3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate homopolymer, isocyanurate type

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2002-07-15 - 2003-03-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

- modified LLNA (IMDS): Measurement of cell counts instead of radioactive labeling. In addition, measurements of ear swelling and ear weights were done to discriminate the irritating potential from the sensitizing potential of the test substance.

Principles of method if other than guideline:

Modified LLNA (IMDS; Integrated Model for the Differentiation of Skin Reactions). Modifications are authorized in the OECD TG 429 and the Note of
Guidance SWP/ 2145/00 of the CPMP (2001). Information on validation of IMDS and scientific justification is given in: Vohr HW et al., Arch. Toxicol.,
73, 501-509 (2000); Ehling G et al., Toxicology 212, 60-68 and 69-79 (2005).

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:

3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, oligomers

EC Number:

500-125-5

EC Name:

3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, oligomers

Cas Number:

53880-05-0

Molecular formula:

residual C12H18N2O2, otherwise C36H54N6O6 (trimer) and higher species

IUPAC Name:

3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate homopolymer

Constituent 2

Reference substance name:

3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate homopolymer, isocyanurate type

EC Number:

931-312-3

Cas Number:

53880-05-0

Molecular formula:

residual C12H18N2O2, otherwise C36H54N6O6 (trimer) and higher species

IUPAC Name:

3-Isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate homopolymer, isocyanurate type

Details on test material:

Desmodur Z 4470 MPA/X; Batch No. 2.4/1-6; isophorone diisocyanate (IPDI) homopolymer of Bayer AG, purity not reported, 70 % solution in
1-Methoxypropylacetate-2/Xylol (1:1)

In vivo test system

Test animals

Species:

mouse

Strain:

NMRI

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan-Winkelmann GmbH, Borchen, Germany
- Strain: Hsd Win: NMRI
- Age at study initiation: no data
- Weight at study initiation: no data
- Housing: individual
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22+/- 2
- Humidity (%): 40 - 70
- Air changes (per hr): about 10
- Photoperiod (hrs dark/ hrs light): 12/12

Study design: in vivo (LLNA)

Vehicle:

dimethylformamide

Remarks:

The stability of the test item in the vehicle was analytically verified for up to 2 hours.

Concentration:

0, 3, 10, 30%

No. of animals per dose:

6

Details on study design:

TREATMENT PREPARATION AND ADMINISTRATION:
The test item was formulated immediately before each administration in dimethylformamide. The test item in the formulation was applied
epicutaneously onto the dorsal part of both ears of the animals. This treatment was repeated on three consecutive days (d0, d1 and d2). The volume
administered was 25µl/ear.
The animals were anaesthetized by inhalation of carbon dioxide and sacrificed one day after the last application (d3). The appropriate organs were
then removed. Lymphatic organs (the auricular lymph nodes) were transferred into physiiological saline (PBS).
Investigations:
- weight of lymph nodes
- cell counts in lymph nodes
- stimulation index is calculated by dividing the absolute number of weight or cell counts of the substance treated lymph nodes by the vehicle treated ones.
- ear swelling
- ear weight

Positive control substance(s):

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

Statistics:

When it was statistically reasonable, the values from treated groups were compared with those from the control group(s; vehicle) by a the Mann-
Whitney (Ann. Math. Stat. 18, 1947, 50-60) or the Wilcoxon (Biometrics 1, 1945, 80-83) significance test. at significance levels of 5%. Outlying values
in the LN weights were eliminated at a probability level of 99% by Nalimov's method (Statistik für naturwissenschaftliche Berufe, 1982, 88-89). In
addition, for the LLNA/IMDS the smallest significant differentes in the means were calculated by Scheffe's method (Biometrica 40, 1953, 87-104),
which according to Sachs (Angewandte Statistik 6th and 10th edition, Springer Verlag, Berlin, 1978/2002 ) can be used for both equal and unequal
sample sizes.

Results and discussion

Positive control results:

Performed in 2002. The "positive level" which is 1.3 for cell counts has been statistically significant exceeded in the highest dose group (30%).
(Cell index/concentration: 0.88 / 3%; 1.13/ 10%; 1.77/ 30%)

In vivo (LLNA)

Results

Results 1

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

The "positive level" which is 1.3 for cell counts has been exceeded in all dose groups, but the increase was only statistifically significant in the lowest dose group (3%). Cell count index = 2.29 (3%) / 1.43 (10%) / 1.68 (30%); test substance: 70 % solution in 1-Methoxypropylacetate-2/Xylol (1:1)

Results 2

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: modified LLNA; measurement of cell counts instead of radioactive labeling

Any other information on results incl. tables

Compared to vehicle-treated animals, there was no increase regarding weight of the draining lymph nodes in all dose groups (weight index = 1.16 (3%) / 1.14 (10%) / 1.26 (30%)). The "positive level" of ear swelling which is 2 x 10exp-2 mm increase has not been reached or exceeded in any dose group. A slight significant increase compared to vehicle treated animals regarding ear swelling was detected in the highest dose group. No increase in the ear weights were observed in any dose group. (ear swelling - day 0 = 18.67 (0%) / 18.00 (3%) / 18.75 (10%) / 18.17 (30%); - day 3 = 18.17 (0%) / 18.25 (3%) / 18.92 (10%) / 19.50 (30%); ear weight - day 3 = 11.53 (0%) / 11.33 (3%) / 11.58 (10%) / 11.68 (30%))

Applicant's summary and conclusion

Conclusions:

The results show that the test item (Desmodur Z 4470 MPA/X) has a slight irritating and a sensitizing potential in mice after dermal application.

Executive summary:

A modified LLNA (IMDS; OECD TG 429) was performed on 6 female NMRI mice per dose group using test item concentrations of 0% (vehicle control), 3%, 10% and 30%.

 

There was no increase compared to control animals regarding weight of the draining lymph nodes in all dose groups. Compared to vehicle treated animals the cell counts exceeded the "positive levels" defined for this assay in all dose groups, but only in the lowest group the increase was statistically significant. A slight significant increase compared to vehicle treated animals regarding ear swelling was detected in the highest dose group. No increase was determined for the ear weights in any dose group.

Under the conditions of this study the test item IPDI homopolymer has a slight irritating and a sensitizing potential in mice after dermal application.