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REACH

Authorisation

g) Technical instructions for specific Annex XIV entries

Can an application for authorisation for chromium trioxide cover the use of the chromic acids and their oligomers generated from adding chromium trioxide to water?

Yes. The reasoning and some example are provided below.

When brought in contact with water, chromium trioxide (EC number 215-607-8) forms two acids and several oligomers: Chromic acid (EC number 231-801-5), Dichromic acid (EC number 236-881-5), Oligomers of chromic acid and dichromic acid (further referred as "Chromic acids and their oligomers"). These chemical species are all identified as substances of very high concern (SVHC) and included in Annex XIV1 as two separate entries. Latest Application Date (21 March 2016) and Sunset Date (21 September 2017) are identical for both entries.

Chromic acids and their oligomers generated in water from chromium trioxide are commonly referred to as an aqueous solution of chromium trioxide. With regard to the authorisation requirements, it may be justifiable in some situations to consider for practical reasons chromic acids and their oligomers as an aqueous solution of chromium trioxide.

The generation of chromic acids and their oligomers by adding chromium trioxide to water is a use of a substance under REACH. This may be a discreet use of chromium oxide by a formulator or part of an integrated process in the use of chromium oxide. Considering this in the context of applications for authorisation, this operation should be considered as a "use applied for" and be addressed in the chemical safety report (CSR), the analysis of alternatives and, if appropriate, in the socio-economic analysis. Hence, applications for authorisation that are meant to cover further uses down the supply chain after the initial step in which chromium trioxide is brought in contact with water, have to refer to the chromic acids and their oligomers.

This answer is strictly limited to chromium trioxide and chromic acids and their oligomers generated from chromium trioxide in water. The system in aqueous solution is a complex equilibrium between multiple chemical species which depends on several physico-chemical parameters and the different chemical species cannot be isolated from the aqueous solution. The answer should thus not be applied by analogy to any other substance.

The table below describes possible scenarios in the case of an application for authorisation is made by the manufacturer/importer/user of chromium trioxide and/or chromic acids and their oligomers. Technical instructions are provided in the last column of the table.

As a general rule, sections 1.1, 1.2 and 1.3 of IUCLID should always refer to the substance applied for (i.e. the substance indicated in the third column - "Application for authorisation" of Table 1). In addition, if there is more than one substance which is imported/used (scenario #2 below) or if the substance actually imported/used is different from the substance applied for (scenario #3b below) this information should be described in section 1.2.

For each use, the assessment performed in the assessment reports (CSR, analysis of alternatives (AoA) and socio-economic analysis (SEA)) should relate to the substance relevant for that use. The substance at the use level (e.g. chromic acids and their oligomers - used in electroplating) might indeed differ from the substance applied for (e.g. chromium trioxide) in terms of hazard, physical form / potential for exposure to Cr(VI), alternatives, etc.

Table 1 - Possible scenarios in the case of an application made by the manufacturer/importer of chromium trioxide and/or chromic acids and their oligomers2

 

Scenario # Actor / Scenario Application for authorisation Explanation / Technical instructions
1 Manufacturer / importer/User of chromium trioxide who generates chromic acids and their oligomers in water applies for an authorisation for this use and the further uses of chromic acids and their oligomers (by itself and/or its downstream users) One application for authorisation for chromium trioxide covering the further uses of the chromic acids and their oligomers Substance ID in IUCLID
  • Section 1.1:indicate chromium trioxide as reference substance
  • Section 1.2: describe the actual composition of chromium trioxide
  • Section 1.3: indicate the A.XIV entry 16 (entry number for chromium trioxide)
Assessment reports in IUCLID (CSR, AoA, SEA):
  • Assessment to be based on the relevant substance per use (chromium trioxide or chromic acids and their oligomers). The two substances may differ e.g. in terms of hazard, form / potential for exposure to Cr(VI), alternatives etc.
2

Importer/User of both
- chromium trioxide
and
- chromic acids and their oligomers generated in water from chromium trioxide

applies for an authorisation for the generation in water  of chromic acids and their oligomers and their further uses (by itself  and/or its downstream users)
 

One application for authorisation for chromium trioxide covering the further uses of the chromic acids and their oligomers

The application should be made for chromium trioxide making clear that chromic acids and their oligomers are also imported/used.

