Benzeneacetyl chloride, 2,5-dimethyl-

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:

14 Mar - 06 Sep 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Commission Directive 88/302/EEC; OfficialJournal of the EG L133 Part C. 11 (1988).

Version / remarks:

1988

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The respiration rate of the activated sludge is measured after a contact time of 3 hours. The respiration rate of the same activated sludge in the presence of various concentrations of the test item, under otherwise identical conditions, is also measured. The inhibitory effect of the test item at a particular concentration is expressed as a percentage of the mean of the respiration rates of two controls. An EC50 value is calculated from the respiration rates at different test item concentrations.

Vehicle:

no

Details on test solutions:

The test item has been added to about 130 mL deionized water and stirred overnight before testing (equilibration phase). After 16 hours of stirring, a white precipitate formed, which most likely is the free acid of the acid chloride.

Method: physico-chemical oxygen consumption
Controls: 3.5-Dichlorophenol, Purity 97%.
Test substance concentration: 1000, 1800, 3200, 5600 and 10000 mg/L
Reference compound concentration: 2.5, 5, 10, 20 and 50 mg/L

Test organisms (species):

activated sludge

Details on inoculum:

Type: mixed population of aquatic microorganisms (activated sludge)
Origin: aeration tank of a domestic sewage treatment plant (Municipal STP Cologne-Stammheim)
Date of collection: 2006-09-11

Pretreatment: aeration of the activated sludge, daily fed with synthetic medium pH of the suspension before application: 6.6

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Test temperature:

20 +/- 2 °C

pH:

7.2 to 7.7

Nominal and measured concentrations:

nominal: 1000; 1800; 3200; 5600; 10000

Details on test conditions:

Type of application: direct weighing
Test concentration of the activated sludge: 840.0 mg/L suspended solids
Stirring period of test item before start of incubation time: 16h
Incubation time: 3 hours with permanent aeration

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

3 340 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Details on results:

The substance showed 91.2 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/L. EC50 = 3340 mg/L (2750 - 4100 mg/L).The EC values are determined by probit analysis. Confidence limits (95 %) are given in brackets.

Validity criteria for the measurement of the bacterial toxicity:

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
In a 2004 international ring test organized by ISO using activated sludge derived from domestic sewage, the EC50 of 3,5-dichlorphenol was found to lie in the range 2 mg/L to 25 mg/L for total respiration. If the EC50 of 3,5-DCP does not lie in the expected range, the test should be repeated with activated sludge from another source.	EC50 of the control was = 8.3 mg/L	Yes
The test should be performed at a temperature within the range 20 ± 2°C.	The test was performed at 20 +/- 2 °C.	Yes
The specific oxygen consumption of the controls shall be reported.	The oxygen consumption of the controls is stated.	Yes

 

Validity criteria fulfilled:

yes

Remarks:

See 'Any other information on results incl. tables'.

Conclusions:

The substance showed 91.2 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/L.
EC50 = 3340 mg/L (2750 - 4100 mg/L). The EC values are determined by probit analysis. Confidence limits (95 %) are given in brackets.

Executive summary:

A study was performed to assess the toxicity of bacteria.

The study was conducted in accordance with the Commission Directive 88/302/EEC; Official Journal of the EG L133 Part C. 11 (1988) and OECD Guideline 209 "Activated Sludge, Respiration Inhibition Test" (1984).

The activated sludge was exposed to the test substance at different concentrations. The respiration rate of each mixture was determined after aeration periods of 3 hours.

The test item showed 91.2 % respiration inhibition of activated sludge at a test item concentration of 10,000 mg/L.

The EC50 is 3340 mg/L.

The effect value related to nominal concentration, since no analytical monitoring was performed.

Description of key information

The substance showed 91.2 % respiration inhibition of activated sludge at a test item concentration of 10000 mg/L. EC50 = 3340 mg/L (2750 - 4100 mg/L).The EC values are determined by probit analysis. Confidence limits (95 %) are given in brackets.

Key value for chemical safety assessment

EC50 for microorganisms:

3 340 mg/L