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Characterisation Method Information
Characterisation Method Name:
Ethylene impact on YOLL
Date Completed:
Principal Method Name:
EPS: cancer and oxidant pathways; global warming pathway
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 entire population on earth is exposed to ethylene. In Sweden, the population weighted average ethylene concentration is estimated by Boström et al. (1994) to 1.8 mg/m 3 . The main part comes from traffic, but 0.3 mg/m 3 from burning of wood.
In the US the average concentration at 83 monitoring stations as measured 1993 was 6.6
mg/m 3 (USEPA 1999).
In mega-cities in non-OECD countries the NOx-concentration is typically twice as high
compared to cities of similar size. (UNEP/WHO 1992) However, as half of the population in non-OECD countries lives in rural areas the average population exposure is assumed to be the same as for the OECD countries. This means that the average
population weighted ethylene exposure would be between 2 and 7 mg/m 3 . A best estimate of 4 mg/m 3 is assumed. IARC (International Association for Research on Cancer) has not classified ethylene as a human carcinogen. However, about 5% of ethylene is metabolised to ethylene oxide giving a net lifetime risk of 10 -5 for 1 ppb ethylene (Victorin, 1998). This corresponds to about the same risk expressed in mg/m 3 .
Mortality for all sorts of cancer in the European union was 62 % 1990. (Berrino 1999). The global average 1990 may be calculated to 64% using statistics from IARC.
(Parkin et al., 1990, Pisani et al.,1990). The average reduction of life expectancy was
estimated in "Benzene impact on YOLL" to 24 years. The global average life expectancy at birth is 65 years. This means that there are 5.28E+09 *0.64E-05 *4*24/65 = 4.99E+04 YOLL during 1990.

Contribution to category
indicators value from a flow unit

The main source of ethylene is from car traffic and from burning of wood. Emission ratio for real world traffic for ethylene and CO may be estimated from street level
measurements or measurements in road tunnels. The ethylene/CO-ratio was determined in Stockholm by Almén and Persson (1990). They found a ratio of 0.0059 on weight basis.

The global anthropogenic CO emission was estimated to 1600 million tonnes. Therefore the global anthropogenic benzene emission from traffic may be estimated to 0.0059*1600 = 9.44 million tonnes. Emissions from burning of wood are not known at present but is assumed to be of less importance than the emissions from traffic. This means that the average contribution to 1/(9.44×10 9 ) = 1.06E-10 per kg ethylene.

Calculation of pathway specific characterisation factor

The characterisation factor will thus be 4.99E+04 * 1.06E-10 = 5.29E-06 YOLL/kg ethylene.

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 to 7.93E–07 YOLL/kg CO2 . The characterisation factor of ethylene for YOLL will therefore be 11*7.93E–07 = 8.72E–06 YOLL/kg ethylene.

Model 3, oxidant formation pathway

The characterisation factor is determined by the empirical method.

Category indicator value in system considered
The excess mortality due to ozone was estimated in "NOx impact on YOLL" to 5.28×10 5 YOLL.

Contribution to category indicators value from a flow unit

In some areas NOx is rate limiting for the production of ozone, in some areas it is VOC.
Lacking good quantitative estimates of which part of the population living in areas where
VOC is rate limiting a 50% value will be used. The global anthropogenic VOC emissions
are in the order of 40 tg/year according to Stern (1986). Ethylene exhibits about 3-4% of
the VOC (Lewis et al. 1999, Colbeck and Mackenzie 1994). This means that the global
ethylene emissions are in the order of 1.4 tg/year. The average contribution from VOC is
0.5*(40E+09 )-1 = 1.25E-11 per kg. As ethylene is somewhat more potent oxidant precursor than the average, 1.8 times, the contribution is somewhat higher.
Not knowing the percentage of other VOC substances and their share of the global VOC
emissions, an approximate correction has to be made. In this the average contribution is
multiplied with 1.8, i.e. the resulting contribution will be 2.27E-11 per kg ethylene.

Calculation of pathway specific characterisation factor

The oxidant formation specific characterisation factor of ethylene for YOLL is therefore 5.28E+05 *2.27E-11 = 1.20E-05 YOLL/kg ethylene

Calculation of characterisation factor

The resulting characterisation factor from adding the three pathways is 2.02E-06 +
8.72E–06 + 1.20E-05 = 2.27E-05 YOLL/kg ethylene.

Literature Reference:
1. Boström, C-E., Almén, J., Steen, B. and Westerholm, R., “Human Exposure to Air Pollution” Environmental Health Perspectives, Vol 102, Suppplement 4, October 1994, p.39-47. 2. USEPA, AIRS web database, 1999. 3.UNEP/WMO, “Urban air pollution in megacities of the world”, Blackwell Publishers, Oxford, 1992. 4. 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 5. Victorin, K., “Risk assessment of carcinogenic air pollutants”, IMM-report 1/98, Karolinska institutet, Stockholm 1998. 6. 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) 7. Stern, A.C., “Air Pollution” Vol VI, Academic Press, 1986 8. Lewis, C., Stevens, R., Rasmussen, R., Cardelino, C. and Pierce, T. , “Biogenic Fraction of Ambient VOC: Comparison of Radiocarbon, Chromatographic, and Emissions Inventory Estimates for Atlanta, Georgia”, J. Air & Waste Manage. Assoc., Vol 49, pp.299-307, (1999) 9. Colbeck, I. and Mackenzie, A., “Air Pollution by photochemical oxidants”, Elsevier, Amsterdam 1994.
Methodological Range:
Including emissions from anywhere at the globe 1990 and considering a residence time of several days for ethylene and its reaction products, the environmental system will also be global. As ethylene causes cancer, there is a reason for using a 20-year system border, but as we use a linear dose-response model, we restrict the system borders to the year 1990. In terms of qualitative system borders, we look at human health issues and ecosystem production capacity. No effects on biodiversity, resources or aesthetics are included. For the global warming pathways the same system borders as for CO2 is relevant, i.e. 100 years.

Existing Characterisation Factors of Ethylene 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 = *
Ethylene 2.27E-05 p yr/kg 3 pathways