Ashes (residues), cenospheres

Sediment toxicity

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Reason / purpose for cross-reference:

reference to same study

Principles of method if other than guideline:

- Principle of test: The purpose of the study was to investigate the bioaccumulation in three different mussel species during and after dredging activities in situ in the ash affected sites from the Tennessee Valley Authority Kingston Fossil Plant coal ash spill. Health condition through the mussel condition index was also analyzed.
- Short description of test conditions: Mussels were caged for 1 year in ash affected and unaffected river sites for both the dredging period and the post-dredging period. Additionally mussels of each species were kept under laboratory conditions as a reference.
- Parameters analysed / observed: Mussel health (mussel condition index) and concentrations of As, Cd, Cr, Pb, Ni, Se, Hg, U, Fe, Mg, Al, Sb, Ba, Be, Co, Cu, Mn, Mo, Ag, Sr, Tl, V, and Zn in soft tissues were analyzed. Potential differences based on location, dredging activities and species were investigated.

GLP compliance:

no

Remarks:

peer reviewed data - GLP not relevant

Analytical monitoring:

yes

Details on sampling:

- Sampling intervals/frequency for test organisms: During dredging activities mussels were placed in Emory River at 20th of June 2009 and sampled at 14th of June 2010, in lower Clinch River at 21st of October 2009 and sampled at 31 August 2010. During post dredging activities all mussels were placed at 28th of October 2010 in the rivers and sampled at 3rd of October 2011. Laboratory reference mussels were introduced at 5th of May 2009 and sampled at between July and August of 2010.
- Sample storage conditions before analysis: Tissue was frozen and held at −20 °C until laboratory analysis.
- Details on sampling and analysis of test organisms and test media samples : 75 individuals of each species were collected from the Tennessee River and transported to the Cumberland River Aquatic Center (Gallatin, TN) in aerated coolers (<3 °C). Prior to mussel deployment back in river, mussels were acclimatized in the laboratory and each individual was thoroughly scrubbed, weighed, and affixed with a number. At end of river exposure period mussels were held between 36 and 48 h to ensure purging of gut contents before processing. Mussels were additionally scrubbed before processing. Then mussels were weighed (total and tissue separately). Foot, mantle and gill were removed and remaining tissue was homogenized, dried (106 °C), digested and analyzed for metals. Health condition index was calculated as follows: condition index = tissue wet weight / shell volume.

Vehicle:

no

Test organisms (species):

other: Ligumia recta, Elliptio crassidens, Cyclonaias tuberculata

Details on test organisms:

TEST ORGANISM
- Common name: black sandshell, elephant ear, purple wartyback
- Source: Emory and Clinch Rivers

ACCLIMATION
- Acclimation period: Prior to initiation of field study, organisms were kept for 45 days in the laboratory.
- Acclimation conditions: First submerged in ∼35 cm of water for 45 d then deployed in flow-through raceways (flow rate of 454 L/min). Water source was from the Cumberland River.
- Type and amount of food: Not fed during holding in laboratory.

Study type:

semi-field study

Test type:

other: monitoring data

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

1 yr

Exposure phase:

total exposure duration

Remarks:

Mussels were caged for 1 year in ash affected and unaffected river sites for both the dredging period and the post-dredging period. Additionally mussels of each species were kept under laboratory conditions as a reference.

Nominal and measured concentrations:

River sites studied had different ash contents.

Details on test conditions:

TEST SYSTEM
- Collected and acclimatized mussels were deployed at four sites in the vicinity of the ash spill. During dredging activities mussels were deployed at following locations: Emory River - directly downstream the spill, Emory River - upstream the spill, lower Clinch River - downstream the Emory River cofluence. After the dredging period mussels were placed at following four locations: Emory River - directly downstream the spill, lower Clinch River - downstream the Emory River cofluence, Clinch River - upstream of the Emory River confluence, Tennessee River - downstream of the Clinch River confluence. Additionally, 10 reference mussels of each species were kept in the laboratory in concrete raceways under the same conditions described under "details on test organisms" for the 45-day holding period.
- Test vessel: Custom deployment enclosures constructed of 5-cm PVC pipe in a 1.2×1.2 m square frame design with 2.5 cm squared high-density polyethylene (HDPE) plastic mesh covering the interior of the frame. Anchor supports (1 m long; made of 5-cm PVC) with custom pointed ends (for attachment into the river bottom) were attached to each corner of the frame.


