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Endpoint:
sediment toxicity: long-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2005
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
Twenty grams (wet weight) of the prepared sediment was added to clean 60 mL glass vessels followed by 30 mL of groundwater drawn from an aquifer. After 24 hours of equilibration, 10 mature Lumbriculus (ca. 15 mm in length, 8 mg dry weight) were added to each vessel. Vessels were aerated for 5 minutes every day and the overlying water replenished with distilled water every two days. Each test concentration was replicated 6 times. LAS concentrations were measured at 0 and 28 days. After 28 days the sediment was removed and all live worms counted, blotted dry, and wet weighed prior to air drying for 48 hours to a constant dry weight.
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Liquid scintillation monitoring with and without HPLC.
Vehicle:
yes
Details on sediment and application:
Natural sediment was collected on Nov. 21, 1997 from ARC Study Centre, UK. The composition was 44% sand, 48% silt, and 8% clay. Total organic carbon content was 1.7%. Dried sediment samples were mixed with wet sediment for 1 hr. 10 +/-1 g samples of sediment were spiked with aliquots of LAS in dichloromethane (100 mg LAS/ml dichloromethane) and radiolabeled LAS. Samples were left overnight so the vehicle could evaporate. Unspiked sediment was used for control.
Test organisms (species):
Lumbriculus variegatus
Study type:
laboratory study
Test type:
semi-static
Water media type:
freshwater
Type of sediment:
natural sediment
Limit test:
no
Duration:
28 d
Exposure phase:
total exposure duration
Hardness:
250 mg/L CaCO3
pH:
8.0
Nominal and measured concentrations:
Nominal concentrations: 0, 50, 75, 100, 150 300 and 600 mg/kg dry weight
Measured concentrations (Sediment; at day 0): 0, 54, 79, 136, 170, 300 and 612 mg/kg
Measured concentrations (Sediment; at day 28): 0, 14, 30, 27, 50, 113 and 183 mg/kg
Measured concentrations (Overlying water; day 0): 0, 0.1, 0.2, 0.3, 0.4, 0.9 and 2.3 mg/L
Measured concentrations (Overlying water; day 28):
Details on test conditions:
Twenty grams (wet weight) of the prepared sediment was added to clean 60 mL glass vessels followed by 30 mL of groundwater drawn from an aquifer. After 24 hours of equilibration, 10 mature Lumbriculus (ca. 15 mm in length, 8 mg dry weight) were added to each vessel. Vessels were aerated for 5 minutes every day and the overlying water replenished with distilled water every two days. Each test concentration was replicated 6 times. LAS concentrations were measured at 0 and 28 days. After 28 days the sediment was removed and all live worms counted, blotted dry, and wet weighed prior to air drying for 48 hours to a constant dry weight.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : survival, reproduction, and biomass measurements at end of study
The mode of reproduction (architomy) necessitates the treatment of survival and reproduction as a single endpoint, i.e., number of organisms at test termination.

Reference substance (positive control):
no
Key result
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
81 mg/kg sediment dw
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: reproduction and survival
Key result
Duration:
28 d
Dose descriptor:
EC10
Effect conc.:
61 mg/kg sediment dw
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: reproduction and survival
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
105 mg/kg sediment dw
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
other: reproduction and survival
Key result
Duration:
28 d
Dose descriptor:
NOEC
Effect conc.:
82 mg/kg sediment dw
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Key result
Duration:
28 d
Dose descriptor:
EC10
Effect conc.:
98 mg/kg sediment dw
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
109 mg/kg sediment dw
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Details on results:
LAS half-life in aerobic sediment was approximately 20 days. This is shorter than studies conducted in the same sediment without worms (half-life of 38 days), most likely due to increased bioturbation due to worm activity.
Reported statistics and error estimates:
One-way ANOVA test was used on the mean measured concentrations. Dunnett's test was used to obtain NOEC and LOEC values. ToxCalc v5.0, Maximum Likelihood-Probit was used to analyse and plot the data.

There was a loss of between 15 and 78% of the LAS radioactivity over the duration of the test, which was attributed to mineralization of LAS by the worms and microorganisms present in the sediment (biodegradation).  Results are therefore based on the average of day 0 and day 28 measured sediment concentrations.  All results are shown in the following table.

