A new study that links the artificial sweetener Splenda to a higher risk of leukemia is under scrutiny.

The study, conducted in Italy and published in January in the International Journal of Occupational and Environmental Health, found a connection between large doses of sucralose and a significant increase in the incidence of malignant tumors in mice.

Splenda is the commercial name for a sucralose-based product. According to UPI, Splenda was introduced in 1999 as a healthier alternative sweetener option.

Critics of the new study claim that the mice were given a mass amount of Splenda, the equivalent of a person consuming 10 diet sodas per day.

Splenda defended the safety of its product in a press release, claiming sucralose has been the subject of more than 110 studies over a 20-year period, and the studies have found no link between sucralose and cancer.

While the study’s authors write that further studies are necessary to confirm the link, they conclude, “Considering that millions of people are likely exposed, follow-up studies are urgent.”