Pollution analysis and dietary exposure risk assessment of lipophilic toxins in shellfish from Beibu Gulf seafood market in Guangxi Province

Lipophilic shellfish toxins are widely distributed and will be transmitted to consumers through the food chain, posing a great threat to human health. The Beibu Gulf in Guangxi Province is an important mariculture area in China, accounting for more than half of the national output. To estimate the potential dietary exposure risk of coastal residents in that area, and to provide a scientific basis for the establishment of toxin limit standards, we analyzed the contents of lipophilic shellfish toxins by liquid chromatography tandem mass spectrometry. We have used a 24-hour dietary review method to investigate the consumption of marine products by coastal residents for seven consecutive days. Then we calculated the value of estimated daily intake (ESI) of toxins in the diet by using the marine biological toxin point assessment method, and evaluated the edible safety by comparing with the acute reference dose (ARfD) recommended by the European Food Safety Agency. The proportion of samples contaminated with toxins followed a descending order of gyrodimine (GYM) (83.02%), okadaic acid (OA) (51.16%), dinophysis toxin (DTX-2)(40.91%) and homo-yessotoxin (Homo-YTX) (8.6%), with the peak values of 105.4, 31.39, 38.19 and 159.6 µg·kg⁻¹, respectively. The concentrations of toxins varied with different seasons and species. Among the six kinds of shellfish, the highest contents of OA and GYM were found in oyster samples, and the peak values were found in winter and autumn samples, respectively. The contents of DTX-2 in autumn and winter samples were significantly higher than those in spring and summer samples. Homo-YTX was only detected in scallop and mussel samples in summer and autumn. Dietary survey shows that the average daily shellfish consumption of coastal residents in Beibu Gulf was 45 g·d⁻¹. The ESI value in OA toxin was estimated to be 0.26 μg·(kg·d)⁻¹ based on the shellfish consumption and body masses of local residents, less than the ARfD value 0.3 μg·(kg·d)⁻¹ set by the European Union (EU). However, based on the shellfish consumption and body masses of local residents provided by the EU, the ESI value 0.34 μg·(kg·d)⁻¹ was higher than the ARfD value. The results suggest that although the detection rate of lipophilic shellfish toxin in shellfish samples was lower than the safe limit value set by the EU, there is a risk of dietary exposure to OA toxin for the Beibu Gulf residents.