Originally Posted by hamburking
Years ago, I used automotive radiator antifreeze...the super toxic GREEN stuff. We aren't supposed to use that anymore because it gets into the ecosystem (Lake Ontario).
Urban legend, perpetuated by the folks that make PG and marine stores.
Both have effectively the same marine and freshwater toxicity, but don't believe me, read the MSDSs and the EPA report. Mammal toxicity and fish
toxicity is very different, which should not be a big surprise (we use galvanized pipe and zinc is required nutrient, but zinc is deadly to fish). Do avoid using EG in potable water systems,
but for engines and black water, it is better for the neoprene parts
(you can look that up too).
PG (red stuff)
EG (automotive, now many colors)
Both ethylene glycol and propylene glycol exhibit similar aquatic toxicity
characteristics. Acute and chronic tests have been performed for both glycols. Data were
Section 9.0 - Toxicity of Deicing/Anti-Icing Agents
acquired from several sources, particularly individual studies that performed similar tests on both
ethylene glycol and propylene glycol. Tests were performed on both freshwater and marine
aquatic life. Acute tests were performed to determine the lethal concentration for 50% of the
sample population (LC
) over a short period of time (48 to 96 hours). Chronic tests were
performed over a longer period of time (7 to 14 days).
Table 9-1 summarizes aquatic toxicity data from studies that directly compare
ethylene glycol and propylene glycol under the same or similar experimental conditions. In
general, the data show that ethylene glycol and propylene glycol exhibit aquatic toxicological
effects at concentrations within the same order of magnitude. Although EPA does not use such a
system, the U.S. Fish and Wildlife Service Classification System for Acute Exposures defines
“relatively harmless” as any chemical with an LC
above 1,000 mg/L (3). The test results shown
in Table 9-1 indicate that ethylene glycol and propylene glycol may be classified as “relatively
harmless,” as defined by the U.S. Fish and Wildlife Service