The widespread advocacy for the use of 'salt water', in its many guises, for piercing aftercare is a very serious problem. The effect of salt water on a piercing will vary from none, in the best case, to extremely detrimental in the worst case. Those who advocate its use have not even taken the time to check their facts.
What is commonly known as 'normal saline' is a 0.9% w/v solution of sodium chloride (NaCl). It is made by disolving 9.0 grams (not 5 g, or 10 g, or a half teaspoon) of NaCl in 1.0 litre (not a cup, glass or jug) of water. To avoid confusion, most professionals will call this 'isotonic saline' ('Normal saline', note the capital 'N', is 58.54 g. per litre).
Isotonic saline has approximately the same osmotic pressure as extracellular (and intracellular) fluid and the net diffusion of water across the membranes of cells in contact with isotonic saline is unchanged. In other words, there is no change in the osmotic pressure of extracellular fluid when diluted with isotonic saline. (The concentration of solutes in body fluids is approximately 282 mOsmol/litre, that of isotonic saline is 308 mOsmol/litre.)
Two processes have to take place for isotonic saline (versus tap water) to make a difference.
- (1) The washing solution must mix with the extracellular fluids, and
- (2), the water from the extracellular fluids must diffuse into the cells to re-establish osmotic equilibrium. Both of these processes take time.
When irrigating a piercing with a hypotonic rinse, or water, the amount of mixing with extracellular fluids will be negligible, and the amount of water diffusing into the cells will also be negligible. The only effect of the extra water in the cells will be to increase their size, and even that, minimally and briefly, with NO detrimental effect on the tissues. Why go to the trouble of mixing hypo- or iso-tonic saline when tap water is just as good!
For those idiots who claim than isotonic saline has antibacterial properties, the intracellular fluid of bacteria has the same solute concentration as our body fluids. Isotonic saline has NO affect on bacteria!
If the concentration of salt is higher (hypertonic saline), then bad things start to happen. The exposed tissues are dehydrated as the net movement of water is out of the tissue and into the irrigating solution. Forget the Old Wives Tale about a poultice 'drawing the poison out'. Only water is removed!
Osmotic poultices and soaks have two purposes in the treatment of (major) injuries.
- The reduction of swelling associated with a major wound. This will relieve some discomfort, but it actually retards the healing process, and
- preventing a infected wound from healing and closing so the infected tissue remains accessible for treatment.
Salt water does NOT promote healing!
Source and Composition
The world's supply of sodium chloride comes from a single source: the ocean. Ever since our planet developed weather, rain has been washing the land masses and the run off has accumulated in the oceans. As the water evaporates and recycles, all of the dissolved rock, soil, decayed vegetation, sewage etc has remained in the oceans as salt.
Today we gather salt by evaporating sea water, or by mining the mineral halite, which is simply crystaline salt left behind from a prehistoric sea.
Sea salt, rock salt, table salt, pickling salt etc are ALL sodium chloride, with some trace calcium and magnesium chlorides (which are responsible for the caking we see on humid days). Table salt has a trace amount of sodium iodide as dietary iodine to prevent goiter in populations living inland away from the sea. The body will scavenge needed iodine and will eliminate unneeded iodine, so this addition has no detrimental effect.
Epsom salts are magnesium sulphate, occurring in nature as the mineral kierserite. Epsom salts are preferred over sodium chloride for osmotic poultices and soaks.
The acidity of a solution is specified as the Log of the reciprocal of the hydrogen ion concentration (as equivalents per litre). A pH of 1.0 is very acidic, and a pH of 14.0 is extremely alkaline. Pure water has a pH of 7.0.
Body fluids usually have a pH of 7.2 to 7.4, and the pH is controlled (buffered) by the solutes. Addition of acidic or alkaline substances produce relatively minor variations in hydrogen ion concentration. Although water, or a saline solution may have a significantly lower pH (6.0 to 7.0), adding it to a body fluid will not significantly alter the pH of the body fluid!
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