Substance ID in IUCLID:

  • Section 1.1: indicate chromium trioxide as reference substance
  • Section 1.2: describe as first composition the actual composition of chromium trioxide and as second composition the actual composition of chromic acids and their oligomers. In addition, indicate in the "brief description" field that both chromium trioxide and chromic acids and their oligomers are imported/used.
  • Section 1.3: indicate the A.XIV entry 16 (entry number for chromium trioxide)

Assessment reports in IUCLID (CSR, AoA, SEA):

  • Assessment to be based on the relevant substance per use (chromium trioxide or chromic acids and their oligomers). The two substances may differ e.g. in terms of hazard, form / potential for exposure to Cr(VI), alternatives etc.
3 Importer/User of chromic acids and their oligomers generated in water from chromium trioxide applies for an authorisation for the further uses of chromic acids and their oligomers (by itself and/or its downstream users) One application for authorisation either for
  1. chromic acids and their oligomers generated from chromium trioxide covering the further uses
  2. or for
  3. chromium trioxide covering the further uses of chromic acids and their oligomers

In case the importer/user decides to apply for an authorisation for chromic acids and their oligomers in an application for chromium trioxide (case b), it has to become clear from the application that what is actually imported/used are chromic acids and their oligomers:

Substance ID in IUCLID:

  • Section 1.1: indicate as reference substance the substance applied for: either chromic acids and their oligomers (case a) or chromium trioxide (case b)
  • Section 1.2:
    • in case a): describe the actual composition of chromic acids and their oligomers
    • in case b): for technical reasons describe as first composition the composition of chromium trioxide (100% purity) and as second composition the actual composition of chromic acids and their oligomers. In addition, indicate in the "brief description" field that what is actually imported/used are chromic acids and their oligomers.
  • Section 1.3 indicate the A.XIV entry of the substance applied for: 17 if applying for the chromic acids and their oligomers (case a) or 16 if applying for chromium trioxide (case b)

Assessment reports in IUCLID (CSR, AoA, SEA):

  • Assessment to be based on chromic acids in terms of e.g. in terms of hazard, form / potential for exposure to Cr(VI), alternatives etc.

 

4 Manufacturer/Importer/User of chromic acids and their oligomers generated by alternative methods other than from adding chromium trioxide to water3
or
Importer/User who is unaware of the manufacturing methods of the chromic acids and their oligomers applies for an authorisation for the further uses of chromic acids and their oligomers (by itself and/or its downstream users)
One application for authorisation for chromic acids and their oligomers covering the further uses

The approaches described above cannot be applied as the starting material for manufacturing chromic acids and their oligomers is not chromium trioxide or is not known.

Substance ID in IUCLID:

  • Sections 1.1: indicate as reference substance: chromic acids and their oligomers
  • Section 1.2: describe the actual composition of chromic acids and their oligomers
  • Section 1.3: indicate the A.XIV entry 17 (entry number for chromic acids and their oligomers)

Assessment reports in IUCLID (CSR, AoA, SEA):

  • Assessment to be based on chromic acids and their oligomers, in terms of e.g. hazard, form / potential for exposure to Cr(VI), alternatives etc.

 

Please see also Q&A=804 (Do chromic acids and their oligomers, generated in water from chromium trioxide, require their own registration under REACH?)

1  Entry#17: 'Acids generated from chromium trioxide and their oligomers. Group containing: chromic acid, dichromic acid, and oligomers of chromic acid and dichromic acid' And Entry#16: 'chromium trioxide'

2  Chromic acids and their oligomers generated from chromium trioxide could be described in IUCLID sections 1.1 and 1.2 e.g. as a UVCB substance with IUPAC name "Acids generated from chromium trioxide and their oligomers" and Brief description "complex composition typically including oligomers of chromic and dichromic acids in equilibrium with each other". As constituents there could be listed i) chromic acid, ii) dichromic acid, and iii) oligomers of chromic and dichromic acids.

3  Further clarification may be needed as to whether alternative methods would lead to similar equilibrium as for aqueous solutions

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