Everyone desires to look and feel beautiful, and they have a right to feel that way too. As a result, there has been a boom in the cosmetic industry targeting people who want radiant and supple skin. However, beauty has been associated with fairer, lighter skin color, and the demand for skin-lightening products has risen sharply. One very common ingredient in these fairness products is hydroquinone.
Hydroquinone is a chemical found that has bleaching properties. It has important industrial applications, such as developing black-and-white photographs, production of rubber and inhibiting polymerization in industrial processes.
The efficacy of hydroquinone as a skin bleaching agent was discovered accidentally in 1936 during World War II, when African-American workers in rubber manufacturing factories complained of discolored areas on their hands and forearms due to exposure to hydroquinone (monobenzone). Since 1936, hydroquinone has slowly made its way into over-the-counter skin lighteners. Lately, there have been concerns raised over its safety to humans due to its potential cancer-causing properties and other side effects. Several countries have banned the use of hydroquinone in cosmetics yet in the United States, hydroquinone is available in low dose over-the-counter and in high doses with a doctor's prescription.
The inherent toxicity of hydroquinone and mercury triggered research into safer botanicals and natural or nature identical isolates that would achieve similar functional effects. Hydroquinone is known to produce serious side effects if used over a long period of time. This has led to regulations or ban on its use in several countries. For instance, in France, hydroquinone usage was first restricted to 5% and then to 2% and current European legislation prohibits its use completely in cosmetics. In the United States, the FDA has classified hydroquinone as a drug and requires a doctor’s supervision for concentration over 4%.
How hydroquinone work?
Hydroquinone has historically been prescribed to treat hyper-pigmentation, or excessively dark skin patches such as sun spots, age spots, and melasma. It stops the natural process of melanin synthesis, thereby stopping more pigment from being generated.
It works by a process known as competitive inhibition, which basically means that it acts as a blocker between the two components that must interact to make the pigment. By stopping more pigment from forming, hydroquinone lightens skin. This process takes at least three months to see visible results.
Why the fuss?
If it is this magical chemical that can lighten skin, why are people concerned about it? First, hydroquinone is known to be toxic to land animals. Even though it is less toxic to humans, it does have cancer-causing properties. Additionally, during its inhibition process, it also generates free-radicals that cause damage to skin-pigment cells and cells that generate those pigments. If that isn’t enough, the chemical can cause permanent damage to cornea and permanent pigment loss. The major reason why the damaging nature of hydroquinone came to light is because of African women. The first study that highlighted the issue was in 1982, from a doctor that noticed something strange in women who were prescribed hydroquinone.
He noticed that after years of use, doctors noticed that their cheekbones were dark and discolored compared to the rest of their skin. The texture of this skin was also different and this was quickly found to be a result of hydroquinone. The disease is ochronosis and is a serious side effect of hydroquinone that is very difficult to treat. Ochronosis has been treated with CO2 or alexandrite lasers with mixed results and by simply stopping the use of hydroquinone.
What do studies say?
Scientists and doctors have since been protesting against the use of hydroquinone in cosmetics. A recent study tried to find out how toxic hydroquinone can be to humans. The study was conducted on human volunteers as well as laboratory cultures of skin tissue. They found that hydroquinone is quickly absorbed into skin, and within an hour is circulating all through the bloodstream. They also found that it remains within the body for at least 24 hours which means that it can have adverse effects on the body in that time period.
Another study that tested specifically for the cytotoxicity of different compounds found that hydroquinone was the most toxic among those tested. It attributed the cytotoxicity to the chemical structure of hydroquinone, which included an alcohol (-OH) group.
Hydroquinone use is also reported to increase the risk of developing leukemia, liver cancer, skin irritation, irreversible hyperpigmentation and reproductive damage. The permanent depigmentation produced by hydroquinone photosensitizes the skin and makes it vulnerable to damage by UV-rays thereby increasing the risk of development of skin cancer.
Summing it up:
A lot of countries have heard the scientific evidence and banned products that have hydroquinone. In the USA, hydroquinone is available with a physician’s supervision where usage of high concentration are popular to get more “immediate” results. If you live somewhere that does allow hydroquinone, you must remember that it can have serious adverse long-term effects when misused. If you want to try hydroquinone, always do so under the supervision of a medical professional to minimize negative experiences.
In general, it is always better to avoid products with hydroquinone in them. Stay informed and safe!
HUMAN IN VIVO AND IN VITRO HYDROQUINONE TOPICAL BIOAVAILABILITY, METABOLISM, AND DISPOSITION