65
Quantifying Toxicity
• A chemical-specific TF of greater than 1 dose/capita-lb (e.g., 500 doses/
capita-lb) represents the fact that each of the 306 million people in the United
States has 500 times the potential to reach the threshold beyond which an
adverse effect can occur from sharing 1 lb of that chemical (carcino genic or
noncarcinogenic), assuming exposure and intake (ingestion or inhalation)
are equal across the population.
• A chemical-specific TF of less than 1 dose/capita-lb (e.g., 0.06 doses/capita-lb)
represents the fact that less than 306 million people in the United States will
be exposed to the threshold beyond which an adverse effect (carcinogenic
or noncarcinogenic) can occur from sharing 1 lb of that chemical, assuming
exposure and intake (ingestion or inhalation) are equal across the population.
The TRI chemicals for which measures of toxicity were not available are not
included in Table 6.1.
In the next few chapters of this book, factors for mobility (Chapter 7), persistence
(Chapter 8), and bioconcentration (Chapter 9) are developed for the TRI chemicals.
Subsequently, in Chapter 10, these factors are integrated into the chemical-specific
TFs developed in this chapter to come up with effective toxicity factors (ETFs) that
can then be used to evaluate the relative impacts of the various TRI chemical releases.
The purpose of this is to develop a better overall relative toxicity index of releases
rather than volume alone to guide policy in reducing these releases, as compared to
the present system of reporting on and reducing the total volume of these releases
regardless of relative toxicity.
Quantifying Toxicity
• A chemical-specific TF of greater than 1 dose/capita-lb (e.g., 500 doses/
capita-lb) represents the fact that each of the 306 million people in the United
States has 500 times the potential to reach the threshold beyond which an
adverse effect can occur from sharing 1 lb of that chemical (carcino genic or
noncarcinogenic), assuming exposure and intake (ingestion or inhalation)
are equal across the population.
• A chemical-specific TF of less than 1 dose/capita-lb (e.g., 0.06 doses/capita-lb)
represents the fact that less than 306 million people in the United States will
be exposed to the threshold beyond which an adverse effect (carcinogenic
or noncarcinogenic) can occur from sharing 1 lb of that chemical, assuming
exposure and intake (ingestion or inhalation) are equal across the population.
The TRI chemicals for which measures of toxicity were not available are not
included in Table 6.1.
In the next few chapters of this book, factors for mobility (Chapter 7), persistence
(Chapter 8), and bioconcentration (Chapter 9) are developed for the TRI chemicals.
Subsequently, in Chapter 10, these factors are integrated into the chemical-specific
TFs developed in this chapter to come up with effective toxicity factors (ETFs) that
can then be used to evaluate the relative impacts of the various TRI chemical releases.
The purpose of this is to develop a better overall relative toxicity index of releases
rather than volume alone to guide policy in reducing these releases, as compared to
the present system of reporting on and reducing the total volume of these releases
regardless of relative toxicity.