3074 Tsca Pocketguide POLYMER EXEMPTION

A PracticalUnderstanding

of thePolymer

ExemptionUnder the

ToxicSubstances

Control Act

A Pocket Guidecompliments ofThe Attorneys andScientists of Kellerand Heckman LLP.

Law OfficesWashington, D.C.

Brussels

San Francisco

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KELLER AND HECKMAN LLPServing Business through Law and Science®

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A PracticalUnderstandingof the PolymerExemptionUnder the Toxic SubstancesControl Act

by Justin C. Powell. Esq., Ph.D.September 22, 2003

Note: The content of this publication is based on information believed to be accurate and reliable as of the date of publication. Administrative and judicialinterpretations, as well as the rules themselves, are subject to change. Thispublication is not intended as, and does not constitute, legal advice for particularized facts. Regulatory counsel should be consulted for advice onparticular compliance issues.

Copyright © 2003 Keller and Heckman LLP, 1001 G Street, N.W., Washington, D.C.20001, www.khlaw.com. All Rights Reserved. Reproduction in whole or part is permitted with attribution.

A Practical Understanding of the Polymer Exemption Under TSCA

Introduction ................................................................................................ 1

I. Polymer Exemption Requirements ........................................................ 3A. Paragraph (e) Conditions .................................................................. 3

1. Condition (e)(3) ........................................................................ 32. Condition (e)(1) ........................................................................ 43. Condition (e)(2) ...................................................................... 4

B. Exclusions ........................................................................................ 51. (d)(4); Unreviewed Reactants ...................................................... 52. (d)(1); Positively Charged Polymers ............................................ 63. (d)(2); Atomic Element Limitations ............................................ 64. (d)(3); Instability ........................................................................ 75. (d)(5); High Molecular Weight, Water-Absorbing Polymers .......... 86. Reactive Functional Groups ...................................................... 107. Molecular Weight Less Than 1000 ............................................ 12

C. Polymer Definition.......................................................................... 12

II. The Two-Percent Rule ........................................................................ 13

III. Reporting and Recordkeeping .......................................................... 16A. Reports ............................................................................................ 16B. Records............................................................................................ 16

IV. Summary .............................................................................................. 17

Endnotes .................................................................................................... 19

Table of Contents


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Introduction

In 1984, the Environmental Protection Agency (EPA) published the firstexemption for polymers, which modified the new chemical reporting requirementsof the Toxic Substances Control Act (TSCA) for certain high molecular weightpolymers and certain polyesters. On March 29, 1995, the EPA amended the origi-nal (1984) polymer exemption rule at 40 C.F.R. § 723.250.1/ Polymers that werethe subjects of granted exemption notices under the 1984 polymer exemption, havecontinuing validity so long as they are in compliance with the terms of the originalpolymer exemption. Polymers whose 1984 polymer exemptions were granted maystill be placed on the TSCA Inventory after manufacture or importation for the firsttime. However, no new exemptions under the 1984 rule were accepted after May30, 1995, the effective date of the amended polymer exemption.

While the 1995 polymer exemption is much more complicated than the origi-nal exemption, a much larger percentage of polymers are likely to be eligible thanunder the provisions of the 1984 polymer exemption. Moreover, the currentexemption generally provides greater benefits for polymers that qualify.

The benefits that encourage use of the 1995 exemption more than offset theincreased complexities. The most exceptional feature of the amended exemption isthat one can manufacture or import an eligible new polymer virtually without delay.This is because polymers that are eligible for the exemption are not required toundergo a review by the EPA. In addition, one does not have to satisfy many of theother requirements of premanufacture notification: filing a detailed submission,paying a $2500 user fee, or obtaining a Chemical Abstracts Service name for thepolymer.

Manufacturers and importers must make a determination of eligibility, keepadequate records, and file an end-of-year report in connection with the use of theamended exemption. Not all polymers will qualify. Overall, the polymer exemp-tion significantly reduces the impediments to the commercialization of new polymers, which, in turn, greatly facilitates more rapid introduction of less riskypolymers in commerce.

Unfortunately, it is not usually simple to determine if a given polymer willqualify for the amended exemption. Because the EPA will not make a contempora-neous, independent review, it is essential that businesses correctly interpret theexemption and apply its provisions assiduously. The records that must be keptrequire documentation of the identity of the polymer; certification that the eligibili-ty criteria are met; and support, where needed, that the polymer qualifies for thetype of exemption claimed.

We believe that a potential user of the exemption should begin by definitivelyestablishing the chemical identity and relevant characteristics of the polymer to beconsidered. This cannot be emphasized too strongly. The number of polymers forwhich the exemption is invoked is crucial. If a polymer is not defined well, it can-not be distinguished from another polymer for regulatory purposes, and the

Introduction

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determination of eligibility is on slippery, steep ground. Our advice: polymerswhose identities and relevant characteristics cannot be sufficiently defined shouldbe presumed to be ineligible for the exemption.

Once a polymer is sufficiently defined, its eligibility may be determined. Ifeligible, the new polymer can be manufactured or imported immediately. Whereapplicable, this can be an immense benefit. However, by exempting certain poly-mers from premanufacture review, the EPA has given the responsibility of certifica-tion for this eligibility to individuals in businesses. At first glance, this burden mayseem less than it actually is.

In addition to recordkeeping, a one-time report is required for each polymermanufactured or imported under the exemption. Manufacturers and importers ofthe exempt polymers must report the number of polymers that have been commer-cialized. This can be done for each site of manufacture or import, or this report canbe consolidated into a single report for the manufacturer or importer. Consolidationshould avoid duplicate reports for the same polymers. The EPA must receive thisreport by January 31 of the year following the calendar year in which the polymerswere introduced into commerce under the exemption for the first time. Note thatonly the number of polymers per site or per manufacturer is reportable; the chemi-cal identity of those polymers should not be reported.

