UNITED NATIONS ENVIRONMENT PROGRAMME
INTERNATIONAL LABOUR ORGANISATION
WORLD HEALTH ORGANIZATION
INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
ENVIRONMENTAL HEALTH CRITERIA 171
DIESEL FUEL AND EXHAUST EMISSIONS
This report contains the collective views of an international group of
experts and does not necessarily represent the decisions or the stated
policy of the United Nations Environment Programme, the International
Labour Organisation, or the World Health Organization.
Environmental Health Criteria 171
DIESEL FUEL AND EXHAUST EMISSIONS
First draft prepared by the staff members of the Fraunhofer Institute
of Toxicology and Aerosol Research, Germany, under the coordination of
Dr. G. Rosner
Published under the joint sponsorship of the United Nations
Environment Programme, the International Labour Organisation, and the
World Health Organization, and produced within the framework if the
Inter-Organization Programme for the Sound Management of Chemicals.
World Health Organization
Geneva, 1996
The International Programme on Chemical Safety (IPCS) is a joint
venture of the United Nations Environment Programme, the International
Labour Organisation, and the World Health Organization. The main
objective of the IPCS is to carry out and disseminate evaluations of
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environment. Supporting activities include the development of
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that could produce internationally comparable results, and the
development of manpower in the field of toxicology. Other activities
carried out by the IPCS include the development of know-how for coping
with chemical accidents, coordination of laboratory testing and
epidemiological studies, and promotion of research on the mechanisms
of the biological action of chemicals.
WHO Library Cataloguing in Publication Data
Diesel Fuel and exhaust emission
(Environmental health criteria ; 171)
1.Air pollutants, Enviromental 2.Air pollution 3.Fueloils
I.International Programme on Chemical Safety II.Series
ISBN 92 4 157171 3 (NLM Classification: WA 754)
ISSN 0250-863X
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CONTENTS
NOTE TO READERS OF THE CRITERIA MONOGRAPHS
PREAMBLE
ENVIRONMENTAL HEALTH CRITERIA FOR DIESEL FUEL AND EXHAUST EMISSIONS
WHO DRAFTING GROUP ON ENVIRONMENTAL HEALTH CRITERIA FOR DIESEL FUEL
AND EXHAUST EMISSIONS
WHO TASK GROUP ON ENVIRONMENTAL HEALTH CRITERIA FOR DIESEL FUEL AND
EXHAUST EMISSIONS
PART A: DIESEL FUEL
A1. SUMMARY
A1.1 Identity, physical and chemical properties, and
analytical methods
A1.2 Sources of human and environmental exposure
A1.3 Environmental transport, distribution, and
transformation
A1.4 Environmental levels and human exposure
A1.5 Effects on laboratory mammals and in vitro test
systems
A1.6 Effects on humans
A1.7 Effects on other organisms in the laboratory and the
field
A1.8 Evaluation of human health risks
A1.9 Evaluation of effects on the environment
A2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, AND ANALYTICAL
METHODS
A2.1 Identity
A2.1.1 Fuel components
A2.1.1.1 Alkanes
A2.1.1.2 Alkenes
A2.1.1.3 Aromatic compounds
A2.1.1.4 Sulfur
A2.1.2 Fuel additives
A2.1.2.1 Cetane number improvers
A2.1.2.2 Smoke suppressors
A2.1.2.3 Flow improvers
A2.1.2.4 Cloud-point depressors
A2.1.2.5 Wax anti-settling additives
A2.1.2.6 Other additives
A2.1.3 Quality aspects of diesel fuels
A2.1.3.1 Ignition performance and cetane
number
A2.1.3.2 Density
A2.1.3.3 Sulfur content
A2.1.3.4 Viscosity
A2.1.3.5 Cold-flow properties
A2.2 Physical and chemical properties
A2.3 Analytical methods
A2.4 Conversion factors
A3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
A3.1 Natural occurrence
A3.2 Anthropogenic sources
A3.2.1 Production and use
A3.2.1.1 Production process
A3.2.1.2 Use
A3.2.1.3 Production and consumption
levels
A3.2.2 Emissions during production and use
A3.2.2.1 Air
A3.2.2.2 Water
A3.2.2.3 Soil
A3.2.3 Accidental releases to the environment
A4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
A4.1 Transport and distribution between media
A4.1.1 Evaporation from and dissolution in the
aqueous phase
A4.1.2 Transport in and adsorption onto soil and
sediment
A4.1.2.1 Soil
A4.1.2.2 Sediment
A4.2 Transformation and removal
A4.2.1 Photooxidation
A4.2.2 Biodegradation
A4.2.2.1 Microbial degradation
A4.2.2.2 Phytoplankton and marine algae
A4.2.2.3 Invertebrates and vertebrates
A4.2.3 Bioaccumulation
A4.2.4 Tainting
A4.2.5 Entry into the food chain
A4.3 Ultimate fate after use
A4.3.1 Use in motor vehicles
A4.3.2 Spills
A4.3.3 Disposal
A5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
A5.1 Environmental levels
A5.2 Exposure of the general population
A5.3 Occupational exposure during manufacture,
formulation, or use
A6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS
A7. EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS
A7.1 Single exposure
A7.2 Short-term exposure
A7.2.1 Subacute exposure
A7.2.1.1 Dermal exposure
A7.2.1.2 Inhalation
A7.2.2 Subchronic exposure
A7.2.2.1 Dermal exposure
A7.2.2.2 Inhalation
A7.3 Long-term exposure
A7.3.1 Dermal exposure
A7.3.2 Inhalation
A7.4 Dermal and ocular irritation; dermal sensitization
A7.4.1 Dermal irritation
A7.4.2 Ocular irritation
A7.4.3 Sensitization
A7.5 Reproductive toxicity, embryotoxicity, and
teratogenicity
A7.6 Mutagenicity and related end-points
A7.6.1 In vitro
A7.6.2 In vivo
A7.7 Carcinogenicity
A7.7.1 Dermal exposure
A7.7.2 Inhalation
A8. EFFECTS ON HUMANS
A8.1 Exposure of the general population
A8.2 Occupational exposure
A9. EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND THE FIELD
A9.1 Laboratory experiments
A9.1.1 Microorganisms
A9.1.1.1 Water
A9.1.1.2 Soil
A9.1.2 Aquatic organisms
A9.1.2.1 Plants (phytoplankton)
A9.1.2.2 Invertebrates
A9.1.3 Terrestrial organisms
A9.1.3.1 Plants
A9.1.3.2 Invertebrates
A9.1.3.3 Vertebrates
A9.2 Field observations
A9.2.1 Microorganisms.
A9.2.1.1 Water
A9.2.1.2 Soil
A9.2.2 Aquatic organism
A9.2.3 Terrestrial organisms
A9.2.3.1 Plants
A9.2.3.2 Invertebrates
A9.2.3.3 Vertebrates
A10. EVALUATION OF HUMAN HEALTH RISKS AND EFFECTS ON THE
ENVIRONMENT
A10.1 Evaluation of human health risks
A10.1.1 Exposure of the general population
A10.1.2 Occupational exposure
A10.1.3 Non-neoplastic effects
A10.1.4 Neoplastic effects
A10.2 Evaluation of effects on the environment
A11. RECOMMENDATIONS
A11.1 Recommendations for the protection of human health
A11.2 Recommendation for the protection of the environment
A11.3 Recommendations for further research
A12. PREVIOUS EVALUATIONS BY INTERNATIONAL BODIES
PART B: DIESEL EXHAUST EMISSIONS
B1. SUMMARY
B1.1 Identity, physical and chemical properties, and
analytical methods
B1.2 Sources of human and environmental exposure
B1.3 Environmental transport, distribution, and
transformation
B1.4 Environmental levels and human exposure
B1.5 Kinetics and metabolism in laboratory animals and
humans
B1.5.1 Deposition
B1.5.2 Retention and clearance of particles
B1.5.3 Retention and clearance of polycyclic
aromatic hydrocarbons adsorbed onto diesel
soot
B1.5.4 Metabolism
B1.6 Effects on laboratory mammals and in vitro test
systems
B1.7 Effects on humans
B1.8 Effects on other organisms in the laboratory and the
field
B1.9 Evaluation of human health risks
B1.9.1 Non-neoplastic effects
B1.9.2 Neoplastic effects
B1.10 Evaluation of effects on the environment
B2. IDENTITY AND ANALYTICAL METHODS
B2.1 Identity
B2.1.1 Chemical composition of diesel exhaust
gases
B2.1.2 Type and composition of emitted particulate
matter
B2.2 Analytical methods
B2.2.1 Sampling
B2.2.1.1 Sampling from undiluted exhaust
gas (raw gas sampling)
B2.2.1.2 Sampling from diluted exhaust
(dilution tube sampling)
B2.2.2 Extraction from particles
B2.2.3 Clean-up and fractionation
B2.2.4 Chemical analysis
B2.3 Conversion factors
B3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
B3.1 Anthropogenic sources
B3.1.1 Diesel exhaust emissions
B3.1.1.1 Emission of chemical
constituents with the gaseous
portion of diesel exhaust
B3.1.1.2 Emission of particulate matter
and adsorbed components in
diesel exhaust gases
B3.1.2 Parameters that influence diesel exhaust
emissions
B3.1.2.1 Engine conditions
B3.1.2.2 Fuel specification
B3.1.2.3 Malfunction
B3.1.3 Total emissions by diesel engines
B3.1.4 Control of emissions
B3.1.4.1 Particle traps
B3.1.4.2 Catalytic converters
B3.2 Regulatory approaches
B4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
B4.1 Transport and distribution between media
B4.2 Transformation and removal
B5. ENVIRONMENTAL LEVELS AND HUMAN EXPOSURE
B5.1 Exposure of the general population
B5.2 Occupational exposure
B5.2.1 Truck drivers and mechanics
B5.2.2 Bus garage and other bus workers
B5.2.3 Fork-lift truck operators
B5.2.4 Railroad workers
B5.2.5 Mine workers
B5.2.6 Fire fighters
B5.3 Biomonitoring
