Occurrence and Dietary Exposure of PFAS in Singapore: Insights from a Total Diet Study

Per- and poly-fluoroalkyl substances (PFAS) are synthetic compounds known for their environmental persistence, bioaccumulation, and adverse human risks. This study presents Singapore's first Total Diet Study assessing the occurrence and dietary exposure of four PFAS, with 503 pooled samples analysed across 23 categories of commonly consumed food prepared using representative cooking methods. The majority (75%) of the food categories had non-detectable levels. Fish and seafood accounted for 89.7% of detections, with frequencies in decreasing order of PFOS > PFOA > PFNA > PFHxS, and an overall mean concentration of 0.67 µg/kg. As 93% of results are left-censored, dietary exposure assessment using a lower bound approach (LB) identified clams and crabs as having a higher estimated exposure risk for consumers, exceeding the EFSA's Health-Based Guidance Value of 0.63 ng/kg bw/day by factors of 4.8 and 1.9, respectively. PFAS LB dietary exposure for the general population was estimated at 3.1 × 10^-3 ng/kg bw/day (average) and 1.7 × 10^-1 ng/kg bw/day (95th percentile), indicating a low risk to the population. However, the limit of quantification of 0.1 μg/kg requires improvement to reduce left-censored data and improve dietary estimates. Further research including a broader range of PFAS compounds is recommended for high-risk food categories to increase the accuracy of exposure assessments.