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Skin sensitisation

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Administrative data

skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report Date:

Materials and methods

Test guideline
according to
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
not specified
GLP compliance:
yes (incl. certificate)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Details on test material:
As per IUCLID5 Sections 1.1. - 1.4.

In vivo test system

Test animals

Details on test animals and environmental conditions:
Female CBA/Ca mice were obtained from Harlan UK Ltd. All animals were in the weight range 17.0 to 23.8 g and approximately eight to twelve weeks of age prior to dosing on Day 1. The mice were acclimatised to the experimental environment for at least 5 days prior to the start of the study. Mice were housed individually in polycarbonate cages with woodflake bedding. The temperature and relative humidity controls of the animal room were set to maintain the range of 19 to 23°C and 40 to 70% respectively. Artificial lighting was controlled to give a cycle of 12 hours continuous light and 12 hours continuous dark per 24 hr. The animals were allowed free access to a standard rodent diet (Rat and Mouse No. 1
Maintenance Diet). Potable water taken from the public supply was freely available via polycarbonate bottles fitted with sipper tubes.

Study design: in vivo (LLNA)

acetone/olive oil (4:1 v/v)
50% v/v high dose level.
No. of animals per dose:
Details on study design:
The concentrations of Crude 1,3-dichloropropene used for the study were, 10, 25 and 50% v/v. Groups of four mice were treated at one of three concentrations of the test substance. The mice were treated by daily application of 25 μl of the appropriate concentration of the test
substance to the dorsal surface of each ear for three consecutive days (Days 1-3). The test substance was applied to the dorsal surface of each ear using an automatic micropipette. The test substance was spread over the entire dorsal surface of the ear using the tip of the pipette.
A further group of four mice received the vehicle alone in the same manner. During induction all animals were observed daily for signs of ill health or toxicity. The ears were also examined for signs of irritation.

Five days following the first topical application of Crude 1,3-dichloropropene (Day 6) all mice were injected via the tail vein with 250 μl of phosphate buffered saline containing 3H-methyl Thymidinea (3HTdR: 80 μCi/mL) giving a nominal 20 μCi to each mouse. The injection into the tail vein was carried out using a plastic syringe and needle after the mouse had been heated in a warming chamber. Five hours following the administration of 3HTdR on Day 6 all mice were humanely sacrificed by carbon dioxide asphyxiation and the draining auricular lymph nodes excised and pooled for each experimental group. 1.0 mL of phosphate buffered saline was added to the pooled lymph nodes for each group. A single cell suspension of lymph node cells was prepared by gentle mechanical disaggregation through a stainless steel gauze (200 mesh size). The pooled cell samples were then washed by adding 10 mL phosphate buffered saline, pelleted at 190 x g for 10 minutes and resuspended. The cells were washed twice again and resuspended in 3 mL trichloroacetic acid (TCA: 5%) following the final wash. After overnight incubation with 5% TCA at 4°C, the precipitate was recovered by centrifugation and resuspended in 1 mL 5% TCA and transferred to 10 mL Ultima Gold scintillation fluid on Day 7. 3HTdR incorporation was measured by β-scintillation counting. The proliferative response of lymph node cell suspension was expressed as radioactive disintegrations per minute per lymph node (dpm/node) and as the ratio of 3HTdR incorporation into cells of test nodes relative to that recorded for control nodes (test/control ratio).
Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
No data

Results and discussion

Positive control results:
Positive control substance hexyl cinnamic aldehyde (HCA) at a concentration of 25% v/v produced a Stimulation Index of 6.

In vivo (LLNA)

Resultsopen allclose all
Key result
Test group / Remarks:
Key result
Test group / Remarks:
Key result
Test group / Remarks:

Any other information on results incl. tables

There were no deaths and no signs of ill health, irritation or toxicity observed during this study. The Effective concentration 3 (EC3) was calculated and determined to be 34% v/v.

Applicant's summary and conclusion

Interpretation of results:
Migrated information
Based on a Stimulation Index of 5.5 at the high concentration of Crude 1,3-dichloropropene of 50% v/v, Crude 1,3-dichloropropene is considered to be a skin sensitizer in this assay. However, the limitations of the LLNA only allow prediction of the induction phase.

Following E.C.H.A. "Guidance on information requirements and chemical safety assessment, Chapter R. 8: Characterisation of dose [concentration]-response for human health", Section R. Table R. 8-3, page 30, page 36, Appendix R.8-10, Skin Sensitization, page, 128 and Appendix R. 8-3, Table R.8-19, page 76, the Dermal DNEL for Crude 1,3-dichloropropene was derived. The reported EC3 value for 1,3-dichloropropene in the LLNA was 34%. The mouse scaling factor is 7, the LOAEL to NOAEL Assessment Factor is 3 and the Intraspecies Assessment Factor worker is 3 (General Population is 5). The Total Assessment Factor worker is 63 and the Dermal DNEL (worker) = 135 ug/cm2. The Dermal DNEL (General Population) = 81 ug/cm2.
Executive summary:

Crude 1,3 -dichloropropene was assessed for the potential to induce skin sensitization in the mouse by an O.E.C.D. Guideline for Testing of Chemicals No. 429 “Skin Sensitization: Local Lymph Node Assay” with GLP compliance. Based on a Stimulation Index of 5.5 at the high concentration of Crude 1,3-dichloropropene of 50% v/v, Crude 1,3-dichloropropene is considered to be a skin sensitizer in this assay. However, the limitations of the LLNA only allow prediction of the induction phase.