Are the levels of mercury present in fishery products adequate to ensure low risk for populations that consume a lot of fish? A new study led by scientists from the Department of Life Sciences (DCV) of the Faculty of Science and Technology of the University of Coimbra (FCTUC) reveals that the highest mercury values were determined in carnivorous species (which feed on smaller animals), such as hake, which may have adverse effects on human health due to the concentration of mercury.
Taking into account the recommended daily portions on the Food Wheel that define a complete and balanced diet, the study “Are mercury levels in appropriate fishery products to ensure low risk to high fish-consumption populations?” determined the weekly frequency with which the population residing in Portugal can consume cod, hake, and cooked octopus, as well as grilled horse mackerel and sardines, in order to prevent adverse health effects, since some marine species may contain high concentrations of methylmercury.
Methylmercury, explains Elsa Teresa Rodrigues, study coordinator and researcher at the DCV and Center for Functional Ecology (CFE) is «a chemical form of mercury with the potential to bioaccumulate in biological tissues and with high neurotoxicity, and it was found in this study that hake (over 1 kg) cooked and consumed more than once a week, and horse mackerel (35-40 cm) grilled and consumed more than five times a week, exceeds the value of methylmercury accepted as safe and established by European Agency for Food Safety. Cooked cod and octopus, as well as grilled sardines, when purchased and cooked under the tested conditions, can be consumed without restrictions », she reveals.
To arrive at these results, the FCTUC team purchased fresh products on the market, with the exception of cod from Norway (salted and dried), and simulated traditional cooking methods in the laboratory. «The detection and quantification of total mercury and methylmercury present in the raw and cooked samples were carried out by atomic absorption spectrometry with direct combustion of the sample», describes Elsa Teresa Rodrigues.
According to the CVD scientists, “it was found that the culinary treatments tested always resulted in an increase in the concentration of mercury; and that in all situations tested (raw and cooked samples, total mercury and methylmercury), the highest levels were found in hake and horse mackerel».
«In addition to the scientific knowledge produced, with this study we contribute to a safe and healthy diet for the population residing in Portugal, since we respond to one of the societal challenges associated with the food sector: helping consumers make informed choices», concludes the team.
This investigation, funded by the Foundation for Science and Technology (FCT), in addition to DCV, also includes scientists from the University of Aveiro.
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