Packing group assignment for substances and mixtures
Existing human and animal data including information from single or repeated exposure shall be the first line of evaluation, as they give information directly relevant to effects on the skin.
In assigning the packing group in accordance with 2.2.8.1.4.4, account shall be taken of human experience in instances of accidental exposure. In the absence of human experience the assignment shall be based on data obtained from experiments in accordance with OECD Test Guideline 4045or 4356.Asubstance or mixture which is determined not to be corrosive in accordance with OECD Test Guideline 4307or 4318may be considered not to be corrosive to skin for the purposes of ADR without further testing.
Packing groups are assigned to corrosive substances in accordance with the following criteria (see table 2.2.8.1.5.3):
(a)Packing groupI is assigned to substances that cause irreversible damage of intact skin tissuewithin an observation period up to 60 minutes starting after the exposure time of threeminutes or less;
(b)Packing group II is assigned to substances that cause irreversible damage of intact skin tissuewithin an observation period up to 14 days starting after the exposure time of more than threeminutes but not more than 60 minutes;
(c)Packing group III is assigned to substances that:
(i)Cause irreversible damage of intact skin tissue within an observation period up to 14days starting after the exposure time of more than 60 minutes but not more than 4hours; or
5 OECD Guideline for the testing of chemicals No. 404 "Acute Dermal Irritation/Corrosion" 2015
6 OECD Guideline for the testing of chemicals No. 435 "In Vitro Membrane Barrier Test Method for Skin Corrosion” 2015
7 OECD Guideline for the testing of chemicals No. 430 "In Vitro Skin Corrosion: Transcutaneous Electrical Resistance Test (TER)” 2015
8 OECD Guideline for the testing of chemicals No. 431 "In Vitro Skin Corrosion: Human Skin Model Test" 2015
(ii)Are judged not to cause irreversible damage of intact skin tissue but which exhibit acorrosion rate on either steel or aluminium surfaces exceeding 6.25 mm a year at a testtemperature of 55 °C when tested on both materials. For the purposes of testing steel,type S235JR+CR (1.0037 resp. St 37-2), S275J2G3+CR (1.0144 resp. St 44-3), ISO3574 or Unified Numbering System (UNS) G10200 or a similar type or SAE 1020,and for testing aluminium, non-clad, types 7075–T6 or AZ5GU-T6 shall be used. Anacceptable test is prescribed in the Manual of Tests and Criteria, Part III, Section 37.
NOTE:Where an initial test on either steel or aluminium indicates the substancebeing tested is corrosive the follow up test on the other metal is not required.
Tablo 2.2.8.1.5.3: Table summarizing the criteria in 2.2.8.1.5.3
|
Packing Group |
Exposure Time |
Observation Period |
Effect |
|
I |
≤ 3 min |
≤ 60 min |
Irreversible damage of intact skin |
|
II |
> 3 min ≤ 1 h |
≤ 14 d |
Irreversible damage of intact skin |
|
III |
> 1 h ≤ 4 h |
≤ 14 d |
Irreversible damage of intact skin |
|
III |
– |
– |
Corrosion rate on either steel or aluminium surfacesexceeding 6.25 mm a year at a test temperature of 55ºC when tested on both materials |
Alternative packing group assignment methods for mixtures: Step-wise approach
General provisions
For mixtures it is necessary to obtain or derive information that allows the criteria to be applied to the mixture for the purpose of classification and assignment of packing groups. The approach to classification and assignment of packing groups is tiered, and is dependent upon the amount of information available for the mixture itself, for similar mixtures and/or for its ingredients. The flow chart of Figure 2.2.8.1.6.1 below outlines the process to be followed:
Figure 2.2.8.1.6.1: Step-wise approach to classify and assign packing group of corrosive mixtures
Bridging principles
Where a mixture has not been tested to determine its skin corrosion potential, but there are sufficient data on both the individual ingredients and similar tested mixtures to adequately classify and assign a packing group for the mixture, these data will be used in accordance with the following bridging principles. This ensures that the classification process uses the available data tothe greatest extent possible in characterizing the hazards of the mixture.
(a)Dilution: If a tested mixture is diluted with a diluent which does not meet the criteria for Class8 and does not affect the packing group of other ingredients, then the new diluted mixturemay be assigned to the same packing group as the original tested mixture.
NOTE:In certain cases, diluting a mixture or substance may lead to anincrease in the corrosive properties. If this is the case, this bridging principlecannot be used.
(b)Batching: The skin corrosion potential of a tested production batch of a mixture can beassumed to be substantially equivalent to that of another untested production batch of thesame commercial product when produced by or under the control of the same manufacturer,unless there is reason to believe there is significant variation such that the skin corrosionpotential of the untested batch has changed. If the latter occurs, a new classification isnecessary.
