Following on from last week’s email, when we looked at the relationship between Transport of Dangerous Goods (TDG) and CLP, which you can find here, this week, we’ll look at how they are different.
As we discussed last week, TDG focusses on physical hazards and higher level and immediate health hazards, because it’s designed for people transporting and storing dangerous goods, and for emergency responders in a transport incident involving chemicals. Transport personnel are unlikely to be exposed to chemicals directly unless there is an accident or spillage.
CLP does include most transport hazards (except radioactives and biological hazards) and it is also interested in lower level health hazards which don’t appear in TDG, and long term exposure hazards such as carcinogenicity, mutagenicity and reproductive toxicity. This is because it is designed to provide hazard information for people who’re actually going to use the product, and potentially be exposed to it in their day to day work.
We have made the diagram, above, to show the differences between GHS and TDG, based on the GHS hazard statement codes (This is based on information in Annex 1 of GHS, which gives the equivalent TDG and GHS hazard statement codes).
(Note that this is to Revision 7 of GHS, not Revision 8. If you’d like a copy of this diagram as a pdf, please email me).
Having explained how TDG and CLP are related, and what the hazards are which they have in common, it’s also important to understand that the two systems do vary in a several significant ways:
- some CLP hazards don’t exist in TDG, which can cause confusion
- certain CLP hazards attract a symbol when they don’t under TDG, and vice versa
- the classification method is different between CLP and TDG
- labelling is required on different packages and chemicals in bulk
- labelling information and appearance is significantly different between the two systems
Some CLP hazards don’t exist in TDG
This might seem an obvious statement to make, given that the infographic above shows that quite a few hazards exist in CLP but not in TDG, yet not everybody is aware of that fact.
It is perfectly possible for a product to be classified for CLP, and not to be classified under TDG. Just because something is classified for CLP does not mean it is classified for TDG, and it does not necessarily need a UN number and hazard symbol. (I’m including this fact because one of my clients rang me in a panic recently, having been asked for a UN number for something which is only classified for CLP!).
Having said that, if a product is classified for a chemical hazard for Transport, (excluding radioactives and biological hazards), it is highly likely that it will be classified for CLP.
Confusion between CLP and TDG symbols
The confusion between CLP and TDG is less than it was under CHIP, which is good, because under CHIP, R10 Flammable materials didn’t attract the “flame” pictogram, but they did for Transport.
This has now been resolved within GHS and therefore CLP, where Category 3 flammable liquid and vapour (the equivalent of R10 under CHIP) does have the “flame symbol”, so the Transport and Supply symbols are the same.
Unfortunately, serious eye damage 1, H318 in GHS (and CLP), and corrosive to metals, H290, both attract the “corrosive” symbol, but they don’t in TDG, where eye effects are not included.
Because the corrosive symbol is the same for serious eye damage as for skin corrosion, it can look like a package labelled for eye damage for supply has had the corrosive symbol missed off for TDG, in situations where a dual CLP-Transport label is placed on a drum, or there is a clear shrink wrap showing a supply label beneath a Transport outer label.
Some GHS lower level environmental hazards, H412 and H413, which don’t attract the environment symbol for GHS, do have the environment symbol for Transport.
Differences in Classification methods of CLP and TDG
There is a certain similarity between CLP and TDG classification, in that they both have a list of “approved” classifications to be used, as well as methods for classifying on the basis of test data and thresholds.
However, the list of “approved” classifications is quite different between the two systems, as they can cover different materials, and can also have different classification outcomes.
This means that you can’t always translate easily between the two systems, although looking at the classifications can give you an idea of how a product should be classified, at least for the hazards which they have in common.
Labelling can be required on different packaging layers and for bulk chemicals
Transport labels are generally required for the outer package of goods, for example the outside layer of a pallet containing boxes or bottles, but GHS and CLP require each individual package to be labelled, and inner and outer boxes and packages to be labelled as well (there are some specific rules which apply).
Bulk chemicals in storage on site are required to be stored according to individual country requirements (in the UK, this is the signs and ?? regulation), which was amended in 2015 to include CLP symbols.
Bulk chemicals in transit do require TDG symbols and other information, such as the UN number, but they do not require CLP symbols or labels, because they are for industrial users and not “for supply” per se, although obviously the CLP classification and labelling information must still be supplied to the end user via the Safety Data Sheet.
Differences in label appearance and content
Labels for TDG generally comprise the symbols, which are coloured diamonds, and numbers numbers (for the Transport Class) on them, and sometimes pictures or symbols (e.g. for radioactivity, or environmental hazard). The UN number is supplied as well, and extra information may be placed on a transport vehicle in the form of a placard.
TDG label information is designed to be understandable by people in many different languages, and also by people who are illiterate, so the text is kept to a minimum.
Labels for CLP comprise symbols (technically called pictograms), which are white diamonds with a red border and a black pictogram in the middle. There is a lot of text on the CLP label, such as the product identifiers (chemical name, or trade name of a mixture), Signal Word, Hazard Statements, Precautionary Statements and supplementary information, not forgetting the supplier name, address and contact telephone number. Hazardous mixtures may also have the UFI number.
The symbol size is much larger in transport, 10cm/ 100mm along each diagonal, but CLP pictograms are much smaller, and the size of pictogram reduces as the package gets smaller.
It is possible to have dual Transport-CLP labels, as we used to have under CHIP, where the information is placed side by side, e.g. on large single package such as a drum or IBC.
In this situation, it is permissible to omit the CLP symbols which are already given for Transport, although, given the differences in audience for Transport and Supply labels, this can potentially cause confusion, and should be used with caution.
I hope that this two-part overview of the two systems of Transport of Dangerous Goods and CLP-GHS is useful.
GHS Classification Courses from TT Environmental Ltd
18th November 2019
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