Guidelines for Metals and Metalloids in Ambient ... - ARCHIVE: Defra

Expert Panel on Air Quality Standards
5.1.4 Human exposures
240. Non-occupational human exposures to chromium are difficult to
quantify. Exposure is widespread due to occurrence in air, water and
soil. It is present in essentially all biological materials that have been
examined, and thus is also consumed in food, although the trend to
consumption of highly processed foods has led to a reduced intake by
this route. This, coupled with the consumption of relatively high levels
of sugar (which stimulates excretion of chromium) may lead to
potentially serious dietary deficiency of chromium (Anderson, 1981).
241. Intake of chromium in the diet accounts for most of the nonoccupational
exposure. The wide variation in chromium content of
food is the main reason for the difficulty in estimating intakes overall.
Foods rich in chromium include meat, vegetables and unrefined sugar
while fish, vegetable oils and fruit contain smaller amounts. The most
available form of chromium in the diet is found in yeast, liver and
meats (Langård and Norseth, 1979).
242. Chromium concentrations in drinking water have been measured in
several countries and are almost always below (often well below) 0.005
mg/l. Thus an adult consuming 2 l/day would derive no more than 0.01
mg/day of chromium from this source. Dietary chromium is normally
considered to be in the Cr(III) form as Cr(VI) is reduced in the
presence of organic material. The speciation in drinking water is less
certain; at least some of the intake from this source could be in the
form of Cr(VI).
243. Wind blown soils and dusts provide a source of chromium in the
atmosphere, but based on typical concentrations of chromium in
surface soils, these are unlikely to generate annual concentrations as
high as 1 ng/m 3 except in areas of significant industrial contamination.
244. Although chromium is present in cigarettes at up to 390 µg/kg
(Schroeder et al., 1962) there are no published estimates of total intake
from this source. However assuming complete absorption from 25 g
tobacco daily, this would account for 10 µg/day, so it is unlikely that
this will contribute significantly to the overall intake. However, it
should be noted that this is possibly in the Cr(VI) form and in this
context may be significant. Other potential sources such as wood
preservatives, pica and residence in neighbourhoods with industrial
contamination are only minor contributors to exposure. In the UK
average daily intakes from ambient air are estimated to range from
0.0001 to 0.0006 µg/day, (based on values from DETR, 1997), but this
may include a proportion of Cr(VI).
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