Toxicity of sea water in mammals.

T HE effects of administering sea water and similar solutions to animals, and occasionally to human beings, have been studied sporadically. Semipopular accounts of the gross effects of the drinking of sea water by shipwreck victims exist (I). During World War II the torpedoing of ships at sea and the loss of planes over open ocean, setting survivors adrift in lifeboats and on rafts, gave impetus to careful investigation of the question whether it is beneficial or harmful for castaways to drink sea water (2-5). The present studies, on several species, were designed to elucidate the following questions: a) How much sea water can be tolerated by mammals, and by which routes of administration? b) What animals are most resistant to the toxic effects of sea water? c> What bodily effects do lethal and sublethal doses of sea water exert? d> How do excess salts and water distribute themselves? e) How may animals’ resistances to sea water be modified, if at all?f) Can animals be induced to drink sea water? These questions bear not only upon the toxicity of sea water for men who are forced to drink it or nothing, but also upon physiological regulations of water and salt in mammals. The composition of sea water might suggest the nature of its toxic effects: does sea water cause damage to men and animals simply by dehydrating them through its high osmotic concentration, or are one or more of its ions specifically toxic? These studies included the use of several solutions: artificial sea water prepared approximately according to the formula of Harvey (6); sea water from Woods Hole, Massachusetts; water from the Gulf of Maine; and solutions of MgClz, of NaCl, of sucrose and of urea. The Woods Hole sea water is assumed to have had the composition reported for it by Page (7); our chloride analyses agreed very closely with his. The salinity of sea water averages 3.4 per cent (0.58 molar), though it varies in different localities. The proportions of the diverse ions in sea water also vary somewhat, but the Clion is most abundant and the Na+ ion is next, and these two together far exceed all other ions combined (6). Concentrations of Na+ and Clin sea waters are three to five times as great as the normal concentrations of these ions in human serum; of Mg *, four times that serum concentration which causes death from cardiac arrest in mammals, and seven times that serum concentration which causes cessation of respiration; Ca++ and R-t in sea water are about two-thirds of the fatal serum Ca++ and K+ concentrations in mammals. All of the other ions in