West Virginia Chemical Spill: NTP Studies
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 Evaluated in NTP Studies*
There was uncertainty regarding the exact concentrations of chemicals in the Freedom Industries storage tank that leaked into the Elk River. 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*
|Bacterial mutagenicity||Short-term tests to evaluate DNA damage in the bacteria S. typhimurium and E. coli caused by exposure to a chemical|
|High throughput screening assays||Assays to derive information about cellular and molecular targets and use for predicting potential biological effects|
|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|
|Nematode (Caenorhabditis elegans) toxicity||Short-term study to evaluate chemical effects over the life span of the organisms|
|Rat 5-day 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)|
|Rat 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|
|Structure-activity relationship analysis||A computational assessment that uses chemical structure to predict toxicological and biological properties|
|Zebrafish developmental toxicity and photomotor response||Short-term study to evaluate developmental effects in a vertebrate model system|
* All results from NTP studies can be accessed from Collective NTP Findings and Supporting Files.