About Guidelines for Developing ESLs, ReVs, and URFs
Guidelines to Develop Toxicity Factors: A New Public Comment Period Has Begun!!
The Toxicology Division is accepting toxicity information!!
- Guidelines for Developing ESLs, ReVs, and URFs
- Intended Use of Guidelines for Developing ESLs, ReVs, and URFs
- Interim Guidelines for Setting Odor-Based Effects Screening Levels
- Process for Requesting ESLs
- Sign Up to Receive ESL List, AMCV List, and Other Toxicology Announcements
Guidelines for Developing ESLs, ReVs, and URFs
This regulatory guidance document, Guidelines to Develop Effects Screening Levels, Reference Values, and Unit Risk Factors (RG-442) was finalized in 2006.
The guide is presented in five chapters. Chapter 1 addresses several fundamental topics, including legal authority and regulatory use, consideration of cumulative risk, and opportunities for public participation. Chapter 1 also describes how welfare-based ESLs are set, and introduces ReVs and URFs and their use in calculating health-based ESLs. Chapter 2 discusses procedures common to derivation of both acute and chronic toxicity values. Chapter 3 addresses the procedures that are unique to the derivation of acute ReVs, and Chapter 4 addresses those that are unique to the derivation of chronic ReVs and URFs. Chapter 5 discusses the treatment of chemical groups and mixtures.
Intended Use of Guidelines for Developing ESLs, ReVs, and URFs
This is a technical guide written and used by the Toxicology Division (TD) of the TCEQ for developing Effects Screening Levels (ESLs), inhalation Reference Values (ReVs), and inhalation Unit Risk Factors (URFs). Although this document is primarily written as guidance for the Toxicology staff, it also documents (largely by reference) the processes used to develop ESLs, ReVs, and URFs for any interested person with training in inhalation toxicology and risk assessment.
ESLs are chemical-specific air concentrations set to protect human health and welfare. Short-term ESLs are based on data concerning acute health effects, the potential for odors to be a nuisance, and effects on vegetation, while long-term ESLs are based on data concerning chronic health and vegetation effects. Welfare-based ESLs (odor and vegetation) are set based on effect threshold concentrations. Health-based ESLs, however, are calculated from ReV and URF toxicity factors. ReVs and URFs are based on the most sensitive adverse health effect relevant to humans. Derivation of a ReV or URF begins with a toxicity assessment involving hazard identification and dose-response assessment based on the chemical's mode of action. The resulting ReVs and URFs are then used to calculate ESLs that correspond to no significant risk levels.
Interim Guidelines for Setting Odor-Based Effects Screening Levels
The TCEQ Toxicology Division (TD) proposes to use the following selection criteria as interim guidelines for setting an odor-based Effects Screening Level (acuteESLodor) until the TD revises its 2006 regulatory guidance document, Guidelines to Develop Effects Screening Levels, Reference Values, and Unit Risk Factors (RG-442) (TCEQ 2006).
Interim Guidelines for Setting Odor-Based Effects Screening Levels
TCEQ Response to Public Comments
Guidelines to Develop Toxicity Factors: A New Public Comment Period Has Begun
Since 2006, new scientific developments in toxicology and risk assessment have resulted in changes to some risk assessment approaches. As a result, the TD has prepared new guidelines that will be entitled "TCEQ Guidelines to Develop Toxicity Factors."
The revised guidelines contains significant revisions since 2006 including changes to the procedures for developing odor -based ESLs, consideration of the differences between children and adults when assessing risk, identification of health-based effect levels, development of 24-hour acute reference values, guidance on how to determine if an effect is adverse, hazard identification and dose-response modeling of epidemiology studies, and development of oral reference dose (RfD) and oral cancer slope factor (SFo) values.
The public comment period for the revision of the TCEQ Guidelines to Develop Toxicity Factors has begun and will close in 60 days. Because of the sweeping changes made to the Guidelines, the revision underwent a letter peer review and public comment period in June of 2011, organized by Toxicology Excellence for Risk Assessment (TERA). This draft for the revision of the TCEQ Guidelines to Develop Toxicity Factors incorporated comments from the Peer Review Report that increased the scientific and technical merit and clarity of the Guidelines. The responses to the Peer Reviewer Comments are also now available. Click on the following links to view the documents:
TCEQ Guidelines to Develop Toxicity Factors
Texas Commission on Environmental Quality Responses to Peer Review Report
Procedures to Submit Comments
Submit comments by e-mail to tox@tceq.texas.gov or by mail (must be received at the TCEQ no later than June 8, 2012) to:
Regular mail:
Toxicology Division, MC 168
Texas Commission on Environmental Quality
P.O. Box 13087
Austin, TX 78711-3087
Mail delivery services:
Toxicology Division, MC 168
Texas Commission on Environmental Quality
12100 Park 35 Circle, Bldg. F
Austin, TX 78753
Contact the TCEQ About DSDs and Fact Sheets
Call: 877-992-8370 (toll free) or 512-239-1795
E-mail: tox@tceq.texas.gov
Write:
Texas Commission on Environmental Quality
Toxicology Division, MC 168
P.O. Box 13087
Process for Requesting ESLs
Individuals who would like to request an ESL from the Toxicology Division should first check the ESL list to see if the ESL they are requesting is already available. Be sure to search by Chemical Abstract Service (CAS) number since many chemicals have synonyms.
If the ESL is not available on the 2007 ESL list, please contact Dr. Jong-Song Lee (jlee@tceq.texas.gov or 512-239-1790) to request an ESL.
Sign Up to Receive ESL List, AMCV List, and Other Toxicology Announcements
To join the Toxicology Announcement List, please e-mail:
join-tox@listserv.tceq.state.tx.us
Do not put any information in either the subject or message body.
You will automatically receive an acknowledgment by e-mail informing you that your request has been received; however, you must confirm that you wish to be placed on the list. To confirm, reply to the message.
Once the list administrator has admitted your e-mail address to the list, you will receive a “welcome” document.
