Understanding Hydroquinone

Everyone desires to look and feel beautiful. Globally, beauty has been associated with fair and light skin tones. As a result, there has been a boom in the beauty industry especially for products that promise to give skin radiance, decrease fine lines and wrinkles, and reduce skin pigments to achieve fairer skin.

The demand for skin lightening products has risen sharply, especially in Asian countries such as China, India, Japan, Korea, Indonesia, and Vietnam. According to a new research report by Future Market Insights titled “Skin Lightening Products Market: Opportunity Assessment 2017-2027”, the global skin lightening products market is expected to reach a valuation of over US$ 24 Bn by the end of 2027.

One very common ingredient in these skin lightening products is hydroquinone. Hydroquinone is a chemical found in tea, wheat, berries, beer and coffee that has bleaching properties. It has rather important industrial applications, as it is used in developing black-and-white photographs, in the rubber production processes and to inhibit polymerization in industrial processes. In 1936, hydroquinone was first found to have bleaching properties and slowly made its way into over-the-counter skin-lighteners from the 1960s. Lately, there have been concerns raised over hydroquinone’s safety to humans due to its potential cancer-causing properties and other side effects. Several countries such as Japan, Australia, and the European Union have banned the use of hydroquinone in cosmetics while the FDA in the United States considers it a GRASE (generally regarded as safe and effective) ingredient. The FDA has acknowledged that hydroquinone causes ochronosis and is potentially carcinogenic with a proposal to remove it off the GRASE list; however, changes are slow to take effect.

How does it work?

Hydroquinone has historically been prescribed by doctors to treat hyperpigmentation or excessively dark skin. 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 melanin pigment. By stopping more pigment from forming, it lightens skin.

Why the fuss?

If it is this magical chemical that can lighten skin, why are people concerned about it? Firstly, hydroquinone is known to be toxic to land animals as documented in many scientific toxicology studies. 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 the 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, typically thicker and scaly. This disease, known as ochronosis is a serious side effect of hydroquinone and is very difficult to treat. Ochronosis is best treated by completely stopping the use of hydroquinone and allowing the skin to heal over time. Recent research has shown successful uses of CO2 or alexandrite lasers to treat ochronosis.

What do studies say?

Some scientists and doctors have since been protesting against the use of hydroquinone in cosmetics. A recent study published in 1998 in the Journal of Toxicology and Environmental Health 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. Researchers found that hydroquinone is quickly absorbed into the skin and within an hour, it 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.

Summing it up:

With increased scientific evidence on the toxicology of hydroquinone, many developed countries have taken the step to ban its use in over-the-counter cosmetics. If you live somewhere that does allow hydroquinone, you must remember that it can have serious adverse long-term effects, especially for those with darker skin tones. If you happen to use them, always do so under the supervision of a medical professional. To achieve the results of lightening skin, there are now more alternative ingredients worth learning such as Arbutin, Dong Qua Extract, and Turmeric, just to name a few. As always, we recommend you to stay informed!

References:

  • Sang Yeul Lee, Namhuk Baek & Tae-gyu Nam (2016) Natural, semisynthetic and synthetic tyrosinase inhibitors, Journal of Enzyme Inhibition and Medicinal Chemistry, 31:1, 1-13, DOI: 10.3109/14756366.2015.1004058
  • Ronald C. Wester Joseph Melendres Xiaoying Hui Rebecca Cox Steffany Serranzana Hongbo Zhai Danyi Quan Howard I. Maibach (1998) HUMAN IN VIVO AND IN VITRO HYDROQUINONE TOPICAL BIOAVAILABILITY, METABOLISM, AND DISPOSITION, Journal of Toxicology and Environmental Health, Part A, 54:4, 301-317, DOI: 10.1080/009841098158863
  • Journal of American Academy of Dermatology, June 1982Volume 6, Issue 6, Pages 1092–1093
  • Tsz Wah Tse (2010) Hydroquinone for skin lightening: Safety profile, duration of use and when should we stop?, Journal of Dermatological Treatment, 21:5, 272-275, DOI: 10.3109/09546630903341945
  • Lidia Zapór (2004) Toxicity of Some Phenolic Derivatives—In Vitro Studies, International Journal of Occupational Safety and Ergonomics, 10:4, 319-331, DOI: 10.1080/10803548.2004.11076620