Shellfish contamination with lipophilic toxins and dietary exposure assessments from consumption of shellfish products in Shenzhen, China

Abstract

Lipophilic shellfish toxins (LSTs) can cause human illness and therefore represent a serious threat to public health. Shellfish are the main dietary source of LSTs, but very few studies have appraised dietary exposure to LSTs through shellfish consumption in China. We measured levels of multiple LSTs in shellfish samples sold in the principal wholesale seafood market in the southern coastal city of Shenzhen, and we estimated the potential for acute and chronic LST exposure of the Shenzhen population via ingestion of shellfish. LST contamination data were obtained from a total of 14 species of 188 commercial samples. Eleven individual LSTs, namely okadaic acid (OA), dinophysis toxin-1 and −2 (DTX1 and DTX2), pectenotoxin-2 (PTX2), yessotoxin and homo yessotoxin (YTX and hYTX), azaspiracid-1, −2 and −3 (AZA1, AZA2, AZA3), spirolides (SPXs), and gymnodimine (GYM), were determined using liquid chromatography electrospray-ionization tandem mass spectrometry (LC-ESI-MS/MS). More than two thirds of samples showed undetectable LSTs, while the detection rates (the proportion of samples with detectable LSTs) of individual LSTs ranged from 0% to 45.7%. Most shellfish samples had lower levels of LST contamination than the corresponding limits of detection (LODs), while some samples had levels of hYTX and GYM that exceeded the limits of quantification (LOQs). Overall, levels of LSTs in the 188 samples were below the regulatory limits set by most countries. Acute and chronic exposures of LST were estimated by a point-estimate modeling method that combined sample contamination data with consumption data from dietary survey of Shenzhen residents and consumption figures proposed by EFSA, the European Food Safety Authority. Seasonal variations in LST concentrations were noted in some instances. Overall, the estimated acute exposure to LSTs based on consumption of large-size shellfish portions and the maximum LSTs contamination level were below the provisional acute reference doses (ARfDs) proposed by the EFSA. Chronic exposure estimates based on mean and 99th percentile consumption of shellfish by Shenzhen residents and mean LSTs contamination levels in the collected samples were from 2452 to 74 times lower than those associated with estimated acute exposure levels.