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TaE L',NCET. DECE.SIBER 3:1983 The risk ratios for passivc smoking can be surprtsinih• high(up to 2 or 3); as reponed~both b+• Corrra et al and othas. '° Tbese risk ratios would be morc consistent t.ith those found for active amoking, panicularlv among women, if the acttve smoker is at groter risk also from his or, her own passive smoke, again through the absorption of radioactivttt• on the smoke particles passivelt• inhaled; also the relattvel v higher toxiaty ofthe sidcstream strwkelh' might be iinportant.l l These and other aspects (eg, the urbut-rurali difference in lung czncer, rrisk from smoking) are more thoroughly discussed elsewherel' in the context of indoor radon daughters. Finally, in view of the long latrncv periods observed'among mirters acquiring lung cancer from radon daughter exposure, I t one might suggest that the chililrctt of smoking mothen obtain an early exposure to increased levels of radon daughters at home andahu smoking Later in life promotes the developtrxat of luag cancer. Dq.enena arcktvy.r,w./ MsdK.K. t3...er... Heeo,od, ~ SStl1. tIS L.keo.+µ, S.edrn OLAC. /,l_YELiON LUNG CANCER AND PASSIVE SMOKING St1t,-l was surprised to-read, in Professor?sidtopouioa and colleagues' lener (Sept 17, p 6/), a German study of ptssive smokiag and lung esrtccr desaibed as having yielded "positive" results. 3be paper ated' contains onlv tentativtr mttdusioes 6sed ilo poor data analysed bv unacceptable atethods. I was also surprised that the findings from the Greek hospital study of passive smokingand'lung cancer were almost idential!to those reported two years ago= despite a substantial inaease in the numbers of cases and controls. In the 1981 report the relative risks of lung ancer-for, tton-smoking women were 1,, I•8, 2•4, and 3•4 according to whether their husbands di& not smoke, were ex- stttokers, or were eurreat srnoken of 1-20 or 21 or more tigarettes a dar, the updated relative risks are 1, 1• 9, 2• 4, and 3• 4, respeaivel•v. In the 1981 paper the relative risks agreed exactly with the appropriate ams-product ratios cnlculated' from the numbers of cases and controls in the relevant cstegory for husbands' smoking. In the latest results, despite the method being apparcntlv identical, there is a clear disagreemcnt between the relative risks ptvvided by Trichopoulos et al and those I caleulatr(see tablej; Rfl.1TtVE R1SK OF Lt7NG CkJvCFJt ACCORDINGTO SMOKING HAIITSOF HtalA.D I eiprnus perr dsr i (tvrrrnt smolicni Cmiup t:wisn#ers Ea•s.nokcn 1-211 21+ 1tRtquaed) 1•0 1•9. 2•4 i S•4 RR4qkvliced)~ 1•0, 1•9. 1•9 2'6 aiW.wr r»l ~ rxm ai r.J - M,[ mn anu~ne ...mrn .-M.. Aussa.A OrMnK rs a FM~KY/if fTO~a,( CatK'f V,~ M„1u1. J/Mn[w.MIK'/F Ynv1Y' 11Y.141,J•' >t.1Y~Y~111Vtr~. Mr ealeulattotu suggest that the iatestdata do not show as clear an 'koodanon bcrweea a womati s lung cancer risk with her tiusband's letoking habits as the earlier data did. Indeed, relative risks calculated from the additional data are 1, 2• II, l' 8, and I•$ and do a.or trhow the dose-raponse teiatnn som earlier. This doubt, added a H.re.anyT \m..,rlwr.,.nefAea...uma- tu.celqMnatefleycrcca vwf. nan J*WS s.Mel j 19s1:31b lt/J-9S•. Tncenpwlp D. Ka1e.0.dt,A..Sp.rree L Mec.MsAw 1 t.aurt wor as0 ranw .wr.unr. lr 1 Gnm 198g:SJ: 1-a. 10. Surf.on Gs.nrni Tbr isalr! esa.rp- uf aawatnr' Caecet. Yedn.poe. DC. L'S Dsp af H.abL Eeuwme anA 1<elfars. 191:; DHHS IPHS)12-50179. 11:.Ax,aL.. raureamoa,nRand)uaq:,nra.L~nl9t::t: )01a-!s. I:.A.daen,U' Roemiware4farradso.~lu+ytanrwouaa.e~a.t4Jflrr.•~twpreu): J3: Mrlaowt).Saa411L 11..wR.,lreecanenaedareeaane.Suiw/)tr.AE~,mwn:H:~hk 1973. 4: a6- S.'. t:.Gmmh A. BoMn Ii., SclmnpttF Paoaiauctxn al. Lun/cnkRbtwttiAc(K, \~l+„aocAcr,nncn...tLJiil,r P.u 1963. re:Sl-ia ;.