Number 58 March 1995
MAFF UK - BENZENE AND OTHER AROMATIC HYDROCARBONS IN FOOD- AVERAGE UK
DIETARY INTAKES
Index to MAFF UK Food Surveillance Information
Sheets, 1995
See also:
38: MAFF UK - Survey of Styrene in
Food (October 1994)
98: MAFF UK - Hydrocarbons in Foods
from Shops in Petrol Stations and Stalls or Shops in Busy Roads (October
1996)
141: MAFF UK - Chlorobenzenes in
Foods (February 1998)
189: MAFF UK - Total Diet Study:
Styrene (November 1999)
Summary
MAFF has recently carried out a survey of benzene, toluene, ethylbenzene
and xylenes in Total Diet Study samples collected in 1993. Results show
that average UK dietary intakes of toluene are 7.7 µg/day. Benzene,
ethylbenzene and xylenes were found in only a few of the samples and
estimates for the intakes of these compounds are less exact. The average
UK dietary intake of benzene is less than 2.4 µg/day; the average
intakes of ethylbenzene and xylenes are each less than 5 µg/day.
Background
Benzene has recently been evaluated by the UK Committee on
Carcinogenicity of Chemicals in Food, Consumer Products and the
Environment. The Committee concluded that benzene was genotoxic and had
been shown to induce leukaemia in some humans exposed to relatively high
occupational levels. There are less toxicological data for toluene,
ethylbenzene and xylenes. All these simple aromatic hydrocarbons are
common environmental contaminants. This survey was conducted to estimate
the average UK dietary intakes of these compounds and to compare these
intakes with human exposure from other sources.
Benzene and other simple aromatic hydrocarbons are important raw
materials and intermediates in the synthesis of a wide range of more
complex chemicals, such as polyurethane, nylon, pharmaceuticals and dyes.
In addition, aromatic hydrocarbons are constituents of fuels - petrol
typically contains 3 percent benzene, 1 percent toluene ,4 percent xylenes
and 2 percent ethylbenzene. Toluene and xylenes are also commonly used as
solvents in paints and coatings.1
The majority (90 percent) of the total amount of benzene released to the
atmosphere in the UK arises from road transport exhaust gases. Road
transport also makes a large contribution (50 percent) to releases of
toluene, but is a less important source (10 - 17 percent of releases to
atmosphere) of ethylbenzene and xylenes, for which industrial solvent use
is the major source. As a result of their wide range of uses and their
potential for loss to the environment, aromatic hydrocarbons have been
reported in air and surface water throughout industrialised nations.1
Once released to the atmosphere, aromatic hydrocarbons may enter foods via
a number of routes, including direct absorption from the atmosphere by
fatty foods at different points of the food supply chain.
This survey analysed Total Diet Study (TDS) samples of all twenty food
groups collected from 10 of the UK locations included in the study in
1993. Each TDS food group consists of retail food products, prepared as
for consumption and then combined in amounts reflecting their relative
importance in the average UK diet. Analysis of these samples has allowed
average UK dietary intakes of these aromatic hydrocarbons to be estimated.
Results
The food samples were analysed by static headspace gas chromatography
with mass spectrometric detection at CSL Food Science Laboratory, Norwich.
The limit of determination of the method was 1 µg/kg for benzene and
toluene, and 2 µg/kg for ethylbenzene, p/m-xylene, and o-xylene.
The average intake of each of the aromatic hydrocarbons from each of the
food groups was calculated by multiplying the concentration of the
chemical in that food group sample by the amount of that food group eaten
in a day by an average UK consumer. Total dietary intakes were then
estimated by summing the contributions of all twenty food groups.
Aromatic hydrocarbons were not present above the limit of determination
(LOD) in many of the food group samples (see Table 1).