B5.3.1 Urinary mutagenicity
B5.3.2 Other analyses
B6. KINETICS AND METABOLISM IN LABORATORY ANIMALS AND HUMANS
B6.1 Deposition
B6.2 Retention and clearance of particles
B6.3 Retention and clearance of polycyclic aromatic
hydrocarbons adsorbed onto diesel soot
B6.4 Metabolism
B7. EFFECTS ON LABORATORY MAMMALS AND IN VITRO TEST SYSTEMS
B7.1 Single exposure
B7.2 Short-term exposure
B7.3 Long-term exposure and studies of carcinogenicity
B7.3.1 Non-neoplastic effects
B7.3.2 Carcinogenicity
B7.3.2.1 Inhalation
B7.3.2.2 Other routes of exposure
B7.4 Dermal and ocular irritation; dermal sensitization
B7.5 Reproductive toxicity, embryotoxicity, and
teratogenicity
B7.5.1 Reproductive toxicity
B7.5.2 Embryotoxicity
B7.5.3 Teratogenicity
B7.6 Mutagenicity and related end-points
B7.6.1 In vitro
B7.6.2 In vivo
B7.6.3 DNA adduct formation
B7.7 Special studies
B7.7.1 Immunotoxicity
B7.7.2 Behavioural effects
B7.8 Factors that modify toxicity; toxicity of
metabolites
B7.9 Mechanisms of toxicity; mode of action
B7.9.1 Carcinogenic effects
B7.9.1.1 DNA-reactive mechanisms
B7.9.1.2 Cytotoxicity with regenerative
cell proliferation
B7.9.1.3 Effects of particles
B7.9.1.4 Effects of polycyclic aromatic
hydrocarbons
B7.9.2 Noncarcinogenic effects
B8. EFFECTS ON HUMANS
B8.1 General population
B8.1.1 Acute exposure: olfactory, nasal, and
ocular irritation
B8.1.2 Air pollution
B8.2 Occupational exposure
B8.2.1 Effects on the respiratory system
B8.2.1.1 Symptoms
B8.2.1.2 Acute changes in pulmonary
function
B8.2.1.3 Pulmonary effects
B8.2.2 Epidemiological studies (noncarcinogenic
effects)
B8.2.2.1 Effects on the respiratory
system
B8.2.2.2 Effects on the circulatory
system
B8.2.3 Epidemiological studies (carcinogenic
effects)
B8.2.3.1 Lung cancer
B8.2.3.2 Urinary bladder cancer
B9. EFFECTS ON OTHER ORGANISMS IN THE LABORATORY AND THE FIELD
B10. EVALUATION OF HUMAN HEALTH RISKS AND EFFECTS ON THE
ENVIRONMENT
B10.1 Exposure of the general population
B10.2 Occupational exposure
B10.3 Non-neoplastic effects
B10.3.1 Hazard identification
B10.3.1.1 Humans
B10.3.1.1 Experimental animals
B10.3.2 Dose-response assessment
B10.3.2.1 Epidemiological studies
B10.3.2.2 Studies in experimental animals
B10.3.3 Exposure assessment
B10.3.4 Risk characterization
B10.3.4.1 Humans
B10.3.4.2 Experimental animals
B10.4 Neoplastic effects
B10.4.1 Hazard identification
B10.4.1.1 Lung cancer: occupational
exposure
B10.4.1.2 Urinary bladder cancer:
occupational exposure
B10.4.2 Dose-response assessment
B10.4.2.1 Lung cancer
B10.4.2.2 Urinary bladder cancer
B10.4.3 Exposure assessment
B10.4.4 Risk characterization
B10.4.4.1 Human lung cancer
B10.4.4.2 Human urinary bladder cancer
B10.4.4.3 Risk characterization based on
studies in experimental animals
Appendix B10.1 Construction of a biologically
based (alternative) model
Appendix B10.2 E-M algorithm
Appendix B10.3 A tumour growth model
B11. RECOMMENDATIONS
B11.1 Recommendations for the protection of human health
B11.2 Recommendation for the protection of the environment
B11.3 Recommendations for further research
B12. PREVIOUS EVALUATIONS BY INTERNATIONAL BODIES
REFERENCES
RESUMÉ
RESUMEN
NOTE TO READERS OF THE CRITERIA MONOGRAPHS
Every effort has been made to present information in the Criteria
monographs as accurately as possible without unduly delaying their
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International Register of Potentially Toxic Chemicals, Case postale
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This publication was made possible by grant number 5 U01
ES02617-15 from the National Institute of Environmental Health
Sciences, National Institutes of Health, USA, and by financial support
from the European Commission.
Environmental Health Criteria
PREAMBLE
Objectives
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WHO DRAFTING GROUP ON ENVIRONMENTAL HEALTH CRITERIA FOR DIESEL FUEL
AND EXHAUST EMISSIONS
WHO, Geneva, 6-9 December 1993
Members
Dr J.A. Bond, Chemical Industry Institute of Toxicology, Research
Triangle Park, NC, United State
Dr R.P. Bos, University of Nijmegen, Nijmegen, Netherlands
Dr R. Brown, Medical Research Council Toxicology Unit, University of
Leicester, Leicester, United Kingdom (Joint Rapporteur)
Dr Chao Chen, Human Health Assessment Group, United States
Environmental Protection Agency, Washington DC, United States
Dr I. Farkas, National Institute of Hygiene, Budapest, Hungary
Dr E. Garshick, Pulmonary Section, Brockton/West Roxbury VA Medical
Center, West Roxbury, MA, United States
Dr P. Gustavsson, North Western Health Board, Stockholm, Sweden
Dr D. Guth, United States Environmental Protection Agency, Research
Triangle Park, NC, United States
Dr U. Heinrich, Department of Experimental Hygiene, Fraunhofer
Institute of Toxicology and Aerosol Research, Hanover, Germany
Dr R.F. Hertel, Federal Health Office, Bundesgesundheitsamt, Berlin,
Germany
Professor G. Oberdörster, Department of Environmental Medicine,
University of Rochester Medical Center, Rochester, NY, United States
Dr W. Pepelko, United States Environmental Protection Agency,
Washington DC, United States
Dr P.J.A. Rombout, Laboratory of Toxicology, National Institute of
Public Health and Environmental Protection, Bilthoven, Netherlands
(Vice-Chairman)
Dr G. Rosner, Hazardous Substances Documentation Group, Fraunhofer
Institute of Toxicology and Aerosol Research, Hanover, Germany
Dr J. Roycroft, National Institute of Environmental Health Sciences,
Research Triangle Park, NC, United States
Dr A. Sivak, Environmental Health Sciences, Saint Augustine, FL,
United States (Chairman)
Dr B.H. Thomas, Environmental Health Directorate, Ottawa, Canada
Dr L. Turrio, Istituto Superiore di Sanita, Laboratorio Tossicologia
Comparata e Ecotossicologia, Rome, Italy
Mr. R. Waller, Department of Health, London, United Kingdom
Secretariat
Dr P. Boffetta, International Agency for Research on Cancer, Lyon,
France (6-7 December 1993)
Dr E. Smith, International Programme on Chemical Safety, World Health
Organization, Geneva, Switzerland
Representatives/Observers
CONCAWE
Dr R.H. McKee, Exxon Biomedical Sciences, East Millstone, NJ,
United States
UNITED KINGDOM DEPARTMENT OF THE ENVIRONMENT
Dr P.T.C. Harrison, MRC Institute of Environment & Health,
Leicester, United Kingdom
WHO TASK GROUP ON ENVIRONMENTAL HEALTH CRITERIA FOR DIESEL FUEL AND
EXHAUST EMISSIONS
Fraunhofer Institute of Toxicology & Aerosol Research, Hanover
27 June-1 July 1994
Members
Dr J.A. Bond, Chemical Industry Institute of Toxicology, Research
Triangle Park, NC, United States
Dr R. Brown, Medical Research Council Toxicology Unit, University of
Leicester, Leicester, United Kingdom
Dr Chao Chen, Human Health Assessment Group, United States
Environmental Protection Agency, Washington DC, United States
Dr E. Garshick, Pulmonary Section, Brockton/West Roxbury VA Medical
Center, West Roxbury, MA, United States
Dr U. Heinrich, Department of Experimental Hygiene, Fraunhofer
Institute of Toxicology and Aerosol Research, Hanover, Germany
Dr R.F. Hertel, Federal Health Office, Bundesgesundheitsamt, Berlin,
Germany
Dr Jun Kagawa, Tokyo Women's Medical College, Tokyo, Japan
Professor G. Oberdörster, Department of Environmental Medicine,
University of Rochester Medical Center, Rochester, NY, United States
Dr P.J.A. Rombout, Laboratory of Toxicology, National Institute of
Public Health and Environmental Protection, Bilthoven, Netherlands
Dr M. Roller, Medizinishes Institut für Umwelthyglene an der
Universität Düsseldorf, Düsseldorf, Germany Dr G. Rosner, Hazardous
Substances Documentation Group, Fraunhofer Institute of Toxicology and
Aerosol Research, Hanover, Germany
Dr A. Sivak, Environmental Health Sciences, Saint Augustine, FL,
United States
Dr L. Turrio, Istituto Superiore di Sanita, Laboratorio Tossicologia
Comparata e Ecotossicologia, Rome, Italy
Mr R. Waller, Department of Health, London, United Kingdom
Secretariat
Dr H. Moller, International Agency for Research on Cancer, Lyon,
France
Dr E. Smith, International Programme on Chemical Safety, World Health
Organization, Geneva, Switzerland
Dr M. Younes, European Centre for Environment and Health, Bilthoven,
Netherlands
Representatives/Observers
Dr Lutz Von Meyerinck, BP Oil Europe, Brussels, Belgium
GERMAN AUTOMOBILE ASSOCIATION
Dr N. Pelz, Mercedes-Benz AG, Stuttgart, Germany
ILSI
Dr I.T. Salmeen, Chemistry Department, Ford Motor Company,
Dearborn, MI, United States
IUTOX
Dr P. Montuschi, Department of Pharmacology, School of Medicine,
Catholic University of the Sacred Heart, Rome, Italy
ENVIRONMENTAL HEALTH CRIETERIA FOR DIESEL FUEL AND EXHAUST EMISSIONS
A WHO Task Group on Environmental Health Criteria for Diesel Fuel
and Exhaust Emissions met at the Fraunhofer Institute of Toxicology
and Aerosol Research, Hanover, Germany from 27 June to 1 July 1994.
