2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

Skin sensitisation

Administrative data

Endpoint:

skin sensitisation: in vivo (non-LLNA)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07.08.2008 - 05.10.2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

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 406 (Skin Sensitisation)

GLP compliance:

yes (incl. QA statement)

Type of study:

guinea pig maximisation test

Justification for non-LLNA method:

Other in vivo data available. Study according to OECD 406 The Guinea pig maximization test (GPMT) was performed in the past for the purpose of other regulatory programs – crop protection regulations.

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

EC Number:

249-636-2

EC Name:

2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

Cas Number:

29450-45-1

Molecular formula:

C17H25ClO3

IUPAC Name:

2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

impurity 1

Reference substance name:

(4-chloro-2-methylphenoxy)acetic acid

EC Number:

202-360-6

EC Name:

(4-chloro-2-methylphenoxy)acetic acid

Cas Number:

94-74-6

Molecular formula:

C9H9ClO3

IUPAC Name:

(4-chloro-2-methylphenoxy)acetic acid

Test material form:

liquid

In vivo test system

Test animals

Species:

guinea pig

Strain:

Dunkin-Hartley

Sex:

male

Details on test animals and environmental conditions:

TEST ANIMALS AND HUSBANDRY
Species
Dunkin Hartley, Albino guinea pigs Hodowla zwierząt laboratoryjnych Ilkowice 41, 32-218 Slaboszow, Poland,
35 animals (Animal Delivery Protocol No. 20B/2008).
Starting Body Weight: 400-565 g.

Number and Sex:
20 males - treated group (Animals No. 1-20)
10 males - control group (Animals No. 21-30)
5 males - pilot study (Animals No. 31-35)

Housing and feeding:
Animals were housed in cages in groups of 5. The temperature of experimental animal room was 22±2°C with the relative humidity 40-70 %; lighting was artificial 12 h light/12hdark.
Conventional laboratory diet (TOP DOVO Dobra Voda, supplier) and drinking water with addition of ascorbic acid in concentration 0.05% were served ad libitum. The sanitation was made according to standard procedures.

Acclimation
19.8.2008 — 2.9.2008

Results and discussion

In vivo (non-LLNA)

Results

Results 1

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

test chemical

Dose level:

Topical Application: 10% MCPA 2-EH in Olive oil

No. with + reactions:

5

Total no. in group:

20

Clinical observations:

No changes in behaviour and health of animals were observed after application of MCPA-2 EH. Significant differences of the body weight between control and treated group were not registered on the start and on the end of the study.

Remarks on result:

other: 72 hours after start of challenge application, which gives 48 hours after removing of the patch

Results 2

Key result

Reading:

2nd reading

Hours after challenge:

72

Group:

negative control

Dose level:

no concetration of tested substance. Only vehicle used.

No. with + reactions:

0

Total no. in group:

10

Remarks on result:

other: 72 hours after start of challenge application, which gives 48 hours after removing of the patch

Results 3

Key result

Reading:

1st reading

Hours after challenge:

24

Group:

positive control

Dose level:

From 0.5 to 5.0% for intradermal injection. From 5.0 to 100.0 for topical application

No. with + reactions:

5

Total no. in group:

5

Remarks on result:

other:

Remarks:

Results from Pilot study

Applicant's summary and conclusion

Interpretation of results:

Category 1 (skin sensitising) based on GHS criteria

Executive summary:

RESULTS AND DISCUSSION

The test substance does not mix with water, therefore it could not use Physiological saline or Aqua pro injectione as vehicle, as was stated in Study plan. Test substance was mixable with olive oil, which it was used as vehicle article.

No changes in behaviour and health of animals were observed after application of MCPA-2EH. Significant differences of the body weight between control and treated group were not registered on the start and on the end of the study.

Score of reaction for MCPA-2EH

observation time / hours/	total number animals	number of positive tested animals	score of reaction					sensitisation rate (%)
			0	1	2	3	4
48	20	5	15	2	3	0	0	25
Sensitisation response		Mild sensitiser (grade H )

 

Re-challenge was not realized because the well-defined reactions were observed.

There were observed very slight and well-defined erythema 24 and 48 hours after removing of

the patch. The oedema hasn't been observed. The reactions of test animals which exceed the most severe control reaction are presumed to be due to sensitization.

The calculated sensitisation potential of MCPA-2 EH is 25%.

Conslusions:

Topical application of 10% MCPA-2EH in Olive oil induced the sensitization rate 25 %. According to this value the product MCPA-2EH belongs to the group of "mild sensitizer"(II).