The Dark Side of Sunscreen
The chemical - known as OMC - is found in more than 90 percent of
sunscreen products and filters out damaging ultraviolet rays. But
scientists at the Norwegian Radiation Protection Authority found when
they combined OMC and simulated sunlight in the lab, it killed animal
"We started this study to find out whether sunscreens were more
or less stable after longtime radiation with sunlight," says Terje
Christensen, professor and biophysicist with the authority. Instead,
they found OMC might do more harm than good.
The team took mouse cells, placed them in an ethyl alcohol
solution and added five parts per million of OMC, a lower concentration
than found in most sunscreens. Half the cells died. They then exposed
the cells to two hours of simulated midday light and found more cells
dying. Those cells soaking in a non-OMC solution were alive and well.
is a very efficient UV filter, it's the most important ingredient you
have in the sunscreen," Christensen says. But when combined with light,
the byproduct is roughly twice as toxic as OMC on its own.
"We see two types of toxicity," says Christensen. "We can
observe necrosis, where the outer cell membrane is disrupted, and
becomes less efficient as a barrier. And we can see apoptosis - or
programmed cell death - where cells that are damaged by certain
substances, will decide by themselves to die; a sort of suicide."
But giving up sunscreen is not the answer, says Dr. Barbara
Gilchrest, professor and chair of dermatology at Boston University
School of Medicine.
"The fact that it (OMC) may or may not be toxic when placed
directly on living cells, seems to me to be quite irrelevant to its
effectiveness as a sunscreen ingredient. It's put outside the skin on
the dead outer layer of surface, and almost certainly does not
penetrate the skin, at least not to any significant degree," she
"I would strongly caution against extrapolating from a cell
culture experiment to a clinical-use situation, and I would certainly
continue to recommend to my patients that they use sunscreens
regularly, including sunscreens with octyl methoxycinnamate in it," she
What To Do
Christensen says he's not telling people to
stop using sunscreens; he's just urging them to use other protections.
"There are some unknown effects going on, and this is a small alarm
bell," he says.
The American Cancer Society estimates more than 1 million cases
of skin cancer will be diagnosed this year, and about 10,000 people
will die of this cancer.