Dr G. Rosner, Fraunhofer Institute, welcomed the participants on
behalf of the Institute and its Director, Professor U. Mohr, and
Dr E.M. Smith, IPCS, welcomed the participants on behalf of
Dr M. Mercier, Director of the IPCS, and on behalf of the heads of the
three IPCS cooperating organizations (UNEP, ILO, and WHO). The Task
Group reviewed and revised the draft and evaluated the risks for human
health and the environment from exposure to diesel fuel and exhaust
emissions.
The first draft of the monograph was prepared at the Fraunhofer
Institute. After international circulation for comment, this draft was
extensively revised by a Working/Drafting Group, convened at WHO,
Geneva, from 6 to 9 December 1993, and a second draft was prepared for
further international circulation for comment. The membership of the
drafting group is shown previously. A final draft, incorporating
comments received from the IPCS contact points for Environmental
Health Criteria monographs and new material, was completed at the
Fraunhofer Institute under the coordination of Dr G. Rosner, with
important contributions to the text from the following Institute staff
members:
Dr B. Bellman
Dr A. Boehnke
Dr O. Creutzenberg
Dr J. Kielhorn
Dr E.M. Smith of the IPCS Central Unit was responsible for the
scientific content of the monograph and Mrs E. Heseltine, Lajarthe,
France, for the editing.
The efforts of all who helped in the preparation and finalization
of the monograph are gratefully acknowledged.
PART A DIESEL FUEL
A1. SUMMARY
A1.1 Identity, physical and chemical properties, and analytical
methods
Diesel fuel is a complex mixture of normal, branched, and cyclic
alkanes (60 to > 90% by volume; hydrocarbon chain length, usually
between C9 and C30); aromatic compounds, especially alkylbenzenes
(5-40% by volume); and small amounts of alkenes (0-10% by volume)
obtained from the middle-distillate, gas-oil fraction during petroleum
separation. Benzene, toluene, ethylbenzene, and xylenes and polycyclic
aromatic hydrocarbons (PAHs), especially naphthalene and its
methyl-substituted derivatives, may be present at levels of parts per
million in diesel fuel. The sulfur content of diesel fuels depends on
the source of crude oil and the refinery process. It is regulated by
law in a number of countries and is usually between 0.05 and 0.5
weight percent. Additives are used to influence the flow, storage, and
combustion of diesel fuel, to differentiate products, and to meet
trademark specifications. At room temperature, diesel fuels are
generally moderately volatile, slightly viscous, flammable, brown
liquids with a kerosene-like odour. The boiling ranges are usually
between 140 and 385°C (> 588°C for marine diesel fuel); at 20°C, the
density is 0.87-1.0 g/cm3 and the water solubility is
0.2-5 mg/litre. The quality and composition of diesel fuel influence
the emissions of pollutants from diesel engines considerably.
Important variables are ignition behaviour (expressed in terms of
cetane number), density, viscosity, and sulfur content. The
specifications of commercial diesel fuel differ considerably in
different countries.
Heating fuels and some kerosene jet fuels produced during the
refining process may have a composition similar to that of diesel
fuel, although with different additives. Biological data on these
mixtures have therefore also been taken into account in the
assessments of toxicity and ecotoxicity.
Owing to the complexity of the diesel fuel mixture, there is no
specific analytical method, and the analytical techniques used in most
environmental assessments are suitable only for measuring the total
petroleum hydrocarbon mixture. The methods consist of preliminary
solvent extraction, a clean-up procedure to remove naturally occurring
hydrocarbons, and subsequent detection by gravimetry, infrared
spectroscopy or gas chromatography. Neither the gravimetric nor the
infrared technique provides useful qualitative or quantitative
information on contaminants and can thus be used only for screening.
Gas chromatography combined with detection techniques such as flame
ionization and mass spectrometry is the standard procedure for
analysing environmental samples. Many other methods are available for
the analysis of individual hydrocarbons in diesel fuels.
A1.2 Sources of human and environmental exposure
Diesel fuels are produced by refining crude oils. In order to
meet technical specifications for performance, diesel fuels are
generally blended; further formulation with additives improves their
properties for specific uses. Diesel fuels are widely used as
transportation fuels. The more volatile fuels, with low viscosity, are
required for high-speed engines and the heavier grades for railroad
and ship diesel engines. Much heavy-duty road transport is powered by
diesel engines. Passenger cars powered by diesel engines are becoming
increasingly more common in Europe and Japan (10-25%), whereas in
North America the percentage of diesel-fuelled passenger cars is about
1-2%, with a slightly decreasing tendency. Diesel fuel is used in
stationary engines and in boilers, e.g. reciprocating engines, gas
turbines, pipeline pumps, gas compressors, steam processing units in
electric power plants, burner installations, and industrial space and
water heating facilities.
Over the last five years, the worldwide demand for diesel fuels
has increased steadily. In 1985, the following amounts of diesel fuel
were consumed: about 170 000 kt per year in North America; about
160 000 kt per year, including gas oils, in the European Union; and
about 46 000 kt per year in Australia, Japan, and New Zealand,
equivalent to a total of 1062 kt per day. In 1990, world demand was
reported to be about 1110 kt per day.
No information is available on emissions during the production of
diesel fuels; however, this source would seem to be of minor
importance, because the refining process is carried out in closed
systems. Emissions may occur principally during storage and
transportation. Diesel fuels are released as a result of spills and at
filling stations during the refuelling of vehicles. The atmosphere and
the hydrosphere are the most heavily affected environmental
compartments. Soil contamination with diesel fuels may occur during
accidents and is also a problem in railroad yards. The numerous
techniques for cleaning soils contaminated with diesel fuel include
excavation, biological methods, and containment.
A1.3 Environmental transport, distribution, and transformation
Very few data are avilable on the environmental fate of diesel
fuels, but the mechanisms of their distribution and transformation are
considered to be comparable to those of heating fuels, such as No. 2
fuel oil, which have been well studied. Spills of diesel fuel on water
spread almost immediately to form a 'slick'. The polar and
low-relative-molecular-mass components dissolve and leach out of the
slick, and the volatile components evaporate from the surface;
microbial degradation also begins. Chemical and biological weathering
alter the composition of the spill. These processes are dependent on
temperature; spills that occur in Arctic conditions are more
persistent than those that occur in temperate climates. In marine
environments, most of the low-relative-molecular-mass aromatic species
are dissolved into the water phase, but the primary branched alkanes,
cycloalkanes, and remaining aromatic compounds may remain in sediments
for more than a year.
Although no information is available on the photooxidation of
diesel fuels in water and air, evaporated oil components are degraded
photochemically. No. 2 fuel oil has been shown to be photooxidized
rapidly in water under environmental conditions.
The individual constituents of diesel fuel are inherently
biodegradable, to varying degrees and at different rates. The
n-alkane, n-alkylaromatic, and simple aromatic molecules in the C10-C22
range are the most readily degradable. Smaller molecules are generally
rapidly metabolized. Long-chain n-alkanes are more slowly degraded,
owing to their hydrophobicity and because they are viscous or solid at
ambient temperatures. Branched alkanes and cycloalkanes are relatively
resistant to biological breakdown, and PAHs are resistant. The overall
rates of degradation of hydrocarbons are limited by temperature, water
content, oxygen, pH, inorganic nutrients, and microbial metabolic
versatility.
Unicellular algae can take up and metabolize both aliphatic and
aromatic hydrocarbons, but the extent to which this actually occurs in
nature is poorly understood. Unlike microorganisms that use petroleum
carbons as a carbon source, animals generally oxidize and conjugate
products, rendering end-products that are more soluble and therefore
easier to excrete. All animal species tested can take up petroleum
hydrocarbons. PAHs, crude oil, and refined petroleum products are
known to induce cytochrome P450 enzymes and to increase the levels of
hydrocarbon metabolism in numerous marine and freshwater fish species.
Few data are available on the bioaccumulation of diesel fuel in
the laboratory, but there is plentiful evidence from studies of spills
and laboratory studies on other oils, particularly No. 2 fuel oil,
that aquatic organisms bioconcentrate hydrocarbons. The
n-octanol-water partition coefficient for diesel fuel is 3.3-7.06,
which suggests high potential bioaccumulation; however, many of the
lower-relative-molecular-mass compounds are readily metabolized, and
the actual bioaccumulation of higher-relative-molecular-mass compounds
is limited by their low water solubility and large molecular size.
Thus, actual bioaccumulation may be low.
Fish have been tainted by diesel fuel after spills. No data are
available on the biomagnification of diesel fuel.
No experimental data are available on the movement of diesel fuel
through the soil, although a direct correlation between the movement
and kinematic viscosity has been proposed. The movement of kerosene
through soil depends on the moisture content and nature of the soil.
A1.4 Environmental levels and human exposure
As diesel fuels are complex mixtures, the environmental levels
have not been measured. The individual constituents of diesel fuels
can be detected in almost all compartments of the environment,
although their source cannot be verified. The general population may
be exposed to diesel fuel at filling stations and as a result of
spills.
Occupational exposure to diesel fuel occurs in a large number of
activities. Because of their low volatility, diesel fuels should
generate only low concentrations of vapours at normal temperatures,
but high operating temperatures can result in significant
concentrations.
A1.5 Effects on laboratory mammals and in-vitro test systems
The acute toxicity of diesel fuels is low after oral or dermal
exposure or after inhalation. The oral LD50 value was > 5000 mg/kg
body weight in all species tested (mouse, rabbit, rat, guinea-pig).
Dermal application resulted in an LD50 value of > 5000 mg/kg body
weight in mice and rabbits, although values of > 2000 mg/kg body
weight were reported for some kerosenes and middle distillates, with
different protocols and lower limit doses. The LC0 value in rats
exposed by inhalation was about 5 mg/litre, except for one
straight-run middle distillate for which a value of 1.8 mg/litre was
seen.
In rabbits treated dermally with up to 8000 µl/kg body weight per
day and mice with up to 40 000 mg/kg body weight per day, acanthosis
and hyperkeratosis due to severe irritation were seen. Rabbits were
more sensitive than mice. Inhalation of diesel fuel was neuro-
depressive in mice at concentrations up to 0.2 mg/litre but not
in rats exposed to up to 6 mg/litre. Body and liver weights were
reduced in rats.
