in the research paper there is a math:

"The FDA recommended maximum DIV for aspartame for humans is 50 mg/kg (33). Based on allometric conversion utilizing pharmacokinetic and body surface area parameters (43), the mouse equivalent of the human DIV is 615 mg/kg/d. Therefore, the male mice received a daily aspartame dose equivalent to 14.0%, 7.0%, and 3.5% of the FDA recommended human DIV, and the females received a dose equivalent to 15.5%, 7.7%, and 3.9% of the human DIV. The estimated average daily aspartame intake in humans is 4.1 mg/kg (44), corresponding to a mouse equivalent dose of 50.68 mg/kg (43), which was the dose delivered to mice consuming 0.015% aspartame."

The "mouse equivalent dose" calculated by this paper:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4804402/

- Larger animals have lower metabolic rates

- Physiological process of larger animals is slower

- Larger animals required smaller drug dose on weight basis