[Federal Register Volume 62, Number 43 (Wednesday, March 5, 1997)]
[Proposed Rules]
[Pages 10006-10009]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-5307]


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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 372

[OPPTS-400101; FRL-5584-9]
RIN 2070-AC00


Polymeric Diphenylmethane Diisocyanate; Toxic Chemical Release 
Reporting; Community Right-to-Know

AGENCY: Environmental Protection Agency (EPA).

ACTION: Denial of petition.

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SUMMARY: EPA is denying a petition to remove polymeric diphenylmethane 
diisocyanate (PMDI) from the diisocyanates category subject to the 
reporting requirements under section 313 of the Emergency Planning and 
Community Right-to-Know Act of 1986 (EPCRA) and section 6607 of the 
Pollution Prevention Act of 1990 (PPA). EPA has reviewed the available 
toxicological data on this chemical and has determined that PMDI does 
not meet the section 313(d)(3) deletion criterion. Therefore, EPA is 
denying the petitioner's request to remove PMDI from the EPCRA section 
313 diisocyanates category.

FOR FURTHER INFORMATION CONTACT: Daniel R. Bushman, Acting Petitions 
Coordinator, 202-260-3882, or e-mail: <a href="/cdn-cgi/l/email-protection#3c5e494f54515d5212585d525559507c594c5d515d555012594c5d125b534a"><span class="__cf_email__" data-cfemail="ec8e999f84818d82c2888d82858980ac899c8d818d8580c2899c8dc28b839a">[email protected]</span></a>, 
for specific information regarding this document or for more 
information on EPCRA section 313, the Emergency Planning and Community 
Right-to-Know Hotline, Environmental Protection Agency, Mail Code 5101, 
401 M St., SW., Washington, DC 20460, Toll free: 1-800-535-0202, in 
Virginia and Alaska: 703-412-9877 or Toll free TDD: 1-800-553-7672.

SUPPLEMENTARY INFORMATION:

I. Introduction

A. Statutory Authority

    This action is taken under sections 313(d) and (e)(1) of the 
Emergency Planning and Community Right-to-Know Act of 1986 (EPCRA), 42 
U.S.C. 11023. EPCRA is also referred to as Title III of the Superfund 
Amendments and Reauthorization Act of 1986 (SARA) (Pub. L. 99-499).

B. Background

    Section 313 of EPCRA requires certain facilities manufacturing, 
processing, or otherwise using listed toxic chemicals to report their 
environmental releases of such chemicals annually. Beginning with the 
1991 reporting year, such facilities also must report pollution 
prevention and recycling data for such chemicals, pursuant to section 
6607 of the Pollution Prevention Act of 1990 (PPA), 42 U.S.C. 13106. 
Section 313 established an initial list of toxic chemicals that was 
comprised of more than 300 chemicals and 20 chemical categories. 
Polymeric diphenylmethane diisocyanate (PMDI) is a diisocyanate 
chemical reportable under the diisocyanates category which was added to 
the EPCRA section 313 list of toxic chemicals on November 30, 1994 (59 
FR 61432) (FRL-4922-2). Section 313(d) authorizes EPA to add or delete 
chemicals from the list, and sets forth criteria for these actions. EPA 
has added and deleted chemicals from the original statutory list. Under 
section 313(e)(1), any person may petition EPA to add chemicals to or 
delete chemicals from the list. Pursuant to EPCRA section 313(e)(1), 
EPA must respond to petitions within 180 days, either by initiating a 
rulemaking or by publishing an explanation of why the petition is 
denied.
    EPCRA section 313(d)(2) states that a chemical may be listed if any 
of the listing criteria are met. Therefore, in order to add a chemical, 
EPA must demonstrate that at least one criterion is met, but does not 
need to examine whether all other criteria are also met. Conversely, in 
order to remove a chemical from the list, EPA must demonstrate that 
none of the criteria are met.
    EPA issued a statement of petition policy and guidance in the 
Federal Register of February 4, 1987 (52 FR 3479), to provide guidance 
regarding the recommended content and format for submitting petitions. 
On May 23, 1991 (56 FR 23703), EPA issued guidance regarding the 
recommended content of petitions to delete individual members of the 
section 313 metal compound categories. EPA has also published a 
statement clarifying its interpretation of the section 313(d)(2) and 
(3) criteria for adding and deleting chemical substances from the 
section 313 list (59 FR 61432).

