Skip to Content

Proposed Rule

Petition to Remove 4,4′-Methylene Diphenyl Diisocyanate From the List of Hazardous Air Pollutants

Document Details

Information about this document as published in the Federal Register.

Published Document

This document has been published in the Federal Register. Use the PDF linked in the document sidebar for the official electronic format.

Start Preamble


Environmental Protection Agency (EPA).


Notice of receipt of a complete petition to delist 4,4′-methylene diphenyl diisocyanate from the list of hazardous air pollutants.


The EPA is announcing the receipt of a complete petition from the Diisocyanates Panel of the American Chemistry Council (ACC) requesting EPA to remove the chemical 4,4′-methylene diphenyl diisocyanate (MDI)(Chemical Abstract Service No. 101-68-8) from the list of hazardous air pollutants (HAP) contained in section 112(b)(1) of the Clean Air Act (CAA). We have determined that the ACC's original petition dated December 23, 2002, and the addenda provided by the ACC through March 7, 2005, will support an assessment of the human health impacts associated with people living in the vicinity of facilities emitting MDI. In addition, the data submitted by the ACC will support an assessment of the environmental impacts associated with emissions of MDI to the ambient air and deposited onto soil or water. Consequently, we have concluded that ACC's petition is complete as of March 7, 2005, the date that the last addendum was received, and is ready for public comment and the technical review phase of our delisting procedure.

The EPA invites the public to comment on the petition and to provide additional data, beyond that filed in the petition, on sources, emissions, exposure, health effects and environmental impacts associated with MDI that may be relevant to our technical review. The petition is available through Docket ID OAR-2005-0085.


Written comments must be received on or before June 27, 2005.


Submit your comments, identified by Docket ID OAR-2005-0085, by one of the following methods:

  • Federal eRulemaking Portal: Follow the on-line instructions for submitting comments.
  • Agency Web site:​edocket. EDOCKET, EPA's electronic public docket and comment system, is EPA's preferred method for receiving comments. Follow the on-line instructions for submitting comments.
  • Mail: Air and Radiation Docket and Information Center (Mail Code 6102T), Room B108, 1200 Pennsylvania Ave., NW., Washington, DC 20460].
  • Hand Delivery: Air and Radiation Docket and Information Center (Mail Code 6102T), Room B102, U.S. EPA, 1301 Constitution Avenue, NW., Washington, DC 20460. Such deliveries are only accepted during the Docket's normal hours of operation, and special arrangements should be made for deliveries of boxed information.

Instructions: Direct your comments to Docket ID No. OAR-2005-0085. The EPA's policy is that all comments received will be included in the public docket without change and may be made available online at​edocket, including any personal information provided, unless the comment includes information claimed to be Confidential Business Information (CBI) or other information whose disclosure is restricted by statute. Do not submit information that you consider to be CBI or otherwise protected through EDOCKET,, or e-mail. The EPA EDOCKET and the Federal Web sites are “anonymous access” systems, which means EPA will not know your identity or contact information unless you provide it in the body of your comment. If you send an e-mail comment directly to EPA without going through EDOCKET or, your e-mail address will be automatically captured and included as part of the comment that is placed in the public docket and made available on the Internet. If you submit an electronic comment, EPA recommends that you include your name and other contact information in the body of your comment and with any disk or CD-ROM you submit. If EPA cannot read your comment due to technical difficulties and cannot contact you for clarification, EPA may not be able to consider your comment. Electronic files should avoid the use of special characters, any form of encryption, and be free of any defects or viruses. For additional instructions on submitting comments, go to the SUPPLEMENTARY INFORMATION section of this document.

Docket: All documents in the docket are listed in the EDOCKET index at​edocket. Although listed in the index, some information is not publicly available, i.e., CBI or other information whose disclosure is restricted by statute. Certain other information, such as copyrighted material, is not placed on the Internet Start Printed Page 30408and will be publicly available only in hard copy form. Publicly available docket materials are available either electronically in EDOCKET or in hard copy form at the Air and Radiation Docket, Docket ID No. 2005-0085, EPA/DC, EPA West, Room B102, 1301 Constitution Ave., NW., Washington, DC. The Public Reading Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the Air and Radiation Docket is (202) 566-1742.

