Probabilistic Exposure Assessment to Phycotoxins by Recreational Shellfish Harvesters: Results and Influence of Shellfish Species and the Cooking Process

Phycotoxins, secondary phytoplankton metabolites, are considered as an important food safety issue because of their accumulation by shellfish until they becoming unfit for human consumption. However, the likely intakes of phycotoxins via shellfish consumption are almost unknown. The aim of this study is to assess both acute and chronic exposure levels to phycotoxins for high shellfish consumers (i.e. recreational shellfish harvesters), to develop a realistic probabilistic exposure assessment model, and to evaluate the influence of shellfish species and cooking process on exposure levels. Exposure assessment requires data on shellfish consumption and contamination. Two one-year surveys were conducted (by the same population, from the same geographical area) to assess shellfish consumption and shellfish contamination by major toxins (Domoic Acid group (DAs), Okadaic Acid group (OAs) and Spirolides (SPXs)) (Picot, Evaluation du risque lie a l’exposition aux phycotoxines via la consommation de coquillages chez les pecheurs a pied du Finistere, Ph.D. thesis, Universite de Bretagne Occidentale, Brest, France, 2010). These two kinds of data were combined with a probabilistic MCMC (Markov-Chain, Monte-Carlo) method. Assessments were made for both acute and chronic-exposures considering the impact of shellfish species and cooking on phycotoxin levels. For acute exposures, according to the shellfish species considered, the mean exposure levels ranged from 20 to 740; from 3.8 to 702; and from 0.7 to 78.4 ng/kg pc, for DAs, OAs and SPXs, respectively. Results reveal inter-species variabilities have a considerable impact on exposure levels and consequently should be considered to choose the monitored species in monitoring programs. Concerning chronic exposures, mean exposures were equal to 110; 54 and 5.4 ng/kg pc/day for DAs, OAs and SPXs, respectively. The impact of cooking differs according to the phycotoxin. For lipophilic toxins, the cooking increased the exposure by a factor about 1.5–2. For DAs, considering the cooking process, the exposures decreased for cockles and razor clams but increased for mussels, donax and hard shell clams. Thus, the actual banning levels based on raw bivalves might over or under protect the consumers when they cooked shellfish.