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

doi:10.1016/j.jtemb.2020.126641

Journal of Trace Elements in Medicine and Biology

Volume 62, December 2020, 126641

https://doi.org/10.1016/j.jtemb.2020.126641 Get rights and content

Highlights

•
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.

Abstract

Background

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.

Methods

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).

Results

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.

Conclusion

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.

Introduction

Methylmercury is an important food toxicant [[1], [2], [3], [4]]. In humans it deposits mainly in the brain [[5], [6], [7], [8]] and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) established provisional tolerable weekly intake (PTWI) for methylmercury of 1.6 μg/kg bw based on developmental neurotoxicity [9].

Fish is the main route of human chronic exposure to methylmercury [1,7,10,11]. This contaminant is biomagnified in the aquatic trophic chain, from plankton to the largest predatory fish [3,12,13]. It also bioaccumulates more in some types of fish compared to the others. In this way, the beneficial effects and risks of fish consumption can vary according to the fish species, its size and origin [3,[14], [15], [16], [17]], as well as on the amount and the fish preparation methods for commercialization and consumption [[18], [19], [20], [21]].

In Brazil, studies on mercury exposure are mainly focused in the Northern region [13,14,17,[22], [23], [24]] and mostly associated with mining areas, although mercury has been found in fish from other regions [12,14,16,[25], [26], [27], [28]]. So the possible risk of methylmercury in food to the health of most Brazilians is still unclear. FAO/WHO [29] recommended countries to develop and evaluate risk management and communication strategies that could minimize risks and maximize benefits from fish eating. To do so, reliable information on exposure to methylmercury is required.

The analysis of methylmercury is complex and it is still not widely available, especially in developing countries. Thus, a simpler method for total mercury analysis has been used to predict methylmercury contents in fish [7,14,17,29,30]. Approximately 80–100% of total mercury in fish muscle is methylmercury [2,3,20,29,[31], [32], [33]] and the estimation of dietary exposure to methylmercury can be calculated assuming a conservative approach considering that all total mercury found in fish is methylmercury [7] or some value around 90% [1,2]. Thus, the objective of this work was to quantify total mercury levels in different fish commercialized in Brazil and to access the risk associated with methylmercury from estimated Brazilian dietary exposure.

Section snippets

Chemicals

A 1000 mg/L ±2 mg/L standard solution of inorganic mercury (99.8%) dissolved in 12% w/v HNO₃ was obtained from Sigma (Sigma-Aldrich Co., St. Louis, MO, USA). Nitric acid 65% w/w EMSURE® ISO was purchased from Merck (Merck KGaA, Darmstadt, Germany). The solutions were prepared using high-purity water with a resistivity of 18.2 MΩ.cm, obtained from a Milli-Q Plus water purification system (Millipore, Bedford, MA, USA).

Samples

Fish samples were collected from wild and farmed fisheries, from sea (n = 52)

Performance of the method for total mercury analysis

The calibration curve of mercury standards in 1% w/v HNO₃ showed linearity in the range of 1.0–8.5 ng Hg (R² = 0.9962). The calibration curve in the blank fish matrix also showed linearity in the same range (R² = 0.9948). The existence of matrix effect was evaluated by comparison of the inclinations and intercepts of both calibration curves. There was no significant difference between the intercepts; however, the inclinations were significantly different (p < 0.05, t test for homoscedastic

Conclusions

Overall, 113 samples of fish from different regions of Brazil were analyzed for total mercury. All samples showed total mercury levels within the limits established by the Brazilian regulations (0.5 mg/kg for non-predatory fish and 1.0 mg/kg for predatory fish). Differences on mercury levels were observed, with higher levels for carnivorous fish (0.23 mg/kg) compared to non-strictly carnivorous fish (0.06 mg/kg). Farmed fishes showed significantly lower levels compared to wild fish, indicating

CRediT authorship contribution statement

Flávia Beatriz Custódio: Methodology, Investigation, Writing - original draft, Supervision. Arthur Magno G.F. Andrade: Conceptualization, Methodology, Investigation, Data curation, Formal analysis, Writing - original draft. Letícia R. Guidi: Methodology, Validation, Writing - review & editing. Carlos A.G. Leal: Methodology, Investigation, Writing - review & editing. Maria Beatriz A. Gloria: Conceptualization, Methodology, Investigation, Writing - review & editing, Funding acquisition,

Declaration of Competing Interest

The authors declare that they have no known conflicts of interest or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This research was supported by Fundação de Amparo a Pesquisa do Estado de Minas Gerais – FAPEMIG (Belo Horizonte, MG, Brazil), Coordenação de Pessoal de Nível Superior – CAPES, and Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq (Brasília, DF, Brazil).

