Methyl pyruvate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Data source

Reference

Reference Type:

publication

Title:

Utility of historical vehicle-control data in the interpretation of the local lymph node assay

Author:

D. A. BASKETTER, N. J. GILMOUR, D. BRIGGS, L.G. ULLMANN, G. F. GERBERICK, C. A. RYAN, R. J. DEARMAN, I. KIMBER

Year:

2003

Bibliographic source:

Contact Dermatitis 2003: 49: 37–41

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay)

Version / remarks:

OECD, 2002

Deviations:

yes

Remarks:

detailed documentation missing

GLP compliance:

no

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

1

Reference substance name:

Methyl pyruvate

EC Number:

209-987-4

EC Name:

Methyl pyruvate

Cas Number:

600-22-6

Molecular formula:

C4H6O3

IUPAC Name:

methyl 2-oxopropanoate

Details on test material:

Obtained from Sigma (Poole, Dorset, UK).
No further data given.

Specific details on test material used for the study:

3-Methyl pyruvate (99%)

In vivo test system

Test animals

Species:

mouse

Strain:

other: CBA/Ca

Sex:

not specified

Details on test animals and environmental conditions:

- Age at study initiation: 7–12 weeks
No further details given.

Study design: in vivo (LLNA)

Vehicle:

acetone/olive oil (4:1 v/v)

Concentration:

1%, 2.5%, 5%, 10%

No. of animals per dose:

4

Details on study design:

Animales were treated topically on the dorsum of both ears with 25µl of test material or with an equal volume of the vehicle (AOO) alone. Treatment was performed daily for 3 consecutive days. 5 days following the initiation of exposure, all mice were injected via the tail vein with 250 µl of phosphate-buffered saline (PBS) containing 20 µCi of tritiated thymidine. Mice were sacrificed 5 h later, and the draining lymph nodes excised and pooled for each experimental group.
Single cell suspension of LNCs was prepared by mechanical disaggregation. The LNC suspension was washed 2 times in an excess of PBS and then precipitated with 5% trichloroacetic acid at 4 celsius for 18 h. Pellets were resuspended in TCA, and the incorporation of tritiated thymidine measured by ß-scintillation counting.

Positive control substance(s):

not specified

Statistics:

The EC3 value was calculated by interpolating between 2 points on the SI axis, one immediately above and one immediately below the SI value of 3. The vehicle-treated control value (by definition, SI=1) cannot be used for the latter. Where the data points lying immediately above and below the SI value of 3 have the co-ordinates (a, b) and (c, d), respectively, then the EC3 value was calculated using the equation:
EC3 = C + [3 - d/b - d] (a - c)

Results and discussion

In vivo (LLNA)

Results

Parameter:

EC3

Value:

2.4

Cellular proliferation data / Observations:

Test 1: dpm/node
AOO control 134
1% 791
2.5% 1541
5% 2618
10% 4565

Clear dose–response relationship, but in the context of an unusually low concurrent vehicle-control value of 134 disintegrations per minute (dpm)/node. This value was substantially below the mean control value obtained by this laboratory (2.5th percentile of respective historical control data is 187 dpm/node).

Test 2: dpm/node (repeated test)
AOO control 477
1% 576
2.5% 1531
5% 2232
10% 3791

EC3 = 2.4%

Applicant's summary and conclusion

Conclusions:

The test substance 3-Methyl pyruvate has been found to be a skin sensitizer in the LLNA under the chosen testing conditions. The present data on dermal sensitization fulfill the criteria laid down in EU) 1272/2008, and therefore, a classification with "Skin sensitisation" (Category 1B) is warranted.