4-(1-methyl-1-phenylethyl)-N-[4-(1-methyl-1-phenylethyl)phenyl]aniline

Endpoint summary

Description of key information

The substance is non-toxic to aquatic organisms at the limit of solubiltity in water, and is not persistent.  Classification is not applicable.

Additional information

The test substance is a solid under all environmental conditions and is of low solubility in water (<0.0067 mg/l) and is of low volatility (based on0.667 kPa at 20 °C).  The substance was determined to have a log Koc value of 6.54, indicating a high affinity for soil/sediment. As such, any environmental release will result in virtually all of the substance compartmentalising into soil/sediment compartments, with little release directly to atmosphere or compartmentalising to water compartments. 

 

Any potential exposure to the environment is predicted to result in redistribution to both water and soil; however due to its low volatility, low water solubility and partitioning values, these indicate that the majority of the substance would eventually partition to soil rather than the water compartment should it be released to the environment.  

 

A Level III fugacity model was conducted in the US EPA EPISUITE (Mackay,) which assumes steady-state but not equilibrium conditions. The Level III model in EPI Suite predicts partitioning between air, soil, sediment and water using a combination of default parameters and various input parameters. This model has been used to calculate the theoretical distribution of a range of components present in the substance between four environmental compartments (air, water, soil, sediment) at steady state in a unit world. The results obtained from modelling are as follows: 

 

Air (%)	Water (%)	Soil (%)	Sediment (%)
0.036	2.07	2.86	95

 

 It is proposed that the majority of the substance is modelled to distribute to the sediment compartments within the constraints of the QSAR model. As such, and given the low solubility, the soil and sediment compartments are proposed to the areas to which partitioning would occur. 

 

The substance displays a low ready biodegradability in that it achieved 29% biodegradation in a 28-day CO2 evolution ready biodegradation study, and 5% in at wo-phase closed bottle test.   Further assessments where conducted in soil and sediment with the following results:

 Results from simulation testing on degradation in soil;

In accordance with ECHA Decision number: CCH-D-2114494377-34-01/F, the following studies were conducted for environmental fate:

• Soil simulation testing (Annex IX, Section 9.2.1.3.; test method: Aerobic and anaerobic transformation in soil, EU C.23./OECD TG 307) at a temperature of 12 °C with the registered substance;

The results of this study are as follows:

The output values for the chosen model for each test system are presented in the table below.

Soil type	Model	r^2	χ^2(%)	DT90 at 12°C (days)	DT50 at 12°C (days)
Soil I	SFO	0.9288	13	88.4	26.6
Soil II	SFO	0.8996	8.12	263	79.3
Soil III	HS	0.9583	4.98	498	102
Soil IV	HS	0.9886	3.45	158	88.4

[¹⁴C]4-(1-methyl-1-phenylethyl)-N-[4-(1-methyl-1-phenylethyl)phenyl]aniline disappeared over time in all soils, with DT_{50 ­}values of 26.6, 79.3, 102 and 88.4 days in Soils I, II, III and IV respectively.

Almost no mineralisation occurred, with < 2% measured in all soils over 120 days.

10%, 12%, 14% and 4% of applied radioactivity remained in the soil residue for Soils I, II, III and IV respectively at Day 120 after all extractions had been carried out.  ‘Harsh’ ASE extractions removed less than 2% of applied radioactivity.  Therefore, these residues are not considered to be bioavailable and binding to soils was considered a pathway for disappearance.

Results from simulation testing on degradation in sediment;

In accordance with ECHA Decision number: CCH-D-2114494377-34-01/F, the following studies were conducted for environmental fate:

• Sediment simulation testing (Annex IX, Section 9.2.1.4.; test method: Aerobic and anaerobic transformation in aquatic sediment systems, EU C.24./OECD TG 308) at a temperature of 12 °C with the registered substance

The results of this study are as follows:

The output values for the chosen model for each test system are presented in the table below.

Test system	Compartment	Model	r^2	χ^2(%)	DT90 at 12°C (days)	DT50 at 12°C (days)
HOC	Overlying water	SFO	0.9967	7.36	11.1	3.35
	Sediment extracts	HS	0.9938	5.94	90.2	43.2
	Total system	HS	0.9969	3.51	82.2	37.5
LOC	Overlying water	SFO	1.0000	nd	43.9	13.2
	Sediment extracts	SFO	0.6990	23.2	165	49.7
	Total system	SFO	0.7792	20.1	135	40.6

nd: not determined

[¹⁴C]4-(1-methyl-1-phenylethyl)-N-[4-(1-methyl-1-phenylethyl)phenyl]aniline dissipated over time from the water phase to the sediment phase in both sediment types, with overlying water DT_{50 ­}values of 3.35 and 13.2 days in the HOC and LOC test systems respectively.  [¹⁴C]4-(1-methyl-1-phenylethyl)-N-[4-(1-methyl-1-phenylethyl)phenyl]aniline degraded more rapidly in the HOC sediment than the LOC sediment, with total system, reflected in the total system DT₅₀ values of 37.5 and 40.6 days respectively.

