In January 2014, a chemical spill contaminated the drinking water in nine counties surrounding Charleston, West Virginia, in the United States. At the lab of Dr. Jennifer Freeman, Katharine Horzmann and her colleagues investigated the toxicology of the spill using zebrafish larvae as a biomedical model.
The chemical spill contained several compounds, but the first main focus was to analyze the possible health risks associated with the crude MCHM and its main component 4-MCHM. However, Horzmann and her colleagues investigated both these and the tank spill mixture, as different isomers of the MCHM might have different effects. In addition, a mixture of chemicals can have additive, synergistic, potentiated, or inhibitory toxicological effects.
To investigate the compounds, the researchers did an acute toxicity assay, morphological assessment, and visual motor response test.
The visual motor response test was conducted using DanioVision, during a white light routine in 96-well plates. At 28°C, larvae were exposed to alternating 10 minute periods of light and darkness, for 50 minutes in total. Several movement parameters were collected with EthoVision XT tracking software.
This study showed that the effects of the mixture, the crude MCHM, and the 4-MCHM differed. For example, while the acute toxicity increased with the complexity of the mixture (4-MCHM having the lowest acute toxicity, and the tank mixture having the highest), it did cause morphological changes at much lower doses than the tank mixture.
Horzmann, K.A.; Perre, C. de; Lee, L.S.; Whelton, A.J.; Freeman, J.L. (2017). Comparative analytical and toxicological assessment of methylcyclohexanemethanol (MCHM) mixtures associated with the Elk River chemical spill. Chemosphere, 188, 599-607.