3,5-dimethylbenzoyl chloride

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

13 October 1992 - 15 October 1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

Principles of method if other than guideline:

In aqueous solution, DMBC is rapidly hydrolysed to 3,5-dimethylbenzoic acid (DMBA). Therefore it is essentially the toxicity of the hydrolysis product that is measured.

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

3,5-dimethylbenzoyl chloride

EC Number:

413-010-9

EC Name:

3,5-dimethylbenzoyl chloride

Cas Number:

6613-44-1

Molecular formula:

C9H9ClO

IUPAC Name:

3,5-dimethylbenzoyl chloride

Details on test material:

DMBC
Appearance: clear liquid
Storage conditions: in darkness at room temperature

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Test concentrations were verified by chemical analysis. Water samples (50 mL in duplicate) were taken from the control and each exposure level (replicates pooled) at 0 hours and 48 hours and sent for verification.

Test solutions

Vehicle:

no

Details on test solutions:

TEST WATER
Laboratory tap water filtered, dechlorinated and softened by passage through an Elga water purification system. The water passes through a high pressure sand filter to remove colloids and particulate matter and a high grade activated carbon filter to remove chlorine and any organic contaminants. A proportion of the supply then passes through a water softener before final reverse osmosis treatment to produce a highly purified water supply. The two grades of dechlorinated water are then remixed in the ratio of approximately 1:1 to give a supply with the desired water hardness. Batches of softened water were "aged" with aeration for at least 12 hours prior to use by re-circulating through a gravel filter bed. Chlorine levels remained below the limit of detection at all times.

TEST SUBSTANCE PREPARATION
The test substance was dissolved in test water by stirring with magnetic stirrers for 24 hours to give an initial stock solution of 180 mg/L (nominal concentration). Serial dilutions of this stock solution were prepared with test water to give the desired series of exposure levels.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Strain: Daphnia Magna Straus.
- Source: Institute National de Recherche Chimique Applique (IRChA), France.
- Age at study initiation (mean and range, SD): 1st instar. Gravid adults were isolated 24 hours prior to initiation of the test. Young daphnids produced overnight were used for testing.
- Method of breeding: Parthenogenesis.
- Feeding during test: No

ACCLIMATION
- Acclimation conditions (same as test or not): Brood stocks of Daphnia magna were cultured under a 16 h light, 8 h dark photoperiod at 20 ± 2°C in polypropylene vessels containing two litres of dechlorinated, softened and aged tap-water.
- Type and amount of food: suspension of mixed algae (predominantly Scenedesmus and Selenastrum sp.).
- Feeding frequency: Daily

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

154 mg CaCO3/L.

Test temperature:

21 °C

pH:

4.3 - 8.0

Dissolved oxygen:

7.9 - 8.6 mgO2/L

Salinity:

NDA

Nominal and measured concentrations:

The nominal test concentrations employed in this study were selected on the basis of results from a preliminary range-finding study.

Nominal test concentrations: 0.56, 1.0, 1.8, 3.2, 5.6, 10, 18, 32, 56, 100 & 180 mg/L
Measured test concentrations: 0.51, 0.94, 1.7, 3.3, 5.3, 9.5, 17, 30, 52, 94 & 160 mg a.i/L

Details on test conditions:

EXPOSURE CONDITIONS

Experimental design:
11 test concentrations plus one control each in duplicate (20 animals per test group).
Ten 1st instar Daphnia were placed at random in each glass jar containing 200 mL of prepared test medium or diluent water only as appropriate, to give a loading of 20 mL test solution per organism. The jars were loosely covered with aluminium foil to minimise evaporation losses.

Medium renewal:
Daphnia were exposed to the test or control conditions for a period of 48 hours without renewal of test media.

Environmental conditions:
Cultures were maintained at 21 °C under a photoperiod of 16 hours light, 8 hours dark and without supplementary aeration or feeding during the 48 hour exposure period.

Criterion of effect:
Daphnia were considered to be immobilised if they were unable to swim for approximately 15 seconds after gentle agitation.

EVALUATION OF DATA
EC„ values and 95 % confidence limits were calculated according to the method of Thompson and Well (Thompson, W.R. & Well, C.S., 1952, Biometrics 8; 51 - 54). The "no-effect level" is the highest concentration at which the incidence of immobilisation is equal to or less than 10 %.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

59 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: 95 % confidence limits 51 - 68 mg a.i./L

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

30 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Details on results:

Cumulative immobilisation data are given in Table 1. All results are expressed in terms of the calculated mean concentration of DMBC (based on measured values of DMBA), (see Table 2). Concentrations ranged from 90 - 104 % of nominal at 0 hours and 83 - 104 % of nominal at 48 hours (average, 94 % a.i).

Any other information on results incl. tables

Table 1 Cumulative Immobilisation Data for Daphnia magna Exposed for 48 hours to DMBC

Nominal Concentration of DMBC mg/L	Measured Concentration of DMBC mg a.i./L	Cumulative Immobilised Daphnia magna (initial population: 10 per replicate)
		24 hours				48 hours
		R1	R2	Total	%	R1	R2	Total	%
Control 0.56 1.0 1.8 3.2 5.6 10 18 32 56 100 180	Control 0.51 0.94 1.7 3.3 5.3 9.5 17 30 52 94 160	0 0 0 0 0 0 0 0 0 0 9 10	0 0 0 0 0 0 0 0 0 0 7 10	0 0 0 0 0 0 0 0 0 0 16 20	0 0 0 0 0 0 0 0 0 0 80 100	0 0 1 2 0 1 2 1 0 2 9 10	0 0 0 0 1 0 1 0 1 3 10 10	0 0 1 2 1 1 3 1 1 5 19 20	0 0 5 10 5 5 15 5 5 25 95 100

R1 = Replicate 1

R2 = Replicate 2

                                                                                             

Table 2 Measured Concentrations. Mean values and Percentages of Nominal

Nominal Concentration of DMBC mg/L	Number of Samples Analysed	Mean Measured Concentration of DMBC mg a.i./L	% Nominal
Control 0.56 1.0 1.8 3.2 5.6 10 18 32 56 100 180	2 2 2 2 2 2 2 2 2 2 2 2	- 0.51 0.94 1.7 3.3 5.3 9.5 17 30 52 94 160	- 91 94 100 103 95 95 94 94 93 94 89

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The 48 h EC50 (immobilisation) value for DMBC with Daphnia magna is 59 mg a.i/L.

Executive summary:

A study was performed to assess the acute toxicity of DMBC to Daphnia magna under static conditions.

The study was conducted in accordance with OECD Guideline for Testing of Chemicals No. 202, Part 1 and EEC Methods for the Determination of Ecotoxicity, EEC Directive 67/548 Annex V Part C.2 (841449/EEC).

Groups of twenty (10 per replicate), 1st instar Daphnia were exposed for 48 hours to mean measured concentrations of 0.51, 0.94, 1.7, 3.3, 5.3, 9.5, 17. 30, 52, 94 and 160 mg a.i./L of DMBC dissolved in water.

 

The incidence of immobilisation was recorded for each test and control group at 48 hours and the following values determined:

48 h EC50 59 mg a.i./L, with 95% confidence limits of 51 - 68 mg a.i/L.

The "no-observed effect level" at 48 h was 30 mg a.i/L.