Almost no mineralisation occurred, with <1% measured in both the HOC and LOC systems on Day 101.

8.8% and 7.6% of applied radioactivity remained in the sediment on Day 101 as bound radioactivity in the HOC and LOC test systems respectively after all extractions had been carried out.  ASE extractions removed less than 10% of applied radioactivity.  Therefore, these residues are not considered to be bioavailable and binding to sediments was considered a pathway for disappearance.

Other information, such as information from field studies or monitoring studies, provided that its suitability and reliability can be reasonably demonstrated.

Assessment of the propensity of the substance to abiotically degrade is available and is as follows:

Method

Results

according to guideline OECD Guideline 111 (Hydrolysis as a Function of pH) ; according to guideline EU Method C.7 (Degradation: Abiotic Degradation: Hydrolysis as a Function of pH) ; according to guideline EPA OPPTS 835.2120 (Hydrolysis of Parent and Degradates as a Function of pH at 25°C)

Half-life (DT50): t1/2 (pH 4): 53 d at 20°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 4): 26 d at 25°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 4): 25 h at 50°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 4): 11 h at 60°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 7): 25 d at 20°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 7): 14 d at 25°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 7): 24 h at 50°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 7): 16 h at 60°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 9): 18 d at 25°C; Type: (pseudo-)first order (= half-life) t1/2 (pH 9): 34 d at 20°C; Type: (pseudo-)first order (= half-life) Recovery (in %): Transformation products: not measured

The substance demonstrates a propensity towards degradation via abiotic routes.

The substance is not considered to be persistent within the environment. 

 

The substance has been demonstrated to have a very high partition coefficient value which demonstrates that the potential for this substance to accumulate biologically is limited, given that it is a high value of log P = 7.90 ± 1.22 (25°C, pH = 6.9). The high log Pow is considered to be more a consequence of poor water solubility issues than a lipophilic tendency and is considered to be not indicative of the tendency to bioaccumulate in lipid tissues of aquatic organisms. This is based on literature data which demonstrates a tendency for the Bioconcentration Factor (BCF) to decrease as Log Pow increases above 6. At a high value of 7.9, the substance is proposed not to bioaccumulate.  This is further confirmed via the use of the following QSAR tools: 

     

• CAESAR BCF Read-Across (version 1.0.0) 

 

• US EPA On-Line EPI Suite™v3.01 model BCFBAF 

 

    Which indicates that the substance is unlikely to bioaccumulate, with calculated values as follows: 

     

	BCF value (L/kg wet-wt)	Log BCF value
BCF Read-Across (version 1.0.0)	888	2.95
US EPA On-Line EPI Suite™v3-01 model BCFBAF	1245	3.095

  

 This QSAR prediction is supported by a radiolabelled toxicokinetic study on the substance. Within this study,14C radiolabelled test material was not extensively distributed into tissues of rats after an oral dose. The substance did not demonstrate high absorption from the gastrointestinal tract. And after 72h, the concentrations in the majority of tissues had decreased significantly. The above factors indicate that bioaccumulation within body tissues is unlikely.  

 

 Adsorption to soil is deemed to be high, based on the high associated test results. Such potential indicates that the substance is likely to bind tightly to soils and sediments and not partition at high levels in water. As such, significant exposure related effects to water dwelling organisms are considered to be negligible. The substance was not hazardous to terrestrial organisms in a variety of tests and is not considered to pose a hazard overall to the environment.   

 

Finally, the substance demonstrates low acute toxicity in mammalian studies. As it also is not anticipated to bioaccumulate, based on QSAR assessments and no persistency effects. In the event of exposure to higher level organism via ingestion of environmental organisms, effects due to secondary poisoning can be excluded. 

 

 Reliability. 

 

 The studies have all been ranked reliability 1 according to the Klimish et al system. This ranking was deemed appropriate because the studies were all conducted to GLP in compliance with recognised guidelines. 

 

 Justification for classification or non classification 

 

  The substance was originally self-classified as H413.  Following results of the OECD 210, 211 and enhanced biodegradation study, the substance can be considered to be not persistent or have chronic toxicity NOECS > water solubility.  On these grounds there is sufficient evidence to remove the Category 4 classification from the self-classification.

  

 CLP Regulation (EC No 1272/2008): Not classified.