2,4(1H,3H)-Pyrimidinedione, 1-(3,5-di-O-acetyl-2-deoxy-.beta.-L-erythro-pentofuranosyl)-5-methyl-

Endpoint summary

Description of key information

LDT600 C3 appeared to be a weak sensitizer with no irritating potential in the murine LLNA TIER I.

According the criteria described in CLP Directive EEC 1272/2008 the tested material has to be classified as a skin sensitizer Cat. 1 (H317).

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:

27.4. - 14.5.2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

Balb/c

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Charles River, Germany
- Age at study initiation: approximately 8 weeks
- Weight at study initiation: 17 - 20 g
- Housing: Animals were housed in groups of 3 in Macrolon cages (MIII type) with sterilized saw dust as bedding material and paper as cage enrichment.
- Diet: SSNIFF SM R/M-Z pelleted rodent diet, ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 d

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.2 - 23.4
- Humidity (%): 41 - 61
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES:
From: 27.4.2009
To: 14.5.2009

Vehicle:

dimethylformamide

Concentration:

50%, 5%, 0.5% (w/w)

No. of animals per dose:

6

Details on study design:

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
The dorsal surface of both ears was epidermally treated (25 μl/ear) with the test substance concentration, approximately the same time each day, for three consecutive days. The concentrations were mixed thoroughly using a vortex mixer immediately prior to dosing. The control animals were treated in the same way as the test substance groups, except that, instead of the test substance, the vehicle or positive control substance was administered.
Approximately 24 h after the last treatment, all animals were sacrificed by intraperitoneal injection with pentobarbital. Both ears (left and right) were punched in the apical area using a biopsy punch. For each animal both punches were immediately weighed pooled per animal using an analytical balance after which the punches were discarded.
Both auricular draining lymph nodes (left and right) of mice were excised. The relative sizes of the nodes (as compared to normal) were estimated by visual examination and abnormalities of the nodes and surrounding area were recorded. For each animal both lymph nodes were pooled and immediately weight using an analytical balance.
Following excision and weighing of the nodes, single cell suspensions of lymph node cells (LNC) were prepared in phosphate buffered saline (PBS) by gentle separation through stainless steel gauze. LNC were collected in approximately 0.7 mL of PBS in a 24 wells plate that was kept on ice as much as possible.
Cell counts were determined using a Coulter Counter Z1 Dual.

Positive control substance(s):

other: 0.5% 1-Chloro-2,4-Dinitrobenzene (DNCB)

Positive control results:

The positive control item DNCB elicited a reaction pattern with increased LN hyperplasia, which was in congruence with the expected mode of action of a contact allergen.

Key result

Parameter:

other: Ear weight index

Value:

1

Test group / Remarks:

Dimethyl formamide

Key result

Parameter:

other: Ear weight index

Value:

1.02

Test group / Remarks:

0.5% DNCB

Key result

Parameter:

other: Ear weight index

Value:

1

Test group / Remarks:

0.5% of the test substance LDT600 C3

Key result

Parameter:

other: Ear weight index

Value:

0.92

Test group / Remarks:

5% of the test substance LDT600 C3

Key result

Parameter:

other: Ear weight index

Value:

1

Test group / Remarks:

50% of the test substance LDT600 C3

Key result

Parameter:

other: LN weight index

Value:

1

Test group / Remarks:

Dimethyl formamide

Key result

Parameter:

other: LN weight index

Value:

2

Test group / Remarks:

0.5% DNCB

Key result

Parameter:

other: LN weight index

Value:

1.07

Test group / Remarks:

0.5% of the test substance LDT600 C3

Key result

Parameter:

other: LN weight index

Value:

0.95

Test group / Remarks:

5% of the test substance LDT600 C3

Key result

Parameter:

other: LN weight index

Value:

1.18

Test group / Remarks:

50% of the test substance LDT600 C3

Key result

Parameter:

SI

Remarks on result:

not measured/tested

The test doesn`t include a determination of DPM, but analysis of ear weight, increasing of LN cell counts, increase in LN cell weight and body weight. A substance is considered as a sensitizer, if an increasing of LN cell counts as well as LN cell weight can be observed.

No visual irritation of the ears was noted for the vehicle control group and groups treated with the test substance. The animals of the positive control group showed slight erythema. Visual examination of the nodes revealed that the majority of nodes were considered normal in size, except for the nodes of one animal at 0.5% and two animals at 5%, which were considered reduced in size. All nodes of the positive control animals were considered enlarged when compared to the vehicle control group. No macroscopic abnormalities of the surrounding areas were noted in any of the animals.

Body weights and body weight gain of experimental animals remained in the same range as controls over the study period and no clinical signs were observed.

The positive control item DNCB elicited a reaction pattern with increased LN hyperplasia, which was in congruence with the expected mode of action of a contact allergen.

The tested material did not cause any change in ear weight when compared to the vehicle control. The tested material did cause a dose related increase in LN cell counts when compared to the vehicle control. The tested material did not cause a dose related increase in LN weights when compared to the vehicle control.

In conclusion, the tested material appeared to be a weak sensitizer with no irritating potential in the murine LLNA TIER I.

Interpretation of results:

sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

LDT600 C3 appeared to be a weak sensitizer with no irritating potential in the murine LLNA TIER I.
According the criteria described in CLP Directive EEC 1272/2008 the tested material has to be classified as a skin sensitizer Cat. 1 (H317).

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available