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A Possible Solution on GHS Corrosivity Criteria

December 16th, 2013 Comments off

In an October 15, 2013 post, we described the opinions of UN experts on GHS corrosivity criteria. There were a number of options with various levels of support.

At the 26th session of the UN Sub-Committee of Experts on GHS, which took place December 4-6, 2013, UN experts continued discussions around the topic of corrosivity criteria. The Sub-Committee was informed that the “Joint TDG-GHS Working Group on corrosivity criteria” had reached an agreement on working on a possible solution on the basis of an outline developed by the Netherlands. The Sub-Committee agreed to continue working on the development of a proposal on the basis of the following outline:

  • Retaining the GHS sub-categories 1A, 1B and 1C, as these sub-categories are central to GHS corrosivity classification, and are used to establish workplace standards for storage and safe handling.
  • Confirmation of the correlation between the GHS sub-categories 1A, 1B and 1C with Packing Groups I, II and III respectively where these are based on human, animal or in vitro data. The challenge was in assigning packing groups in the transport sector when the GHS alternative methods, particularly the additivity and non-additivity approaches, were applied. A further challenge lay in identifying additional criteria for when Packing Group I should be assigned for substances and mixtures classified as GHS sub-category 1A and not included in the Dangerous Goods List.

Here is a summary of the outline from which a proposal will be developed:

A Possible Solution on GHS Corrosivity Criteria

Source: Outcome of the meeting of the joint TDG-GHS working group on corrosivity criteria, page 2.

The Sub-Committee also agreed to request the TDG Sub-Committee to consider mechanisms to address the issue outlined in the first row of the table, i.e. developing a mechanism to assign substances to Packing Group I for transport purposes on the basis of considerations that could go beyond hazard classification.
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Opinions of UN Experts on GHS Corrosivity Criteria

October 15th, 2013 Comments off

The 25th session of the UN Sub-Committee of Experts on GHS took place July 1-3, 2013. The session included classification criteria and hazard communication on the agenda. Corrosivity criteria were one of the issues discussed by an informal working group.

The report of the session indicates some experts believed that the current classification scheme provided harmonized results for all sectors when based on in vivo data, and that inconsistencies occurred when classification results were derived either from translation of previous classification results into GHS hazard classes/categories or from using alternative classification methods, which usually led to over-classification. Because over-classification of corrosive substances had a direct impact on transport and storage conditions, the working group concluded that the outcomes should not lead to reclassification of Class 8 substances in transport, and should not default to more severe classification or assignment to a more onerous packing group than appropriate.

While some experts considered that deletion of sub-categories 1A, 1B and 1C in the GHS would solve the issue of over-classification within Category 1, others thought that sub-categorization was also being used in the workplace to specify appropriate engineering controls or PPE, and therefore considered that they should not be deleted. It was also noted that not all jurisdictions had adopted the sub-categories.

Several experts were in favor of option 6 as the best compromise to address the needs of all sectors (adopt GHS classification criteria in transport, including alternative methods; force alignment of PG I, PG II and PG III with hazard categories 1A, 1B, 1C for animal test data only; for alternative methods apply other criteria to assign PG), and recognized that more work was needed to define the conditions under which alternative methods (including those that did not result in sub-categorization such as pH and non-additivity methods) could be used while ensuring that the results were consistent with the requirements for transport. Option 2 (remove skin corrosion sub-categories 1A, 1B and 1C from the GHS and adopt in transport the GHS criteria as amended; include alternative methods; establish criteria for assignment of PGs I, II and III) and option 5 (adopt in transport GHS classification criteria, including alternative methods; no hazard sub-categories in both GHS and transport; assign PG separately from transport classification) also received support.

Regarding the use of expert judgment and weight of evidence, the group noted that a positive result under human exposure should always supersede the results obtained from test methods, and agreed that the concept of expert judgment needed to be further clarified.

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