Mice, rats, and dogs did not show significant cumulative toxicity
after inhalation of up to 1.5 mg/litre subchronically. The specific
nephropathy syndrome seen in male rats is linked to an inherent
accumulation of hyalin droplets in the renal tubules.
The only effects of long-term exposures were ulceration after
dermal application to mice (250 or 500 mg/kg body weight per day) and
significant alterations in organ weight after inhalation of 1 or
5 mg/litre by rats. In both studies the mean body weights were
reduced.
Various types of diesel fuels were slightly to severely
irritating to the skin of rabbits. Diesel fuels do not irritate the
eye, but some kerosenes have been reported to have a slight irritating
effect. Diesel fuels do not cause skin sensitization.
Diesel and jet fuels (kerosene) were neither embryotoxic nor
teratogenic in two studies in rats exposed by inhalation to 100 or
400 ppm and in one study in which rats were given up to 2000 mg/kg
body weight per day by gavage. In the last study, reduced fetal weight
was observed.
Tests in Salmonella typhimurium did not provide clear evidence
of mutagenicity. Some positive findings in S. typhimurium and in
mouse lymphoma cells were considered to be equivocal owing to the
inconsistency of the results. Tests for genotoxicity in mice in vivo
(induction of micronuclei or chromosomal aberrations) also gave
equivocal or negative responses.
Diesel fuels induced a low level of dermal carcinogenicity. In
the present state of research, it cannot be concluded whether the
carcinogenic potency of diesel fuels is mediated by a genotoxic
mechanism or by chronic dermal damage.
A1.6 Effects on humans
Non-occupational exposure to diesel fuel can occur during manual
filling of fuel tanks. The primary source of dermal exposure is
accidental spills, which result in immediate high levels of exposure
but are of short duration.
After accidental dermal contact, anuria, renal failure, gastro-
intestinal symptoms, and cutaneous hyperkeratosis have been reported.
Toxic lung disease has been observed after accidental ingestion of
diesel fuel and subsequent aspiration. Persistent productive cough has
been reported after inhalation. In a case-control study of men exposed
to diesel fuel, an increased risk for cancer of the lung other than
adenocarcinoma was found; a positive association was also seen with
prostatic cancer, although a higher risk was noted for the group with
'nonsubstantial' exposure than for that with 'substantial' exposure.
In a cross-sectional study of factory workers exposed to kerosene jet
fuels, dizziness, headache, nausea, palpitation, pressure in the
chest, and eye irritation were found to be more prevalent than in
unexposed controls. The time-weighted average concentration of
vapour from the fuel in the breathing zone was estimated to be
128-423 mg/m3.
A1.7 Effects on other organisms in the laboratory and the field
Diesel fuel is more toxic than crude oil to aquatic organisms and
plants. The ecotoxicity of diesel fuel is generally attributed to
soluble aromatic compounds, but insoluble aliphatic hydrocarbons may
also be implicated. Of the aromatic compounds, monoaromatics are the
least toxic, their acute toxicity increasing with molecular mass up to
the four- to five-ring compounds, although these are poorly soluble in
seawater. In some animals, e.g. fish and birds, physical coating of
the body surface by the fuel can produce toxicity and mortality.
Laboratory experiments have been carried out on diesel fuel,
water-soluble fractions, oil-water dispersions, and microencapsulated
oil. Diesel fuel did not significantly reduce the growth in culture of
the green alga Euglena gracilis, whereas a low concentration (0.1%)
almost completely inhibited the growth of Scenedesmus quadricauda.
Light diesel fuel (0.05%) stimulated the growth, photosynthesis, and
chlorophyll asynthesis of Chlorella salina but slightly inhibited
respiration; at higher concentrations, the growth rate and
photosynthesis were greatly reduced. Long-term exposure inhibited the
growth of the benthic algae Ascophyllum nodosum and Laminaria
digitata. In blue-green algae, photosynthesis was reduced by the
aromatic and asphaltic fractions but not by the aliphatic fraction.
Diesel fuel was acutely toxic to Daphnia spp., chironomid
larvae, and the mollusc Viviparus bengalensis (Gastropoda). A
concentration of 0.1 ml/litre caused the death of tidepool copepods,
Tigriopus californicus, within five days.
Mytilus edulismussels accumulate diesel fuel, have markedly
reduced feeding and growth rates, and show reproductive toxicity after
chronic exposure to diesel fuel. The EC50 for spawning in mussels
exposed for 30 days was about 800 µg/litre. The LC50 of micro-
encapsulated diesel oil after exposure of maturing mussels for
30 days was about 5000 µg/litre. Diesel oil was more toxic to larvae
than to juveniles: 10 µg/litre had adverse effects on the growth of
larvae.
Freshwater crabs (Barytelphusa cunicularis) exposed to sublethal
concentrations of diesel fuel for up to 96 h generally reduced their
oxygen consumption, particularly at lower exposures up to 8 h. With
longer exposures, the oxygen consumption was equal to or higher than
that of the controls.
In 96-h tests of acute toxicity in juvenile salmonids under
static conditions, diesel fuel was more toxic to pink salmon,
Onchorhychus gorbuscha (LC50: 32-123 mg/litre), than to cohosalmon,
O. kisutch (LC50: 2186-3017 mg/litre), or rainbow trout,
O. mykiss (LC50: 3333-33 216 mg/litre), irrespective of water type.
The threshold for detection of behavioural responses of cod
( Gadus morhua L.) exposed to diesel fuel in seawater was within
100-400 ng/litre. The Antarctic fish Pagothenia borchgrevinki
withstood an undiluted water-soluble fraction of diesel fuel oil for
up to 72 h but showed signs of stress.
Birds are affected externally and internally by oil
contamination. Diesel fuel destroys the waterproof nature of the
birds' plumage and is ingested during preening. Diesel and fuel oil
fed by gavage at 2 ml/kg body weight to ducks caused lipid pneumonia,
extreme inflammation of the lungs, fatty infiltration of the liver,
and hepatic degeneration after 24 h. Administration of diesel or fuel
oil at 1 ml/kg caused severe irritation of the digestive tract and
toxic nephrosis. Higher doses resulted in adrenal enlargement (mainly
due to hyperplasia of cortical tissue), depression of plasma
cholinesterase levels, ataxia, and tremors. Doses up to 20 ml/kg body
weight were not fatal to healthy birds, but the LD50 for diesel and
fuel oil administered to birds under stress was 3-4 ml/kg body weight.
After spills of diesel fuel, zooplankton appear to be highly
vulnerable to dispersed and dissolved petroleum constituents but less
so to floating oils. Aquatic organisms may be affected in a number of
ways, including direct mortality (fish eggs, copepods, and mixed
plankton), external contamination by oil (chorions of fish eggs and
cuticles and feeding appendages of crustaceans), tissue contamination
by aromatic constituents, abnormal development of fish embryos, and
altered metabolic rates.
A1.8 Evaluation of human health risks
The general population can be exposed to diesel fuel and other
middle distillates at filling stations, as a result of accidental
spills, during the handling of such fuels, and during use of kerosene
for domestic cooking or heating. Workers can be exposed to diesel fuel
and other middle distillates while handling and discharging the fuel
at terminals, storage tanks, and filling stations; during the
manufacture, repair, maintenance, and testing of diesel engines and
other equipment; during use of diesel fuel as a cleaning agent or
solvent; and in handling and routine sampling of diesel fuel in the
laboratory. Owing to the low volatility of diesel fuel, only low
concentrations of vapour are likely to occur at room temperature,
although in confined spaces at high temperatures significant levels
may be found.
Exposure to vapour is minimal during the normal handling of
diesel fuel. The most likely effect on human health is dermatitis
after skin contact. Diesel fuel is a skin irritant but does not appear
to irritate the eye. Acute toxic effects on the kidney can occur after
dermal exposure, but the effects of long-term dermal absorption of low
concentrations are unknown.
Diesel fuels are toxic when ingested, sometimes resulting in
regurgitation and aspiration, which can cause chemical pneumonia; the
same is true for any hydrocarbon in a particular range of viscosity.
In rodents exposed by inhalation to diesel fuel at concentrations
up to 0.2 mg/litre, a neurodepressive effect was seen in mice but not
in rats at the higher concentrations. Subchronic exposure by
inhalation to various distillate fuels induced specific
alpha2-microglobulin nephropathy in male rats; this effect is
considered irrelevant for humans.
Diesel fuels were neither embryotoxic nor teratogenic in animals
exposed orally or by inhalation.
There is no clear evidence of mutagenic activity in bacteria, and
the results of other tests for genotoxicity in vitro and in vivo were
equivocal.
A case-control study of workers exposed to diesel fuel suggested
an increased risk for cancer of the lung other than adenocarcinoma and
for prostatic cancer. In neither case was there an exposure-response
relationship. In view of the small number of studies available, the
small number of cases, and the correspondingly wide confidence
intervals, no conclusion can be drawn about the carcinogenicity to
humans of diesel fuel.
In mice, dermally administered diesel fuels had weak carcinogenic
potential. In view of the absence of clear genotoxicity, cancer could
be induced by nongenotoxic mechanisms, e.g. by chronic dermal
irritation characterized by repeated cycles of skin lesions, causing
epidermal hyperplasia.
A1.9 Evaluation of effects on the environment
The environment can be polluted by accidental release of diesel
fuel on a large scale, such as during tanker disasters and pipeline
leaks, or on a smaller scale from contamination of soil around
factories or garages. In water, diesel fuel spreads almost
immediately, polar and low-relative-molecular-mass components dissolve
and leach out, volatile components evaporate from the water surface,
and microbial degradation begins. The extent to which 'weathering'
takes place depends on the temperature and on climatic conditions. The
chemical composition of spills changes with time: after spillage on
water, some fractions evaporate, and the evaporated diesel components
are degraded photochemically; in sediment, diesel fuel appears
generally to be delivered to bottom sediments by settling particles;
in soil, the components of diesel fuel migrate at different rates,
depending on the soil type.
The individual constituents of diesel fuel are inherently
biodegradable, but the rates of biodegradation depend heavily on
physical and climatic conditions and on microbial composition.
Aquatic organisms, in particular molluscs, bioaccumulate
hydro-carbons to varying extents, but the hydrocarbons are depurated
on transfer to clean water. Diesel fuel may be bioaccumulated; no data
are available about biomagnification.
