Total mercury in commercial fishes and estimation of Brazilian dietary exposure to methylmercury

• Published in: Journal of trace elements in medicine and biology Vol. 62; p. 126641
• Main Authors: Custódio, Flávia Beatriz, Andrade, Arthur Magno G.F., Guidi, Letícia R., Leal, Carlos A.G., Gloria, Maria Beatriz A.
• Format: Journal Article
• Language: English
• Published: Elsevier GmbH 01.12.2020
• Subjects: behavior; Farmed fish; Feeding; Food safety; Heavy metal; Risk assessment; Farmed fish; Food safety; behavior; Risk assessment; Heavy metal; Feeding
• ISSN: 0946-672X; 1878-3252
• DOI: 10.1016/j.jtemb.2020.126641

•Total mercury occurrence was investigated in 18 different fish species.•Farmed fish showed low levels of total mercury.•Estimated methylmercury intake was higher in rural population.•High fish consumers are in risk by dietary methylmercury exposure.•Legislation of mercury in fish is not enough protective for some populations. Mercury, in particular its most toxic form methylmercury, poses a risk to public health. Dietary methylmercury exposure is mainly by fish, and it can vary with fish contamination and by dietary habits of the population. This study aimed to quantify total mercury levels in different fish from Brazil and to estimate Brazilian exposure to methylmercury by fish consumption. Total mercury occurrence was investigated in 18 different fish species by atomic absorption spectrometry with thermal decomposition and gold amalgamation. Dietary exposure to methylmercury was estimated by a deterministic method for different groups considering consumption by sex, different Brazilian geographical regions and habitat (rural or urban). Carnivorous fish showed higher levels of mercury (0.01 to 0.93 mg/kg) compared to non-strictly carnivorous fish (<0.01 to 0.30 mg/kg). Farmed fishes showed significantly lower levels compared to wild fish. Mean Brazilian fish consumption achieves FAO/WHO health recommendation of about two portions of fish per week. However, there is a large difference between fish consumption at urban and rural homes and among Brazilian geographic regions. These differences in consumption impacted estimated methylmercury intake that was higher in the Northern (1.85 μg/kg bw week) and in the Northeastern (0.72 μg/kg bw week) regions and also by rural population (1.08 μg/kg bw week). These values were compared with the toxicological reference dose for neurotoxicity of 1.6 μg/kg bw week. Even though total levels of mercury in fish were lower than Brazilian and international legislations, in the Northern Brazilian region methylmercury intake overpassed the toxicological reference dose for neurotoxicity and in rural areas it achieved 68% of this reference dose.