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Description of key information

A limit dose acute oral toxicity study in the rat is available for this substance

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records
acute toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
May 10, 2016 to September 02, 2016
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
according to
OECD Guideline 425 (Acute Oral Toxicity: Up-and-Down Procedure)
GLP compliance:
yes (incl. certificate)
Test type:
up-and-down procedure
Limit test:
Details on test animals and environmental conditions:
- Source: Animal Breeding Facility, Jai Research Foundation
- Females (if applicable) nulliparous and non-pregnant: Yes
- Age at study initiation: 10 to 12 weeks
- Weight at study initiation: Minimum: 186.3g, Maximum: 199.8g
- Fasting period before study: Overnight prior to dosing and 3 hours post dosing
- Housing: Rats were housed individually in standard polypropylene solid bottom cages which conform to the size recommendations in the most recent Guide for the Care and Use of Laboratory Animals (Natl. Res. Council, 2011). These cages have stainless steel top grills with steam sterilized corn cob bedding material and facilities for pelleted feed and drinking water (polypropylene bottle fitted with sipper tube). Rack units were rotated once in a week. Rats were provided with a wooden block in each cage.
- Diet (e.g. ad libitum): ad libitum; Teklad Certified Global High fiber rat pellet feed manufactured by Envigo, USA
- Water (e.g. ad libitum):ad libitum - polypropylene water bottle with a stainless steel nozzle
- Acclimation period: 8-20days
- Identification: Each rat was uniquely numbered on the tail using a tattoo machine. Appropriate labels were attached to the cages indicating the study number, test item code and sex, dose, study code, cage number and animal number.

- Temperature (°C): 20-23
- Humidity (%): 49-66
- Air changes (per hr): 17
- Photoperiod (hrs dark / hrs light): 12 (06:00 - 18:00)

IN-LIFE DATES: From: To: 25/05/2016 - 06/6/2016
Route of administration:
oral: gavage
corn oil
Details on oral exposure:
- Concentration in vehicle: 200 mg/ml
- Amount of vehicle (if gavage): Not indicated
- Justification for choice of vehicle: test material insoluble in aqueous vehicles, and formed an acceptable suspension in corn oil
- Lot/batch no. (if required): Sigma life science; Batch Nº MKBS6944V


2000 mg/kg bw
No. of animals per sex per dose:
5 females
Control animals:
Details on study design:
Study Design:
This study was conducted as a limit study with the dose level of 2000 mg/kg body weight. The first rat was given a single dose of 2000 mg 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone/kg body weight. No mortality was observed at this dose level up to 48 h post dosing. Therefore, rat N° 2, 3, 4 and 5 were treated with the same dose level of 2000 mg 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone/kg body weight, one at a time, separated by minimum 48 h intervals. As no mortality was observed at the dose level of 2000 mg 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone/kg body weight, the end point was achieved and further testing was not required.
The rats were observed for signs of toxicity and mortality at 0.5, 1, 2, 3, 4 and 5-6 hours post-administration on the day of dosing. Subsequently, the rats were observed twice a day for morbidity and mortality for a period of 14 days following oral dosing. The clinical signs were recorded once a day. Individual body weight was recorded prior to dosing on day 1, and on days 8 and 15.
At study termination, all the rats were humanely euthanised by carbon dioxide asphyxiation. All rats on the study were subject to a gross pathological examination consisting of an external examination and opening of abdominal and thoracic cavities. The stomach of each rat was opened, the contents rinsed/removed, and the mucosal surface was examined for signs of irritation, erosions, ulcers or any other findings. Gross macroscopic changes, if any, were recorded.

The LD50 was calculated using the Dixon’s maximum likelihood method using software (AOT 425 StatPgm)
Key result
Dose descriptor:
Effect level:
> 2 000 mg/kg bw
Based on:
test mat.
No mortality was observed in the study
Clinical signs:
No clinical signs were observed during the study
Body weight:
A normal (based on Lab Historical Data) increase in bodyweight was observed in all animals throughout the study.
Gross pathology:
External examination of the terminally sacrificed rats did not reveal any pathological lesions in any of the treated animals.
Internal: Visceral examination of the terminally sacrificed rats did not reveal any pathological lesions in any of the treated animals.
Interpretation of results:
GHS criteria not met
THe LD50 of 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone/kg body weight in female Wistar rats was determined to be >2000 mg/kg bw.
Executive summary:

An acute oral toxicity study(Up-and-Down Procedure) was conducted using five female Wistar rats given a single oral dose of1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolonemixed in corn oil. A Limit Test was conducted with 2000 mg/kg body weight. The first rat survived; hence the four additional female Wistar rats each received a single dose of 2000 mg/kg body weight according to the Up-and-Down Procedure. 

No sign of toxicity was observed in the rats treated with the1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazoloneat 2000 mg/Kg body weight.

All rats were active and healthy during the study. All the rats gained body weight by the end of the study. 

External and visceral examination of terminally sacrificed animals did not reveal any pathological lesions in any of the treated animals.

The acute oral LD50of the 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone was found to be greater than 2000 mg/kg body weight in female Wistar rats.

Endpoint conclusion
Endpoint conclusion:
no adverse effect observed
Quality of whole database:

Acute toxicity: via inhalation route

Endpoint conclusion
Endpoint conclusion:
no study available

Acute toxicity: via dermal route

Endpoint conclusion
Endpoint conclusion:
no study available

Additional information

The acute oral toxicity of 1-Phenyl-3-methyl-4-(p-dodecylphenylazo)-5-pyrazolone was determined to be >2000 mg/kg bw in female Wistar rats.

Justification for classification or non-classification

The LD50 is >2000 mg/kg bw, therefore the CLP and GHS criteria for classification for acute toxicity are not met.