Research concludes that the consumption of hake can have adverse effects on health due to high levels of mercury
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 daily portions recommended in the Food Wheel that define a complete and balanced diet, the study “Are mercury levels in fishery products appropriate 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, to prevent adverse health effects, as some marine species may contain high concentrations of methylmercury.
Methylmercury, explains Elsa Teresa Rodrigues, coordinator of the study and researcher at DCV and the Center for Functional Ecology (CFE), is «a chemical form of mercury with potential for bioaccumulation in biological tissues and with high neurotoxicity, and in this study it was found that hake (over 1kg) 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 methylmercury value accepted as safe and established by European Food Safety Agency. Cooked cod and octopus, as well as grilled sardines, when purchased and cooked under tested conditions, can be consumed without restrictions", she reveals.
To achieve these results, the FCTUC team purchased fresh products from the market, except for Norwegian cod (salted and dried), and simulated traditional culinary methods in the laboratory. «The detection and quantification of total mercury and methylmercury present in raw and cooked samples was carried out using atomic absorption spectrometry with direct combustion of the sample», describes Elsa Teresa Rodrigues.
According to DCV scientists, “it was found that the culinary treatments tested always increased mercury concentration; and that in all situations tested (raw and cooked samples, total mercury and methylmercury), the highest levels were determined 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, as we respond to one of the societal challenges associated with the food sector: helping consumers make informed choices», concludes the team.
This research, funded by the Foundation for Science and Technology (FCT), also includes scientists from the University of Aveiro.