A Review of the Fate and Effects of Selected Low- and No-Calorie Sweeteners and Their Probabilistic Risk to Aquatic Organisms

Low- and no-calorie sweeteners (LNCS) are increasingly prevalent in food and beverages, with significant consumption growth in recent decades. This trend has led to heightened research into monitoring these non-nutritive sugar substitutes in environmental matrices, especially surface water. Many LNCS are excreted largely unchanged and are highly soluble in water, resulting in their detection in aquatic environments at concentrations ranging from ng/L to µg/L, primarily due to municipal or household wastewater discharge. While LNCS are generally considered safe for human consumption with established Acceptable Daily Intakes (ADI), their ecological risks remain an interest due to their global ubiquitous use, eventual entry into surface waters, and limited use of contemporary ecological risk assessment methodologies for these substances. We investigated five common LNCS: aspartame (ASP), cyclamate (CYC), saccharin (SAC), sucralose (SUC), and steviol glycosides (SG), an emerging natural sweetener. Utilizing data from Euromonitor International, we assessed global consumption patterns in food and beverages and generated probabilistic exposure distributions using models for the U.S. (iSTREEM®) and Europe (HydroFATE). These were compared to retrospective exposure values based on 75 curated aquatic concentration monitoring studies spanning the world. A relative exposure index was created to contextualize modeled results globally across seven regions. We integrated comprehensive aquatic ecotoxicity data from 54 additional studies with our exposure assessments for a probabilistic ecological risk evaluation. Predicted no-effect concentration (PNEC) values were established for ASP (68.8 µg/L), CYC (20-20,000 µg/L), SAC (2,000 µg/L), SG (10,000 µg/L), and SUC (9,300 µg/L). These PNECs were significantly higher than predicted environmental concentrations and observed data by one to four orders of magnitude, depending on the LNCS and exposure scenario. This suggests high margins of safety and minimal ecological risk at current usage levels. Routine updates of this risk assessment are recommended to maintain on-going aquatic safety as LNCS usage evolves.