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Is daar 'n wetenskaplike bewys dat rook die vel van die gesig bederf?

Is daar 'n wetenskaplike bewys dat rook die vel van die gesig bederf?


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Ek het gesien dat sigarette-rokers (meer as 3 sigarette per dag) dikwels die vel van die gesig het wat 'n bietjie bederf is.

Is daar enige wetenskaplike bewys dat sigaretrook (of die nikotien daarin) 'n skadelike faktor vir gesigvel is?

Of is dit net as gevolg van die vel-rook-interaksie wat deur die rook veroorsaak word dat die persoon uit die mond uitasem?


Hierdie bladsy is redelik volledig met voorbeelde en verwysings.

Samevattend is baie van die bewyse empiries – jy kyk na rokers en die kwaliteit van hul vel en vergelyk met nie-rokers en die verskille is statisties betekenisvol en reproduseerbaar. Dit wil voorkom asof dit ou werk is wat uit die 1970's dateer.

Dit is dus in baie gevalle slegs waargenome korrelasies. Maar daar word redelik sterk saamgestem deur mediese mense. Gegewe die feit dat ons steeds nie presies weet wat kanker veroorsaak nie, dink ek dit is nie 'n ongewone vlak van verduideliking vir mediese toestande nie.

Soos jy kan sien, sal sommige teorieë direkte effekte van die rook en sommige indirekte effekte insluit.

Dit is nie seker presies hoe rook vroeë veroudering van die gesigvel veroorsaak nie. Teorieë sluit in:

  • Hitte van die sigaret wat die vel direk verbrand
  • Veranderinge in die elastiese vesels van die vel
  • Vernouing van bloedvate (vasokonstriksie), wat bloedtoevoer na die vel verminder en veranderinge in vel elastiese vesels en verlies aan kollageen kan veroorsaak
  • Verminder vitamien A-vlakke en vog van die vel

Hoe rook vroeë veroudering en voortydige plooie veroorsaak

Sharon Basaraba is 'n bekroonde verslaggewer en senior wetenskaplike kommunikasie-adviseur vir Alberta Health Services in Alberta, Kanada.

Armeen Poor, besturende direkteur, is 'n raad-gesertifiseerde pulmonoloog en intensief. Hy spesialiseer in pulmonale gesondheid, kritieke sorg en slaapmedisyne.

Gilbert Laurie / Getty Images

Rook beïnvloed amper elke orgaan van jou liggaam negatief, en dit sluit die grootste orgaan in: jou vel. Sigaretrook bevat gifstowwe wat die kwaliteit van jou vel beïnvloed, wat lei tot plooie, voortydige veroudering en moontlik selfs veltoestande.

Om bewus te word van die uitwerking wat rook op die vel het, is belangrik, en dit kan selfs help om jou te motiveer om op te hou rook.


Algemene wanopvattings oor Wetenskap I: "Wetenskaplike bewys"

Wanopvattings oor die aard en beoefening van wetenskap is volop en word soms selfs deur andersins gerespekteerde praktiserende wetenskaplikes self gehuldig. Ek het sommige van hulle (wanopvattings, nie wetenskaplikes nie) in vroeëre plasings uit die weg geruim (byvoorbeeld dat skoonheid in die oog van die aanskouer is, skoonheid is net vel diep, en jy kan nie 'n boek aan sy omslag beoordeel nie).

Ongelukkig is daar baie ander wanopvattings oor wetenskap. Een van die mees algemene wanopvattings het te make met die sogenaamde “wetenskaplike bewyse”. In teenstelling met die algemene opvatting, is daar nie iets soos 'n wetenskaplike bewys nie.

Bewyse bestaan ​​slegs in wiskunde en logika, nie in wetenskap nie. Wiskunde en logika is beide geslote, selfstandige stelsels van proposisies, terwyl wetenskap empiries is en handel oor die natuur soos dit bestaan. Die primêre kriterium en standaard van evaluering van wetenskaplike teorie is bewyse, nie bewys nie. Alles anders gelyk (soos interne logiese konsekwentheid en spaarsaamheid), verkies wetenskaplikes teorieë waarvoor daar meer en beter bewyse is bo teorieë waarvoor daar minder en slegter bewyse is. Bewyse is nie die geldeenheid van wetenskap nie.

