DISINFECTION AFTER VARIOLA MAJOR

587

POLYTETRAFLUOROETHYLENE SIR,-I have had many requests for information about the important fluorocarbon, polytetrafluoroethylene, (C2F4)n,’Fluon’,’Teflon’, commonly known as P.T.F.E.). It is one of the best of a relatively new group of plastics remarkable for their great chemical resistance, excellent dielectric properties, and wide working temperature range. It has a great variety of mechanical and general engineering applications where advantage is taken of its low coefficient of friction (very few substances will adhere to its surface). This quality is one of the properties that has made it useful in the food industry and more recently for surgical applications in this and other countries. Some doubts have been expressed about its suitability for such purposes, mainly because of misleading reports on its possible dangers, which the following facts should help to correct.

unlikely that sufficient polymer is subjected to a high enough temperature to produce enough localised fume for this purpose. Most of the cases previously thought to be due to machining were almost certainly caused by smoking at work 9 or by conhands or clothing with powder subsequently transthe tobacco. Fluon is used as linings for bakers’ roll mills and food containers. The possibility of food contamination was investigated by Coppock and Knight" who showed that the minute amounts of fluorine compounds absorbed were reduced to harmless quantities by heating the containers before use. The use of the polymer dispersion for lining utensils such as frying-pans has more recently been questioned. It was originally proposed for this purpose in France and investigated by Truffert 11 and Troyanowsky.12 They concluded that the polymer was safe for such uses, and millions of utensils have since been manufactured with no reports of any ill effects. The Food and Drug Administration in the United States has stated more recently that the uses of teflon resins whereby they come into contact with food durirg processing or cooking do not present any problems under the Food Additives Amendment, and again large quantities have been sold without apparent harm to the

taminating ferred

to

The polymer is extremely inert and inactive, being unaffected in its normal state by any known solvents except molten alkali metals. It is much more thermostable than other plastics and is used over a temperature range from at least as low as that of liquid nitrogen to over 250°C. The polymer produces no skin irritation or sensitisation and no reaction when implanted in living tissues.1 It is harmless when ingested daily by laboratory animals over a period of months. When heated above 250°C it begins very slowly to decompose giving rise to very small quantities of gaseous products up to 400°C, which are toxic to laboratory animals. Above this temperature the amount of decomposition products increases more rapidly, but is still insufficient to identify accurately all the substances so formed until the temperature reaches 400-500°C.2 A few years ago, the National Advisory Council for Aeronautics in the U.S.A. memorandum3 on the safety regulations for machining teflon mentioned the death of a machinist who had smoked a cigarette contaminated by the polymer. Detailed and intensive investigation by several authorities have shown that the assertion was completely without foundation, but the It was repeated by Mack 4 rumour continues to circulate. but subsequently retracted.5 The United States Air Force issued a strongly worded statement refuting the allegation, and in this country the Minister of Labour stated in the Commons that the Government had no knowledge of such s an incident. Men inhaling the fume develop a characteristic syndrome with influenza-like features, which has been described as "polymer fume fever".The signs and symptoms follow a latent interval of a few hours, are always evanescent, and invariably subside within 24-48 hours with no after-effects. The patient may suffer more than one shivering attack (known appropriately as the shakes ") after a single exposure to the fume. In industry workmen may be accidentally exposed when the polymer is fabricated, for example, by extrusion or by heating in an oven, especially if thermostatic control is at fault as sometimes happens. Adequate control or the intelligent use of exhaust ventilation will prevent this hazard. Workmen are far more often affected by smoking tobacco contaminated with the powder. This is probably the commonest way in which factory workers are affected, and very few particles of the powder on the end of a lighted cigarette are sufficient to produce the illness.8 High-speed machining of the polymer is a doubtful way of producing fume, since it is

DISINFECTION AFTER VARIOLA MAJOR SIR,-It has been demonstrated in the laboratory that crusts which form after inspissation of the smallpox pustule can remain infectious for many months under suitable conditions. Bearing this in mind can we be satisfied that the present methods of disinfection of premises after a case of smallpox are adequate ? In this connection the findings of Epstein et al. 17 are of interest. He reported that bed bugs had become infected with vaccinia when infesting an infected animal and that they retained the property of transmitting the condition for twelve days.

