Polymer of low concern notification
Step 1—establish if its a PLC notification
Step 2: Notifying about a new Polymer of low concern
Your application must consist of:
- the completed application form for an assessment certificate (PLC Assessment Certificate Application (Form PLC-1)) with new chemical data items listed
- any other information about the polymer available to you
- (where required) applications to exempt information based on confidentiality or to vary the schedule of data requirements
- any application for third party information (Form 5).
Assessment process and outcomes
In normal circumstances we will assess a PLC notification within 90 days of the date of receipt of complete application.
Further information on PLCsExpand All
Reactive functional groups
The number of Reactive Functional Groups (RFGs) in a polymer is important in determining whether it meets the PLC criteria.
An RFG is defined as: 'an atom or associated group of atoms in a chemical substance that is intended or can be reasonably anticipated to undergo facile chemical reaction'.
RFGs are divided into three categories—low, moderate and high concern—to reflect the comparative reactivity of each functional group (see table below).
The criterion for determining the category is more qualitative than quantitative, and is based on the presence of chemically or metabolically-reactive or toxic (including eco-toxic) functional groups within the polymer.
RFGs in the low concern category generally lack reactivity, or have low adverse reactivity, in a biological setting.
There is no Functional Group Equivalent Weight (FGEW) cut-off for low concern RFGs under the PLC criteria.
RFGs in the moderate concern category have evidence of reactivity in a biological setting but the effects are not severe enough to place the functional group in the high concern category. Sufficient information must be available to be confident that the RFG is of moderate concern.
For a polymer to meet the PLC criteria, the FGEW cut-off for moderate concern RFGs is 1000.
RFGs in the high concern category have evidence of human health hazard—adverse effects in humans or conclusive evidence of severe effects in animals.
Where there is no information or insufficient or contradictory information on an RFG it defaults to the high concern category until sufficient information becomes available for it to be moved to another category.
For a polymer to meet the PLC criteria, the FGEW cut-off for high concern RFGs is 5000.
If a polymer does not meet the cut-off for moderate or high concern RFGs to meet the PLC criteria, it could still be considered a PLC if sufficient additional information is provided to negate concern caused by the RFGs present. This information should generally consist of toxicological studies on the notified polymer or a suitable analogue addressing the particular concern raised by the RFGs present.
For example, if a polymer contains sulfonyl halide RFGs with a FGEW <5000 then it would not be eligible to be a PLC under the PLC criteria as sulfonyl halides are potential sensitisers. However, if toxicological tests on the notified polymer or a suitable analogue show that the notified polymer was unlikely to be a sensitiser then it may still be acceptable for notification as a PLC.
A number of functional groups are not considered to be RFGs. These include carboxylic esters, ethers, amides, urethanes, sulfones and the nitro groups. This is provisional on the functional group not being modified to enhance its reactivity (for example, the dinitrophenyl ester of a carboxylic acid).
The following RFGs, although not listed in the regulations or represented in the table below, have been determined to be in the low concern category:
- Imidazolidinone groups
- Organic phosphate esters—however, the polymer must still meet the elemental criteria to be eligible as a PLC.
Reactive functional group categories
Conjugated olefinic groups not contained in naturally occurring fats, oils and carboxylic acids
Pendant acrylates and methacrylates
Unconjugated olefinic considered 'ordinary'
Halosilanes, Hydrosilanes, Alkoxysilanes1
Conjugated olefinic groups contained in naturally occurring fats, oils and carboxylic acids
Blocked isocyanates (including ketoxime-blocked isocyanates)
Alpha or beta lactones
Vinyl sulfones or analogous compounds
Halogens (except reactive halogen containing groups such as benzylic or allylic halides)
*Methylolamides, -amines2 or –ureas
*Un-substituted positions ortho and para to phenolic hydroxyl
*Imines (ketimines and aldimines)
Other RFGs not in low or moderate concern groups
1 Alkoxysilanes with alkoxy groups >C2 are listed as moderate concern by the United States Environmental Protection Agency (US EPA).
