WHAT DO THE SCORES MEAN?
Noncancer risk scores indicate how a chemical compares with others in terms of the potential health risks posed by release of one pound to water. The graphic shows where a chemical's water noncancer score falls relative to all chemicals that have been ranked using this website's system, and indicates whether a chemical is more or less toxic than most chemicals. Chemicals that score at the far right end of the scale are significantly more hazardous (in the worst 10% according to this scoring system).
All chemicals scored by a system are placed in "bins" defined by percentiles (e.g., a chemical's score is in the least toxic 25% of chemicals scored by a system). The graphic illustrates which bin a chemical falls in according to each scoring system in Scorecard. Looking across these different systems, it is possible to
identify chemicals that consistently score as high or low hazards, as well as chemicals that score high on some measures (such as human health hazards) but low on others (such as ecological hazards).
NONCANCER RISK SCORE - WATER RELEASES (EDF) FOR DIAZINON
Noncancer Risk Score - Water Releases (EDF) = 980
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 noncancer risk scores, risk assessment values are combined with CalTOX doses to calcualte a hazard index using the conventional approach to noncancer risk characterization:
Hazard Index = Average Daily Dose from Exposure/Reference Dose
To obtain a Noncancer Risk Score for a chemical released to water, the hazard index resulting from a one pound release of that chemical to water is normalized by the hazard index for a one pound release of toluene to water. The units of Noncancer Risk Scores are pounds of toluene-equivalents. To obtain a single common denominator of toluene-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).