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Diss Factsheets

Administrative data

Description of key information

Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht) has been classified as skin sensitiser for precautionary reasons, based on residual BaP content of <0.1%, compliant with other pitch materials.

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Referenceopen allclose all

Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study based on scientific principles, reproducible test method
Principles of method if other than guideline:
Delayed hypersensitivity/contact sensitisation: Intradermal injection of the agents into the foot pad for induction in the presence of Freund´s adjuvant, followed by topical/epidermal challenge
(method according to: Gell PG and Benacerraf B J. Exp. Med. 113, 571 (1961)
GLP compliance:
no
Type of study:
intracutaneous test
Justification for non-LLNA method:
LLNA test method not available at time of the study
Specific details on test material used for the study:
- Name of test material (as cited in study report): 3,4-benzpyrene (BP)
- Analytical purity: "highly purified" (acc. to report)
Species:
guinea pig
Strain:
Hartley
Sex:
female
Route:
intradermal
Vehicle:
other: emulsion in complete Freund´s adjuvant with saline
Concentration / amount:
125 µg into each front foot pad, total 250 µg
Day(s)/duration:
exposure period 2 - 3 wks
Adequacy of induction:
not specified
No.:
#1
Route:
epicutaneous, open
Vehicle:
other: acetone-olive oil mixture (not further specified)
Concentration / amount:
0.001 %
Day(s)/duration:
24 h
Adequacy of challenge:
not specified
No.:
#2
Route:
epicutaneous, open
Vehicle:
other: acetone-olive oil mixture (not further specified)
Concentration / amount:
0.01 %
Day(s)/duration:
24 h
Adequacy of challenge:
not specified
No.:
#3
Route:
epicutaneous, open
Vehicle:
other: acetone-olive oil mixture (not further specified)
Concentration / amount:
0.1 %
Day(s)/duration:
24 h
Adequacy of challenge:
not specified
No.:
#4
Route:
epicutaneous, open
Vehicle:
other: acetone-olive oil mixture (not further specified)
Concentration / amount:
1 %
Day(s)/duration:
24 h
Adequacy of challenge:
not specified
No. of animals per dose:
6, 16, and 10 were used for 3-methylcholanthrene (MC), BaP and 9,10-dimethyl-1,2-benzanthracene (DMBA), respectively
Details on study design:
RANGE FINDING TESTS: no data

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 1 i.d.
- Exposure period: 2 - 3 weeks
- Test groups: 4
- Control group: 1
- Site: each foot pad
- Frequency of applications: 1x
- Concentrations: 250 µg (125 µg/0.1 mL into each front foot pad)
- Auxiliary agent: emulsion in complete Freund´s adjuvant with saline

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: 2 - 3 weeks after induction
- Exposure period: 24 h
- Test groups: 4
- Control group: 1
- Site: ventral or dorsal shaved skin
- Concentrations: 0.001, 0.01, 0.1,and 1 % (one drop each applied)
- Evaluation (hr after challenge): 24

OTHER:
- Scoring system
according to Gell PG and Benacerraf B J. Exp. Med. 113, 571 (1961): from +++ to 0

Challenge controls:
PAH known to be contact sensitisers in this test system: MC and DMBA
Positive control substance(s):
yes
Remarks:
3- methylcolanthrene (MC) and 9,1-dimethyl-1,2-benzanthracene (DMBA)
Positive control results:
MC +++ (>= 0.1 %); DMBA +++ (1 %).
Dose-related intensity of the responses
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.001%
No. with + reactions:
16
Total no. in group:
16
Clinical observations:
contact reactivity with score +
Remarks on result:
positive indication of skin sensitisation
Remarks:
score + indicates the onset of a sensitising effect
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.01%
No. with + reactions:
16
Total no. in group:
16
Clinical observations:
contact reactivity with score ++
Remarks on result:
positive indication of skin sensitisation
Remarks:
score ++ shows a moderate sensitising response
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.1%
No. with + reactions:
16
Total no. in group:
16
Clinical observations:
contact reactivity with score +++
Remarks on result:
positive indication of skin sensitisation
Remarks:
score +++ demonstrates a clear sensitising response
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
1 %
No. with + reactions:
16
Total no. in group:
16
Clinical observations:
contact reactivity with score +++
Remarks on result:
positive indication of skin sensitisation
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
solvent without test substance
No. with + reactions:
0
Total no. in group:
4
Clinical observations:
reponse - to +- (negative to slight erythema)
Remarks on result:
no indication of skin sensitisation
Remarks:
negative response on challenge
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0.1 %
No. with + reactions:
6
Total no. in group:
6
Clinical observations:
Score ++
Remarks on result:
positive indication of skin sensitisation
Remarks:
score ++ shows a moderate sensitising response

There was a dose-related increase in the intensity of the delayed contact reactivity. There was also cross-reactivity with MC and DMBA as challenging agent and BaP with previous inducer. The intensity of the response was dose-related but primarily expressed at the higher challenge doses, i.e. weaker than with BaP as challenger.

