blue or purplish skin blotches) and skin thickening. These occurrences are often in people with darker skin tones.
The FDA recommended an NTP (National Toxicology Program) study of hydroquinone. The goal was to study the potential carcinogenic properties of the compound, both as ingested and as a topical solution. We’re not surprised by their findings— which were a lot of dead rats—most of whom were riddled with thyroid, liver, and other serious organ conditions.