                                    

Table 1: Effect concentrations for Lumbriculus variegatus during a 28 day exposure period in the sediment (Comber et al., 2006)

 

  Sediment Concentration (mg/kg dw)
Survival/ Reproduction Endpoint NOEC LOEC EC10 EC20 EC30 EC50
Based on nominal values 100 150 73 90 105 136
Based on measured day 0 values 136 170 117 131 142 164
Based on mean of days 0 & 28 values 81 110 61 73 83 105
Biomass endpoint NOEC LOEC EC10 EC20 EC30 EC50
Based on nominal values 100 150 93 108 120 144
Based on measured day 0 values 136 170 137 146 153 166
Based on mean of days 0 & 28 values 82 110 98 102 105 109
Validity criteria fulfilled:
yes
Conclusions:
In a long term toxicity study, the 28-day NOEC of linear alkylbenzene sulphonate for Lumbriculus variegatus for survival and reproduction was 81 mg/kg dw, based on the mean of day 0 and day 28 concentrations, with EC10 and EC50 values of 73 and 105 mg/kg sediment dw respectively. The NOEC for biomass was 82 mg/kg dw, based on the mean of day 0 and day 28 concentrations, with EC10 and EC50 values of 98 and 109 mg/kg dw, respectively
Executive summary:

The toxicity of linear alkylbenzene sulphonates (LAS) to freshwater benthic organisms ( Lumbriculus variegatus) was assessed during exposure to spiked sediment. Samples of natural sediment were spiked with test substance at concentrations of 50, 75, 100, 150, 300, and 600 mg/kg/dry weight. Test organisms (n=10) were exposed to test substance for 28 days. At the end of study, the organisms were observed for survival and biomass. The test substance half-life in aerobic sediment was approximately 20 days.

In a long term toxicity study, the 28 day NOEC of linear alkylbenzene sulphonate for Lumbriculus variegatus for survival and reproduction was 81 mg/kg dw, based on the mean of day 0 and day 28 concentrations, with EC10 and EC50 values  of 73 and 105 mg/kg dw, respectively. The NOEC for biomass was 82 mg/kg dw, based on the mean of day 0 and day 28 concentrations, with EC10 and EC50 values of 98 and 109 mg/kg dw, respectively

Endpoint:
sediment toxicity: long-term
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2005
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
The toxicity of linear alkylbenzene sulphonates (LAS) to freshwater benthic organisms (Caenorhabditis elegans) was assessed during exposure to spiked sediment. Juvenile worms of the first stage were exposed to test concentrations for 72 hours. After 72 hours, the test was stopped by heat-killing the worms at approximately 50°C for 15 minutes. Sublethal toxicity endpoints were determined for growth based on the body length of the test organisms, and fecundity by counting the number of eggs in the body of the test organisms (egg production), in addition to the proportion of gravid test organisms (≥1 egg inside the body).
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
Liquid scintillation monitoring with and without HPLC.
Vehicle:
yes
Details on sediment and application:
The test sediment contained 44% sand, 48% silt, and 8% clay, with 2% organic matter.
Test organisms (species):
Caenorhabditis elegans
Details on test organisms:
The test species is an infaunal bacterial feeder with a short life cycle, so 72 hrs (3 days) is considered a chronic test.
Study type:
laboratory study
Test type:
semi-static
Water media type:
freshwater
Type of sediment:
artificial sediment
Duration:
72 h
Exposure phase:
total exposure duration
Hardness:
250 mg/L CaCO3
pH:
8.0
Nominal and measured concentrations:
Nominal concentrations were in the range of 10-1000 mg/kg dw. The nominal concentrations were 10, 50, 100, 200, 300, 400, 500, 750 and 1000 mg/kg dw and controls.
Details on test conditions:
At the start of the test, ten juvenile worms of the first stage (270 ± 16 µm body length) were transferred to each test vial containing 0.75 g wet weight of spiked sediment mixed with 0.25 mL of a bacterial suspension. Five replicates were set up for each treatment, and the samples were incubated on a shaker at 20°C. After 72 hours the test was stopped by heat-killing the worms at approximately 50°C. The samples were mixed with an aqueous solution of rose Bengal to stain the worms for easier recovery. Sublethal toxicity endpoints were determined for growth based on the body length of the organisms, and fecundity by counting the number of eggs in the body of the test organism (egg production).
Reference substance (positive control):
no
Key result
Duration:
3 d
Dose descriptor:
EC10
Effect conc.:
275 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Key result
Duration:
3 d
Dose descriptor:
NOEC
Effect conc.:
200 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Key result
Duration:
3 d
Dose descriptor:
NOEC
Effect conc.:
200 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
fertility
Key result
Duration:
3 d
Dose descriptor:
NOEC
Effect conc.:
100 mg/kg sediment dw
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
reproduction
Remarks:
(egg production)
Details on results:
The test was regarded as valid as the fertility of the test organisms in the control was ≥ 80%.
Reported statistics and error estimates:
One-way ANOVA test was used on the mean measured concentrations. Dunnett's test was used to obtain NOEC and LOEC values. Sigma Plot 5.0 was used to analyze the data. For determination of ECx values, dose response curves (% inhibition to control) were fitted to the respective data using a sigmoidal plots, using logistic models (Sigma Plot 5.0, SPSS, Munich Germany, for the nematode data).

