efsa-opinion-chromium-food-drinking-water

Chromium in food and drinking water
In soil, Cr(III) predominates, likely as insoluble hydrated Cr 2 O 3 forms: in addition to a direct release
as a result of anthropogenic activities, trivalent chromium can easily arise from reduction of Cr(VI)
species due to the presence of reductants. Chromium is lost from soil primarily due to physical
processes. For instance, chromium-containing soil particles can be raised by air draughts and dispersed
over long distances; likewise, runoff can remove from topsoil chromium ions and bulk precipitates of
the metal. Flooding of soils and the subsequent decomposition of vegetal matter may also increase
dissolution of soil-borne Cr 2 O 3 through the formation of water-soluble chromium complexes which
will possibly leach and percolate through soil (U.S. EPA, 1998a, b; WHO, 2003).
A study was conducted in 1991 to determine the levels of heavy metals and polycyclic aromatic
hydrocarbons (PAHs) in soil along a busy road that runs through the Aplerbecker forest near the
German town of Dortmund. Background concentrations of the metals were reached some 5-10 m away
from the road. The concentration of chromium in the soil at the edge of the road showed a two- to
four-fold increase relative to background levels, reaching up to 64 mg/kg (Münch, 1993). The thick
vegetation structure of the forest and its barrier effect was discussed as a reason for the heavy
accumulation of the metals and PAHs detected in the roadside soil.
The bioconcentration factor (BCF) for chromium in rainbow trout (Salmo gairdneri) was reported
as 1. In bottom-feeder bivalves, such as the oyster (Crassostrea virginica), blue mussel (Mytilus
edulis), and soft shell clam (Mya arenaria), chromium BCF values were found to be in the order of
10 2 . Based on experimental observations, chromium is not expected to biomagnify in the aquatic food
chain (U.S. EPA, 1998a, b; OEHHA, 2011; ATSDR, 2012). Higher chromium concentrations were
found in plants growing in soils with high chromium contents compared with plants growing in
normal soils: however, as only a small fraction of chromium is translocated from soil to the epigeal
parts of edible plants, bioaccumulation of chromium from soil to the aforesaid plant parts is unlikely.
There is no indication of chromium biomagnification along the terrestrial food chain.
1.2.2. Sources of food and drinking water contamination
Chromium can enter the food chain via the different environmental compartments, either as a result of
natural presence or emission from anthropogenic activities. Food preparation with stainless steel
containers, processors and utensils could represent an additional source for the presence of chromium
in food (Stoewsand et al., 1979; Offenbacher and Pi-Sunyer, 1983; Kumpulainen, 1992).
Environmental levels
According to studies from the late 1970s onwards (WHO, 2000, 2003), air chromium concentrations
in the range of 0.005-1.1 ng/m 3 were detected in various remote locations such as the Arctic and
Antarctic poles, north Atlantic ocean, Shetland Islands, Norway, and northwest Canada; in remote
European areas, concentrations up to 3 ng/m 3 were measured. Health Canada (1986) reported
chromium concentrations in air samples from five remote areas in Canada between 0.32 and 25 ng/m 3 ,
while in the USA chromium concentrations in urban air were reported from less than 10 to 50 ng/m 3 .
Most environment monitoring stations in the USA detected average chromium levels in ambient air of
rural and urban areas below 300 ng/m 3 (median, < 20 ng/m 3 ), although occasional measurements could
be higher (WHO, 2000, 2003). The mean concentration of chromium in air in the Netherlands
appeared to vary in the range of 2 to 5 ng/m 3 ; in continental Europe, air chromium concentrations were
found to span 1-140 ng/m 3 , a range comprising urban area values (4-70 ng/m 3 ). In industrial European
settings, air chromium concentrations were in the range 5-200 ng/m 3 . The air chromium levels in
Japan and Hawaii were found to be in the range 20-70 ng/m 3 (WHO, 2000). In general, in nonindustrialized
areas concentrations above 10 ng/m 3 were uncommon whereas in urban areas they were
two to four times higher than regional background concentrations (WHO, 2003; OEHHA, 2011). As a
result of smoking, chromium concentrations in indoor air (≈ 1000 ng/m 3 ) may be 10-400 times greater
than outdoor concentrations (WHO, 2003). Chromium concentrations in rainwater showed a marked
variability (for example, see: van Daalen, 1991; Neal et al., 1996; Kaya and Tuncel, 1997); however,
on average they were found to be in the range 0.2-1 µg/L (WHO, 2003). Cr(VI) forms may be present
in rainwater (Seigneur and Constantinou, 1995): for instance, chromium species were determined in
several rainwater samples collected in North Carolina in 1999 through 2001 (Kieber et al., 2002). The
EFSA Journal 2014;12(3):3595 17