efsa-opinion-chromium-food-drinking-water

4.2.2.2. Data collection on drinking water
Chromium in food and drinking water
In the FoodEx classification system (EFSA, 2011a) the different types of water (bottled water, tap
water, water ice and well water) are grouped under the generic name ‘Drinking water’. Therefore, the
generic term ‘Drinking water’ as used in this opinion includes both water intended for human
consumption (Council Directive 98/83/EC) and natural mineral waters (Commission Directive
2003/40/EC). Bottled water as used in this opinion includes natural mineral water, but also spring
water and other bottled drinking water, products that must comply with Council Directive 98/83/EC.
Before applying any data quality criteria 52 735 analytical results on drinking water were present in
the database. Since 88 samples reported data for both total chromium and Cr(VI), results for
52 647 different drinking water samples were available. The same procedure followed for the food
samples was applied to water, eliminating the samples reported as ‘suspect samples’ and those without
neither LOD nor LOQ. In this step, a total of 5 211 were excluded of the dataset (4 929 without
neither LOD nor LOQ and 282 as suspect samples).
Legislation establishes performance characteristics for the methods used to analyse the presence of
chromium in water intended for human consumption (Council Directive 98/83/EC) and in natural
mineral waters (Commission Directive 2003/40/EC). Based on the concentration limits described in
both pieces of legislation (50 µg/L) a maximum LOD of 5 g/L is established for the analytical
methods in use. As all the samples reported LOQs but only 40 % LODs, it was decided that the cut-off
value should be applied to the LOQ. A cut-off value of 10 g/L for total chromium was selected
taking into account legislation and the available literature on chromium analysis in water. A total of
1292 samples were eliminated (136 quantified). No cut-off value was applied to the analytical data on
Cr(VI).
After applying the selected cut-off of 10 g/L a total of 46 234 analytical results (46 146 on total
chromium and 88 on Cr(VI)) on drinking water were included in the final dataset. Information on the
country of sampling and the sampling year is provided in Figures 7 and 8, respectively. As for food,
most of the samples were collected in Germany ( 82 %) followed by Cyprus ( 11 %). Water
samples adequately representing the years between 2000 and 2012 were collected (a minimum of
1 000 analytical data/year).
For all the different types of drinking water samples reported, i.e., bottled water, tap water, water ice,
and well water, it was difficult to predict the amount of Cr(VI) present. The CONTAM Panel decided
to consider all chromium present in drinking water as Cr(VI) (worst case scenario) based on two facts.
First, the samples where both Cr(VI) and total chromium were quantified (71 out of 88 samples)
showed an average ratio Cr(VI)/total chromium of 0.97. In addition, as previously mentioned in this
scientific opinion, tap water is usually treated with different oxidizing agents to make it potable, and
this would promote the presence of Cr(VI) instead of Cr(III).
EFSA Journal 2014;12(3):3595 40