Table 1:  Effect concentrations for fertility and egg production in mg/kg (dry weight;nominal concentrations) of LAS in the sediment bioassay with Caenorhabditis elegans (Comber et al., 2004)

 Test Parameter  Nominal Sediment Concentration (mg/kg dw)
NOEC LOEC EC10 EC30
Growth 200 300 275  
Fertility 200 300   258
Egg Production 100 200   125
Validity criteria fulfilled:
yes
Conclusions:
The 3-day EC10 value of linear alkylbenzene sulphonate for Caenorhabditis elegans was 275 mg/kg sediment dw based on growth rate. The NOEC were 200, 200 and 100 mg/kg dry weight, based on growth, fertility and egg production, respectively
Executive summary:

The toxicity of linear alkylbenzene sulphonates (LAS), to Caenorhabditis elegans was assessed during exposure to spiked sediment. Samples of natural sediment were spiked with concentrations of 10, 50, 100, 200, 300, 400, 500, 750 and 1000 mg/kg dw mg/kg dw and controls.  Test organisms (n=10) were exposed to test substance for 3 days. The test organisms were observed for growth and reproduction during the exposure period. The EC10 value was 275 mg/kg sediment dw based on growth rate. The NOEC were 200, 200 and 100 mg/kg dry weight, based on growth, fertility and egg production, respectively.

Endpoint:
sediment toxicity: short-term
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
The aim of this study was to evaluate the effects of sediment-sorbed LAS on the marine mussel, Mytilus galloprovincialis, exposed to the sediments spiked with 132 mg/kg dry weight of LAS mixtures for 7 days. Four experiments were performed and the physiological parameters (filtration, oxygen uptake, nitrogen excretion) were measured on control and treated animals.
GLP compliance:
no
Analytical monitoring:
yes
Vehicle:
no
Details on sediment and application:
PREPARATION OF SPIKED SEDIMENT
- Source of sediment: Surface sediments (0-5 cm depth) were collected by a van Veen grab from the same area of mussels, in the south basin of the Venice lagoon and air dried.

- Prepration of sediment: Sediments were enriched in fine-particle fraction (sand = 7%). The natural sediment, 10 kg dry weight, was suspended in 50 L of deionized water, after a few minutes the suspension of water and fine sediment was separated from the sand and allowed to settle, giving 450 g of fine dry sediment, which was finally characterized in terms of grain size using the Coulter counting technique.

- Method of mixing: The desired LAS sediment spiking was developed on the basis of LAS sediment adsorption and desorption studies.

- Details of spiking: Sediments were repeatedly equilibrated with a water-LAS solution (100 g/L d.w.) at low concentrations (10-20 mg/L LAS in water) by stirring for 1-2 days after each addition of detergent. The sediment was then allowed to settle. After each addition, in order to estimate the partition of LAS between water and sediment, the LAS concentration in water was determined by the MBAS method and checked for some samples by HPLC. LAS additions were stopped when the LAS concentration in the analysed water was greater than 50% of the initial concentration. The sediments were washed twice with deionized water to remove excess LAS. Total recovery was achieved by centrifugation of the supernatant water for 15 min at 5500 rpm.

- Controls: LAS-free control sediments were also prepared, using the same method.

- Equilibration time: 1-2 days

- Chemical name of vehicle: No vehicle was used.
Test organisms (species):
other: Mytilus galloprovincialis
Details on test organisms:
TEST ORGANISM
- Common name: Mussels
- Source: Mussels were collected from a mussel cultivation area of the Lagoon of Venice, Italy
- Main axis length: 5.8 ± 0.3 cm
- Feeding during test: The mussels were fed daily with a suspension of Chaetoceros sp., reaching a concentration in the experimental tank of about 15000 cells/mL

ACCLIMATION
- Acclimation period: The animals were acclimatized in circulating sea water for 10 days and fed with a mixture of unicellular algae.
- Acclimation conditions: Yes, salinity both during acclimatization and experiments was kept at 35 ± 1%o and temperature was 18 ± 1°C.
Study type:
laboratory study
Test type:
semi-static
Water media type:
not specified
Type of sediment:
natural sediment
Limit test:
no
Duration:
7 d
Exposure phase:
total exposure duration
Nominal and measured concentrations:
50 mg/L continuously suspended LAS-spiked sediments
Details on test conditions:
TEST SYSTEM
- Test container: Net tubes in a 60 L tank
- Sediment volume: 50 mg/L dry weight

EXPOSURE REGIME
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 3
- No. of replicates per control: 3
- Type, amount of food and feeding regime: The mussels were fed daily with a suspension of Chaetoceros sp., reaching a concentration in the experimental tank of about 15000 cells/mL
- Additional information: After 24 hours, water, food and sediment were renewed and the removed water and suspended sediment were decanted into a large tank.

EFFECT PARAMETERS MEASURED:
1. Filtration rate of the molluscs: It was determined twice a day in the experimental tank: first after water change, then immediately before the next change.
2. Chlorophyll content: After renewal of sea water, sediment, food and water samples were analysed for chlorophyll content and sampling was repeated after 30, 60 and 120 minutes
3. Oxygen consumption rates: At the end of each treatment, it was determined for individual mussels in 12 flasks simultaneously. Filtered and air-saturated see water was added to each flask and oxygen concentration was measured initially and after 2 hours with an Orion Research O2 Electrode.
4. Ammonia excretion rate from the oxygen consumption flasks, using a proposed method by Koroleff (1983).
5. Organic matter determination: Faeces, separated from pseudofaeces by careful pipetting, were collected every 24 hours from the bottom of the net tubes and dried at 70C. Faeces deriving from 6 days for each group of ten animals were pooled to obtain a sufficient quantity for the analysis of LAS concentration and composition by HPLC. Faeces of the 7th day were collected for organic matter determination. They were rinsed with a solution of ammonium formate isotonic to sea water, drided at 90C, weighed, ashed at 450C and reweighed.