Preparing an accurate report will be impossible unless one can validly distin-guish one polymer from another. Such discrimination is difficult because manufac-turers can create polymers with vastly different properties that, under TSCA, theEPA considers the same polymer. One the other hand, manufacturers can producepolymers that are differentiated under TSCA even though they consist of essentiallythe same molecules. The problems of discrimination and identification can bemore difficult when polymers are manufactured from other polymers. Implicit pre-requisites that arise from the recordkeeping and reporting requirements are (1) toestablish the chemical identity of the polymer; and (2) to confirm that the identityof the polymer is unique compared to other polymer identities for which you previ-ously have invoked the exemption.

In 1997, the EPA published a guidance document for the 1995 polymer exemp-tion.2/ This guidance states that it does not supercede any provision in the amendedpolymer exemption rule, but there is a significant change in the reporting provisionknown as the “two-percent rule.” There is no specific support for this belated guid-ance in the polymer exemption itself. Prior to the publication of the guidance, onecould not anticipate this change, which is discussed in more detail below.

As a final introductory comment, we note that the lure of eligibility under thepolymer exemption is, perhaps, its greatest potential liability. Because the exemp-tion allows immediate manufacture of an eligible polymer, there is a moral hazardthat the internal review will be inadequate. If an error is made, another internalcertification can be quickly made. Perhaps that certification will be correct. Surelya series of errors is an unintentional result of relaxed qualifications for the polymer


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exemption. We hope that the guidance provided below will materially assist youwith not making an error the first and every time this exemption is invoked.

I. Polymer Exemption Requirements

Like the original exemption, the amended exemption has three types ofrequirements: (1) a polymer definition, (2) exclusions, and (3) conditions. In ourexperience, the conditions are most likely to limit the availability of the exemption,so we address the conditions first, even though in the exemption regulation theyappear last.

A. Paragraph (e) ConditionsThree alternative conditions are provided in paragraphs (e)(1), (e)(2), and

(e)(3) of 40 C.F.R. § 723.250. Basically, paragraphs (e)(1) and (e)(2) apply to twonon-overlapping ranges of molecular weight. Paragraph (e)(3), is a special casecondition; it applies to certain polyesters and has no explicit molecular weightrequirement. Because it is the simplest of the three and, if applicable, eliminatesthe need to satisfy more onerous requirements, its applicability is preferable andshould be considered first. Due to its simplicity, (e)(3) is also easy to use or elimi-nate. If your candidate substance has no ester linkages in it or its precursors con-tain any atomic elements other than carbon, hydrogen, oxygen, silicon, or chlorine,move on to (e)(1) and (e)(2).

1. Condition (e)(3)Paragraph (e)(3) applies to polyesters. To be eligible under (e)(3), polymers

must satisfy a minimal polyester definition. The other (e)(3) requirement is thatpolyesters must be manufactured from a list of acceptable reactants. The amendedlist of acceptable reactants excludes some that were originally listed withoutCASRNs, but it includes more reactants than were on the 1984 list. Please note thatevery one of the precursors on the list may not be listed on the Chemical SubstanceInventory (Inventory), but they must be so listed or manufactured under an applica-ble TSCA section 5 exclusion or exemption from premanufacture notification.

The list of acceptable reactants is given in the table at 40 C.F.R. § 723.250(e)(3).A useful general observation, when considering whether your reactants are listed(e)(3) precursors, is that all of the reactants on the list contain only the atomic ele-ments carbon, hydrogen, oxygen, and silicon, with one exception. There is one listedprecursor that consists of the hydrolysis products of reactants that include the elementchlorine. Therefore, chlorine might remain in this precursor and in the polyesters cre-ated from it. For example, without consulting the list, one knows that a precursor thatcontains nitrogen, fluorine, phosphorus, or sulfur obviates the (e)(3) conditionbecause there is no listed precursor that contains these atomic elements.

Polymer Exemption Requirements

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2. Condition (e)(1)Paragraph (e)(1) covers polymers with number-average molecular weights

(NAMWs) of 1000 and above but less than 10,000. At the same time, polymers inthis molecular weight range also must always have a molecular weight distributionsuch that there is less than 25 weight percent with molecular weights below 1000and less than 10 weight percent with molecular weights below 500. Both criteriamust be simultaneously met for the condition to apply.

In addition, polymers that meet the molecular weight criteria of the (e)(1) con-dition must also satisfy an important limitation for certain reactive functionalgroups (RFGs). Because this RFG limitation functions more like an exclusion, it isdiscussed below with other exclusions.

3. Condition (e)(2)Paragraph (e)(2) covers polymers with molecular weights of 10,000 or greater.

The concomitant requirements for molecular weight distribution are oligomer con-tents of less than five weight percent with molecular weights less than 1000 andless than two weight percent with molecular weights less than 500.

Essential Molecular Mass Data

In comparing the criteria in paragraphs (e)(1) and (e)(2) above, an unintendedgap is apparent: certain polymers that should be eligible under the exemption maynot satisfy either provision. Consider a polymer with a NAMW of 10,100 and amolecular weight distribution that includes three weight percent of polymer mole-cules with less than 500 molecular weight. If such a polymer is eligible under thisexemption at all, it would have to qualify under (e)(3). A polymer with a NAMWof 9900, could be eligible even if its oligomer content with molecular weightsbelow 500 were nine percent, three times higher than the oligomer content of thepolymer above that has a higher NAMW!3/

In addition, polymers that qualify under (e)(2) are subject to a (d)(5) limitationregarding water-absorbing ability. Although this limitation is an exclusion that inprinciple applies to any polymer that qualifies under any of the three conditions, infact this exclusion can not apply to (e)(1). Due to its unlikely application to (e)(3),its function is primarily that of an (e)(2) limitation. Due to its ambiguity and itspromulgation as an exclusion under paragraph (d), this limitation is discussedbelow with the other exclusions.

Condition MW min MW max % <500 max % <1000 max

(e)(1) 1000 <10,000 10 25

(e)(2) 10,000 none 2 5


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B. ExclusionsThere are five exclusions under paragraph (d) in the 1995 polymer exemption.

