Mercury in Canned Tuna in Spain. Is Light Tuna Really Light?

Montserrat González-Estecha, María José Martínez-García, Manuel Fuentes-Ferrer, Andrés Bodas-Pinedo, Alfonso Calle-Pascual, José María Ordóñez-Iriarte, Cristina Fernández-Pérez, Nieves Martell-Claros, Miguel Ángel Rubio-Herrera, Emilia Gómez-Hoyos, José Jesús Guillén-Pérez

Consejería de Sanidad y Consumo, Madrid, Spain.
Department of Endocrinology, Instituto de Investigación Sanitaria, Hospital Clínico San Carlos, Madrid, Spain.
Department of Pediatrics, Instituto de Investigación Sanitaria, Hospital Clínico San Carlos, Madrid, Spain.
Hypertension Unit, Instituto de Investi- gación Sanitaria, Hospital Clínico San Carlos, Madrid, Spain.
Publich Health Department, Cartagena, Spain; Universidad de Mur- cia, Murcia, Spain..
Trace Element Unit and Laboratory Medicine Department, Instituto de Investigación Sanitaria, Hospital Clínico San Carlos, Madrid, Spain.
Universidad Camilo Jose Cela, Madrid, Spain;Department of Epidemiology, Instituto de Investigación Sanitaria, Hospital Clínico San Carlos, Madrid, Spain.
Universidad Politécnica, Cartagena, Spain.

DOI: 10.4236/fns.2013.47A007                

Abstract

In Spain, certain population-based studies have shown high blood mercury (Hg) levels due to the high consumption of fish. Some studies have stated that one of the most consumed fish in Spain is canned tuna. Different Spanish organisms consider that it is safe to consume canned tuna as it supposedly has a low mercury content, particularly in so-called light tuna. However, in Spain light tuna is mainly yellowfin and bigeye tuna, while in other countries it is mainly skipjack tuna. This study analyzed 36 cans of the most popular brands in Spain and examined the influence of the type of tuna, packaging medium (olive oil, sunflower seed oil, water or marinade), different brands, prices and expiration dates. Mercury concentrations (mg/kg) were measured by atomic absorption spectrometry and thermal decomposition amalgamation. The medians observed were (mg/kg): light tuna: 0.314; IQR: 0.205 - 0.594, white tuna: 0.338; IQR: 0.276 - 0.558, skipjack: 0.311; IQR: 0.299 - 0.322, frigate tuna: 0.219; IQR 0.182 - 0.257 and mackerel: 0.042; IQR 0.029 - 0.074. We found statistically significant differences between white tuna, light tuna and mackerel (p = 0.004); light tuna and mackerel (p = 0.002) and white tuna and mackerel (p = 0.006). However, we found no differences between white tuna and light tuna, or among packaging medium, brands, prices or expiration dates. The limit of 0.500 mg/kg of mercury in canned tuna was exceeded by the following percentages of the cans: 33.3% of light tuna, 16.7% of white tuna, and 0% of Skipjack, frigate tuna and mackerel. The mercury content of the cans of Spanish light tuna that were analyzed was variable and high. The results of this study indicate that stricter regulation of Hg in canned tuna is necessary. Until then, it is safer to recommend that vulnerable populations such as children and pregnant women consume canned mackerel, which has a markedly lower mercury content.

Keywords

Mercury; Canned Tuna; Spain

Conflicts of Interest

The authors declare no conflicts of interest.

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