II. Description of Petition

    On August 15, 1995, EPA received a petition from the Polyurethane 
Division of the Society of the Plastics Industry (SPI) to delete PMDI 
(Chemical Abstracts Service Registry Number (CASRN) 9016-87-9) from the 
list of chemicals reportable under EPCRA section 313 and PPA section 
6607. Specifically, the petitioner requested that PMDI be removed from 
the EPCRA section 313 diisocyanates category. The petitioner contends 
that PMDI should be delisted because: (1) PMDI does not independently 
meet the EPCRA section 313 toxicity criteria since it is a mixture that 
contains approximately 50 percent 4,4'-methylenediphenylene isocyanate 
(MDI), and it is the MDI that dominates the toxicity of the mixture; 
(2) PMDI is not a diisocyanate and does not meet the molecular weight 
criterion of the diisocyanates category that the petitioner claims was 
set by EPA; (3) MDI, which is the constituent of toxic concern, is 
listed in the diisocyanates category and its releases would continue to 
be reported by users of PMDI; and (4) the higher molecular weight 
oligomers that make up the other 50 percent of PMDI have low volatility 
relative to other members of the diisocyanates category which prevents 
significant environmental exposures.
    Because the petitioner does not dispute the listing of MDI and 
acknowledges that the MDI component of PMDI is a source of the toxicity 
of PMDI, this petition is limited to the issue of whether the higher 
molecular weight oligomers in PMDI can reasonably be anticipated to add 
to the toxicity of PMDI such that PMDI should be included as a separate 
chemical in the diisocyanates category.

III. EPA's Technical Review of PMDI

A. Introduction

    On November 30, 1994 (59 FR 61432), EPA added the diisocyanates 
category to the EPCRA section 313 list of toxic chemicals based on 
concerns for chronic pulmonary toxicity. There are no other criteria 
for defining this EPCRA section 313 category. The diisocyanates 
category consists of a list of 20 individual diisocyanates, including 
PMDI. The reference that the petitioner makes to a ``molecular weight 
criteria set by EPA for the diisocyanates category'' refers to the 
definition EPA set for the diisocyanates category under review by EPA's 
Office of Pollution Prevention and Toxics (OPPT) in the existing 
chemicals program (Ref. 1). The OPPT existing chemicals review was 
undertaken to determine whether to regulate diisocyanates under the 
Toxic Substances Control Act (TSCA). The TSCA diisocyanates category 
was defined as ``monomeric diisocyanates of molecular weight less than 
or equal to 300, plus polymeric diphenylmethane diisocyanate (which is 
only 40 to 60 percent polymerized).'' While EPA included all members of 
the TSCA category in the EPCRA section 313 diisocyanates category, it 
did not

[[Page 10007]]

include any molecular weight criterion or any other criteria other than 
the list of chemicals included in the EPCRA category. Therefore, 
molecular weight alone does not exclude a diisocyanate from being 
included in the EPCRA section 313 diisocyanates category.
    The technical review of the petition to delete polymeric 
diphenylmethane diisocyanate included a review of the chemistry of PMDI 
(Refs. 2 and 3) and available toxicological data (Refs. 3-16). The 
focus of EPA's review, however, was on whether the higher molecular 
weight oligomers in PMDI can reasonably be anticipated to cause chronic 
pulmonary toxicity.

B. Chemistry

    PMDI is manufactured by a process that results in a mixture that 
contains approximately 50 percent MDI and 50 percent higher molecular 
weight oligomers (Refs. 2 and 3). PMDI typically contains the following 
products in the percent ranges indicated in the figure below:
[GRAPHIC] [TIFF OMITTED] TP05MR97.015


                                                                                                                
                                                                                                                
                                           n                  MW               Weight %                         
                                                                                                                
                                        0 (MDI)               250                40-60                          
                                           1                  381                25-35                          
                                           2                  512                10-20                          
                                           3                  643                 <5                            
                                           4                  774                trace                          
                                                                                                                

The higher molecular weight oligomers are those where n = 1 or greater 
in the above figure. As indicated above, less than 5 percent of the 
compounds in the mixture have a molecular weight greater than 512. The 
higher molecular weight oligomers contain the diisocyanate moiety; 
however, they are not formally identified as diisocyanates since they 
have more than two isocyanate groups. Since the reactive sites in 
diisocyanates are the isocyanate groups, these extra isocyanate groups 
are additional reactive sites (both chemically and biologically) within 
the molecule (Ref. 4). These higher molecular weight oligomers are 
structurally very similar to MDI, varying only by the sequential 
addition of an aromatic ring and an isocyanate group.
    Since the higher molecular weight oligomers are never isolated as 
pure compounds, their physical/chemical properties have not been 
measured and must be estimated. Using data on MDI as a reference point, 
the estimated melting point range for the higher molecular weight 
oligomers in PMDI would be 30-50  deg.C, the estimated boiling point 
would be > 400  deg.C and the estimated vapor pressure would be < 1 x 
10<SUP>-5 millimeters mercury (mm Hg) (Ref. 2).

