WHO declares aspartame "possibly carcinogenic." Here's what to know about the artificial sweetener.

The World Health Organization has declared aspartame, a common artificial sweetener used in thousands of products, to be "possibly carcinogenic to humans" — while also noting that "safety is not a major concern" in the quantities people would normally consume.

WHO's International Agency for Research on Cancer, or IARC, categorized the sweetener in Group 2B on the basis of "limited evidence for cancer in humans," specifically for hepatocellular carcinoma, a type of liver cancer, according to a news release.

"Cancer is one of the leading causes of death globally. Every year, 1 in 6 people die from cancer. Science is continuously expanding to assess the possible initiating or facilitating factors of cancer, in the hope of reducing these numbers and the human toll," Dr. Francesco Branca, director of the department of nutrition and food safety at WHO, said in a statement Thursday. "The assessments of aspartame have indicated that, while safety is not a major concern at the doses which are commonly used, potential effects have been described that need to be investigated by more and better studies."