Bewyse het twee kenmerke wat nie in die wetenskap bestaan ​​nie: Hulle is finaal, en hulle is binêre. Sodra 'n stelling bewys is, sal dit vir ewig waar wees en daar sal niks in die toekoms wees wat sy status as 'n bewese stelling sal bedreig nie (tensy 'n fout in die bewys ontdek word). Afgesien van die ontdekking van 'n fout, sal 'n bewese stelling vir ewig en altyd 'n bewese stelling wees.

Daarteenoor is alle wetenskaplike kennis voorlopig en voorlopige, en niks is finaal nie. Daar is nie iets soos finale bewese kennis in die wetenskap nie. Die tans aanvaarde teorie van 'n verskynsel is eenvoudig die beste verklaring daarvoor onder alle beskikbare alternatiewe. Die status daarvan as die aanvaarde teorie is afhanklik van watter ander teorieë beskikbaar is en kan môre skielik verander as daar 'n beter teorie of nuwe bewyse verskyn wat die aanvaarde teorie kan uitdaag. Geen kennis of teorie (wat wetenskaplike kennis vergestalt) is finaal nie. Dit, terloops, is hoekom wetenskap soveel pret is.

Verder, bewyse, soos swangerskap, is binêr 'n wiskundige stelling word óf bewys (in welke geval dit 'n stelling word) óf nie (in welke geval, dit bly 'n vermoede totdat dit bewys is). Daar is niks tussenin nie. 'n Stelling kan nie soort van bewys of amper bewys word nie. Dit is dieselfde as onbewese.

Daarteenoor is daar nie so 'n binêre evaluering van wetenskaplike teorieë nie. Wetenskaplike teorieë is nie absoluut onwaar of absoluut waar nie. Hulle is altyd iewers tussenin. Sommige teorieë is beter, meer geloofwaardig en meer aanvaar as ander. Daar is altyd meer, meer geloofwaardige en beter bewyse vir sommige teorieë as ander. Dit is 'n kwessie van min of meer, nie óf/of nie. Eksperimentele bewyse is byvoorbeeld beter en meer geloofwaardig as korrelasiebewyse, maar selfs eersgenoemde kan nie 'n teorie bewys nie, dit verskaf net baie sterk bewyse vir die teorie en teen sy alternatiewe.

Die wete dat daar nie iets soos 'n wetenskaplike bewys is nie, behoort jou 'n baie maklike manier te gee om regte wetenskaplikes van hacks en wannabes te vertel. Regte wetenskaplikes gebruik nooit die woorde "wetenskaplike bewyse" nie, want hulle weet nie so iets bestaan ​​nie. Enigeen wat die woorde "bewys", "bewys" en "bewys" in hul bespreking van wetenskap gebruik, is nie 'n ware wetenskaplike nie.

Die kreasioniste en ander kritici van evolusie is absoluut korrek wanneer hulle daarop wys dat evolusie "net 'n teorie" is en dit nie "bewys" is nie. Wat hulle nalaat om te noem, is dit alles in die wetenskap is net 'n teorie en word nooit bewys nie. Anders as die Priemgetalstelling, wat absoluut en vir altyd waar sal wees, is dit steeds moontlik, al is dit baie, baie, baie, baie, baie onwaarskynlik, dat die teorie van evolusie deur natuurlike en seksuele seleksie eendag vals kan blyk te wees. Maar dan weer, dit is ook moontlik, al is dit baie, baie, baie, baie, baie onwaarskynlik dat ape môre uit my gat sal vlieg. Na my oordeel is beide gebeure omtrent ewe waarskynlik.


