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Characterisation Method Information
Characterisation Method Name:
Benzene impact on YOLL
Version:
1999
Date Completed:
1999
Principal Method Name:
EPS: cancer pathway, global warming and oxidation pathways
Method Description:
YOLL stands for Year of Lost Life.

Model 1, Cancer pathway

The characterisation factor is determined by the empirical method.

Category indicator value in system considered
The average population-weighted benzene concentration in Sweden 1985 was 3.7 mg/m 3 (Boström et al., 1994). The average population-weighted NO2-concentration was
determined to 23 mg/m3 and was used as a tracer for car exhaust. The average population-weighted benzene exposure was determined from the ratio of NOx to benzene
measured in several Swedish cities. The average 1990 NOx-concentration in USA may be estimated from the yearly averages of 120 monitor sites to 0.030 ppm or 62 mg/m 3
(USEPA 1999). This would indicate an average concentration of 10 mg/m 3 of benzene.
The measured 1990 average concentration of 64 monitoring
stations was 6 mg/m 3 (USEPA 1999). Shah and Sing (1988) reported average US benzene concentrations of 2.8
ppbv, which corresponds to 9.7 mg/m 3 .

For the present global population an average decrease in life expectancy is determined to 22.8 years (the sum of all YOLL’s divided by the total number of mortal cancers)

As the cancer statistics is based on present figures and present distribution of ages of the global population an increase in the average YOLL from cancers may be expected as the average age increases. If WHO figures for the population distribution 2025 is used, the average decrease in life expectancy is 25.5 years. Assuming an incubation time of 20 years an appropriate figure would be around 24 years. This means that as the global average life expectancy is 65 years and if, as an average,
1/65 of 1990 years population is assumed to die each year, there are 5.28E+09 *0.64*5E-06*10*24/65 = 6.24E+04 YOLL during 1990.

Contribution to category indicators value from a flow unit

The main source of benzene is from car traffic. Emission ratio for real world traffic for benzene and CO may be estimated from street level measurements or measurements in road tunnels. The benzene/CO-ratio was determined in Stockholm by Persson and Almen (1990) and in a Brussel road tunnel by Vanderstraeten et al. (1991). Persson and Almen found a ratio of 0.0011 and Vanderstraeten et al. a ratio of 0.0068, both on weight basis.

Gabele (1995) measured exhaust emissions from in-use vehicles with various fuels and
found a ratio in the order of 0.001. Based on this, a best estimate of 0.002 is made.
The global anthropogenic CO emission was estimated to 1600 million tonnes.
Therefore the global anthropogenic benzene emission may be estimated to 0.002*1600 = 3.2 million tonnes and the average contribution to 1/(3.2×10 9 ) = 3.12×10 -10 per kg benzene.

Calculation of pathway specific characterisation factor

The characterisation factor will thus be 6.24E+04 *3.12E-10 = 1.95E-05 YOLL/kg benzene

Model 2, global warming pathway
The characterisation factor is determined by an equivalency method using CO2 as a
reference.

Equivalency factor
The GWP100 was estimated by IPCC to 11 in one of the early reports. (1990). Later this
statement was withdrawn by IPCC, with the motivation that the uncertainty was too
large. In the EPS context however, omitting it would create a larger error than including
it, so the equivalency factor 11 will still be used.

Calculation of pathway specific characterisation factor

The characterisation factor of CO2 for YOLL was determined in 3.1.3 to 7.93E–07
YOLL/kg CO2 . The characterisation factor of benzene for YOLL will therefore be
11*7.93E–07 = 8.72E–06 YOLL/kg benzene.

Model 3, photochemical oxidant formation pathway

The characterisation factor is determined by an equivalency method using ethylene as a reference.

Equivalency factor

Benzene has a photochemical peak oxidant formation potential (POCP-1) of 0.317
(Lindfors et.al 1994) relative to ethylene.

Calculation of pathway specific characterisation factor

The oxidant pathway specific characterisation factor of ethylene for YOLL in the oxidant pathway is determined to 1.20E-05 YOLL/kg ethylene. The oxidant pathway specific characterisation factor of benzene for YOLL is therefore 0.317*1.20E-05 = 3.80E-06 YOLL/kg benzene.

Calculation of characterisation factor

The characterisation factor for the added impacts from all pathways is 1.95E-05 +
8.72E–06 + 3.80E-06 = 3.20E-05 YOLL/kg benzene.

Literature Reference:
1. Shah, J. and Sing, H., “Distribution of volatile organic chemicals in outdoor and indoor air. A national database”. Environ. Sci. Technol., Vol 22, No. 12, 1988. 2. UNEP/WMO, “Urban air pollution in megacities of the world”, Blackwell Publishers, Oxford, 1992. 3. Berrino, F., Capocaccia, R., Esteve, J., Gatta, G., Micheli, A., Sant, M., & Verdecchia, A. (1999) Survival of Cancer Patients in Europe in the late eighties: The EUROCARE II Study (IARC Scientific Publication No. 151) International Agency for Research on Cancer, Lyon. In press 4. Parkin, D.M., Pisani, P. and Ferlay, J., “Estimates of the worldwide mortality from 25 major cancers in 1990”. International Journal of Cancer. (In Press) 5. Persson, K. and Almén,J . , “Characterisation of light hydrocarbons and other volatile organic compounds in Stockholm air”, Swedish EPA report SNV PM 3820. Swedish Environmental Protection Agency 1990. 6.Vanderstraeten, P., Wauters, E. and Verduyn, G., Staub - Reinhaltung der Luft, Vol 51, (1991) pp. 83–90.
Methodological Range:
The residence time of benzene is in the order of days to weeks. As the regional background concentration of benzene in a rural area is low compared to the one measured in an urban area, the main contribution to the population dose occurs in urban areas close to the sources and within hours of release. The main source of benzene is cars and the gasoline fuel system. Gasoline contains several percent of benzene. This means that emissions occur worldwide and mostly at ground level. The environmental system is therefore global with a focus on urban areas. The temporal system border is the year 1990 for oxidant effects and for the cancer pathway and 100 years for the global warming pathway. The cancer pathway has a longer time scale, maybe in the order of 20 years, but the model is assuming linearity, why it does not make any difference for the model if an instant dose-response is assumed.
Notes:

Existing Characterisation Factors of Benzene impact on YOLL
Characterisation Parameter Category Indicator Impact Indication Principle Aspect Substance Quantity Unit Notes
CFactor YOLL EPS/2000
Type = Emission
Direction = Output
Media = Air
Geography = *
Benzene 3.20E-05 p yr/kg 3 pathways