The first three exclusions under paragraph (d) are revamped versions of exclusionsfrom the original exemption rule. The fourth and fifth exclusions are new. Thenew exclusions concern the regulatory status of precursors and the capacity of apolymer to absorb water, respectively. The water-absorption exclusion, as notedabove, applies primarily to condition (e)(2).

As also noted earlier, there are two other additional exclusions that are notexplicitly listed as exclusions but function as such and are discussed in this sectionof this document. One such exclusion is the reactive functional group exclusionthat is tied to condition (e)(1). The second additional exclusion is the implicitmolecular weight floor of 1000 under the (e)(1) condition. Both additional exclu-sions are discussed below. Due to its preemptive effect, we begin with the newfourth exclusion.

1. (d)(4); Unreviewed ReactantsThis new exclusion at paragraph (d)(4) does not allow a manufacturer or

importer to commercialize a polymer under the polymer exemption if any one ormore of the reactants used or incorporated at two weight percent or more are notlisted on the TSCA Inventory or manufactured under an applicable exemption tosection 5 of TSCA. Used and incorporated have special meanings that are dis-cussed below under the heading, Two-Percent Rule.

The (d)(4) exclusion for polymer precursors that have not been reviewed or“grandfathered” as existing chemicals in the U.S. is likely to be a problem primarilyfor polymer importers. In order to legally manufacture any substance for a non-exempt commercial purpose in the U.S., no reactants may be imported or manufac-tured in violation of section 5 of TSCA. Therefore, all reactants that are legallycommercially available in the U.S. will be existing substances or subject to an exclu-sion or exemption from reporting under section 5 of TSCA. Under the 1995 poly-mer exemption, if the reactants used are subject to such a section 5 exclusion orexemption, the reactants must meet the requirements of the polymer exemption.Outside of the United States, reactants are available that do not meet these criteria.On the other hand, reactants that are not listed on the TSCA Inventory are not neces-sarily disqualified as precursors to a polymer under the 1995 polymer exemption.

Prospective importers of polymers that include a reactant that is neither includ-ed on the Inventory nor manufactured under an applicable exemption or exclusionare at a disadvantage. A manufacturer or importer of a polymer is not in a positionto make a bona fide inquiry under 40 C.F.R. § 720.25 as to the Inventory status of areactant used to manufacture the polymer unless the importer or manufacturer ofthe polymer intends to manufacture or import the reactant for a commercial pur-pose. They may need to overcome the (d)(4) exclusion by filing a PremanufactureNotice (PMN) for the reactant and, at least once, importing the reactant.


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Alternatively, an importer could file a PMN for the polymer without qualifying thereactant. Either remedy involves additional time and money.

2. (d)(1); Positively Charged PolymersThe exclusion under paragraph (d)(1) eliminates a cationic or potentially

cationic polymer from the exemption unless its charge density is sufficiently low orit is a non-dispersible, non-soluble solid. Cationic polymers are those that includemolecules that contain a positive charge. Polymers that are associated with non-polymeric, positive counterions are not cationic polymers. Polymers are potentiallycationic if they are reasonably anticipated to become cationic in a natural aquaticenvironment (e.g., polymers that bear one or more amino groups or isocyanategroups4/ that can hydrolyze to amino groups). A polymer is ineligible for theexemption if the equivalent weight of all cationic groups is less than 50005/ —unless the polymer is a solid that is neither soluble nor dispersible in water and willonly be used as a solid.6/ A threshold of 5000 equivalent weight means that themass of the substance that constitutes one molar unit of positive charge is 5000grams or greater. The (d)(1) exclusion applies solely to cationic groups; therefore,while the presence of potentially cationic groups might trigger this exclusion, suchpolymers could still be eligible for the polymer exemption if the actual charge inthe natural aquatic environment is below the threshold concentration.7/ Please notethat simultaneous incorporation of negative charge does not cancel positive chargefor the purpose of this exclusion.

In addition, please note that equivalent weight is not necessarily related to molec-ular weight. The molecular weight may be high or low for the same equivalent weightand vice versa. The equivalent weight of a substructure is only related to molecularweight when the mean number of substructures per molecule is accurately known.

3. (d)(2); Atomic Element LimitationsThe second exclusion limits the identities of the atomic elements that consti-

tute an eligible polymer. All eligible polymers must contain as an integral part oftheir composition two or more of the atomic elements, carbon, hydrogen, nitrogen,oxygen, silicon, and sulfur. In the original polymer exemption this kind of require-ment was accompanied by a requirement for a minimum level of carbon. Thereforein the original polymer exemption, one of the two elements had to be carbon andessentially the balance of the mass had to consist of hydrogen, nitrogen, oxygen,silicon, or sulfur atoms or any combination of one or more of these atoms.

Additionally, the specific monatomic counter ions, Na+, Mg+2, Al+3, K+, andCa+2 are permitted. Also, chlorine, bromine, and iodine are permitted whether theyare covalently bound to carbon or as the specific monatomic counter ions, Cl-, Br-,and I-. Fluorine is permitted, but only if it is covalently bound to carbon; fluorineis never permitted as any ion. Either alone or in any combination, the atomic ele-ments, lithium, boron, phosphorus, titanium, manganese, iron, nickel, copper, zinc,tin, or zirconium are permitted at less than 0.20 weight percent total.


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No other atomic elements are permitted such as cerium or lead. Unusual oxi-dation states of the permitted counterions, and excess combinations of, say, phos-phorus and boron also are excluded under this limitation. An important aspect inapplying this limitation is that it is not relevant to impurities. Impurities are notconsidered “an integral part of the polymer’s composition.”

