Trichloroethylene

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:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD guideline study, conducted under GLP.

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Species:

mouse

Strain:

other: CBA/J strain, inbred, SPF quality

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Female mice, CBA/J strain, inbred were supplied by Harlan, Horst, The Netherlands
- Age at study initiation: approx. 10 weeks old
- Weight at study initiation: 22-24 grams
- Housing: individual housing in labeled Macrolon cages (MI type; height 12.5 cm) containing sterilized sawdust as bedding material.
- Diet (e.g. ad libitum): free access to pelleted rodent diet
- Water (e.g. ad libitum): Free access to tap water
- Acclimation period: at least 5 days before the start of the treatment, under laboratory conditons.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21.0 ± 3.0ºC (actual range: 19.7 - 23.1ºC),
- Humidity (%): 40-70% (actual range: 31.4 - 65%)
- Air changes (per hr): approximately 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours artificial fluorescent light and 12 hours darkness per day.

IN-LIFE DATES: From: day 1 To: Day 6

Vehicle:

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

Concentration:

In the main study, three experimental groups of five female CBA/J mice were treated with test substance concentrations of 5, 25 or 100% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with vehicle alone (Acetone/Olive oil (4:1 v/v)).

No. of animals per dose:

Groups of five mice were treated.

Details on study design:

RANGE FINDING TESTS:
Two test substance concentrations were tested; a 50% and 100% concentration. The highest concentration was the maximum concentration as required in the test guidelines (undiluted for liquids). The test system, procedures and techniques were identical to those used during Days 1 to 3 of the main study. Two young adult animals were selected (8-14 weeks old). Each animal was treated with one concentration on three consecutive days. Approximately 3-4 hours after the last exposure, the irritation of the ears was assessed. Body weights were determined on Day 3. The animals were sacrificed after the final observation and no necropsy was performed.

MAIN STUDY
ANIMAL ASSIGNMENT AND TREATMENT
- Name of test method: Local Lymph Node Assay in the mouse.
- Criteria used to consider a positive response: Disintegrations Per Minute (DPM) values are presented for each animal and for each dose group. A Stimulation Index (SI) is calculated for each group. The SI is the ratio of the DPM/group compared to DPM/vehicle control group. If the results indicate a SI ≥ 3, the test substance may be regarded as a skin sensitizer, based on the test guideline and recommendations done by ICCVAM. The results were evaluated according to the Globally Harmonized System of Classification

TREATMENT PREPARATION AND ADMINISTRATION:
Induction - Days 1, 2 and 3
The highest test substance concentration (100%) used in the main study was selected from the preliminary irritation study. Three experimental groups of five female CBA/J mice were treated with test substance concentrations of 5, 25 or 100% w/w on three consecutive days. The dorsal surface of both ears was epidermally treated (25 μL/ear) with the test substance concentration, at approximately the same time per day. The concentrations were mixed thoroughly using a vortex mixer immediately prior to dosing. The control animals were treated the same as the experimental animals, except that, instead of the test substance, the vehicle alone was administered.

Excision of the nodes - Day 6
Three days after the last exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes wereexcised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of Disintegrations Per Minute (DPM) and a stimulation index (SI) was subsequently calculated for each group.

Positive control substance(s):

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

Positive control results:

A reliability check is carried out at regular intervals to check the sensitivity of the test system and the reliability of the experimental techniques as used by NOTOX. In this study, performed in September/October 2009, females of the CBA/J mouse strain (Charles River France, L’Arbresle Cedex, France) were checked for sensitivity to Alpha- Hexylcinnamaldehyde, technical grade. The females were approx. 11 weeks old at commencement of the study. The study was based on the OECD Guideline No. 429, EC No 440/2008, Part B.42 and EPA, OPPTS 870.2600 “Skin Sensitization”. Alpha-hexylcinnamicaldehyde, technical grade (CAS no. 101-86-0) was fabricated under lot no. 13102MO (Sigma- Aldrich, Steinheim, Germany) and the 3H-methyl
thymidine was purchased from PerkinElmer Life Sciences, Boston, MA, USA. HCA concentrations used for this study were 5, 10 and 25% in Acetone/Olive oil (4:1 (v/v)).

The SI values calculated for the substance concentrations 5, 10 and 25% were 1.4, 1.2 and 5.1 respectively. An EC3 value of 16.9% was calculated using linear interpolation. The calculated EC3 value was found to be in the acceptable range of 2 and 20%. The results of the 6 monthly HCA reliability checks of the recent years were 13.1, 15.6, 14.1, 13.8, 13.9, 16.0 and 11.9%. Based on the results, it was concluded that the Local Lymph Node Assay as performed at NOTOX is an appropriate model for testing for contact hypersensitivity.

