Meeting Objective:
The objective of this public meeting was to obtain input from the scientific community and the public on the problem formulation materials which frame the specific scientific questions for the systematic reviews that will be conducted in the assessments of ethylbenzene and napththalene. Specifically, EPA was seeking input on the list of potential health hazards identified by the preliminary literature surveys, the availability of new studies, the hazard questions for systematic review, and a public discussion of key science questions that will be addressed in the assessments. Participants interested in being discussants should register on the EPA website and are also invited to suggest additional science topics by sending an e-mail to EPA_IRIS@icfi.com.
Date:
The meeting was held on September 3 , 2014 from 9:00am - 5:30 pm Eastern Time.
Location:
The live meeting was held at the EPA Conference Center at 2777 South Crystal Drive, Arlington, Virginia 22202. The meeting was also streamed by webinar/teleconference for remote participants. The meeting was not recorded.
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Meeting Agenda:
On September 3, 2014, EPA hosted a public meeting/webinar in Arlington, VA, to provide an opportunity for the public to give input and participate in an open discussion regarding several IRIS chemical assessments that are under development. See the final agenda:
Scoping and Problem Formulation Materials
EPA released scoping and problem formulation materials for new IRIS assessments of ethylbenzene and naphthalene for public comment and discussion. The scoping information was based on input from EPA's program and regional offices and was provided for informational purposes.
During problem formulation, the IRIS Program was looking for input from the scientific community and the general public as it frames the specific scientific questions for the systematic reviews that it will conduct to develop the assessments. These problem formulation materials are the first to be developed since the NRC released its Review of EPA's IRIS Process in May 2014. EPA followed these recommendations in developing the ethylbenzene and naphthalene problem formulations materials. Background information on the chemicals was also provided.
In order to facilitate a scientific discussion, EPA identified several key science questions that were a main focus of the meeting discussion.
Ethylbenzene: Paul Reinhart and George Woodall, Assessment Managers
Key science questions:
Science Question 1: Health outcomes. The preliminary literature survey identified several health outcomes for systematic review (see section3.3). Have any potential health outcomes been missed? Are there inter-relationships between some health outcomes that would warrant their being examined together?
Science Question 2 : Toxicokinetics. The assessment will evaluate and perhaps further develop toxicokinetic models for interspecies extrapolation and route extrapolation (see section 3.4). What key features specific to the kinetics of ethylbenzene would increase the utility of a model?
Science Question 3 : Mode-of-action for mouse lung tumors. In January 2014 an EPA workshop discussed key issues related to the human relevance of lung tumors induced in mice by ethylbenzene, naphthalene, or styrene (see section 3.4). Are there newer data or additional perspectives that would be useful in understanding (1) the role of CYP450 enzymes in the metabolism of ethylbenzene, (2) the contribution of ethylbenzene metabolites to the induction of lung tumors in mice, and (3) the respective roles of genotoxicity and of cytotoxicity and regenerative cell proliferation in the induction of lung tumors in mice?
Science Question 4 : Mode-of-action for rat kidney tumors. Hard (2002) concluded that ethylbenzene-induced renal tubule tumors in rats are related to chemically-induced exacerbation of chronic progressive neuropathy; on the other hand, Seely et al (2002) concluded that this association is marginal (see section 3.4 for references). What data would be useful in resolving this issue?
Science Question 5 : Data gaps, new studies, and research in progress. If you are aware of ongoing, original research that will be published after June 2014, we encourage you to contact us so that we can allocate time on the agenda for one investigator from each research group to discuss the design and, if available, the study results. Members of the public will also be encouraged to register to participate in the subsequent discussion.
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Naphthalene: Channa Keshava, Assessment Manager
Key science questions:
Science Question 1: Health outcomes. The preliminary literature survey identified several health outcomes for systematic review (see section3.3). Have any potential health outcomes been missed? Are there inter-relationships between some health outcomes that would warrant their being examined together?
Science Question 2 : Toxicokinetics. The assessment will evaluate and perhaps further develop toxicokinetic models for interspecies extrapolation and route extrapolation (see section 3.4). What key features specific to the kinetics of naphthalene would increase the utility of a model?
Science Question 3 : Mode-of-action for mouse lung tumors. In January 2014 an EPA workshop discussed key issues related to the human relevance of lung tumors induced in mice by ethylbenzene, naphthalene, or styrene (see section 3.4). Are there newer data or additional perspectives that would be useful in understanding (1) the role of CYP450 enzymes in the metabolism of naphthalene, (2) the contribution of naphthalene metabolites to the induction of lung tumors in mice, and (3) the respective roles of genotoxicity and of cytotoxicity and regenerative cell proliferation in the induction of lung tumors in mice?
Science Question 4 : Mode-of-action for rat nasal tumors. Naphthalene has been associated with the induction of nasal cavity tumors in rats (see section 3.4). What data would be useful in developing hypothesized mode(s)-of-action for this tumor?
Science Question 5: Analysis of toxicogenomics data in this assessment. Toxicogenomics data for naphthalene are available and might be informative for evaluating species and sex differences (see section 3.4). We are interested in hearing a variety of ideas on how to analyze these data.
Science Question 6 : Susceptibility factors. Several reviews have discussed deficiency in the enzyme G6-PD as a potential susceptibility factor for the toxic effects of naphthalene. It also has been noted that hematologic effects of naphthalene are more frequently seen in infants (see section 3.4). We are interested in hearing a variety of ideas on how to analyze these data.
Science Question 7 : Data gaps, new studies, and research in progress. If you are aware of ongoing, original research that will be published after June 2014, we encourage you to contact us so that we can allocate time on the agenda for one investigator from each research group to discuss the design and, if available, the study results. Members of the public will also be encouraged to register to participate in the subsequent discussion.
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