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Partition coefficient

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Endpoint:
partition coefficient
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
Since the substance itself was used also in the trainingsset of the QSAR tool, the prediction is in the applicability domain. Hence the QSAR tool is considered relevant and reliable for this substance.
Principles of method if other than guideline:
The established QSAR tool EPIwin v4.11 has been used.
GLP compliance:
no
Type of method:
other: QSAR calculation
Analytical method:
other: QSAR
Key result
Type:
log Pow
Partition coefficient:
2.03
Remarks on result:
other: QSAR result, not temperature and no pH reported.

KOWWIN Program (v1.68) Results:

===============================

 

Log Kow(version 1.68 estimate): 2.03

 

Experimental Database Structure Match:

Name    : MONURON

CAS Num : 000150-68-5

Exp Log P: 1.94

Exp Ref : HANSCH,C ET AL.(1995)

 

SMILES : O=C(N(C)C)Nc(ccc(c1)CL)c1

CHEM  : Urea, N'-(4-chlorophenyl)-N,N-dimethyl-

MOL FOR: C9 H11 CL1 N2 O1

MOL WT : 198.65

-------+-----+--------------------------------------------+---------+--------

TYPE | NUM |       LOGKOW FRAGMENT DESCRIPTION        | COEFF | VALUE

-------+-----+--------------------------------------------+---------+--------

Frag | 2 | -CH3   [aliphatic carbon]               | 0.5473 | 1.0946

Frag | 1 | -N<    [aliphatic attach]               |-1.8323 | -1.8323

Frag | 6 | Aromatic Carbon                          | 0.2940 | 1.7640

Frag | 1 | -CL    [chlorine, aromatic attach]      | 0.6445 | 0.6445

Frag | 1 | -N   [aliphatic N, one aromatic attach] |-0.9170 | -0.9170

Frag | 1 | -NC(=O)N-   [urea]                      | 1.0453 | 1.0453

Const |    | Equation Constant                        |        | 0.2290

-------+-----+--------------------------------------------+---------+--------

Log Kow  =  2.0281

Conclusions:
log Pow: 2.03
Executive summary:

The log Pow for monuron as calculated with the EPIwin v4.11 QSAR tool resulted in 2.03.

Since the substance itself was used also in the trainingsset of the QSAR-tool, the substance is in the applicability domain.

Hence the result is considered relevant and reliable for the further assessment of the substance.

Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
Data from QSAR-Tool EPIwin v4.11. No details were reported.
GLP compliance:
no
Type of method:
other: not reported
Partition coefficient type:
octanol-water
Analytical method:
not specified
Key result
Type:
log Pow
Partition coefficient:
1.94
Remarks on result:
other: Temperature and pH were not provided in the EPIwin data set.
Conclusions:
log Pow: 1.94
Executive summary:

In the EPIwin QSAR tool-box v4.11 a literature reference is made to Hansch et al. (1995). The experimentally determined log Pow is reported to be 1.94.

This result is considered relevant and reliable since the data base for the EPIwin QSAR-tool has been peer reviewed.

Endpoint:
partition coefficient
Type of information:
not specified
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
no information provided (information from data collection)
GLP compliance:
no
Type of method:
other: not specified since information from data collection
Partition coefficient type:
octanol-water
Analytical method:
not specified
Key result
Type:
log Pow
Partition coefficient:
1.94
Remarks on result:
other: Information on pH and temoerature were not provided
Conclusions:
log Kow 1.94
Executive summary:

In the data collection of RIVM prepared by van Bellen (2000), the log Kow of monuron is reported to be 1.94. It is indicated that this information has been obtained from MacKay D and Shiu M 1997, Illustrated handbook of physical-chemical properties and environmental fate for organic chemicals Vol. 5 Boca Raton, Floriday: Lewis publishers. Further details were not provided.

Considering the lack of information on how the log Kow of 1.94 was obtained, this value is considered to be usable for weight of evidence and not as stand alone information.

Description of key information

logPow: 1.94

Key value for chemical safety assessment

Log Kow (Log Pow):
1.94
at the temperature of:
20 °C

Additional information

An experimentally derived logPow of 1.94 and a logPow of 2.03 as derived from the EPIwin QSAR tool v4.11are available for monuron.

Both data are similar. The experimentally determined result is considered more relevant in the EPIwin-QSAR tool for the water solubility, i.e.. the logPow of 1.94 was used for the calculation of the water solubility.

Since the difference between both logPow data is small and using the more conservative result of 2.03 would not result in another classification/PBT-assessment, we followed the EPIwin logic and used the experimentally derived value as most relevant information. This is supported by the weight of evidence information from van Bellen (2000).