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Water source for organisms in laboratory was from the Cumberland River.


EFFECT PARAMETERS MEASURED
- mussel condition index values and As, Cd, Cr, Pb, Ni, Se, Hg, U, Fe, Mg, Al, Sb, Ba, Be, Co, Cu,Mn, Mo, Ag, Sr, Tl, V, and Zn concentrations in soft tissue were determined.

Reference substance (positive control):

no

Remarks on result:

other: For results see "any other information on results incl. tables" and "overall remarks, attachments"

Reported statistics and error estimates:

ANOVAs with Tukey’s post hoc tests: for analyses of metal concentrations and condition index for each species between site and lab reference samples.
JMP Pro 9 software (Cary, NC) was used for calculations.

Emory River sites: increase of condition index values were observed for the post dredging period for all three species while condition index values were decreased during dredging period.

Lower Clinch: no differences in condition index was recorded.

All control samples from the laboratory showed significantly lower condition indexes for two species (black sandshell and purple wartback) at both periods. This could be related to different water parameter from their natural environment.

Otherwise condition index measurements showed relatively constant values.

Reference 2

Endpoint:

sediment toxicity: short-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

other: ASTM International - Standard test method for measuring the toxicity of sediment‐associated contaminants with freshwater invertebrates

Version / remarks:

2013

Qualifier:

according to guideline

Guideline:

other: US Environmental Protection Agency - Methods for measuring the toxicity and bioaccumulation of sediment associated contaminants with freshwater invertebrates.

Version / remarks:

2000

Deviations:

yes

Remarks:

For H. azteca modified for exposure duration (28 d) and age of test organisms (2–7 d) at test initiation.

Principles of method if other than guideline:

- Principle of test: Sediment toxicity test after a coal ash spill from Tennessee Valley Authority Kingston Fossil Plant. A tiered approach was used in this study. In this robust study summary the short-term experimental result is presented.
- Short description of test conditions: Sediment samples through a gradient of ash content in the Emory and Clinch rivers were collected for tiered toxicity testing (10 d acute toxicity test and long term partial life cycle toxicity test) with Hyalella azteca and Chironomus dilutus.
- Parameters analysed / observed: Test endpoints for short term test were survival, growth (ash‐free dry weight for C. dilutus, dry weight for H. azteca), and biomass.

GLP compliance:

no

Remarks:

peer reviewed data - GLP not relevant

Analytical monitoring:

yes

Details on sampling:

SEDIMENT
- Source: Emory and Clinch River
- Concentrations: Both the Emory and Clinch Rivers offer sediment ash content ranging from 1% up to 90% of sediment for setting up dose-response experiments.
- Sampling depth: upper 6 inches of sediment
- Sampling interval: Winter and spring 2011 from 8 ash affected and 2 reference locations per river (10 sampling locations in total per river).
- Preliminary work: In preliminary work, more than 260 sediment samples were collected from the Emory, Clinch, and Tennessee Rivers to provide a general description of the distribution of ash depths and percent ash within the river system, and over 80 were chemically analyzed for metals and particle‐size distribution. Results were used to select locations for sediment toxicity testing that captured the range of ash concentrations and sediment types observed in the Emory and Clinch Rivers.

PORE WATER
- Sampling: Porewater collected from same locations as sediment. Porewater was extracted by centrifugation and then filtered, preserved, and analyzed for dissolved metals, chemical speciation of As and Se, major ions, hardness, and dissolved and dissolved organic carbon.

