I read this about the many poisonings by antifreeze in wikipedia:
For this reason bittering agent (denatonium benzoate) is usually added to engine coolant to make it taste unpleasant. In the United States, there is legislation before Congress (H.R.2567/S.1110) that would make the use of a bittering agent mandatory.
Propylene glycol, on the other hand, is considerably less toxic and may be labelled as "non-toxic antifreeze". It is used as antifreeze where ethylene glycol would be inappropriate, such as in food-processing systems or in pipes in homes, as well as numerous other settings. It is also used in food, medicines, and cosmetics, often as a binding agent. Propylene glycol is "
generally recognized as safe" by the
Food and Drug Administration (FDA) for use in food. However, it should not be thought that propylene glycol based antifreeze is safe for consumption. In the event of accidental exposure emergency medical services should be contacted.
In the 1980s inventor Jack Evans discovered the advantages of using a waterless coolant. His final formulation is a mixture of ethylene glycol and propylene glycol. This coolant has a high boiling point of 370 °F and is not corrosive, solving many of water's problems including freezing.
Most commercial antifreeze formulations include
corrosion inhibiting compounds, and a colored
dye (commonly a
green,
red or
blue fluorescent) to aid in identification. A 1:1
dilution with water is usually used, resulting in a freezing point of approximately −40 °F (−40 °C). In warmer areas weaker dilutions are used.
Glycol antifreeze solutions should generally be replaced with fresh mixture every two years. Many modern cars now come filled with organic acid technology (OAT) antifreeze (such as
Dex-Cool[1]), which has an extended service life of five years. Although these still contain glycol, OAT solutions may not be compatible with conventional inorganic-based coolants containing glycol (e.g., with silicates, borates, phosphates) and, if changing from one type to the other, the cooling system must be thoroughly flushed with clean water.<SUP class=noprint>[
citation needed]</SUP> Typically OAT antifreeze contains a red or pink dye to differentiate it from the conventional inorganic coolants (blue or green). Some of the newer technology OAT coolants claim to be compatible with
all types of OAT and inorganic-based coolants; these are typically green or yellow in color.
Take caution in mixing antifreezes. The problem becomes when you mix a standard coolant with a newer engineered coolant, they actually create an acid that eats at aluminum and rubber. Also the newer coolants generally require very specific type cooling systems. You cannot use the newer coolants in older style cars that never received an engineered coolant from the factory. The radiators will not be efficient enough for the coolant and they are made of materials that the coolant corrodes.
If ingested, the antidote for antifreeze is usually
ethanol or
fomepizole.
