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Characterisation Method Information
Characterisation Method Name:
Benzene impact on wood
Version:
1999
Date Completed:
1999
Principal Method Name:
EPS: Global warming pathway
Method Description:
Model

The characterisation factor is determined by an equivalency method using CO2 as a reference.
There are two pathways for CO2s impact on forest growth. One is the global warming and the other is CO2 fertilisation. The CO2 fertilisation is more than 30 times as efficient as the global warming. Considering the GWP100 for benzene being 11 and the
equivalency for CO2 fertilisation being 46/13 = 3.54, the CO2 fertilisation pathway is still 10 times as efficient. Therefore the model will focus on the equivalency with CO2 in the fertilising aspect.

Equivalency factor

The equivalency for CO2 fertilisation was calculated above to 46/13 = 3.54. 46 is the
molecular weight of CO2 and 13 a sixth of the molecular weight of benzene. (each benzene molecule will give six CO2 molecules when it is oxidised. It is assumed that all benzene is oxidised sooner or later to CO2 and water.

Calculation of characterisation factor

As the fertilisation pathway specific characterisation factor of CO2 for wood is 3.93E-02 kg wood/kg CO2 we obtain the pathway specific characterisation factor of benzene to wood to 3.54*(-3.93E-02 ) = -1.39E-01 kg wood/kg benzene.
Literature Reference:
Steen B (1999b): A systematic approach to environmental priority strategies in product development (EPS). Version 2000 Models and data of the default method CPM report Chalmers University of Technology Sweden
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 wood
Characterisation Parameter Category Indicator Impact Indication Principle Aspect Substance Quantity Unit Notes
CFactor Wood EPS/2000
Type = Emission
Direction = Output
Media = Air
Geography = *
Benzene -1.39E-01 kg/kg Global warming