1. Le Veen, H. H., Barberio, J. R. Ann. Surg. 1949, 129, 74. 2. Zapp, J. A., Limperos, G., Brinker, K. C. Paper to American Industrial Hygiene Association, 1955. 3. Reid, H. J. E. National Advisory Council for Aeronautics Memorandum, 1956. 4. Mack, G. J. Canad. med. Ass. J. 1961, 85, 955. 5. Mack, G. J. ibid. p. 1358. 6. Hansard, item 85, May 8, 1958. 7. Harris, D. K. Lancet, 1951, ii, 1008. 8. Sherwood, R. J. Trans. Ass. industr. med. Offr. 1955, 5, 10.

9. Harris, D. K. Brit. J. industr. Med. 1959, 16, 221. 10. Coppock, J. B. M., Knight, R. A. Brit. med. J. 1957, ii, 355. 11. Truffert, L. Ann. Falsifications et Fraudes, 1958, 51, 319. 12. Troyanowsky, C. Arch. Mal. prof. 1959, 20, 57. 13. Pitts, F. W. Proc. Soc. exp. Biol., N.Y. 1954, 85, 404. 14. Quereau, J. V. D., Souders, B. F. A.M.A. Arch. Ophthal. 1956, 55, 685. 15. Charnley, J. Brit. med. J. 1960, i, 821. 16. Brit. med. J. March 3, 1962, p. 612. 17. Epstein, G. V., Morozov, M. A., Exemplarskaya, E. V. G. Batt. Immun. 1936, 17, 475.

·

"

users.

The plastic had been used surgically with encouraging results-e.g., as a draining material,13 as an orbital implant,14 and more recently in reconstructive surgery of the hip-joint.15 It has been subjected to a more thorough investigation than many comparable materials, and the facts suggest that its hazards have been misinterpreted and exaggerated. Chemical Industries Ltd., Plastics Division, Welwyn Garden City, Herts.

Imperial

D. KENWIN HARRIS.

SMALLPOX

SIR,-Iwas delighted to see Sir Leonard Rogers’ demand (March 3) that acceptable certificates of recent vaccination be required of all entrants to this country, but I would further point out that the present form of international certificate is quite useless as a protection, because it does not require inspection of revaccination. It must by now be generally realised that a number of revaccinations fail to take at the first attempt but that second attempts often reveal a very low state of immunity. It seems likely from the report of Dr. John Douglas and Dr. William Edgar 16 that the Bradford epidemic can be attributed to this very fallacy in the international certificate. It seems clear from Sir Leonard’s remarks that unless this situation is rapidly remedied at international level outbreaks will continue to occur in this country. S. CLIFFORD ROGERS. Rugby.

588

It seems possible, therefore, that bed bugs in a house infected with smallpox may be capable of transmitting the disease and may well escape the ordinary routine measures of disinfection. County Hall, Newport, Wight.

JOHN MILLS

Isle of

Medical Officer of Health.

TREATMENT OF FEMALE CYSTITIS to congratulate Mr. Bennett-Jones his excellent article of Feb. 10. It very necessarily brings notice to the existence of bladder-neck infection and obstruction in women-a condition not yet fully

SIR,-I should like

on

recognised. Having been St. Paul’s

one of Mr. Winsbury-White’s registrars at Hospital, London, I am very interested in this

---

I that

subiect.

