THE CHEMICAL ENVIRONMENT 435

75Se was increased due to decreased urinary excretion, and the uptake by the viscera (with the exception of the liver) increased, but when the diet of the cirrhotic rats was supplemented with Se for 14 days prior to the experiment, these changes, apart from increased renal up- take, were reversed. In normal rats pretreated with Se, however, 75SEO4 metabolism was un- affected, suggesting that the choline-deficient diet also produced Se deficiency in these cirrhotic animals.

These findings thus show not only that the metabolic fate of SeO4 varies with the dose administered and with the pathological and nutritional state of the liver, but that organic Se is retained in the body to a greater extent than inorganic Se. It will be recalled that the toxicity of seleniferous plants is probably due to selenoamino acids (Cited in F.C.T. 1966, 4, 86).

Hadjimarkos (cited above) determined the Se content of milk since children are most susceptible to Se-induced caries. Five samples of evaporated milk were found to contain from 0.01 to 0.04 ppm Se. These values are similar to those found in human milk from mothers living in non-seleniferous areas of Oregon and in cow's milk obtained from a region of Oregon where the incidence of caries and the urinary excretion of Se is low among children. The values were lower than in cow's milk (0.06 ppm) from two other regions of the same county where caries were prevalent and the urinary excretion of Se was high among children. Although these concentrations of Se in evaporated milk are low, the US Public Health Service have set the limit of safety of Se in drinking water at 0.01 ppm. A knowledge of the long-term effects of very low concentrations of Se is obviously required.

1315. The silver lining Bader, K. F. (1966). Organ deposition of silver following silver nitrate therapy of burns. Plastic reconstr. Surg. 37, 550.

We have already pointed out that very little silver (Ag) passes through intact skin (Cited in F.C.T. 1966, 4, 89). The topical treatment of extensive burns with silver nitrate (AgNO3) solutions, though clinically useful, is not devoid of potential hazard. Organs from two patients treated in this way with 0.5 % AgNO3 for short periods showed 0.14 to 2 ppm Ag instead of the normal 0.025 ppm. Evidently Ag enters the circulation in significant quan- tities and is deposited in tissues, particularly liver, kidney, spleen and muscle. The physio- logical significance of this effect is unknown.

1316. More about the Canadian beer mystery Morin, Y. (1966). Quebec's medical mystery. J. Am. med. Ass. 197, 592.

Mystery still surrounds the cause of the recent deaths in Canada attributed to beer drinking (Cited in F.C.T. 1967, 5, 120) but the clinical and pathological features presented by the victims appeared to be quite specific.

The onset of the disease, which had a 40-50 ~o mortality rate, was heralded by symptoms of cardiac insufficiency. Biochemical studies revealed a high haematocrit value, a low serum iron level, increased activity of serum enzymes (unspecified) and a rise in serum bilirubin. Pathological damage was manifest in the heart, lungs, intestinal tract and thyroid. Histo- logically, the heart showed interstitial oedema, hydropic degeneration of the muscle cells, without inflammatory reactions, and the presence of thrombi. Centrilobular necrosis of the liver, acute ulcerations and haemorrhages in the gastro-intestinal tract and epithelial hyper- plasia of the thyroid were the other principal histological findings.

1317. Ozone and the lungs Wanner, H. U. & Gilgen, A. (1966). Untersuchungen tiber Raumozonisatoren und tiber Ozon-Vorkommen in der Aussenluft und in Industriebetrieben. Arch. Hyg. Bakt. 150, 78. Gilgen, A. & Wanner, H. U. (1966). Die toxikologische und hygienische Bedeutung des Ozons. Archs. Hyg. Bakt. 150, 62.

K