efsa-opinion-chromium-food-drinking-water

Chromium in food and drinking water
average found at a few mg/kg levels. Rare crocoite (PbCrO 4 ) is the only mineral where Cr(VI) occurs
naturally. Soils from the weathering of basalt, serpentine and ultramafic rocks, and phosphorites may
contain chromium at levels as high as 3500 mg/kg, whereas soils from degradation of granite or
sandstone rocks normally have chromium only at levels of a few tens of mg/kg. Chromium
concentrations in thousands of USA and Canadian soil samples were reported to range from 1 to
2000 and from 5 to 1500 mg/kg, respectively, with corresponding geometric means of 37 and
43 mg/kg (WHO, 1988; ATSDR, 2012). Examples of hot spots can be found, for instance associated
with old chromite mining sites; chromium has also been detected at a very high level (43 000 mg/kg)
in soil at the Butterworth Landfill site in Grand Rapid City, Michigan. The use of chromated copper
arsenate (CCA) as an outdoor wood preservative may be a cause for soil contamination. In 1994 and
1995, chromium was detected in sediments obtained from the coastal waters of the eastern U.S.
seashore at concentrations lower than 0.2 mg/g (Hyland et al., 1998).
Examples of Cr(VI) occurrence from incidental anthropogenic sources
As human exposure to toxic Cr(VI) compounds, several of which are quite soluble, is a matter of
health concern, investigations and monitoring activities have been and are performed in different parts
of the world, especially focused on assessing the chemical presence and levels in drinking water and
its sources. From the generic examples described hereafter, drinking water seems to be the matrix of
concern with respect to a potential human exposure deriving from an undetected accidental
contamination.
An accidental release of Cr(VI) from a chemical plant into the atmosphere occurred in August 2011 in
Kooragang Island (Newcastle, New South Wales). The aerosol emission carrying Cr(VI) was
deposited downwind of the stack, mostly on and around the facility. The spill continued for
approximately 20 minutes. The original Cr(VI) emission estimate of 10-20 kg was subsequently
revised to an estimated 1 kg of Cr(VI) which, in fact, rained down over the Orica plant; another
35-60 g fell out over the suburb of Stockton (Orica, 2012), whose residents were therefore potentially
exposed to the contaminated aerosol. Approximately 20 workers at the plant were exposed as well as
70 nearby homes in Stockton.
The contamination of drinking water in the southern California town of Hinkley ensued from a
prolonged groundwater contamination (EWG, 2005; Sutton, 2010). At the center of the case was a
facility called the Hinkley compressor station, part of a long natural gas pipeline. Between 1952 and
1966, the compressor station used water containing Cr(VI) compounds to fight corrosion in the
machinery. Some Cr(VI)-contaminated wastewater, discharged to unlined ponds at the site, percolated
into the groundwater, affecting a large area near the plant. Average background Cr(VI) levels in
groundwater were recorded as 1.2 µg/L (total chromium 1.5 µg/L) with a peak of 3.1 µg/L (total
chromium 3.2 µg/L) (PG&E, 2007; CA EPA, 2008).
A contaminated groundwater plume originating from unknown source(s) allegedly composed of
hazardous substances that were released into the Edwards-Trinity aquifer was detected at Midland
(Texas), a community of approximately 114 000 people. At the time of the report by Cook (2010), the
plume had an extension of a few kilometres and was situated under approximately 105 ha of
residential and commercial land. Based on the results of a domestic drinking water well, an extensive
groundwater sampling was performed in 2009. The groundwater plume contained elevated
concentrations of total chromium including Cr(VI), that exceeded the U.S. EPA maximum
contaminant limit (MCL) of 0.1 mg/L for total chromium and Cr(VI) in many active domestic water
wells: in particular, a large proportion of samples contained total chromium and/or Cr(VI) forms in the
range 500-5000 µg/L.
According to Vasilatos et al. (2008), total chromium and Cr(VI) were measured in the Thiva-Tanagra-
Malakasa basin, Eastern Sterea Hellas, Greece. In the area, which is known for a 40-year long
industrial activity, chromium levels as high as 80 and 53 µg/L were found in the urban drinking water
supplies of Oropos and Inofyta, respectively. The pollution of groundwater by Cr(VI) in the majority
of water wells in the Thiva-Tanagra-Malakasa basin was related to the widespread industrial activity,
the use of hexavalent chromium in various processes, and the discharges of Cr-containing wastes. In
another study (Vasilatos et al., 2010), hexavalent chromium was detected in groundwater systems in
EFSA Journal 2014;12(3):3595 19