1104

SERUM-VITAMIN-B12 AND CHLORPROMAZINE

E. EDWINK. HOLTENK. R. NORUMA. SCHRUMPFO. E. SKAUG.

St. Joseph’s Hospital,Porsgrunn, Norway.

SIR,-Dr. Herbert (March 5), in criticising our determina-tions of serum-vitamin-B12 levels in patients before and afterchlorpromazine therapy, suggests " that before the secondvitamin-B12 determination the patients had been off largedoses of chlorpromazine for a week ". Chlorpromazine treat-ment was not stopped before the second assay. We have alsostudied patients treated with high doses of chlorpromazine foryears. Their serum-vitamin-B12 values were not low.We have established with reasonable certainty that chlor-

promazine in usual doses does not inhibit the growth ofEuglena alga. Nor does chlorpromazine suppress the

growth of Lactobacillus leichmannii, as shown by Dr. Forshawand Miss Harwood (March 12).

Dr. Herbert implies that our patients were inadequatelyexamined, and states that we did not find structural hsemato-poietic damage in a single case. He could easily have seenfrom our original paper 1 how many of our patients with lowvitamin-B12 values had hypersegmentation, anisocytosis, andglossitis, and changes of Hb, erythrocyte-sedimentation rate,mean corpuscular haemoglobin, red-cell count, serum-iron,gastric juice, Schilling test, bone-marrow, and neurologicalstatus. Good correlation was found with the Schilling test,and some of the other tests were also positive. The vitamin-B12assay, however, was the only test which allowed us to pick outthese patients immediately.

TETRACYCLINES AND THE TEETH

J. D. MANSON.

Royal Dental Hospital of LondonSchool of Dental Surgery,University of London,

London W.C.2.

SiR,—The fact that discoloration of teeth can result fromtetracycline medication during the period of crown formationhas now been widely reported, and as your leading article(April 23) points out this fact should be borne in mind whenchoosing an antibiotic for children up to about 7 years old.Nevertheless it seems important to maintain a sense of pro-portion in this matter and not to prejudice the practitioneragainst these drugs unjustifiably.During the past 4 years I have used tetracyclines as a bone-

label in the study of bone activity and growth in animals. Thelevel of medication has been similar to that of the 4-5-daytherapeutic human adult dose and at this level there have beenlittle if any macroscopic signs of pigmentation, although thelabel is clearly visible in sections of enamel and dentine whenviewed under ultraviolet light. It seems that the occasionaluse of tetracycline for acute illness in the child is most unlikelyto produce obvious discoloration of the teeth. When the needexists for more prolonged or frequent medication the advan-tages of using tetracycline may be so great as to outweigh thedisadvantage of slight tooth pigmentation, and in the moreextreme cases it should be borne in mind that teeth can becrowned effectively if necessary.

SANS TEETH, SANS EYES, SANS TASTE

SIR,-In your annotation (March 19) you refer to the prob-lem of labelling dentures for patients in hospital. As Dr. Finepoints out (April 9), a denture can easily be marked identifiablywhen it is being made, and I know of at least 16 methods,although tattooing had not occurred to me. In 30 minutes adental technician could put a name permanently on any " old

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denture in one of at least 10 different ways. For the especiallyfastidious, the name can be written in invisible ink on pinkpaper; this is processed into a recess in the denture, and only1. Edwin, E., Holten, K., Norum, K. R., Schrumpf, A., Skaug, O. E.

Acta med. scand. 1965, 177, 689.

shows under ultraviolet light. A simple method is now beingtried which a nurse in a ward can carry out in less than 5minutes; the denture can be returned to the patient in about anhour, and remains identifiable for months.

This subject is being discussed at the Fourth Internationalmeeting in Forensic Medicine in Copenhagen and at the Con-gress of the Federation Dentaire Internationale at Tel Aviv inthe summer.

WARREN HARVEYUniversity Dental Hospital

and School,Glasgow C.3.

FLUORIDATION AND THE COUNCILLORS

WINIFRED M. SYKESHon. secretary,

National Pure Water Association.

SIR,-In his letter (April 30) Dr. Dalzell-Ward admits thatthe general practice is to limit the permitted amount of foodadditives or pesticides to 1 % of the maximum no-effects levelas ascertained by animal experiments. The maximum no-effects level is naturally somewhat less than the minimum chronictoxic dose. So far we agree. He insinuates, however, that somedifferent rule is applicable when the maximum no-effects levelis known for human beings. Will he tell us what that rule is? Until he does so, his argument lacks any factual basis.

Dr. Dalzell-Ward then proceeds to suggest that the normalpractice should be ignored, because inorganic fluorides are

found in water and food. He must know very well that the

quantities of fluoride found in foods differ greatly between onefood and another. Even in the same kind of food there may be

great variations. For example, the dry tea-leaf may containfrom a few to several hundred parts per million of fluorine. Itfollows therefore that the intake of fluorine may vary greatlybetween one individual and another, and this is a further reasonfor exercising the greatest caution with regard to proposals forcompulsorily increasing the intake of fluorine.

Incidentally Dr. Dalzell-Ward implies that the fluoridesfound in foods are inorganic and are the same as the sodiumfluoride and sodium silicofluoride used in water fluoridation.

Perhaps he will refer your readers to the scientific evidence forthis. It is certainly not true in all cases, if it is in any.

In the case I referred to 1 it may be true that the proximatecause of death was pneumonia, but Dr. Dalzell-Ward will knowvery well that terminal pneumonia is the end-result of manychronic diseases, and that this does not displace the observationthat the patient was suffering from fluorosis.

THE PRESS AND CRIMES OF VIOLENCE

SIR,-A causal relation between detailed reporting ofviolent crimes and the incidence of similar offences remains tobe demonstrated. Dr. Richard Fox’s arguments, thoughplausible and interesting, might possibly prove non sequitur.Moreover, would the proposed reforms outlined in yourannotation (April 30) be sufficient ? Surely many current tele-vision plays and thousands of paperbacks would be next on thelist for censorship, and who knows what further incursionsinto public liberty might then be introduced.The effect of reporting the current moors murder trial in

detail remains to be seen, but I do not recall that the wide-

spread publicity afforded to the Christie murders at the timeresulted in further perpetuation of that particular type of horriblecrime. Indeed, partial or complete censorship might easilyhave the opposite effect, thereby stimulating a morbid thirstfor knowledge on the part of some persons resulting in dis-tortion and misinterpretation of any information made avail-able for public consumption. Nothing dispels suspicion andignorance more effectively than good communications.

I am opposed to anything prejudicial. o relations between theprofession and the Press which might result from restrictive

1. Sauerbraun, B. J. L., Ryan, C. M., Shaw, J. F. Ann. intern. Med. 1965,63, 1074.