4. (d)(3); InstabilityPolymers cannot be manufactured under the amended polymer exemption if

they substantially degrade, decompose, or depolymerize. Arguably, this exclusionhas been modified from the original exclusion for polymer instability. The EPA hasnow made it explicit that this limitation applies if the polymer substantiallydegrades, decomposes, or depolymerizes — or is designed (or can be reasonablyanticipated) to substantially degrade, decompose, or depolymerize — prior to, dur-ing, or after use. Under the original exemption, EPA generally limited its consider-ation of degradation, decomposition, and depolymerization issues to the use of thepolymer and not its eventual disposal. As it now stands, a polymer is not eligibleunder this exclusion if the polymer substantially degrades, decomposes, or depoly-merizes, for example, after disposal in a wastewater treatment plant.

EPA maintains that the exclusion in the final rule is substantively the same asin the original rule. The difference in emphasis, however, is potentially significant.On one hand, the exclusion seems to reward the absence of degradation data,assuming susceptibility to degradation is not apparent. On the other hand, alkydresins and other polymers might be ineligible because they could be “reasonablyanticipated to substantially degrade, decompose, or depolymerize … after use, eventhough they are not actually intended to do so.” Many polymers were judged to beeligible under the original exemption because they were not designed nor reason-ably anticipated to substantially degrade, decompose, or depolymerize in use. Nowsubstantial degradation in a wastewater treatment plant might be reasonably antici-pated for those same polymers.

Further guidance from EPA on the proper application of this exclusion fromthe 1995 polymer exemption would be very desirable. In the absence of usefulguidance, part of the previous exemption scope appears to be lost for polymers thatcould be substantially degraded during disposal. Rather than filing PMNs, polymermanufacturers and importers could seek pre-exemption determinations from theEPA as to whether degradation will be considered substantial.

It may also be useful to note that, although biopolymers are no longer explicitlyexcluded from the polymer exemption, to be eligible, biopolymers must not substan-tially degrade, decompose, or depolymerize. Most biopolymers can be reasonablyanticipated to substantially degrade, decompose, or depolymerize — prior to, during,or after use.


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5. (d)(5); High Molecular Weight, Water-Absorbing Polymers This provision excludes certain water-absorbing polymers from eligibility for

the amended polymer exemption. A water-absorbing polymer is defined as one“that is capable of absorbing its own weight of water” and has a number-averagemolecular weight (NAMW) equal to or greater than 10,000.8/ In other words, apolymer that has a NAMW of 10,000 or more and that is capable of absorbing amass of water that is equal to, or more than, the mass of the polymer may not bemanufactured or imported under this exemption.

As discussed in the preamble of the 1995 polymer exemption rule,9/ the exclu-sion for water-absorbing polymers is intended primarily to address concerns for“super absorbent” polymers, which are also known as “super slurpers.” The exclu-sion responds to information received under section 8(e) of TSCA for a water-absorbing polyacrylate.

In that 8(e) case, the polyacrylate in question had a NAMW of about1,000,000 and could absorb about 100 times its own mass of water. The EPAbelieves that it is reasonable to set the exclusion two orders of magnitude belowthese levels: 10,000 NAMW and water absorption of one times its own mass. TheEPA contends that a NAMW of less than 10,000 generally mitigates potentialhealth hazards for polymers because they may be detoxified through differentmechanisms in contrast to polymers with higher NAMWs. Perhaps the most usefulinsight from this information is that “super slurpers” have the capacity to absorbabout 100 times their own mass of water, yet not dissolve.

The paragraph (d)(5) exclusion for water-absorbing polymers will be problem-atic mainly for polymers that might be eligible under paragraph (e)(2). While the(d)(5) exclusion applies across the entire exemption, it only applies to polymerswith NAMWs of 10,000 or greater. By its own terms, this exclusion does not applyto condition (e)(1). Polyesters manufactured only from reactants that are listedunder paragraph (e)(3) and that have molecular weights of 10,000 or more are notlikely to meet the definition of water-absorbing. The permissible reactants for(e)(3) polyesters are not conducive to absorbing water after being incorporated intopolymers.

It sounds obvious to say that the water-absorbing exclusion applies whenever agiven polymer is water-absorbing. But it is not as obvious as it sounds. Unlikesome other aspects of polymers, the property of water absorption generally does notattach to a polymer’s chemical identity. However, for a particular version of agiven polymer, the capability to absorb water can be characterized. Conversely, ifsome version of a polymer manifests the degree of water absorption that this exclu-sion prohibits, it does not mean that the polymer is necessarily ineligible for theexemption.

Determining whether a given substance is a water-absorbing polymer mightnot be straightforward. The EPA has not established a test protocol. Moreover,polymers are often manufactured in association with solvents and other substances


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(including residual precursors) that makes the assessment of the water-absorbingstatus of the polymer, per se, unclear or impractical. The definition that a water-absorbing polymer is “a polymeric substance that is capable of absorbing its ownweight of water” does not provide ample guidance.

The capacity of every polymer to absorb water need not always be determinedfor purposes of establishing compliance with the polymer exemption. In lieu ofanything else, the following guidance is offered, although it should be noted that itis unofficial.

You might find that the polymer in question is totally soluble in water or in asolvent that consists of water to a significant extent. Alternatively, you might findthat, as manufactured, the polymer is dispersed in water or in a solution that con-tains a significant level of water. The fact that a polymer is formed as a waterbornesolution or dispersion does not necessarily mean that the polymer has absorbed itsown weight in water. The polymer phase of the emulsion may be hydrophobic withlittle or no absorbed water — or it may be hydrophilic and pervaded with a greatdeal of absorbed water.

Moreover, the exclusion pertains to the capacity of a polymer to absorb water.Polymers that are manufactured as aqueous solutions or dispersions may escape thewater-absorbing exclusion on the basis that they have absorbed as much water aspossible and are not capable of absorbing any more.

At the other extreme, the polymer might not have sufficient affinity for waterto be considered water-absorbing. Clearly, hydrophobic polymers that are notappreciably wet by water do not need to be evaluated for their non-water-absorbingcapacity.

If a polymer is isolated from its solution or dispersion and cannot be dissolvedor dispersed again in water, such a polymer should not be considered water-absorb-ing. However, if such a polymer will be processed in a manner that creates parti-cles, and those particles are capable of absorbing their own weight of water withoutdissolving, the polymer should be considered excluded because the risks that theEPA seeks to avoid with this exclusion for high molecular weight polymers mightbe expected to be realized.

