Polymers containing isocyanate monomers: Human health tier II assessment

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Preface

This assessment was carried out by staff of the National Industrial Chemicals Notification and Assessment Scheme (NICNAS) using the Inventory Multi-tiered Assessment and Prioritisation (IMAP) framework.

The IMAP framework addresses the human health and environmental impacts of previously unassessed industrial chemicals listed on the Australian Inventory of Chemical Substances (the Inventory).

The framework was developed with significant input from stakeholders and provides a more rapid, flexible and transparent approach for the assessment of chemicals listed on the Inventory.

Stage One of the implementation of this framework, which lasted four years from 1 July 2012, examined 3000 chemicals meeting characteristics identified by stakeholders as needing priority assessment. This included chemicals for which NICNAS already held exposure information, chemicals identified as a concern or for which regulatory action had been taken overseas, and chemicals detected in international studies analysing chemicals present in babies’ umbilical cord blood.

Stage Two of IMAP began in July 2016. We are continuing to assess chemicals on the Inventory, including chemicals identified as a concern for which action has been taken overseas and chemicals that can be rapidly identified and assessed by using Stage One information. We are also continuing to publish information for chemicals on the Inventory that pose a low risk to human health or the environment or both. This work provides efficiencies and enables us to identify higher risk chemicals requiring assessment.

The IMAP framework is a science and risk-based model designed to align the assessment effort with the human health and environmental impacts of chemicals. It has three tiers of assessment, with the assessment effort increasing with each tier. The Tier I assessment is a high throughput approach using tabulated electronic data. The Tier II assessment is an evaluation of risk on a substance-by-substance or chemical category-by-category basis. Tier III assessments are conducted to address specific concerns that could not be resolved during the Tier II assessment.

These assessments are carried out by staff employed by the Australian Government Department of Health and the Australian Government Department of the Environment and Energy. The human health and environment risk assessments are conducted and published separately, using information available at the time, and may be undertaken at different tiers.

This chemical or group of chemicals are being assessed at Tier II because the Tier I assessment indicated that it needed further investigation.

For more detail on this program please visit: www.nicnas.gov.au

Disclaimer

NICNAS has made every effort to assure the quality of information available in this report. However, before relying on it for a specific purpose, users should obtain advice relevant to their particular circumstances. This report has been prepared by NICNAS using a range of sources, including information from databases maintained by third parties, which include data supplied by industry. NICNAS has not verified and cannot guarantee the correctness of all information obtained from those databases. Reproduction or further distribution of this information may be subject to copyright protection. Use of this information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner. NICNAS does not take any responsibility whatsoever for any copyright or other infringements that may be caused by using this information.

Acronyms & Abbreviations

The chemicals covered by this assessment are polymers based on isocyanate monomers (i.e. polyurethanes) listed in Stage One of the Inventory Multi-tiered Assessment and Prioritisation (IMAP) program previously published in 2013. During the pre-prioritisation work being conducted in Stage Two of IMAP (NICNAS, 2017), a number of polyurethanes were additionally identified from the Inventory and included in this assessment.

The production of polyurethanes involves the use of an excess of the hydroxyl group-containing monomer or monomers leading to complete reaction of all of the isocyanate groups in a range of generally diisocyanate monomers. The American Chemistry Council (ACC) indicated that “there are no reactive isocyanate groups in a fully reacted diisocyanate-based polymer” (ACC, 2004; US EPA, 2005).

Polyurethane polymers are generally of low concern to human health. However, in the majority of cases, it is not possible to conclude from the chemical name of the polymer whether an individual polyurethane polymer has fully reacted isocyanate groups and can be regarded as of low concern. Some polyurethanes in this assessment have been identified as containing free isocyanate groups (Galleria Chemica).

Finished polyurethane polymers used in the majority of household applications contain no unreacted isocyanate groups. For certain applications, however, similar polymer chemistry can be used with an excess of the isocyanate group-containing monomer. These polymers are isocyanate-terminated, making the isocyanate functional groups reactive with polyols or other substances. This results in the formation of a polyurethane pre-polymer, which is intended to be further reacted in its end use. Where the pre-polymer is identified as being 'blocked', it indicates that there are no free isocyanate groups.

Polymers which may have degradation products of concern such as nonylphenols or bisphenol A are not included in this assessment as the degradants may potentially have additional risks to human health.

Import, Manufacture and Use

Australian

One polymer in this group has reported Australian commercial use including as a construction material additive as reported under previous mandatory and/or voluntary calls for information.

