CASRN 91-20-3

IRIS Assessment Plan for Naphthalene (Scoping and Problem Formulation Materials)


[UPDATE] EPA has announced that the August 23, 2018 IRIS Public Science Meeting is postponed until the IRIS Program identifies suitable public science meeting dates in the near future. Stakeholders wishing to provide written comments to the IRIS Program may continue to do so through the docket on until September 5, 2018.


In July 2018, EPA released the IRIS Assessment Plan (IAP) for Naphthalene for public review and comment. 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 PECO provides the framework for developing literature search strategies and inclusion/exclusion criteria, particularly with respect to evidence stream (i.e., human, animal, mechanistic), exposure measures and outcome measures.


U.S. EPA. IRIS Assessment Plan for Naphthalene (Scoping and Problem Formulation Materials). U.S. Environmental Protection Agency, Washington, DC, EPA/635/R-18/007, 2018.


Erin Yost,  Ph:  919-541-0000,  Email:

Ingrid Druwe,  Ph:  919-541-2452,  Email:

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Naphthalene (CAS no. 91-20-3) is a bicyclic aromatic hydrocarbon with the chemical formula C10H8 and a molecular weight of 128.16. Pure naphthalene is a white, water-insoluble solid at room temperature with a vapor pressure of 0.087 mmHg (U.S. EPA, 1987; ATSDR,1993). Naphthalene is produced by distillation and fractionation of either petroleum or coal tar.

Naphthalene’s principal use is as an intermediate in the production of phthalic anhydride. Phthalic anhydride is important in the manufacturing of phthalate plasticizers, resins, dyes as well as insect and animal repellents. Naphthalene is also used in the manufacture of synthetic leather tanning agents and the insecticide carbaryl. Naphthalene has been used as a moth repellent and as a deodorizer for diaper pails and toilets (ATSDR, 1993; U.S. EPA, 1980, 1987).


Date Description
Jul 2018EPA released the IRIS Assessment Plan of Naphthalene (Scoping and Problem Formulation) for a 30-day public comment period. An August 23, 2018 IRIS Public Science Webinar to discuss the document was also announced. [Federal Register Notice Jul 5, 2018]
Jul 2014EPA released the IRIS Toxicological Review of Naphthalene (Scoping and Problem Formulation Materials) for discussion at a public science meeting held on September 3-4, 2014 to provide the opportunity for the public to give input on the developing draft assessment.
Aug 2005EPA released the document Research Needs Related to Naphthalene Assessment summary report from the workshop.
Apr 2005EPA hosted a Peer Consultation Workshop on research needs related to the mode of action of inhalation carcinogenicity on April 7, 2005.
Jul 2004EPA released a revised IRIS Summary and Toxicological Review of Naphthalene (External Review Draft) for public comment and hosted an peer review panel meeting.
Aug 1998EPA revised the IRIS Summary and Toxicological Review of Naphthalene and released an external review draft for public comment.


The IRIS Program will use the IAP to inform the subsequent development of a chemical-specific systematic review protocol.

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