2,3-dichlorophenoxyacetic acid

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: The study had been performed in accordance with OECD Guideline No.: 423.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2006

Report date:

2006

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2,3-dichlorophenoxyacetic acid

EC Number:

221-022-9

EC Name:

2,3-dichlorophenoxyacetic acid

Cas Number:

2976-74-1

Molecular formula:

C8H6Cl2O3

IUPAC Name:

(2,3-dichlorophenoxy)acetic acid

Test material form:

solid: crystalline

Details on test material:

- Name of test material (as cited in study report): Dichlorophenoxyacetic acid
- Physical state: light beige powder
- Purity test date: 26. 09. 2005
- Lot/batch No.: 10
- Expiration date of the lot/batch: : 07. 2006
- Storage condition of test material: at room temperature, protected from light

Test animals

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: TOXI COOP KKT. Budapest, HUNGARY
- Age at study initiation: 40-45 days
- Weight at study initiation: 131.8-150.5 g
- Fasting period before study: approx. 20 hours (after the test item administration food was withheld for 3 hours)
- Housing: 3 animals / cage, in Techniplast 1291 type plastic cages. (425x266x180 mm)
- Diet (e.g. ad libitum): ad libitum, ssniff SM r/M-z+H complete feed for rats and mice supplied by TOXI COOP KKT.
- Water (e.g. ad libitum): potable water, ad libitum, offered daily in 500-ml drinking bottles sterilized before use (121 °C, 20 minutes)
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20.3-22.6 °C
- Humidity (%): 36-53 %
- Air changes (per hr): 10-15 / h
- Photoperiod (hrs dark / hrs light): 12 h dark / 12 h artificial light

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 1% methyl-cellulose

Details on oral exposure:

MAXIMUM DOSE VOLUME APPLIED: 2000 mg / kg bodyweight = 20 ml / kg test item in vehicle suspension

Doses:

2000 mg / kg

No. of animals per sex per dose:

6

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: for 6 hours after treatment and then at least twice a day
- Necropsy of survivors performed: yes ( gross)
- Other examinations performed: clinical signs of toxicity, status of skin, fur, eyes, mucous membranes, respiratory, circulatory, autonomic and central nervous system, somatomotor activity, body weight

Results and discussion

Effect levels

Sex:

female

Dose descriptor:

approximate LD50

Effect level:

> 2 000 mg/kg bw

Mortality:

One animal given 2000 mg/kg test item died (No.: 30) on the dosing day, probably in the evening hours. No lethalities occurred in the other five animals dosed with 2000 mg/kg on the dosing day or during the 14-day observation period.

Clinical signs:

Before death, moderate somnolence was observed in the animal, which died on the dosing day.
Except for sporadic moderate somnolence and a few cases of piloerection, recorded until Day 4 of the observation period, no other changes were observed in the appearance and behaviour of animals, which survived till the end of the 14-day observation period.

Body weight:

The mean bodyweights of surviving animals decreased on the first week of observation period, but increased continuously from Day 8 till the end of observation period.
The mean body weight gain of survivors was slightly lower than that of untreated female rats of the same age and strain at the comparison of days 1-8, but the weight gain of animals became similar to that of the historical controls thereafter (comparison of days 8-14 and 1-14, respectively).

Gross pathology:

The following necropsy finding were found in the died animal: red coloured urine on the fur in the hypogastric region, congested and thickened wall of urinary bladder, enlarged spleen, dark colour and gaseous content in small intestines, disseminated haemorrhages in thymus, dark-red areas in lungs. Tissues were selected for microscopic examination from this animal. Microscopic changes were found in the heart (multifocal myocyte degeneration and inflammation), kidneys (degeneration of proximal tubular epithelial cells, haemoglibin/myoglobin nephrosis), liver (erythrocyte phagocytosis, proliferated sinusoidal cells), thymus (multifocal haemorrhage and lymphocyte necrosis) and stomach (erosion). The cause of death was attributed to red blood cell lysis and myocyte damage.
No test item-related pathological macroscopic finding could be detected in survivors at terminal sacrifice.

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Under the applied test conditions, the aproximate calculated cut-off LD50 value of dichlorophenoxyacetic acid administered by oral route to Crl:(WI)BR rats was above 2000 mg/kg, therefore, according to the requirements of the Minister of Health 44/2000. (XII.27.) EüM regulation the test item could not be classified.