efsa-opinion-chromium-food-drinking-water
efsa-opinion-chromium-food-drinking-water
efsa-opinion-chromium-food-drinking-water
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Chromium in <strong>food</strong> and <strong>drinking</strong> <strong>water</strong><br />
ASSESSMENT<br />
1. Introduction<br />
Chromium (Cr) was discovered in the second half of the 18th century: its elemental state and<br />
compounds have been the subject of extensive research, also due to their diverse industrial<br />
applications. It occurs in a variety of valence states with trivalent (Cr(III)) and hexavalent (Cr(VI))<br />
being the most stable and biologically relevant oxidation states. For the general population, <strong>food</strong> is the<br />
major source of exposure to <strong>chromium</strong> (> 90 % of the total intake). Drinking <strong>water</strong> may also be a<br />
substantial source of exposure if <strong>chromium</strong> levels are exceptionally high. Cr(III) is a natural dietary<br />
constituent present in a variety of <strong>food</strong>s and also in dietary supplements. Conversely, Cr(VI) seems to<br />
be absent in <strong>food</strong> and its presence in <strong>drinking</strong> <strong>water</strong> is usually a consequence of anthropogenic<br />
activity. Over the last years there have been several reports of naturally occurring Cr(VI) in<br />
ground<strong>water</strong>. Although in most cases the Cr(VI) concentrations found appear to be in the order of a<br />
few µg/L or some tens of µg/L, values of a few hundreds of µg/L are not unusual.<br />
Chromium absorption after dietary exposure in humans is relatively low (< 10 % of the ingested dose)<br />
and is affected by the valence state and the nature of its ligands. Cr(VI) is reduced in the stomach to<br />
Cr(III), which lowers the absorbed dose from ingested Cr(VI). The interconversion of the two species<br />
is of relevance for risk assessment since, in general, Cr(VI) compounds are more toxic than Cr(III)<br />
compounds. This is mostly due to the more effective cellular uptake of Cr(VI) as compared to Cr(III).<br />
Cr(III) presents a low oral toxicity due to poor bioavailability. Oral exposure to Cr(VI) compounds is<br />
associated with gastrointestinal system cancers in experimental animals. In humans, Cr(VI) is a known<br />
carcinogen by the inhalation route of exposure and Cr(VI) compounds are classified by the<br />
International Agency for Research on Cancer (IARC) as carcinogenic to humans (Group 1).<br />
There are no maximum levels (MLs) set for <strong>chromium</strong> in <strong>food</strong>. A parametric value of 50 μg Cr/L for<br />
total <strong>chromium</strong> in <strong>water</strong> intended for human consumption and a Maximum Limit of 50 μg Cr/L for<br />
total <strong>chromium</strong> in natural mineral <strong>water</strong>s are laid down in Council Directive 98/83/EC and in<br />
Commission Directive 2003/40/EC, respectively.<br />
In March 2012, the European Food Safety Authority (EFSA) received a mandate from the Hellenic<br />
Food Authority (EFET) for a scientific <strong>opinion</strong> on estimation of the risk to human health from the<br />
presence total Cr in <strong>food</strong> and Cr(VI) in bottled <strong>water</strong>. This scientific <strong>opinion</strong> addresses the risks for<br />
public health related to the presence of total Cr in <strong>food</strong> and Cr(VI) in <strong>water</strong> intended for human<br />
consumption and natural mineral <strong>water</strong>s.<br />
1.1. Chemistry and physico-chemical properties<br />
In this Section, a summary of the current knowledge on a number of physico-chemical, environmentrelated<br />
properties of <strong>chromium</strong> is given. Due to the very large number of scientific publications,<br />
technical reports and reviews, and educational and press releases available on these topics, no<br />
references are provided in the text unless specifically required. For additional detailed information, a<br />
number of general scientific references are available (e.g. Papp and Lipin, 2001; WHO, 2003;<br />
OEHHA, 2011; Saha et al., 2011; Zhitkovich, 2011; ATSDR, 2012; McNeill et al., 2012a, b).<br />
1.1.1. General aspects<br />
Chromium (Cr; CAS registry No. 7440-47-3) is widely distributed in the earth’s crust, almost always<br />
in the trivalent chromic state (Cr 3+ or Cr(III); CAS registry 16065-83-1); its concentration is in the<br />
order of few tens of mg/kg in most soils. The metal is produced in large quantities for industrial<br />
purposes, its principal ore being ferrochromite (FeCr 2 O 4 or FeOCr 2 O 3 , in short chromite), in which the<br />
element is present as Cr(III) and iron as Fe 2+ (Fe(II), ferrous state). For incorporation in iron alloys,<br />
chromite is simply reduced with carbon in an electric arc furnace where ferrochrome - also known as<br />
ferro<strong>chromium</strong>, an alloy of iron and approximately 50-70 % <strong>chromium</strong> - is concurrently generated:<br />
EFSA Journal 2014;12(3):3595 11