VEHICLE CONTROL PERFORMED: No
Reference substance (positive control):
no
Key result
Duration:
7 d
Dose descriptor:
NOEC
Effect conc.:
32.19 mg/kg sediment dw
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr.
Basis for effect:
other: filtration rate, oxygen uptake, nitrogen excretion
Remarks on result:
other: geometric mean of initial 132 mg/kg dry weight and final 7.85 mg/kg dry weight LAS concentration
Details on results:
- No significant differences in survival or physiological responses (filtration, oxygen uptake and nitrogen excretion) between treatments and controls were observed.

- The LAS concentration in treated sediments decreased by about 90% over the duration of the study (mean 132 mg/kg at initiation to mean 7.85 mg/kg at completion).
Reported statistics and error estimates:
Statistical comparison between control and treated mussels was done by non-parametric Wilcoxon's test.

Table 1: Physiological parameters in mussels treated with control (C1-4) and LAS contaminated (T1-4) sediments (Marin et al., 1994).

  Marine control sediment   Marine treated sediment 
  Experiment Number of mussels Mean Standard error Statistical comparison  Experiment Number of mussels Mean Standard error
Oxygen consumption (mL O2/g dw/h) C2 12 0.497 0.037 Not significant T2 12 0.511 0.020
  C3 12 0.582 0.061 Not significant T3 12 0.594 0.066
  C4 12 0.563 0.036 Not significant T4 12 0.631 0.040
Ammonia excretion (µgat N/g dw/h) C2 12 3.866 0.296 Not significant T2 12 3.767 0.139
  C3 12 4.151 0.345 Not significant T3 12 4.251 0.483
  C4 12 2.872 0.400 Not significant T4 12 3.115 0.532
Filtration A (1/animal/h)  C1 5 2.891 0.259 Not significant T1 5 2.554 0.195
  C2 5 3.042 0.225 Not significant T2 5 2.705 0.218
  C3 6 3.734 0.166 Not significant T3 6 3.540 0.107
  C4 5 3.165 0.222 Not significant T4 5 3.341 0.142
Filtration B (1/animal/h)  C1 5 3.083 0.253 Not significant T1 5 2.894 0.306
  C2 6 3.076 0.150 Not significant T2 6 2.852 0.304
  C3 6 3.165 0.310 Not significant T3 6 3.820 0.634
  C4 5 3.120 0.526 Not significant T4 5 3.326 0.511

Oxygen consumption and NH3 excretion were determined at the end of 7 days' treatments; daily filtration after (A) and before (B) sea water and sediment renewal. Statistical comparison between control and treated mussels was done by non-parametric Wilcoxon's test.

Table 2: LAS concentrations (mg/kg dry weight) in control and treated sediments, determined by HPLC (Marin et al., 1994).

  Marine control sediment Marine treated sediment
  B (before experiments) A (after experiments) B (before experiments) A (after experiments)
Sample size 3 4 4 4
Mean 4.76 1.3 132.04 7.85
Standard error 1.42 0.2 0.76 0.79
Validity criteria fulfilled:
not specified
Conclusions:
In a sediment toxicity study, no significant differences in physiological responses (filtration, oxygen uptake, nitrogen excretion) of treated Mytilus galloprovincialis was observed as compared to controls when test species was exposed to 132 mg/kg dry weight LAS. It shows the absence of a toxic action of LAS contaminated sediments.
Executive summary:

The aim of this study was to evaluate the effects of sediment-sorbed LAS on the marine mussel, Mytilus galloprovincialis.

Test species (n=30), divided into groups of 10, were exposed to the sediments spiked with 132 mg/kg dry weight of LAS mixtures for 7 days. Four experiments were performed and the physiological parameters (filtration, oxygen uptake, nitrogen excretion) were measured on control and treated animals.

No significant differences in physiological responses (filtration, oxygen uptake, nitrogen excretion) of treated Mytilus galloprovincialis was observed as compared to controls when test species was exposed to 132 mg/kg dry weight LAS. It shows the absence of a toxic action of LAS contaminated sediments.

Endpoint:
sediment toxicity: long-term
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Study period:
Not reported
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Justification for type of information:
Refer to the section 13 of the dataset for details on the read across justification.
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)
Deviations:
yes
Remarks:
For both acute and chronic tests duplicates were used, instead of three replicates for ECx and four replicates for NOEC as recommended by guideline.
Principles of method if other than guideline:
Not applicable
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
Surfactant levels in sediment, OW, and IW were measured during the hatchability and chronic tests.
A detailed description of the analytical procedures is not available in either the publication or the study report.