~ Tnchqoula D. IGIsndWi k. Spar.w l. .lta. \talwn t/. Lune :~m . mA tqawz .vwa.ne 1:, 7 G,n.,. )att:27: !-4 ' 1309 ,pge doubts nbout the histological evidence and the tae of ases and ~tangrols from dilTerent hospitals (limltarions which Trichopouios et; a) 'concede); prompts one to ask if the stud}• really does add to the avideact: impliating passtve smoking as a factor in ltmg amcxr. l.'e,~ersp. ef I:.rprWte: DDTSC01'.rtarrh.l.VaGme.a~ WULF-D117F]l FIEU.Ek POTASSIUM 43LOR]DE SUPPLEMFNTS S)ta; As your Round the World correspondent prediaed,l the US Food and Drug Administration advisory comnuttee maeting of vvstts March 2 at the controversy of wax-matrix microencapsulated potauium- chloride preparations proved inwndusive. A few points about this controversy are woeh noting:. The study by McMahon et al,= showing a favottnzble result for 'Micro•K' (A'H. Robins) in comparison with 'Slow-K' (Ciba- Geigy) was sponsored by Robins. The study b,v Patterson et al,s showing no difkrence between micro-K and slow-K, wasspottsored by Ciba-Geigry. Both studies have becn confirnsed:b,v other srudies sponsored by the respective company. Ciba-Geigy, while denying that slow-K is more ularogenic than miao-K, has bought from Alfred Benzon Ltd, Denmark, a licence for 'I:alinorm', a micoennpsulated (pellet) preparation of KCt similar (or identical) to miao-K. It seems remarkable tlsat Gb/} Geigy is planning to muket this preparation when, according to Ciba-Ge'tgy,'s US subsidiary, "Slow-K has an established clinivll record unparallded-by any othersolid'K supplemeat". It seerm that, privately, Ciba-Geigy has concluded that kalinorm is as good as asiero-K, and that it is better than slow-K, but they would-presumably consider it scienrifically incorrecT to conclude that micro-K is better than slow-K. Finally I would etnphasise, as your R-IT conapondtmrdid, that doctors should "re-evaluatc the decisive need for a potassium supplement and, ifthe indication is clear, prescribe it as a liquid". The findings of Patterson et as t clearly support this. fiAra BEtcAU. FwWwfse .7. S4T1N PanJk.S..een Ota.E Hmmsot. '.*This letter has been shown to Dr Burk,v„ whose reply follows.-Eo. L S1R,-One of the main reasons why slow-releasc formulations of potassium were developed was the unacceptability of liquid potassium. Indeed, Patterson ci a11 reported that KCP elixir was poorly tolerated in their, trial, giving rise to abdominal'pain and heartburn in 9 of the 15 volunteers (60%). Dr Hansson omits to mention this.'17te nwe is therefore whether the riskJbenefit ratioof 'Slow IC' is acceptable. There are eighteen vears of clinical experience w•ith slow K in the UK, during which over 4- S million patien!-yqn of vcattncnt has been prescribed: with 'Miero' S:' formulatlons there is almost no clinical experience. Las than 50 ases ofsigmficnt alimentarg side-eRects have been reported with slor• K, and some of thcse werc tnanifestlv brought about by^ previous strictures or oesophagcal obstruction due to cardiac enlargement. lt would be hard to point to a comparable safety record with any other videly, used drug.,Thc faa: that a company rmy be investigating or pursuing alternatives is an indiot/on ofincerest and involvement in the area, and should'not be interpreted as a Itxs of confidence in an enisting product. C,G.G.ryI. rt~rnrn,w,o4... Hwaeam. t'nr Sw.e I)E\tS Bt'lltfl" I. .inon, rarnwrm wyplt~r.enn and.upp~r raueowearmat enn. L.+n19it: r: aw li. Il nm JR. E.ran A. l'prpc* Faurannraeuul 1l.wm afio. paaauum. eAl6rdr .u00kmMn: s cennolued :1m.Ntna7.' La.me.. I W2: u I6S9-e1 S Panmon D1.K'i.e+~~ C~ icRrns f:H..Endexeqccompa.nen of whd antl I,pwd. ppaaum etibede supp+emenra L..n,a 19tlS. ,.. 10T. ~-:a