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Characterisation Method Information
Characterisation Method Name:
Benzene impact on crop
Version:
1999
Date Completed:
1999
Principal Method Name:
EPS: oxidant pathway and global warming pathway
Method Description:
Model 1, oxidant 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 crop loss is estimated to 4.87 kg crop/kg ethylene. The oxidant pathway specific characterisation factor
of benzene for crop loss is thus 0.317*4.87 = 1.54 kg crop/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statement was withdrawn by IPCC, with the motivation that the uncertainty was too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

As the characterisation factor of CO2 for crop loss is 7.56E–04 kg crop/kg CO2 we obtain the pathway specific characterisation factor of benzene for crop loss to
11*7.56E–04 = 8.32E-03 kg crop/kg benzene.

Calculation of characterisation factor

The characterisation factor for the added impacts from all pathways is 1.54 + 8.32E–03 =
1.55 kg crop / kg benzene

Literature Reference:
1. Lindfors, L.G.,Christiansen, K., Hoffman, L., Virtanen, Y., Juntilla, V. Leskinen, A., Hanssen, O-J., Rønning, A., Ekvall, T. and Finnveden, G., LCA-Nordic, Technical report No 10, Tema Nord 1995:503, Nordic Council of Ministers, Copenhagen 1994. 2. Houghton, J.T Jenkins, G.J. and Ephraums, J.J., (Ed.) (1990) Climate change – The IPCC scientific assessment. Cambridge University Press
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 crop
Characterisation Parameter Category Indicator Impact Indication Principle Aspect Substance Quantity Unit Notes
CFactor Crop EPS/2000
Type = Emission
Direction = Output
Media = Air
Geography = *
Benzene 1.55 kg/kg 2 pathways