Dimethyl sulphate

Partition coefficient

Administrative data

Endpoint:

partition coefficient

Type of information:

(Q)SAR

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Justification for type of information:

QSAR prediction: migrated from IUCLID 5.6

Data source

Reference

Reference Type:

publication

Title:

EPI Suite v4.00 - KOWWIN v1.67

Author:

Meylan, W.M. and Howard, P.H.

Year:

1995

Bibliographic source:

United States Environmental Protection Agency, Copyright 2000-2008 / http://www.syrres.com/esc/physdemo.htm

Materials and methods

Test guideline

Guideline:

other: REACH guidance on QSARs R.6, August 2008

Principles of method if other than guideline:

The Partition coefficient is the ratio of concentrations of a tested substance in a liquid consisting of two immiscible solvents at equilibrium. The n-octanol/water partition coefficient (Kow) is one of the key physico-chemical parameters, and it is used in numerous estimation models and algorithms for environmental partitioning, sorption, bioavailability, bioconcentration/bioaccumulation and also human- and ecotoxicity. As such Kow is a critical parameter for Chemical Safety Assessment (CSA), Classification and Labelling (C&L), and PBT assessment.

The program EpiSuite 4.0 (KOWWIN) predicts logPow values. Up to 89.1 % of the predicted values are within the +/-0.5 log unit of the measured logPow value (standard error of. 0.34 log unit).

GLP compliance:

not specified

Type of method:

other: estimated value (KOWWIN v1.67)

Partition coefficient type:

octanol-water

Test material

Test material information

Constituent 1

Reference substance name:

Dimethyl sulphate

EC Number:

201-058-1

EC Name:

Dimethyl sulphate

Cas Number:

77-78-1

Molecular formula:

C2H6O4S

IUPAC Name:

dimethyl sulfate

Details on test material:

smiles notation: O=S(=O)(OC)OC
No further significant information on test material was stated.

Study design

Analytical method:

other: not applicable, estimated value

Results and discussion

Partition coefficient

Type:

log Pow

Partition coefficient:

0.16

Details on results:

The program EpiSuite 4.0 (KOWWIN v1.67) predicts logPow values. Up to 89.1 % of the predicted values are within the +/-0.5 log unit of the measured logPow value (standard error of. 0.34 log unit).

Any other information on results incl. tables

Total Training Set Statistics:

(i)            number in dataset = 2447

(ii)           correlation coefficient (r²) = 0.982

(iii)          standard deviation = 0.217

(iv)         absolute deviation = 0.159

(v)          average Molecular Weight = 199.98 g/mol

 

To be effective an estimation method must be capable of making accurate predictions for chemicals not included in the training set. Currently, KOWWIN has been tested on an external validation dataset of 10,946 compounds. The validation set includes a diverse selection of chemical structures that rigorously test the predictive accuracy of any model. It contains many chemicals that are similar in structure to chemicals in the training set, but also many chemicals that are different from and structurally more complex than chemicals in the training set. The average molecular weight of compounds in the validation set is 258.98 versus 199.98 for the training set.

Total Validation Set Statistics:

(i)            number in dataset = 10946

(ii)           correlation coefficient (r²) = 0.943

(iii)          standard deviation = 0.479

(iv)         absolute deviation = 0.356

(v) average Molecular Weight = 258.98 g/mol

Applicant's summary and conclusion

Conclusions:

According to the reference, the partition coefficient n-octanol/water (log Pow) of DMS is calculated at 0.16.

Executive summary:

According to Annex VII section 7.8 Column 2 of regulation 1907/2006 this study does not need to be conducted for substances that decompose, which makes testing impossible. However, a calculated value as well as details of the calcuation method is provided to fulfill the requirements under REACH.