Mesitylene

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Non-GLP, near guideline, experimental study, published in peer reviewed literature; minor restrictions in design and/or reporting but otherwise adequate for assessment.

Qualifier:

according to guideline

Guideline:

other: In accordance with the “Provisional Procedure: extended toxicology test with Daphnia magna (determination of NOEC for reproduction rate, mortality and the time of first appearance of offspring; 21d)” as of 1 January 1984, Federal Environmental Agency.

Deviations:

not specified

Principles of method if other than guideline:

21 day semi-static closed vessel Daphnia reproduction test. Conducted in line with the provisional procedure proposed by the West German Federal Environmental Agency

GLP compliance:

no

Remarks:

No data reported

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
No data reported

Analytical monitoring:

yes

Details on sampling:

The concentration in the initial preparations and in the test and blank (no test organisms or feed) preparations were determined after 48/72 hours. Samples taken twice during the test period from selected concentrations and analysed, once before the 7th day and once between the 16th and 21st day.

Vehicle:

no

Details on test solutions:

Substances tested firstly fully diluted using magnetic stirrers for 24h. Graduated dilutions prepared from stock solutions.

Test organisms (species):

Daphnia magna

Details on test organisms:

20-30 specimens in forty 2-L beakers, filled with at least 1.6 L Berlin tap water. 24 h-old animals. Culture area regulated at 20°C.

Test type:

other: semi-static, closed vessels

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Post exposure observation period:

None

Hardness:

German hardness 16°

Test temperature:

25±1°C

pH:

pH was never lower than the 7.0

Dissolved oxygen:

Average minimum oxygen saturation value of 58%.

Salinity:

Not applicable

Nominal and measured concentrations:

Stock solution concentration: 63 mg/L.
Dilution steps corresponded to a ratio of 1:2.

Details on test conditions:

Four test vessels per concentration and four controls. 20 animals per concentration level. Feeding took place on the days when parent animals were transferred. Overall COD of 15-20 mg/L as the daily feed amount. Lit from 7am to 4pm with fluorescent lamps - Philips TL 40/25W.
Observations: Dead parent animals removed. Offspring counted, total number for each test vessel was recorded. pH value and oxygen concentration measured in two test vessels per concentration level.

Reference substance (positive control):

not specified

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.4 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

ca. 50 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Chemical analysis showed a loss of 1,3,5-trimethylbenzene of more than 20%. No chemical analysis was available for the 24h EC50.

Results with reference substance (positive control):

No data reported

Reported statistics and error estimates:

No data reported

Validity criteria met: reproduction rate per parent animal after 21 days was 68.0 offspring. Parent animal mortality after 21 days was 9.1%. The pH was never lower than the 7.0 in any of the control or test preparations. Average minimum oxygen saturation vale of 58%.

Validity criteria fulfilled:

yes

Remarks:

see remarks on results

Conclusions:

The minimum 21 day NOEC value was determined to be 0.4 mg/L based on chemical analysis. 1,3,5-trimethylbenzene was most sensitive to reproduction rate.

Executive summary:

This study is not GLP compliant but follows a standard guideline. There are limitations in the design and reporting but it is suitable for use for this endpoint. The minimum 21 day NOEC value was determined to be 0.4 mg/L based on chemical analysis. 1,3,5-trimethylbenzene was most sensitive to reproduction rate.

Description of key information

The 21 day NOEC value was determined to be 0.4 mg/L based on chemical analysis. 1,3,5-trimethylbenzene was most sensitive to reproduction rate.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.4 mg/L

Additional information

Based on the information available, the study by Kühn et al (1981) is considered to be the key study. The study is not GLP compliant but follows a standard guideline. There are limitations in the design and reporting but it is considered suitable for use as the key study for this endpoint. The 21 day NOEC value for Daphnia magna exposed to 1,3,5-trimethylbenzene was determined to be 0.4 mg/L based on chemical analysis. 1,3,5-trimethylbenzene was most sensitive to reproduction rate.