2,4,6-trinitrotoluene

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: slightly changed method than that used by OETKEN et al. (2001), which is based on OECD 218 (OECD, 2000)

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

SEDIMENT
- Amount: 120 g (dw)
- Sampling interval: at the beginning (start of exposure) and end of the experiment

PORE WATER
- Amount: 10 mL
- Sampling interval: at the beginning (start of exposure) and end of the experiment

OVERLYING WATER
- Amount: 300 mL
- Sampling interval: at the beginning (start of exposure) and end of the experiment

Vehicle:

yes

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Method of mixing: Quartz sand and food source were mixed in dry state. Sediment measuring 135 g was placed into each beaker. After application of the test substance (see below for details) 30 ml of dechlorinated active carbon filtered tap water was carefully filled onto the sediment to wet the sediment and its components. After one hour the rest of the overlying water (370 ml) was carefully filled on top of the sediment. The ratio of overlying water to sediment was 4:1.
- Details of spiking: test substance was dissolved in the solvent acetone to prepare a stock solution, and then diluted. Artificial sediments for each beaker were spiked separately with the same volume of solvent containing the appropriate amount of test substance for each concentration level. The volume of solvent used was as much as needed to cover the sediment completely. Sediment was mixed thoroughly after application of the solvent.
- Evaporation of vehicle before use: yes. The sediment was completely dried in the air stream of the exhaustion hood. Solvent was totally removed from the sand by this method. Then sediment was mixed again. Overlying water was added very carefully to avoid sediment disturbance.
- Equilibration time: Sediment aging period was 2 weeks to get an equilibrium between the freely dissolved substance in overlying and pore water and the particle-bound substance within the sediment, and to condition the food source within the sediment
- Controls: yes: Solvent controls: with treatment with solvent, Controls: without treatment with solvent

Test organisms (species):

Chironomus riparius

Details on test organisms:

TEST ORGANISM
- Source: received from Bayer AG Leverkusen in November 1999
- Age of parental stock: Freshly hatched larvae

ACCLIMATION
- Acclimation conditions: Cultured at 20°C. Larvae were kept in several 5 l glass aquaria containing an artificial quartz sand layer (grain size of 62 to 2000 mm) of 1 cm thickness and dechlorinated active carbon filtered tap water. The water was renewed every week. Sediment was thoroughly washed every 2 months.
- Type and amount of food: TetraMin, ad libitum
- Feeding frequency: three times a week

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Test temperature:

20 ± 1°C

pH:

8.02-8.65

Dissolved oxygen:

5.15 - 9.11 mg/L

Nominal and measured concentrations:

Concentrations were tested in the 28-day sediment toxicity test with C. riparius: 5.12, 12.8, 32, 80, 200 mg/kg TNT.

Analytical measurements were below the limit of quantification of 0.5 mg/kg for bulk except for one concentration each at the start and end of the exposure period. The arithmetic mean of measurements in bulk of the start and end of the exposure period was approximately 0.5% of nominal concentrations. Analytical measurements were below 80% of the nominal spiked concentrations at the start of the exposure period. Therefore, calculated nominal ECX and NOEC/LOEC values were corrected and recalculated. Effective concentrations based on analytical measurements could not be calculated properly due to little analytical data, as described above. Effective concentrations based on measurements of TNT are roughly lower by a factor of 200 than nominal concentrations.

Details on test conditions:

TEST SYSTEM
- Test container: Beakers measuring 2000 ml with sediment to overlying water volume ratio of 1:8 were used.
- Sediment volume: Quartz sand with a defined grain size ranging from 62 - 2000 mm was used. The organic carbon within the sediment was made up of shredded leaves of alder (A. glutinosa) and nettle (U. dioica), which were a complete food source for the test organisms. The amount of alder and nettle leaves was 2%, which served as a complete food source for the larvae. Sediment aging period 2 weeks.

EXPOSURE REGIME
- No. of replicates per treatment group: 10
- No. of replicates per control / vehicle control: 10

OVERLYING WATER CHARACTERISTCS
Dissolved oxygen, pH, and conductivity were measured in all beakers at the start and end of the test.

CHARACTERIZATION OF ARTIFICIAL SEDIMENT
Quartz sand with a defined grain size ranging from 62 - 2000 mm was used. The organic carbon within the sediment was made up of shredded leaves of alder (A. glutinosa) and nettle (U. dioica), which were a complete food source for the test organisms.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours of light and 8 hours of dark.