(c)Concentration of mixtures of packing group I: If a tested mixture meeting the criteria forinclusion in packing group I is concentrated, the more concentrated untested mixture may beassigned to packing group I without additional testing.
(d)Interpolation within one packing group: For three mixtures (A, B and C) with identicalingredients, where mixtures A and B have been tested and are in the same skin corrosionpacking group, and where untested mixture C has the same Class 8 ingredients as mixturesA and B but has concentrations of Class 8 ingredients intermediate to the concentrations inmixtures A and B, then mixture C is assumed to be in the same skin corrosion packing groupas A and B.
(e)Substantially similar mixtures: Given the following:
(i)Two mixtures: (A+B) and (C+B);
(ii)The concentration of ingredient B is the same in both mixtures;
(iii)The concentration of ingredient A in mixture (A+B) equals the concentration ofingredient C in mixture (C+B);
(iv)Data on skin corrosion for ingredients A and C are available and substantiallyequivalent, i.e. they are the same skin corrosion packing group and do not affect theskin corrosion potential of B.
If mixture (A+B) or (C+B) is already classified based on test data, then the other mixture may be assigned to the same packing group.
Calculation method based on the classification of the substances
Where a mixture has not been tested to determine its skin corrosion potential, nor is sufficient data available on similar mixtures, the corrosive properties of the substances in the mixture shall be considered to classify and assign a packing group.
Applying the calculation method is only allowed if there are no synergistic effects that make the mixture more corrosive than the sum of its substances. This restriction applies only if packing group II or III would be assigned to the mixture.
When using the calculation method, all Class 8 ingredients present at a concentration of ≥ 1% shall be taken into account, or < 1% if these ingredients are still relevant for classifying the mixture to be corrosive to skin.
To determine whether a mixture containing corrosive substances shall be considered a corrosive mixture and to assign a packing group, the calculation method in the flow chart in Figure 2.2.8.1.6.3 shall be applied.
When a specific concentration limit (SCL) is assigned to a substance following its entry in Table A of Chapter 3.2 or in a special provision, this limit shall be used instead of the generic concentration limits (GCL). This appears where 1% is used in the first step for the assessment of the packing group I substances, and where 5% is used for the other steps respectively in Figure 2.2.8.1.6.3.
For this purpose, the summation formula for each step of the calculation method shall be adapted. This means that, where applicable, the generic concentration limit shall be substituted by the specific concentration limit assigned to the substance(s) (SCLi), and the adapted formula is a weighted average of the different concentration limits assigned to the different substances in the mixture:
Where:
PG xi = concentration of substance 1, 2 …i in the mixture, assigned to packing group x (I, II or III)
GCL = generic concentration limit
SCLi = specific concentration limit assigned to substance i
The criterion for a packing group is fulfilled when the result of the calculation is ≥ 1. The generic concentration limits to be used for the evaluation in each step of the calculation method are those found in Figure 2.2.8.1.6.3.
Examples for the application of the above formula can be found in the note below.
NOTE: Examples for the application of the above formula
Example 1: A mixture contains one corrosive substance in a concentration of 5% assigned to packing group I without a specific concentration limit:
Calculation for packing group I: 
assign to Class 8, packing group I.
Example 2: A mixture contains three substances corrosive to skin; two of them (A and B) have specific concentration limits; for the third one (C) the generic concentration limit applies. The rest of the mixture needs not to be taken into consideration:
|
Substance X in the mixture and its packing group assignment within Class 8 |
Concentration (conc) in the mixture in % |
Specific concentration limit (SCL) for packing group I |
Specific concentration limit (SCL) for packing group II |
Specific concentration limit (SCL) for packing group III |
| A, assigned to packing group I |
3 |
30% |
none | none |
| B, assigned to packing group I |
2 |
20% |
10% |
none |
| C, assigned to packing group III |
10 |
none | none | none |
Calculation for packing group I:
The criterion for packing group I is not fulfilled.
Calculation for packing group II:
The criterion for packing group II is not fulfilled.
Calculation for packing group III:
The criterion for packing group III is fulfilled, the mixture shall be assigned to Class 8, packing group III.
Figure 2.2.8.1.6.3: Calculation method
If substances of Class 8, as a result of admixtures, come into categories of risk different from those to which the substances mentioned by name in Table A of Chapter 3.2 belong, these mixtures or solutions shall be assigned to the entries to which they belong, on the basis of their actual degree of danger.
NOTE: For the classification of solutions and mixtures (such as preparations and wastes), see also 2.1.3.
On the basis of the criteria set out in paragraph 2.2.8.1.6, it may also be determined whether the nature of a solution or mixture mentioned by name or containing a substance mentioned by name is such that the solution or mixture is not subject to the provisions for this class.
NOTE: UN No. 1910 calcium oxide and UN No. 2812 sodium aluminate, listed in the UN Model Regulations, are not subject to the provisions of ADR.