m-toluidine

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:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Concept NEN report 6502 from the Dutch Standard Organization (1980)

Deviations:

yes

Remarks:

: Exposure time and number of organisms per group

Principles of method if other than guideline:

additionally: Canton et al. (1975)

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

-Only the lowest and highest tested concentrations were measured by GC

Vehicle:

not specified

Details on test solutions:

- were prepared in "Dutch Standard water", (DSW, Canton and Sloff, 1982)

Test organisms (species):

Daphnia magna

Details on test organisms:

-Age at study initiation: <1d

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

16 d

Remarks on exposure duration:

3-4 broods

Hardness:

ca. 1 mmol/L

Test temperature:

18-20°C

Nominal and measured concentrations:

ration of concentrations: 3.2

Details on test conditions:

-test volume per vessel: 1 L
-number of replicates per concentration: 2
-renewing rate: 3 times a week
-15 daphnids per vessel
-feeding with chlorella spec.

Reference substance (positive control):

not specified

Duration:

16 d

Dose descriptor:

EC50

Effect conc.:

0.043 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other: corrected for measured recoveries

Duration:

16 d

Dose descriptor:

EC50

Effect conc.:

0.038 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

NOEC ist not reported.

Validity criteria fulfilled:

not specified

Remarks:

Since the test is poorly reported the validity criteria cannot be assessed sufficiently. Nevertheless the test is considered as valid based on the data given.

Description of key information

The long-term toxicity of m-toluidine towards invertebrates was

investigated in a 21 d assay. A NOEC of 0.01 mg/L for reproduction was observed.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.01 mg/L

Additional information

Three long-term toxicity studies of m-toluidine to aquatic invertebrates are available.

First, the long-term toxicity of m-toluidine towards invertebrates was investigated in a 16 d assay. A NOEC of 0.012 mg/L was observed having the growth of the test animals as endpoint. The method used was NEN 6502 standard protocoll from the Dutch Standard Organization (1980) which follows the general principles of the OECD TG 202 (1984): Daphnia sp., Acute Immobilisation Test and Reproduction Test.

Daphnids were reared at a laboratory, and were less than 24 hours old at the start of the experiment. Stock solutions were prepared in ethanol. Test solutions were prepared in "Dutch Standard Water" (DSW). Daphnids in blanks were exposed to 100 µl/L ethanol. Concentrations of the test substance increased with a factor of 1.8. At the start of the experiment 20 -25 daphnids were placed into 1 L of the test solution under semi-static conditions. After 16 d of exposure to the test solutions, the length of each daphnid was determined. NOEC was determined using Student's test, and was defined as the highest concentration tested that did not give a singnificant (P < 0.05) decrease of length in duplicate experiments. EC10 was determined by minimum logit-X2 analysis. Due to a high deviation in length for concentrations lower or around NOEC, the value of NOEC and EC10 are similar. The values are assumed to base on nominal concentrations as no analytical monitoring is described.

The study cannot be fully validated due to limited reporting. No information is given if the first young was born after a maximum of nine days in the controls and the average cumulative number of young per female in the controls after three broods, was >/= 20. Nevertheless, the test duration was 16 days and it is assumed that the test duration was long enough for the development of at least three broods and the number of young per female was > 20 animals. In conclusion the study is scored to be reliable and a weight of evidence approach is applied.

Second, a study was performed to assess the effects of the substance on the reproductive output of parthenogenetic Daphnia magna under semi static conditions. The study was conducted according to the OECD Guideline 202 ( Acute immobilisation Test and reproduction Test, 1984) by EA, Japan: "Investigation of the Ecotoxicological Effects of OECD High Production Volume Chemicals", Office of Health Studies, Environmental Health Department, Environment Agency, Japan.

Young female Daphnia, aged less than 24 hours at the start of the test, were exposed to five concentrations, nominally 0.010, 0.032, 0.1, 0.32 and 0.1 mg/L of the test substance dissolved in water. Stock solution was prepared with DMSO, resulting in a final concentration of 200 mg/L. Controls with and without this vehicle was taken for test. After a 21d-exposure period, the total number of living offspring produced per parent animal alive at the end of the test was assessed. The reproductive output of the Daphnia exposed to the test item was compared to that of the control in order to determine the Lowest Observed Effect Loading (LOEL) and the No Observed Effect Loading (NOEL). The values are based on nominal concentration as no analytical monitoring was performed. Additionally, the survival of the parent Daphnia and the time to production of first brood was determined. The present study shows deficiencies concerning test organisms. A validity criterion of the OECD TG 202 (1984) was that the average cumulative number of young per female in the controls after three broods, should be >/= 20. As the number of offspring solely accounts for 32 in the present study, the validity criterion set out by the guideline is just fulfilled, but based on experience the number of offspring per adult normally accounts for approx. 80 to 100 animals after 21 days of exposure. This validity criterion is adjusted in the OECD guideline 211, were the number of offspring per adult should account for 60.

In conclusion the study is scored to be reliable and a weight of evidence approach is applied.

Further, the effect of m-toluidine on inhibition of reproduction of Daphnia magna was investigated according the NEN 6502 from the Dutch Standard Organisation (1980). The concentration at 50% inhibition of reproduction (EC50) was calculated based on the added quantities as well as on experimental measured concentrations after 16 days of exposure.