[2-(2-methoxymethylethoxy)methylethoxy]propanol

Endpoint summary

Key value for chemical safety assessment

Skin sensitisation

Link to relevant study records

Reference

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-study according to OECD guideline 429.

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)

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: ca. 22-24 g
- 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

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22
- Humidity (%): 40-70
- Air changes (per hr): 12-15
- Photoperiod (hrs dark / hrs light): 12/12

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:

Screening Study: Three daily topical applications of 1%, 5%, 25%, 50%, 75%, or 100% TPGME 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 TPGME in the LLNA.

LLNA: Six female mice/group received 5%, 25%, or 100% TPGME, 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. TPGME at doses of 5%, 25%, and 100% elicited proliferative responses with stimulation indices (SI) that were respectively 1.3, 0.5, and 0.7, respectively, in comparison to vehicle-treated mice. TPGME 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.

Concentrations tested for the irritancy screen were selected based upon maximum miscibility in an appropriate LLNA vehicle while maintaining a solution suitable for application. Toxicity data regarding irritation potential were also taken into consideration. Concentrations tested in the LLNA were based on this information and previous dermal sensitization data. TPGME was combined with vehicle (4:1 AOO) to obtain concentrations of 5%, 25%, and 100%. Solutions were prepared daily just prior to dosing.
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 TPGME (1%, 5%, 25%, 50%, 75% or 100%), on the dorsal surface of each ear (25 µl) on three consecutive days. 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. Irritation to the mouse ears is only relevant in the context of the LLNA and should not be interpreted as an indication of irritation potential in humans.

LLNA: 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 TPGME (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 phosphatebuffered 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 one mouse was prepared by gentle mechanical disaggregation using a tissue homogenizer (Stomacher 80 Lab System, Seward Ltd., London, United Kingdom). The cells were washed two times and were suspended in 3 ml of 5% trichloroacetic acid (TCA) for approximately 18-70 hours. The suspended precipitates were centrifuged (200 x g for 10 minutes) and the supernatant removed. The pellet from each mouse was reconstituted in 1 ml of 5% TCA and subsequently transferred to a scintillation vial containing 10 ml of Aquasol-2 scintillation cocktail (Packard Instrument Company, Meridan, Connecticut). Two additional 2 ml aliquots of water were used to rinse the tubes and the rinses were added to the scintillation vials containing the 1 ml of pellet in TCA and cocktail. The radioactivity in each precipitate was measured using a beta-scintillation counter and reported as disintegrations per minute (dpm) per mouse. A mean dpm value + SD (standard deviation) was calculated for each experimental group.

Positive control substance(s):

hexyl cinnamic aldehyde (CAS No 101-86-0)

Statistics:

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 (Kimber et al., 1994). While the criterion for a positive response (SI > 3) was originally developed empirically, a recent robust statistical evaluation indicated that it is an acceptable practical value for hazard identification (Basketter et al., 1999a). Furthermore, by determining EC3 values (estimated concentration resulting in a 3-fold SI), one can compare relative sensitization potency of chemicals and/or formulations (Basketter et al., 1999b). While a test material that produces a SI of > 3 in the LLNA should be considered “positive” for contact sensitization (Kimber et al., 1994), recent opinions have suggested circumstances in which the LLNA result and sensitization potential should be further considered in the context of additional scientific judgment (Ryan et al., 2000; Basketter et al., 1998; Basketter et al., 2006). The EC3 value is determined by interpolating between two values one above and one below the SI value of 3 (Statistics and Calculations).

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

TPGME at doses of 5%, 25%, and 100% elicited proliferative responses with stimulation indices (SI) that were respectively 1.3, 0.5, and 0.7, respectively, in comparison to vehicle-treated mice. TPGME 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 proliferation when compared to vehicle-treated mice. 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.

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: See attached table for DPM data.

Interpretation of results:

not sensitising

Remarks:

Migrated information

Conclusions:

Tripropylene glycol methyl ether (TPGME) did not elicit a stimulation index (SI) that met the 3X threshold, 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 tripropylene glycol methyl ether (TPGME) 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% TPGME 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 TPGME in the LLNA. LLNA: Six female mice/group received 5%, 25%, or 100% TPGME, or vehicle (4:1 AOO) or 30% α-hexylcinnamaldehyde (HCA; positive control) on days 1-3. On day 6, uptake of 3Hthymidine 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. TPGME at doses of 5%, 25%, and 100% elicited proliferative responses with stimulation indices (SI) that were respectively 1.3, 0.5, and 0.7, respectively, in comparison to vehicle-treated mice. TPGME 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.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

TPGME at doses of 5%, 25%, and 100% elicited proliferative responses with stimulation indices (SI) that were respectively 1.3, 0.5, and 0.7, respectively, in comparison to vehicle-treated mice. TPGME 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.

Migrated from Short description of key information:
A GLP-study according to OECD guideline 429 is available for tripropylene glycol methyl ether.

Justification for selection of skin sensitisation endpoint:
The study was conducted according to OECD TG 429 and in accordance with the Principles of GLP.

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

Based on the absence of skin sensitising potential, genotoxicity and irritancy, tripropylene glycol methyl ether is not expected to be a respiratory tract sensitizer.

Migrated from Short description of key information:
No studies on respiratory sensitization are available for tripropylene glycol methyl ether but an assessment of sensitising potential was made using the skin sensitization and genotoxicity data.

Justification for classification or non-classification

Tripropylene glycol methyl ether 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. Hence, no classification for skin and respiratory sensitizer is required.