Soos wat state begin het om dagga te wettig, is die gebruik daarvan meer openlik bespreek. Terwyl die uitwerking van ander algemeen gebruikte dwelms, soos alkohol, omvattend bestudeer is, is die uitwerking van dagga – veral op ontwikkelende babas tydens swangerskap – baie minder bestudeer en minder wyd bekend gemaak. Hierdie relatiewe stilswye van die wetenskaplike gemeenskap het die publiek se opinie oor die veiligheid van dagga beïnvloed: 70 persent van Amerikaanse vroue dink daar is "geringe of geen risiko van skade" vir die baba as gevolg van die gebruik van dagga tydens swangerskap. Verwagtende moeders kan dagga eerder as voorskrifmedisyne tydens swangerskap gebruik om pyn te verlig, want hulle voel "natuurlik" of boererate is 'n veiliger opsie as voorskrifmedisyne. Net omdat iets "natuurlik" is, beteken dit egter nie dat dit 'n veiliger of 'n beter alternatief vir goed bestudeerde voorskrifmedisyne is nie. Dit blyk die geval te wees vir dagga. Aangesien dagga die mees gebruikte verbode middel tydens swangerskap is, is dit belangrik om die risiko's en impak daarvan op die ontwikkelende fetus te verstaan.

Drie grootskaalse longitudinale studies het nagegaan hoe moederlike cannabisgebruik hul kind se ontwikkeling beïnvloed het, en hulle het verbasend konsekwente resultate gehad. Die Ottawa Voorgeboortelike Voornemende Studie het 700 swanger vroue wat dagga gebruik het in 1978 ondervra en het ongeveer 200 van daardie kinders tot volwassenheid gevolg. Die VSA-gebaseerde studie oor moedergesondheidspraktyke en kinderontwikkeling het 580 kinders van daggagebruikers van swangerskap tot ouderdom 14 bestudeer. Die Generation R-studie volg byna 8 000 kinders in Nederland.

Kinders van daggagebruikers was meer impulsief en hiperaktief, en het gedragskwessies, laer IK-tellings en geheueprobleme getoon in vergelyking met kinders van nie-gebruikers. Hierdie geestesgesondheidsprobleme het voortgeduur deur hul tienerjare, waar hulle aansienlik meer geneig was om aandagprobleme en depressie te hê. Kinders wat aan dagga blootgestel is, was ook byna twee keer so geneig om misdadige gedrag, soos dwelmgebruik, teen die ouderdom van 14 te toon en was meer as twee keer so geneig om gereeld dagga en tabak te gebruik as volwassenes. Die baie konsekwente resultate tussen muise en menslike studies (opgesom in die infografika van Die wetenskaplike hieronder) beklemtoon 'n toenemende begrip van die impak van daggagebruik op ontwikkeling.

Dit is belangrik om daarop te let dat sommige gedragsuitkomste dalk nie heeltemal verband hou met fetale blootstelling aan dagga nie. Kinders van daggagebruikers het dalk in 'n ander sosiale omgewing grootgeword met meer lakse sienings oor dwelms, wat bygedra het tot hul verhoogde dwelmgebruik.

Aangesien dagga steeds gewettig word, moet ons verwag om meer studies oor die gesondheidseffekte en veiligheid daarvan te sien.


Kundige mediese liggame, insluitend die American Academy of Pediatrics (AAP), moedig ouers aan om hul kinders teen 16 siektes in te ent. Die CDC-skedule vir kinderinentings, wat staatmaak op aanbevelings van die Advieskomitee oor Immuniseringspraktyke en deur die AAP onderskryf word, is opgestel op grond van data wat uiteensit wanneer die liggaam se immuunstelsel die beste reaksie op die entstof sal gee en tweedens gebalanseerd teen die behoefte om kinders op die vroegste moontlike ouderdom te beskerm. Daar is geen wetenskaplike data wat 'n mediese voordeel aandui om entstowwe oor 'n langer tydperk as die amptelike aanbevelings te spasiëer nie.

Entstowwe word ook gereeld vir veiligheid geëvalueer. Voordat hulle by die aanbevole regime gevoeg word, moet hulle toetse ondergaan om seker te maak dat hulle nie met mekaar inmeng nie. Veelvuldige studies het ook entstowwe se kumulatiewe effekte geëvalueer.

Tog ondervind pediaters voortdurende druk van sommige bekommerde ouers wat dalk die aanbevole inentings wil versprei of sekere inentings wil uitstel, besluite wat die tydperk van kwesbaarheid vir siektes kan verleng. Byvoorbeeld, 'n nasionaal verteenwoordigende studie gepubliseer in die April 2015 Pediatrie het bevind dat 93 persent van die ondervra dokters in 'n gemiddelde maand ten minste een versoek van ouers ontvang het om skote te versprei. En dit het redelik gereeld gebeur: meer as 'n vyfde van die 534 ondervra dokters het gerapporteer dat 10 persent van ouers sulke versoeke gemaak het. Ouers se wense is dan dikwels nagekom en die meeste van die ondervra klinici het uiteindelik ingestem om dit te doen, ten minste van die tyd.