OVERLYING WATER
- Sampling: Collected from approx. 0.5 m above the stream bed at an upstream reference area. Water was collected for testing and metal analysis.

Vehicle:

no

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Source of sediment: collected from Emory and Chlinch Rivers
- Details of spiking: Both the Emory and Clinch Rivers offer sediment ash content ranging from 1% up to 90% for setting up dose-response experiments.
- Controls: see "details on test conditions"

Test organisms (species):

other: Hyalella azteca and Chironomus dilutus

Details on test organisms:

TEST ORGANISM
- Age of animals at beginning of exposure: 2nd and 3rd instar C. dilutus larvae and 12 to 13 day old H. azteca larvae.

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

10 d

Exposure phase:

total exposure duration

Nominal and measured concentrations:

9 locations per river - with different ash concentrations (gradient) - 18 concentrations in total
The ash content of the Clinch River samples ranged from 20% to 41% and of the Emory River between 1% and 88%, allowing to perform studies with different ash concentrations for a dose - respond experiment. For sample name and respective concentration see field "any other information on material and methods incl. tables".

Details on test conditions:

EXPOSURE REGIME
- No. of organisms per container (treatment): 10
- No. of replicates per treatment group: 8
- No. of replicates per control: 4 (1. reference sediment from the Boardman River, a stream with nearly 100% forested watershed and dechlorinated municipal tapwater from 2. laboratory water only, 3. laboratory sediment with site water, and 4. site reference sediment with site water.)

OVERLYING WATER CHARACTERISTCS
- Type of water: River water
- Source of water: Overlying water collected from unaffected upstream river locations.

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Emory and Clinch Rivers
- Contamination history of site: Ash contaminated and reference sites.

HANDLING OF NATURAL SEDIMENT
- Time of collection: see "details on sampling"
- Core depth: see "details on sampling"
- Water depth: see "details on sampling"
- Storage conditions: see "details on sampling"

CHARACTERIZATION OF SEDIMENT
- Particle size distribution : Reference sediment in Clinch River was mostly sand and in Emory River both sand and silt. Clinch River sediment downstreams was mostly silt with small amounts of sand and clay while Emory River downstreams sediment samples contained silt and sand with lower amounts of clay and gravel. Emory River sediments showed larger particle sizes compared to Clinch River.
- Organic compounds: Clinch River: 1.4 - 2.5% organic carbon. Emory River: 0.5 - 3.8% organic carbon.


EFFECT PARAMETERS MEASURED:
- survival, growth (ash‐free dry weight for C. dilutus, dry weight for H. azteca), biomass.

Reference substance (positive control):

no

Duration:

10 d

Remarks on result:

other: For results see "any other information on results incl. tables" and "overall remarks, attachments"

Reported statistics and error estimates:

ToxCalcTM (version 5.0.32; Tidepool Scientific Software) was used to identify significant differences relative to the site reference samples.
Principal component analysis (PCA) using Statistical Analysis System software (SAS 2010): used as the first step in evaluating potential relationships between sediment chemistry and toxicity test results.
Pearson correlations (SAS 2010): covariant variables identified by PCA were further evaluated.
Linear regressions: also used to evaluate the sediment chemistry and toxicity test results for outliers and to evaluate the strengths of relationships among variables.

For both organisms the highest adverse effects were observed in the samples with the two highest ash concentration (64% and 88% ash).

More specifically for:

- C. dilutus: 7 sediment samples (reflecting different concentrations) from the Emory River and two from the Clinch River showed significant decrease of the survival or biomass compared to the control.

- H. azteca: 5 sediment concentrations from the Emory River and 1 from the Clinch River showed significant decrease in the biomass. Survival decreased in 4 sediment concentrations in the Emory River. Percent ash, As, and Sr covaried and all 3 were clustered with mortality in the PCA analysis (i.e., when ash, As, and Sr concentrations increase, mortality also increased).

For more details see "overall remarks, attachments".

The PCA results indicate that the magnitude of toxic effects is proportional to the ash, As, and Sr concentrations in sediments.