Spills of diesel fuel have an immediate detrimental effect on the
environment, causing substantial mortality of biota. Recolonization
may occur after about one year, depending on the animal or plant
species and the chemical and physical content of the spill residues.
Aquatic organisms that survive diesel fuel spills can be affected by
external oil contamination and tissue accumulation: abnormal
development and altered metabolic rates are signs of the resulting
stress.
A2. IDENTITY, PHYSICAL AND CHEMICAL PROPERTIES, AND ANALYTICAL
METHODS
A2.1 Identity
Diesel fuels are a gas-oil fraction occurring during petroleum
separation and commonly known as middle distillates (International
Agency for Research on Cancer, 1989a). Gas oils are generally blended
materials formulated to meet technical specifications (CONCAWE, in
press). Commercial diesel fuels contain aliphatic, olefinic,
cycloparaffinic, and aromatic hydrocarbons (see section A2.1.1), and
additives (see section A2.1.2) to improve their fuelling properties
(Sandmeyer, 1981).
Four qualities of diesel fuel are available commercially: diesel
fuel (general), diesel fuel No. 1, diesel fuel No. 2, and diesel fuel
No. 4 (see Table 1). The composition of diesel fuels is comparable to
that of heating oils (e.g. No. 1 and No. 2 fuel oils), except for the
additives (International Agency for Research on Cancer, 1989a; Agency
for Toxic Substances and Disease Registry, 1995).
Diesel fuel No. 2 is used mainly as automobile fuel and
corresponds to diesel fuel (general). In Europe (countries of the
European Union (EU) and European Free Trade Area (EFTA)), the
specifications for diesel fuel for transportation purposes are given
in European standard EN 590 (European Committee for Standardization,
1993), which also provides for changes in the specifications to meet
the requirements of different climatic conditions. In Sweden, two
further qualities of on-road diesel fuel are available: environmental
class 1 and class 2 (city diesel), with sulfur contents of 0.05% and
0.001%, respectively (Standardization Board in Sweden, 1991). The
sulfur content of city diesel corresponds to that of kerosene. Diesel
fuel for ship engines is covered by the International Standards
Organization (ISO) standard 8217 (International Standards
Organization, 1987). In the United States of America, three grades of
diesel fuel are available: diesel fuel No. 1 (relatively high
volatility) for road vehicle engines subject to frequent speed and
load changes; diesel fuel No. 2 (lower volatility) for industrial or
heavy-duty, high-load engines running at uniform speed; and diesel
fuel No. 4 (viscous) for low- and medium-speed engines such as those
used in ships (American Society for Testing and Materials, 1988,
1992).
Several types of kerosene, also derived from the gas-oil fraction
of petroleum separation, are used as aviation turbine fuels (JP fuels,
jet fuels). Their hydrocarbon composition is comparable to that of
diesel fuels.
A2.1.1 Fuel components
A2.1.1.1 Alkanes
Normal, branched, and cyclic alkanes (paraffins) are the most
abundant components (about 65-85%) of diesel fuels. Pristane
(2,6,10,14-tetramethylpentadecane) and phytane (2,6,10,14-
tetramethyl-hexadecane) are of particular interest environmentally, as
the ratios of pristane to heptadecane and of phytane to octadecane
make it possible to identify the source of a fuel spill; furthermore,
as these ratios increase during biological degradation, they can be
used to estimate the age of an environmental contamination and the
degree of elimination. Cycloalkanes and bicycloalkanes constitute a
significant portion of the mixture, but individual compounds are
present only at low levels and are difficult to analyse. Alkyl
derivatives of cyclopentane, cyclohexane, and cycloheptane are common
components (Block et al., 1991; Table 2).
A2.1.1.2 Alkenes
Alkenes are not common components of crude oil but may be
present in diesel fuel if converted products are added after cracking.
These alkenes have predominantly branched and cyclic structures (Block
et al., 1991). The total alkene content of diesel fuels is up to 10%
(CONCAWE, 1985) (see also Table 2).
A2.1.1.3 Aromatic compounds
Aromatic compounds constitute 5-30% of automotive diesel fuel,
5-40% of marine diesel fuel (CONCAWE, 1985), and 10-30% of diesel
fuel No. 2 (Block et al., 1991). Table 2 shows the specifications of
commercial diesel fuels in this regard.
Table 1. Synonyms and trade names of commercial diesel fuels
Name CAS CAS Registry Range of Synonyms
name number carbon
numbers
Diesel fuel Diesel oil 68334-30-5 C9-C20a Auto diesel, automotive
(general) C10-C28b diesel oil, DERV, diesel,
diesel fuel oil, diesel
oil, gas oil
Diesel fuel Not assigned C9-C16c Diesel fuel oil No. 1,
No. 1 (essentially C4-C16 (for diesel oil No. 1, No. 1
equivalent to wide-cut dieseld
kerosene, aviation)c
8008-20-6)
Diesel fuel No. 2 68476-34-6 Diesel fuel, diesel fuel
No. 2 diesel (applicable for oil No. 2, diesel oil
fuel specific No. 2, No. 2 diesele
viscosity
limits)
Diesel fuel 68476-31-3 C10-C30f Marine diesel fuel,
No. 4 distillate marine diesel
fuel
Adapted from International Agency for Research on Cancer (1989a) and supplemented
a From CONCAWE (in press)
b From CONCAWE (1985); automotive gas oil (automotive diesel fuel, DERV)
c From CONCAWE (1985, 1995)
d In Europe, fuels similar to US diesel No. 1 are commonly referred to as
'kerosene' or 'Arctic diesel'
e Term uncommon in Europe. In the United Kingdom, distillate fuels are frequently
categorized as Class A1 (road diesel) and A2 (off-highway diesel)
f From CONCAWE (1985); distillate marine diesel
Only trace quantities of toxicologically relevant benzene,
toluene, ethyl benzene, and xylene compounds (for physicochemical
properties, see Table 6) are present in diesel fuel No. 2, but
significant levels are found in diesel fuel No. 1 (Arctic diesel),
which has lower flash-point specifications (Block et al., 1991); the
International Agency for Research on Cancer (1989a) cites a
flash-point of 0.25-0.5%. The concentration of benzene in kerosenes is
< 0.01% by volume; wide-cut aviation kerosenes may have higher
levels, but they are usually < 1% by volume (IPCS, 1986; CONCAWE,
1995; IPCS, 1993).
Table 2. Hydrocarbon specifications of some commercial diesel fuel oils
Specification Diesel Keroseneb Distillate Diesel
fuela marine fueld
dieselc
Paraffins/naphthenes 65-95e 78-96 60-90
(volume %) (wide-cut
aviation, < 1)
n-Hexane (volume %) < 0.01
(wide-cut
aviation, < 1)
Saturates (volume %) 59.4-76.6
Olefins (volume %) 0-10 0-5 0-10 0.0-1.0
Aromatics (volume %) 5-30 4-25 5-40 23.4-39.6
(wide-cut
aviation,
6-25)
Aromaticity (weight %) 11-15
See also Table 1
a From CONCAWE (1985, in press); fuel oil similar to diesel fuel (general)
b From CONCAWE (1985, 1995); fuel oil similar to diesel fuel No. 1
c From CONCAWE (1985, in press); fuel oil similar to diesel fuel No. 4
d From German Scientific Association for Petroleum, Natural Gas, and Coal (1991);
three samples of diesel fuel (general)
e Depending on origin of crude oil
Alkyl benzenes (particularly C3 and C4) are common components of
diesel fuel. Polycyclic aromatic hydrocarbons (PAHs), e.g.
naphthalene, phenanthrene, acenaphthene, acenaphthylene, fluorene,
fluoranthene, and pyrene, are also present, as are alkyl- and
cycloalkyl-substituted homologues of these substances, the predominant
ones being naphthalene and its methyl-substituted derivatives (see
Table 6 for physicochemical properties) (Block et al., 1991).
As some PAHs and the benzene, toluene, ethyl benzene, and xylene
components have been shown to be toxic and ecotoxic, these classes of
compounds are usually included in analytical procedures for
environmental contamination by diesel fuel. The PAH content of diesel
fuels varies widely, the highest levels being found in low-quality
fuel blended for large users (frequently railroad companies). The
mid-range aromatic (and PAH) content of diesel blends is limited by
the cetane number specification (Block et al., 1991) (see section
A2.1.3).
The concentrations of total PAHs in diesel fuel are < 5% by
volume, although some marine diesel fuels may contain > 10% by volume
(CONCAWE, 1985; International Agency for Research on Cancer, 1989a).
In straight-run gas-oil components, which are the major blending
material of diesel fuel (see section A3.2.1.1), three-ring PAHs
predominate; use of heavier atmospheric vacuum or cracker gas oils in
a diesel-fuel mixture leads to an increasing content of four- to
six-ring PAHs (CONCAWE, in press).
The concentrations of these constituents in a commercial diesel
fuel (unspecified) and, for comparison, in No. 2 fuel oil are shown in
Table 3. It should be noted that the PAH content of No. 2 fuel oil is
not limited by cetane number specification, so that it may include a
larger proportion of these hydrocarbons (Block et al., 1991). Table 3
also gives the composition of the water-soluble fractions of diesel
and No. 2 fuel oils and indicates how the solubility of a compound
affects the composition of the fraction and of the whole oil.
A2.1.1.4 Sulfur
The sulfur content of middle distillates depends on the source of
crude oil (Booth & Reglitzky, 1991; CONCAWE, 1995). The sulfur content
of most diesel fuels is 0.1-0.5% by weight; it is higher than that of
gasoline, which is about 0.02% by weight (Scheepers & Bos, 1992a).
Only diesel fuel No. 4 (distillate marine diesel) has a sulfur level
> 1% by weight (CONCAWE, 1985, in press). ISO standard 8217
(International Standards Organization, 1987) specifies a sulfur
content of marine diesel fuel of 1.0-2.0% by weight.