SEDIMENT
- Sorbed levels of LAS were measured at the beginning and twice during the sediment-spiking experiment. A 3 ml syringe with the narrow end removed was used to collect sediment cores from each chamber.

PORE WATER (INTERSTITIAL WATER) (IW)
- Sampling interval: Upon completion of each test, IW was collected by decanting overlying water, centrifuging the wet sediment at 10,000 rpm for 40 min, and collecting the supernatant as IW.

OVERLYING WATER (OW)
- Sampling interval: Sampled every 2 to 3 d throughout the tests by pipetting duplicate 10 mL aliquots directly from test chambers.
Vehicle:
no
Details on sediment and application:
PREPARATION OF SPIKED SEDIMENT
- Natural stream sediment was collected from a pristine site in Rapid Creek, South Dakota, and contained no detectable levels of LAS, pesticides, or heavy metals as determined by GC and AA analyses.
- Pooling or mixing of different substrates: Not applicable
- Method of mixing: Mechanical stirring
- Details of spiking: Test material was added to sediment slurry and mechanically stirred overnight. Then the sediment was poured into each test chamber and allowed to settle.
- Equilibration time: overnight, with mechanical mixing
- Equilibration conditions: Not reported
- Controls: Control was maintained from the sediment without the addition of test material

PREPARATION OF SPIKED WATER
- Details of spiking: The test materials were combined in known proportions in aqueous stock solutions.
- Controls: Dilution water without test materials.
Test organisms (species):
Chironomus riparius
Details on test organisms:
TEST ORGANISM
- Common name: Midge
- Strain/clone: Not reported
- Source: from P&G ESD (environmental safety department) stock. Original source not provided.
- Age of parental stock: Not reported
- Breeding conditions: Midges used in this study were reared in 10-gallon tanks, with screened tops, containing 4 gallons of aerated well water replenished at a rate of 2 L/hr. Two inches of natural stream sediment served as substrate in culture chambers. Midge cultures (and test organisms) were fed a mixed diet of Ralston-Purina trout chow-dehydrated alfalfa (5:1, w/w). This was supplemented with commercial dog treats at a rate adjusted to prevent fouling. Cultures were maintained at 22 + 2 degrees C. Water hardness was 150 mg/L as CaCO3, pH ranged 7.8 to 8.4, and there was a 16:8 hr photoperiod (400 ft-c).
- Handling of egg masses and larvae: Not reported
- Age of animals at beginning of exposure: 1-2 d
- Feeding during test: Yes
- Food type: Same as culture. Feeding was discontinued upon emergence of the first adult in each test chamber.
- Amount: Not reported
- Frequency: Not reported

ACCLIMATION
- Acclimation period: Not reported. However, midges were obtained in-house, cultured under the same conditions as the test.
- Acclimation conditions: Same
- Type and amount of food: See description of culture above.
- Feeding frequency: Not reported
- Health during acclimation (any mortality observed): Not reported
Study type:
laboratory study
Test type:
other: Semistatic (Egg hatchability) & Flow through (Chronic assay)
Water media type:
freshwater
Type of sediment:
natural sediment
Limit test:
no
Duration:
24 d
Exposure phase:
total exposure duration
Remarks:
72 h (Egg hatchability) was also done
Post exposure observation period:
Not reported
Hardness:
150 mg/L as CaCO3
Test temperature:
22±2°C
pH:
7.8-8.4
Dissolved oxygen:
Details not provided in publication. However, the chronic test was flow-through, and the acute test was static renewal, and low DO was not anticipated.
Salinity:
Not reported
Ammonia:
Not reported
Nominal and measured concentrations:
Egg hatchability (acute tes): Nominal concentrations not provided in publication. Measured concentrations were 0.0, 1.0, 4.7, 9.4, and 18.9 mg/L.

Chronic assay (test a): Nominal concentrations not provided in publication. The measured concentrations provided in the report were 0, 2.4, and 3.7 mg/L.

Chronic assay (test b): Nominal concentrations were 0, 1.5, 3, 6, and 12 mg/L. Measured concentrations not available for test b.

Chronic assay (sediment-spike LAS): Nominal concentrations not provided in publication. Measured concentrations were 0.0, 8±2, 42±5, 146±18, 319±23, 993±225 mg/kg sediment (dry weight).

