TECHNICAL DETAILS ON HOW SCORES ARE DERIVED
This website calculates a risk score, or toxic equivalency potential, for a chemical by conducting a screening level risk assessment of an environmental release using the CalTOX model. CalTOX utilizes data on a pollutant's physical-chemical properties and the landscape characteristics of the environment receiving a release to model how that chemical will be distributed among seven connected environmental compartments (e.g., soil, water, air). CalTOX predicts the chemical concentrations in these compartments which will result from a release of a pollutant, taking into account transport and transformation processes that affect the pollutant. Modeling is conducted separately for a release to air or water, because chemicals have different environmental fates depending on where they are released.
CalTOX applies a multi-pathway exposure assessment model to estimated ambient concentrations to calculate the total chemical dose people may receive from a release. CalTOX produces an estimate of the average daily dose that is associated with a unit release of a chemical to air or water in a model environment, expressed in milligrams of a chemical per kilogram of body weight.
CalTOX is used to combine estimated doses with Scorecard's risk assessment values to estimate the health risks posed by a release of one pound of a chemical to air or water. To assign cancer risk scores, cancer potency values are combined with CalTOX doses to estimate added cancer risk using the conventional approach to cancer risk characterization:
Added Lifetime Cancer Risk = Average Daily Dose from Exposure x Cancer Potency Value
To obtain a Cancer Risk Score for a chemical released to water, the estimated cancer risk resulting from a one pound release of that chemical to water is normalized by the estimated cancer risk for a one pound release of benzene to water. The units of Cancer Risk Scores are pounds of benzene-equivalents. To obtain a single common denominator of benzene-equivalents, water TEPs are normalized to air TEPs.
On how CalTOX is used to calculate Risk Scores
On strengths and limitations of this type of scoring system
On assumptions made in calculating Risk Scores
On the physical-chemical data used as input to CalTOX
On the landscape parameter data used as input to CalTOX
On the exposure factor data used as input to CalTOX
On the risk assessment values used as input to CalTOX
On recent changes in TEPs
On peer-reviewed publications describing the derivation of TEPs.
HOW CAN I GET A COMPLETE LIST OF RISK SCORES?
Toxic equivalence potentials are available in a CSV file, which contains chemical name, CAS number, and TEP values (for cancer and noncancer risks from air and water releases).
CSV files can be easily opened by most word processing, spreadsheet or database applications (just be sure to let your application know you're opening a text file that is in comma-separated value format).