More on the subject:

'Whiter skin in 14 days': Tracking the illegal sale of skin-whitening creams in Canada

Testing the products

After purchasing more than 100 products used for skin lightening or whitening, Marketplace commissioned a laboratory in the U.K. to test more than a dozen of the most popular ones, looking for some common ingredients, including: 

• Hydroquinone, used to lighten dark spots or uneven skin tone. Health Canada warns concentrations of two per cent and higher can cause severe skin issues, such as burning and discolouration. It has also been linked to an increased risk of cancer.

• Mercury, sometimes added to stop the production of melanin, or pigment, is a heavy metal that can pose serious health risks. In addition to skin rashes and scarring, adverse side effects can include mercury poisoning, muscle atrophy, kidney damage and neuropathy — a disease of the nervous system. 

• Topical corticosteroids are highly potent prescription drugs not authorized for sale in Canada without a doctor's prescription. Side effects include skin irritation and, with prolonged use, skin weakening or deterioration, as well as decreased ability to fight infection, symptoms of adrenal gland suppression, or Cushing syndrome.

Toronto dermatologist Dr. Lisa Kellett has seen the damage skin-lightening creams can cause firsthand, treating patients who come into her office with skin issues after using these over-the-counter products.

"The worst I've seen would be infection causing scarring. I've seen ochronosis, which is pigment change," she said, referring to the blue, grey or black discolouration that can occur after long-term use of hydroquinone.