A study which indicates the competence of global laboratories to measure heavy metals in seafood should enhance consumer confidence but there are concerns over arsenic estimates, according to a report from the EC’s Joint Research Centre.
“The outcome of the exercise was generally positive, with 80 to 96 per cent of laboratories obtaining satisfactory scores, depending on the heavy metal considered,” reported the JRC, a Directorate-General of the European Commission.
However, the centre notes: “Participants tended to underestimate the content of total arsenic, and to a lesser extent total cadmium.”
And, it said that, contrary to a previous exercise (IMEP-107 on total and inorganic arsenic in rice), the values reported for inorganic arsenic showed a large spread.
“Interestingly, this indicates that the matrix (in this case, seafood), has a major influence on the analytical determination of inorganic arsenic. This is a crucial consideration for legislators, because specifying single maximum level of arsenic in food would appear to be unfeasible,” concluded the report.
Ines Baer, one of the authors of the study, told FoodProductionDaily.com today that another trial is set for early 2011 to determine interlaboratory measurement competence of inorganic arsenic in cereals and other plant based food matrices.
The JRC, which conducts benchmarking interlaboratory comparisons in support of EU policies, said its trial involved the participation of 57 laboratories from 29 countries that voluntarily put their competence in measuring arsenic, cadmium, lead and mercury in seafood to the test.
“Each laboratory received a sample without knowing the levels of heavy metals present, and was asked to measure and report the values back to the JRC,” reported the researchers.
The laboratories, continued the JRC, were asked to report both the measured value of each heavy metal in question in the sample and the uncertainties associated with those measurements. The results were scored according to international standards
Heavy metals, along with pathogenic micro-organisms, allergens, and mycotoxins were among the risks most commonly reported through the European Union’s food safety alert system last year, according to a European Commission report in September.
The JRC maintains that excessive intake of heavy metals may lead to a decline in mental, cognitive and physical health. A particular concern is potential developmental defects in children exposed in utero, it adds.
From a toxicological point of view, the chemical form in which the metal is ingested plays a significant role. “For example, methylmercury is much more toxic than inorganic mercury compounds, whilst inorganic arsenic is more toxic than the organic species of arsenic,” said the researchers.
In Europe, maximum levels for lead, cadmium and total mercury in food are laid down in legislation, varying from 0.5 to 1.0 mg per kg for different seafood.
The JRC said that no maximum level exists for the methylmercury form of mercury, as its measurement requires specific analytical equipment not routinely present in testing laboratories. “However, methylmercury is the main source of human intake of mercury in fish and fishery products, and is important due to its high toxicity compared to inorganic mercury,” explained the researchers.
No maximum levels for arsenic have been laid down in European legislation either, due to a lack of information about reliable analytical methods for determining inorganic arsenic in different food commodities, and measurement values of inorganic arsenic are generally believed to be method-dependent.
“The interlaboratory comparison was, therefore, extended to include methylmercury and inorganic arsenic, in order to investigate the issues that laboratories encounter in measuring these substances,” added the JRC.