Urea, reaction products with formaldehyde

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008-09-17 - 2008-10-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The GLP study was conducted according to an internationally accepted guideline. All study parameters are based on the specific guideline.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of study:

mouse local lymph node assay (LLNA)

Test material

Test material information

Constituent 1

Reference substance name:

Urea, reaction products with formaldehyde

EC Number:

271-898-1

EC Name:

Urea, reaction products with formaldehyde

Cas Number:

68611-64-3

Molecular formula:

not available

IUPAC Name:

Urea, reaction products with formaldehyde

Test material form:

other: liquid

In vivo test system

Test animals

Species:

mouse

Strain:

Balb/c

Sex:

female

Study design: in vivo (LLNA)

Vehicle:

other: DAE 433 - mixture of 40% dimethylacetamide, 30% acetone and 30% ethanol

Concentration:

The test substance was administered in the form of suspension in D AE 433.

Concentration in formulation: 30% (w/v).......................300 mg/mL

3% (w/v)...........................30 mg/mL

0.3% (w/v)..........................3 mg/mL

The highest concentration 30% (w/v) was determined from the pilot experiment and consecutive concentrations were selected according to Ulrich (2007).

No. of animals per dose:

Exposed groups - 18 females (6 animals in three groups)
Positive control group - 6 females
Negative control group - 6 females
Reserve group - 4 females

(reserve animals were intended for possible replacement of the animals in other groups during the acclimatisation period)
Total: 37 animals

Positive control substance(s):

other: Dinitrochlorbenzene (DNCB)

Results and discussion

Any other information on results incl. tables

Group	LN weight		LN cell count		Ear weight
	Mean (mg)	Index	Mean (10^6/mL)	Index	Mean (mg)	Index
NC	3.40	1.00	4.77	1.00	21.38	1.00
PC	9.32*	2.74+	18.32*	3.84+	25.02*	1.17+
0.3%	3.43	1.01	5.28	1.11	21.78	1.02
3%	3.87	1.14	3.63	0.76	21.03	0.98
30%	3.88	1.14	5.67	1.19	21.92	1.02

Figures with asterisk = values statistically significant on probability level 0.05 (Mann- Whitney test) Figures with cross = values exceeding thresholds NC - Negative control group PC - Positive control group

Applicant's summary and conclusion

Interpretation of results:

not sensitising

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

The test substance. Weikoform (Urea, reaction product with formaldehyde), elicited negative result in LLNA test.

Executive summary:

The test substance, Weikoform (Urea, reaction product with formaldehyde), was tested for the assessment of skin sensitisation potential with the murine local lymph node assay. This study is a part of the test substance health hazard evaluation. The Local Lymph Node Assay (LLNA) was used. This method was performed with endpoint different from that described in original guideline (non radioactive measuring of cell proliferation). This testing was conducted according to EU method B.42 with modifications as described in publications of Ulrich P, Streich J, Suter W, 2001; Ehling et al„ 2005; Ehling et al„ 2005A. In this study the contact allergenic potential of Weikoform (Urea, reaction product with formaldehyde) was evaluated after topical application to female BALB/c mice. Six mice per group were exposed by test and control substances on the dorsum of both ears once a day during 3 consecutive days. Draining lymph nodes were taken off at 24 hours after the last application. Concentrations: positive control DNCB (dinitrochlorobenzene): 0.5% (w/v) and Weikoform (Urea, reaction product with formaldehyde): 30%, 3%, 0.3% (w/v). Endpoints: ear weight, auricular (ear-draining) lymph node weights and cell counts = lymph node (LN) hyperplasia. The animals exposed to the test substance at the highest concentration showed skin reactions (hyperaemia and oedema) and slight negative clinical symptoms of intoxication (excitation, clonospasm and decreased reaction) throughout the experiment. There were no clinical observations attributable to the treatment with test substance at the middle and lower dose level. There was no difference in body weight increment of all groups in comparison to the vehicle control. The positive control substance DNCB elicited a reaction pattern with statistically significant increase in ear weight and LN hyperplasia, which was in congruence with his expected mode of action as a contact allergen. The test substance Weikoform (Urea, reaction product with formaldehyde) did not show a tendency to increase ear weight in anyone of dose levels tested. These results confirmed existing dermal irritation data (acute dermal irritation study was performed in CETA with negative results - Expert Report No. 08105, VUOS-CETA, 2008). Comparison of values between treated groups and control group revealed that the test substance Weikoform (Urea, reaction product with formaldehyde) did not cause statistically significant increase in LN cell count or in LN weight. Also index of LN weight and LN cell count was not exceeded in any dose level. In conclusion, at the given experimental conditions the test substance, Weikoform (Urea, reaction product with formaldehyde), elicited negative result in LLNA test.