Parameter:

SI

Remarks on result:

other: See attached PDF with tables 3, 4 and figure 1 from the original report.

Parameter:

other: disintegrations per minute (DPM)

Remarks on result:

other: See attached PDF with tables 3, 4 and figure 1 from the original report.

See attached PDF with tables 3, 4 and figure 1 from the original report.

Interpretation of results:

sensitising

Remarks:

Migrated information

Conclusions:

The SI values calculated for the substance concentrations 5, 25 and 100% were 1.2, 3.6 and 14.1 respectively. These results indicate that the test substance could elicit an SI ≥ 3. An EC3 value (the estimated test substance concentration that will give a SI =3) of 20.0% was calculated. Based on these results and according to the recommendations made in the test guidelines, trichloroethylene would be regarded as skin sensitiser.

According to the Regulation (EC) No 1272/2008 on classification, labeling and packaging of substances and mixtures, tetrachloroethylene should be classified as skin sensitizer (Category 1) and labeled as H317: May cause an allergic skin reaction. Based on the EC3 value of 66%, tetrachloroethylene can be categorized as weak sensitizer based on the proposal of ECETOC (European Centre for Ecotoxicology and Toxicology of Chemicals). Contact Sensitisation: Classification According to Potency. Technical Report No. 87. Brussels, April 2003 (ISSN-0773-8072-87).

Executive summary:

The study was carried out according to OECD guideline No. 429. Test substance concentrations selected for the main study were based on the results of a preliminary study. In the main study, three groups of five female CBA/J mice were treated with test substance concentrations of 5, 25 or 100% w/w on three consecutive days, by open application on the ears. Five vehicle control animals were similarly treated, but with vehicle alone (Acetone/Olive oil (4:1 v/v)). Three days after the last exposure, all animals were injected with 3H-methyl thymidine and after five hours the draining (auricular) lymph nodes were excised and pooled for each animal. After precipitating the DNA of the lymph node cells, radioactivity measurements were performed. The activity was expressed as the number of Disintegrations Per Minute (DPM) and a stimulation index (SI) was subsequently calculated for each group. The slight irritation of the ears as shown by all animals treated at 100% and one animal treated at 25% was considered not to have a toxicologically significant effect on the activity of the nodes. The majority of auricular lymph nodes were considered normal in size, except for the nodes in the animals of the highest dose groups. Mean DPM/animal values for the experimental groups treated with test substance concentrations 5, 25 and 100% were 559, 1688 and 6640 DPM respectively. The mean DPM/animal value for the vehicle control group was 470 DPM. The SI values calculated for the substance concentrations 5, 25 and 100% were 1.2, 3.6 and 14.1 respectively. These results indicate that the test substance could elicit an SI ≥ 3. An EC3 value (the estimated test substance concentration that will give a SI =3) of 20.0% was calculated. The six monthly reliability check with Hexylcinnamaldehyde indicates that the Local Lymph Node Assay as performed is an appropriate model for testing for contact hypersensitivity.

Based on these results, trichloroethylene would be regarded as skin sensitiser.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (sensitising)

Additional information:

Based on a LLNA and a GPMT with positive results, trichloroethylene has to be classified as a skin sensitiser.

Trichloroethylene is a widely used substance to which many people have had repeated dermal exposure. There have been very few reports of apparent skin sensitisation.There have been a few cases of individuals exposed to trichloroethylene apparently developing skin sensitisation to the substance, but the sparsity of such cases and the extensive use of trichloroethylene suggest that skin sensitisation is a highly idiosyncratic reaction.

Migrated from Short description of key information:
Based on a LLNA and a GPMT with positive results, trichloroethylene has to be classified as a weak skin sensitiser.

Justification for selection of skin sensitisation endpoint:
Reliable study

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

There are no reports of respiratory sensitisation in humans. Given the large number of people that have been exposed to trichloroethylene by the inhalation route and considering the general toxicological characteristics of trichloroethylene, all the evidence indicates that this substance is not a respiratory sensitiser.

Migrated from Short description of key information:
There are no reports of respiratory sensitisation in humans. Given the large number of people that have been exposed to trichloroethylene by the inhalation route and considering the general toxicological characteristics of trichloroethylene, all the evidence indicates that this substance is not a respiratory sensitiser.

Justification for classification or non-classification

Based on a GPMT with positive results, trichloroethylene should be classified for skin sensitisation according to Directive 67/548/EEC (R43) and EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 (Skin sensitisation 1; H317).