Zinc dodecyl hydrogen disulphate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

5 Nov 2014

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

no

GLP compliance:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION:
A stock solution was prepared at a concentration of 37.5 g/L in deionized water under stirring. This concentration corresponded to 10 g/L of active ingredient as required by the test guideline.
Test bottles were prepared with deionized water, synthetic sewage feed and different concentrations of test substance or reference substance.

Test organisms (species):

activated sludge

Details on inoculum:

- Inoculum: actived sludge collected from the treatment plant of urban (66%) and industrial (34%) liquid sewage located in San Rocco, Monza. Activated sludge was used up to two days after collection.
- Preparation of inoculum for exposure: Coars partcles present in the sludge were removed by settling for 10 miuntes. The mud samples were wahsed and analyzed to prepare the inoculum. The sludge was continuously aerated at the test temperature.
- Pretreatment: none
- suspended solids concentration: 1.5 g/L

Total exposure duration:

3 h

Post exposure observation period:

none

Nominal and measured concentrations:

0, 10, 100, 1000 mg/L (a.i)

Details on test conditions:

TEST SYSTEM
- Test vessel: glass bottles
- Aeration: yes
- No. of vessels per concentration (replicates): 3 for 3 concentrations
- No. of vessels per blank control (replicates): 3
- No. of vessels per referece substance (replicates): 3 for 3 concentrations
- Abiotic control (replicates): 3 at highest test concentration
- Biomass loading rate:

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water

OTHER TEST CONDITIONS
- Adjustment of pH:
- Photoperiod: no

EFFECT PARAMETERS MEASURED: dissolved oxygen

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

EC50 = 8.1 mg/L

Table 1. Inhibition of respiration rate - test substance (as active ingredient):

Concentration mg/L (active substance)	% if inhibition of respiration rate
10	3.84
100	32.25
1000	92.43

Table 2. Respiration inhibition - reference substance

Concentration mg/L (active substance)	% if inhibition of respiration rate
1	20.84
10	46.8
50	82.19

Description of key information

3h EC50 (activated sludge, domestic) >100 mg/L (respiration inhibition test, OECD 209)

Key value for chemical safety assessment

EC50 for microorganisms:

100 mg/L

Additional information

In general, alkyl sulfates show no toxic effects to auqatic microorganisms (HERA, 2002; OECD SIDS, 2005). One study on activated sludge respiration inhibition is available for C12-14 AS Zn (Z&S, 2014). Activated sludge originating from the mixed (urban/industrial) treatment plant were used. The 3-h EC50 value was determined to be >100 mg a.i./L (nominal concentration). Moreover, the test substance has been shown to be readily biodegradable according to OECD criteria.