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Three approaches recommended for characterization
of toxicity impact potential in a life cycle impact assessment
(LCIA) are tested on a case study and compared. The two equivalency
factor methods are the Persistence, Bioaccumulation, and
Toxicity (PBT) method and the Multimedia Fate Modeling
(MFM) method using a Mackay Level III model with state-specific
environmental data. The simplified risk assessment (SRA)
method involved dispersion modeling using site-specific environmental
data. The life cycle inventory information evaluated
by all three methods was limited to manufacturing of the RDX-based
explosive in Kingsport, Tennessee. The effort to collect
site-specific environmental data and conduct air dispersion
modeling for the SRA method required about 24 times more
effort than the PBT method and about 4 times more effort than
the MFM method. Direct comparison of impact potential scores
for the three approaches were limited to inhalation toxicity scores
for nine air pollutants modeled by SRA. Correlations were made
on the rank order of the impact potential scores for the nine air
emissions evaluated for all three LCIA methods. Although the
number of chemicals compared is very limited, the best correlation
coefficient (0.96) was between the rank orders for the MFM
and the SRA methods. The minimal effort and reduced accuracy
of the PBT approach make it best suited for screening large
numbers of chemicals for further evaluation of the highest ranked
chemicals. The intermediate effort and reasonable accuracy (includes
transfers to other media) of the MFM approach make it
well suited for LCIAs involving comparative assertions or governmental
policy decisions. The maximum effort and assumption
of highest accuracy make the SRA approach suitable only
after limiting the locations of interest to a few sites by screening
with the other two approaches.