C. Toxicity Evaluation

    In a 2-year chronic inhalation study (Refs. 12 and 13), Wistar rats 
(60/sex/exposure level) were exposed whole-body to 0, 0.2, 1.0, and 6.0 
milligrams per cubic meter (mg/m<SUP>3) of PMDI aerosol for 6 hours/day 
(hrs/day), 5 days/week (days/wk), for 24 months. The PMDI material 
tested was a dark brown liquid with an average molecular weight of 
about 400 that contained 47 percent MDI and 53 percent higher molecular 
weight oligomers. Ninety five percent of the particles in the aerosols 
generated were smaller than 5 micrometers.
    There were no treatment-related deaths, changes in body weights, 
clinical signs or effects on serum chemistry, hematology or urinalysis 
parameters. There was a significant increase in lung weights in both 
males and females exposed to 6.0 mg/m<SUP>3 after 1 and 2 years. In the 
2-year study, males exposed to the highest dose had increased incidence 
of spotted and discolored lungs. At the interim sacrifices at 1 year, 
males and females in the highest dose group had treatment related 
histological changes in the nasal cavity, lungs and mediastinal lymph 
nodes. The incidence and severity of degeneration and basal cell 
hyperplasia of the olfactory epithelium and Bowman's gland hyperplasia 
were increased in males of the 1.0 and 6.0 mg/m<SUP>3 groups and in 
females of the high dose group following the 2 year exposure period. 
The lungs from the rats of the 1.0 and 6.0 mg/m<SUP>3 group had similar 
changes to, but more severe than, those found after 1 year of exposure. 
There were significant increases in alveolar duct epithelialization, 
accumulation of macrophages containing PMDI associated yellow pigment 
and focal fibrosis in males and females of the mid and high dose 
groups. Pulmonary adenomas were found in 6 males and 2 females and 1 
male had pulmonary adenocarcinoma in the 6.0 mg/m<SUP>3 group. The data 
obtained in this chronic inhalation study identifies a no-observed-
adverse-effect-level (NOAEL) of 0.2 mg/m<SUP>3 (duration-adjusted 
concentration = 0.036 mg/m<SUP>3) and a lowest-observed-adverse-effect-
level (LOAEL) of 1.0 mg/m<SUP>3 (duration-adjusted concentration = 0.18 
mg/m<SUP>3) based on hyperplasia of the olfactory epithelium.
    In a 90-day inhalation study (Ref. 14), Wistar rats (15/sex/dose) 
were exposed to 4, 8, and 12 mg/m<SUP>3 of PMDI aerosol for 6 hrs/day, 
5 days/wk, for 13 weeks. The content of the PMDI was approximately 52 
percent MDI and 48 percent higher molecular weight oligomers and 95 
percent of the particles in the aerosols had aerodynamic diameters of < 
5 micrometers. Mortality and severe respiratory distress occurred in 
the 12 mg/m<SUP>3 dosed group, and less severe symptoms occurred in the 
8 mg/m<SUP>3 dosed group. A dose related increase in lung weight was 
noted in the 8 and 12 mg/m<SUP>3 dose groups for both males and 
females. Degenerative lesions occurred

[[Page 10008]]

in the olfactory epithelium of the nasal cavity of both males and 
females in the 12 mg/m<SUP>3 groups. There was a significant increase 
in macrophages in the lungs and lymph nodes of all exposed animals (4 
mg/m<SUP>3 or higher) compared with control groups. This study 
demonstrated adverse effects in the lungs and nasal cavity at levels of 
4 mg/m<SUP>3 and above.
    Although there are no toxicological studies available on the higher 
molecular weight oligomers of PMDI in the absence of MDI, there is 
indirect evidence, from studies of diisocyanates other than PMDI, to 
support the conclusion that the higher molecular weight oligomers can 
cause chronic pulmonary toxicity. For some other diisocyanates, the 
higher molecular weight oligomers rather than the monomeric form may 
induce adverse pulmonary effects. In one study (Ref. 15), subjects 
exposed to a prepolymer of toluene diisocyanate (TDI) in wood varnish 
exhibited an asthmatic reaction, but exposure to monomeric TDI did not 
elicit the same response. Another prospective study (Ref. 16), was 
conducted among 10 workers with occupational asthma caused by spray 
paints which contained both monomeric hexamethylene diisocyanate (HDI) 
and polymeric HDI. In the study, four workers developed asthmatic 
reactions only after exposure to polymeric HDI and not after exposure 
to monomeric HDI.
    In the chronic inhalation studies discussed above, the test animals 
where exposed to aerosols of PMDI which should have contained a 
representative sample of all of the components of PMDI. From these 
chronic inhalation studies, it is not possible to separate out the 
adverse health effects caused by MDI from those caused by the higher 
molecular weight oligomers and EPA is aware of no studies on the higher 
molecular weight oligomers themselves. However, given the structural 
similarities between MDI and the higher molecular weight oligomers, it 
is reasonable to anticipate that their toxicological properties will be 
similar to those of MDI and upon exposure will result in the adverse 
health effects observed in the PMDI studies. In addition, the indirect 
evidence discussed above also supports this conclusion.

