ITSL/IRSL Field Descriptions

CAS Number:

Chemical Abstracts Service number

Chemical Name:

Name of the chemical

Notes:

Special conditions which may apply to how screening levels are determined for specific chemicals. If a number appears in this column, see the bottom of the search results page for a description of what the number indicates.

Status:

Limits may be either Interim or Final

ITSL (ug/m3):

Initial Threshhold Screening Level - A concentration of toxic air contaminant in the ambient air which is used to evaluate noncarcinogenic health effects from a proposed new or modified process and which is calculated, for regulatory purposes, according to the procedure in R 336.1229(2).

Averaging Time:

Averaging period for the Initial Threshold Screening Level

Second ITSL (ug/m3):

Second Initial Threshold Screening Level

Second ITSL Avg Time:

Averaging period for the Second Initial Threshold Screening Level

IRSL (ug/m3):

Initial Risk Screening Level - the concentration of a possible, probable, or known human carcinogen in ambient air which has been calculated for regulatory purposes, according to the risk assessment procedures in R 336.1229(1), to produce an estimated upper-bound lifetime cancer risk of 1 in 1,000,000

SRSL (ug/m3):

Secondary Risk Screening Level - the concentration of a possible, probable, or known human carcinogen in ambient air which has been calculated for regulatory purposes, according to the risk assessment procedures in R 336.1229(1), to produce an estimated upper-bound lifetime cancer risk of 1 in 100,000

Carc Avg Time:

Averaging time period for the Initial Risk Screening Level and Secondary Risk Screening Level