Docosan-1-ol

Endpoint summary

Description of key information

The key skin sensitisation study is read-across from the structurally analogue substance icosan-1-ol (CAS 629 -96 -9; EC 211-119-4). The study, which was conducted according to OECD Test Guideline 406, and in compliance with GLP, reports the test material to be not sensitising to guinea pig skin (RTC, 2000).

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March, 15th - May, 12th 2000

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 406 (Skin Sensitisation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.6 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

An LLNA study was not performed because there is an existing reliable study for skin sensitisation using the Guinea Pig Maximisation test method. Furthermore, the LLNA test method is not considered to be suitable for fatty alcohols. Please refer to the attached document for further details.

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Nossan S.r.l., Correzzana (MI), Italy
- Age at study initiation: 5 -6 weeks
- Weight at study initiation: 672.9 ± 61.9 g (control), 629.9 ± 62.0 g (test group)
- Housing: stainless steel cages (48x63x41 cm) with a grid floor in groups of 5 animals
- Diet: commercially available laboratory diet (Altromin MSK) ad libitum
- Water: drinking water ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): 45 - 65
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 2000-03-15 To: 2000-05-12

Route:

intradermal and epicutaneous

Vehicle:

corn oil

Concentration / amount:

5% test substance in vehicle or Freund's complete adjuvant for intradermal induction
75% test substance in vehicle for topical induction
10% test substance in vehicle for challenge

No.:

#1

Route:

epicutaneous, occlusive

Vehicle:

corn oil

Concentration / amount:

5% test substance in vehicle or Freund's complete adjuvant for intradermal induction
75% test substance in vehicle for topical induction
10% test substance in vehicle for challenge

No. of animals per dose:

Range finding: 2 for injection tolerance test, 5 for topical tolerance test
Main test: 10 for test group, 5 for control group

Details on study design:

RANGE FINDING TESTS:
Intradermal injection tolerance test: 0.1 ml of the test item in concentrations of 10, 5, 1, 0.5, 0.1 and 0.05% in vehicle injected intradermally, evaluation after 6 days
Topical application tolerance test: with 0.1 ml of emusified Freund's complete adjuvant (FCA) intradermally injected animals (2 injections) were treated topically for 24 hrs (epicutaneous, occlusive, duplicate application) after 8 days with concentrations of 75, 50, 20, 10 and 5% test substance in vehicle, evaluation 24 and 48 hours after removal of dressings

MAIN STUDY
A. INDUCTION EXPOSURE
- No. of exposures: 2
- Exposure period:
Intradermal: single application, skin reactions assessed approx. 24 hrs after injection
Epicutaneous: 48 hrs, evaluation 24 hrs after patch removal
- Test groups:
Intradermal: 3 pairs of injections (0.1 ml each) at anterior, median and posterior positions; anterior: emulsified FCA, median: test substance in corn oil, posterior: test substance in emulsified FCA
Epicutaneous: 0.4 ml of test substance in corn oil (the day before 0.5 ml of sodium lauryl sulphate at 10% concentration was spread evenly over the skin surrounding the injections sites)
- Control group: Animals of the control group were treated in the same manner except that the test item was replaced by vehicle alone
- Site:
Intradermal: scapular region over an area approx. 20 x 40 mm, all injections were made at the edge of the prepared site and the anterior and median injections were positioned close together and distant from the posterior injections
Epicutaneous: gauze patches were covered with the test solutions (0.4 ml each) and placed over the injection sites, this was covered with strips of aluminium foils and the animals were then wrapped with lengths of elastic adhesive bandages
- Frequency of applications: Day1: intradermal injections, Day7: pretreatment with sodium lauryl sulphate, Day8: epicutaneous application
- Duration: 3 weeks
- Concentrations:
Intradermal: 5% in corn oil, 5% in emulsified FCA
Epicutaneous: 75% in corn oil

B. CHALLENGE EXPOSURE
- No. of exposures: 1
- Day(s) of challenge: Day 22
- Exposure period: 24 hrs
- Test groups: 0.2 ml aliquots of the test substance in corn oil on patches of gauze measuring 20x20 mm were applied on the right flank of each animal, the left flank of each animal was similarly treated with 0.2 ml of vehicle (petrolatum) alone
- Control group: same treatment as test substance animals
- Site: clipped flanks, area approx. 50x50 mm on each flank
- Concentrations: 10% in corn oil
- Evaluation: 48 and 72 hrs after challenge (24 and 48 hrs after removal of dressings)

Positive control substance(s):

yes

Remarks:

Mercaptobenzothiazole

Positive control results:

Most recent reliability check performed in September/October 1999.
Concentrations:
Induction: 1% positive control substance in PEG 400 (injection); 50% positive control substance in acetone (topical)
Challenge: 25% positive control substance in acetone

100% response in test group and 0% response in control group at challenge: test system regarded as valid.

