An initial estimate of the toxicity of CYN in 1985 was that an  at 24 hours was 64±5 mg of freeze-dried culture/kg of mouse body weight on intraperitoneal injection. A further experiment in 1997 measured the LD as 52 mg/kg at 24 hours and 32 mg/kg at 7 days, however the data suggested that another toxic compound was present in the isolate of sonicated cells used; predictions made by Ohtani et al. about the 24‑hour toxicity were considerably higher, and it was proposed that another metabolite was present to account for the relatively low 24‑hour toxicity level measured.
Because the most likely human route of uptake of CYN is ingestion, oral toxicity experiments were conducted on mice. The oral LD was found to be 4.4-6.9 mg CYN/kg, and in addition to some ulceration of the oesophageal gastric mucosa, symptoms were consistent with that of intraperitoneal dosing. Stomach contents included culture material, which indicated that these LD figures might be overestimated.
Another means of exposure to CYN is related to alterations in the gut microbiome by artificial sweetners. A study including Aspartame conducted at Cedars-Sinai in Los Angeles by Ruchi Mathur, MD detected CYN in the duodenum at levels four times above baseline in Aspartame users, along with alterations in bacterial species.