Tog is vrese oor 'n kind se liggaam wat nie kragtige entstowwe kan hanteer nie, misleidend. Kinders se immuunstelsels reageer op 'n paar honderd vreemde stowwe wat elke dag 'n immuunrespons veroorsaak. Daarteenoor sluit die volledige skedule van aanbevole kinder-inentings minder as 200 antigene in.


IV. Ander laboratoriumondersoeke

Velkanker by knaagdiere

Een van die skakels in die totale bewyse vir die oorsaaklike verband van sigaretrook en longkanker is die demonstrasie dat tabakrookkondensate (gewoonlik na verwys as "teer") die biologiese eienskap het om karsinoom by sekere laboratoriumdiere, veral muise, op te roep. Die produksie van velkanker by muise, na herhaalde, langtermyn toedienings van tabakteer, is nou van ten minste ses verskillende laboratoriums 20, 21, 22, 23, 24, 76 aangemeld. Dit is onteenseglik dat sommige ondersoekers nie positiewe resultate gekry het nie, miskien omdat die dosis en ander eksperimentele toestande anders was, of omdat die komplekse tabakteer waarskynlik baie verskil het in hul samestelling. Die negatiewe resultate van Passey et al. 18 is deur Hueper 38 en ander aangehaal, maar 'n meer onlangse eksperiment deur Passey 24 met Switserse stammuise het wel gelei tot die verskyning van ten minste twee karsinome na herhaalde toediening van tabakrookkondensaat.

Little 29 het aangedui dat "... die ekstrapolasie na die menslike long van resultate verkry deur die verf van of inspuiting in die vel van muise beslis twyfelagtig is". Direkte ekstrapolasie van een spesie na 'n ander is natuurlik nie geregverdig nie. Nietemin stem resultate by diere ten volle ooreen met die epidemiologiese bevindings by die mens. 'n Aanhaling uit Kotin 49 is gepas: “Die chemiese demonstrasie van kankerverwekkende middels in die omgewing en hul suksesvolle gebruik vir die produksie van gewasse in proefdiere bewys nie of selfs veral sterk suggereer 'n soortgelyke verwantskap in die geval van die mens nie. Wanneer daar egter 'n aantoonbare parallellisme tussen epidemiologiese data en laboratoriumbevindings bestaan, word beide groter betekenisvol. Mediese geskiedenis is propvol voorbeelde waarin bewys is dat laboratoriumbevindings uiteindelik hul eweknie in die menslike ervaring het. Uitsonderings was baie min.”

Greene 37, terwyl dit die belangrikheid van die induksie van velkarsinoom in Switserse muise verdiskonteer as gevolg van die grondwetlik "hoë differensiële vatbaarheid" van die stam, glo dat die versuim om neoplasmas te veroorsaak in embrioniese oorplantings wat aan tabakteer blootgestel is, meer belangrike bewyse is. Greene se interessante tegniek lewer wel positiewe resultate wanneer suiwer chemikalieë soos benzo[α]pireen gebruik word, en hierdie chemikalie is uit sommige monsters van tabakrookkondensaat herwin. Ons is nie bekend met verslae van neoplasmas wat in embrioniese weefsel wat blootgestel is nie in vitro tot steenkoolteer, nog 'n ru-mengsel wat karsinogene bevat.

Die hoë frekwensie van karsinoom induksie gerapporteer deur Wynder et al. 76 is nie bereik deur ander ondersoekers nie, wat berig het dat nie meer as 20 persent van diere, en gewoonlik aansienlik minder, karsinoom van die vel ontwikkel het nie. Die teenwoordigheid van kokarsinogene materiale in tabakrookkondensate is deur Gellhorn 22 en deur Bock en Moore 20 gedemonstreer. By die muisdata word nou die data gevoeg oor die induksie van velkanker by sommige konyne geverf met tabakrookkondensaat 77 hierdie kondensaat, wanneer gekombineer met 'n doodgemaakte suspensie van tuberkelbasille, en in 'n brongus ingebring, het 'n karsinoom van die brongus geproduseer in een rot 78 .

