Dichlobenil

Hydrolysis

Link to relevant study record(s)

Reference

Endpoint:

hydrolysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not stated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

other: BBA Merkblatt no. 55

Deviations:

yes

Remarks:

Test was stopped after 150 days rather than when 50 % of the test material had decomposed. This deviation complies with EPA Guideline 161-1

GLP compliance:

yes

Radiolabelling:

no

Analytical monitoring:

yes

Buffers:

- pH: 5, 7 and 9
- Type and final molarity of buffer:
- Composition of buffer:
pH 5: 0.1 mol/L potassium hydrogen phtalate and 0.05 mol/L sodium hydroxide
pH 7: 0.071 mol/L potassium hydrogen phosphate and 0.01 mol/L disodium hydrogen phosphate
pH 9: 0.1 mol/L boric acid, 0.1 mol/L potassium chloride and 0.1 mol/L sodium hydroxide

Details on test conditions:

TEST SYSTEM
- Type, material and volume of test flasks, other equipment used: closed, non-sterile, all glass vessels
- Sterilisation method: not applicable
- Lighting: none
- Measures taken to avoid photolytic effects: vessels kept in the dark

Duration:

150 d

Temp.:

22 °C

Initial conc. measured:

0.007 - 0.009 µg/L

Number of replicates:

2

Positive controls:

no

Negative controls:

no

Transformation products:

not measured

Key result

pH:

5

Temp.:

22 °C

DT50:

> 150 d

Key result

pH:

7

Temp.:

22 °C

DT50:

> 150 d

Key result

pH:

9

Temp.:

22 °C

DT50:

> 150 d

Details on results:

RECOVERIES OF TEST MATERIAL
- 7th September 1982: mean recovery 100 % (all pHs)
- 29th September 1982: mean recovery 102 % (all pHs)
- 7th December 1982: mean recovery 102.4 % (all pHs)
- 10th February 1983: mean recovery 100 % (all pHs)

Table 1: Results

	Concentration of test material (µg/mL)
Days after test start	pH 5	pH 7	pH 9
0	7.24	8.90	8.93
16	7.16	8.55	8.68
30	7.14	8.64*	8.65
60	7.04	8.57	8.55
90	7.20	8.58	8.30
150	6.83	8.24	8.18*

* based on one value as the other was regarded as an outlier

The coefficient of variation was calculated from the duplicate determinations and equals 1.6 %. The decomposition was tested, using the first order model, and was significant for all three pH values.

Validity criteria fulfilled:

not specified

Conclusions:

Under the conditions of the test, the hydrolysis of the test material was determined to be >150 days and the test material is considered to be hydrolytically stable.

Executive summary:

In a GLP compliant hydrolysis conducted in accordance with sound scientific principles and an acceptable guideline (BBA Merkblatt no. 55), the hydrolysis of the test material was determined. Under the conditions of the test, the half-life of the test material was determined to be >150 days at pH 5, 7 and 9 and the test material is considered to be hydrolytically stable.

Description of key information

The test material was determined to be a have a half-life of >150 days at pH 5, 7 and 9 and is considered to be hydrolytically stable according to a study performed in line with recognised guideline BBA Merkblatt no. 55.

Additional information

The key study (Buisman, 1988) was performed in line with GLP and a recognised guideline with a sufficient level of detail to assess the quality of the study. The study was performed to a good standard and was assigned a reliability score of 2 using the principle for assessing data quality as set out in Klimisch (1997) on the basis that the guideline followed was not a standardised guideline although sufficient for the purposes of this study.