7-hydroxy-3-(4-methoxyphenyl)-4-benzopyrone

Endpoint summary

Description of key information

A GLP in vivo skin sensitisation study was performed in accordance with OECD Guideline 429. 25 µL of test material was applied to the dorsum of each ear of female mice, once daily for three days. Formononetin produced a stimulation index of <3 in all groups of test animals and is therefore not considered a sensitiser.

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

Study period:

6 February - 3 June 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.2600 (Skin Sensitisation)

Deviations:

no

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Type of study:

mouse local lymph node assay (LLNA)

Specific details on test material used for the study:

- Lot No. of test material: 07-170-FIL-2/3
- Appearance: White powder
- Expiration date: May 2010
- Purity: 98.4%
- Storage condition of test material: Room temperature

Species:

mouse

Strain:

CBA:J

Sex:

female

Details on test animals and environmental conditions:

TEST ANIMALS
- Source: Harlan Sprague-Dawley, Indianapolis, IN
- Females nulliparous and non-pregnant: yes
- Age at study initiation: Approx. 9 weeks old
- Weight at initial dose day: 19.4 - 23.9 g
- Housing: Suspended, wire bottom, stainless steel cage; 1 animal per cage
- Diet: PMI Feeds Inc. Formulab #5008; available ad libitum
- Water: Municipal water supply available ad libitum from automatic water system
- Acclimation period: At least 5 days
- Indication of any skin lesions: Not specified

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 3°C
- Humidity (%): 30 - 70%
- Air changes (per hr): 10 - 12 air changes/ hour
- Photoperiod (hrs dark / hrs light): 12 hour light/dark cycle

IN-LIFE DATES: 12 March 2008 To: 20 March 2008

Vehicle:

propylene glycol

Concentration:

25 µL of an appropriate dilution (25% or 50%) of the test substance or 100% test substance moistened with propylene glycol

No. of animals per dose:

5 animals per dose

Details on study design:

MAIN STUDY

TREATMENT PREPARATION AND ADMINISTRATION:
The test substance was applied to the dorsum of both ears. The vehicle control group (5 females) was treated in the same way as the test animals but with vehicle alone (propylene glycol) instead of test substance. The positive control group (5 females) was treated with 90% alpha-hexylcinnamaldehyde in acetone: olive oil. The animals were treated once daily for 3 days.
All test and control animals were given a 2-day rest period on Days 4 and 5.
On Day 6 of the study, all test and control animals were injected in the tail vein with 250 µL of 0.01 M phosphate-buffered saline, pH 7.4 containing 20 µCi of [methyl,1,2-3H] Thymidine. Five hours after the injection, the animals were sacrificed, the draining auricular lymph nodes were excised and pairs from each individual animal were processed.
Incorporation of tritiated thymidine was measured by liquid scintillation counting as disintegrations per minute (DPM) from the paired lymph nodes of each animal and mean DPM/ animal was calculated for each group.

BODY WEIGHTS AND OBSERVATIONS:
Individual body weights were recorded on Day 1 prior to dosing and Day 6 prior to injection. All test and control animals were observed daily for clinical signs of toxicity and any signs of excessive irritation at the test site.

Positive control substance(s):

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

Positive control results:

The positive control test substance produced a stimulation index of ≥3 and is therefore considered a sensitiser.

Key result

Parameter:

SI

Value:

0.8

Test group / Remarks:

Test Group I - 25% test substance concentration

Key result

Parameter:

SI

Value:

1.4

Test group / Remarks:

Test Group II - 50% test substance concentration

Key result

Parameter:

SI

Value:

0.7

Test group / Remarks:

Test Group III - 100% test substance concentration

Cellular proliferation data / Observations:

STIMULATION INDEX
See Table 1

CLINICAL OBSERVATIONS:
All animals appeared normal for the duration of the study.

BODY WEIGHTS:
One Test Group 1 animal lost weight during the study.

Table 1: Stimulation Index (SI) or Test/Vehicle Control Ratio for each test group

Animal group	Test substance concentration	Average count per mouse (DPM)	Number of mice in group	Test/vehicle control ratio (SI)
Vehicle control	NA	379	5	NA
Test Group I	25%	307	5	0.8
Test Group II	50%	514	5	1.4
Test Group III	100%	275	5	0.7
Positive control	NA	8082	5	21.3*

NA – not applicable

* - positive control used to confirm animal sensitisation potential and validate procedures

ENVIRONMENT:

- Actual temperature: 20 - 21°C

- Actual relative humidity: 44 - 95% (Humidity was outside of the protocol range but did not affect the study outcome)

Interpretation of results:

GHS criteria not met

Conclusions:

Formononetin produced a stimulation index of <3 in all groups of test animals and is therefore not considered a sensitiser.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Respiratory sensitisation

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

In a LLNA study performed according to OECD Guideline 429 the test substance produced a Stimulation Index of < 3 in all groups of test animals. Therefore, Formononetin is not considered to be a sensitiser and does not require classification.