Constituents in sediment like PCBs, pesticides and PAHs did not correlate with toxicity.

As, Ba, Be, B, Cr, Cu, Se, Sr, and V contents in ash correlated strongly with % ash.

The sediment toxicity tests demonstrated mostly sublethal effects on both Hyalella growth and midge growth and emergence; however, effects were mostly limited to greater than 40% ash exposures, in which As was at or exceeded probable effect concentrations (consensus based sediment quality guidelines (SQGs) proposed by MacDonald et al., 2000).

In conclusion ash and ash related constituents adversely affected individual laboratory organisms but at very high exposure concentrations (>40%) of ash.

Reference:

MacDonald DD, Ingersoll CG, Berger TA. 2000. Development and evaluation of consensus‐based sediment quality guidelines for freshwater ecosystems. Arch Environ Contam Toxicol 39:20–31.

Reference 3

Endpoint:

sediment toxicity: long-term

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: US Environmental Protection Agency - Methods for measuring the toxicity and bioaccumulation of sediment associated contaminants with freshwater invertebrates.

Version / remarks:

2000

Deviations:

yes

Remarks:

H. azteca: modified for exposure duration (28 d) and age of test organisms (2–7 d) at test initiation. C. dilutus: modified for exposure duration and age (<24 h) of test organisms (C. dilutus) at test initiation.

Principles of method if other than guideline:

- Principle of test: Sediment toxicity test after a coal ash spill from Tennessee Valley Authority Kingston Fossil Plant. A tiered approach was used in this study. In this robust study summary the long term (partial life cycle) experimental result is presented.
- Short description of test conditions: Sediment samples through a gradient of ash content in the Emory and Clinch rivers were collected for tiered toxicity testing (10 d acute toxicity test and long term partial life cycle toxicity test) with Hyalella azteca and Chironomus dilutus.
- Parameters analysed / observed: Survival and growth were recorded at test end. NOEC, LOEC and IC25 (the 25% impairment concentration) were calculated for survival, growth, and biomass.

GLP compliance:

no

Remarks:

peer reviewed data - GLP not relevant

Analytical monitoring:

yes

Details on sampling:

- After 20 d, 4 replicates from each test dilution were sacrificed for measurements of survival, growth, and biomass. At test end (no emergence of adults over a 72 h period for each control replicate), partial life cycle survival and emergence were observed for the remaining replicates.

Vehicle:

no

Details on sediment and application:

PREPARATION OF SPIKED SEDIMENT
- Source of sediment: collected from Emory and Chlinch Rivers
- Details of spiking: Both the Emory and Clinch Rivers offer sediment ash content ranging from 1% up to 90% for setting up dose-response experiments.

Test organisms (species):

other: Hyalella azteca and Chironomus dilutus

Details on test organisms:

TEST ORGANISM
- Age of animals at beginning of exposure: Hyalella azteca: 2-7 d; Chironomus dilutus: < 24 h

Study type:

laboratory study

Test type:

static

Water media type:

freshwater

Type of sediment:

natural sediment

Limit test:

no

Duration:

28 d

Exposure phase:

other: partial life cycle

Nominal and measured concentrations:

10 different ash concentrations in % (4 original samples and 6 dilutions 0, 20, 40, 60, 80, 100% dilution).

Details on test conditions:

EXPOSURE REGIME
- No. of organisms per container (treatment): H. azteca: 10, C. dilutus: 12
- No. of replicates per treatment group: H. azteca: 8, C. dilutus: 12

OVERLYING WATER CHARACTERISTCS
- Type of water: River water
- Source of water: Overlying water collected from unaffected upstream river locations.

SOURCE OF NATURAL SEDIMENT
- Location and description of sampling site: Emory and Clinch Rivers
- Contamination history of site: Ash contaminated and reference sites.