Interpretation of results:
Category 1 (skin sensitising) based on GHS criteria
Remarks:
dose related intensity of the response with regard to the test substance concentration during challenge
Endpoint:
skin sensitisation: in vivo (non-LLNA)
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH

- ANALOGUE APPROACH JUSTIFICATION
Explanation is provided in endpoint summary IUCLID 7.4. The precursor compound, Coal-tar pitch, high temp. [CAS no. 65996-93-2]., has to be classified as skin sensitser due to BaP, which is a marked skin sensitiser in animal testing. For precautionary reasons, the heat-treated follow-up product, CTPhtht, has been classified, too, even though the BaP content is below 0.1%, hence below the cut-off limit classification.
Reason / purpose for cross-reference:
read-across source
Principles of method if other than guideline:
Read-across to the preceding entry:
Source substance: benzo[a]pyrene (benzo[def]chrysene), generic (commercial product);
Reference: Old LJ et al. 1993; WHO 1998; ATSDR 1995
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.001 %
No. with + reactions:
16
Total no. in group:
16
Clinical observations:
contact reactivity with score +
Remarks on result:
positive indication of skin sensitisation
Remarks:
score + indicates the onset of a sensitising effect / test result is adopted for the target substance CTPht
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.01 %
No. with + reactions:
16
Total no. in group:
16
Clinical observations:
contact reactivity with score ++
Remarks on result:
positive indication of skin sensitisation
Remarks:
score ++ shows a moderate sensitising response / test result is adopted for the target substance CTPht
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
0.1 %
No. with + reactions:
16
Total no. in group:
16
Clinical observations:
contact reactivity with score +++
Remarks on result:
positive indication of skin sensitisation
Remarks:
score +++ demonstrates a clear sensitising response / test result is adopted for the target substance CTPht
Key result
Reading:
1st reading
Hours after challenge:
24
Group:
test chemical
Dose level:
1 %
No. with + reactions:
16
Total no. in group:
16
Clinical observations:
contact reactivity with score +++
Remarks on result:
positive indication of skin sensitisation
Remarks:
test result is adopted for the target substance CTPht
Reading:
1st reading
Hours after challenge:
24
Group:
positive control
Dose level:
0.1 %
No. with + reactions:
6
Total no. in group:
6
Clinical observations:
Score ++ (3-Methylcholanthrene)
Remarks on result:
positive indication of skin sensitisation
Remarks:
score ++ shows a moderate sensitising response
Reading:
1st reading
Hours after challenge:
24
Group:
negative control
Dose level:
solvent without test substance
No. with + reactions:
0
Total no. in group:
4
Clinical observations:
reponse - to +- (negative to slight erythema)
Remarks on result:
no indication of skin sensitisation
Endpoint conclusion
Endpoint conclusion:
adverse effect observed (sensitising)
Additional information:

No data on sensitising potential is available about Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht), itself.

Benzo[a]pyrene (BaP) is a constituent of CTPhtht. It is present at a typical concentration of ca. 0.04 % with a maximum concentration of 0.1 %. Sensitising properties of BaP have been investigated. Therefore, BaP is used as supporting substance to characterise the sensitising potential of CTPhtht.

BaP has been proven to be strongly sensitising in a delayed hypersensitivity/contact sensitisation test with guinea pigs according to Gell PG and Benacerraf B J. Exp. Med. 113, 571 (1961). Based on this result, BaP is classified as Skin Sens. 1. Generic concentration limit of a skin-sensitising component in a mixture that triggers classification of that mixture also as skin-sensitising is 1% for skin sensitisers Cat. 1. Concentration of BaP in CTPhtht is ≤ 0.1 %. Therefore, it is not required to be classified as skin-sensitising.

However, other closely structure-related pitches (e.g. pitch, petroleum. arom., CAS No. 68187-58-6) were demonstrated to be sensitising Cat. 1A in a murine LLNA. This result will be taken into account in the assessment of a possible sensitising potential of CTPhtht. As related substances with a low content of BaP similar to that of CTPhtht have been proven to show a sensitising potential, CTPhtht is also considered skin-sensitising for precautionary reasons.


Respiratory sensitisation

Endpoint conclusion
Endpoint conclusion:
no study available

Justification for classification or non-classification

Skin Sensitisation

No data on the sensitisation potency of Pitch, coal tar, high-temp., < 1% 4- to 5-membered condensed ring aromatic hydrocarbons [EC no. 701-305-8] (CTPhtht), is available. Based on its benzo[a]pyrene (BaP) content (0.1 %), classification is not required. But other related pitches with similar low BaP concentrations (below 1 %) have experimentally been demonstrated to be strong skin sensitisers. Therefore, CTPhtht is self-classified by the registrant as skin sensitising Cat. 1 for precautionary reasons.

Respiratory Sensitisation

No experimental data on respiratory sensitisation available. However, based on long-term occupational experience, no classification required.