IRIS Public Science Meeting (Nov 2021)
[UPDATE] The postponed IRIS Public Science Meeting for Naphthalene has been re-scheduled to November 9, 2021. See Meeting Details for more information.
The IRIS Program convenes IRIS Public Science Meetings to encourage the scientific community and the public to participate in discussions on IRIS draft assessment materials.
At this meeting, the IRIS Program invites the public to the discussion on the key science issues identified in the following document:
- IRIS Assessment Plan (IAP) for Naphthalene.
During Fiscal Year 2018, EPA prioritized its IRIS assessments to meet the highest needs of EPA Programs and Regions (see April 2019 IRIS Program Outlook). At that time, the IRIS Assessment of naphthalene was not identified as a priority and was suspended. The assessment was suspended after release of the IRIS Assessment Plan for public comment in July 2018, but before a public science meeting could be held to discuss the IRIS Assessment Plan
In Fiscal Year 2021, naphthalene was renominated as a priority for assessment, and has been unsuspended (see June 2021 IRIS Program Outlook). EPA is resuming rescheduling this public meeting to discuss the key science issues identified in the IRIS Assessment Plan for Naphthalene (see 83 FR 31388). Comments previously submitted to EPA during the public comment period for this IAP document may be reviewed by visiting Regulations.Gov (Docket No. EPA-HQ-ORD-2014-0527).
Following the public meeting, a revised version of the IAP will be included as part of the IRIS systematic review protocol for naphthalene, which will be released for public comment in Fiscal Year 2022.
- The meeting will be held by webinar on Nov 9, 2021 from 1:00 - 3:00pm ET.
- Meeting registration will be open from Sep 30, 2021 until Nov 7, 2021.
- Register to be a public commenter by Oct 25, 2021.
- The deadline to register to attend is Nov 7, 2021 or when the meeting reaches capacity.
A preliminary meeting agenda will be posted in late-October.
Reasonable Accommodations Information: If you require reasonable accommodations (e.g., captioning, American Sign Language interpreters, Cued Language Transliterators) to participate in this meeting, please contact both Avanti Shirke (email@example.com) AND Dahnish Shams (firstname.lastname@example.org).
The IRIS Program will be holding this meeting only by webinar and not in-person. You will need to register to attend the webinar by visiting the link (in the registration link box). You may also register to give verbal comments at the meeting from this form.
Commenters are given up to 5 minutes to speak. Registration to attend and provide oral comment is open until Oct 25th, and registration to attend is open until Nov 7th or until the 250 person limit is reached - whichever occurs first.
Teleconference/webinar information will be provided a few days before the meeting/webinar is held.
To keep you informed regarding the IRIS Program updates, all attendees who register for this event will also be added to the IRIS Mailing List. If you decide that you do not want to receive these updates, you can unsubscribe from the mailing list at any time.
Note on registering: while you are not required to provide us with any personally identifying information (such as your email address, phone number, etc.), doing so will allow us to process your registration and provide you with the information regarding participation procedures. Failure to provide this information may hinder your ability to participate in this public event.
Once you are registered to participate remotely by webinar you will need:
- A computer with an internet connection. Adobe Flash is required.
- A speaker/headphones or telephone. Audio will be available through the webinar, and also through a teleconference line if you wish to listen by phone or want to make a comment.
- The webinar URL and teleconference details will be e-mailed to registered participants of this meeting.
The webinar room will be opened 30 minutes prior to the workshop for testing and set up. The teleconference line will be opened 10 minutes before the start of the workshop.
Questions: If you are having technical issues in the webinar, you can use the chat window to address the meeting host. If you have a question for the speaker you must use the "ask a question" box to notify the meeting facilitator that you have a question. Once an opportunity is available your question will be addressed.
For any additional questions, please email Dahnish Shams at email@example.com.
Naphthalene Key Science Topics and Materials
Naphthalene Assessment Managers: Erin Yost & Ingrid Druwe
- IRIS Assessment Plan (IAP) for Naphthalene
- Primary Literature Search References Sorted by Author (Naphthalene)(dynamic literature link - generated by HERO)
Key Science Topics
What is an IRIS Assessment Plan? An IRIS Assessment Plan (IAP) communicates to the public the plan for assessing each individual chemical and includes summary information on the IRIS Program’s scoping and initial problem formulation; objectives and specific aims for the assessment; the PECO (Populations, Exposures, Comparators, and Outcomes) criteria that outlines the evidence considered most pertinent to the assessment; and identification of key areas of scientific complexity.
The IRIS Program is seeking a discussion with the public aimed at improving or clarifying the IAP. Below are questions to facilitate the discussion of these science topic:
Topic 1. Species differences in toxicokinetics
The IRIS program is seeking discussion on species differences associated with exposure to naphthalene. Background information is provided below.
Differences in metabolism: Naphthalene is known to be converted to a reactive intermediate(s) through cytochrome P450 (CYP)-dependent metabolism, primarily the CYPF subfamily. While much progress has been made in the characterization of mouse CYP2F2, the CYP thought to be primarily involved in naphthalene metabolism in mice, characterizing the relative contribution of P450 oxidizing enzymes to naphthalene metabolism in rats and humans has been more difficult (Buckpitt et al., 2002; Shultz et al., 1999). The results available at present indicate that there are likely major interspecies catalytic differences between mouse, rat and human CYPF enzyme homologs.
Health effects: The rate and extent of metabolism of naphthalene in various tissues and in different animal species along with anatomical differences in the nasal turbinates between species will be important considerations in evaluating region-specific differences in the production of reactive metabolites across species.
PBPK: Evaluation of the current and available naphthalene PBPK models for reliable route-to-route, interspecies, and/or intraspecies extrapolation is needed. If necessary, further development of PBPK models will also be considered.
Topic 2. Mode of action for carcinogenicity
The IRIS program is seeking discussion on possible modes of action associated with exposure to naphthalene. Background information is provided below.
Multiple animal and in vitro studies published since the 1998 IRIS Toxicological Review have provided mechanistic information and postulated the involvement of several biological processes in the development of naphthalene-induced tumor formation. These proposed processes include genotoxicity, cytotoxicity, and sustained regenerative cell proliferation. Among the key events identified by these studies are the depletion of glutathione and the formation of reactive naphthalene quinone metabolites via the cytochrome P450 pathway. The role and biological plausibility of each of these proposed mechanisms occurring in humans and their role in the formation of naphthalene-induced tumors will need to be evaluated. Differences in enzyme activities between human and rodent tissues exist; therefore, evaluation of the cancer MOA in the context of toxic metabolite formation and the relevance of these toxic metabolites to human cancer hazard will also need to be evaluated.