How toxic is coal ash? A laboratory toxicity case study

Abstract

Under a consent agreement among the Environmental Protection Agency (EPA) and proponents both for and against stricter regulation, EPA is to issue a new coal ash disposal rule by the end of 2014. Laboratory toxicity investigations often yield conservative estimates of toxicity because many standard test species are more sensitive than resident species, thus could provide information useful to the rule-making. However, few laboratory studies of coal ash toxicity are available; most studies reported in the literature are based solely on field investigations. This brief communication describes a broad range of toxicity studies conducted for the Tennessee Valley Authority (TVA) Kingston ash spill, results of which help provide additional perspective on the toxicity of coal ash. Integr Environ Assess Manag 2015;11:5-9. © 2014 SETAC

The Effect of Dietary Exposure to Coal Ash Contaminants within Food Ration on Growth and Reproduction in Daphnia magna

“…Although we found significant effects of coal ash exposure on daphnid growth and reproduction, these effects were not severe enough to threaten the population at the concentrations of ash considered in our study as estimated by specific population growth rates ( r ). However, the concentrations of ash used in the present study were significantly lower than those used in previous studies (Greeley et al 2014; Sherrard et al 2015) and could be significantly lower than those that organisms would be exposed to in a coal ash–contaminated environment. Food limitation had a much greater impact on the viability of Daphnia populations, and under food‐limiting conditions, exposure to coal ash contaminants had a positive effect on population viability because survival and reproduction increased with increasing ash concentration in the low food treatment.…”

“…Although the relevance of dietary exposure to toxicants is increasingly recognized (Hook and Fisher 2001b; Wang 2011), most standard toxicological studies expose organisms to aqueous toxicants, which can significantly underestimate risk. In the present study dietary exposure to relatively low ash concentrations resulted in sublethal effects in D. magna (Figures 2 and 3), but previous laboratory studies have reported no toxicity in Ceriodaphnia dubia or in fathead minnows ( Pimephales promelas ) exposed to much higher coal ash concentrations through aqueous or sediment exposure (Greeley et al 2014; Sherrard et al 2015). Because most toxicants need to be taken up into the body (e.g., through respiration, absorption, ingestion, etc.)…”

“…Ecological risk assessments often rely on short‐term toxicity tests that involve exposure to aqueous contaminants (Stewart and Konetsky 1998; US Environmental Protection Agency 2002; Sherrard et al 2015). These tests may not be sensitive enough to detect sublethal impacts of contaminants deriving from exposure to Se or Hg that may occur through chronic dietary exposure.…”

Application of ecological risk assessment in managing residual fly ash in TVA's Watts Bar Reservoir, Tennessee

“…Statistically significant reductions in survival, biomass, or emergence of test organisms ( Hyalella azteca and Chironomus dilutus ) occurred in some Emory River sediment toxicity tests. The sediments in these tests contained a wide range of ash concentrations and included a series of dilutions with upstream reference sediments (Stojak et al , this issue; Sherrard et al , this issue). These results suggested at most a moderate level of risk to the benthic invertebrate community, and were augmented by the presence of ash‐related COPECs in sediments and benthic invertebrate tissues at concentrations reported in the literature to have caused adverse effects.…”

In vitro and in vivo toxicity of coal fly Ash Lechate

“…A broad range of toxicity studies was conducted after the 2008 TVA Kingston ash spill into the Emory and Clinch rivers to evaluate potential effects of fly ash on aquatic biota. The study demonstrated that the risks to resident species were moderate and limited to locations with ash content greater than 40% ( Sherrard et al, 2015).Moreover,the Emory-Clinch system after its remediation presented low risk of excessive element exposure and limited adverse reproductive effects to freshwater turtles (Steen et al, 2015).…”