Start Further Info


Dr. Scott Jenkins, Office of Air Quality Planning and Standards, Emission Standards Division (Mailcode C404-01), EPA, Research Triangle Park, NC 27711; telephone number: (919) 541-1167; fax number: (919) 541-0840; e-mail address:

End Further Info End Preamble Start Supplemental Information


I. General Information

A. What Should I Consider as I Prepare My Comments for EPA?

1. Submitting CBI. Do not submit this information to EPA through EDOCKET, or e-mail. Clearly mark the part or all of the information that you claim to be CBI. For CBI information in a disk or CD ROM that you mail to EPA, mark the outside of the disk or CD ROM as CBI and then identify electronically within the disk or CD ROM the specific information that is claimed as CBI. In addition to one complete version of the comment that includes information claimed as CBI, a copy of the comment that does not contain the information claimed as CBI must be submitted for inclusion in the public docket. Information so marked will not be disclosed except in accordance with procedures set forth in 40 CFR part 2.

2. Tips for Preparing Your Comments. When submitting comments, remember to:

  • Identify the rulemaking by docket number and other identifying information (subject heading, Federal Register date and page number).
  • Follow directions—The Agency may ask you to respond to specific questions or organize comments by referencing a Code of Federal Regulations (CFR) part or section number.
  • Explain why you agree or disagree; suggest alternatives and substitute language for your requested changes.
  • Describe any assumptions and provide any technical information and/or data that you used.
  • If you estimate potential costs or burdens, explain how you arrived at your estimate in sufficient detail to allow for it to be reproduced.
  • Provide specific examples to illustrate your concerns, and suggest alternatives.
  • Explain your views as clearly as possible, avoiding the use of profanity or personal threats.
  • Make sure to submit your comments by the comment period deadline identified.

II. Petitions To Delist a Hazardous Air Pollutant

A. What Is the List of Hazardous Air Pollutants?

The list of HAP includes a wide variety of organic and inorganic substances released from large and small industrial operations, fossil fuel combustion, gasoline and diesel-powered vehicles, and many other sources. The HAP have been associated with a wide variety of adverse health effects, including cancer, neurological effects, reproductive effects, and developmental effects. The health effects associated with the various HAP may differ depending upon the toxicity of the individual HAP and the particular circumstances of exposure, such as the amount of chemical present, the length of time a person is exposed, and the stage in life of the person when the exposure occurs. The list of HAP, which includes MDI, can be found in section 112(b)(1) of the CAA. The HAP list provides the basis for research, regulation, and other related EPA activities under the CAA.

B. What Is a Delisting Petition?

A delisting petition is a formal request to EPA from an individual or group to remove a specific HAP from the HAP list. The removal of a HAP from the list eliminates it from consideration in EPA's program to promulgate national, technology-based emissions control standards. This technology-based standards program is commonly referred to as the maximum achievable control technology (MACT) program.

Petitions to add or delete chemicals from the HAP list are allowed under section 112(b)(3)(A) of the CAA. The CAA specifies that any person may petition the Administrator to modify, by addition or deletion, the list of HAP. The EPA Administrator is required under section 112(b)(3)(A) of the CAA to either grant or deny a petition to delist a specific HAP within 18 months of the receipt of a complete petition.

To delete a substance from the HAP list, CAA section 112(b)(3)(C) requires that the petitioner must provide adequate data on the health and environmental effects of the substance to determine that emissions, ambient concentrations, bio-accumulation or deposition of the substance may not reasonably be anticipated to cause any adverse effects to human health or adverse environmental effects.

C. How Does EPA Review a Petition To Delist a HAP?

The petition review process proceeds in two phases: A completeness determination and a technical review. During the completeness determination, we conduct a broad review of the petition to determine whether all of the necessary subject areas are addressed. In addition, we determine if adequate data, analyses, and evaluation are included for each subject area. Once the petition is determined to be complete, we place a notice of receipt of a complete petition in the Federal Register. That notice announces a public comment period on the petition and starts the technical review phase of our decision-making process. The technical review determines whether the petition has satisfied the necessary requirements and can support a decision to delist the HAP. All comments and data submitted during the public comment period are considered during the technical review.

