The Myth of Pre­vent­ing In­fec­tion by Rins­ing with Sea­wa­ter

RECOIL OFFGRID - - Debunked - By Pa­trick McCarthy

Imag­ine for a mo­ment that you’re stranded on a re­mote coastal shore­line. As you climb over the slick rocks, your foot slips and you fall for­ward, slam­ming your fore­arm against the edge of a sharp stone. Feel­ing dizzy and nau­se­ated, you ex­am­ine your arm and see a deep bleed­ing gash flecked with sand and grit from the fall.

The Myth

Reel­ing from your in­jury, you re­call hear­ing that salt­wa­ter can kill bac­te­ria, and you know that hos­pi­tals of­ten rinse wounds with saline so­lu­tion. So, you con­tem­plate wash­ing out your wound with sea­wa­ter with the hope of pre­vent­ing in­fec­tion. Un­for­tu­nately, it’s likely that do­ing so will make your sit­u­a­tion even worse.

De­spite per­va­sive claims about in­fec­tion pre­ven­tion, the sci­en­tific con­sen­sus is clear: rins­ing your wounds with sea­wa­ter is dan­ger­ous.

The Re­al­ity

Like most myths, the sup­posed heal­ing prop­er­ties of sea­wa­ter are founded on a grain of truth. Salt is cer­tainly ca­pa­ble of pre­vent­ing the growth of some types of bac­te­ria. High salt con­cen­tra­tion in liq­uid cre­ates a hy­per­tonic so­lu­tion that pulls mois­ture out of sus­cep­ti­ble bac­te­ria cells via os­mo­sis, slowing or stop­ping their growth.

For thou­sands of years, salt cur­ing has been used to pre­serve meat, and salt was used as a prim­i­tive an­ti­sep­tic in an­cient Egypt, Greece, and Rome. You’ve prob­a­bly heard the phrase “rub­bing salt in a wound,” a say­ing that’s ru­mored to have orig­i­nated from sailors who would rub the crys­tals on the cuts they re­ceived from lash­ings. Salt in these wounds in­ten­si­fied pain and caused scar­ring, but the men suf­fered through it in a des­per­ate at­tempt to avoid deadly infections.

Gar­gling warm salt­wa­ter can be ben­e­fi­cial for oral health, as men­tioned in our health col­umn, Off-the-Grid Den­tistry, else­where in this is­sue. Most no­tably, saline so­lu­tion is widely used by med­i­cal pro­fes­sion­als to ir­ri­gate wounds. How­ever, there are two crit­i­cal dif­fer­ences be­tween med­i­cal saline and sea­wa­ter.

Salin­ity: Med­i­cal saline is iso­tonic, and typ­i­cally con­tains 0.9-per­cent salt to mimic the body’s nat­u­ral salin­ity — that’s why there’s no ex­cru­ci­at­ing burn when it’s ap­plied. Saline ir­ri­ga­tion is in­tended to flush out the wound rather than kill bac­te­ria on a cel­lu­lar level.

Sea­wa­ter is hy­per­tonic, with salin­ity of about 3.5 per­cent. This causes a painful sting­ing sen­sa­tion as it draws wa­ter out of the ex­posed cells in a wound. The higher salin­ity is ca­pa­ble of killing some types of bac­te­ria, but other salt-tol­er­ant micro­organ­isms thrive in sea­wa­ter. This leads to our next point.

Steril­ity: Med­i­cal saline won’t in­tro­duce new bac­te­ria into your wound, but sea­wa­ter is far from pure. It can con­tain traces of hu­man pol­lu­tion, such as sewage or chem­i­cal runoff, and it’s teem­ing with a va­ri­ety of micro­organ­isms, in­clud­ing:

Di­noflag­el­lates that cause red tide and pro­duce harm­ful biotox­ins

En­teric viruses that cause gas­troen­teri­tis, hepati­tis, my­ocardi­tis, and asep­tic menin­gi­tis

Pro­to­zoan cysts such as cryp­tosporid­ium and gi­a­r­dia, which are washed out from fresh­wa­ter sources and can re­main in­fec­tious for up to 12 weeks in sea­wa­ter

Staphy­lo­coc­cus au­reus, the bac­te­ria that causes staph infections Vib­rio bac­te­ria, a cat­e­gory that causes se­ri­ous dis­eases. This in­cludes V. cholera, the bac­te­ria strain re­spon­si­ble for the in­fa­mous dis­ease of the same name.

In an es­say pub­lished by ABC News, Wake For­est Uni­ver­sity Pro­fes­sor John G. Span­gler, M.D. wrote, “Marine vib­rios can in­fect the blood­stream, caus­ing po­ten­tially fa­tal ill­ness. Skin infections, which oc­cur when open wounds are ex­posed to sea wa­ter, can lead to large ar­eas of blis­ter­ing as well as deep skin and mus­cle infections. These also are ex­tremely dan­ger­ous and of­ten fa­tal.”

The Al­ter­na­tives

Know­ing the risk of in­fec­tion from sea­wa­ter, it’s worth con­sid­er­ing al­ter­nate treat­ments that could be ap­plied in sce­nar­ios such as our hy­po­thet­i­cal beach­comb­ing in­ci­dent.

Ster­ile saline is an easy choice, but you prob­a­bly won’t have any un­less you’re car­ry­ing a first-aid kit. Don’t bother try­ing to im­pro­vise your own saline with ta­ble salt — get­ting the cor­rect pH and iso­tonic salt con­cen­tra­tion while main­tain­ing steril­ity isn’t fea­si­ble out­side a lab.

For­tu­nately, clin­i­cal stud­ies have in­di­cated that saline so­lu­tion isn’t sub­stan­tially more ef­fec­tive at pre­vent­ing in­fec­tion than clean tap wa­ter. In fact, a clin­i­cal study pub­lished in 2013 in the BMJ Open med­i­cal jour­nal found that slightly fewer infections oc­curred when us­ing tap wa­ter, call­ing it “a safe and cost-ef­fec­tive al­ter­na­tive to saline so­lu­tion for wound ir­ri­ga­tion.”

This means you can sim­ply rinse your wound thor­oughly with clean drink­ing wa­ter. Proper wound ir­ri­ga­tion re­quires some pres­sure to wash away de­bris — this can be achieved by squirt­ing wa­ter out of a clean sy­ringe, squeeze bot­tle, or even a plas­tic bag with a slit in the cor­ner. Then, ap­ply a dress­ing to keep the wound clean and do your best to find some an­tibi­otic oint­ment, or bet­ter yet, a hospi­tal.


WARN­ING: This ar­ti­cle is meant to be a quick over­view and not a de­tailed guide on emer­gency wound care. Pro­fes­sional med­i­cal treat­ment should al­ways be sought be­fore at­tempt­ing any of these meth­ods.

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