In some situations, the water-absorbing capability of a given polymer mightneed to be evaluated. If a particular polymer might absorb and retain enough waterto be considered water-absorbing, the following test is suggested. The test shouldonly be carried out on a properly selected sample.

The sample of the polymer should be that version of the polymer that isintended to be commercialized that has the greatest capability for water absorption.The water-absorbing exclusion provided by paragraph (d)(5) applies to all produc-tion of the polymer for the exemption’s conditions under paragraph (e)(2) and allversions of polyesters that have a NAMW of 10,000 or greater under paragraph(e)(3). The fact that a particular version of a polymer is not water-absorbing does


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not qualify any other version of the same polymer if it is water-absorbing. In short,the exclusion must never be violated by any version even if some versions satisfythis limitation.

If possible, determine the dry mass of a sample of the polymer in question thatis free of precursors and other associated substances. Then contact the sample witha quantity of water equal to twice the polymer’s dry mass. We suggest using nor-mally available, deionized water. Record the pH of the water used to establish thatthe pH is within the usual bounds of neutrality. Reasonable conditions during thecontact would be one hour at room temperature. The nature of the contact shouldbe such that there is a reasonable opportunity for the polymer to absorb the water.Subsequently, physically separate the wet polymer from excess gross water.Determine the mass of the polymer plus whatever mass of water that has beenabsorbed and retained. If this wet mass is less than double the dry mass or more,the polymer is not sufficiently water-absorbing to be excluded from the exemptionby this provision.

The EPA has not considered how time, temperature, pH, water purity, apparatus,procedure, nature of the polymer, interpretation of data, kinetics, or other considera-tions will influence the results. If there is significant water absorption, it might beprudent and appropriate to submit a suitable protocol and data to the EPA forapproval before relying on any particular results.

6. Reactive Functional GroupsA reactive functional group (RFG) is defined as an atom or associated group of

atoms in a chemical substance that is intended or can be reasonably anticipated toundergo further chemical reaction. This provision is expressed in the regulation asa limitation to the (e)(1) condition, not as an exclusion. Although the reactive func-tional group limitation it is not applicable to the (e)(2) and (e)(3) conditions, itmight be better understood as an exclusion, albeit one that only applies to (e)(1).

There was an RFG exclusion in the original polymer exemption. In theamended exemption, the RFG exclusion, like the entire exemption itself, is morecomplex compared to the original version. Nonetheless, it allows more polymers tobe exempt.

More polymers are potentially exempt due to both the exclusion’s sole applica-bility to the (e)(1) condition and other complicating refinements. In fact, therefinements can be extremely complicated if one has different kinds of RFGs pres-ent in the polymer’s molecules. A “quick and clean” approach is to identify theequivalent weight for all RFGs that will form an ionic or covalent linkage to anamino acid. If that equivalent weight is less than 5000 for all such groups com-bined, the polymer is probably excluded by this provision, but there is hope that itis not excluded unless the equivalent weight is less than 1000.

The (e)(1) limitation only applies when the polymer’s molecular weight is1000 or more, but less than 10,000 and the oligomer levels are less than 25 and 10


11

weight percent below 1000 and 500 molecular weight, respectively. In otherwords, the RFG exclusion does not apply to polymers (a) whose molecular weightwill always be 10,000 or more under condition (e)(2), (b) polymers whose oligomerlevels are equal to or greater than 25 and 10 weight percent below 1000 and 500molecular weight, respectively, or (c) that are polyesters under condition (e)(3).

In the amended polymer exemption, the description of what are and what arenot RFGs has been edited from the original descriptions. When the 1995 polymerexemption was first discussed in 1995, the tiers of RFGs were characterized asthree “flavors”: tart, bland, and sweet. In the EPA’s 1997 guidance, the sameapproach was taken and the tiers of RFGs were characterized as High, Moderate,and Low Concern. We use those terms now to assist in comparison with the EPA’sguidance.

One can consult the exemption for more details. EPA’s guidance gives moreexamples, but the calculations shown are flawed. The RFG exclusion is complexand the following explanation should be considered to be abridged.

The RFG exclusion permits a polymer to be manufactured or imported underthe polymer exemption for condition (e)(1) if it has a combined concentration of(High Concern) RFGs such that the equivalent weight of all RFGs combined isgreater than 5000. RFGs that are not listed must be assumed to be in the mostrestricted (High Concern) group. Guidance as to what might be in this HighConcern category is implicit in the list of Moderate Concern RFGs and from thepreamble to the current and original regulations. For example, because “alkoxysi-lanes with greater than C2-alkoxysilanes” (i.e., propoxy- and higher alkoxysilanes)are Moderate Concern RFGs, methoxy- and ethoxysilanes are High Concern RFGs.

Moderate Concern RFGs are permitted at higher concentrations for polymersthat otherwise satisfy the (e)(1) condition. For these RFGs of Moderate Concern,the equivalent weight can be as low as 1000.10/ There is a list of Moderate ConcernRFGs at 40 C.F.R. § 723.250 (e)(1)(IJ)(B). Note that this list does not includeamines nor ureas, per se; these groups are not included in the listings. What areincluded are methylolamines and methylolureas. Amines are considered HighConcern, while ordinary ureas are not considered RFGs.11/ A common reactivegroup in the Moderate Concern category is the epoxy group. Low Concern RFGsare permitted without restriction.12/ This list is described in 40 C.F.R. § 723.250(e)(1)(IJ)(A). The status of some groups that are not listed may be unclear. If indoubt, assume the group is High Concern or seek clarification.

In many cases, the abridged discussion here will suffice. A full discussion of theRFG provisions is beyond the scope of this paper. Please see 40 C.F.R. § 723.250and the EPA’s 1997 guidance. However, we caution that there are calculation errors inthe EPA’s guidance on this subject that have not been corrected.