D. Technical Summary

    The technical review of the petition to delete polymeric 
diphenylmethane diisocyanate from the diisocyanates category focused on 
the chronic toxicity of the higher molecular weight oligomers contained 
in PMDI. Animal studies conducted on aerosolized PMDI have demonstrated 
that PMDI can cause chronic pulmonary toxicity. Because of the 
structural similarities between MDI and the higher molecular weight 
oligomers of PMDI, there is no basis to conclude that the toxicity 
observed in these studies is due only to the MDI present in PMDI. Based 
on a review of the available data on PMDI and other diisocyanates, EPA 
has determined that there is sufficient evidence to reasonably 
anticipate that the higher molecular weight oligomers of PMDI can cause 
chronic pulmonary toxicity.

IV. Rationale for Denial

    EPA is denying the petition submitted by the Polyurethane Division 
of the Society of the Plastics Industry to delete PMDI from the 
diisocyanates category on the EPCRA section 313 list of toxic 
chemicals. This denial is based on EPA's conclusion that, based on 
available data on PMDI and other diisocyanates, the higher molecular 
weight oligomers of PMDI can reasonably be anticipated to cause chronic 
pulmonary toxicity. EPA considers the LOAEL of 1.0 mg/m<SUP>3 and the 
NOAEL of 0.2 mg/m<SUP>3 for PMDI to be relatively low doses and thus 
EPA does not consider PMDI to have low chronic toxicity. Therefore, in 
accordance with EPA's stated policy on the use of exposure assessments 
(59 FR 61432, November 30, 1994), EPA does not believe that an exposure 
assessment is necessary to conclude that PMDI meets the toxicity 
criterion of EPCRA section 313(d)(2)(B).

V. References

    1. USEPA, OPPTS, 1995. Memorandum from Sandra Strassman-Sundy, 
Existing Chemical Assessment Division, re: Additions to Section 313. 
(May 6, 1992).
    2. USEPA, OPPTS, 1995. Chemistry Report for Delisting of Polymeric 
MDI by Diana Darling, Industrial Chemistry Branch, Economics, Exposure 
and Technology Division, Office of Pollution Prevention and Toxics. 
(September 25, 1995).
    3. USEPA, OPPTS, 1995. Memorandum from James W. Holder, Effects 
Identification and Characterization Group, National Center for 
Environmental Assessment, Office of Research and Development, re: 
Response to Delist Polymeric MDI (PMDI) from Ongoing MDI Reporting 
under Section 313, Toxic Chemical Release Reporting of EPCRA (Emergency 
Right-to-Know Act of SARA of 1986). (September 18, 1995).
    4. Dynamac. 1987. Generic Health Hazard Assessment of the Chemical 
Class Diisocyanates, Final Report May 5, 1987, Appendix 4. EPA Contract 
No. 68-02-3990, Work Assignment No. 205. Submitted to USEPA, Office of 
Toxic Substances, Health and Environmental Review Division, Washington, 
DC Prepared by Dynamac Corporation, Rockville, MD.
    5. USEPA, OPPTS, 1995. Memorandum from Nicole Paquette, Health 
Effects Branch, Health and Environmental Review Division, Office of 
Pollution Prevention and Toxics, re: Review of the Delisting Petition 
for Polymeric Diphenylmethane Diisocyanate (PMDI). (September 20, 
1995).
    6. USEPA, OPPTS, 1995. Memorandum from Daniel Bushman, Industrial 
Chemistry Branch, Economics, Exposure and Technology Division, Office 
of Pollution Prevention and Toxics, re: Health Effects Review for 
Polymeric Diphenylmethane Diisocyanate. (October 2, 1995).
    7. USEPA, OPPTS, 1995. Memorandum from Nicole Paquette, Health 
Effects Branch, Health and Environmental Review Division, Office of 
Pollution Prevention and Toxics, re: Health Effects Review for 
Polymeric Diphenylmethane Diisocyanate (PMDI). (October 5, 1995).
    8. USEPA, OPPTS, 1995. Memorandum from Elbert L. Dage, Analysis and 
Information Management Branch, Chemical Screening and Risk Assessment 
Division, Office of Pollution Prevention and Toxics. re: Risk 
Assessment Review for Polymeric Diphenylmethane Diisocyanate (PMDI). 
(November 7, 1995).
    9. USEPA, OPPTS, 1996. Memorandum from Nicole Paquette, Health 
Effects Branch, Health and Environmental Review Division, Office of 
Pollution Prevention and Toxics, re: Health Effects Review for 
Polymeric Diphenylmethane Diisocyanate (PMDI). (January 16, 1996).
    10. USEPA, OPPTS, 1996. Memorandum from Daniel Bushman, Toxics 
Release Inventory Branch, Environmental Assistance Division, re: EPCRA 
Section 313 Petition to Delist PMDI. (July 8, 1996).
    11. USEPA, OPPTS, 1996. Memorandum from Nicole Paquette, Health 
Effects Branch, Health and Environmental Review Division, Office of 
Pollution Prevention and Toxics, re: EPCRA Section 313 Petition to 
Delist Polymeric Diphenylmethane Diisocyanate (PMDI). (July 9, 1996).
    12. Reuzel, P.G.J., Arts, J.H.E., Lomax, L.G., Kuijpers, M.H.M., 
Kuper, C.F., Feron, V.J., Loser, E., ``Chronic Inhalation Toxicity and 
Carcinogenicity Study of Respirable Polymeric

