efsa-opinion-chromium-food-drinking-water

Chromium in food and drinking water
ATSDR noted that neither the chemical form nor the amount of chromium in tobacco smoke is
known, and that people who use tobacco products may be exposed to higher-than-normal levels of
chromium (ATSDR, 2012).
The CONTAM Panel could not quantify the contribution of non-dietary exposure to Cr(III) or Cr(VI)
due to the existing uncertainties on the levels of exposure via inhalation, the absorption rates of
different chromium compounds via the respiratory system and the relevance of different chromium
species for non-dietary exposure.
The CONTAM Panel concluded that exposure via the diet likely represents the most important
contribution to the overall exposure to Cr in the general population. Inhalation of Cr compounds
present in particular in cigarette smoke may contribute to the overall exposure levels but the currently
available information dose not allow quantification of its relative contribution.
7. Hazard identification and characterisation
7.1. Toxicokinetics
Several previous evaluations provide information on the toxicokinetics of Cr(III) and Cr(VI) (U.S.
EPA 1998a, b; WHO, 1996a, 2000, WHO/IPCS 2009a, 2013; EFSA 2008a, EFSA ANS Panel
2010a,b). The Sections below summarise this information while presenting recent additional data in
more detail.
The toxicokinetics of chromium appear to depend on the oxidation state. Hexavalent chromium
readily penetrates cell membranes whereas trivalent chromium does not.
7.1.1. Trivalent Chromium
Absorption
Following oral administration, Cr(III) was reported to be very poorly absorbed via the gastrointestinal
tract (0.4 to 2.8 %) in both rats and humans (Conn et al., 1932; Visek et al., 1953; Donaldson and
Barreras, 1966; Doisy et al., 1971; Henderson et al., 1979; Anderson et al., 1983; Aitio et al., 1984;
Anderson and Kozlovsky, 1985; Polansky et al., 1993; Gargas et al., 1994; Olin et al., 1994; Kerger et
al., 1996; Gammelgaard et al., 1999; ATSDR, 2012; Febel et al., 2001; Garcia et al., 2001).
The rate of uptake of chromium compounds in the gastrointestinal tract may be governed by the water
solubility of the compounds (Langård, 1982; WHO, 2000). WHO indicated that a fractional absorption
value of 5 % is considered to be a good estimate for the gastrointestinal absorption of soluble
inorganic chromium compounds, but 0.5 % is more appropriate for that of insoluble inorganic
chromium compounds such as chromic trioxide pigment (WHO, 1996a).
Some studies have revealed that there can be differences in the bioavailability and tissue levels of
chromium resulting from intake of different forms of chromium compounds (U.S. Patent
5.194.615,1993; Olin et al., 1994; Lamson and Plaza, 2002). Differences in bioavailability of Cr(III)
have been reported depending on the ionic form and/or the organic or the inorganic forms of the
Cr(III). Organic forms of Cr(III) might be better absorbed than inorganic Cr(III) (Mertz, 1969; Vinson
and Bose, 1984; Olin et al., 1994; Lamson and Plaza, 2002).
Studies on rats found that the ranking of the relative absorption and retaining of trivalent chromium
from different sources was chromium nicotinate > chromium picolinate > chromium chloride (Lamson
and Plaza, 2002). In their opinion on chromium picolinate, zinc picolinate and zinc picolinate
dihydrate added for nutritional purposes in food supplements the EFSA ANS Panel noted that the
bioavailability of inorganic Cr(III) is generally very low (0.1-2 %) and that the bioavailability of
chromium from chromium picolinate may be higher because complex formation may influence the
chromium bioavailability and that chromium from chromium picolinate is equally or slightly more
bioavailable than chromium from other chromium compounds (EFSA, 2009b).
EFSA Journal 2014;12(3):3595 62