coolant in bilge slumps

It won't hurt your fittings.

As to whether its environmentally friendly - did you drive to your boat ? Do others who suggest 'it isn't environmentally friendly' do they drive ? People in glass houses ...
 
No, but antifreeze isn't very environmentally friendly.

Good old fashioned ethylene glycol ain't too bad. From the WHO official assessment (www.who.int/ipcs/publications/cicad/en/cicad22.pdf‎):

Ethylene glycol is readily biodegradable in
standard tests using sewage sludge. Many studies show
biodegradation under both aerobic and anaerobic
conditions. Some studies suggest a lag phase before
degradation, but many do not. Degradation occurs in
both adapted and unadapted sludges. Rapid degradation
has been reported in surface waters (less in salt water
than in fresh water), groundwater, and soil inocula.
Several strains of microorganisms capable of utilizing
ethylene glycol as a carbon source have been identified.

Ethylene glycol has generally low toxicity to
aquatic organisms. Toxic thresholds for microorganisms
are above 1000 mg/litre. EC50s for growth in microalgae
are 6500 mg/litre or higher. Acute toxicity tests with
aquatic invertebrates where a value could be determined
show LC50s above 20 000 mg/litre, and those with fish
show LC50s above 17 800 mg/litre. An amphibian test
showed an LC50 for tadpoles at 17 000 mg/litre. A no-
observed-effect concentration (NOEC) for chronic tests
on daphnids of 8590 mg/litre (for reproductive end-
points) has been reported. A NOEC following short-term
exposure of fish has been reported at 15 380 mg/litre for
growth.


Even a full 5 litres of pure ethylene glycol would be diluted to LC50 for fish by 312 litres of water, which is a sphere 82cm across.

That's the blue antifreeze. I suspect that the corrosion inhibitors (alkaline in green, organic acid in orange) in antifreezes may be a little less benign.
 
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As to whether its environmentally friendly - did you drive to your boat ? Do others who suggest 'it isn't environmentally friendly' do they drive ? People in glass houses ...

Antifreeze isn't environmentally friendly. Just because we drive to our boats doesn't mean we're at liberty to hurl unnecessary poisonous stuff into the sea. You'll find that our honorary forum chemist, VicS, has pronounced on this many times, eg

Remember antifreeze is toxic so dispose of it safely
 
I use Windscreen washer fluide. Its cheap, doesnt freeze, has it doesnt damage the washers, piping etc. I guess it must be safe around the boats piping etc. If we splash it around when we clean our windscreens I guess its somewhat environmentally friendly
 
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