EFFECT PARAMETERS MEASURED :
Beakers were checked for emerged midges daily. Sex and dry weight were determined. Development rate, which is the reciprocal of EMT50 (time at which 50% of the organisms emerged), and emerging rate were calculated.

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

80 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: development rate female and male, emergence

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

200 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: development rate female and male, emergence

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

98.3 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks:

male and female

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

269.9 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks:

male and female

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

200 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: emergence female, emergence male, individual dry weight female and male

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

80 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: total dry weight female

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

200 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: total dry weight female and male

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

6.75 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: total dry weight female

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

1 170 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: total dry weight female

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

ca. 0.4 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: development rate female and male, emergence

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

ca. 1 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: development rate female and male, emergence

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

ca. 0.5 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: emergence female and male

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

ca. 1.3 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: emergence female and male

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: emergence female, emergence male, individual dry weight female and male

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

ca. 0.4 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: total dry weight female

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

ca. 1 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: total dry weight female

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

EC10

Effect conc.:

ca. 0.03 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: total dry weight female

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

ca. 5.8 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: total dry weight female

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

ca. 1 mg/kg sediment dw

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: total dry weight male

Remarks on result:

other: measured conc. for TNT by appr. factor 200 lower than nominal conc., most measurements below limit of quantification except for one concentration each for t0 and t28. Effective concentrations could not be calculated properly due to little analytical data.

Emergence

Total emergence of C. riparius (the sum of male and female midges) was significantly reduced according to the Williams test (p = 0.05) in the 200 mg/kg treatment compared to pooled controls. NOEC/LOEC values of 80/200 were derived for the endpoint total emergence of the sum of male and female midges. An EC10 of 98.3 mg/kg and an EC50 of 269.9 mg/kg were calculated using probit analysis for the endpoint total emergence.

A shift in time at which emergence occurs is significant if significant differences are observed for development rates. Emergence was reduced in the 200 mg/kg treatment and midges emerged later than controls and solvent controls. This delay is supported by the significantly lower development rate of midges exposed to this concentration.

Development rate

Development rates of male and female midges were significantly reduced compared to pooled controls in the 200 mg/kg treatment. For the endpoint development rate of both male and female C. riparius, NOEC/LOEC values of 80/200 mg/kg were derived.

Biomass

Individual body dry weight of both male and female C. riparius was not significantly different in any treatments compared to pooled controls. NOEC/LOEC values of 200/- mg/kg were derived. No significant effects were observed on individual dry weight up to the highest tested concentration.

For the endpoint total biomass of male C. riparius, no significant difference was observed. For total biomass of female C. riparius, NOEC/LOEC values of 80/200 mg/kg were derived. An EC10 of 6.8 mg/kg and an EC50 of 1170 mg/kg were calculated using probit analysis for the endpoint total dry weight of female midges. ECX could not be calculated for male midges due to mathematical reasons.

Validity criteria fulfilled:

yes

Conclusions:

The sediment test on Chironomus riparius resulted in the following ECx and NOEC/LOEC values:
- based on nominal concentrations: EC10 6.75 mg/kg dw (total dry weight female) , EC10 98.3 mg/kg dw (emergence male and female), EC50 1170 mg/kg dw (total dry weight female), and EC50 269.9 mg/kg dw (emergence male and female), Lowest NOEC/LOEC (development rate, emergence male and female, total dry weight female): 80/ 200 mg/kg dw .
- lowest effective concentrations based on measurements: EC10 ca. 0.03 mg/kg dw (total dry weight female) , EC10 ca. 0.5 mg/kg dw (emergence male and female), EC50 ca. 5.8 mg/kg dw (total dry weight female), and EC50 ca. 1.3 mg/kg dw (emergence male and female), Lowest NOEC/LOEC (development rate, emergence male and female, total dry weight female): ca. 0.4/ ca. 1 mg/kg dw .

Description of key information

The sediment test on Chironomus riparius resulted in the following ECx and NOEC/LOEC values:
- based on nominal concentrations: EC10 6.75 mg/kg dw (total dry weight female) , EC10 98.3 mg/kg dw (emergence male and female), EC50 1170 mg/kg dw (total dry weight female), and EC50 269.9 mg/kg dw (emergence male and female), Lowest NOEC/LOEC (development rate, emergence male and female, total dry weight female): 80/ 200 mg/kg dw.

Key value for chemical safety assessment

EC50 or LC50 for freshwater sediment:

269.9 mg/kg sediment dw

EC10, LC10 or NOEC for freshwater sediment:

80 mg/kg sediment dw