Copper is an aquatic hazard?

[Adam Funk]

I got a package today with the "dead tree & fish" label on it & a

13-page safety data sheet inside. It turns out that desoldering braid is so labelled because copper is "aquatic acute 1, H400" and "aquatic chronic 1, H410". (The other component, rosin, is marked as "skin sens. 1, H317".)

I'm a bit surprised that copper is apparently safe to contain & carry drinking water but a hazard if dropped in water outside. What am I missing here?

[Chris Hogg]

Stuff here:

Copper is potentially toxic to a lot of life forms, depending on the life form and copper concentration, although it sounds as though the safety data sheet in your package is an example of COSHH and H&S gone quite stupid, certainly more so than usual.

[harry]

[Martin Brown]

The surface area to weight ratio. Copper pipe isn't that easy to dissolve whereas desolder braid will rot away quite quickly. It can be quite bad for fish. It is true for all heavy metals to a greater or lesser extent even iron which we need for haemoglobin can be toxic.

I recall a copper tainted well not far from here which in times past resulted in a lot of unexplained illness in the people who used it. There were a fair number of copper mines round here in the distant past. It isn't clear if arsenic colocated with the copper mineral vein wasn't at least partially responsible for their problems.

Some copper mine spoil heaps have grass that has adapted to growing on highly copper rich soils where there is almost no competition. Humans can normally tolerate some copper in their diet but certain breeds of sheep and dairy cows are prone to concentrating it and then expiring.

(and links therein)

[Chris Hogg]

You live in west Devon, Cornwall or on Anglesey?

[Adam Funk]

RS Components are pretty thorough about H&S labelling & data sheets.

[Adam Funk]

That all makes sense, thanks. The other thing I thought of after posting the question is that "outside" water might be acidic or otherwise more capable of dissolving copper than drinking water is.

[Chris Green]

There's also the possibility that water animals (especially those with gills?) may be more susceptible to copper than we are. Poisons can be quite species specific sometimes.

[Nightjar]

Wooden ships used to be sheathed in copper in order to prevent marine life from growing on the hull. SFAIK it is still used in antifouling paints.

[Martin Brown]

Increasingly the antifouling paints are inert and extremely slippery as this both prevents marine life getting stuck on and decreases friction against the water by over 5% (and a big saving in fuel bills).

The days of noxious paints on boats polluting harbour waters is almost at an end. Older boats may still have TBT and other nasties on them - but use of that stuff was officially banned in 2008 and strongly discouraged for a while before that.

[Brian Gaff]

Sounds bonkers except of course it sounds like somebody is going to make money out of it. Brian

[Brian Gaff]

Yes its used to stop moss growth, also of course copper can be turned into nasty stuff if used in salt water. Brian

[spuorgelgoog]

The effect of copper that prevents things growing in the water is beneficial to us as it prevents nasty things growing in our drinking water - at least in the concentrations to be found in drinking water.

It's the same as chlorine - very nasty stuff, but in the concentrations in drinking water (or swimming pool water) it kills more bugs than it harms us.

Owain

[Andrew]

The gunpowder stores on Royal Navy ships were lined with copper too, but I believe this was to prevent rodents gnawing their way in and then leaving a trail of gunpowder leading back to the bulk store. Boom.

[alan_m]

Also the prevention of sparks.

[Adam Funk]

Now that you mention it, I've seen aquarium instructions advising against using hot tap water because it contains more dissolved copper than cold.

[Reentrant]

I've kept freshwater tropical fish for nearly 50 years. Copper sulphate is the traditional cure for snail infestations and some parasites.

Obviously too much will be toxic but at the right concentration it can kill invertebrates but harmless to fish and plants.

I use a mixture of (cold) rainwater and (hot) tap water for weekly changes, but the cylinder and pipes are probably so scaled up with Hampshire's finest from chalk boreholes that it doesn't touch any copper.

[tabbypurr]

I knew tropical fish keepers, some of whom used cold tap water. One day one of them had new copper plumbing fitted, used the water and the fish all died. The pipes were not scaled. Like any nutrient or toxin, dose is everything.

NT