The World Health Organization (WHO) classified aspartame, a low-calorie artificial sweetener often added to soft drinks like Diet Coke, as a possible carcinogen Thursday evening.

The WHO’s International Agency for Research on Cancer (IARC), citing “limited evidence” for carcinogenicity in humans, classified aspartame as possibly carcinogenic, a ruling that was reaffirmed by the Joint Expert Committee on Food Additives (JECFA). 

IARC and JECFA stated that they conducted separate, independent analyses about the potential carcinogenic hazard related to aspartame, which was invented in 1965 and has been regularly incorporated into foods and drinks since the early 1980s. 

JECFA added that the evaluated data indicated there is “no sufficient reason” to change the established acceptable daily intake of 0-40 mg/kg body weight for aspartame.

The decision, which was leaked to Reuters late last month, marked a first step by the IARC to understand the carcinogenicity of an agent, but does not reflect “the risk of developing cancer at a given exposure level,” the WHO noted.

“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,” said Dr. Francesco Branca, director of the department of nutrition and food safety at the WHO, in a statement.

Aspartame has been a controversial compound in health and food research for years despite several reviews by the Food and Drug Administration, the Centers for Disease Control and Prevention as well as other international health and food regulators that have cleared it of major health risks.

In a statement to The New York Times, the FDA said it “disagrees with IARC’s conclusion that these studies support classifying aspartame as a possible carcinogen to humans.”

The classification also received pushback from beverage manufacturers and representatives from their trade associations.

PepsiCo CFO Hugh Johnston told Reuters on Thursday that the company does not intend to change its use of aspartame. Though the company’s stock was trading slightly higher during the early Thursday morning session, The Coca-Cola Company’s stock was trading slightly lower.

The interim president and CEO of American Beverage Kevin Keane stated that aspartame is “safe” and that the WHO’s rulings reinforce the position of the FDA and international food safety agencies regarding the compound’s health effects. 

Meanwhile, the Calorie Control Council, an international association representing the low-calorie food and beverage industry, issued a statement after the WHO unveiled its decision and 

“Consumers have a strong desire for reliable and science-based information and JECFA’s review reaffirms the overwhelming body of evidence that confirms aspartame is safe,” Calorie Control Council president Robert Rankin stated. “To assert otherwise is misleading, inaccurate, and fearmongering to the nearly 540 million people globally living with diabetes and millions of others managing their body weight who rely on and/or chose products that contain low- and no-calorie sweeteners such as aspartame.”