CHARACTERIZATION OF SEDIMENT
- Particle size distribution: Reference sediment in Clinch River was mostly sand and in Emory River both sand and silt. Clinch River sediment downstreams was mostly silt with small amounts of sand and clay while Emory River downstreams sediment samples contained silt and sand with lower amounts of clay and gravel. Emory River sediments beared larger particle sizes compared to Clinch River.
- Organic compounds: Clinch River: 1.4 - 2.5% organic carbon. Emory River: 0.5 - 3.8% organic carbon.

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- At 20 d, 4 replicates from each test dilution were sacrificed for measurements of survival, growth, and biomass.
- At test end (no emergence of adults over a 72 h period for each control replicate), partial life cycle survival and emergence were recorded for the remaining replicates. NOEC, LOEC and IC25 values were determined (however not reported in publication).

TEST CONCENTRATIONS
- Range finding study : yes
- Results used to determine the conditions for the definitive study: Tiered test - experimental design of this study is based on short term study (see reference study). Acute test results were used to identify 4 high priority investigative locations per river for further evaluation in the longer‐term, definitive tests. Gaps in the ash concentration distribution resulting from the small number of samples were filled in by the dilution series in the longer‐term tests.

Reference substance (positive control):

no

Duration:

28 d

Remarks on result:

other: For results see "any other information on results incl. tables" and "overall remarks, attachments"

Reported statistics and error estimates:

ToxCalcTM (version 5.0.32; Tidepool Scientific Software) was used to identify significant differences relative to the site reference samples.
Principal component analysis (PCA) using Statistical Analysis System software (SAS 2010): used as the first step in evaluating potential relationships between sediment chemistry and toxicity test results.
Pearson correlations (SAS 2010): covariant variables identified by PCA were further evaluated (e.g. relationships between sediment chemistry, ash content and toxicity)
Linear regressions: also used to evaluate the sediment chemistry and toxicity test results for outliers and to evaluate the strengths of relationships among variables.

C. dilutus: all 4 Emory River sediment samples showed significant decrease of emergence and survival. In the Clinch River only one sample showed significant effects.

H. azteca: 6 out of 8 sediment samples showed a significant reduction of the biomass or survival. All 4 Emory River sediments showed effects while 2 sediments from the Clinch River exhibited effects.

The PCA results indicate that the magnitude of toxic effects is proportional to the ash, As, and Sr concentrations in sediments.

Constituents in ash like PCBs, pesticides and PAHs did not correlate with toxicity.

As, Ba, Be, B, Cr, Cu, Se, Sr, and V contents in ash correlated strongly with % ash.

Percent ash, As, Se, and Sr were most highly correlated with statistically significant toxic effects and with each other. Cu also appeared to be a likely toxicant at one sediment (CRM1.5), but the analysis identified it as an outlier probably not associated with the residual ash.

For more details on results see "overall remarks, attachments".

Reference 4

Endpoint:

sediment toxicity, other

Remarks:

Short- term and long-term

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Remarks:

Summary of available data used for the endpoint assessment of the target substance.

Adequacy of study:

weight of evidence

Justification for type of information:

Refer to analogue justification provided in IUCLID section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Remarks on result:

other: Based on results from WoE source studies, the potential for toxicity towards sediment organisms is expected to be low.

Description of key information

Toxicity to sediment organisms is considered to be low.

Additional information

Since no studies investigating the sediment toxicity of cenospheres, fly ash (CAS 93924-19-7) are available, in accordance to Regulation (EC) No 1907/2006 Annex XI, 1.5 a read-across to structurally related ashes (CAS 931-322-8) was conducted. This read-across is justified within the analogue justification in IUCLID Section 13.

End of 2008 4.1 million m³coal ash were released into the Emory, Tennessee and Clinch rivers from an accident in the Tennessee Valley Authority (TVA) Kingston Fossil Plant. This unfortunate event provided an opportunity to directly study the impact of coal fly ash in a large lotic system since more than one rivers were affected. A variety of studies were initiated by multiple actors to assess ecological risks to different organisms. Since fly ash contains a diversity of metals such as As, Cr, Cu, Pb, Hg, Ni, Se, Tl, V, Zn, it is of ecological concern. Among others the toxicity of ash and especially its comprised metals towards sediment organisms was investigated.

