Canadian water quality guidelines for glycols-An ecotoxicological review of glycols and associated aircraft anti-icing and deicing fluids

Abstract

This paper reviews the environmental fate, chemistry and toxicology of ethylene, propylene, and diethylene glycol, and their associated aircraft deicing/anti‐icing fluids. Ethylene glycol is currently the most prevalent glycol in Canada with high volume production and primary uses in deicing fluid and antifreeze mixtures and minor uses in polyester manufacturing. Propylene glycol use in Canada is concentrated in resin and polyester production whereas diethylene glycol is primarily used as a dehydrator in the natural gas industry. Glycols are miscible in water, and have very low log Kow, and log Koc values, which make these substances highly mobile. Aerobic biodegradation is the most important environmental fate process affecting glycols in waters and soils with available information demonstrating low persistence. Canadian monitoring data is limited to ethylene glycol where it has been routinely detected in stormwater runoff at airports. Glycols have relatively low aquatic toxicity, with algae being more sensitive than vertebrates or invertebrates. The most sensitive response recorded for ethylene glycol exposure was a 96‐h LOEC of 1923.4 mg L−1 for the green alga Selenastrum capricornutum. Aircraft deicing/anti‐icing fluids were more toxic than pure glycols. The most sensitive recorded response was a 96‐h LC50 of 18 mg L−1 for the fathead minnow Pimephales promelas, following exposure to a propylene glycol based anti‐icing fluid. The review details the development and derivation of the Canadian Water Quality Guidelines for glycols, including numerical concentrations for the protection of aquatic life. ©1999 John Wiley & Sons, Inc. Environ Toxicol 14: 481–522, 1999

Acute Toxicity of Storm Water Associated With De-Icing/Anti-Icing Activities at Canadian Airports

“…No significant differences between test facilities were observed for the D. magna, Rotoxkit, or Thamnotoxkit tests ( p Ͼ 0.05), whereas only slight differences were observed for the rainbow trout and the Microtox tests. Recent toxicity data on the ethylene glycol-based ADAFs currently used in Canada indicate LC50s for rainbow trout of 22,810, 17,368, and 251 mg/L for pure ethylene glycol, de-icer, and anti-icer products, respectively [1,2]. Differences in IQ test results may have resulted, in part, from differences in the mixing procedures or laboratory dilution water quality, but are more likely a result of subjectivity in endpoint measurements.…”

“…Differences in mixing procedures, laboratory dilution water quality (in the case of the rainbow trout test), or pipetting technique (in the case of the Microtox assay) may explain the differences observed. of 9,226, 1,181, and 54 mg/L for pure ethylene glycol, deicer, and anti-icer products, respectively [1,2]. Type II anti-icing fluid was not tested, but recent results indicate that these solutions are more toxic than either pure glycol products or de-icing solutions [2,7].…”

“…Exact formulations are proprietary and subject to change, but additive packages can include corrosion inhibitors, wetting agents, nonionic and anionic surfactants, buffers, antioxidants, and dyes [1,2]. In general, ADAFs are classified into two categories by their function and efficacy: Type I de-icing fluids, and Type II antiicing fluids.…”

Potential toxic effects of aircraft de-icers and wastewater samples containing these compounds

“…ADAFs consist of a minimum of 50 % of glycol, and the rest of the constituents include additives such as corrosive inhibitors, wetting agents, thickening agents and surfactants . The formulation of ADAFs is proprietary to the manufacturer, thereby making it difficult to understand the toxicity of different components of ADAFs concerning the environment (Kent et al 1999;US EPA 2000). The breakdown of ADAFs affords a high biochemical oxygen demand (BOD) and chemical oxygen demand (COD) due to the presence of glycol.…”

Design and development of anti-icing textile surfaces

“…When materials are exposed to high humidity and very low temperature, ice builds up on the top of the surface and causes a number of issues before and after de-icing [1][2][3]. For example, snow, slush, or frost accumulating on aircraft surfaces not only destroys the smooth flow of air but also increase drag during the take-off regardless of the actual weight of ice.…”