The following hazard classes make a polymer PRR
• Acute toxicity |
From Acute Tox . 1 to Acute Tox . 4 |
• Germ cell mutagenicity |
Muta . 1A , Muta . 1B or Muta . 2 |
• Carcinogenicity |
Carc . 1A , Carc . 1B or Carc . 2 |
• Reproductive toxicity |
Repr . 1A , Repr . 1B , Repr . 2 or Lact . |
• Aspiration hazard |
Asp . Tox . 1 |
• Respiratory sensitisation |
Resp . Sens . 1 , 1A or 1B |
• Skin sensitisation |
Skin Sens . 1 , 1A or 1B |
• Specific target organ toxicity - single exp . |
STOT SE1 to SE3 |
• Specific target organ toxicity - repeated exp . |
STOT RE 1 and STOT RE 2 |
• Serious eye damage / skin corrosion |
Eye Dam . 1 or Skin Corr . 1 , 1A , 1B or 1C |
• Hazardous to the aquatic environment |
Aquatic Acute 1 , Aquatic Chronic from 1 to 4 |
• Hazardous for the ozone layer |
Ozone |
?
Table 2 – Hazard classes in PRR
In addition , polystyrene standards with dispersity of < 1.2 are typically used to calibrate the GPC . Unfortunately , polystyrene tends to be a very linear polymer . As a standard , it can only be usefully compared with other polymers that are known to be linear and have the same size .
The alternative , Matrix-Assisted Laser Desorption Ionisation Time of Flight ( MALDI-TOF ) mass spectrometry , is a soft ionisation technique that enables the resolution of individual n-mers of polymers in a mass spectrum distribution . This resolution enables the elucidation not only of mass distribution and repeat unit mass , but also the identity and fidelity of end groups for relatively low dispersity polymers ( Đ ≤1.3 ).
The two techniques vary from each other in terms of resolution , potential for estimating low MWs ; solubility or ionisabiity of the sample ; ranges of MWs , the identification of terminal functionalities , time and costs . Deciding which is the best for any given polymer can only be done on a case-by-case basis .
All of the information has to be collected and measured , including the residual monomer content , usually by high-performance liquid chromatography ( HPLC ). However , HPLC does not work for all monomers and this can be a lengthy , expensive process . Thus , in all cases , whether you have to register or not , every company needs to have specific analytical information on all of its polymers and in some cases even some phys-chem properties have to be tested .
Identification & grouping
Broadly speaking , a polymer can only be defined as the same as another if all of the monomers present at > 2 % are the same . However , even this rule is not rigid , because other characteristics also contribute , notably MW , position of functional groups and reaction type .
A new identification method during the notification step is based on defining the polymer based on their MW range , RFG and / or FGEW range , as well as the name of the monomer ( s ). For example ‘ Polymerisation products of hexamethylene diisocyanate reaction products with 2- ( hexyloxy ) ethanol , allophanate , Mn 1000-50000 Da , Isocyanate , FGEW < 1000-10000 Da ’ uses all four .
From ECHA guidance on the grouping of chemicals , the basic principles for forming a group are :
• Grouping hypothesis ( structural similarity , common functional groups , an incremental and constant change across the category , or the same or a similar metabolic pathway )
• Clear identification of the members
• Clear identification of the boundaries
• Data quality and density to justify the boundaries An ECHA workshop held in June 2022 established that the essence of a group is that the ( hazard ) data provided is assumed to be applicable for all individual polymers in the group . However , since grouping is the responsibility of industry , registrants can decide which method or approach is followed in preparing the registration dossier for a group of polymers .
Industry is also responsible for registering their polymers in a way that complies with the grouping criteria and for demonstrating this in the registration dossier . What matters is that the submitted group of individual polymers and the justification both meet clear and objective grouping criteria .
Grouping is primarily based on chemical criteria , where possible complemented with phys-chem data . If hazard data is available prior to registration , this data can be used to justify hazard similarity in the group . Pilot projects have demonstrated that grouping principles differ among types of polymers .
Grouping will be an iterative process . Figure 2 shows the Conceptual Framework for Polymer Risk Assessment ( CF4Polymers ) established in ECETOC Report TR 133-3 and the criteria that can be used .
58 SPECIALITY CHEMICALS MAGAZINE ESTABLISHED 1981