Hexane-1,3,6-tricarbonitrile

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:

2022.08.25-2022.09.19

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test (Carbon and Ammonium Oxidation))

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

activated sludge

Details on inoculum:

For the preparation of the inoculum a sample of aerobic sludge has been selected by the mixed treatment plant of urban (about 66%) and industrial (about 34%) liquid sewage situated at San Rocco - Monza (MB), Italia. The plant of treatment is managed by “BRIANZACQUE SRL (Monza)”.

Activated sludge was collected and used on day of collection. No coarse particles were present so settling was not necessary. Then the mud samples, before their
use, were washed and analyzed to prepare the inoculum. The sludge was continuously aerated at the test temperature. The suspended solids in the mud solution was 3 g/L to have in the final mixture a concentration of 1.5 g/L.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20℃±2

pH:

7.47

Details on test conditions:

24 bottles were prepared for the test as follows:
- 3 different concentrations (1000, 100, 10 mg/L) for the test item at 3 replications/concentrations (9 bottles)
- 3 bottles for the blank control
- 3 different concentrations (50, 10, 1 mg/L) for the test reference (3,5-Dichlorophenol) at 3 replications/concentrations
(9 bottles)
- 3 bottles for abiotic control tested at the highest test item concentration (1 g/L).

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

- Blank controls oxygen uptake rate: 22.64 mg oxygen per one gram of activated sludge in an
hour.
- Coefficient of variation of oxygen uptake rate in control replicates: 1.48%
- EC50 of reference substance 3,5 — Dichlorophenol: 8.631 mg/L for total respiration

Results with reference substance (positive control):

Concentration Reference substance “3,5 - Dichlorophenol”
1 mg/L 11.68%
10 mg/L 50.25%
50 mg/L 86.16%

Validity criteria fulfilled:

yes

Conclusions:

The obtained results, in compliance with assay validity criteria, interpreted in accordance to OECD 209:2010, show that the EC50 value of the test item “HEXANE-1,3,6-TRICARBONITRILE”, after a contact time of 3 hours, results greater than 1000 mg/L.

Executive summary:

The aim of this study is to determine the effects of the test item “HEXANE-1,3,6-TRICARBONITRILE” on micro-organisms from activated sludge by measuring their respiration rate, according to OECD 209: 2010.

The respiration rates of activated sludge both in control, reference and treatment groups have been measured in an enclosed cell containing an oxygen electrode after a contact time of 3 hours at 20°C±2°C.

This method can be applied to water soluble, poorly water soluble and volatile substances.

The obtained results, in compliance with assay validity criteria, interpreted in accordance to OECD 209: 2010, show that the EC50 value of the test item “HEXANE-1,3,6-TRICARBONITRILE”, after a contact time of 3 hours, results greater than 1000 mg/L.

Key value for chemical safety assessment

EC50 for microorganisms:

1 000 mg/L