Some popular brands of facial creams that are advertised as containing "activated carbon" for better results can be harmful to the skin and even cause death, scientists say.
Application of such face creams may bring quick results and prolonged use could be disastrous, warns a study by researchers at the Indian Institute of Engineering Science and Technology (IIEST) at Howrah in West Bengal,
The study, published in the "Applied Nanoscience" journal, was partly funded by the central government's Department of Science and Technology.
The researchers say they found the active micro-carbon used in these face creams to contain nanosized particles called "reduced graphene oxide (rGO)".
Under exposure to visible light, rGOs get activated by oxygen in the air to generate reactive oxygen species (ROS) harmful to skin, says the report. "The common effects of ROS are cancer, cell proliferation and aging."
"Such face creams are potential cancer-creating agents," Sabyasachi Sarkar, chemistry professor at the Institute and lead author of the report, told this correspondent in an email. "The irony is our film stars and players advertise them without knowing that they are promoting death."
Activated carbon powder (also called activated charcoal) has long been in use in the purification of water, as an air filter and in adsorbing pesticides and other harmful substances. However, its use in facial cream formulations -- supposedly to combat dark-spots, acne, oily skin and for getting a fairer skin -- is a recent development, says the report.
"The common side-effect of any face cream is itching, allergy, dry skin, pimples or photosensitivity," the authors say. "However, the use of micro-carbon in facial creams poses extra problem as it contains a fair proportion of rGO."
Using state-of-the-art microscopic and spectroscopic techniques the researchers investigated the presence of micro-carbon in three popular brands and noticed the presence of spherical nano-carbon in some samples and graphene-like sheets in other samples.
For studying the toxic effect of rGO, the scientists incubated human skin cells with rGO dilutions for12 hours under a 200-watt light source and found that the isolated rGO has a "cytotoxic" effect on these cells.
The results indicate that the active micro-carbon used in facial cream contains enough graphene material like rGO, which has high cytotoxic effect, says the report.
"The rGO present in micro-carbon remains dormant but gets aggravated under normal light and through oxygen in the air, converts to a toxic super-oxide anion. The superoxide anion is the first member of the ROS which will have a cascading damaging effect on living cells and would mutate the normal facial cells readily," the report says.
The study concludes that manufacturers of such facial creams "should ensure that the micro-carbon that they use should not contain nanocarbon-like rGO".
(KS Jayaraman is a senior journalist who writes on scientific issues. He can be contacted at firstname.lastname@example.org)