Aangesien kwaadaardige neoplasmas in verskeie muisstamme verkry is, en 'n paar neoplasmas in hase en rotte geproduseer is, is die kwessie van stam- of spesiebeperking tot die reaksie moeiliker om te handhaaf. Dit is natuurlik 'n feit dat baie middels wat bewys is dat dit kankerverwekkend is vir die vel van muise, nie kankerverwekkend vir die mens bewys is nie. In die meeste gevalle is daar eenvoudig geen ondervinding met sulke agente by die mens nie, sodat 'n gebrek aan bewys werklik 'n gebrek aan data, pro en con verteenwoordig.

Die probleem van dosis

Little 29 het verder die toepaslikheid van dieredata op die mens bevraagteken, soos volg: "Tabakrook of rookkondensaat het nie daarin geslaag om kanker te produseer selfs op die vel van vatbare muisstamme wanneer dit toegedien word in die hoeveelheid en teen 'n blootstellingstempo wat toestande sou simuleer nie. van menslike rook.”

Die verskille in spesies, weefsels en toestande tussen die induksie van neoplasmas op die vel van muise en in die brongi van die mens, verhinder fyn vergelykings van dosis- en tydverwantskappe.

Brongogene kanker by diere

Die pulmonale adenomatiese gewas in muise, rotte en proefkonyne kan nie vergelyk word met die brongogene karsinoom in die mens 71 nie. Tot 'n paar jaar gelede is die eksperimentele induksie van epidermoïede karsinoom slegs in 'n paar muise bereik deur stringe wat met karsinogene koolwaterstowwe geïmpregneer is, deur die long te stuur. Epidermoïede karsinoom van die long is konsekwent in rotte geproduseer deur berillium 79, deur karsinogeniese koolwaterstowwe wat as vaste korrels in die brongi van rotte 80 ingebring is, en deur inaseming van radioaktiewe deeltjies 81.

Little 29 het opgemerk dat "... langdurige blootstelling van die longe van knaagdiere aan massiewe dosisse sigaretrook nie daarin geslaag het om brongogene kanker te produseer nie." Dit bly waar ten tyde van hierdie verslag, alhoewel dit bevraagteken kan word of enige dier so 'n groot dosis sigaretrook deur indirekte blootstelling ontvang as wat 'n mens deur vrywillige diep inaseming doen. Daarom kan die mislukking 'n tegniese een wees, wat deur verdere eksperimentering opgelos kan word. Die vroeë resultate van Leuchtenberger et al. 19 voorgestel dat dit bereik kan word.

Karsinogene in tabakrook

Die isolasie en identifisering van spesifieke chemiese bestanddele in tabakrook, wat kankerverwekkend is vir die longweefsel van die mens, is 'n belangrike gebied vir navorsing.

Dit is al 'n geruime tyd duidelik dat verbranding of pirolise van die meeste organiese materiaal, insluitend tabak, hoër aromatiese polisikliese van gevestigde karsinogene aktiwiteit sal vorm 28 . 'n Aantal hoër aromatiese polisikliese is geïdentifiseer en geïsoleer (23, 25, 26, 27). Hierdie materiale sluit benzo[e]pireen, benzo[a]pireen, dibenz[a,h]antraseen, chryseen, en, mees onlangs, 'n nuut gevestigde karsinogeen, 3,4-bens-fluoranteen. Of hierdie verbindings ewe betrokke is by menslike pulmonale karsinogenese, is natuurlik vermoedelik.

Little 29 het geïmpliseer dat 'n spesifieke bestanddeel gevind moet word om die biologiese aktiwiteit van tabakrook te verantwoord. Dit is nie nodig nie. Die situasie is soortgelyk aan die vestiging van die karsinogene aktiwiteit van teer, wat aanvaar is voor die isolasie van benzo[a]pyrene deur Kennaway en sy medewerkers. In hierdie geval, ook, benzo[a]pyreen is heel waarskynlik nie die enigste karsinogeen in die komplekse mengsel wat teer genoem word nie, en daar is sterk aanduidings dat sommige nie-karsinogene komponente in teer kokarsinogene effekte kan hê.


