In agricultural valleys of coastal areas of Sinaloa State, Mexico, intensive agriculture has been developed with a high input of agrochemicals, particularly pesticides. This has resulted in an increase of coastal water pollution, which receives discharges from agricultural drains, channels, etc. Consequently, seafood extracted from these water bodies does not guarantee the safety required for human consumption. Therefore, during the dry and rainy seasons, February–June 2022 and July–September 2023 respectively, the amount and type of pesticides and coliform bacteria in water, sediments, as well as in clams and oysters (Anadara spp., Crassostrea, spp.) were evaluated in Altata bay and Ceuta bay, located in central part of Sinaloa, since they receive discharges from the agricultural valleys of Navolato and Culiacán; In addition, some pathogenic bacteria, such as Salmonella Spp., Vibrio ssp., etc., were determined to know the risk of mollusks consumption. Results indicated that pesticide pollution was from moderate to very high. Methoxychlor was the most frequent pesticide found, with values up to 509.607 μg/g-oyster tissue and 39.79 μg/L of water. The fecal coliform values in water ranged from 28 NMP/100 ml in March 2022 to 3609 NMP/100 ml in August 2023, while the total coliforms in mollusks were 136 NMP/g-tissue in clams in March, up to 9600 NMP/g in oysters in September, exceeding the permissible levels established in Mexican normativity. In some bivalve samples, pathogenic bacteria were found, such as Enterobacter agglomerans, Klebsiella pneumoniae, Vibrio alginolyticus, Aeromonas caviae, Listonella anguillarum, Pseudomonas mendocina, Pseudomonas aeruginosa, and Acinetobacter iwoffi. Finally, to reduce the pollutants amount in mollusks, a simple system was implemented, placing the mollusks in aquariums and using a pump (which circulates the aquariums water through filters), and small amounts of chlorine were added as a bactericidal agent. This treatment, by three weeks, decreased between 40% to 70% of the pesticides and coliform bacteria, respectively, improving the safety degree of mollusks and then risk to public health.
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