Reaction mass of carbon tetrachloride and chloroform and 1,2-dichloroethane

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The test was carried out under the conditions of GLP and according to the OECD Guideline for Testing of Chemicals No. 218 "Sediment-water chirnomid toxicity using spiked sediment", 2004.

Qualifier:

according to guideline

Guideline:

OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

SEDIMENT
- Sampling interval: single surrogate vessels were sacrificed at -6, 0, 7, 14, 28 days relative to addition of test animals
- Sample storage before analysis: 20 mL glass headspace autosampler vials, filled with 5 mL of a chilled matrix modifier solution; immediately sealed using PTFE-lined butyl rubber septa and aluminium crimp-caps; samples were refrigerated in the inverted position until analysed


OVERLYING WATER
- Sampling interval: single surrogate vessels were sacrificed at -6, 0, 7, 14, 21, 28 days relative to addition of test animals
- Sample storage before analysis: 20 mL glass headspace autosampler vials, filled with 5 mL of a chilled matrix modifier solution; immediately sealed using PTFE-lined butyl rubber septa and aluminium crimp-caps; samples were refrigerated in the inverted position until analysed

Vehicle:

no

Details on sediment and application:

The formulated sediment contained 70 % sand, 20 % kaolin clay, and 10 % sphagnum peat moss (dry weight ratios). The peat moss was conditioned prior to use by mixing with LDW for two days. The organic carbon content of the sediment mixture was 4.5 % (dry weight, by combustion), water content was 47 % wt., and the pH was 6.8. The target organic carbon content of 5 % wt, was selected because this is the upper limit of sediment OC content recommended in the TGD on Risk Assessment (ECB 2003).

Test organisms (species):

Chironomus riparius

Details on test organisms:

Obtained as egg masses from Environmental Consulting and Testing (Superior, Wisconsin, USA). Each egg mass was transferred to a plastic medicine cup containing 20 mL of laboratory dilution water. After 2 days, the larvae emerged and were transferred to glass bowls containing 5 mL of a green algae suspension (Ankistrodesmus falcatus, 4 * 10^7 cells/mL) per liter of dilution water. Bowls were maintained at 20 °C under a 16-hour light: 8-hour dark photoperiod in an incubator. Midges used in the study were 2-3 days post-hatch.

Study type:

laboratory study

Test type:

flow-through

Water media type:

freshwater

Type of sediment:

artificial sediment

Limit test:

no

Duration:

28 d

Exposure phase:

total exposure duration

Hardness:

58-66 mg/L CaCO3 in water control,
62 mg/L CaCO3 in highest test material treatment group

Test temperature:

19.6-20.9 °C

pH:

7.2-7.6

Dissolved oxygen:

6.3-7.9 mg/L

Salinity:

40-44 mg/L CaCO3 in water control,
40-43 mg/L CaCO3 in highest test material treatment group

Ammonia:

0.0 mg/L

Nominal and measured concentrations:

Nominal: 0 (control), 1.4, 2.8, 5.5, 11, 22 mg/kg (dry weight)
Measured TWA: 0, 0.58, 2.2, 4.5, 10.0, 20.4 mg/kg (dry weight)

Details on test conditions:

TEST SYSTEM
- Test container (material, size): 1-L glass vessels sealed with Teflon-lined screw caps
- Sediment volume: 110 mL
- Weight of wet sediment with and without pore water:
- Overlying water volume: 430 mL
- Depth of sediment and overlying water: 2 cm sediment, 8 cm water
- Aeration: no


EXPOSURE REGIME
- No. of organisms per container (treatment): 20
- No. of replicates per treatment group: 4
- No. of replicates per control / vehicle control: 4
- Feeding regime: daily
- Type and preparation of food: ground flake fish food suspension, TetraMin Flakes, Tetra Werke, Melle, Germany
- Amount of food: 2.5 mL of a 10 g/L solution


RENEWAL OF OVERLYING WATER
- Flow-rate: 10 volume-renewals per day


OVERLYING WATER CHARACTERISTCS
- Type of water (e.g. deionized, ground water, sea water, Elendt medium acc. to OECD 219): Lake Huron water supplied by the City of Midland Water Treatment Plant
- Alkalinity: 40-44 mg/L CaCO3
- Salinity:
- Conductivity: 166-178 umho/cm)
- Particulate matter:
- Total organic carbon: 390 ug/L
- Chemical oxygen demand:
- Unionized ammonia:
- Residual chlorine:
- Total organic chlorine compounds and PCBs:
- Total organophosphorous compounds:
- Total organic chlorine:


OTHER TEST CONDITIONS
- Light quality:
- Photoperiod: 16 hours light, 8 hours dark
- Light intensity: 536-909 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : midge emergence ratio and development rate

Reference substance (positive control):

no

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

10 mg/kg sediment dw

Nominal / measured:

meas. (TWA)

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

20.4 mg/kg sediment dw

Nominal / measured:

meas. (TWA)

Basis for effect:

emergence rate

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

20.1 mg/kg sediment dw

Nominal / measured:

meas. (TWA)

Basis for effect:

emergence rate

Remarks on result:

other: 7.9-32.4

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

4.5 mg/kg sediment dw

Nominal / measured:

meas. (TWA)

Basis for effect:

other: male development rate

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

10 mg/kg sediment dw

Nominal / measured:

meas. (TWA)

Basis for effect:

other: male development rate

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

10 mg/kg sediment dw

Nominal / measured:

meas. (TWA)

Basis for effect:

other: female development rate

Duration:

28 d

Dose descriptor:

LOEC

Effect conc.:

20.4 mg/kg sediment dw

Nominal / measured:

meas. (TWA)