International

The following international uses have been identified through Galleria Chemica, the United States (US) Household Products Database, the Substances in Preparations in Nordic Countries (SPIN) database, US Environmental Protection Agency (EPA) isocyanate profile (US EPA, 2005), and the Safe Work Australia exposure documentation for isocyanates (SWAa).

Some polymers in this group have reported domestic use including in paints, lacquers and varnishes.

Some polymers in this group have reported commercial uses including:

  • as reprographic agents;
  • in automotive refinishing; and
  • in adhesive and binding agents.

Some polymers in this group have reported site-limited uses including:

  • as intermediates;
  • in plastics manufacture; and
  • as polyurethane pre-polymers.

Restrictions

Australian

Where the polymers in this group contain free isocyanate groups, these polymers may be covered by the entry for 'Isocyanates', listed in the Poisons Standard—the Standard for the Uniform Scheduling of Medicines and Poisons (SUSMP) in Schedule 6 (SUSMP, 2018) as:

Schedule 6 (Poison)

"ISOCYANATES, free organic, boiling below 300 °C, except in:

a) viscous polyurethane adhesives; or

b) viscous polyurethane sealants;
containing not more than 0.7 per cent of free organic isocyanates boiling below 300 °C."

Schedule 6 chemicals are described as 'Substances with a moderate potential for causing harm, the extent of which can be reduced through the use of distinctive packaging with strong warnings and safety directions on the label'.  Schedule 6 chemicals are labelled with 'Poison' (SUSMP, 2018).

Where the polymers in this group contain free isocyanate groups, these chemicals are covered by the entry for 'Isocyanates', listed in the Safe Work Australia, Model Work Health and Safety Regulations, Hazardous Chemicals (other than lead) requiring health monitoring (SWA, 2016).

International

No known restrictions have been identified.

Existing Work Health and Safety Controls

Hazard Classification

The chemicals are not listed on the Hazardous Chemical Information System (HCIS) (SWAb).

Exposure Standards

Australian

There are no Australian exposure standards for individual polyurethanes in this group.

Safe Work Australia has a group entry for all isocyanates. Where the polymers in this group contain free isocyanate groups, exposure standards of 0.02 mg/m³ time weighted average (TWA) and 0.07 mg/m³ short term exposure limit (STEL) apply.

International

There are no international exposure standards for individual polyurethanes in this group.

Health Hazard Information

Where the polymers in this group are not terminated by free isocyanate groups, no significant health effects are expected.

The free isocyanate group is extremely reactive, and its key health hazards are those identified in the NICNAS assessments of toluene diisocyanates (TDI), methylenediphenyl diisocyanates (MDI), hexamethylene diisocyanate (HDI) and other isocyanates. The common critical health effects for these include acute toxicity via the inhalation route; irritation to skin, eyes and the respiratory system; and sensitisation by inhalation and skin contact, which are well characterised in the IMAP reports published for these chemicals (NICNASa; NICNASb; NICNASc; NICNASd). See www.nicnas.gov.au for more information. Additionally, these common critical health effects have been similarly reported in the exposure standard documentation for isocyanates (SWAa) for isocyanate pre-polymers which may contain TDI, MDI and HDI or other isocyanate monomers.

Pre-polymers with TDI, MDI and HDI contain less than 0.7 % residual monomer (SWAa) and are reportedly stable over time. No residual functional isocyanate groups are present in fully cured polyurethane (ACC, 2004; US EPA, 2005; 3M, 2008). While some polyurethanes in this group may be terminated with isocyanate functional groups, these are not expected to convert back to TDI, MDI or HDI.

Risk Characterisation

Critical Health Effects

If the polymers in this group do not contain free isocyanate groups, none of the polymers are expected to have significant health effects.

However, where the polymers in this group contain free isocyanate groups, the critical health effect for risk characterisation is respiratory sensitisation. Other health effects include systemic acute effect (acute toxicity by the inhalation route of exposure) and local effects (skin sensitisation and respiratory irritation). The polymers may also cause skin and eye irritation.

Public Risk Characterisation

The uses of these polymers are not well known. Some polymers are known to be used commercially in construction in Australia and domestically overseas. Potential domestic uses are limited to paints, varnishes and lacquers, which may involve isocyanate pre-polymers.

Companies using or marketing the polymers in this group will have sufficient information available to determine whether the polymer contains free isocyanate groups. If the polymers do contain free isocyanate groups, particularly if they are low molecular weight pre-polymers, the companies using or marketing these polymers have a responsibility to ensure that they are controlled in accordance with the SUSMP and HSIS requirements.

