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Environmental fate & pathways

Adsorption / desorption

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Reference
Endpoint:
adsorption / desorption: screening
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 121 (Estimation of the Adsorption Coefficient (Koc) on Soil and on Sewage Sludge using High Performance Liquid Chromatography (HPLC))
GLP compliance:
yes (incl. QA statement)
Type of method:
HPLC estimation method
Media:
soil/sewage sludge
Radiolabelling:
no
Test temperature:
25 +/- 1°C
Details on study design: HPLC method:
EQUIPMENT
- Apparatus: HPLC
- Detection system: DAD


MOBILE PHASES
- Type: Tetrahydrofuran/pure water (50%/50%)
- Experiments with additives carried out on separate columns: no
- Solutes for dissolving test and reference substances: methanol and Tetrahydrofuran


DETERMINATION OF DEAD TIME
- Method: by inert substances which are not retained by the column


REFERENCE SUBSTANCES
- Identity: acetanilide; methylbenzoate; tridimenol; linuron; 1,2,3-trichlorobenzene; phenanthrene


DETERMINATION OF RETENTION TIMES
- Quantity of test substance introduced in the column: 50µl



REPETITIONS
- Number of determinations: 3

Analytical monitoring:
yes
Key result
Type:
log Koc
Value:
> 10
Validity criteria fulfilled:
yes
Conclusions:
The logarithmic adsorption coefficient log Koc of the test item was extrapolated to be higher than 10.
Executive summary:

The logarithmic adsorption coefficient log Koc of the test item was extrapolated to be higher than 10.

Description of key information

Adsorption / desorption: logarithmic adsorption coefficient (log Koc) > 10

Key value for chemical safety assessment

Additional information

The high Log Koc determined is consistent with the very poor water solubility (< 0.1 mg/l, substance is considered to be insoluble for the purposes of classification and labelling and chemical safety assessment). It reflects the test item's tendency to avoid aqueous environements by adsorption to surfaces.

In terms of the environmental fate of the test item, the high Log Koc means that the test item shows only very limited mobility in any water compartment. The test item is immobile due to adsorption to surfaces. Moreover, it is considered to be not bioavailable due to its strong adsorption tendency. This fact is supported by the results of both the biodegradability study as well as those of the toxicological and ecotoxicological studies performed. As a consequence, due to the high adorption tendency of the test item, it does not pose any hazard with regard to transport and distribution in the environment.

A high adsorption tendency may pose hazards to sediment and soil dwelling organisms and hence may call for additional testing to elucidate toxicity towards these compartments. Moreover, since adsorption to biological surfaces might lead to irritation and corrosion, special emphasis should be laid on the determination of those endpoints. However, available data on

- toxicity to microorganisms (IUCLID5 section 6.1.7)

- skin irritation/corrosion (IUCLID5 section 7.3.1)

- eye irritation (IUCLID5 section 7.3.2)

clearly show that the test item is not hazardous with regard to these endpoints. Due to the limited amount of the test item to be produced and hence the limited information requirements and considering the results of all available ecotoxicological and toxicological studies, additional testing is not considered necessary as no negative effects on soil and sediment dwelling organisms are to be expected.