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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

The bioaccumulation potential of cenospheres is low.

Key value for chemical safety assessment

Additional information

No bioaccumulation study is available for the cenospheres, but it can be concluded that cenospheres are not bioavailable for aquatic organisms due to its physical and chemicals properties as inert, hollow balls of sand-like material; Thus considering the extremely low recovery rate of ash contents, experienced from toxicological investigations and based on the structure-related properties of the substance, bioavailability and therefore bioconcentration of cenospheres contents is not expected.

The Tennessee Valley Authority (TVA) initiated two-phase laboratory sediment and surface water toxicity studies in the spring and summer of 2009. The objective of this testing was to determine whether constituents associated with fly ash including cenospheres found in site sediment and surface water are harmful to or are bio-accumulated by benthic invertebrates. The primary focus of the initial studies was on the potential for short-term effects associated with removing ash from the. The toxic effects endpoints measured include survival, growth and reproduction, and metals bioaccumulation elicited by exposure of benthic and aquatic species to whole ash, ash elutriates, dredge plume water, and ash stilling pond effluent. The results from these „A Multi-phased Toxicity Study for Evaluating Potential Risks of Kingston Fossil Plant Fly Ash Exposure to Benthic and Aquatic Biota“ ash composite samples indicated no appreciable bioaccumulation of metals in Corbicula fluminea exposures (28-d) to whole ash (R. Sherrard; poster, SETAC, 2009). The Bioaccumulation Factors (BAFs) are negligible, all BAF values for the measured heavy metals are below 1; the maximum BAF among metals was for zinc (mean = 0.343, range = 0.146 - 0.591 kg sediment (dry wt) / kg body weight (wet wt).

A second 4-day Lumbriculus variegatus toxicity test (pre-bioaccumulation test) shows also no significant difference between resin-treated ash and lab control and criteria for conducting 28-day bioaccumulation test were not met (R. Sherrard; Poster, SETAC, 2009 and Hydrosphere Research, 2009) and also in a field study with fish was no indication for a bioaccumulation potential of the fly ash including cenospheres. There were differences between sites in some indicators of exposure and effects in these fish collected 2-3 months after the spill, there were no consistent relationships between metal bioaccumulation and indicator responses and female fish collected at and downstream of the spill in spring/summer 2009 had no obvious significant reproductive abnormalities.

It can be therefore concluded that a significant bioaccumulation of ash contents including cenospheres is not expected and further bioaccumulation studies are not necessary.

Reference: R. Sherrard – Tennessee Valley Authority, Kingston Ash Recovery Project, Kingston, TN and Hydrosphere Research, 11842 Research Circle, Alachua, FL 32615, Ph. 386-462-7889 cited from: SETAC POSTER 2009 and: http://www.tva.gov/)