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7. Molecular Weight Less Than 1000While not explicitly stated in the polymer exemption, it might be useful to

remember that polymers with NAMWs less than 1000 are excluded from eligibilityunless they are (e)(3) polyesters 13/ manufactured from the list of acceptable precur-sors. Except for the polyesters eligible under (e)(3), the 1000 molecular weightthreshold reinforces the effect of the polymer definition.

In practice, polymers that qualify for the 1995 exemption will have NAMWssomewhat higher than 1000. This is a consequence of the 1000 threshold beingtied to oligomer contents. Few polymers will have NAMWs very near 1000because of the concomitant requirement that no more than 25 weight percent of thecomponents of such polymers can have NAMWs below 1000.

C. Polymer DefinitionThis definition is based on the original exemption definition of a polymer and

apparently modified for no practical purpose. The original definition was used fornearly a decade without a problem. Both the original and amended polymer defini-tions are intended to draw a line between polymers and non-polymers and notexclude any conventional, synthetic polymers.

Under the 1995 polymer exemption, a polymer is a chemical substance thatconsists of not less than 50.0 weight percent (a simple majority) of polymer mole-cules and less than 50.0 weight percent of molecules with the same molecularweight. The polymer molecules must be distributed over a range of molecularweights and the differences among polymer molecules are primarily due to differ-ences in the number of internal monomer units. This definition depends on a multi-tude of defined terms.

A monomer unit is the reacted form of a chemical substance that is capable offorming covalent bonds with two or more like or unlike molecules under the condi-tions of the relevant polymer-forming reaction. It is an atom or a group of atomschemically derived from a corresponding monomer, i.e., -(Ma´)- derived from Ma.For example, a phthalate monomer unit, C8H4O3, corresponds to a phthalatemonomer such as phthalic anhydride, phthalic acid, a half-acid ester of phthalic acid,or any other phthalate subunit precursor that has functioned as a monomer. Internalmonomer units are monomer units that have been derived from monomers that havefunctioned as monomers, i.e., they are covalently bonded to at least two other mole-cules and generally are incorporated into the same polymer molecule more than once.

A polymer molecule contains a sequence of at least three monomer units thatare covalently bound to each other and to at least one other monomer unit or otherreactant. Sequence means that the monomer units under consideration are covalent-ly bound to one another and form a continuous string uninterrupted by units otherthan monomer units within the polymer molecule. The monomer units need not beidentical. However, it is important to realize that a substructure that is covalentlybonded to two or more other substructures might not be considered a monomer unit.


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A monomer unit is never a substructure if it is derived from a reactant that does notpolymerize under the conditions of the relevant polymer-forming reaction.14/ Such anon-monomer substructure is considered to interrupt the sequence of monomer units.This interpretation is closely linked to the term, other reactant.

An other reactant “means a molecule linked to one or more sequences ofmonomer units but which, under the relevant reaction conditions used for the par-ticular process, cannot become a repeating unit in the polymer structure.”15/ Otherreactants are those that, under the relevant reaction conditions, have not or cannotbecome a repeating unit in the polymer’s structure. A chemical substance that islinked to a molecule through only one covalent bond is an other reactant even ifthere are many such substructures in the same molecule.

The polymer definition acts as an entry gate to the polymer exemption. If thedegree of polymerization is insufficient, or the if the distribution of molecularweights is too narrow, the substance is not eligible for the exemption. The require-ment that the minimum average molecular weight be 1000 under the criteria forparagraph (e)(1) also generally provides a minimum degree to which polymeriza-tion must be carried out for both criteria (e)(1) and (2). A NAMW of 1000 is oftena surrogate for the polymer definition for reaction products whose reactants havethe capability to polymerize, and will meet the criteria for (e)(1) but are not eligibleunder the criteria for (e)(3). If the criteria for the (e)(2) condition are met, it wouldbe extremely difficult not to satisfy the polymer definition.16/ For the (e)(2) condi-tion, the polymer definition is essentially redundant. The principal impact of thepolymer definition is to ensure a minimal degree of polymerization for polyestersunder (e)(3).

II. The Two-Percent Rule

The “two-percent rule,” as it is commonly called, is a rule only in the sense thatthe word refers to a procedure that is usually followed. Under administrative law, arule is a law created by administrative agencies of the government. The “two-per-cent rule” is merely a provision for reporting the chemical identity of polymers.17/

Initially it was in the rule that established Initial Inventory Reporting under TSCA.Subsequently, the “two-percent rule” was incorporated into the rule for preparingpremanufacture notifications at subparagraph (iii) of 40 C.F.R. § 720.45(a)(2) asamended:

(2) For a polymer, the submitter must report the following . . .

(iii) For monomers and other reactants used at 2 weight percent or less (basedon the dry weight of the polymer manufactured), indicate on the PMN form anysuch monomers and other reactants that should be included as part of the poly-mer description on the Inventory, where the weight percent is based on either (A)the weight of the monomer or other reactant actually charged to the reaction ves-sel, or (B) the minimum weight of monomer or other reactant required in theoryto account for the actual weight of monomer or other reactant molecules or frag-ments chemically incorporated (chemically combined) in the polymeric sub-stance manufactured.18/

The Two-Percent Rule

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According to this provision, monomers and other reactants used or incorporat-ed (whichever is less) at no more than two percent are only captured in polymernames at the option of the submitter. The level of use is relatively straightforward;the level of incorporation is relatively complex.

In the context of the two-percent rule, the percent used means the weight per-cent calculated from the mass of the precursor charged divided by the mass of theproduct formed (both on a 100-percent active basis). The calculation is independ-ent of the degree of chemical incorporation of the polymer, so long as there is somechemical incorporation.