All results are based on measured concentrations, except for test b. Details on measured concentrations are in "any other information on results" below (Tables 1,2,3,4).
Details on test conditions:
TEST SYSTEM- Test container (material, size): 13 W x 25 L x 18 H cm dimensions chamber (chronic assay); 50 ml Cylindrical test chamber with Nitex® bottom ( Egg hatchability);
- Sediment volume: 350 g (note: chronic tests were conducted with and without sediment)
- Weight of wet sediment with and without pore water: 350 g sediment (dry weight equivalent) per test chamber (Chronic assay); Wet sediment was autoclaved for 40 to 60 min before testing to reduce microbial populations and minimize initial rates of surfactant biodegradation.
- Overlying water volume: Not reported
- Depth of sediment and overlying water: Not reported
- Aeration: No (chronic test was flow-through; acute test was semi-static)

EXPOSURE REGIME (Egg hatchability)
- No. of organisms per container (treatment): 20 eggs in a loop
- No. of replicates per treatment group: Duplicate
- No. of replicates per control / vehicle control: Duplicate
- Feeding regime: Fed each day following water replenishment
- Type and preparation of food: Not reported
- Amount of food: Not reported

EXPOSURE REGIME (Chronic assay)
- No. of organisms per container (treatment): 2 0 larvae per chamber
- No. of replicates per treatment group: Duplicate
- No. of replicates per control / vehicle control: Duplicate
- Feeding regime: Each food formulation daily
- Type and preparation of food: Not reported
- Amount of food: 1 mL

RENEWAL OF OVERLYING WATER
- Details on volume additions: Egg hatchability test: Replenished daily by trickling 150 mL directly into each test chamber and allowing excess volume from the overflow beaker to drain. Chronic test: flow-through design; details on renewal not provided.
- Flow-rate: Not reported

OVERLYING WATER CHARACTERISTCS: Not reported
- Type of water: Blend of deionized, reverse osmosis water and well water with a hardness of approximately 150 mg/L as CaCO3. This “blended” water, a mixture of deionized and well water, is often used in environmental testing at P&G. The details are not provided in the publication, but this water has been well characterized.
- Filtration: Not reported
- Alkalinity: Not reported
- Conductivity: Not reported
- Particulate matter: Not reported
- Total organic carbon: Not reported
- Chemical oxygen demand: Not reported
- Unionized ammonia: Not reported
- Residual chlorine: Not reported
- Total organic chlorine compounds and PCBs: Not reported
- Total organophosphorous compounds: Not reported
- Total organic chlorine: Not reported

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Pristine site in Rapid Creek, South Dakota
- Contamination history of site: Contained no detectable levels of test materials, pesticides or heavy metals

HANDLING OF NATURAL SEDIMENT
- Time of collection: Not reported
- Core depth: Not reported
- Water depth: Not reported
- Storage conditions: Not reported
- Storage duration (prior to test): Not reported

CHARACTERIZATION OF SEDIMENT
- Particle size distribution:
% fine sand: 6 %
%medium sand: 4%
% fine silt : 19 %
% clay: 71 %
- Colour/texture: Not reported
- Moisture: Not reported
- Presence of macrophytes/animals: Not reported
- Metals: Not reported
- Sulfides: Not reported
- Organic compounds: Not reported
- Total volatile solids: Not reported
- Acid volatile sulfides: Not reported
- Oil and grease: Not reported
- Petroleum hydrocarbons: Not reported
- Sediment sieved: Not reported
- pH pore water: Not reported
- pH dry matter and/or whole sediment: Not reported
- Ammonia content of pore water: Not reported
- Total organic carbon (%): 4.2% prior to testing; 8.8% reanalysis following the test
- Total inorganic carbon (%): Not reported
- BOD: Not reported
- COD: Not reported
- CEC: Not reported
- Proof of absence of chemical contaminants: Yes

OTHER TEST CONDITIONS
- Light quality: Not reported
- Photoperiod: 16 h light : 8 h dark
- Light intensity: 400 ft-c at the water surface

EFFECT PARAMETERS MEASURED: Acute test - egg hatching and survival of newly hatched larvae. Chronic test - midge larval and pupal development was measured by % emergence as winged adults (daily observations).

TEST CONCENTRATIONS
- Spacing factor for test concentrations: Egg hatchability test: 2.0 to 4.7. Chronic test: 2.2 to 5.3. These spacing factors are based on the measured concentrations.
- Range finding study: Static acute (48 hr) tests with 72-hr, posthatch larvae were used to target concentration ranges for the initial chronic test with nonspiked sediment. (No details of the range finding study are provided in the publication.)
- Results used to determine the conditions for the definitive study: Yes

