What are the sources of toxicity values used on this site?
In 2003, EPA’s Superfund program revised its hierarchy of human health toxicity values (PDF) (4 pp, 228 K), providing three tiers of toxicity values . Three tier 3 sources were identified in that guidance, but it was acknowledged that additional tier 3 sources may exist. The 2003 guidance did not attempt to rank or put the identified tier 3 sources into a hierarchy of their own. However, when developing the screening tables and calculator presented on this website, EPA needed to establish a hierarchy among the tier 3 sources. The toxicity values used as “defaults” in these tables and calculator are consistent with the 2003 guidance. Toxicity values from the following sources in the order in which they are presented below are used as the defaults in these tables and calculator. • • EPA’s Integrated Risk Information System (IRIS) • The Provisional Peer Reviewed Toxicity Values (PPRTVs) derived by EPA’s Superfund Health Risk Technical Support Center (STSC) for the EPA Superfund program. (
In 2003, EPA’s Superfund program revised its hierarchy of human health toxicity values, providing three tiers of toxicity values (http://www.epa.gov/oswer/riskassessment/pdf/hhmemo.pdf). Three tier 3 sources were identified in that guidance, but it was acknowledged that additional tier 3 sources may exist. The 2003 guidance did not attempt to rank or put the identified tier 3 sources into a hierarchy of their own. However, when developing the screening tables and calculator presented on this website, EPA needed to establish a hierarchy among the tier 3 sources. The toxicity values used as “defaults” in these tables and calculator are consistent with the 2003 guidance. Toxicity values from the following sources in the order in which they are presented below are used as the defaults in these tables and calculator. • EPA’s Integrated Risk Information System (IRIS) • The Provisional Peer Reviewed Toxicity Values (PPRTVs) derived by EPA’s Superfund Health Risk Technical Support Center (STSC