2 Amines are regarded as high concern RFGs. Polymers containing them are generally considered under cationic polymers.
*Denotes the group that is in the US EPA moderate concern category for which data and information to support placement in this category is unavailable to NICNAS. These RFGs will default to the high concern category pending provision of such data and information by industry and/or other parties to NICNAS.
Functional group equivalent weight
The FGEW is used to determine if the RFGs in a polymer are substantially diluted by polymeric material to allow the polymer to be a PLC.
The FGEW of a polymer is defined as the ratio of the Number Average Molecular Weight (NAMW) to the number of functional groups in the polymer. It is the weight of a polymer that contains one formula weight of the functional group.
The level of low concern RFGs in the polymer is not restricted. Low concentrations of RFGs are permissible in polymer molecules, but the quantity is restricted by the reactivity of the functional group/s in question.
How to calculate functional group equivalent weight
Unless the FGEW can be determined empirically by recognised, scientific methodology (typically titration), a worst-case estimate must be made for the FGEW.
All moderate and high concern functional groups must be taken into account when calculating FGEW.
Guidance for estimating FGEW using specific methods is in D2.1 and D2.2, including illustrative examples for each (end-group analysis and per cent charged method).
Method 1—End-group analysis
Equation 1: Calculating FGEW by simply counting the number of RFGs and dividing into the NAMW
where n = the number of RFGs in the monomer
 Reactive functional groups  Atom or small molecule that may bind chemically to other monomers to form a polymer
Linear polymers have the simplest polymer architecture: a linear chain: a single backbone with no branches.
For linear polymers, such as some condensational polymers (for example, polyesters and polyamides) the only RFGs are at the end of the chain because the others are used up in the condensation reaction. For linear polymers, where there are two RFGs per monomer, the FGEW is half the NAMW.
For example, for a polyamide of NAMW 1500 made from ethylenediamine and adipic acid, an amine group would be expected at each end of the polymer chain. Therefore, FGEW = 1500/2 = 750.
For polymers where branching occurs, the RFGs at the end of each branched chain must be counted.
For example, consider the polymerisation of pentaerythritol (4 reactive groups) with polypropylene glycol (2 reactive groups) and an excess of isophorone diisocyanate (2 reactive groups) to give a polymer of NAMW 3000.
Due to the branching of pentaerythritol and excess diisocyanate, the resultant polymer will theoretically have six isocyanate end groups. Therefore, FGEW = 3000/6 = 500.
Method 2—Per cent charged method
Some condensation and addition reactions create polymers where not all RFGs along the backbone of the polymer are consumed during the reaction, so an accurate FGEW cannot be determined through a simple end-group analysis.
In many of these cases, calculating the FGEW may be more complex. For example, in some condensation and addition reactions, some RFGs along the polymer backbone are unchanged during polymerisation. Also, in some cases, the structural formula of the final polymer is not accurately known.
In these cases, FGEW can be calculated according to Equation 2 or 3, using the weight percentage monomer in the polymer (W), the formula weight of the monomer (FW) and the number of RFGs on the monomer (n).
For example, for an acrylic polymer containing 7.5% acryloyl chloride monomer (FW 90.5), the FGEW of acid chloride groups in the polymer is:
If the various RFGs in a polymer arise from multiple monomers, the following equation can be used:
Where FGEWn is the FGEW for each functional group in the polymer.
- Consider the reaction between ethanediamine (MW 60) (charged at 30%) and diglycidyl ether (MW 130) (70%) to give a polymer of NAMW 5000. The epoxides in the backbone are reacted to give an aliphatic alcohol (low concern). The amine groups remain intact, with their FGEW proportional to the charged amount of ethanediamine. As the diglycidyl ether is in excess, it can be assumed that the polymer is epoxide-terminated.
Using equation 2, the FGEW for the amine group is (100 x 60)/(30 x 2) = 100. The FGEW for the epoxide group can be calculated using end group analysis (Equation 1), that is, 5000/2 = 2500.
Then, using equation 3, FGEWcomb = inverse of [1/100 + 1/2500] = 96.
