Laboratories show they can accurately measure heavy metals

A new report studying the abilities of laboratories worldwide to measure heavy metals - arsenic, cadmium, lead, mercury, methylmercury and inorganic arsenic - in seafood has been published by the Joint Research Centre (JRC). Of the 57 laboratories who reported back on their values, 80-96 per cent showed satisfactory scores depending on the heavy metal tested. 

A total of 57 laboratories from 29 countries from across the globe volunteered to test their measuring competence test. The JRC sent each laboratory a sample of heavy metals - while unaware of the levels present - and the labs had to measure and report the values back to the JRC.

Seafood consumers in the European Union (EU) may find comfort in the results, as levels of lead, cadmium and total mercury are regulated by law in the Union and most laboratories who participated in the interlaboratory comparison demonstrated that they could accurately measure them.

Moreover, the project underlined issues including the apparent dependency of the measurements of inorganic arsenic on the type of food tested.

It has been shown that excessive consumption of foods containing heavy metals could cause a decline in mental, cognitive and physical health levels, and this is especially troubling in regards to potential developmental defects in children exposed in utero, JRC said. 

From a toxicological perspective, the chemical form in which the metal is consumed is important; for instance, while methylmercury is much more toxic than inorganic mercury compounds, inorganic arsenic is more toxic than its organic species.

In opposition to a previous exercise (IMEP-107 on total and inorganic arsenic in rice), the values reported for inorganic arsenic appeared widespread, indicating that seafood has a strong influence on the analytical determination of inorganic arsenic. This is key knowledge for legislators, as specifying single maximum level of arsenic in food thus seems unfeasible.

In the EU, maximum legal levels for lead, cadmium and total mercury in food vary from 0.5 to 1.0 mg per kg for different seafood, but no maximum level exists for the methylmercury form of mercury because its measurement necessitates specific analytical equipment usually unavailable in testing laboratories. At the same time, most human intake of mercury comes from methylmercury in fish and fishery products and has a high toxicity compared to inorganic mercury.

As well, no maximum levels for arsenic have been set in European legislation because of insufficient information about reliable analytical methods for determining inorganic arsenic in different foods, and its measurement values are normally thought method-dependent.

The study was organised in support of the European Co-operation for Accreditation (EA), the Asia Pacific Laboratory Accreditation Cooperation (APLAC) and the national reference laboratories associated to the EU Reference Laboratory for Heavy Metals in Feed and Food.