m-toluic acid

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

1998

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

50 ml water samples for concentration measurement of m-toluic acid were taken. The test concentrations were measured for both renewal and old test solution at the start of test and 2nd, 6th 8th, 14th and 16th day.

Vehicle:

no

Details on test solutions:

A stock solution was prepared in dechlorinated tap water. No further information given.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: Test organisms were obtained from the National Institute for Environmental Studies (Japan)
- Age of parental stock: 2-4 weeks
- Age at test initiation: < 24 h
- Feeding during test
- Food type: Chlorella vulgaris
- Amount/Frequency: approx. 0.15 mg C (organic carbon) per daphnia per day

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

87-88 mg/L

Test temperature:

19.2 - 20.8 °C

pH:

6.8 - 8.2

Dissolved oxygen:

7.6 -9.6 mg/L

Nominal and measured concentrations:

Nominal concentrations: 0 (control), 1.0, 2.2, 4.6, 10, 22 and 46 mg/L

- Low concentration 1.0 mg/L: The test was carried out three times in parallel, the recovery rate was 100.7%, 99.7%, 100.8% (average 100.4%).
- High concentration 46.0 mg/L: The test was carried out three times in parallel, the recovery rate was 100.1%, 98.3%, 98.6% (average 99.0%).

Details on test conditions:

TEST SYSTEM
- Test vessel:100 mL glass jar with glass screw cap filled with 80 mL test solution
- Renewal rate of test solution (frequency/flow rate): every 48 h
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 1

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

OTHER TEST CONDITIONS
- Photoperiod: 16:8 hours, light-darkness


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
reproduction rate

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

9.7 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

22 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

15 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

LC50

Effect conc.:

> 46 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

>= 46 mg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Calculated based on measured concentrations, because some of the measured concentration were less than 80% of the nominal.

NOEC or LOEC was determined based on the cumulative number of juveniles produced per adult alive for 21 days. 1.0 and 2.2 mg/L indicate a significant difference from the control by Dunnett type multiple comparisons procedure, one-side test. However these results were judged that there was nothing under the influence by this substance because no significant difference at 4.6 and 10 mg/L.

Results with reference substance (positive control):

The test was carried out with potassium dichromate, EC for 48 hours was 0.49 mg /L (carried out on November 17, 1999) and 0.75 mg /L
(Implemented on May 16, 2000).

Reported statistics and error estimates:

a) Data Analysis: Dunnett multiple comparison for NOEC and LOEC
b) Method of Calculating Mean Measured Concentrations: Arithmetic Mean or Time-weighted Mean

Table 1: Cumulative numbers of juveniles produced per adult alive for 21 days

Vessel No.	Cont.	1 (0.542)	2.2 (1.5)	4.6 (4.12)	10 (9.74)	22 (22.1)	46 (45.9)
1	121	122	117	109	122	3	0
2	103	98	100	115	103	8	0
3	110	105	118	111	117	3	0
4	110	94	103	112	110	5	0
5	114	111	100	114	98	6	0
6	129	110	106	113	115	7	0
7	116	104	120	108	120	3	0
8	116	106	102	107	113	4	0
9	106	112	96	113	119	2	0
10	118	104	108	114	107	2	0
Mean	114.3	106.6	107	111.6	112.4	4.3	0
S.D.	7.6	7.8	8.5	2.8	7.8	2.1	0
Inhibition rate (%)	--	6.7	6.4	2.4	1.7	96.2	100
Significant difference*1	--	*	*	NS	NS	**	--

*1: Indicates a significant difference from the control by Dunnett type

multiple comparisons procedure, one-side test.

*: Significant (p<0.05)

**: Significant (p<0.01)

NS: Not significant (p>=0.05)

Table 2: Cumulative number of died parental daphnids

Nominal Conc. (mg/L)	Cumulative Number of Died Parental daphnids (days)
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21
Control	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
1	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
2.2	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
4.6	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
10	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
22	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
46	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0

Validity criteria fulfilled:

yes

Conclusions:

Daphnia magna neonates (< 24 h old) were exposed to m-toluic acid in dechlorinated tap water in a GLP-conform chronic reproduction test according to OECD TG 211. Mortality was not observed in the control or at any of the tested concentrations (LC50 >46 mg/L; NOEC >= 46 mg/L). A reduction of offsprings was observed at 22 mg/L (LOEC) after 21 days; the corresponding NOEC amounts to 9 mg/L (all measured TWA).

Description of key information

In a GLP-conform OECD 211 chronic reproduction test with Daphnia magna, effects on reproduction were observed at 22 mg m-toluic acid/L. The corresponding NOEC amounts to 9.7 mg/L m-toluic acid (measured).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

9.7 mg/L