- Consider a p-cresol-formaldehyde condensation polymer which is reacted with 1.5% epichlorhydrin to give an epoxide-capped resin. As a worst-case scenario, it is assumed that the polymer is phenol-terminated and that epoxy rings from the epichlorhydrin (MW 92.5, 1 epoxy group) are also present. A NAMW of 10 000 is assumed.
Using equation 2, the FGEW for the epoxide group is (100 x 92.5)/(1.5 x 1) = 6167. The FGEW for the phenol group can be calculated using end group analysis (Equation 1), that is, 10 000/2 = 5000.
Then, using equation 3, FGEWcomb = inverse of [1/6167 + 1/5000] = 2762.
- Consider the addition reaction involving the polymerisation of three acrylates, glycidyl methacrylate (10%, MW 142, 1 RFG), hydroxymethyl acrylamide (2%, MW 101, 1 RFG) and acrylic acid (88%).
In this case, it can be assumed that each monomer is completely incorporated into the polymer, with the RFGs of concern being the epoxide group from glycidyl methacrylate and the hydroxymethyl amide group from the acrylamide. The carboxylic acid moiety from acrylic acid is of low concern and need not be included in FGEW calculations.
Using equation 2, the FGEW for the epoxide group is (100 x 142)/(10 x 1) = 1420. Again using equation 2, the FGEW for the hydroxymethyl amide group is (100 x 101)/(2 x 1) = 5050.
Then, using equation 3, FGEWcomb = inverse of [1/1420 + 1/5050] = 1108.
Unless a new polymer is a polyester manufactured from the list of allowable reactants, the NAMW of a PLC must be 1000 Da or greater (see: polyesters). A PLC must also meet the percentage of low molecular weight species requirements.
For the purposes of the Act, the low molecular weight species in a polymer includes the oligomer content with NAMW <1000 Da, where oligomer is defined as the low molecular weight species derived from the polymerisation reaction.
This definition is consistent with that used by the US EPA in its polymer exemption criteria. It means that residual monomers and other reactants are not included when determining the content of low molecular weight species.
For polymers with an NAMW between 1000 and 10000, the allowable low molecular weight species is 10% under 500; and 25% under 1000, provided that the polymer contains:
- only low concern RFGs;
- moderate concern RFGs with a combined FGEW of 1000 or more (provided no high concern groups are present); or
- high concern RFGs with a combined FGEW of 5000 or more (the calculated FGEW must include moderate concern groups if present).
For polymers with an NAMW >10000, the allowable low molecular weight species is 2% under 500; and 5% under 1000. There is no limit on the number of RFGs in a polymer with an NAMW >10000.
1. Consider a polymer of NAMW 8000, 15%
Is the polymer a PLC? First, it meets the molecular weight criteria. The FGEW is 8000/2 = 4000. As the RFGs are in the high concern category, the polymer does not meet the criterion as the FGEW is below 5000. Therefore, the polymer is not a PLC.
2. Consider a polymer of NAMW 18000, 15%
Is the polymer a PLC? First, there is no restriction on RFGs so the number of epoxide groups does not matter. However, as the polymer does not satisfy the criterion for low molecular weight species, it is not a PLC.
To be eligible as a PLC, a polymer must have a low charge, or cationic, density.
Cationic polymers and polymers reasonably anticipated to become cationic in a natural aquatic environment are not eligible as PLCs. The main concern is their toxicity towards aquatic organisms such as fish and algae.
For the purposes of legislation, and this guidance, these definitions apply:
- A polymer is a low charge density polymer if it is:
- not a cationic polymer or is not reasonably anticipated to become a cationic polymer in a natural aquatic environment (4<pH<9), or
- a solid material that is not soluble or dispersible in water and will only be used in the solid phase (for example ion exchange beads), or
- cationic (or potentially cationic) and the combined (total) FGEW of cationic groups is 5000 or above (see: How to calculate functional group equivalent weight).
- A cationic polymer is a polymer containing a net positively-charged atom/s or associated group/s of atoms covalently linked to its polymer molecule. Examples are the ammonium, phosphonium and sulfonium cations.
