OBJECTIVETo establish the indexes and weights of risk assessment of shellfish poisoning outbreak caused by red tide.

METHODSThe risk assessment indexes were developed with the methods of literature review, brainstorm and expert consultation, and the weights of indexes were calculated by the method of analytic hierarchy process. The established indexes contained the risk possibility, impacts of public health, population vulnerability and resilience. The relative risk indexes(integrated risk indexes) of different shellfish poisoning were computed by combining hierarchy process and TOPSIS methods. Moreover, the weights of indexes were further used to generate absolute risk values by multiplying indexes.

RESULTSFour primary indexes and 17 secondary indexes were identified for risk assessment of shellfish poisoning outbreak. Of 17 secondary indexes, the knowing rate of shellfish poisoning, medical accessibility, the number of people being affected, laboratory testing capacity and the habits of eating seafood of local residents had relatively large weights (0.0876, 0.0840, 0.0716, 0.0703 and 0.0644, respectively), which accounted for nearly 38% of the total weight. All consistency ratio (CR) were less than 0.1. The index system was applied in Cangnan county of Zhejiang province. The results showed the relative risk indexes of paralytic shellfish poisoning (PSP), diarrhetic shellfish poisoning (DSP), neurotoxic shellfish poisoning (NSP) and amnesic shellfish poisoning (ASP) were 0.4526, 0.7116, 0.1657 and 0.2884, and the absolute risk values were 0.2542, 0.2668, 0.1907 and 0.2184, respectively. The risk orders of the 4 kinds of shellfish poisoning sorted by relative risk indexes and absolute risk values were consistent.

CONCLUSIONSThe indexes and weights of risk assessment of shellfish poisoning outbreak caused by red tide are established, which can provide scientific advice for prevention and control of shellfish poisoning outbreak.