The sulfur content of some diesel fuels ranges from 0.01 to > 3%
by weight. In Europe (countries of EU and EFTA), the sulfur content is
restricted to a maximum of 0.2-0.3% by weight, and, as of 1996, it
will be further reduced to 0.05% by weight (European Commission,
1993). In the United States in 1988, the maximal sulfur content
permitted was 0.5% by weight for diesel fuels No. 1 and 2 and 2.0% by
weight for diesel fuel No. 4 (American Society for Testing and
Table 3. Concentrations of toxicologically relevant aromatic hydrocarbons in diesel fuel and No. 2 fuel oil and in 10% water-soluble
fractions prepared from them
Compound Diesel fuela Diesel fuelb No. 2 fuelc No. 2 fueld Water-soluble fractions (µg/litre)
(% by wt) (% by wt) (% by wt) (% by wt)
No. 2 Diesel
fueld fuela
Benzene 0.1 > 0.02 0.006-0.008 NR 550 344
Toluene 0.7 0.25-0.5 0.01-0.08 NR 1040 777
Alkylbenzenese 970
Ethylbenzene 0.2 0.25-0.5 0.01-0.08 NR 139
Xylene 0.5 0.25-0.5 0.01-0.08 NR 875
Polycyclic aromatic hydrocarbons
Naphthalene 0.4 0.273 0.4 840 6.6
1-Methylnaphthalene NR NR 0.82 340 66.2
2-Methylnaphthalene NR 0.67 1.89 480 108
Dimethylnaphalenese NR NR 3.11 240 NR
Trimethylnaphthalenese NR NR 1.84 30 NR
Fluorenese NR NR 0.36 20 NR
Phenanthrenese NR 0.15 0.53 20 NR
NR, not reported
a From Dunlap & Beckmann (1988); the analytical method is not described in detail; the concentration of benzene seems to be
unusually high.
b From International Agency for Research on Cancer (1989a); according to CONCAWE (1985), some marine diesel fuels may contain
more than 10% polycyclic aromatic hydrocarbons.
c From Stone (1991); summary of several reports
d From Anderson et al. (1974); US National Research Council (1985)
e Total of several isomers
Materials, 1988); in October 1993, the maximum was reduced to 0.05% by
weight (US Environmental Protection Agency, 1992a; American Society
for Testing and Materials, 1992). The permitted sulfur level in Brazil
is > 3% by weight (A. Sivak, personal communication, 1993). In Japan,
the sulfur content of diesel fuels was reduced to 0.2% by weight in
1994, and a further reduction, to 0.05% by weight, is under discussion
(CONCAWE, 1990a). Blended marine diesel fuel may also contain up to
about 15% residual components, i.e. material with an initial
boiling-point above about 350°C (CONCAWE, in press).
A2.1.2 Fuel additives
Only agents that are added to fuels at a concentration < 1% are
described as 'additives'. A more appropriate term for substances
present at higher concentrations is 'fuel components'. Fuels are
treated with additives for a number of reasons (see Table 4 and
below); they also differentiate products and determine the trademark
quality of commercial fuels (Fabri et al., 1990).
A2.1.2.1 Cetane number improvers
Cetane number improvers upgrade the ignition characteristics of a
base fuel more economically than refinery processes (Fabri et al.,
1990) (see section A2.1.3). Primary alkyl nitrates (e.g. isooctyl
nitrate) are often used to improve cetane number. Polyethyleneglycol
dinitrates, although effective at much lower concentrations, have a
number of disadvantages, including their price and the fact that they
may not improve the performance of fuel in low-compression engines
(Russell, 1989).
A2.1.2.2 Smoke suppressors
Organometallic compounds containing barium, calcium, manganese,
or iron have been used to reduce diesel smoke. With barium-based
products, 85-95% of the metal is emitted as particulates in the
exhaust (Russell, 1989); however, barium and calcium compounds are no
longer used.
A2.1.2.3 Flow improvers
Cold-flow improvers increase the fluidity of the fuel by
modifying the growth of wax crystals formed by higher homologues of
paraffins at low temperatures. The wax content of diesel fuels is
influenced by the origin of the crude oil, the distillation range of
the fuel, and the source of blend components (Coley, 1989).
Table 4. Diesel fuel additives
Additive Material Concentration Effect
(ppm)
Ignition improvers, Organic nitratesa Enhancement of self-ignition qualitiesa
cetane enhancersa
Smoke suppressors, Organic compounds of Ca, Ba, Reduction of soot; increase in metal
combustion enhancersa or (sometimes)Mga sulfate emissionsa
Detergentsa Amines, imidazolines, Prevention and removal of coke deposits
succinimides, etc.b on fuel injector tips, etc.a
Flow improvers Olefin-ester copolymers 50-500 Interaction with wax crystals and
modification of their growth; prevention
of formation of agglomerates
Cloud-point depressors Olefin-ester copolymers About 1000 Depression of cloud-point; prevention of
formation of agglomerates
Wax anti-settlers Modified ethylene-vinyl 100-500c Reduction of crystal size and rate of
acetate copolymersc settling; prevention of formation of agglomerates
Anti-static agents Not reported Not reported Reduction of building up of charges of
static electricity
Anti-corrosion chemicals Alkenyl succinic acids and 5-50 Prevention of corrosion or rusting of
esters, dimer acids, amine storage tanks, pipelines, and metal fuel
salts system components
Table 4 (contd)
Additive Material Concentration Effect
(ppm)
Antioxidants Hindered phenols or amines 25-200 Prevention of aging processes
Anti-foam agents Silicones Up to 20 Reduction of foaming tendency; reduction
of risk of ground pollution from oil spills
Dehazers Quaternary amine salts 5-50 Reduction of formation of hazes;
acceleration of haze clearance
Biocides Imines, amines, About 200 Prevention of growth of bacteria and
imidazolines, etc. fungi in storage tank bottoms
Lubricants Surface-active agents such 50-500 Compensation of lower viscosity of fuels
as polyfunctional acids and in low-temperature regions
derivatives
Odour maskers Natural, identical substances, 10-100 Reduction or elimination of smell
such as vanillin and terpenesc
From Coley (1989), except as noted
a From Organisation for Economic Co-operation and Development (1993)
b From Russell (1989)
c From Fabri et al. (1990)
A2.1.2.4 Cloud-point depressors
Diesel fuels must be easily filterable, as wax crystals formed at
low temperatures can clog fuel filters. Cloud-point depressors are
therefore added (Fabri et al., 1990) which consist of substances with
lower cloud-points, e.g. kerosene. Addition of 10% kerosene lowers the
cloud-point of diesel fuel by about 2°C. Olefin-ester copolymers
depress the cloud-point by 3-4°C but are not currently in commercial
use (Coley, 1989).
A2.1.2.5 Wax anti-settling additives
These additives inhibit the tendency of wax to settle by reducing
the crystal size and slowing the settling rate. A five-fold reduction
in wax crystal size slows the settling rate by one-twenty-fifth. With
increasing temperature, small dispersed crystals redissolve more
readily than settled wax (Coley, 1989).
A2.1.2.6 Other additives
Detergents, including amines, amides, imidazolines, and
succinates, are used to reduce injector nozzle fouling. Detergents
such as polyalkenyl succinimides also improve fuel stability,
resistance to corrosion, and combustion efficiency (Russell, 1989).
Antistatic agents lower the risk of building up a charge of static
electricity during pumping at high rates at bulk terminals or in
large-capacity truck fuel tanks.
Other additives used are anti-oxidants (phenols, amines),
anti-corrosion chemicals (alkenyl succinic acids, esters, dimer acids,
amine salts), anti-foam agents (silicones), dehazers (anti-emulsion
agents) (quaternary ammonium salts), biocides, lubricants for cold
regions (surface-active polyfunctional acid derivatives), and odour
maskers (vanillin, terpenes) (Coley, 1989; Fabri et al., 1990).
A2.1.3 Quality of diesel fuels
A2.1.3.1 Ignition performance and cetane number
The cetane number determines the ignition performance of
transport fuels relative to a scale on which methyl naphthalene
corresponds to a combustion rate of 0 and cetane to one of 100
(Scheepers & Bos, 1992a). The cetane number is calculated by comparing
the ignition quality of a fuel with that of two reference fuel blends
of known cetane numbers under standard operating conditions (American
Society for Testing and Materials method D 613 CFR). A high cetane
number improves cold starting and engine durability and reduces noise,
fuel consumption, smoke emissions during warm-up, and exhaust
emissions (Russell, 1989). In Europe (countries of the EU and EFTA),
the minimal cetane number must be in the range 45-49, depending on the
climatic conditions (European Committee for Standardization, 1993);
cetane numbers are usually 49-53 (CONCAWE, 1987). In the United
States, the cetane number must be at least 30 for diesel fuel No. 4
and 40 for diesel fuels No. 1 and 2 (American Society for Testing and
Materials, 1988, 1992).
A2.1.3.2 Density
The density of diesel fuel influences engine performance: higher
density leads to enrichment of the fuel:air mixture, which results in
greater engine power output. Enrichment may, however, increase the
particulate content of exhaust gas emissions (Fabri et al., 1990) (see
section B3.1.2.2). A density range is specified in fuel standards in
some countries (American Society for Testing and Materials, 1992;
European Committee for Standardization, 1993).
A2.1.3.3 Sulfur content
Gas and particle emissions in diesel engine exhaust are
influenced by the sulfur content of the fuel; there is a direct
relationship between particle production and sulfur content (Hare,
1986) (see section B3.1.2.2).
A2.1.3.4 Viscosity
Too low a viscosity can lead to wear in the injection pump; too
high a viscosity impairs fuel injection and mixture formation (Fabri
et al., 1990). In Europe (countries of the EU and EFTA), the viscosity
of commercial diesel fuels at a temperature of 40°C must be
1.5-4.5 mm2/s (European Committee for Standardization, 1993). In the
United States, the permitted ranges of viscosity at 40°C are
1.3-2.4 mm2/s for diesel fuel No. 1, 1.9-4.1 mm2/s for diesel fuel
No. 2, and 5.5-45.0 mm2/s for diesel fuel No. 4 (American Society
for Testing and Materials, 1988, 1992).
A2.1.3.5 Cold-flow properties
Cloud-point and cold filter plugging point characterize the
behaviour of diesel fuels at low temperatures (Fabri et al., 1990).
These points are lowered by the addition of cloud-point depressors and
by special blending techniques, e.g. increasing the kerosene content
of the fuel (see section A2.1.2).
