Benzene, 1-chloro-4-isocyanato-2-(trifluoromethyl)-

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:

other information

Study period:

2003

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

- modification: in addition, measurements of ear swelling and ear weight were done to discriminate the irritating potential from the sensitizing potential of the test substance (Integrated Model for the Differentiation of Skin reactions (IMDS))

Principles of method if other than guideline:

Modified LLNA (IMDS; Integrated Model for the Differentiation of Skin Reactions). Modifications are authorised in the OECD TG 429 and in the Note for 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

Type of study:

mouse local lymph node assay (LLNA)

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 (SPF)
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: at least 7 days

Vehicle:

methyl ethyl ketone

Concentration:

0, 3, 10, 30 %
The test item was formulated immediately before each administration in MEK. The substance had been melted by using a watertank (60°C, approx. 1h) before formulation. The formulations were visually described as solutions. Stability of the test item in the vehicle was analytically verified for up to 2 hours.

No. of animals per dose:

6

Details on study design:

TREATMENT PREPARATION AND ADMINISTRATION:
The test item in the formulation or the vehicle were 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 used concentrations were based on the experiences with the test system and the toxic properties of the test substance.
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 physiological saline (PBS).
Investigations:
- weight of draining lymph nodes (given as weight index compared to vehicle controls)
- cell counts in draining lymph nodes (given as cell count index compared to vehicle controls)
Stimulation indices were calculated by dividing the absolute weight or number of cell counts of the substance treated lymph nodes by the vehicle treated ones.
- ear swelling (given in 0.01 mm and as index)
- ear weight (given in mg/8 mm diameter punch and as index)

Positive control substance(s):

other: The LLNA technology was checked using Alpha Hexyl Cinnamic Aldehyde formulated in different vehicles. The sensitivity as well as the reliability of the technique is thus confirmed by this study.

Statistics:

When it was statistically reasonable, the values from treated groups were compared with those from the control group by the Mann-Whitney or the Wilcoxon signigicance test (U-test) at significance levels of 5 and 1% (one-tailed for LLNA/IMDS or PNLA (larger)). Outlying values in the LN/ear weights or LN cell counts were eliminated at a probability level of 99% by Nalimov's method. In addition, for the LLNA/IMDS the smallest significant differentes in the means were calculated by Scheffels method, which according to Sachs can be used for both equal and unequal sample sizes.

Parameter:

SI

Remarks on result:

other: see Remark

Remarks:

All dosed groups (3%, 10% and 30%) of the NMRI mice showed a clear increase in the weights of the draining lymph nodes and clear increases in the stimulation indices for cell counts compared to control animals after application of the test item 4-Chloro-3-(trifluormethyl)-phenylisocyanat. The "positive level" which is 1.35 for cell count indices has been exceeded in all dose groups. These increases are of statistical significance. The increase of cell counts and lymph nodes weights was not always dose dependent. The "positive level" of ear swelling which is 0.01 mm increase [8,9], i.e. about 10% of the control values, has been exceeded or reached in the mid and the highest dose group. In all dose groups there was a statistically significant increase of the ear swelling compared to control animals. A statistically significant increase of the ear weights was detected in the mid and the highest dose group.

Table 1: Summary of the LLNA/IMDS results (means of 6 animals per group)

Parameter investigated	Vehicle control#	Dose  3%	Dose 10 %	Dose  30%
Stimulation index: weight of draining lymph nodes	1.00	3.18*	3.40*	3.69*
Stimulation index: cell count in draining lymph nodes	1.00	3.29*	3.25*	3.33*
Ear swelling in 0.01 mm on day 4 (index)	17.67 (1.00)	18.83* (1.07)	20.08* (1.14)	22.75* (1.29)
Ear weight in mg / 8 mm diameter punch on day 4 (index)	12.42 (1.00)	12.36 (1.00)	13.40* (1.08)	15.65* (1.26)

# DMSO

* statistically significant increase (p <= 0.05)

An increase in the stimulation indices for the weight or cell counts in the lymph nodes as well as for ear swelling or ear weights was seen and statistical analysis revealed significant effects for the test item.

Interpretation of results:

sensitising

Remarks:

Migrated information

Executive summary:

The test item was investigated in the modified Local Lymph Node Assay (LLNA-IMDS) on female mice according to OECD TG 429. Concentrations of 0 (vehicle control), 3, 10 and 30 % test item formulated in MEK were tested. The results show that the test item exerts a sensitizing potential in mice after dermal application at all tested concentrations. A significant difference compared to vehicle treated animals regarding the weight or cell counts of the draining lymph nodes as well as ear swelling was reached. The results show that the test item has a skin sensitizing potential in mice after demal application.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

The test item was investigated in the modified Local Lymph Node Assay (LLNA-IMDS) on female mice according to OECD TG 429. Concentrations of 0 (vehicle control), 3, 10 and 30 % test item formulated in MEK were tested. The results show that the test item exerts a sensitizing potential in mice after dermal application at all tested concentrations. A significant difference compared to vehicle treated animals regarding the weight or cell counts of the draining lymph nodes as well as ear swelling was reached. The results show that the test item has a skin sensitizing potential in mice after demal application.

Migrated from Short description of key information:
LLNA: the test item was shown to be a skin sensitizer

Justification for selection of skin sensitisation endpoint:
only one study available

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information:

No data are available to assess the potential for respiratory sensitization or asthma in humans. The chemical structure as aromatic monoisocyanate do not point per se to a respiratory sensitization activity.

Migrated from Short description of key information:
no data are available that point to a respiratory sensitization potential

Justification for classification or non-classification

According to EU-Directive 67/548/EEC 4-Chloro-3-(trifluormethyl)-phenylisocyanat shall be classified as skin sensitiser with R43. The Directive requires classification as respiratory sensitizer with R42 for all isocyanates.

According to Regulation (EC) No 286/2011 of 10 March 2011 amending Regulation (EC) No.1272/2008 4 -Chloro-3 -(trifluormethyl)-phenylisocyanat shall be classified as skin sensitizer Category 1. The data are not sufficient for sub-categorization.

The chemical structure as aromatic monoisocyanate does not per se point to a potential activity as respiratory sensitizer and no data are available for this endpoint. Thus, the substance will not be classified with regard to respiratory sensitization according to Regulation (EC) No 1272/2008.