Good News For Pets: Bitter Agent Added to Antifreeze Sold in the US

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Antifreeze and Engine Coolant Being Bittered Nationwide as Industry agrees to voluntarily take steps to protect pets, wildlife and children.

Antifreeze kills. The common chemical additive, used in automobile engines and the winterization of plumbing in summer homes, is easily encountered by pets, with usually horrible and fatal results. While several US states have enacted regulations requiring that a bitter tasting agent be added to repel pets, most have not, and the industry has been perceived to be slow to move on its own.

The industry has now taken the huge step of agreeing to voluntarily add the bitter agent to their antifreeze products. The decision was announced earlier this month in the following statement:

The Humane Society Legislative Fund and Consumer Specialty Products Association jointly announce an agreement to voluntarily add a bitter flavoring agent to antifreeze and engine coolant manufactured for sale for the consumer market in all 50 states and the District of Columbia  to prevent animals and children from being poisoned by the sweet-tasting liquid. Poisoning occurs because animals are attracted to the sweetness of antifreeze and engine coolant, which inadvertently spills in our driveways or is left in open containers in garages.

“This is a ground-breaking example of what’s right with Washington,” said Sara Amundson, executive director of the Humane Society Legislative Fund. “After years of battling over legislation addressing this important issue, the manufacturers of antifreeze and engine coolant have been working with animal advocates to pass state laws with mutually-agreed on language. Now, the Humane Society Legislative Fund applauds them for taking this important step to help protect our pets, kids and wildlife in every state.”

HSLF estimates range from 10,000 to 90,000 animals poisoned each year after ingesting ethylene glycol, the highly toxic substance used in auto antifreeze and coolant. Ethylene glycol’s sweet smell and taste make it attractive to animals as well as children. The manufacturers are adding bitter-tasting denatonium benzoate to antifreeze and coolant sold directly to consumers across the country.

“Partnering with the Humane Society Legislative Fund in passing these laws in 17 states has shown by finding compromise and working together we can develop sound public policy. It is vital that consumers continue to read the labels and follow label instructions on the proper use, storage and disposal of antifreeze.  Today, all major marketers are placing the bitterant in antifreeze in all 50 states,” said Phil Klein, executive vice president, legislative and public affairs for CSPA.


  • Seventeen states currently require the addition of the bittering agent to antifreeze and engine coolant: Arizona, California, Georgia, Illinois, Maine, Maryland, Massachusetts, New Jersey, New Mexico, Oregon, Tennessee, Utah, Vermont, Virginia, Washington, West Virginia and Wisconsin.
  • Oregon passed the first state law and it has been in effect since 1991.
  • In one survey, two out of three veterinarians reported that they had treated at least one case of antifreeze/engine coolant poisoning each year.
  • One teaspoon of antifreeze or engine coolant can kill an average-sized cat.
  • Denatonium benzoate has been used in common household products and as an anti-nail biting formula for decades in the United States.




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