Changes in diesel fuel quality have been assessed. Wade & Jones
(1984) reported a deterioration in fuel quality with decreasing cetane
number and found that a 90% increase in boiling-point led to greater
emissions of particulates, nitrogen oxides and PAHs. A decline in
diesel fuel quality on the European market was predicted, as the
rising demand would lead to greater use of fuels from catalytic or
thermal cracking processes (CONCAWE, 1987) (see section A3.2.1.1). A
study by the Organisation for Economic Co-operation and Development
(1993) indicated an improvement in the quality of diesel fuel in the
United States due to a decline in aromaticity.
A2.2 Physical and chemical properties
Diesel fuel is a brown, slightly viscous, flammable liquid at
room temperature (Sandmeyer, 1981). It generally has a kerosene-like
odour (Agency for Toxic Substances and Disease Registry, 1995). Its
physical and chemical properties are listed in Table 5.
The water solubility of diesel fuels varies. The aqueous
solubility of crude and fuel oils in the environment is clearly
dependent on the salinity of the water and the age of the oil slick
(see section A4.1.1) and is of the same order of magnitude as the
solubility of fuel oils: at room temperature, 0.37-0.53 mg/litre in
sea water (Boehm & Quinn, 1974) and 0.7-11 mg/litre in tap water
(Lysyj & Russell, 1974). The solubility of a fuel slick decreases with
its age as the concentration of long-chain hydrocarbons increases; the
solubility of fresh crude oil is 29.3-32.3 mg/litre, whereas that of
weathered crude oil is 0.06-23.2 mg/litre at 25°C (Mackay & Shiu,
1976).
The physicochemical properties of the toxicologically relevant
benzene, toluene, ethyl benzene, xylene and PAH components are given
in Table 6.
A2.3 Analytical methods
Exhaustive identification and quantification of the individual
constituents of commercial diesel fuel (see section A2.1) is almost
impossible owing to their number and complexity. In most environmental
assessments, therefore, the mixture is analysed as total petroleum
hydrocarbon (Block et al., 1991). All such methods involve preliminary
solvent extraction of the matrix, with e.g. trichlorotrifluoroethane.
This step may also extract naturally occurring hydrocarbons, which
interfere with the analysis; however, some of these compounds are
polar and can be removed on silica gel. Three analytical methods are
available:
Table 5. Physicochemical properties of diesel fuels
Property Diesel fuel Diesel fuel Diesel fuel Diesel fuel
(general) No. 1 No. 2 No. 4
Melting-point (°C) - 34a 18a - 29-9a
Boiling range (°C) 160-190b 145-300 (wide-cut 282-338a 170-420d
143-384e aviation, 45-280)c 101- > 588a
193-293a
Flash-point (°C) > 56b > 21 - < 55 52 (closed cup)a > 56d
58-66e (wide-cut aviation, > 54 (closed cup)a
(Pensky-Martens) < 21)c
38 (closed cup)a
Autoignition temperature (°C) 177-329a 254-285a 263a
Density (g/cm3) 0.81-0.90 (15°C)b 0.805 (wide-cut 0.87-0.95 0.87-0.92 (15°C)d
0.82-0.84 (15°C)e aviation, 0.75-0.801) (20°C) 0.81-0.94 (15°C)
(15°C)c 0.81-0.94 1 (20°C)
(15°C)
Kinematic viscosity (mm2/s) 2-7.4 (40°C)b 1.5-2.5 (wide-cut 2-7.4 (40°C)d
2.20-3.25 (40°C)e aviation, about 1.1
(20°C)c
Vapour pressure (kPa) About 40 (40°C)b About 10 (wide-cut 2.83-35.2 2.83-35.2 (21°C)a
0.04f aviation, 140-210) (21°C)a
(Reid, 37.8°C)c
2.83-35.2 (21°C)a
Table 5 (contd)
Prpoerty Diesel fuel Diesel fuel Diesel fuel Diesel fuel
(general) No. 1 No. 2 No. 4
Water solubility (mg/litre) 1f About 5 (20°C)a About 5 (20°C)a About 5 (20°C)a
0.2f
Henry's law constant 4.3 × 103f 6.03-7.5 × 105a 6.03-7.5 × 105a 6.03-7.5 × 105a
(Pa × m3/mol) (20°C)
n-Octanol-water partition 3.3-7.06a 3.3-7.06a 3.3-7.06a
coefficient (log Kow)
Soil sorption coefficient 3.04f 3.0-6.7a 3.0-6.7a 3.0-6.7a
(log Koc)
Diffusion coefficient in air 4.63 × 10-2f
(cm2/s)
Odour threshold (ppm) 0.7a 0.5g
a From Agency for Toxic Substances and Disease Registry (1995)
b From CONCAWE (in press); automotive gas oil
c From CONCAWE (1985, 1995); kerosenes
d From CONCAWE (in press); distillate marine diesel
e From German Scientific Association for Petroleum, Natural Gas, and Coal (1991); average of three samples
f From Custance et al. (1993); water solubility measured, other data from literature; no further details
g From Fraser Williams (Scientific Systems) Ltd (1985)
-- Gravimetric detection: determination of the weight of residue
remaining after solvent evaporation. Although this method is
useful for measuring gross contamination, it cannot be used in
trace analysis.
-- Infrared detection: the absorbance of petroleum hydrocarbons is
detected in a solvent matrix at the maximal value, near
2930 cm-1. This carbon-hydrogen bond stretching absorbance is
directly related to the hydrocarbon concentration in the extract.
The results are dependent on the hydrocarbon standard used for
quantification.
-- Gas chromatographic detection: capillary gas chromatography
combined with flame ionization or mass spectrometric detection.
The gravimetric and infrared techniques are fast, relatively
simple and widely accepted by regulatory authorities; however, they do
not provide sufficient qualitative and quantitative information on
composition. Gas chromatography is therefore the standard procedure
used to identify and quantify fuel constituents in environmental
samples. Different distribution and degradation processes in
environmental compartments (see section A4) mean that the composition
of petroleum hydrocarbons in air, water, soil, and biota may differ
considerably from that of the original fuel. Newton et al. (1991)
developed an analytical method for identifying and quantifying traces
of diesel contamination in tinned fish products on the basis of the
n-alkane pattern.
Because of the suspected toxicity of aromatic components in
diesel fuel, a detailed analysis is often necessary. Two groups of
compounds are detected:
-- volatile aromatic compounds: Analysis of these minor components
of diesel fuel requires special enrichment techniques, such as
purge-trap gas chromatography, and methods of detection including
flame ionization and mass spectrometry.
-- PAHs: Gas chromatography with flame ionization or mass
spectrometric detection, or liquid chromatography, is used after
solvent extraction. As PAHs are poorly resolved from the diesel
fuel matrix, gas chromatography-mass spectrometry is necessary in
most cases to quantify the components. The target analytes of
commonly used analytical methods do not, however, include C3
and C4 alkyl-substituted benzenes or most alkyl-substituted
PAHs in diesel fuels.
Table 6. Physicochemical properties of aromatic components of diesel fuel
Aromatic compound Water solubility Henry's law constant Diffusion coefficient (cm2/s) Octanol-water partition
(mg/litre) (Pa × m3/mol) In air In water coefficient (log Pow)
Benzene 1791 550 0.087 9.8 × 10-6 1.99
Toluene 534.8 602 0.083 8.6 × 10-6 2.52
Ethylbenzene 161.0 855 0.076 7.8 × 10-6 2.94
Xylene 156.0 778 0.076 1 × 10-5 2.94
Polycyclic aromatic 0.067 0.007 0.067 2.12 × 10-6 5.30
hydrocarbons
Adapted from Custance et al. (1993)
A2.4 Conversion factors
As diesel fuel vapour is a complex mixture of gases, it is
impossible to give a conversion factor for converting parts per
million in the gaseous phase to SI units.
A3. SOURCES OF HUMAN AND ENVIRONMENTAL EXPOSURE
A3.1 Natural occurrence
Diesel fuels are derived from crude oil, which can be considered
a 'natural product'. Nevertheless, human and environmental exposure
results almost exclusively from anthropogenic activities.
A3.2 Anthropogenic sources
A3.2.1 Production and use
A3.2.1.1 Production process
Diesel fuel is produced during the refining of crude oils but is
generally blended to meet the specifications for technical
performance. The blending components may be produced by atmospheric
distillation of crude oil (straight-run atmospheric gas oil), vacuum
distillation of atmospheric residue (vacuum gas oil), thermal cracking
(thermally cracked gas oil), or catalytic cracking processes (e.g.
light catalytically cracked gas oil; cycle oil). The main components
are straight-run gas oils: 80% of European automotive diesel fuel is
made up of these components (Booth & Reglitzky, 1991). Secondary
processing of heavier fractions is increasingly necessary in order to
meet product demand (CONCAWE, in press).
Diesel fuel No. 1 is manufactured by a straight-run distillate
process (Agency for Toxic Substances and Disease Registry, 1995);
diesel fuel No. 2 is generally made by mixing straight-run and
catalytically cracked distillates; and diesel fuel No. 4 is produced
by adding blending stocks to distillation residues in order to meet
viscosity specifications (International Agency for Research on Cancer,
1989a). Further variations are introduced by formulation with
additives to improve fuel properties (see section A2.1.2).
A3.2.1.2 Use
Diesel fuel is widely used as a transport fuel for light- and
heavy-duty vehicles; the Organisation for Economic Co-operation and
Development (1993) classifies vehicles weighing < 3.5 t as light-duty
and those weighing > 3.5 or, occasionally, > 5 t as heavy-duty.
Diesel fuel No. 1 is suitable for engines that undergo frequent
changes in speed and load (Agency for Toxic Substances and Disease
Registry, 1995). Heavier grades (diesel fuels No. 2 and 4) are used
for trucks, railroad and marine diesel engines, and stationary engines
in continuous high-load service (Sandmeyer, 1981; International Agency
for Research on Cancer, 1989a). Diesel fuels are also used in
stationary gas turbines, e.g. to generate electric power during
peak-load periods. Residual fuel oils, such as diesel fuel No. 4, are
used to generate steam in electric power plants (International Agency
for Research on Cancer, 1989a), in commercial and industrial burner
installations without preheating facilities, in plants and factories
for space and water heating, for pipeline pumping, and in gas
compression; they are also sprayed on unmade roads to compact the
surface and are used in the manufacture of asphalt cement (Agency for
Toxic Substances and Disease Registry, 1995).
