P22 | Marketing practices for bivalve mollusks in the Campania Region: between legal compliance and tradition

The production and marketing of filter-feeding bivalve mollusks are subject to European regulations aimed at ensuring a high level of consumer protection. Among the various instructions, it is clearly prohibited to immerse and/or spray the products with water once they are packaged for retail sale and have left the shipping center. Despite this, in the province of Naples, it is easy to find mollusks for sale immersed in tubs containing water, often taken from near the coast or in ports, increasing the risk of causing harmful effects on public health. Some operators, driven by market demand and the need to comply with European regulations, are requesting authorization as CSMs, even tho the volume of product they handle remains that of a retailer. The purpose of this study is to assess the risk following the ingestion of a product re-immersed in water during the retail phase. Over the three-year period 2023-2025, a total of 33 samples of bivalve mollusks, each consisting of 5 individuals (20 Chamelea gallina, 13 Tapes semidecussatus), and 33 samples of re-immersion water were analyzed. These samples were collected by the NAS Unit of Naples from fishmongers and shipping centers located in the province of Naples. Analyzes performed on mollusks: detection of Salmonella spp. and enumeration of Escherichia coli (EU Regulation 2005/2073 and subsequent amendments); on water samples: Escherichia coli and Total Coliforms, (UNI EN ISO 9308-2:2014). The results obtained showed that 1 sample of Chamelea gallina and 2 of Tapes semidecussatus were non-compliant due to the presence of E. coli exceeding legal limits, and furthermore, 2 samples of Tapes semidecussatus were respectively non-compliant due to the presence of E. coli and Salmonella spp. in one unit of consumption, and due to the presence of Salmonella spp. in 3 units of consumption. Regarding the water samples: 11 out of 33 samples had levels exceeding 150 MPN/100 ml for E. coli, and 25 out of 33 samples had levels exceeding 150 MPN/100 ml for Coliforms. In order to get an indication of the trend of the parameters under study, correlated with the sample size, we transformed the E. coli values into natural logarithms. This allowed us to infer a "threshold effect," according to which, with E. coli concentration levels in the water < 4 log units, the possibility of shellfish contamination remains negligible. On the contrary, once that threshold is exceeded (4–5 logs, or 50–150 MPN/100ml), the mollusks begin to accumulate bacteria more quickly. Therefore, it is easy to deduce that this situation, combined with rising ambient temperatures, can favor bacterial replication, increasing the risk of consumers being exposed to food that could be a vehicle for pathogens. It is therefore necessary to take concrete action against operators to discourage the use of this practice, while at the same time adequately informing consumers so they can make an informed choice when purchasing bivalve mollusks. On the other hand, this data allows us to make a preliminary reflection on the possibility of regulating a potential option to re-immerse mollusks, considering the implementation of the concept of regulatory flexibility. In this way, this practice could be regulated in detail, for example by relying solely on the use of clean seawater/salt water, as is already authorized in other sectors.