A federal bill designed to force antifreeze makers to add a bittering agent to their products is once again before the U.S. Congress, despite the fact lawmakers previously failed to consider two nearly identical measures.   

If enacted, H.R. 615, sponsored by Rep. Gary Ackerman, would amend the Federal Hazardous Substances Act to nationally require what already is mandatory in ten states and has been considered in a handful of others: Engine coolant must contain denatonium benzoate, the most bitter compound known, to render the sweet but toxic liquid unpalatable.

The goal of H.R. 615, or the Antifreeze Bittering Act of 2009, is to deter children and animals from drinking antifreeze. Ingesting just a tablespoon of ethylene glycol, the poisonous component in automotive antifreeze, can be lethal to a 10-pound cat. The Humane Society of the United States estimates that about 10,000 dogs and cats die from complications related to ethylene glycol toxicity each year, but other agencies guess that number to be much higher. Thousands of people are accidentally poisoned annually, states the American Association of Poison Control Centers. There also are reports of ethylene glycol-based antifreeze being used as a murder weapon.

Groups supporting laws that require aversive additives in antifreeze include the American Veterinary Medical Association and the Doris Day Animal League, which claims a national survey showed that two-thirds of veterinarians see cases of antifreeze poisoning each year. Doris Day did not elaborate about the source of the data, but statistics released by the Massachusetts Society for the Prevention of Cruelty to Animals (MSPCA), which also supports the federal legislation, seem to back those claims.

Of the 231 Massachusetts veterinarians that the MSPCA polled, nearly 68 percent reported treating animals for antifreeze ingestion, mostly dogs. The respondents conveyed a high mortality rate and spoke of the speed at which antifreeze poisoning causes irreparable damage to internal organs. Some also noted the client’s lack of understanding regarding the dangers of antifreeze.

Despite the serious nature of such poisonings, Ackerman’s previous attempts to federally mandate the addition of bittering agents in antifreeze were not well received. Introduced in both the 109th and 110th congresses, the bills never made it out of committee. One possible reason: The legislation was opposed by the Consumers Union, publisher of Consumer Reports, which expressed concern that denatonium benzoate is not biodegradable. The group warned that, due to antifreeze leaks in automobiles, denatonium benzoate could leach into ground and taint the flavor of drinking water.   

Now a recent study from the University of Virginia suggests that bittering agents do not effectively deter accidental antifreeze poisonings in humans. (The Impact of Bittering Agents on Pediatric Ingestions of Antifreeze. White et al. Clin Pediatr (Phila). 2009; 48: 913-921)

Using poison control data, researchers at the institution compared 232 cases of antifreeze ingestion by children less than five years old in California and Oregon — states that mandate the addition of a bittering agent to antifreeze — with 6,218 comparable cases in states without such a law.

Results showed that reported ingestions in Oregon and California were the same before and after the passages of antifreeze additive laws. The study also found that the amount of antifreeze ingested, observed clinical effects and need for treatment as well as the use of hospitalization were no different in California and Oregon than in other states.

The study's conclusion: “Despite the appealing logic of limiting the ingested volume and thereby the severity of poisonings by adding aversive agents, and despite promising results in volunteer studies, bittering agents do not decrease the frequency or severity of pediatric antifreeze poisonings.”

Ackerman spokesman Jordan Goldes said the congressman’s office does not know if state laws requiring bittering agents have translated to a reduction in animal poisonings. The VIN News Service found no reports of the impacts of these laws.

New Jersey is the latest state to require a bittering agent in antifreeze, via a bill that passed in January. Lawmakers in Ohio, Illinois, Massachusetts, New Hampshire and Georgia are considering similar measures.

Arizona, California, Maine, New Mexico, Oregon, Tennessee, Virginia, Vermont and Washington state already have such laws in place.

Antifreeze makers only add denatonium benzoate to product destined for these states, even though it costs just three cents a gallon to include the bittering agent, Goldes said.

Prestone maker, Honeywell Consumer Products Group, confirmed that statement.

Still, Mitchell Tracy, president of Market Active of Portland, Ore., the U.S. distributor of a popular brand of denatonium benzoate known as Bitrex, said he expects that the bittering of products containing ethylene glycol has developed a momentum of its own, regardless of what happens with currently proposed legislation.

“I would expect it to be in more and more products in more states now that more states already are requiring it,” he said.