References (49)

L. Cao et al.
Biomagnification of methylmercury in a marine food web in Laizhou Bay (North China) and associated potential risks to public health
Mar. Pollut. Bull.
(2020)
S. Ekino et al.
Minamata disease revisited: an update on the acute and chronic manifestations of methyl mercury poisoning
J. Neurol. Sci.
(2007)
L.S. Azevedo et al.
Organotropism of methylmercury in fish of the southeastern of Brazil
Chemosphere
(2017)
J.M. Soares et al.
Mercury in fish from the Madeira River and health risk to Amazonian and riverine populations
Food Res. Int.
(2018)
F.N. Costa et al.
Preliminary results of mercury levels in raw and cooked seafood and their public health impact
Food Chem.
(2016)
C.L. Mieiro et al.
Fish and mercury: influence of fish fillet culinary practices on human risk
Food Control
(2016)
C. Afonso et al.
Bioaccessibility in risk-benefit analysis of raw and cooked seabream consumption
J. Food Compos. Anal.
(2018)
G.P.F. Arrifano et al.
Large-scale projects in the amazon and human exposure to mercury: the case-study of the Tucuruí Dam
Ecotoxicol. Environ. Saf.
(2018)
A.S. Lino et al.
Mercury and selenium in fishes from the Tapajós River in the Brazilian Amazon: an evaluation of human exposure
J. Trace Elem. Med. Biol.
(2018)
K. Faial et al.
Mercury levels assessment in hair of riverside inhabitants of the Tapajós River, Pará State, Amazon, Brazil: fish consumption as a possible route of exposure
J. Trace Elem. Med. Biol.
(2015)

F. Fuentes-Gandara et al.

Assessment of human health risk associated with methylmercury in the imported fish marketed in the Caribbean

Environ. Res.

(2018)

C. Feitosa-Santana et al.

Color vision impairment with low-level methylmercury exposure of an Amazonian population – brazil

NeuroToxicol.

(2018)

IOMC

Inter-Organisation Programme for the Sound Management of Chemicals)

Guidance for Identifying Populations at Risk From Mercury Exposure. UNEP/WHO, Geneva

(2008)

N. Watanabe et al.

Distribution and chemical form of mercury in commercial fish tissues

J. Toxicol. Sci.

(2012)

D. Mozaffarian et al.

Fish intake, contaminants, and human health evaluating the risks and the benefits

J. Am. Med. Assoc.

(2006)

D. Mergler et al.

Methylmercury exposure and health effects in humans: a worldwide concern

Ambio

(2007)

EFSA (European Food Safety Authority)

Panel on Contaminants in the Food Chain (CONTAM): scientific opinion on the risk for public health related to the presence of mercury and methylmercury in food

EFSA J.

(2012)

R.C. Marques et al.

Role of methylmercury exposure (from fish consumption) on growth and neurodevelopment of children under 5 years of age living in a transitioning (tin-mining) area of the Western Amazon, Brazil

Arch. Environ. Contam. Toxicol.

(2012)

JECFA (Joint FAO/WHO Expert Committee on Food Additives)

Safety evaluation of certain contaminants in food: methylmercury

WHO Food Addit. Ser.

(2007)

J.M. Gendzier

Risk and regulation: methylmercury exposure and fish consumption. Vanderbilt Undergrad

Res. J.

(2010)

JECFA (Joint FAO/WHO Expert Committee on Food Additives)

Safety evaluation of certain contaminants in food: mercury (addendum)

FAO JECFA Monogr.

(2011)

A.R.M. Rocha et al.

Isotopic profile and mercury concentration in fish of the lower portion of the rio Paraíba do Sul watershed, southeastern Brazil

Neotrop. Ichthyol.

(2015)

S.F. Silva et al.

Mercury in fish marketed in the Amazon triple frontier and health risk assessment

Chemosphere

(2020)

Z. Castilhos et al.

Human exposure and risk assessment associated with mercury contamination in artisanal gold mining areas in the Brazilian Amazon

Environ. Sci. Pollut. Res.

(2015)

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¹: Present address: Departamento de Ciências do Consumo, Universidade Federal Rural de Pernambuco (UFRPE), 52171-900, Recife, Pernambuco, Brasil.

View full text

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

Highlights

Abstract

Background

Methods

Results

Conclusion

Introduction

Section snippets

Chemicals

Samples

Performance of the method for total mercury analysis

Conclusions

CRediT authorship contribution statement

Declaration of Competing Interest

Acknowledgements

Mar. Pollut. Bull.

J. Neurol. Sci.

Chemosphere

Food Res. Int.

Food Chem.

Food Control

J. Food Compos. Anal.

Ecotoxicol. Environ. Saf.

J. Trace Elem. Med. Biol.

J. Trace Elem. Med. Biol.

Environ. Res.

NeuroToxicol.

Inter-Organisation Programme for the Sound Management of Chemicals)

Guidance for Identifying Populations at Risk From Mercury Exposure. UNEP/WHO, Geneva

Distribution and chemical form of mercury in commercial fish tissues

J. Toxicol. Sci.

Fish intake, contaminants, and human health evaluating the risks and the benefits

J. Am. Med. Assoc.

Methylmercury exposure and health effects in humans: a worldwide concern

Ambio

Panel on Contaminants in the Food Chain (CONTAM): scientific opinion on the risk for public health related to the presence of mercury and methylmercury in food

EFSA J.

Role of methylmercury exposure (from fish consumption) on growth and neurodevelopment of children under 5 years of age living in a transitioning (tin-mining) area of the Western Amazon, Brazil

Arch. Environ. Contam. Toxicol.

Safety evaluation of certain contaminants in food: methylmercury

WHO Food Addit. Ser.

Risk and regulation: methylmercury exposure and fish consumption. Vanderbilt Undergrad

Res. J.

Safety evaluation of certain contaminants in food: mercury (addendum)

FAO JECFA Monogr.

Isotopic profile and mercury concentration in fish of the lower portion of the rio Paraíba do Sul watershed, southeastern Brazil

Neotrop. Ichthyol.

Mercury in fish marketed in the Amazon triple frontier and health risk assessment

Chemosphere

Human exposure and risk assessment associated with mercury contamination in artisanal gold mining areas in the Brazilian Amazon

Environ. Sci. Pollut. Res.