Biomedical Engineering Reference
In-Depth Information
TABLE 2.6 Comparative Values of Octanol-
Water Coefficients and Bioconcentration Factors
Compound
Log K
ow
Log BCF
0.82
a
2.09
a
Methanol
0.77
a
0.75
b
0.31
b
0.16
b
0.32
a
1.63
a
Ethanol
0.31
a
0.75
b
2.13
b
1.56-2.15
b
6.8
c
Benzene
a
Mackay et al. (1992).
b
Zogorski et al. (1997).
c
RSP (1994).
bioaccumulation. However, octanol-water coefficients (K
ow
) and bio-
concentration factors for methanol and other oxygenates have been
reported (Table 2.6). Octanol-water coefficients may be used as an
indicator for bioaccumulation potential and are widely used as a
descriptor of hydrophobicity (Mackay et al., 1992). In conclusion,
methanol is expected to bioaccumulate slightly less than ethanol,
and significantly less than benzene and most other more hydrophobic
constituents in gasoline. Small quantities of methanol introduced into
mammals as a result of bioaccumulation from methanol fuel releases
may be rapidly metabolized, thus reducing any long-term effect.
Volatilization Volatilization is not a primary source of loss for metha-
nol since methanol has a low air/water partition coefficient and the rate
of biodegradation most likely exceeds the rate of volatilization. In the
environment, methanol has similar properties to ethanol and, therefore,
the volatilization rate of ethanol from surface waters can be used to
describe the relative volatilization rate of methanol. In a 1998 study, the
volatilization rates for several oxygenates and gasoline constituents
were calculated based on their chemical properties for various lake