..

agree

these patients, unless in an acute

attack,

usually have

Fig. 1-Relation of increased frequency to urine in 165

women.

sterile urines (fig. 1). The patients’ main complaint, between attacks of acute cystitis, is increased frequency of micturition. The irritation and urgency sterile are caused by infection lurking in the glands of the proximal1 urethra, with

surrounding hyperaemia of the trigone and the formation

I agree that urethral dilatation can produce dramatic results, and that it can be used diagnostically, as can the dilatation of cystoscopy. The cures resulting from a single dilatation are in early cases before the condition becomes chronic. The dilatation opens the orifices of these glands and allows free drainage-a basic principle in surgery of inflammation. I suggest the following sequence of events. Firstly, the glands of the posterior urethra become infected. If this is not treated the infection becomes chronic. This leads to upset of the sphincter mechanism and later to fibrosis and bladderneck obstruction. I would add that there may well be residual urine before there is true organic obstruction. The cases with fibrosis and true organic obstruction undoubtedly need perurethral resection. It seems unnecessary, however, to use the more major procedure of resection, no matter how expertly performed, when the minor procedure of fulguration will relieve most patients. Fulguration of the bladder-neck with a weak diathermy current does not upset the patients at all and there are no dangers. This leaves resection for the small resistant group, usually patients with longstanding infection, fibrosis, and true organic obstruction. The data in figs. 1 and 2 are taken from a survey described in paper read to the East Midlands Surgical Society. Doncaster.

a

W. MCCAUSLAND SCOTT.

BOXING Sherriff’s SIR,-Dr. arguments not do.

(March 10) simply will

Amateur boxers, certainly small boys, do not box with the deliberate object of producing cerebral concussion or other bodily damage. They box to score points. When they fight in the playground with bare fists their motives may be less pure and the results more traumatic. In any event, what is the point of trying to discriminate between deliberate and accidental trauma ? In rugby football, where trauma is presumed to be accidental, concussion is not uncommon and a broken neck not unknown. Would Dr. Sherriff also ban rugby football ? The comparison between boxing with gloves and gladiatorial combats with cesti can hardlv be taken seriouslv. Crediton, L. N.

JACKSON.

Devon.

of granulomata

and

pseudo-polyps at the

bladder-

neck. Every so

often

the infection bursts forth Fig. 2-Relation of erosion of cervix to increased from these frequency in 165 women. glands, freauentiv after intercourse, causing an acute attack of cystitis and even pyelitis. The urine then shows infection. The size of some of the polyps can only be fully seen with a Swift-Joly posterior urethroscope. The resectoscope or to their full extent. does not show them up panendoscope Mr. Bennett-Jones rightly emphasises the importance of pelvic infection and pelvic operations in this condition, but he belittles the part played by the eroded cervix. Mr. Winsbury-White showed experimentally that, when Indian ink was injected into the cervices of guineapigs, particles of this ink could be demonstrated around the bladderneck and even extended up to the kidney via the periureteric

lymphatics. 2 shows the relation of eroded cervix to increased in females from the age of 6 onwards. Unless the cervical and vaginal infection is cured it is useless to treat the bladder-neck. In fact in young women this is often all that is necessary.

Fig.

frequency

1.

Winsbury-White,

H. P. Brit. J. Urol.

1933, 5,

249.

LOW INCIDENCE OF MYOCARDIAL INFARCTION IN HEPATIC CIRRHOSIS

SiR,—It is certainly possible that a change in the oestrogen-androgen ratio may protect patients with hepatic cirrhosis against myocardial infarction, as suggested by Dr. Ivanyi (Feb. 24). It has also been speculated that the diet of alcoholics lacks atherogenic substances or that the

alcoholic liver

cannot

manufacture

cholesterol.1 Raaschou (personal communication) has suggested that the low incidence of myocardial infarction among this group of patients may be related to the infrequency of hypertension in patients with liver disease 2 3. In our paper 4 we merely wished to point out that the high mortality of cirrhosis alone could produce a decrease in the incidence of myocardial infarction at necropsy of the magnitude observed by ourselves and previous investigators. It is hard for retrospective necropsy studies to prove a negative correlation between two diseases. Prospective clinical investigations or experimental work seem much better adapted to the solution of this interesting problem.

BORIS H. RUEBNER Department of Pathology, K. MIYAI Johns Hopkins Hospital, HELEN ABBEY. Baltimore, Maryland. 1. Nutr. Rev. 1961, 19, 37. 2. Raaschou, F. Circulation, 1954, 10, 511. 3. Loyke, H. F., Cutarelli, R. Amer. J. med. Sci. 1960, 240, 346. 4. Lancet, 1961, ii, 1435.