A3.2.1.3 Production and consumption levels
The demand for diesel fuel has increased worldwide over time. In
1990, world demand was about 1100 kt/day (Booth & Reglitzky, 1991).
The production and consumption of diesel fuel in different regions
over time are shown in Table 7.
Diesel-fuelled passenger cars are relatively common in western
Europe. The percentages of passenger cars with diesel engines in
various European countries over time are shown in Table 8. In many
European countries, taxi-cabs are equipped almost exclusively with
diesel engines. In 1985, diesel-fuelled heavy-duty trucks comprised
about 86% of the fleet in Norway, 89% in Denmark, 95% in Sweden, and
100% in the former Federal Republic of Germany. In some countries of
Europe, diesel fuel consumption has increased steadily over the last
decade, and consumption for heavy-duty vehicles is predicted to more
than double between 1980 and 2005 (Organisation for Economic
Co-operation and Development, 1993). In western Germany, diesel fuel
consumption was almost 60% higher in 1990 (about 5100 kt) than in 1984
(about 3200 kt) (Federal Ministry for Transport, 1992).
Diesel-fuelled passenger cars are less common in North America.
In the United States in 1986, about 1.6% of passenger cars were
diesel-fuelled, and the tendency was predicted to decrease slightly
(US Department of Energy, 1988). In contrast, 82% of heavy-duty trucks
were diesel-fuelled in 1985 (Organisation for Economic Co-operation
and Development, 1993), and 59300 kt of diesel fuel were consumed by
highway traffic in 1986, representing 14.8% of all the highway fuel
used and about one-half of United States diesel fuel consumption.
On-road use of diesel fuel was predicted to increase to 15.5% of all
highway fuel (66600 kt) in 1995. A difference in fuel use patterns is
seen between light- and heavy-duty vehicles. In 1986, about 4000 kt
were used by passenger cars and light trucks, with an estimate of
about 2300 kt for 1995, whereas in 1986 about 55300 kt were used by
heavy-duty trucks, with an estimate of 64300 kt for 1995 (US
Department of Energy, 1988). In Canada, only about 1% of passenger
cars are equipped with diesel engines. In 1992, 14126 kt of diesel
fuel were produced; 13508 kt were sold for domestic purposes (heating)
and about 10849 kt for on-road use (Thomas, personal communication,
1994).
The percentage of diesel-fuelled vehicles is increasing in Japan
(Table 9).
Table 7. Production and use of diesel fuel (including gas oils in
Europe) in different regions, and development over time
Region Production/ 1975 (kt) 1980 (kt) 1985 (kt)
Use
United States Production 134 967 138 323 135 181
Use 133 300 136 161 130 297
Canada Production 19 187
Use 19 130
OECD (all 24 Production 370 240 408 848 372 728
countries) Use 380 181 403 642 386 081
OECD (Europe) Production 173 474
Use 190 960
European Union Production 152 091
Use 163 132
Australia, Japan, Production 44 886
New Zealand Use 45 694
Adapted from International Agency for Research on Cancer (1989a);
OECD, Organisation for Economic Co-operation and Development
A3.2.2 Emissions during production and use
A3.2.2.1 Air
No data are available on emissions during the production and use
of diesel fuel. Release to the atmosphere during production in the
refining process is unlikely, as closed systems are used, but
volatilization may occur during storage and transport. Diesel fuel may
be released into the atmosphere as a result of spills during storage
and transport and at filling stations during bulk storage and vehicle
tank filling. The low-relative-molecular-mass constituents
(short-chain alkanes, benzene, toluene, ethyl benzene, and xylene
compounds) are the most likely to evaporate under environmental
conditions.
Table 8. Percentage of diesel passenger cars in western Europe, and
development over time
Country Diesel passenger cars (%)
1984 1988 1991 1992a
France 15.8 21.1 25.5 38
Germany (without former 16.9 15.1 15.3 14.9
German Democratic Republic) (1993)b
Germany (without former About 8 13.6 13
German Democratic Republic)c
Italy 18.7 11.9 7.4 NR
Spain (without station wagons) 15.3 10.5 14.6 NR
United Kingdom 1.1 4.5 11.3 12.5
United Kingdomd NR 5 9 19 (1993)
Adapted from American Automobile Manufacturers Association (1993),
unless otherwise stated; NR, not reported
a From Menne et al. (1994)
b With the former German Democratic Republic
c From German Institute for Scientific Research (1993)
d From Quality of Urban Air Review Group (1993)
Table 9. Percentage of diesel-fuelled vehicles in Japan and
development over time
Year Passenger cars (%) Trucks (%) Buses (%)
1984 3.8 23.7 49.5
1988 5.8 28.5 63.2
1991 8.3 40.7 81.7
Adapted from American Automobile Manufacturers Association (1993)
A3.2.2.2 Water
No data are available on effluents and emissions during diesel
fuel production. Diesel fuel oils may be released to surface waters as
a result of leakage from storage tanks or tankers (see section
A3.2.3). In the United States, the total volumes of spills of diesel
fuel oils in 1991 were (Agency for Toxic Substances and Disease
Registry, 1993): diesel fuel No. 1, 10.6 t (20 notations); diesel fuel
No. 2, 8.9 t (28 notations); and diesel fuel No. 4, 39.3 t (35
notations).
Groundwater can be contaminated with diesel fuel constituents by
leakage from underground bulk storage tanks, but quantitative data are
lacking. In the Province of New Brunswick, Canada (Thomas, personal
communication, 1993), of a total of 671 gasoline, diesel, and fuel oil
tanks examined in 1987, 11% leaked diesel or fuel oil; in 1989, 6% of
1085 tanks had leaks; and in 1991, 13% of 539 tanks leaked fuel. No
data were available about the amounts leaked, and diesel contamination
was determined on the basis of a cluster of 'middle-range peaks'
detected by gas chromatography.
On the basis of chronic petroleum inputs to sediments of
Narragansett Bay and Rhode Island Sound, United States, Van Vleet &
Quinn (1978) estimated that about 200 kt of petroleum hydrocarbons may
be released to surface waters worldwide from municipal treatment
plants. The precise source of the inputs cannot be verified in most
cases, but they are due, for example, to accidental discharge to sewer
systems, disposal of used crankcase and lubricating oils, oil washed
from roads, and atmospheric deposition of hydrocarbons.
No data were available from other countries.
A3.2.2.3 Soil
Diesel fuels may be released to soil as a result of accidental
spills (see section A3.2.3) and leakage from storage tanks or
pipelines. Diesel-contaminated soil is a major problem in railroad
yards, where diesel fuel is used in locomotives and as a solvent to
clean moving metal parts (the remaining paraffins give a waxy
anti-corrosive coat). Spillage during refuelling, engine maintenance,
and steam cleaning, leakage from fuel storage tanks, and absorption of
diesel fuel on sand used for traction are other possible sources of
soil contamination (Dineen, 1991); however, no quantitative data are
available.
A3.2.3 Accidental releases to the environment
Data on the accidental release of diesel fuels are summarized in
Table 10. The effects on the environment depend on both the amount and
environmental conditions.
Table 10. Diesel fuel spills and their effects on the environment (see also section A9.2)
Year Place Amount (t); type Effects Reference
of diesel fuela
Aquatic environment
1972 North of Puget Sound, > 600; diesel fuel Substantial mortality of some intertidal taxa; Woodin et al. (1972)
Washington State, USA No. 2 larval recruitment within six months
1973 East Lamma Channel 2000-3000; Almost total kill of meiofauna within four days; Wormald (1976);
near Hong Kong diesel fuel No. 4 heavy mortality among bivalves and molluscs, Stirling (1977)
Nerita albicilla and Monodonta labio, and in
marine fish farms; almost no effect on
Clypeomorus humilis or Planaxis sulcatus
1978 Svea, Mijenfjord, Norway 111 Most fuel trapped in ice; transport out of fjord Carstens &
during break-up; heavy mortality among shoreline Sendstad (1979)
invertebrates in some regions of fjord
1983 Yaquina Bay, Oregon, About 240 (with Decline in population of Rhepoxynius abronius Kemp et al. (1986)
USA Bunker C oil) by 75%; influence of spill not clear
1984 Queen Charlotte 130 (plus 30 t Low fuel levels in water during flood tide, high McLaren (1985)
Islands, Canada gasoline) levels during ebb as diesel was retained in
sediment; high mortality among barnacles
Table 10 (contd)
Year Place Amount (t); type Effects Reference
of diesel fuela
1987 Macquarie Island, 230; diesel fuel High mortality among one species of holothuroid, Pople et al. (1990)
Australia No. 4 one of isopod, one of limpet, and one of chiton;
decreased populations of crab, two species of
starfish, and gastropod; small number of dead
algae; slow recovery of organisms
1989 Arthur Harbor, 510; diesel fuel High mortality among limpets; partial recovery one Kennicutt et al.
Antarctica No. 1 year after spill; small effect on macroalgae (1991a,b,1992a,b)
Terrestrial environment
1983 San Bernadino County, 3 Hydrocarbon contamination up to 1500 mg/kg; Frankenberger et al.
CA, USA plume migrating towards surface water; in-situ (1989)
bioremediation (see also section A3.2.4)
NR Califonia, USA 193; diesel fuel Contamination at 6-34 m below surface; Peters et al. (1992)
No. 2 hydrocarbon levels at 18.3, about 1500 mg/kg;
remediation by flooding with surfactants
(see also section A3.2.4)
aWhen available
A4. ENVIRONMENTAL TRANSPORT, DISTRIBUTION, AND TRANSFORMATION
Few data are available on the environmental fate of diesel
fuels, but there are adequate data on the environmental behaviour of
individual hydrocarbon components. The transport, distribution, and
transformation of crude oils and some fuel oils (e.g. heating oils
No. 1 and 2) have been studied, and the mechanisms of distribution and
transformation are considered to be comparable to those of diesel
fuel.
The calculated half-lives for the toxicologically relevant PAH
components are listed in Table 11.
A4.1 Transport and distribution between media
Diesel fuels are released into the environment mainly during
storage, transport, and use (see section A3.2.3). The hydrosphere and
geosphere are the affected compartments.
A4.1.1 Evaporation from and dissolution in the aqueous phase
Oils and fuels spilled on water spread out almost immedia