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Administrative data

Endpoint:
skin sensitisation: in vivo (LLNA)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
01/2009-03/2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-study according to OECD guideline 429

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report date:
2009

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)
GLP compliance:
yes (incl. QA statement)
Type of study:
mouse local lymph node assay (LLNA)

Test material

Constituent 1
Chemical structure
Reference substance name:
1-propoxypropan-2-ol
EC Number:
216-372-4
EC Name:
1-propoxypropan-2-ol
Cas Number:
1569-01-3
Molecular formula:
C6H14O2
IUPAC Name:
1-propoxypropan-2-ol
Details on test material:
- Name of test material (as cited in study report): DOWANOL™ PNP Glycol Ether (1-Propoxy-2-propanol)
- Substance type: colorless liquid
- Lot/batch No.: Union Carbide Corporation, a wholly owned subsidiary of The Dow Chemical Company, Seadrift, Texas (lot # AA0155R504/233382).

In vivo test system

Test animals

Species:
mouse
Strain:
CBA
Sex:
female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan (Indianapolis, Indiana)
- Age at study initiation: 9-12 weeks
- Weight at study initiation: 24 g (mean)
- Housing: Animals were housed up to six per cage in filter tubs containing corncob bedding, food pellets and a water bottle. On the day the animals were euthanized and following the injection of 3H-thymidine, each treatment group of mice was housed in shoebox cages containing corncob bedding, food pellets, and a crock filled with water. The mice were euthanized five hours later.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least one week prior to the start of the study

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 1°C
- Humidity (%): 40-70%
- Air changes (per hr): 12-15 times/hour
- Photoperiod (hrs dark / hrs light): 12-hour light/dark (on at 6:00 a.m. and off at 6:00 p.m.)

Study design: in vivo (LLNA)

Vehicle:
acetone/olive oil (4:1 v/v)
Concentration:
Screening study: 1%, 5%, 25%, 50%, 75% and 100%
Final study: 5%, 25% and 100%
No. of animals per dose:
6
Details on study design:
Irritation screen:

Prior to the LLNA study, several concentrations of the test material were evaluated for irritation potential as measured by erythema of the ears. Mice (one female/concentration) received one application of PnP (1%, 5%, 25%, 50%, 75%, or 100%), on the dorsal surface of each ear (25 µl) on three consecutive days. The test solutions (25 µl/ear) were spread over the dorsal surface of each ear in a manner to prevent material loss. Ears were inspected prior to application of the test material solutions, and erythema was evaluated on days 2, 3, and 6. All mice were weighed on days 1 and 6. Erythema scores and body weight data following test material applications were compared to the response of the animals treated with vehicle alone.

Main study:

The application of the test material (25 μl/ear) was made on the dorsal surface of both ears as described above. Six female mice/group received one of three concentrations of PnP (5%, 25%, or 100%) or vehicle (4:1 AOO) once daily for three consecutive days. HCA at 30% (v/v) in vehicle was run concurrently as a positive dermal sensitization control. Ears were inspected prior to application of the test material solutions, and erythema was evaluated on days 2, 3, and 6. All mice were weighed on days 1 and 6. On day 6, all mice received a 250 μl intravenous injection (i.v.) via the lateral tail vein containing 20 μCi of 3H-thymidine (specific activity 2Ci/mmol; Amersham code TRA310, Buckinghamshire, United Kingdom) diluted in phosphate-buffered saline (PBS). Approximately five hours post administration, the mice were euthanized via CO2 asphyxiation and both auricular lymph nodes located at the bifurcation of the jugular veins were excised and placed in PBS. A single cell suspension of the auricular lymph nodes from each mouse was prepared and the cells were washed and suspended in 5% trichloroacetic acid (TCA) for approximately 18-70 hours. The suspended precipitates were centrifuged and the supernatant removed. The pellet from each mouse was reconstituted in 5% TCA and subsequently transferred to a scintillation vial containing Aquasol-2 scintillation cocktail. The radioactivity in each precipitate was measured using a beta-scintillation counter and reported as disintegrations per minute (dpm) per mouse.

Positive control substance(s):
hexyl cinnamic aldehyde (CAS No 101-86-0)
Statistics:
Mean dpm values + SD (standard deviation) were calculated for each experimental group. The SI was calculated using the absolute dpm value for each mouse as the numerator and the mean dpm value from the vehicle control mice as the denominator; the mean SI + SD was calculated for each experimental group. Any test material that produces a SI of > 3 in the LLNA should be considered “positive” for contact sensitization.

Results and discussion

Positive control results:
Proper conduct of the LLNA was demonstrated via the positive response from the positive control, 30% HCA which elicited a stimulation index (SI) that was 6.4 in comparison to vehicle-treated mice.

In vivo (LLNA)

Resultsopen allclose all
Parameter:
SI
Remarks on result:
other: see Remark
Remarks:
Mice dosed with 5%, 25%, and 100% PnP elicited proliferative responses with stimulation indices (SI) that were respectively 1.6, 1.2, and 1.1 in comparison to vehicle-treated mice. PnP did not demonstrate dermal sensitization potential in the mouse LLNA as the lymph nodes draining the area of topical application did not demonstrate a 3-fold increase in proliferation when compared to vehicle-treated mice.
Parameter:
other: disintegrations per minute (DPM)
Remarks on result:
other: see attachment below

Applicant's summary and conclusion

Interpretation of results:
not sensitising
Remarks:
Migrated information
Conclusions:
PnP did not elicit a stimulation index (SI) that met the 3-fold increase, thus indicating a lack of dermal sensitization potential in the mouse LLNA.
Executive summary:

The Local Lymph Node Assay (LLNA) was conducted to assess the potential of PnP to cause contact sensitization by measuring lymphocyte proliferative responses from auricular lymph nodes following topical application of the test material to the mouse ear. Screening Study: Three daily topical applications of 1%, 5%, 25%, 50%, 75% or 100% PnP were given to one animal at each dose level. Erythema was absent and body weights were unaffected in all dose groups. Results from this study were used to determine the dosing concentrations for PnP in the LLNA. LLNA: Six female mice/group received 5%, 25%, or 100% of PnP, or vehicle (4:1 AOO) or 30% α-hexylcinnamaldehyde (HCA; positive control) on days 1-3. On day 6, uptake of 3H-thymidine into the auricular lymph nodes draining the site of chemical application was measured five hours post administration. Proper conduct of the LLNA was confirmed via a positive response using 30% α-hexylcinnamaldehyde (HCA), a moderate contact sensitizer, which elicited proliferation that was 6.4 in comparison to vehicle-treated mice. Erythema was absent and body weights were unaffected in all dose groups Mice dosed with 5%, 25%, and 100% PnP elicited proliferative responses with stimulation indices (SI) that were 1.6, 1.2, and 1.1, respectively, in comparison to vehicle-treated mice. PnP did not demonstrate dermal sensitization potential in the mouse LLNA as the lymph nodes draining the area of topical application did not demonstrate a 3-fold increase in proliferation when compared to vehicle-treated mice.

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