Octyl (R)-2-(4-chloro-2-methylphenoxy)propionate

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 423 (Acute Oral toxicity - Acute Toxic Class Method)

Version / remarks:

(2001)

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Test material

Test material information

Constituent 1

Reference substance name:

Octyl (R)-2-(4-chloro-2-methylphenoxy)propionate

EC Number:

266-358-7

EC Name:

Octyl (R)-2-(4-chloro-2-methylphenoxy)propionate

Cas Number:

66423-13-0

Molecular formula:

C18H27ClO3

IUPAC Name:

octyl (2R)-2-(4-chloro-2-methylphenoxy)propanoate

Constituent 2

Reference substance name:

Mecoprop-P n-octyl ester

IUPAC Name:

Mecoprop-P n-octyl ester

Constituent 3

Reference substance name:

Preventol B5

IUPAC Name:

Preventol B5

Constituent 4

Reference substance name:

R-(+)-2-(4-chloro-2-methylphenoxy)-propionicacid, octyl ester

IUPAC Name:

R-(+)-2-(4-chloro-2-methylphenoxy)-propionicacid, octyl ester

Details on test material:

- Stability under test conditions: The analytical data verify that the test item in the vehicle used for testing is stable at room temperature for at least 2 hours

Test animals

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Strain: HsdCpb:Wu
- Source: Harlan GmbH, 5960 AD Horst, Netherlands
- Age at study initiation: approximately 8-12 weeks
- Weight at study initiation: 161-198 g
- Fasting period before study: Food was withheld from the animals for approximately 16-24 h before administration of the test item, and they were fed again approximately 2-4 h after administration.
- Housing: The animals were group caged conventionally in polycarbonate cages on low dust wood granulate bedding.
- Diet and water: ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2
- Humidity (%): 55 +/- 5
- Air changes (per hr): approx. 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

Administration volume: 10 mL/kg bw

Doses:

2000 mg/kg bw , 300 mg/kg bw

No. of animals per sex per dose:

6 (3 animals per step)

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Clinical signs and mortality rates were determined several times on the day of administration and subsequently at least once daily. The weight gain was checked weekly until the end of the study.
- Necropsy of survivors performed: yes

Statistics:

The LD50 value was estimated according to OECD TG 423, Annex 2d (2001).

Results and discussion

Effect levels

Sex:

female

Dose descriptor:

LD50

Effect level:

500 mg/kg bw

Remarks on result:

other: LD50 cut off according OECD TG 423, Annex 2d

Mortality:

3 deaths at 2000 mg/kg, no deaths at 300 mg/kg (1st and 2nd step)

Clinical signs:

other: The following clinical signs were observed in animals dosed with 2000 mg/kg bw: poor reflexes, decreased reactivity, lateral position and laboured breathing. In animals dosed with 300 mg/kg bw no clinical signs were observed.

Gross pathology:

In animals treated with 2000 mg/kg bw that died during the observation period a black, spotted liver was detected. The necropsies performed at the end of the study revealed no particular findings in animals treated with 300 mg/kg bw.

Applicant's summary and conclusion

Executive summary:

An acute oral toxicity study according to OECD TG 423 (Acute Toxic Class Method) was conducted with a starting dose of 2000 mg/kg test item formulated in corn oil. As 100% mortality occurred for this dose the next lower dose (300 mg/kg) was employed. No mortalities occurred for this dose neither in the 1st nor in the 2nd step. Thus, according to OECD TG 423, Annex 2d, the LD50 cut off is 500 mg/kg for Mecoprop-P n-octyl ester.

For the rats of dose group 2000 mg/kg poor reflexes, decreased reactivity, lateral position and laboured breathing were observed. At necropsy a black spotted liver was detected for the same dose level. For the 300 mg/kg dose level no clinical signs, effects on body weight gain or gross pathology findings were reported.