Silver migration from silver-modified activated carbon applied as a water filtration medium in classic cartridges of jug filter systems

Abstract

A comprehensive study was undertaken in order to examine the possible adverse effect of jug filter systems (JFSs) on the quality of filtered water taking into account the released amounts of silver (Ag) into the filtered test water. Nine brands of JFSs (A-I) were investigated according to BS 8427:2004 using a validated ICP/MS method. Essential modification of BS 8427:2004 within the domain of the composite sample preparation was proposed and applied during the tests. The established grand mean concentrations of released Ag from A-H classic cartridges (containing Ag-modified activated carbon and ion exchange resins) and I classic cartridge (containing non-modified activated carbon and ion exchange resin) installed in corresponding JFSs were in the range of 2.6-13.1 µg l⁻¹ and lower than 0.014 µg l⁻¹, respectively. These values were applied for the estimation of the daily intakes of Ag connected with the consumption of water filtered using JFSs (ranging from < 0.0004 to 0.374 µg kg⁻¹ day⁻¹). After taking into account the grand mean concentrations of Ag established during the whole cycle of exploitation for nine JFSs and on the basis of available toxicological data for this element, no long-term risk for human health with respect to appearance of argyria (a condition caused by improper exposure to the Ag or Ag compounds) could be expected (the Hazard Quotient indices estimated as ratios of the daily intakes to the reference dose of Ag were equal or lower than 0.075). Ag-modified activated carbon is not included in the positive list of the authorised substances of the European Commission Regulation (EU) No. 10/2011. Additionally, this material has not been approved by European Food Safety Authority (EFSA). A part of water filtered by JFSs can be directly consumed as drinking water and additionally the remaining water can be applied for the preparation of food products (drinks, soups, etc.). In both cases the quality of water has to fulfil the requirements listed in Directive 98/83/EC (Regulation (EC) No. 178/2002 defines the quality of water intentionally incorporated into the food after the point of compliance as defined in Article 6 of Directive 98/83/EC). However, it should be underlined that point-of-use water treatment units (including JFSs) are not regulated under Directive 98/83/EC and additionally the parametric value for Ag is not included in this document. Therefore, a provisional migration limit for Ag leached from JFSs at the level of 25 µg l⁻¹ was proposed. This value for Ag would limit intake to less than 13% of the human No Observed Adverse Effect Level (NOAEL) (0.39 mg person⁻¹ day⁻¹), using an assumption that each day 2 L of filtered water is consumed containing this metal at the provisional migration limit. All the JFSs tested meet this requirement.

A re-assessment of the safety of silver in household water treatment: rapid systematic review of mammalian in vivo genotoxicity studies

“…With the current evidence it is not yet possible to determine a safe limit for the oral intake of AgNP or colloidal Ag. Before colloidal Ag or AgNP are used in filter matrices for drinking water treatment, consideration needs to be given to how much silver is likely to be released from the matrix during the life of the filter (eg work by Garboś and colleagues) [32, 33]. There is an urgent need for more research on this topic and particularly on whether people using colloidal Ag as a primary drinking water treatment, working with AgNP in filter manufacture in low income countries or using such impregnated filters have evidence of DNA damage.…”

Atomic spectrometry update: Review of advances in the analysis of clinical and biological materials, foods and beverages

“…Concerns that this could potentially trigger argyria prompted a study of nine jug ltration systems available in Poland. 152 Determined by ICP-MS, the released Ag content ranged between 2.6 and 13.1 mg L À1 from lters containing modied-activated charcoal while one lter which used non-modied activated charcoal only released an Ag concentration <0.014 mg L À1 . Based on a daily consumption of 2 L, the authors determined a maximum exposure rate of 0.374 mg kg À1 day À1 , a hazard quotient <0.075, and concluded jug lters posed no long-term threat to health.…”

Behavior of Pseudomonas aeruginosa and Enterobacter aerogenes in Water from Filter Jugs

“…Several studies on the release of silver from pitcher filter cartridges have recently been performed [18,19], though specific controls and studies related to microbiological populations in filtered water are limited. No alerts involving water jugs have been reported via the Rapid Alert System for Food and Feed (RASFF) [20] and the Rapid Alert System for dangerous nonfood products (RAPEX) [21].…”