D. How Is the Decision To Delist a HAP Made?

The decision to either grant or deny a petition is made after a comprehensive technical review of both the petition and the information received from the public to determine whether the petition satisfies the requirements of section 112(b)(3)(C) of the CAA. If the Administrator decides to grant a petition, a proposal will be published in the Federal Register announcing that decision and the opportunity for public comment. That notice would propose a modification of the HAP list and present the reasoning for doing so. However, if the Administrator decides to deny a petition, a notice setting forth an explanation of the reasons for denial will be published instead. A notice of denial constitutes final Agency action of nationwide scope and applicability and is subject to judicial review as provided in section 307(b) of the CAA.

III. Completeness Determination and Request for Public Comment

On December 23, 2002, we received a petition from the ACC's Diisocyanates Panel to remove MDI from the HAP list. Because of incomplete documentation of emissions information and modeling procedures, EPA determined that the Start Printed Page 30409petition was incomplete and requested that the petitioner provide additional information. The petitioner submitted an addendum on September 2, 2004, addressing EPA's concerns regarding the completeness of the petition. We identified a need for additional information supporting the MDI emissions estimates and the modeling performed. The petitioner submitted a second addendum dated February 28, 2005, to address these issues. We received one of the appendices to this addendum, in the form of a CD-ROM, on March 7, 2005.

After reviewing the original petition and the addenda, we have determined that all of the necessary subject areas for a human health and environmental risk assessment have been addressed. Therefore, the petition is complete and ready for technical review. The ACC's last submission, received March 7, 2005, marked the start of the 18-month technical review and decision period. Today's notice initiates our comprehensive technical review of the petition and invites public comment on the substance of the petition as described above.

IV. Description of Petition

The original petition and addenda provided by the ACC contain the following information:

  • Background data on MDI including chemical properties, physical properties, production data, and use data;
  • Identification and location of facilities that emit MDI;
  • Estimated emission rates of MDI for each facility;
  • Toxicological data describing the human health and environmental effects of MDI;
  • Atmospheric dispersion modeling that provide estimates of MDI concentrations adjacent to facilities that emit it;
  • Environmental effects data characterizing the fate of MDI emitted to the atmosphere; and
  • Characterization of risks to human health and the environment due to emissions of MDI.

The petitioners revised the estimates of MDI emissions contained in the 1996 National Emissions Inventory (NEI) using a method described by William Robert and colleagues in the article titled, “Developing a National Emissions Inventory for MDI,” (Environmental Manager, October, 2001). Many of these changes were incorporated into the 1999 NEI. The petitioners have continued to revise emissions estimates for MDI since the 1999 NEI. The petition presents their revised MDI emissions inventory which, according to the petitioners, represents an improvement over the 1999 NEI. These revisions resulted in a 400 percent increase in the number of facilities that emit MDI and a 75 percent decrease in national MDI emissions.

Based on the chemical and physical properties of MDI, the petitioner claims that inhalation is the only significant route of human exposure to MDI emissions. Using their revised MDI emissions inventory and some site-specific data as input for air dispersion modeling, the petition develops estimates of the maximum annual and 24-hour concentrations anticipated to occur at the boundaries of facilities that emit MDI. The petition compares modeling output to available health data and concludes that, given the low concentrations anticipated to occur at facility boundaries, MDI emissions cannot reasonably be anticipated to cause chronic or acute adverse health impacts in people living near MEI-emitting facilities.

The petition also claims that MDI is not expected to adversely impact the environment. Work supporting MDI's low environmental toxicity, lack of environmental persistence, and its low potential for bioaccumulation is presented.

We invite the public to comment on the technical merits of this petition and to submit any information that may impact EPA's ultimate decision to grant or deny the petitioner's request.

Start Signature

Dated: May 18, 2005.

Robert Brenner,

Acting Assistant Administrator for Air and Radiation.

End Signature End Supplemental Information

[FR Doc. 05-10579 Filed 5-25-05; 8:45 am]