[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]
-----------------------------------------------------------------------
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.
-----------------------------------------------------------------------
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: bushman.daniel@epamail.epa.gov,
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="">-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/m3) 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/m3 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/m3 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/m3 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/m3 group. The data
obtained in this chronic inhalation study identifies a no-observed-
adverse-effect-level (NOAEL) of 0.2 mg/m3 (duration-adjusted
concentration = 0.036 mg/m3) and a lowest-observed-adverse-effect-
level (LOAEL) of 1.0 mg/m3 (duration-adjusted concentration = 0.18
mg/m3) 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/m3 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="">3 dosed group, and less severe symptoms occurred in the
8 mg/m3 dosed group. A dose related increase in lung weight was
noted in the 8 and 12 mg/m3 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/m3 groups. There was a significant increase
in macrophages in the lungs and lymph nodes of all exposed animals (4
mg/m3 or higher) compared with control groups. This study
demonstrated adverse effects in the lungs and nasal cavity at levels of
4 mg/m3 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/m3 and the
NOAEL of 0.2 mg/m3 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
