Registration Dossier

Classification & Labelling & PBT assessment

PBT assessment

Currently viewing:

Administrative data

PBT assessment: overall result

Type of composition:
legal entity composition of the substance
State / form:
solid: particulate/powder
Reference substance:
Composition 1
PBT status:
the substance is not PBT / vPvB

Classification of 4-methyl-1-phenyl-3-pyrazolidone for effects in the environment:


The chemical 4-methyl-1-phenyl-3-pyrazolidone(CAS no. 2654-57-1) is used as intermediate for chemical synthesis and pharmaceutical industry. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for 4-methyl-1-phenyl-3-pyrazolidone. The PBT criterion was herein assessed based on experimental data in conjunction with standardized environmental fate models. Here follows a description of the PBT assessment.


Persistence assessment

The tested substance fulfils the P criterion within Annex XIII based on the assessment that here follows:


Biotic degradation

42-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test chemical (Experimental study report, 2017). The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Domestic waste water containing surface soil and soil samples was used as a test inoculum for this study. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/l. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using the values BOD & ThOD was determined to be 64.45%. Degradation of Sodium Benzoate exceeds 39.15% on 7 days & 52.4% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD42 value of test chemical was observed to be 0.21 mgO2/mg. ThOD was calculated as 1.99 mgO2/mg. Accordingly, the % degradation of the test chemical after 42 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 10.55%. Based on the results, the test chemical, under the test conditions, was considered to be not readily biodegradable in nature.


Thus, based on the available information, it indicates that chemical 4-methyl-1-phenyl-3-pyrazolidone can be considered to be not readily biodegradable in water and thus likely to be persistent (P) in nature.



Bioaccumulation assessment

The tested substance does not fulfil the B criterion within Annex XIII based on the assessment that here follows:


Theoctanol water partition coefficient of the test chemical was determined to be 0.6242 at 25°C, which is less than the threshold of 4.5. If this chemical is released into the aquatic environment, there should be a low risk for the chemical to bioaccumulate in fish and food chains.


Toxicity assessment

The tested substance fulfils the T criterion within Annex XIII based on the assessment that here follows:



The tested chemical is regarded to be not classified for carcinogenicity, mutagenicity and reprotoxicity, Further, there is no evidence of chronic toxicity, as identified by the classifications STOT (repeated exposure), category 1(oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume) or category 2 (oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume).


Aquatic organisms

All of the available short-term eco-toxicity data for fish, invertebrates and algae for the substance indicates the LC50/EC50 value to be in the range 0.625 to 10.58 mg/L, respectively. These value suggest that the substance is likely to be hazardous to Aquatic organisms at environmentally relevant concentrations and can be considered to be classified in ‘Aquatic Acute Category 1’ / ‘Aquatic Chronic Category 1’ as per the CLP regulation.


There are no available long-term toxicity evaluations for 4-methyl-1-phenyl-3-pyrazolidone. By speculation, long-term NOEC for aquatic organisms can be expected for the substance at concentration below 0.01 mg/L based on the data mentioned above


The chemical was therefore considered as hazardous to aquatic environments as per the criteria set out in Annex XIII.




Based on critical, independent and collective evaluation of information summarized herein, the tested compound fulfils the P and T criterion but does not fulfil the B criterion and has therefore not been classified as a PBT compound within Annex XIII.