The percent incorporated in the amended two-percent rule means the weightpercent calculated from the minimum mass of the precursor that theoretically couldaccount for the mass or portion of the mass of the precursor that is chemicallyincorporated divided by the mass of the product formed (both on a 100-percentactive basis). Where the percent incorporated is accessible and can be supported, itcan lead to a lower percentage for decision making instead of the percent used.This can mean that polymers that used greater than two weight percent of a reactantand were denied eligibility solely on that basis could now be eligible if the degreeof incorporation can be shown to be two weight percent or less. The percent incor-poration is not the percentage of the mass of the reactant incorporated.

Analytical data or appropriate theoretical calculations must be maintained atthe site of manufacture or import to support the incorporation level. Theoreticalcalculations are permitted if it can be documented that analytical measurement isnot feasible or necessary to support the determination of how much of a reactant ischemically incorporated.

Simply stated, the two-percent rule means (a) that precursors of a polymer thatare either used or incorporated at no more than two weight percent, may be includ-ed in the description of a polymer manufactured from those precursors while (b)precursors used or incorporated (whichever is less) at more than two weight per-cent must be included in the chemical description reported and ordinarily will bereflected in the name of the polymer.19/

Please note that the two-percent rule does not mean that a precursor reflectedin the description of a polymer must be used or incorporated at more than twoweight percent. Conversely, a precursor reflected in the description of a polymergenerally must not be omitted or reduced to only a probability of being chemicallyincorporated.

We have confirmed that, under the EPA’s 1997 (current) polymer exemptionguidance, the reporting provision known as the two-percent rule does not operatethe same way as it does outside of the polymer exemption. Under the current poly-mer exemption, the EPA interprets the two-percent rule to mean that if a precursoris used or incorporated at less than or equal to two weight percent,20/ the manufac-turer or importer cannot include that precursor in the “identity” of the polymer. If amanufacturer or importer uses or incorporates a certain monomer or reactant in an


15

exempt polymer at less than or equal to two weight percent, the manufacturer orimporter may not later use or incorporate that monomer or reactant at greater thantwo weight percent under the exemption for the same polymer. In other words,there is no option by which a monomer or other reactant may be included in the“identity” of the exempt polymer if its initial concentration is less than or equal totwo weight percent. One part of the reporting provision is unchanged: if a reactantor monomer is used at greater than two weight percent in an exempt polymer, thereactant or monomer must not be eliminated completely from the polymer.

One application of EPA’s guidance is not certain. If a polymer that was initial-ly manufactured under the polymer exemption with a given monomer or reactantused or incorporated at greater than two weight percent, is it the same polymerunder the exemption if the same monomer or reactant is subsequently used orincorporated at a concentration that is equal to or less than two weight percent butgreater than zero weight percent. Based on the EPA’s guidance, it would appearthat the subsequent version of the polymer as just described, would be the samepolymer under the exemption as the initial polymer. Ordinarily, any precursor thatis reflected in the description of a polymer may be used at any concentrationgreater than zero (so long as the concentration does not offend some requirement).The same understanding should apply under the polymer exemption. We havesought confirmation of this aspect of the application of the two-percent rule fromthe EPA, but it is not forthcoming.

EPA’s guidance concerning the two-percent rule under the polymer exemptioncan create a problem. If precursors are to be used or incorporated both at less thanor equal to two weight percent and at greater than two weight percent, one hasmore than one polymer to report. If there are n precursors used or incorporatedboth at less than or equal to two weight percent and at greater than two weight per-cent, there are 2n potential polymers. In each pair, one polymer must include thegiven precursor at greater than two percent and another polymer that may omit theprecursor or use or incorporate it at no more than two weight percent. Under theordinary two-percent rule, the manufacturer or importer can designate whether theprecursor used or incorporated at less than or equal to two weight percent is to beincluded in or omitted from the polymer’s chemical identity.

If a polymer will be manufactured or imported with any of its precursors atgreater than two weight percent,21/ that polymer may have the same chemical identityif any of the same precursors are subsequently used or incorporated at two weightpercent or less so long as they are not eliminated. If that polymer also will be ini-tially manufactured or imported such that any of its precursors that were at twoweight percent or less, become manufactured or imported where they become morethan two weight percent, separate chemical identities must be established and sepa-rate records, certifications, and notices must be provided if the guidance is followed.

According to EPA’s polymer exemption guidance, the “two-percent rule” oper-ates differently within the 1995 polymer exemption, than the way that it operatesoutside of the exemption. If challenged, this particular interpretation might not be

Reporting and Recordkeeping

16

sustained. Manufacturers and importers do not have adequate notice from mereguidance because it is not part of the rulemaking process. One could not know thata polymer needs two chemical identities for polymers in which there is a precursorused or incorporated at more than two weight percent and two weight percent orless or that if they reduce the level of a precursor from a level above two percentthat they will have the same polymer or a different polymer. Among other reasons,such as continuity with the initial interpretation of the “two-percent rule,” the EPAshould retract its guidance on this point. Nonetheless, courts often give deference toan Agency’s interpretations of a rule.

III. Reporting and Recordkeeping

A. ReportsReports postmarked no later than January 31 must be submitted by each manu-

facturer or importer after any calendar year in which a polymer was manufacturedor imported under the polymer exemption. The report must state merely the num-ber of polymers manufactured or imported for the first time under the terms of theexemption in the year preceding the notice. Each polymer under the exemptiongenerally is reported only once for each manufacturer or importer.22/ If no polymerswere manufactured or imported under the terms of the exemption, no report isrequired. There is no requirement to give the identity or any other information con-cerning the polymers, per se. The only other information required in the year-endreport is the name and address of the manufacturer or importer and the name andphone number of a technical contact. See, 40 C.F.R. § 723.250(f). Any or all por-tions of the year-end report may be claimed as confidential business information.

