Naphthenic acids, reaction products with diethylenetriamine

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Naphthenic acids, reaction products with diethylenetriamine

EC Number:

268-610-1

EC Name:

Naphthenic acids, reaction products with diethylenetriamine

Cas Number:

68131-13-5

Molecular formula:

C16H21N3O2 (minimal)

IUPAC Name:

Naphthenic acids, reaction products with diethylenetriamine

Details on test material:

Product name MK195KSF
The test substance was received at Brixham Environmental Laboratory on 1 June 2010 and
assigned the Brixham test substance number 10-0152. The test substance (Batch Number
MK195K/BM/198/067/A/001) was supplied as a hazy solid. A certificate of analysis (dated
19 July 2010, Appendix 1) stated the sample had a purity/concentration of 100%.
The sample was stored in the dark, at ambient temperature, in the container in which it was
received until required for testing, when an appropriate subsample was provided for the test operator.

Sampling and analysis

Analytical monitoring:

not specified

Test solutions

Vehicle:

no

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Study design

Test type:

other: aerobic

Water media type:

brackish water

Total exposure duration:

3 h

Test conditions

Test temperature:

20+/-2°C

pH:

The pH was measured as 5.5, and was subsequently adjusted to 6.9 with 2 M sodium hydroxide prior to use.

Nominal and measured concentrations:

Nominal 1.0, 3.2, 10, 32 and 100 mg L-1 concentrations of MK195KSF

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Any other information on results incl. tables

The median effective concentration (EC50) is defined as the concentration, estimated from the data obtained, resulting in a 50% reduction in the respiration rate of activated sludge within the period of the test, and was estimated by the computer software, therefore, for MK195KSF,

3 hour EC50 >100 mg L-1

The 20% and 80% effect concentrations (EC20 and EC80) are defined as the concentrations, estimated from the data obtained, resulting in 20 and 80% reduction respectively in the respiration rate of activated sludge within the period of the test, therefore,

3 hour EC20 >100 mg L-1

3 hour EC80 >100 mg L-1

The 10% effect concentration (EC10) is defined as the concentration, estimated from the data obtained, resulting in a 10% reduction in the respiration rate of activated sludge within the period of the test. Percentage inhibition less than or equal to 10% was within the expected

experimental variability of the test and was considered not to be an effect of MK195KSF. The no observed effect concentration (NOEC) is therefore equivalent to the EC10 in this test, therefore,

3 hour NOEC = 100 mg L-1

The reference substance, 3,5-dichlorophenol, caused substantial inhibition of the respiration rate of the activated sludge. From the results obtained the 3 hour EC50 value was estimated to be 6.9 mg L-1 (Fig 1). This is within the expected normal range of 5 to 30 mg L-1 (Ref 1)

indicating the sludge was responding normally and confirming the viability of the sludge organisms. The respiration rates in the two control flasks were within 15% of each other.

Therefore, the mean control respiration rate was used in calculation of the percentage inhibition.

The temperatures in several flasks were below the required range of 20±2°C (minimum recorded 17.5°C). This slight deviation was considered not to have affected the validity of the study, as all the flasks were with 1ºC of each other.

Applicant's summary and conclusion

Conclusions:

3 hour EC50 >100 mg L-1
3 hour EC20 and EC80:
EC20 >100 mg L-1
EC80 >100 mg L-1
3 hour NOEC 100 mg L-1