Anti-icing chemical may be toxic

News AASHTO Journal February 05, 2004
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The Federal Highway Administration is advising its field offices to be aware that a chemical sometimes added to anti-icing road

The Federal Highway Administration is advising its field offices to be aware that a chemical sometimes added to anti-icing road salt to prevent it from caking has been defined as a compound on the Environmental Protection Agency's toxic pollutant list for purposes of enforcing the Clean Water Act.

Although ferric ferrocyanide, often referred to as "Prussian Blue," has been used for years to keep road salt free-flowing without apparent insult to the environment, FHWA advised its field offices late in October to be aware of the EPA determination, which was published in the Federal Register on Oct. 6, 2003.

While the cyanide component in ferric ferrocyanide (FFC) is normally chemically bound to its other components, preventing it from having a toxic effect, EPA found that the compound "under exposure to certain environmental conditions" could break down and release cyanide, which is highly toxic. The conditions in question were not specified in the Federal Register entry.

In its memo, FHWA noted that the conditions that could cause the breakdown of ferric ferrocyanide into its component elements "are highly unlikely, and state highway agencies . . . have used road salt containing FFC and a similar cyanide compound, sodium ferrocyanide (SFC) for decades without incident." FHWA also noted that it advised EPA about potential negative highway operations and safety effects that the toxic designation could trigger.

However, FHWA states, "EPA indicates that states should not have to change any current practice regarding the use of road salt containing FFC" regarding compliance with the Clean Water Act or the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).

"EPA has advised us that no CERCLA cleanup action due to FFC in road salt has ever been undertaken by EPA, or for that manner by any other party. Nevertheless, we think the potential for increased litigation, adverse public reaction and other possible liabilities due to the EPA determination remains a concern to the highway program," FHWA noted.

Further, states "should be aware that EPA in the future could establish FFC as a reportable toxic pollutant with revised regulations under the CWA and CERCLA." And, even though reporting is not currently required, there still could be potential liability under CERCLA for required cleanup costs associated with a cyanide contamination problem, FHWA advised.

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