For each chemical, two estimates of dietary intakes were made. First,
dietary intakes were calculated assuming that the chemical was present at
the LOD in any food group sample in which it was undetectable. Second,
dietary intakes were calculated assuming that the concentration of the
chemical was zero in any food group sample in which it was undetectable.
These calculations give 'upper bound' and 'lower bound' estimates of the
true average dietary intake, respectively (see Table
2). The average dietary intake will be between these two figures.
Toluene was present in most food group samples analysed. The average UK
dietary intake of toluene was estimated to be 7.7 µg/person/day, with
the largest contributions to this intake being made by milk (14 percent of
total), milk products (13 percent of total) and beverages (12 percent of
total).
Benzene, ethylbenzene and xylenes were detected in most samples of
carcase meat, offal, meat products, poultry, fish and nuts, but were not
detected in most samples of other food groups. The average UK dietary
intake of benzene is less than 2.4 µg/person/day; the average intakes
of ethylbenzene and xylenes are each less than 5 µg/person/day.
Interpretation
The average concentrations of aromatic hydrocarbons found in composite
TDS samples were low and, for many samples, below the limit of
determination. No UK Tolerable Daily Intakes have been set for benzene,
toluene, ethylbenzene or xylenes in food.
The estimated total annual releases of toluene to the UK environment are
similar to estimated releases of o-xylene and ethylbenzene, and
significantly less than estimated releases of p/m-xylene. However,
the incidence and concentrations of toluene measured in the TDS samples
were higher than the incidence and concentrations of the other aromatic
hydrocarbons. This suggests that other factors, such as rate of
environmental degradation, are also important in determining
concentrations of these compounds in food.
The average UK dietary intake of benzene was estimated to be in the
range 0.5 - 2.4 µg/person/day. This estimate is similar to that of
1.2 µg/person/day for the intake of benzene by Canadian adults from
food.2 The average intakes of benzene
from food are very much lower than the estimated daily exposure to benzene
from active smoking of tobacco, or intakes from air by urban dwellers.3,4
Urban air concentrations of xylenes, toluene and ethylbenzene are similar
to concentrations of benzene, and the vast majority of exposure of the
general population to these other aromatic hydrocarbons will be due to
road transport or solvent-containing products rather than food.1,
4,5
References
- Nielsen, I.R. & Howe, P.D. (1991). Environmental
Hazard Assessment: Toluene. TSD/1. Neilsen, I.R.; Rea,
J.D. & Howe, P.D. (1991) Environmental Hazard Assessment:
Benzene. TSD/4. Crookes, M.J. & Howe, P.D. (1992)
Environmental Hazard Assessment: Ethylbenzene. TSD/7.
Crookes, M.J.; Dobson, S. & Howe, P.D. (1993) Environmental
Hazard Assessment: Xylenes. TSD/12. All available from the
Building Research Establishment, Watford.
- Holliday, M.G. & Park, J.M. (1989). Exposure of
Canadians to benzene. Unpublished document by Michael Holliday and
Associates prepared for the Environmental Health Directorate, Department
of National Health and Welfare, Ottawa.
- Wallace, L.A. (1989). Major sources of benzene
exposure. Environ. Health Perspect. 82:165-169.
- Howard, P.H. (1990). In Handbook of Fate and
Exposure Data for Organic Chemicals. Volume II - Solvents. Lewis
Publishers, Chelsea, Michigan.
- Anon (1982). Alkyl Benzenes. IRPTC Bull.
5:17-18. Anon (1987) Toluene. IRPTC Bull. 8:35-37.
Contact point
For further information, please contact:
Dr Nigel Harrison,
MAFF, Joint Food Safety and Standards Group,
Food Contaminants Division,
Room 234 Ergon House, c/o Nobel House,
17 Smith Square
London SW1P 3JR
Tel: +44 (0)20 7238 6235
Fax: +44 (0)20 7238 5331
Return to Index to Surveillance Information Sheets, 1995 page
Go to top of page
These pages were last updated on 1 October 1996
