State Water Resources Research Institute Program

Project Id: 2010OH169B
Title: The Environmental Fate and Transport of Denatonium Benzoate
Project Type: Research
Start Date: 3/01/2010
End Date: 2/28/2010
Congressional District: 3
Focus Categories: Solute Transport, Groundwater, Sediments
Keywords: adsorption, quaternary ammonium compounds, bittering agents, soil, organic matter
Principal Investigator: Crosson, Garry S (University of Dayton)
Federal Funds: $ 25,430
Non-Federal Matching Funds: $ 50,862
Abstract: The proper stewardship of water supplies is essential to human health and quality of life. As such, the use of any material that could negatively impact natural water supplies should be done with caution. Recently, the Ohio House of Representatives introduced H.B. 96 mandating the addition of the bittering agent denatonium benzoate, a water soluble salt, to automobile antifreeze; this legislation parallels The Antifreeze Bittering Act of 2009 proposed by a U.S. House of Representatives subcommittee. Although well intentioned, no consideration was afforded to the fundamental question of: What will be the fate of denatonium benzoate if released (intentionally or unintentionally) to the environment? The answer is very important in the context of environmental policy and law. To date, no published studies are available addressing potential deleterious effects and the environmental fate and mobility of denatonium benzoate. This compound is potentially problematic for natural waters given the fact that it is the most bitter compound known and can render waterways unpalatable at low concentrations. In 2005, American Water Works Representative, Tom Bonacquisti, Director of Water Quality and Production, Fairfax County, VA highlighted this fact in an address to the Environment and Hazardous Materials Subcommittee, of the House of Representatives Energy and Commerce Committee pertaining to The Antifreeze Bittering Act of 2005 (H.R. 2537). The proposed research addresses the natural attenuation (or enhancement) of mobility by studying denatonium benzoate sorption at mineral/water interfaces.

It is hypothesized that the sub-surface mobility of DB when released to the environment will be determined by soil interactions. Hence, the mobility of DB will be different for various soil types (e.g. coarse grained, fine-grained, highly organic, etc.) and soil solution conditions (ionic strength, pH, dissolved organic matter type and amount). To test this hypothesis we will characterize the adsorption properties of DB on a diverse group of minerals using well-established macroscopic batch sorption methods. DB sorption/desorption will be monitored using GC-MS and HPLC methodologies. The specific objectives of the research are to:

  1. Characterize the sorption and desorption behavior of the denatonium cation to (and from) clay surfaces
  2. Delineate the role of solution chemistry (pH, ionic strength, cation type) and temperature in the partitioning of the denatonium cation between aqueous and solid phases.
  3. Determine the sorption mechanism of the denatonium cation to clay surfaces.

Preliminary results, from my lab, of denatonium benzoate sorption to sand, aluminum oxide, and hectorite clay indicated that denatonium benzoate does not adsorb to sea sand (silica) or aluminum oxide but does sorb to hectorite clay (a major constituent of some soils). Solid-phase spectroscopic (FTIR and NMR) measurements of DB/clay complexes will also provide invaluable insight into interaction mechanisms. The methods used to accomplish this research are well-established; however, the research is unique in that we seek to proactively study a potential contaminant which is yet to be proven detrimental to human health or the environment. This research will help facilitate wise decisions regarding the use of DB and related compounds by legislators (particularly in the case of the Bittering Act), policymakers at Environmental Protection Agency and related agencies charged with making decisions that impact human health.

Progress/Completion Report, 2010, PDF

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