National Toxicology Program

National Toxicology Program

West Virginia Chemical Spill: NTP Studies and Results

Latest Updates

Feb. 9, 2016: Access the supporting data for the February and June 2015 Updates for 5-day rat toxicogenomic studies. A link to the data has been added to the Table of Studies and Results.

Dec. 9, 2015: Web page format changed to improve clarity when supporting data were released.

The Centers for Disease Control and Prevention/Agency for Toxic Substances and Disease Registry nominated chemicals associated with the Elk River spill in West Virginia to NTP for toxicology studies. In response, NTP conducted a number of studies of relatively short duration to provide information relevant to the potential exposures of the Charleston residents.

The major constituents of the spilled liquid were of greatest concern, and these chemicals were studied in rodent and other model organisms to look for potential developmental effects. NTP also used cellular, molecular, and computer modeling approaches to try and identify what biological systems were affected. Chemicals of more limited concern, such as minor constituents of the spilled liquid, were evaluated using similar approaches.

A major focus of the toxicological characterization was to use efficient, medium, and high throughput testing methods to derive information for predicting the potential effects of the spilled chemicals.

Another significant consideration was the need to assess the potential for short-term exposures to result in long-lasting adverse health effects. Thus, several of the assessments evaluated effects on fetal and early life development, effects that are often irreversible.

NTP shared results from these studies on its website as they became available.

Table of Chemicals for NTP Studies

Chemical (Linked to Study Status) Also Known As CASRN* Reason Selected
Crude 4-methylcyclohexanemethanol Crude MCHM - Commercial product present in the leaking tank; a mixture of MCHM, MMCHM, MMCHC, DMCHDC, CHDM, and methanol
4-Methylcyclohexanemethanol MCHM 34885-03-5 Major constituent of the spilled liquid (>50% of the spilled chemical mixture)
1,4-Cyclohexanedimethanol CHDM 105-08-8 Minor constituents of the spilled liquid (estimated to be <10% of the spilled chemical mixture)
Dimethyl 1,4-cyclohexanedicarboxylate DMCHDC 94-60-0
Dipropylene glycol phenyl ether DiPPh 51730-94-0
4-(Methoxymethyl)cyclohexanemethanol MMCHM 98955-27-2
2-Methylcyclohexanemethanol 2MCHM 2105-40-0
Methyl 4-methylcyclohexanecarboxylate MMCHC 51181-40-9
Propylene glycol phenyl ether PPH 770-35-4
Cyclohexanemethanol, 4-[(ethenyloxy)methyl]- - 114651-37-5 Not a component of the spilled liquid; included because the compound is structurally related to MCHM
Cyclohexanemethanol, alpha,alpha,4-trimethyl- - 498-81-7
4-Methylcyclohexanecarboxylic acid - 4331-54-8
Phenoxyisopropanol - 4169-04-4 Not a component of the spilled liquid; included because the compound is structurally related to PPH
DOWANOL™ DiPPh - - A proprietary commercial mixture of DiPPh isomers, and DiPPh is a minor constituent of the spilled liquid

*CASRN is Chemical Abstracts Service Registry Number.

There was uncertainty regarding the exact concentrations of chemicals in the Freedom Industries storage tank that leaked into the Elk River. It was reported that the tank contained ~89% crude MCHM, 11% propylene glycol phenyl ethers, and 4% water. The product called crude MCHM is a commercial mixture containing >70% of MCHM along with lesser concentrations of five other chemicals. The propylene glycol phenyl ether component is also a commercial mixture, containing predominantly DiPPH and PPH in unknown concentrations. Even with this uncertainty, it was clear from the available information that the major contaminant of potential concern was MCHM. The other chemicals in the spilled liquid were each estimated to have been at 5- to 10-fold lower concentration. NTP’s toxicology studies focused on all chemicals known to be involved in the spill to qualitatively assess whether different types of effects would be expected and to quantitatively assess the concentration at which effects occurred.

Table of Studies and Results

Studies Description Updates and Data*
High throughput screening assays Assays to derive information about cellular and molecular targets and use for predicting potential biological effects Dec 2014 Update
Structure-activity relationship analysis A computational assessment that uses chemical structure to predict toxicological and biological properties Dec 2014 Update
Bacterial mutagenicity Short-term tests to evaluate DNA damage in the bacteria S. typhimurium and E. coli caused by exposure to a chemical Jun 2015 Update
Jul 2015 Update
Data (posted Nov 19, 2015)
Zebrafish developmental toxicity and photomotor response Short-term study to evaluate developmental effects in a vertebrate model system Jun 2015 Update
Jul 2015 Update
Aug 2015 Update
Nematode (Caenorhabditis elegans) toxicity Short-term study to evaluate chemical effects over the life span of the organisms Mar 2015 Update
5-Day rat toxicogenomic Short-term toxicity studies that identify subtle effects of a chemical on molecular processes in the liver and kidney and examine toxic effects in blood and damage to DNA (genetic toxicity) Feb 2015 Update
Jun 2015 Update
Data (posted Feb 9, 2016)
Mouse dermal irritation and hypersensitivity Assays to evaluate the ability of chemicals to cause skin inflammation by directly damaging cells (irritation) or by inducing an immune response known as allergic hypersensitivitiy or contact allergy Jun 2015 Update
Prenatal developmental toxicity A study where rats are exposed to a chemical throughout pregnancy to determine if it produces adverse effects on the developing fetus Dec 2014 Update
Jun 2015 Update
Data (posted Oct 2, 2015;
    format updated Dec 9, 2015)

*Supporting data files and reports are from studies conducted by NTP on chemicals associated with the Elk River spill in West Virginia. These data were used as the basis for the updates that NTP released in 2014-2015. The findings and reports from these studies have not undergone external peer review and may not represent the final conclusions of NTP or U.S. government. NTP will consider the findings from these studies in an overall assessment of the spilled chemicals that will undergo external peer review prior to publication.

NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.