Exposure assessment of ochratoxin a using paired serum and 24-hour pooled urine samples from Japanese adults

Ochratoxin A (OTA) is a mycotoxin produced by <i>Aspergillus</i> and <i>Penicillium</i> species, contaminating various food products. This study aimed to characterise OTA exposure in Japanese adults by analysing serum and urinary concentrations, evaluating demographic differences, and comparing these findings with international biomonitoring data. Serum and 24-h pooled urine samples were collected from 69 individuals, including 34 males and 35 females. OTA concentration in serum and urine were measured using a validated liquid chromatography-tandem mass spectrometry method. Detection frequencies for OTA above the limit of detection (10.0 ng/L for serum and 7.0 ng/L for urine) were 100% in serum and 55% in urine. The median concentrations (95th percentile) of OTA in serum and urine were 81.5 ng/L (177.4 ng/L) and 7.3 ng/L (15.5 ng/L), respectively. These concentrations were comparable to or lower than those reported in other countries. Additionally, the estimated probable daily intake values calculated using OTA concentrations in serum and urine were one to two orders of magnitude lower than the tolerable daily intake levels for OTA. This study represents the first comprehensive assessment for serum and urinary OTA level in Japanese adults. The findings provide valuable insights into dietary OTA exposure in Japan and contribute to a better understanding of OTA contamination in the context of food safety.