Polymers containing free isocyanate groups are covered by the current listing on Schedule 6 of the SUSMP provided they meet the boiling point criterion. Strong warning statements, safety directions and first aid instructions apply to any domestic products containing chemicals covered in this assessment. The current controls are considered adequate to minimise the risk to public health posed by any domestic use of these chemicals. Therefore, the risk to public health is not considered to be unreasonable.

Occupational Risk Characterisation

During product formulation, dermal, ocular and inhalation exposure of workers to the chemicals of this group may occur, particularly where manual or open processes are used. These may include transfer and blending activities, quality control analysis, and cleaning and maintenance of equipment. Worker exposure to the chemical at lower concentrations may also occur while using formulated products containing the chemical. The level and route of exposure will vary depending on the method of application and work practices employed.

Where the polymers in this group contain free isocyanate groups, given the critical health effects, the chemicals may pose an unreasonable risk to workers unless adequate control measures to minimise dermal, ocular and inhalation exposure to the chemical are implemented. The chemicals should be appropriately classified and labelled to ensure that a person conducting a business or undertaking (PCBU), e.g. employer, at a workplace, has adequate information to determine appropriate controls.

NICNAS Recommendation

Assessment of the chemicals of this group is considered to be sufficient, provided that the appropriate classification is applied by the PCBU, and labelling and all other requirements are met under workplace health and safety and poisons legislation as adopted by the relevant state or territory.

Companies using or marketing these polymers should seek sufficient information to determine whether the polymer contains free isocyanate groups.

Regulatory Control

Work Health and Safety

Where the polymers in this group contain a free isocyanate group, these are recommended for classification and labelling aligned with the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) as below. In general, for those chemicals with a free isocyanate group that do not have a specific hazard classification on HCIS, the following recommendation could also apply. This does not consider classification of physical hazards and environmental hazards.

From 1 January 2017, under the model Work Health and Safety Regulations, chemicals are no longer to be classified under the Approved Criteria for Classifying Hazardous Substances system.

The recommended classification and labelling entry should have the following note appended against the individual CAS numbers of the polymers: "Note 15: This chemical is a polymer. The hazards of a polymer may depend on a number of factors. For more information refer to the assessment report published on the website of the National Industrial Chemical Notification and Assessment Scheme." The assessment reports referred to in the note are those cited above (NICNASa; NICNASb; NICNASc; NICNASd) and this assessment report.

Hazard Approved Criteria (HSIS)a GHS Classificationb
Acute Toxicity Not Applicable Fatal if inhaled - Cat. 2 (H330)
Irritation / Corrosivity Not Applicable Causes serious eye irritation - Cat. 2A (H319) 
Causes skin irritation - Cat. 2 (H315) 
May cause respiratory irritation - Specific target organ tox, single exp Cat. 3 (H335)
Sensitisation Not Applicable May cause allergy or asthma symptoms or breathing difficulties if inhaled - Cat. 1 (H334) 
May cause an allergic skin reaction - Cat. 1 (H317)

a Approved Criteria for Classifying Hazardous Substances [NOHSC:1008(2004)].

b Globally Harmonized System of Classification and Labelling of Chemicals (GHS) United Nations, 2009. Third Edition.

Public health

Products containing the polymers in this group with a free isocyanate group should be labelled in accordance with state and territory legislation (SUSMP, 2018).

Advice for consumers

Products containing the chemicals of this group should be used according to label instructions.

Advice for industry

Control measures

Control measures to minimise the risk from dermal, ocular and inhalation exposure to chemicals of this group with a free isocyanate group should be implemented in accordance with the hierarchy of controls. Approaches to minimise risk include substitution, isolation and engineering controls. Measures required to eliminate or minimise risk arising from storing, handling and using a hazardous chemical depend on the physical form and the manner in which the chemical is used.  Examples of control measures which may minimise the risk include, but are not limited to:

  • using closed systems or isolating operations;
  • using local exhaust ventilation to prevent the chemical from entering the breathing zone of any worker;
    health monitoring for any worker who is at risk of exposure to the chemical if valid techniques are available to monitor the effect on the worker’s health;
  • air monitoring to ensure control measures in place are working effectively and continue to do so;
  • minimising manual processes and work tasks through automating processes;
  • work procedures that minimise splashes and spills;
  • regularly cleaning equipment and work areas; and
  • using protective equipment that is designed, constructed, and operated to ensure that the worker does not come into contact with the chemical.

