Résumé
Following a request from the European Commission (EC), the Panel on food additives, flavourings, processing aids and materials in contact with food (AFC) was asked to issue a scientific opinion on the safety in use of the treatments for the removal of manganese, iron and arsenic from Natural Mineral Waters (NMWs) by oxyhydroxide media. The opinion is based on reports of the European Commission, Health and Consumer Protection Directorate-General (DG SANCO) and of EU Member States (for technological and risk assessment issues) and on scientific literature (for technological issues).
Directive 2003/40/EC sets limits for arsenic (0.01 mg/L) and manganese (0.5 mg/L) in NMWs. According to Directive 80/77/EEC, in order to reduce the level of undesirable constituents, NMWs may be treated by authorised processes in so far as the treatment does not alter the composition of the essential constituents of the water.
Reports of DG SANCO compiled data demonstrating that treatments of NMWs with iron and manganese oxyhydroxides based media can achieve a reduction in the concentrations of arsenic, manganese and iron to desired levels. Arsenic was not detectable in water treated with these media (< 1 mu g/L). Other undesirable constituents (like vanadium and uranium) may also be reduced. The mechanism by which these species are removed is adsorption, a physical process with high selectivity. A wide variety of oxyhydroxides are used in the EU; they differby country, by the composition of the water and by the process conditions. To ensure that these treatments do not endanger public health through a chemical contamination of the treated NMW, it is recommended in first instance that the oxyhydroxide media comply with the standards applicable for their use in drinking water treatment. These standards cover both the composition of the media and the reagents used for their initialisation, regeneration and disinfection.
The EFSA has received data enabling the evaluation of three categories of media:
iron and/or manganese coated silica sand, zeolite and activated alumina (obtained by self coating when flowing the NMW on sand, without addition of any chemical),
natural manganese ores and
synthetic iron based oxyhydroxides.
In this opinion, the following critical steps of the processes have been addressed:
Initialisation of the media by washing with bases and acids to remove leachable impurities.
Regeneration of the media by an appropriate chemical treatment (rinsing, elution or oxidative regeneration) to restore their adsorption capacity.
Disinfection of the media by a dedicated disinfection treatment to remove possibly formed biofilms.
Testing and controls should be conducted to ensure that the media do not release impurities in concentrations exceeding the limits set in Directive 2003/40/EC or, in the absence of limits in this Directive, the restrictions for water intended for human consumption set in Directive 98/83/EC or in applicable national legislation.
Monitoring of the possible presence of by-products, especially after disinfection of the media and after oxidative regeneration treatments which do not involve washings with base and acid. Chlorine-based disinfection treatments should not be used.
Control of the return to normal composition of the water after initialisation, regeneration, disinfection and rinsing operations with adequate methods.
The processes should be subject to Good Manufacturing Practice and Hazard Analysis Critical Control Points principles covering the specific legal requirements for NMWs and addressing the risks identified in this opinion.
The Panel concluded that the removal of manganese, iron and arsenic from NMWs by the oxyhydroxide media as mentioned above can be safely applied provided the critical steps are implemented and monitored appropriately.