Total mercury and selenium levels in commercial shrimp along the Pacific coast of Mexico.

The present study analyzed the content of total mercury (THg) and selenium (Se) in the muscle of shrimp collected from local markets in the 11 Pacific coastal states of Mexico. Methylmercury (MeHg) concentration, Se:Hg ratio, health benefits value from selenium consumption (HBVSe) and the permissible weekly consumption were estimated to assess the health risk to consumers. All THg and Se concentrations were below the maximum permissible limits. All hazard quotient (HQ) values were <1, however in Hermosillo, Culiacán and Guadalajara, the Se:Hg ratio and HBVSe were <1 and negative, due to the low concentrations of Se. As a general conclusion, there is no risk nor benefit from the consumption of shrimp from the Pacific coast of Mexico due to its Hg and Se content.

Distribution and health risk assessment of Cd and Pb in two marine fishes (Haemulopsis axillaris and Diapterus peruvianus) from the Eastern Pacific.

The aim of this study was to determine the distribution of cadmium (Cd) and lead (Pb) in muscle and liver tissue of Haemulopsis axillaris and Diapterus peruvianus from the Eastern Pacific in Mexico and to assess the health risk to consumers. Fish were collected as bycatch on the continental shelf between the coasts of Sinaloa and Guerrero (Eastern Pacific). Cd and Pb were quantified in muscle and liver tissue using graphite-furnace atomic absorption spectrophotometry (GF-AAS).Concentration of Cd was greater in muscle tissue than in liver tissue; with Pb, however, the opposite pattern was found. The highest concentration of Cd (0.177 µg g-1) was found in muscle tissue of H. axillaris from Sinaloa. For Pb, the highest level (0.692 µg g-1) was found in the liver tissue of H. axillaris also from Sinaloa. Levels of Cd and Pb in muscle tissue were both below Mexican Guidelines (0.5, 1.0 µg g-1 wet weight for Cd and Pb respectively) and International Guidelines. The hazard index (HI) for both metals in the edible portion of studied considering metal levels in the edible portion and the rate of fish consumption by the Mexican population (in adults and children) was less than 1 (HI < 1), values which do not represent a health risk to consumers.

Total mercury concentrations in white and striped Mullet (Mugil curema and M. cephalus) from a coastal lagoon in the SE Gulf of California.

The White and Striped mullets (Mugil curema and M. cephalus) are highly abundant and commercially important estuarine fish in northwest (NW) Mexico. Because of their feeding habits and habitat, they are likely to accumulate mercury (Hg) in their muscle and liver. The objectives of this study were to determine total Hg distribution in the tissues of interest, to correlate Hg levels between tissues and with length and weight of fish, to estimate the percentage weekly intake (PWI) of total Hg and methyl Hg (MeHg) through consumption of both mullet species, and to compare total Hg levels with mullets from other areas. The highest total Hg concentration (1.031 µg g-1 dry weight) was measured in liver of White mullet. In both species, the order of averaged Hg concentrations (M. curema liver 0.272, muscle 0.184; M. cephalus liver 0.211, muscle 0.129 µg g-1 dry weight) were liver>muscle. Correlations of Hg in muscle and liver with total weight of M. curema were significant. In M. cephalus, Hg levels in liver were significantly correlated with total length and weight. The PWI of THg (<4%) and MeHg (<10%) were not elevated for both species. Concentration of Hg in the studied mullets was comparable to levels in similar species from Mexican waters but lower than results in mugilids from other coastal areas.

Bioaccumulation of arsenic and selenium in bycatch fishes Diapterus peruvianus, Pseudupeneus grandisquamis, and Trachinotus kennedyi from shrimp trawling in the continental shelf of Guerrero, México.

With the aim of determining arsenic (As) and selenium (Se) concentrations in bycatch fishes from SW Mexico and comparing elemental concentrations with limits for human consumption set in the national and international legislation, three fish species (Diapterus peruvianus, Pseudupeneus grandisquamis, and Trachinotus kennedyi) were collected from Guerrero state during trawling operations. Additionally, As and Se levels in muscle tissue were compared with similar species from diverse areas. The order of As and Se concentrations was T. kennedyi>P. grandisquamis>D. peruvianus. In Mexico, there is no regulation of As and Se levels in fish. In comparison to the legal limit (0.1 µg g(-1) wet weight) set by legislation in Venezuela, As levels in the edible portion of T. kennedyi (0.632 µg g(-1) wet weight), P. grandisquamis (0.166 µg g(-1) wet weight), and D. peruvianus (0.157 µg g(-1) wet weight) were above this limit. In the case of Se, average concentrations in T. kennedyi (0.323 µg g(-1) wet weight) were above the maximum permissible limit (0.30 µg g(-1) wet weight) set in the Chilean legislation. Se concentrations in Carangoides bajad from Saudi Arabia were comparable to values in T. kennedyi (this study). In relation to As, concentrations varied in magnitude orders; the highest As concentration (range 10.35 to 23.71 µg g(-1) wet weight) corresponded to Mullus barbatus from the Iberian Mediterranean.

Mercury levels in selected bycatch fish species from industrial shrimp-trawl fishery in the SE Gulf of California.

Baseline Hg concentration in bycatch fish from the SE Gulf of California were determined in muscle and liver of 19 species. Levels of Hg in muscle were compared with legal limits of this element in national and international legislation. Considering all fish species, mean concentrations in liver (2.458±1.997 µg g⁻¹) were significantly higher (p<0.05) than in muscle (0.993±0.670 µg g⁻¹). The sequence of averaged Hg concentrations in most ichthyofauna was liver>muscle. Highest level of Hg in muscle (2.556 µg g⁻¹) and liver (7.515 µg g⁻¹) corresponded to Diapterus peruvianus and Ophioscion strabo, respectively. Considering muscle samples, none of the species had levels of Hg above the limit (1.0 µg g⁻¹ wet weight) in the Mexican legislation; with respect to the Japanese (0.4 µg g⁻¹ wet weight) and British (0.3 µg g⁻¹ wet weight) legislations, 26.3% and 31.6% of the species respectively, were above the corresponding limits.