Guidance on managing risks from hazardous chemicals are provided in the Managing risks of hazardous chemicals in the workplace—Code of practice available on the Safe Work Australia website.

Obligations under workplace health and safety legislation

Information in this report should be taken into account to help meet obligations under workplace health and safety legislation as adopted by the relevant state or territory. This includes, but is not limited to:

  • ensuring that hazardous chemicals are correctly classified and labelled;
  • ensuring that (material) safety data sheets ((M)SDS) containing accurate information about the hazards (relating to both health hazards and physicochemical (physical) hazards) of the chemical are prepared; and
  • managing risks arising from storing, handling and using a hazardous chemical.

Your work health and safety regulator should be contacted for information on the work health and safety laws in your jurisdiction.

Information on how to prepare an (M)SDS and how to label containers of hazardous chemicals are provided in relevant codes of practice such as the Preparation of safety data sheets for hazardous chemicals—Code of practice and Labelling of workplace hazardous chemicals—Code of practice, respectively. These codes of practice are available from the Safe Work Australia website.

A review of the physical hazards of the chemical has not been undertaken as part of this assessment.

References

3M, 2008. 3M TechUpdate – Isocyanates. Accessed February 2018 at multimedia.3m.com/mws/media/777847O/isocyanates-3m-techupdate.pdf

American Chemistry Council, 2004. Letter from the American Chemistry Council Aliphatic Diisocyanates Panel to EPA’s Information Quality Guidelines Staff, September 8, 2004. Accessed February 2018 at https://www.epa.gov/sites/production/files/2016-03/documents/04025.pdf

Galleria Chemica. Accessed February 2018 at http://jr.chemwatch.net/galeria/

Globally Harmonised System of Classification and Labelling of Chemicals (GHS) United Nations, 2009. Third edition. Accessed at http://www.unece.org/trans/danger/publi/ghs/ghs_rev03/03files_e.html

National Industrial Chemicals Notification and Assessment Scheme (NICNASa). Human health Tier II assessment for hexane, 1,6-diisocyanato-. Australian Government Department of Health and Ageing. Accessed February 2018 at http://www.nicnas.gov.au

National Industrial Chemicals Notification and Assessment Scheme (NICNASb). Human health Tier II assessment for isocyanates. Australian Government Department of Health and Ageing. Accessed February 2018 at http://www.nicnas.gov.au

National Industrial Chemicals Notification and Assessment Scheme (NICNASc). Human health Tier II assessment for methylenediphenyl diisocyanates. Australian Government Department of Health and Ageing. Accessed February 2018 at http://www.nicnas.gov.au

National Industrial Chemicals Notification and Assessment Scheme (NICNASd). Human health Tier II assessment for toluene diisocyanates. Australian Government Department of Health and Ageing. Accessed February 2018 at http://www.nicnas.gov.au/

National Industrial Chemicals Notification and Assessment Scheme, 2017. What is IMAP? Accessed February 2018 at https://www.nicnas.gov.au/chemical-information/imap-assessments/what-is-imap

Safe Work Australia (SWAa). HCIS Exposure Standard Documentation for Isocyanates. Accessed February 2018 at http://hcis.safeworkaustralia.gov.au/ExposureStandards/Document?exposureStandardID=1013

Safe Work Australia (SWAb). Hazardous Chemicals Information System (HCIS). Accessed February 2018 at http://hcis.safeworkaustralia.gov.au/HazardousChemical

Safe Work Australia, 2016. Model Work Health and Safety Regulations. Accessed February 2018 at https://www.safeworkaustralia.gov.au/system/files/documents/1703/model-whs-regulations-28nov2016.pdf

Substances in Preparations in Nordic Countries (SPIN). Accessed May 2013 at http://188.183.47.4/dotnetnuke/Home/tabid/58/Default.aspx

The Poisons Standard, February 2018. The Standard for the Uniform Scheduling of Medicines and Poisons (SUSMP) No. 19. Accessed at https://www.legislation.gov.au/Details/F2018L00043

United States Environment Protection Agency, 2005. Automotive refinishing industry – isocyanate profile. New Chemicals Environmental Technology Initiative, EPA Contract No. 68-D4-0098. May 1997, revised June 2005. Accessed February 2018 at https://www.epa.gov/sites/production/files/2015-06/documents/isocyanate_profile.pdf

US Department of Health and Human Services, Household Products Database (HPD), Health and safety information on household products. Accessed February 2018 at https://hpd.nlm.nih.gov/advancedsearch.htm

Last update 3 January 2019