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

test chemical

Dose level:

10%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

no indication of skin sensitisation

Key result

Reading:

1st reading

Hours after challenge:

48

Group:

negative control

Dose level:

10%

No. with + reactions:

0

Total no. in group:

5

Remarks on result:

no indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

10%

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

no indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

72

Group:

negative control

Dose level:

10%

No. with + reactions:

0

Total no. in group:

5

Remarks on result:

no indication of skin sensitisation

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

25% positive control substance in acetone

No. with + reactions:

5

Total no. in group:

5

Remarks on result:

positive indication of skin sensitisation

Reading:

2nd reading

Hours after challenge:

48

Group:

positive control

Dose level:

25% positive control substance in acetone

No. with + reactions:

5

Total no. in group:

5

Remarks on result:

positive indication of skin sensitisation

Interpretation of results:

GHS criteria not met

Conclusions:

The test item does not elicit a sensitisation response in the guinea pig, there being no reaction observed at challenge.

Executive summary:

The potential of the test item, NAFOL 2022, to induce and elicit delayed dermal sensitisation was assessed by a guinea pig model using the maximisation test of Magnusson and Kligman.

The concentrations of the test item used in the main study were determined by the results of preliminary screening tests. The main sensitisation test was undertaken using a test group of 10 animals and a control group of 5 animals. In an attempt to induce sensitisation, test animals were intradermally injected with an emulsion of Freund's complete adjuvant (FCA) and the test item at 5% concentration in both the selected vehicle and an emulsion of FCA. One week later this was boosted by topical application of the test item at 75% concentration over the injection sites. Control group animals were treated in the same manner but the selected vehicle (corn oil) was used in place of the test item. Two weeks after the second induction stage, all animals were challenged by topical application of both the vehicle (petrolatum) and the test item at 10% concentration.

At challenge no response to the test item was observed in any animal of the test or control groups following topical exposure to the test item at 10% concentration. No reaction to the vehicle alone was observed in any animal of test or control groups.

These results indicate that the test item, NAFOL 2022, does not elicit a sensitisation response in the guinea pig, there being no reaction observed at challenge.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

The key skin sensitisation study was the most recent study available with the structurally analogue substance icosan-1-ol (CAS 629 -96 -9; EC 211-119-4). It was conducted according to OECD Test Guideline 406, and in compliance with GLP. The study reports the test material to be not sensitising (RTC, 2000). At induction, 0.1 ml of 5 % of test material in corn oil and emulsified FCA was injected intradermally into 10 test guinea pigs. 7 Days later, 0.4 ml of 75 % of test material in corn oil was applied epicutaneously under occlusive dressing for 48 hours. The skin reaction was evaluated at 24 hours after the intradermal injection and topical induction. At challenge, 0.2 ml of 10 % of test material in corn oil was applied onto the test area for 24 hours under occlusive dressing. The skin reaction was evaluated at 24- and 48-hours post-application. No signs of erythema and oedema were observed at 24 and 48 hours after challenge. Appropriate negative and positive control groups were used and gave the expected results. The available supporting skin sensitisation studies confirm the findings of the key study.

Discussion of trends in the Category of C6-24 linear and essentially-linear aliphatic alcohols:

There is evidence throughout the carbon number range C6-C24 that long chain alcohols are not sensitising; this conclusion does not vary with carbon number within the Category: read-across substances are chosen based on carbon chain length and similarity of physicochemical properties.

A mouse local lymph node assays (LLNA) performed with Alcohols C14-15 branched and linear and with Alcohols C16-17 branched and linear was positive, although this study, which has significant deficiencies in terms of methodology and presentation of results, may have been confounded by skin irritation (House 2000). The LLNA studies pre-date the guideline, OECD TG 429, which indicates that for certain classes of substances, the LLNA may give false positives, and refers to Basketter et al (2009). This paper presents information on two fatty alcohols, and concludes that the fatty alcohols are not sensitisers, and may give a true false positive in the local lymph node assay. For such substances, use of the guinea pig maximisation assay is recommended. Data from guinea pig maximisation assays are available for a number of constituents of the substance and for multi-constituent substances with similar composition; the majority of these studies gave clear negative results. Therefore no classification is proposed for sensitisation, and the Category conclusion is that the members of the C6-24 alcohols category are not sensitisers.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the available data, docosan-1-ol does not require classification for skin sensitisation according to Regulation (EC) No 1272/2008.