B. RecordsThe manufacturer or importer must identify and maintain records, pursuant to

40 C.F.R. § 723.250(g), that include the following information:

1. a specific chemical name and CASRN (or EPA-assigned AccessionNumber) for each reactant. At this point in the regulations, (subpara-graph (g)(1)) EPA notes that reactants that introduce chemical or physi-cal properties (including reactive functional groups) or atomic elementsthat render the polymer ineligible for the exemption are not allowed atany level. The phrase “at any level” does not seem to be intended to betaken literally. A reasonable interpretation is that EPA is simply intend-ing to caution that a polymer must qualify for the exemption. There isno exception if the reactant that contributes an impermissible propertymay be used or incorporated at less than two percent. In other words,one would violate one or more terms of the exemption if one used anexplicitly offending reactant — even if it were used (or incorporated) atless than two weight percent. For example, any level of use of a reac-tant that contains an impermissible atomic element according to the(d)(2) exclusion would violate the exemption. Use or incorporation of


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a reactant that contains a High Concern RFG might or might not causethe polymer to violate the exemption, depending on its level.

2. a representative structural diagram, if possible.

3. information to demonstrate that the polymer is not specifically exclud-ed from the polymer exemption by any of the exclusions set forth atparagraph (d) of 40 C.F.R. § 723.250.

4. information to demonstrate that the polymer meets at least one of thethree conditions of the polymer exemption set forth at paragraph (e) of40 C.F.R. § 723.250.

5. the date of first commercialization under the polymer exemption.

6. production or importation records for the first three years of manufac-ture or importation from the date of first commercialization under theexemption.

7. analytical data or (if it can be documented that an analytical determina-tion cannot be made or is unnecessary) theoretical calculations to sup-port the molecular weight, oligomer concentrations, or reactant levelsused at more than two weight percent but incorporated at two weightpercent or less.

8. certification as of the date of first manufacture or import that (1) thepolymer is manufactured or imported for a commercial purpose otherthan research and development, (2) all information in the certificationis truthful, and (3) the polymer is eligible for the exemption.

The records must be retained for at least five years from the date of com-mencement of manufacture or import at the manufacturing or importing site. Theserecords must be submitted to the EPA upon written request within 15 working daysof receipt of the EPA’s request. In addition, access to or copying of these recordsmust be permitted at all reasonable times upon the EPA’s request.

IV. Summary

Although the 1995 polymer exemption is presented as (1) definition, (2) exclu-sions, and (3) conditions, it is more comprehensible in reverse order. Within theconditions, there are limitations that are more logically considered with the exclu-sions. Even among the exclusions, the order of presentation is not the order of like-ly importance. The determination of eligibility is complex; recordkeeping andreporting appear simple but both pose several traps. With appropriate knowledgeand experience, one can comply with the polymer exemption. We trust this guid-ance will provide useful insights and encourage use of the exemption.


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1/ 60 Fed. Reg. 16316 (Mar. 29, 1995).

2/ U.S. EPA “Polymer Exemption Guidance Manual” EPA 744-B-97-001(Jun. 1997).

3/ It is our understanding that the 10,000 NAMW limitation in paragraph (e)(1)served an important purpose in a draft of the exemption. We note that if the phrase “andless than 10,000” were deleted from paragraph (e)(1), the anomaly described here wouldvanish. In other words, polymers that had NAMW’s at 10,000 and above should be ableto qualify under the (e)(1) condition. It is unfortunate that polymers that could otherwisequalify for an exemption under (e)(1) become ineligible if their NAMW is too high! Atechnical correction to eliminate this unintended consequence would be appropriate.

4/ Amines and isocyanate groups are also reactive functional groups which arediscussed later.

5/ 40 C.F.R. § 723.250(d)(1)(IJ).

6/ 40 C.F.R. § 723.250(d)(1)(i).

7/ This can sometimes be calculated based on ionization constants and pH.

8/ Conventionally, the units of molecular masses or weights have not been statedexplicitly. The units have been understood to be atomic mass units. Recently, EPA’sregulations have referred to atomic mass units as daltons, so named after John Dalton,an English chemist and physicist.

9/ 60 Fed. Reg. 16319-16320 (Mar. 29, 1995).

10/ 40 C.F.R. § 723.250(e)(1)(IJ)(B).

11/ Certain chemically recognized groups are not considered RFGs so they are notspecifically included in the list of Low Concern RFGs. Under the 1995 polymer exemp-tion, Low Concern RFGs are treated the same as chemical groups that are non-reactive.

12/ 40 C.F.R. § 723.250(e)(1)(IJ)(A).

13/ See the definition of polyester at 40 C.F.R. § 723.250(b).

14/ This interpretation is important because in some circumstances it might causethe threshold for the degree of polymerization for polymer molecules to be much higherthan for alternative interpretations.

15/ 40 C.F.R. § 723.250(b) [Other reactant].

16/ For example, certain biopolymers such as enzymes might satisfy the (e)(2) condi-tion but have too narrow a molecular weight distribution to satisfy the polymer definition.

17/ 40 C.F.R. § 710.5(c) (now withdrawn).

18/ 40 C.F.R. § 720.45(a)(iii). The reference above in the quoted text to “as part ofthe polymer description on the Inventory” is the sole basis for inferring that the two-per-cent rule is applicable for interpreting Inventory listings. EPA has never published anyrules directly bearing on the nomenclature used or interpretations that apply to theInventory. The only formal rules have been in the context of reporting obligations forsubmitters.

Endnotes

Endnotes

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19/ There are exceptions for certain situations such as oxidation and the involve-ment of water. Water is usually not listed as a reactant.

20/ There is no guidance if, depending on the method of calculation, the level of theprecursor might be both above and below two percent.

21/ Using whichever available method (use or incorporation) gives the lower value.

22/ Note that a company might decide either to consolidate this reporting or reportby plant site or importing site. If not done on a company-wide basis this could be a bur-den, especially for imported polymers and could result in duplicative reporting. Inregard to the number of polymers reported per year, the requirement is company specif-ic, not site specific, although the report can be made on a per-site basis. However, theother records that must be kept are site specific.

Keller and Heckman LLPServing Business through Law and Science®

®

1001 G Street, N.W. • Suite 500 West • Washington, D.C. 20001Tel. 202.434.4100 • Fax 202.434.4646 • www.khlaw.com

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3074 Tsca Pocketguide POLYMER EXEMPTION

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