Basis for effect:

other: female development rate

Reported statistics and error estimates:

Normality test: Shapiro-Wilk's test; if data not normally distributed, logarithmic, inverse, and square root, arcd sine square root transformations were tested
Test for homogeneity of variance: Bartlett's test at type I error rate of 0.01
Parametric analysis for normal and homogenous data: one-tailed Dunnett's test looking for a significant difference of test groups to control groups at a type I error rate of 0.05
Non-parametric analysis for not normally distributed and/or not homogenous data: Steel's Many-One Rank test if number of replicates in each treatment group the same or Kruskal-Wallis test if number of replicates different; both tests have a type I error rate of 0.05; a significant result in the Kruskal-Wallis test led to a pairwise comparison of each treatment with the control using the Wilcoxon procedure having a type I error rate of 0.01

Table 1: Midge emergence data

Nominal concentration of chloroform (mg/kg dw)	Repl. 1	Repl. 2	Repl. 3	Repl. 4
Control	90.0	85.0	100	100
1.4	100	90.0	95.0	90.0
2.8	85.0	100	95.0	90.0
5.5	95.0	90.0	85.0	100
11	80.0	100	85.0	95.0
22	40.0	35.0	10.0	35.0

Table 2: Midge development rate data

Nominal concentration of chloroform (mg/kg dw)	Repl. 1		Repl. 2		Repl. 3		Repl. 4
	Male	Female	Male	Female	Male	Female	Male	Female
Control	0.061	0.0492	0.0601	0.0485	0.0574	0.0486	0.0603	0.048
1.4	0.062	0.0501	0.0582	0.046	0.0616	0.0496	0.0597	0.0478
2.8	0.0634	0.0509	0.0582	0.0495	0.0578	0.0466	0.0589	0.0466
5.5	0.0585	0.0493	0.0609	0.0469	0.0605	0.0479	0.0603	0.0497
11	0.0552	0.0438	0.0529	0.0508	0.0551	0.0498	0.0547	0.0468

Validity criteria fulfilled:

yes

Conclusions:

The development rate NOEC and LOEC values for both the female midges and the pooled male/female midges were 10.0 and 20.4 mg/kg dw, respectively, based on sediment TWA concentrations, while the NOEC and LOEC values for the male midges were 4.5 and 10.0 mg/kg dw, respectively, based on sediment TWA concentrations.

Executive summary:

The study investigated the sediment ecotoxicity of chloroform in a 28 -days flow-through system with the midge, Chironomus riparius, according to the OECD Guideline No. 218 and in accordance with GLP standards. The study met all the validation requirements set out in the guideline.

The test vessels were loaded with formulated sediment, which was spiked with chloroform solutions seven days before the start of the test at different test concentrations. Chloroform solutions were applied to each sediment to maintain consistent test sediment concentrations.

The endpoints of interest were the proportion of larvae emerged (emergence ratio) and the development rate, which was the more susceptible endpoint in the test. Results were analysed with Dunnett's test to identify treatment effects at an alpha level of 0.05.

The development rate NOEC and LOEC values for both the female midges and the pooled male/female midges were 10.0 and 20.4 mg/kg dw, respectively, based on sediment TWA concentrations, while the NOEC and LOEC values for the male midges were 4.5 and 10.0 mg/kg dw, respectively, based on sediment TWA concentrations.

Description of key information

Two guideline-compliant long-term studies on the sediment organisms Chironomus riparius and Lumbriculus variegatus have been made available after their request under a EU RAR conclusion (i) program (Woodburn et al. 2006a, Woodburn et al. 2006b). The lowest NOEC of 4.5 mg/kg (dw) was found in the reliable study on midges (Woodburn et al. 2006a).

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater sediment:

4.5 mg/kg sediment dw

Additional information

No experimental study was conducted on the multiconstituent substance (Flux1). Instead, a constituent-based, Weight-of-Evidence approach, was performed.

The three major constituents were targeted, representing ca 95% of a typical composition (carbon tetrachloride (CAS n° 56-23-5),1,2-Dichloroethane (CAS n°107 -06 -2) and chloroform (CAS n° 67-66 -3)). Of the three, only data on chloroform

were available.

Two recent studies on the sediment toxicity of chloroform had a test period of 28 days.

The study on the midge Chironomus riparius followed the OECD Testing Guideline No. 218 with particular precautions to avoid chloroform volatilisation during the test period (Woodburn et al. 2006 a). The monitoring of the concentrations of chloroform in the overlying water and the sediment revealed good maintenance during the 28-day period of the test. The endpoints of interest in the study were the proportion of larvae emerged (emergence ratio) and the development rate. The development rate of the male midges turned out to be the most sensitive endpoint under investigation. The 28-day NOEC and LOEC values for the male development rate were 4.5 and 10.0 mg/kg (dw), respectively.

The study on the oligochaete, Lumbriculus variegatus, followed a proposed OECD guideline, because no finalised standard guideline was available at the time of the study (Woodburn et al. 2006 b). Over the 28-day exposure period, a good reproducibility in sediment concentrations and overlying water concentrations could be observed. The endpoints of interest in the study were the total number of live worms, the reproduction and the worm biomass. The NOEC and LOEC values for these three endpoints together were 19.2 and 36.9 mg/kg (dw), respectively.

The lowest NOEC has been determined in the guideline-compliant study on Chironomus riparius: 4.5 mg/kg (dw). The PNEC for the sediment that is derived from this NOEC (by applying a factor of 10) is 450 microgram/kg (dw). This is considerably lower than the PNECsediment (dw) derived in the draft European Union Risk Assessment Report by using the equilibrium partitioning method, which is 702 microgram/kg (ww) and 3230 microgram/kg (dw) (COM 2007).