[[Page 10009]]

Methylene Diphenyl Diisocyanate (Polymeric MDI) Aerosol in Rats,'' 
Journal of Fundamental and Applied Toxicology, v. 22, (1994), pp. 195-
210.
    13. Reuzel, P.G.J., Arts, J.H.E., Kuypers, M.H.M., Kuper, C.F., 
``Chronic Toxicity/Carcinogenicity Inhalation Study of Polymeric 
Methylene Diphenyl Diisocyanate Aerosol in Rats (Final Report),'' 
Prepared by Civo Institute for the International Isocyanate Institute. 
Report No. V88.122. (March 1990).
    14. Reuzel, P.G.J., Kuper, C.F., Feron, V.J., Appelman, L.M., 
Loser, E., ``Acute, Subacute, and Subchronic Inhalation Toxicity 
Studies of Respirable Polymeric Methylene Diphenyl Diisocyanate 
(Polymeric MDI) Aerosol in Rats,'' Journal of Fundamental and Applied 
Toxicology, v. 22, (1994), pp. 186-194.
    15. Vandenplas, O., Malo, J.L., Saetta, M., Mapp, C.E., Fabbri, 
L.M., ``Occupational Asthma and Extrinsic Alveolitis Due to 
Isocyanates: Current Status and Perspective,'' British Journal of 
Industrial Medicine, v. 30, (1993), pp. 213-228.
    16. Vandenplas, O., Cartier, A., Lesage, J., Cloutier, Y., 
Perrault, G., Grammar, L.C., Shaughnessy, M.A., Malo, J.L., 
``Prepolymers of Hexamethylene Diisocyanate as a Cause of Occupational 
Asthma,'' Journal of Allergy and Clinical Immunology, v. 91, (1993), 
pp. 850-861.

VI. Administrative Record

    The record supporting this decision is contained in docket control 
number OPPTS-400101. All documents, including the references listed in 
Unit V. of this document and an index of the docket, are available to 
the public in the TSCA Nonconfidential Information Center (NCIC), also 
known as the Public Docket Office, from noon to 4 p.m., Monday through 
Friday, excluding legal holidays. The TSCA NCIC is located at EPA 
Headquarters, Rm. NE-B607, 401 M St., SW., Washington, DC 20460.

List of Subjects in 40 CFR Part 372

    Environmental protection, Community right-to-know, Reporting and 
recordkeeping requirements, and Toxic chemicals.

    Dated: February 20, 1997.
Lynn R. Goldman,
Assistant Administrator for Prevention, Pesticides and Toxic 
Substances.

[FR Doc. 97-5307 Filed 3-4-97; 8:45 am]
BILLING CODE 6560-50-F


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