Who knew? [Excerpt below from BNA; full text requires subscription]
USGS Claims De-Icing Agents Toxic to Environment
A new U.S. Geological Survey study found anti-corrosion agents in aircraft deicers and anti-icers are the main ingredients polluting stormwater runoff at airports.
"Most potentially toxic and endocrine disrupting effects caused by aircraft deicer and anti-icer fluids are due to the numerous additive package ingredients, which vary among manufacturers and types of aircraft deicer and anti-icer formulations," the USGS said in the study released by the American Chemical Society Aug. 8.
Anti-icers are thick viscous fluids used on aircraft to prevent ice and snow accumulation, whereas deicers are fluids used to remove snow and ice buildup on aircraft.
A deicer and an anti-icer contain mostly propylene glycol, ethylene glycol, or diethylene glycol to depress the freezing points of ice and snow. They also contain varying levels of water and other additives, such as benzotriazole and benzotriazole derivatives, to inhibit corrosion and other compounds used as flame retardants.
The Federal Aviation Administration requires airlines and airports that operate during icy conditions to perform deicing and anti-icing of aircraft and airfield pavement.
When performed without discharge controls in place, "these deicing operations can result in environmental impacts," according to EPA.
The USGS study was released as the Environmental Protection Agency is assessing whether anti-icers and deicers at airports should be regulated. EPA expects to propose a rule on the use of deicers and anti-icers by December 2007, with final action expected by September 2009.
In April, EPA sent out questionnaires to 153 airports seeking information about deicing activities to assess whether the agency needs to develop effluent guidelines for airports. Effluent guidelines are regulations that control the discharge of pollutants to surface waters and to publicly owned treatment works (73 DEN A-7, 4/17/06 a0b2q8a9j0 ).
EPA has not regulated deicing activities until now because it never considered airports to be industrial dischargers subject to effluent guidelines. EPA said the results of the questionnaires will assist it in determining how to move forward with a rulemaking.
Additives in Deicers, Anti-Icers Implicated
The purpose of the USGS investigation was to study the effects of anti-icers and deicers on lakes, streams, or rivers.
Steven Corsi, a research hydrologist with the USGS in Middleton, Wis., and his colleagues say their study and others have "implicated" additives in the anti-icers and deicers" as the primary source of deicer- and anti-icer-toxicity.
Corsi told BNA that he looked at the toxicity levels and effects of additives in nine aircraft deicers and anti-icers on four aquatic creatures--green algae, minnows, bacteria, and water fleas. He concluded that anti-icers are more toxic than deicers based on the responses of the aquatic organisms to low and high levels of exposure.
Corsi and others performed acute and chronic toxicity tests using five types of deicers and four types of anti-icers. An acute test generally involves an exposure to a single chemical at a high concentration over a short period of time; a chronic test involves exposure over a longer period of time using low concentrations of a chemical.
Low Levels Indicate Higher Toxicity
The tests showed that acute toxicity endpoints for deicers ranged from 1,550 milligrams per liter (mg/L) to 45,100 mg/L, depending on the type of deicer used. Likewise, the acute toxicity endpoints for anti-icers ranged between 347 mg/L and 7,700 mg/L.
Chronic endpoint concentrations ranged from 70 mg/L to 1,300 mg/L for anti-icers and 37 mg/L to 18,400 mg/L for deicers. An toxicity endpoint is one where a scientist observes measurable responses to a chemical.