Need of guidelines for limits on trace elements in canned vegetables
The JRC, in its role as European Union Reference Laboratory on Heavy Metals (EURL-HM) organised a proficiency test (PT) for the determination of some heavy metals (trace elements) in canned peas. This study revealed that a harmonised sample preparation protocol needs to be used to avoid conflicting decisions about compliance with legislation.
Contamination with toxic elements is a global environmental and food safety concern. Even though metal cans are mostly coated with resins to protect food coming in to the contact with metal, metal cans can be a source of contamination and the occurrence of toxic trace elements in canned food is an issue of concern. Therefore, the European Union has a strict legislative framework setting maximum levels for certain heavy metals in food products. It is the role of the EURL-HM to organise proficiency tests for the National Reference Laboratories (NRL) to not understand only the measurement capacity of NRLs but also to get an insight into the analytical challenges, especially regarding different food matrices.
The recent proficiency test organised by the JRC - hosting the EURL-HM - focused on the determination of total arsenic, inorganic arsenic, cadmium, lead, mercury and tin in canned peas. In total, 127 laboratories (including NRLs) from 36 countries participated in the study. The study revealed that most laboratories lacked guidance documents to be used for the analysis of canned food. Moreover, two different sample preparation approaches were used by laboratories even coming from the same country. The majority of the participating laboratories indicated that their sample preparation strategy is based on common sense, considering what is intended for consumption and what is not, i.e. including the brine or not for the analysis. From the participating laboratories 54 % analysed the drained product and 46 % the solid/liquid composite, leading to different decisions about whether the canned peas should or not be allowed in the European market.
It is therefore of utmost importance to have clear sample preparation guidelines to arrive to a harmonised assessment whether a sample is compliant or not.