CHRONIC ASSAY PROCEDURE
-Test materials were cycled through the chambers for at least 3 d to equilibrate exposure conditions before introducing organisms.
- Water flow was turned off for 24 h to allow larvae to settle to the bottom. Before continuous cycling was restarted, overflow water from a single cycle was collected from each chamber and examined for larvae. If larvae were present, water flow was suspended an additional 24 h. In most cases, the larvae settled during the initial static period. Tests were continued until all live midges emerged as adults.
- The average test duration was 24 d. Numbers of winged adults were recorded daily; typically, they first emerged 12 to 14 d after hatching.
Reference substance (positive control):
no
Key result
Duration:
24 d
Dose descriptor:
NOEC
Effect conc.:
2.4 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr.
Basis for effect:
emergence rate
Remarks on result:
other: test A (no sediment present; exposures to the aqueous fractions of the test substance)
Key result
Duration:
24 d
Dose descriptor:
NOEC
Effect conc.:
4.5 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr.
Basis for effect:
emergence rate
Remarks on result:
other: test A (with sediment). Estimated from graph.
Key result
Duration:
24 d
Dose descriptor:
NOEC
Effect conc.:
3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
emergence rate
Remarks on result:
other: test B (no sediment present; effects of substrate type)
Key result
Duration:
24 d
Dose descriptor:
NOEC
Effect conc.:
3 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
emergence rate
Remarks on result:
other: test B (with sand-silt substrate; effects of substrate type)
Key result
Duration:
24 d
Dose descriptor:
NOEC
Effect conc.:
6 mg/L
Nominal / measured:
nominal
Conc. based on:
act. ingr.
Basis for effect:
emergence rate
Remarks on result:
other: test B (with sand and silt substrates; effects of substrate type)
Key result
Duration:
24 d
Dose descriptor:
NOEC
Effect conc.:
319 mg/kg sediment dw
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr.
Basis for effect:
emergence rate
Remarks on result:
other: sediment spiked with LAS
Duration:
24 d
Dose descriptor:
LOEC
Effect conc.:
993 mg/kg sediment dw
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr.
Basis for effect:
emergence rate
Remarks on result:
other: Sediment spiked with LAS
Duration:
72 h
Dose descriptor:
LC50
Effect conc.:
> 1 - < 4.7 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr.
Basis for effect:
mortality
Remarks on result:
other: survival of newly hatched larvae
Details on results:
- Mortality of test animals at end of exposure period: In the egg hatchability assay, at the lowest exposure level 1.5 % mortality was observed. At 4.7 mg/L and above, 100% mortality was observed. For details see Table 1 under ‘Any other information on results incl. tables’
- Total mass of test animals at beginning of test: Not reported
- Changes in body weights of live adults: Not reported
- No. of offspring produced: Not reported
- No. of emerged male and female midges (per vessel and per day): Not reported
- No. of pupae failing to emerge (per vessel and per day): Not reported
- Percent emergence per test concentration: See Tables 2,3,4 under ‘Any other information on results incl. tables’
- Mean development rate of fully emerged midges: Not reported
- Mean individual dry weight of larvae: Not reported
- Morphological abnormalities: Not reported
- Behavioural abnormalities: Not reported
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
Chi-square analyses used for significant differences among treatments and variance homogeneity were applied to numbers of larvae and unhatched egg - Probit analysis used to calculate EC50 values for each data set in chronic assay

Table 1. Effects of LAS upon Chironomus egg hatching success and survival of newly hatched larvae

Average measured concentration

(mg/L)

Egg hatching success

(%)

Survival

(%)

0.0

100

91

1.0

100

88.5

4.7

100

0a

9.4

100

0a

18.9

100

0a

a Significantly  different from control value (p < 0.05)

72 hr (acute) test.

Table 2. Chronic toxicity of LAS to Chironomus: Effect of sediment

Details of this experiment are in a graph in the publication.

Table 3. Chronic toxicity of LAS to Chironomus: Effect of substrate

Overlying water concentration (mg/L; nominal)

Emergence of winged adults (%)

No substrate

Sand

Sand-silt

Silt

0

80

100

100

100

1.5

80

100

100

85

3

75

95

100

85

6

40a

95

75a

75

12

5a

0a

20a

0a

a Significantly different(p< 0.05) from respective control value

Table 4. Partitioning and chronic effects of LAS to Chironomus: Sediment-spiked experiment

Surfactant sediment

Concentrations (ppm; mean ± SE)

Interstitial water (lW)

overlying water (OW)

% Emergence

993±225

15.2 ± 2.7

1.69±0.12

73a

319 ± 23

15.0 ± 1.4

1.05 ± 0.Q7

90

146 ± 18

7.7±1.1

0.59 ± 0.05

90

42 ± 5

1.5 ± 0.3

0.35 ± 0.01

90

8 ± 2

0.2 ± 0.0

0.32 ± 0.01

95

0(control)

0

0

98

a Significantly different(p< 0.05) from control value

 

Validity criteria fulfilled:
yes
Conclusions:
The effect of linear alkylbenzene sulfonate on midge was evaluated in acute and chronic tests. The 24-day chronic NOEC was 2.4 mg/L, based on emergence. The 72-hour acute LC50 was between 1.0 and 4.7 mg a.i./L, based on survival of newly hatched larvae.
Executive summary:

A sediment toxicity test of LAS (linear alkylbenzene sulfonate) was conducted following the OECD 218 guideline, using the midge Chironomus riparius.  All results are based on the measured concentration of the test substance. The LAS had an average alkyl chainlength of 11.9, and was comprised of C10 -C14 alkyl chains.

In an egg hatchability semi-static assay (acute test), midge eggs were exposed to a range of LAS concentrations in water and were monitored for hatching success and posthatch survival. No significant reduction in egg hatching was observed at the highest concentration tested (18.9 mg/L). However, significant reduction in the survival of the newly hatched larvae occurred at 4.7 mg/L. The 72h LC50 was between 1.0 and 4.7 mg/L, based on survival of newly hatched larvae.

