Last reviewed 18 January 2012

In this article Desmond Waight and Phil Todd discuss some of the issues concerning when a change of classification is made. Note however, that this article is not concerned with the change from a classification under the older DSD/DPD system of classification to that under the CLP system.


In an ideal world, a classification would only ever be done once, and never subsequently need to be changed. However, we do not live in an ideal world, as the world we live in is constantly changing. This leads to situations where the classification of a substance, or mixture, or even an article have to be amended. With that classification amendment, there will normally be consequences of one sort or another.

Change affecting supply classification only

When the change of classification only affects the supply classification, such as being considered now with carcinogenic/mutagenic/reprotoxic materials, or known as Harmful under the DPD (Acute Tox. 4 under CLP) rather than an irritant, the changes will often only affect the safety data sheet (SDS) and the label.

Where the label is printed on demand, the change of classification can normally be made fairly quickly on both the SDS and the label, although some consideration will need to be given prior to communication to customers.

Where the labels are not printed on demand, there will need to be a consideration of the timescale for the introduction of revised labels. In addition, consideration will need to be given to the timing of how to coincide the change of the SDS revision being issued, with the changes to the labelling that is seen by recipients.

In terms of the provision of updated SDSs, REACH requires that these are retrospectively provided “without delay” to recipients of the chemical within the last 12 months in the following cases.

  1. As soon as new, presumably stricter Risk Management Measures (RMM) are required, or when new, presumably stricter information on the hazards becomes available.

  2. When an authorisation has been granted or refused.

  3. When a restriction has been imposed (under REACH Annex XVII).

In respect of labelling, CLP requires updating “without undue delay” where the new classification or supplemental labelling requirement is more severe. In other cases, the label needs to be updated by the supplier (which may not be the original — but a distributor) within 18 months of the change of classification. To reflect this, company systems may need to clearly differentiate between a proposal to change and the decision by the company to actually change the classification.

Change affecting supply and transport classification

In many cases, but by no means all, changes to classifications for supply will also mean a change in classification for transport.

This may merely result in a minor change for transport, with no need to change the packaging or the labelling and/or marking, eg a change from Flam. Liquid Cat. 2 to Flam. Liquid Cat. 3, consequent on the results of some actual testing, rather than using the flashpoint of the prime constituent. This may result in the need to reassign to a different UN Number, or change the package. It could however, also offer possibilities to redesign the package. For example, allocation to UN1993 PG III (Flam. Liquid Cat. 3) allows up to 5 litre receptacles in an limited quantity (LQ) package, whereas PG II (Flam. Liquid Cat. 2) only allows up to 1 litre. This can have some benefits for those further down the supply chain.

However, in other cases the change can have more significant “negative” effects. For example, a decision to increase the classification of a chemical for supply to Aquatic Acute Category 1 or Aquatic Chronic 1 or 2 from a lower level of environmental hazard, may not have many consequences for SDS, and may be easy to accommodate in any supply labelling, but can be very significant for transport.

Such an example recently occurred with the increase of environmental classification of heavy fuel oil, making the chemical classifiable as UN3077 or UN3082 (depending on whether the oil involved is solid or liquid (as defined in ADR).

Under the old classification, tankers used did not need to conform to the ADR tanker rules, but would need to under the new classification. Since this could not be achieved quickly, an ADR Multilateral Special Agreement (MSA), M235 was generated by Germany and has been signed by a small number of ADR states, including the UK. This exempts until 1 January 2014 from the need for tanks to comply with ADR Chapters 4.2, 6.8 and 7.4, and requires additional special wording in the transport document. A later MSA, M240, also from Germany (and also signed by the UK), then also exempted from the need for the driver to be specially trained — again subject to additional special wording in the transport document. However, tanker placarding and marking, transport of dangerous goods documentation, etc provisions were not exempted.

Changes apparently affecting transport classification only

While these are perhaps rarer, they can occur. For example, the decision to change to a different UN Number to describe the dangerous goods may be necessary.