- A potentially cationic polymer is a polymer containing groups reasonably anticipated to become cationic. Examples are all amines (primary, secondary, tertiary, aromatic, etc.) and all isocyanates (which hydrolyse to form carbamic acids, then decarboxylate to form amines).
- Reasonably anticipated means aknowledgeable person would expect a given physical or chemical composition or characteristic to occur, based on factors such as the nature of the precursors used to manufacture the polymer, the type of reaction, the type of manufacturing process, the products produced in the polymerisation, the intended uses of the substance and associated use conditions.
Consider a polyamide of NAMW 7000 manufactured from equimolar amounts of ethanediamine and isophthalic acid.
On average, the polymer will have one unreacted amino group at one end of the polymer chain and an unreacted carboxylic acid group at the other end. The amino group is potentially cationic so—as FGEW is defined as the ratio of the NAMW to the number of RFGs—the FGEW for the amino group is 7000/1.
Therefore, the polymer meets the criteria for low charge density as the FGEW is above 5000. If the NAMW had been <5000, or if the polymer had two free amine groups, then the polymer would not be eligible as a PLC.
- A polymer is a low charge density polymer if it is:
A polymer can only be a PLC if it is not classified as a hazardous chemical (see: Glossary for definition).
A PLC must contain, as an integral part of its composition, at least two of the atomic elements carbon, hydrogen, nitrogen, oxygen, silicon and sulphur.
Excluding impurities, a PLC must only contain the following:
- carbon,hydrogen, nitrogen, oxygen, silicon and sulphur
- sodium,magnesium, aluminium, potassium, calcium, chlorine, bromine and iodine as the monatomic counter-ions Na+, Mg2+, Al3+, K+, Ca2+, Cl-, Br- or I-
- fluorine,chlorine, bromine or iodine covalently bound to carbon
- <0.2%(by weight) of any combination of the atomic elements lithium, boron, phosphorus, titanium, manganese, iron, nickel, copper, zinc, tin and zirconium.
No other elements are allowed, except as impurities. Specifically, the fluoride anion F- is not allowed as it has a high acute toxicity.
This requirement refers to monatomic species only. For example, a polymer containing the ammonium counter ion may be a PLC provided it meets the other PLC criteria.
Regarding the binding of halogens to carbon, it should be noted that the perchlorate anion ClO4- would not be allowed because the chlorine is not covalently bound to carbon, but the trichloroacetate anion CCl3CO2- would be allowed.
Degradable or unstable polymers
A PLC must be a stable polymer.
A polymer is not eligible to be a PLC if it is designed or reasonably anticipated to degrade, decompose or depolymerise substantially. This includes polymers that could substantially decompose after manufacture and use, even though they are not intended to do so.
For the purposes of the legislation and this guidance, this definition applies:
Degradation, decomposition or depolymerisation means a type of chemical change in which a polymeric substance breaks down into simpler, smaller weight substances as the result, for example, of oxidation, hydrolysis, heat, sunlight, attack by solvents or microbial action.
Reasonably anticipated - see Cationic polymers.
Substantially means 'considerably', 'meaningfully' or 'to a significantly large extent'. It is not intended to include the slow, natural biodegradation that occurs during, say, the weathering of paint.
Examples of polymers that would not meet this criterion include those that:
- are designed to be pyrolysed or burnt during normal use
- are explosive
- substantially biodegrade in the environment (for example, starch).
Water absorbing polymers
Water absorbing polymers with NAMW 10000 and greater—meaning a polymer capable of absorbing its own weight in water—do not qualify as PLCs.
This criterion is for water absorbing polymers in particulate form only and is directed towards polymers known as 'super absorbents', such as those used in disposable nappies and paper towels.
The concerns for water absorbing polymers are based on data showing that cancer was observed in a two-year inhalation study in rats on a high molecular weight (HMW) water-absorbing polyacrylate polymer.
Water-soluble and water dispersible polymers are not considered to be water absorbing polymers. Moreover, it is assumed that particles of these polymers are adequately cleared from the lungs by normal mucociliary clearance mechanisms after inhalation.