Stojak et al. (2014) applied a tiered approach to evaluate short and long term effects to Hyalella azteca and Chironomus dilutes. Sediment samples were collected within the river system that encompassed a spatial gradient of ranging ash content and analyzed. The ash content of the Clinch River sediment samples ranged from 20% to 41% and of the Emory River from 1% and 88%, allowing to perform studies with different ash concentrations for a dose - respond experiment. The short-term toxicity test was conducted according to the EPA methods 100.1 and 100.2, for H. azteca and C. dilutes, respectively (USEPA 2000, whole‐sediment acute tests). C. dilutus and H. azteca larvae were exposed to undiluted site sediment with site water as well as 4 different kind of controls for 10 days. The test parameters analysed were survival, growth and biomass.

The long-term partial life study was designed based on the results of the short-term study. 4 high priority sites per river were chosen for further testing. 10 different ash concentrations were tested (4 original samples and a dilution series in which the selected sediment was diluted with their reference sediment at a volume-based ratio of 10 20, 40, 60, 80 and 100%). The two test organsms were exposed to the ash-sediment concentrations for 28 d. Survival and growth were recorded at the test end.

Statistical analysis of the results demonstrated that percent ash, As, Se, and Sr were most highly correlated with statistically significant toxic effects and with each other. As and Se were found to be the most likely toxic constituents. Effects to sediment organisms were however low and mostly attributed to sediments with an ash content of greater than 40%, in which As was significantly elevated and exceeding recommended probable effect concentrations. Furthermore, the statistical analysis results showed that toxicity observed did not correlate with residues other than ashes, like PCBs, pesticides or PAHs that were detected in the sediments studied, therefore the statistic and discussion of this paper focused on the ash associated metals and physical properties of sediment. It was however not clear if effects were caused due to mixture toxicity or due to toxicity by specific compounds.

A further study on the same site is available that investigated concentrations of ash-related metals and compared to potential effects or contaminant advisory levels. The focus of following study was the bioaccumulation of metals in mussels but health condition of the organisms was additionally studied.

The first available publication intended to in situ investigate the bioaccumulation in three different mussel species (black sandshell, elephant ear, purple wartyback) during and after dredging activities in the ash affected sites (Otter et al. 2015). Mussels were caged for 1 year in ash affected and unaffected river sites for both in the dredging period and the post-dredging period. Additionally mussels of each species were kept under laboratory conditions as a control. Mussel health (mussel condition index) and concentrations of 23 metals in soft tissues were analyzed. Potential differences based on location, dredging activities and species were recorded. Metal mussel concentrations were compared with contaminant advisory levels given mainly by the Food and Drug Administration in order to identify potential threats. Results revealed that from all metals measured, only mean lead concentrations were observed in two cases exceeding the respective contaminant advisory level of 1.7 mg/kg given by the Food and Drug Administration. This was observed in the post-dredging period in purple wartyback, (3.2 mg/kg, at Lower Clinch) and in elephant ear (1.9 mg/kg, at Upper Clinch). Dredging activities seemed to have effects on mussel health. At post dredging period however the condition indexes remained constant giving evidence that dredging conditions might be an extreme situation. Therefore these results give further evidence of a low hazard potential caused by the ash spill to sediment organisms (here mussels) even at areas with high ash concentrations.

In conclusion, evidence from long and short-term studies show a low potential of toxic hazard of ashes, including cenospheres, to sediment organisms. The study conducted by Stojak et al. indicated a concern in case of elevated As and Se through ash contamination. However, toxic effects were found only when ash concentrations were over 40% in sediment. The field study by Otter et al. (2015) showed, a negative impact on mussel health only during the exceptional conditions of dredging activities while the condition indexes were constant or increased at post dredging period. Based on these studies the toxicity of ash, including cemospheres, to sediment organisms is considered low.