In the partial life cycle bioassay in a flow-through sediment/water test system (chronic test), percentages of winged adults emerging after continuous exposure of larvae and pupae to a range of LAS concentrations were determined. Exposure concentrations in sediment, interstitial water and overlying water were monitored by 14C liquid scintillation counting. The effect of LAS level in the water column was determined in a total of 6 chronic toxicity tests. The NOECs from these tests were 2.4 -3.0 (without sediment), and 3.0 -6.0 (with sediment). The effect of LAS on Chironomus was also evaluated in an experiment using sediment spiked with LAS. In this test, the NOEC of sediment-spiked LAS was 319 mg/kg sediment (dry weight basis).

Description of key information

MEA-LAS dissociates into MEA and LAS in water. The acute toxicity of LAS to several species of sediment organisms has been studied.

Study 1 (C10-13 LAS):

The toxicity of C10-13 LAS, sodium salt (average alkyl chain length C11.4) to freshwater benthic organisms (Lumbriculus variegatus) was assessed during exposure to spiked sediment. Samples of natural sediment were spiked at concentrations of 50, 75, 100, 150, 300 and 600 mg/kg sediment dw. Test organisms (n=10) were exposed to test substance for 28 d. At the end of study, the organisms were observed for survival and biomass. The test substance half-life in aerobic sediment was approximately 20 d. In a long-term toxicity study, the 28 d NOEC for Lumbriculus variegatus for survival and reproduction was 81 mg/kg sediment dw, based on the mean of Day 0 and Day 28 concentrations, with EC10 and EC50 values of 73 and 105 mg/kg sediment dw, respectively. The NOEC for biomass was 82 mg/kg sediment dw, based on the mean of Day 0 and Day 28 concentrations, with EC10 and EC50 values of 98 and 109 mg/kg sediment dw, respectively (Comber, 2006).

Study 2 (C10-13 LAS):

The toxicity of C10-13 LAS, sodium salt (average alkyl chain length C11.4) to the nematode Caenorhabditis elegans was assessed during exposure to spiked sediment. Samples of natural sediment were spiked with concentrations of 0, 10, 50, 100, 200, 300, 400, 500, 750 and 1000 mg/kg sediment dw.  Test organisms (n=10) were exposed to test substance for 3 d. The organisms were then observed for growth and reproduction during the exposure period. The EC10 value was 275 mg/kg sediment dw based on growth rate. The NOECs were 200, 200 and 100 mg/kg sediment dw, based on growth, fertility and egg production, respectively (Comber, 2006).

Study 3 (C10-13 LAS):

The aim of this study was to evaluate the effects of sediment-sorbed C10-13 LAS, sodium salt (likely average alkyl chain length C11.6) on the marine mussel, Mytilus galloprovincialis. Test species (n=30), divided into groups of 10, were exposed to the sediments spiked with 132 mg/kg sediment dry weight (dw) of LAS mixtures for 7 d. Four experiments were performed and the physiological parameters (filtration, oxygen uptake, nitrogen excretion) were measured on control and treated animals. No significant differences in physiological responses (filtration, oxygen uptake, nitrogen excretion) of treated mussels were observed as compared to controls, showing the absence of a toxic action of LAS contaminated sediments (Marin, 1994).

Study 4 (C10-14 LAS):

A sediment toxicity test with C10-14 LAS, sodium salt (average chain length C11.9) was conducted according to OECD Guideline 218 using the midge Chironomus riparius.  All results were based on measured concentrations of the test substance. In an egg hatchability semi-static assay (acute test), midge eggs were exposed to a range of concentrations in water and were monitored for hatching success and post hatch survival. No significant reduction in egg hatching was observed at the highest concentration tested (18.9 mg/L). However, significant reduction in the survival of the newly hatched larvae occurred at 4.7 mg/L. The 72 h LC50 was between 1.0 and 4.7 mg/L, based on survival of newly hatched larvae. In the partial life cycle bioassay in a flow-through sediment/water test system (chronic test), percentages of winged adults emerging after continuous exposure of larvae and pupae to a range of LAS concentrations were determined. Exposure concentrations in sediment, interstitial water and overlying water were monitored by 14C liquid scintillation counting. The effect of LAS level in the water column was determined in a total of 6 chronic toxicity tests. The NOECs from these tests were 2.4 - 3.0 (without sediment) and 3.0 - 6.0 (with sediment) mg/L. The effect of LAS on Chironomus was also evaluated in an experiment using spiked sediment. In this test, the NOEC was 319 mg/kg sedimentdry weight (Pittinger, 1986 and 1989).

Key value for chemical safety assessment

EC50 or LC50 for freshwater sediment:
105 mg/kg sediment dw
EC10, LC10 or NOEC for freshwater sediment:
81 mg/kg sediment dw

Additional information