A polyester is defined as a chemical substance meeting the definition of polymer in the Act with polymer molecules containing at least two carboxylic acid ester linkages, at least one of which links internal monomer units.
Polyesters manufactured from an approved list of monomers or other reactants are eligible for notification as PLCs, provided they satisfy all other PLC criteria. This provision is independent of the NAMW.
The list of approved monomers and other reactants from which polyester may be made is in the table below.
A number of reactants on this list are not on the Australian Inventory of Chemical Substances (AICS). Therefore, the manufacture of polyesters from these reactants cannot be carried out in Australia without notification to and assessment of the reactants by NICNAS.
On the other hand, polyesters manufactured from these reactants overseas could be imported, as the reactant itself would not be introduced.
Note: Polyesters manufactured from the anhydride of an acid on the polyester list—for example, succinic anhydride (butanedioic acid)—are allowed, provided there are no pendant anhydrides in the polymer.
In summary, certain polyesters will not be eligible for notification as PLCs, including:
- biodegradable polyesters, which do not meet the degradation criterion
- water-absorbing polyesters
- polyesters manufactured from any monomer or other reactant not on the list of allowable reactants, including such a reactant at <2%.
List of approved monomers and other reactants from which polyesters may be made
Monobasic acids and natural oils
Fats and glyceridic oils, anchovy
Fats and glyceridic oils, babassu
Fats and glyceridic oils, herring
Fats and glyceridic oils, menhaden
Fats and glyceridic oils, sardine
Fats and glyceridic oils, oiticica
Fatty acids, C16-18 and C18-unsaturated
Fatty acids, castor-oil
Fatty acids, coco
Fatty acids, dehydrated castor-oil
Fatty acids, linseed oil
Fatty acids, safflower oil
Fatty acids, soya
Fatty acids, sunflower oil
Fatty acids, sunflower-oil, conjugated
Fatty acids, tall-oil
Fatty acids, tall-oil, conjugated*
Fatty acids, vegetable oil
Glycerides, C16-18 and C18-unsaturated
Hexanoic acid, 3,3,5-trimethyl-
Linseed oil, oxidized
Oils, palm kernel
Di and tri basic acids
1,3-Benzenedicarboxylic acid, dimethyl ester
1,4-Benzenedicarboxylic acid, diethyl ester
1,4-Benzenedicarboxylic acid, dimethyl ester
Butanedioic acid, diethyl ester
Butanedioic acid, dimethyl ester
2-Butenedioic acid (E)-
Decanedioic acid, diethyl ester
Decanedioic acid, dimethyl ester
Fatty acids, C18-unsaturated, dimers
Heptanedioic acid, dimethyl ester
Hexanedioic acid, dimethyl ester
Hexanedioic acid, diethyl ester
Nonanedioic acid, dimethyl ester
Nonanedioic acid, diethyl ester
Octanedioic acid, dimethyl ester
Pentanedioic acid, dimethyl ester
Pentanedioic acid, diethyl ester
2-Propen-1-ol, polymer with ethenylbenzene
Acetic acid, 2,2´-oxybis-
Cyclohexanol, 4,4´-(1-methylethylidene) bis
Methanol, hydrolysis products with trichlorohexylsilane and trichlorophenylsilane
Phenol, 4,4´-(1-methylethylidene)bis-, polymer with 2,2´-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bis[oxirane]
Siloxanes and Silicones, dimethyl, diphenyl, polymers with phenyl silsesquioxanes, methoxy-terminated
Siloxanes and Silicones, dimethyl, methoxy phenyl, polymers with phenyl silsesquioxanes, methoxy-terminated
Siloxanes and Silicones, methyl phenyl, methoxy phenyl, polymers with phenyl silsesquioxanes, methoxy- and phenyl-terminated
Silsesquioxanes, phenyl propyl
*Designates chemical substance of unknown or variable composition, complex reaction products, and biological materials (UVCB substances). The CAS Registry Numbers for UVCB substances are not used in chemical abstracts and its indexes.
**1-Butanol may not be used in a substance manufactured from fumaric or maleic acid because of potential risks associated with esters which may be formed by reaction of these reactants.
Last update 29 July 2018