As an example of this, many suppliers of liquefied petroleum gas (LPG) fuels in plug-in style aerosol dispensers may initially believe that their goods are classifiable as UN2037 — gas cartridges. However these products usually have a small tube sticking out of the top of the device, which on being depressed, releases the gas. This small tube is thus a release device, and this requires that the product be classified under UN1950, rather than under UN2037. The correct classification is necessary to ensure that correct packaging is specified (UN1950 requires a protective cap, while UN2037 does not). This classification problem stems from the lack of uptake of the UN model regulations' definition for aerosols for the United States domestic regulations (which prohibit gas-only aerosols and thus force producers into thinking of them, incorrectly, as gas cartridges). The Far East suppliers often work to the US definitions and requirements, rather than the European, and this initially often misleads the EU importers.

Such a change will require a change to s.14 of the SDS, although it may not require any change to the package outer markings, since both of these UN numbers have LQ package provisions. A separate change to a database used for the production of transport of dangerous goods documentation also needs to be co-ordinated.

However, many suppliers have included the incorrect UN number on the tin plate printing of the aerosol can itself, and getting this changed is an expensive and time-consuming process.


These suppliers also often seem to have a problem with correct labelling anyway, with one recent example showing a miniature version of the Class 2 diamond rather than the appropriate CHIP symbol (F+) or CLP pictogram (GHS02), and another having the Xn symbol in black on a light blue background — although at least the flame symbol was correctly coloured!

Downstream consequences

Once the above issues have been properly understood and procedures put in place, and have been carried out a few times, they will hopefully become routine and not cause major problems.

However, one still needs to keep a very watchful eye out for downstream consequences (further to any already identified earlier). These will often be issues for users of your products, but may also affect you as the producer.

Some examples that illustrate the sort of issues include the following.

  • Changing a product classification so that the material was now a marine pollutant/environmentally hazardous substance (EHS) meant that the unlined flexible IBC (FIBC) that had been used for shipping was no longer authorised, and a lined FIBC had to be found, which was fairly easy. However, the consequence was that the filling equipment needed to be changed to cope with the liner.

  • A product classification was changed to a category 1B carcinogen. The whole basis of safety of the plant producing it had to be changed to a containment approach, which cost approximately $0.5M.

  • Classification of a product was changed from T to T+. This was not a problem for the site producing it, but the product was then used at a toll manufacturer site. Unfortunately, the toll manufacturer did not have a Seveso registration, so could only store 5 tonnes on site. The problem was that the toll manufacturer used 20 tonnes per week! The solution, until they could submit a Seveso application, was that an “ISO tank” had to be parked at a nearby site that was Seveso-registered, and then shuttled to the toll manufacturer every day, delivering just 5 tonnes, before returning to the Seveso site. This was very disruptive and added significant cost.

But equally, a classification change can have beneficial consequences.

  • A supplier of a critical material to an aeroplane builder had classified the material by analogy. The adopted classification was as self-reactive, requiring temperature control. This meant that the aeroplane builder was unable to set up another production line in a different region of the world — as the classification prevented air shipment of the material. Sea shipment was also not allowed but would have been impractical anyway. After much persuasion, the material was finally tested and the tests showed a much lower risk classification was appropriate. This meant much cheaper packaging, and the ability to ship the product by air, so that the aeroplane builder was able to set up the extra, lower cost production line.


A classification change decision needs to be very well thought about beforehand, and the ramifications on all parties, inclusive of those downstream in the supply chain, need to be fully understood and considered. When the decision to reclassify is then made, this needs to be well communicated and properly implemented. Failures can be quite significant, especially if they are unlucky enough to be brought to light by other events (eg a transport crash), or if consequential opportunities are missed.

Acronyms defined


European Agreement Concerning the International Carriage of Dangerous Goods by Road


Regulation (EC) No. 1272/2008 on classification, labelling and packaging of substances and mixtures, amending and repealing [in June 2015] Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No. 1907/2006


Dangerous Preparations Directive (1999/45/EC)


Dangerous Substances Directive (67/548/EEC) (as implemented in Great Britain by the Chemicals (Hazard Information and Packaging for Supply) Regulations 2009 (SI 2009 No. 716) (CHIP) and by equivalent regulations in Northern Ireland)


Intermediate bulk containers


Flexible Intermediate bulk containers


Registration, Evaluation, Authorisation and restriction of Chemicals Regulation (EC) No. 1907/2006)