1047

(for which other diagnostic labels would be more appropriate). The inflammatory lesions begin as a follicula]staphylococcal infection, which may lead to abscesfformation, cellulitis, or lymphadenitis. These infection,

respond well to chemotherapy ; disability is brief, ancreturn to full work at the coal face rapid. The pressurelesions are associated with effusions into bursae, usually irfront of the knee. Roantree finds that such lesions mabe compatible with full efficiency-indeed, few coal-factworkers have normal knees. It is the increase in size ojthe bursa, accompanied by pain, which makes worlidifficult or impossible, and at this stage the bursa containsblood. Aspiration is of value in the treatment of theselesions, provided the skin is clean and the bursa does notcommunicate with the knee-joint. Rest from kneeling Ü

important, and must often be protracted. Surgicalexcision of the bursa involves a long period of disability,and many miners cannot return to the coal-face aftei

operation.

1. Whitehead, T. P. Lancet, Nov. 9, 1957, p. 953.2. Bradford Hill, A., Lewis Faning, E. Brit. J. industr. Med. 1948,

5, 1.3. Birmingham Post, Nov. 12, 1957.

ARSENIC AND POTATOES

THE spraying of crops with toxic chemicals is nowcommon practice on most farms in this country. Thechemicals are used mainly as weed-killers and insecticidesand their application is controlled by regulations definedin law. The aim of all concerned-research-workers,chemical manufacturers, and Government administrators-is the production of non-toxic substances which will beequally effective but safe both to spray-operators andconsumers. There is now disquieting evidence, however,that potato crops are being widely sprayed with sodiumand potassium arsenite in place of the sulphuric acidhitherto used to achieve rapid destruction of the potatotops (haulms).

Sulphuric acid has been used for many years as adefoliant of potato crops. The haulms are destroyedrapidly and the tubers can be spun out of the ground bya machine without the bulky haulms getting in the way :the crop is then gathered by hand. The replacement ofsulphuric acid by sodium and potassium arsenite spraysseems a retrograde step. These arsenite sprays are notmore efficient as defoliants, but they are easier to handlebecause they do not corrode the metal parts of machineryor burn clothing. The worst that can happen to spray-operators or crop-pickers after sulphuric-acid sprayingare superficial acid burns. Arsenites, on the other hand,are extremely toxic substances. Acute arsenic poisoningis possible, and arsenites are also a potent cause ofdermatitis. Furthermore, Bradford Hill and Faning 2showed in 1948 that the mortality from cancer amongfactory-workers exposed to arsenite dust was significantlygreater than that found in three other occupationalgroups living in the same area. Both the spray-operatorsand the crop-pickers are liable to exposure. As White-head 1 points out, potato pickers are often women whotake their children into the fields with them, and thechildren play there while the mothers work. Sandwichmeals are often eaten in the fields, and there is no pro-vision for washing.The possible hazard to the consumer is slight, but it

should not be neglected. The public analyst of Coventryis reported 3 to have found sodium arsenite in the skinsof five out of seven samples of potatoes examined ;and his advice is to peel all potatoes before cooking them.(Two of the samples came from the Warwick area,where W’hitehead 1 has investigated four operators whohad been spraying arsenite ; three showed excessiveexcretion of arsenic in the urine and one had vomitingand diarrhoea.) Certainly the contamination of potatoeswith small quantities of a known poison has little tocommend it. Obviously, the residue of arsenic on potatoes,

expressed as parts per million, could be misleading, sinceso many more potatoes are consumed than, for example,soft fruit, such as strawberries. If the practice of sprayingpotato crops with arsenicals immediately before harvest-ing is to continue, then stringent regulations for their useshould be instituted and enforced ; but the replacementof arsenical sprays by less dangerous substances seemsa much wiser course.

1. Haldane, J. S., Priestley, J. G. Respiration ; p. 204. Oxford, 1935.2. Westlake, E. K., Simpson, T., Kaye, M. Quart. J. Med. 1955, 24,

155.3. Sieker, H. O., Hickam, J. B. Medicine, 1956, 35, 389.4. Simpson, T. Lancet, July 20, 1957, p. 105.5. Austen, F. K., Carmichael, M. W., Adams, R. D. New Engl. J.

Med. 1957, 257, 579.6. McMichael, J., Lennox, B. Lancet, 1949, ii, 1057.7. Simpson, T. Brit. med. J. 1954, i, 297.8. Kety, S., Schmidt, C. F. J. clin. Invest. 1948, 27, 484.9. Patterson, J. L., Heyman, A., Duke, T. W. Amer. J. Med. 1952,

12, 382.

NEUROLOGICAL DISTURBANCES IN PULMONARYINSUFFICIENCY

NERVOUS tissue is more vulnerable than any other tometabolic disturbances. In the words of Haldane and

Priestley 1:" With severe and prolonged exposure to want of oxygen

the nervous after-symptoms are of an extremely formidablenature, and often end in death ... the patient does notrecover at once on removal of the oxygen want, as in shortexposures."

In respiratory failure, anoxia is associated with carbon-dioxide intoxication ; and the neurological disorder maydominate the clinical picture. 2-4 Austen et all havedescribed three patients with lung and heart failure whohad been thought to have brain tumours on account ofheadache, papillcedema, confusion, and twitches ; and afourth without papillcedema but with a striking disorderof movement that had been presumed to be myoclonus.In each case there was anoxaemia, hypercapnia, acidosis,and heart-failure due to inadequate alveolar ventilation,complicating long-standing lung disease. When thealveolar under-ventilation and its metabolic compli-cations were corrected the neurological manifestationsdisappeared.For months all four patients had been drowsy, irritable,

and confused ; and on admission they were breathless andcyanosed. Two of them vomited. All had steady intense head-ache-frontal, occipital, or general-worse at night and in theearly morning. In the three patients with papillcedema thecerebrospinal-fluid (c.s.F.) pressure was greatly raised.Electromyography showed momentary interruption of the

normally continuous action-potentials. This, together with thefreedom from twitching during rest, distinguished the musculardisturbance from myoclonus.

Papillcedema is rare in pulmonary heart-disease, whereit must result from the coincidence of congestive heart-failure, hypoxia, hypercapnia, acidosis, and increasedC.S.F. pressure. Hypoxia and hypercapnia cause cerebralaedema.67 1 Hypercapnia and acidosis cause cerebralvasodilatation and allow an increase in cerebral blood-flow.s The resulting increase in filtration pressure acrossthe choroid plexus leads to an increase in c.s.F. pressure.9A rise in venous pressure alone also raises the c.s.F.

pressure but does not cause papilloedema—e.g., in patientswith superior mediastinal obstruction. Chronic hypoxiaby itself may not greatly disturb consciousness, butmay make the nervous system more sensitive to othermetabolic changes.

In the treatment of anoxic cor pulmonale with oxygenthe physician tries to dispel the delayed effects ofanoxaemia without inducing undesirable immediateeffects of increasing respiratory acidosis. Three of Austenet al.’s patients were given oxygen ; and all three becameunconscious when the arterial carbon-dioxide tensionrose, though anoxia had been corrected. The rate ofoxvsen administration should be controlled by the state