Ashes (residues), cenospheres

Bioaccumulation: terrestrial

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation: terrestrial

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

Justification for type of information:

Refer to analogue justification provided in IUCLID section 13

Qualifier:

according to guideline

Guideline:

other: US Environmental Protection Agency [USEPA] method 6020

Version / remarks:

Method was used for metal analysis.

Qualifier:

according to guideline

Guideline:

other: USEPA method 1631 and method 1630

Version / remarks:

Method was used to analyze mercury and methylmercury.

Principles of method if other than guideline:

- Principle of test: The purpose of the study was to investigate site-specific bioaccumulation of ash-related metals in tetragnathid spiders in an ash spill affected site and the potential transfer from the aquatic to the terrestrial system.
- Short description of test conditions: Spiders and sediment were collected from ash affected and reference site and were analyzed for metal concentrations.
- Parameters analysed / observed: Concentrations of metals in tetragnathid spiders and sediments were analyzed from ash affected and reference sites. It was investigated whether tetragnathid spider accumulation of metals was site specific and related to metal concentrations in sediments.

GLP compliance:

no

Remarks:

peer reviewed data - GLP not relevant

Radiolabelling:

no

Details on sampling:

- Sampling intervals/frequency for test organisms: Sampling of spiders took place in July 2012 (ERM: 130 spiders; ERM 3: 173 spiders; ERM6: 129 spiders; LERM2: 128 spiders).
- Sampling intervals/frequency for sediment: Sampling of sediments was conducted between 23.05.2011 and 12.12.2012 (3-7 samples from each site).
- Sample storage conditions before analysis: –20 °C
- Details on sampling and analysis of test organisms and test media samples: Spiders were collected from from riparian vegetation at two ash affected and two non ash affected sites by the Emory river. 20-25 individuals from each site were finally analyzed. Animals were weighed and then spider and sediment samples were analyzed for aluminum, lead, molybdenum, nickel, silver, strontium, arsenic, barium, beryllium, cadmium, chromium, cobalt, copper, vanadium, zinc, and selenium (dry wt).

Vehicle:

no

Test organisms (species):

other: Araneae, Tetragnathidae

Details on test organisms:

TEST ORGANISM
- Common name: Tetragnathid spiders
- Source: Spiders were collected from from riparian vegetation at two ash affected (ERM1, ERM3) and two non ash affected (ERM6, LERM2) sites by the Emory river and Little Emory River.

Remarks on result:

other: Concentrations of metals in spiders and in sediments were measured.

Remarks:

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

Reported statistics:

One-way analyses of variance with Tukey’s post hoc tests was used to compare metal concentrations in spiders and sediments.
For analysis JMP Pro 9 software was used.

Findings from metal analysis in spiders:

- Cobalt was significantly higher at ERM1 compared to ERM 6 and LERM 2.

- Selenium was found to be significantly higher at ash affected sites compared to the reference sites. However due to lack of literature data, it is not clear whether these concentrations are of concern.

Findings from metal analysis in sediments:

- Al, Ni, Sr, Ba, Be, Cu, V were higher at ash affected sites compared to reference sites.

- Cr, Co, Se, Zn were higher at ash affected sites compared with at least one reference site.

- Only Se (all sites except ERM6) and Ni (ERM1 site) exceeded USEPA sediment screening thresholds of 2 mg/kg and 22.7 mg/kg respectively. However exceedances are not associated to ash.

Conclusion:

- Although concentrations of metals in sediments were in many cases higher at ash affect sites compared to reference sites, this was not reflected in spiders. Most of metals showed no significant site difference in spiders. This indicates according to the authors a lack of metal bioavailability for this organism. For more details see "Overall results, attachments"

- Selenium however was found to still be bioavailable and accumulated in spiders.

Validity criteria fulfilled:

not applicable

Reference 2

Endpoint:

bioaccumulation: terrestrial

Type of information:

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

Adequacy of study:

weight of evidence

Reason / purpose for cross-reference:

read-across source

Remarks on result:

other: Concentrations of metals in spiders and in sediments were measured.

Remarks:

For results see "any other information on results incl. tables" and "overall remarks, attachments" in source entry. Results from Otter 2013.

Description of key information

Transfer of the ash related metals, including cenospheres, from the aquatic to the terrestrial compartment as studied for tetragnathid spiders is thus considered to be low.

Additional information

Ashes, including cenospheres, are inorganic complex compounds consisting of multitude of unknown and variable constituents (UVCB), and it is therefore technically not possible to determine an overall bioaccumulation for this substance. However, most of metals contained in ashes, which are of concern have been reviewed in literature. 

Since no studies investigating the bioaccumulation 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 a 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 m^3 coal ash were released into the Emory, Tennessee and Clinch rivers due to an accident in the Tennessee Valley Authority (TVA) Kingston Fossil Plant. This unfortunate accidence 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 a long-term ecological concern. Among multiple toxicological and ecotoxicological studies, bioaccumulation potential of metals associated to fly ash was investigated either as an endpoint solely or in combination with toxicological effects.

 

Shortly after the spill, 90% of the ash was removed from the river by dredging. Studies concern both the period of dredging (March 2009 – May 2010) and the post-dredging period after the partial removal of the ash. 5 published studies related to the Kingston spill were taken into account as evidence for the bioaccumulation potential of ash related metals in fish. Publications cover both field monitoring data and laboratory experiments. In some studies special attention was given to specific metals or metalloids, such as Se, As and Hg.

 

One study provides information on the bioaccumulation of ash related metals to terrestrial organisms. Site-specific bioaccumulation of ash-associated metals in tetragnathid spiders in ash spill affected sites and the potential transfer from the aquatic to the terrestrial systems was investigated. Spiders and sediment were collected from ash affected and reference sites and analyzed for metal concentrations. Results showed that although concentrations of metals in sediments were higher at ash affect sites compared to reference sites in many cases, this was not reflected in spiders. Most of metals showed no significant site difference in the tested organisms indicating a lack of metal bioavailability for this organism. Se and Ni were found to be elevated in tetragnathid spiders. However, threshold values are scarce for this organisms and therefore it cannot be concluded that the concentrations could be hazardous. Transfer of the ash related metals from the aquatic to the terrestrial compartment as studied for tetragnathid spiders is based on the results of this study considered to be low.

Available studies for further trophic levels, which are more directly exposed to ashes (fish, sediment organisms) showed in a weight of evidence approach that bioaccumulation of ash associated metals is possible but did not indicate high concerns towards toxicity to any compartment. In only few cases concentrations in organisms exceeded proposed thresholds (e.g. from US EPA, FDA) for the protection of the environment and humans, even under the extreme conditions of the spill. These results are in line with the terrestrial study. Furthermore, it needs to be considered that the spill represents an extreme and worst case situation. Bioavailability and consequently bioaccumulation of ash-related metals is complex and dependent on multiple factors like pH, redox potential, geochemical interactions etc. The site monitoring and lab investigations of the presented publications are highly representative for demonstrating the behavior of ash-associated metals in the water, sediment and soil, with indicating the impact of ash contamination on different fish species and potential of accumulations. However, the pool of these studies do not cover the completely possible spectrum on the bioaccumulation potential of ash related metals under the different environmental conditions.