Boots anti-rimpel room werk eintlik, sê navorsers

Toe 'n dokumentêr verklaar dat 'n Boots-teenverouderingsroom werklik werk, het voorraad van die serum vinniger verdwyn as fronslyne, met 'n hele jaar se voorraad van die lotion wat binne twee weke van die rakke verdwyn het. Maar die waansin rondom die “No7 Protect and Perfect”-reeks was dalk tog nie so halfgebak nie.

Die resultate van wat vermoedelik die eerste betroubare kliniese proef is van enige anti-rimpelroom wat in die hoofstraat beskikbaar is, dui daarop dat dit werklik help om plooie te verminder.

In wat 'n tweede golf van histerie oor die produk kan veroorsaak, het wetenskaplikes aan die Universiteit van Manchester tot die gevolgtrekking gekom dat ongeveer 'n vyfde van mense wat die room vir ses maande gebruik het, 'n mate van verbetering in hul vel gesien het.

Die verhoor, wat Boots "No.7 Protect and Perfect intense beauty serum" met 'n bevogtiger vergelyk het, is verwelkom deur wetenskaplikes wat gesê het dat dit "die lat verhoog" oor die soort toetse wat kosmetiese maatskappye moet doen voordat hulle eise vir hul produkte maak.

'n Onafhanklike ondersoek deur die BBC se Horizon-program verlede jaar het veroorsaak dat 'n produk uit dieselfde reeks ys gekyk word nadat gevind is dat dit die enigste een is wat getoets is om enige voordelige uitwerking te hê.

"Baie min oor-die-toonbank kosmetiese 'anti-veroudering' produkte is onderwerp aan 'n streng, wetenskaplike proef om hul doeltreffendheid te bewys," sê Chris Griffiths, 'n dermatoloog en leier van die nuwe studie.

Daar is bewys dat voorskrifmedisyne bekend as retinoïede vel wat deur sonblootstelling verouder is, herstel, maar daar is min bewyse dat die oorvloed kosmetiese produkte teen veroudering 'n soortgelyke effek het, het Griffiths bygevoeg.

In die studie het 49 vroue en 11 mans tussen die ouderdomme van 45 en 80 óf die anti-rimpelproduk óf 'n placebo-bevogtigingsroom vir ses maande gebruik. Aan die einde van die tydperk het 43% van diegene wat die anti-rimpel room gebruik het, 'n verbetering in die toestand van hul vel gesien, vergeleke met 22% van diegene wat die placebo room gebruik het.

Toetse op die vrywilligers se vel het getoon dat diegene wat die anti-verouderingsroom gebruik het 'n proteïen genaamd fibrillin-1 vervaardig, wat die vel meer elasties maak. Die navorsing verskyn in die British Journal of Dermatology.

Richard Weller, 'n dermatoloog aan die Universiteit van Edinburgh, het gesê die studie was die eerste behoorlike proef van 'n oor-die-toonbank kosmetiese produk. Hy het gesê die verslag is onduidelik oor hoeveel die room mense se plooie verminder en dit is onwaarskynlik dat dit so doeltreffend sal wees soos retinoïede, wat slegs deur 'n GP voorgeskryf kan word.

Maar die verhoor dui daarop dat ander anti-verouderingsprodukte ook effektief kan wees om plooie te verminder.

"Die bestanddele in Protect and Perfect is beskikbaar vir ander kosmetiese maatskappye, en baie van hulle word in ander handelsmerke van skoonheidsmiddels gebruik. Dit sal my nie verbaas as ander skoonheidsmiddels soortgelyke effekte toon nie, maar dit is aan mededingende kosmetiese maatskappye om dit te wys, "het Weller gesê. "Belangriker nog, ek dink dit sal die lat verhoog vir wat ons van die kosmetiese maatskappye moet verwag om te wys dat hul produkte werk."

Nina Goad, 'n woordvoerder van die Britse Vereniging van Dermatoloë, het gesê: "Ongeveer een uit elke vyf mense wat die room gebruik, sal iets ekstra vir hul geld kry bo gewone bevogtigers. Dit is 'n interessante stap vorentoe in navorsing, hoewel die langtermyn voordele is onbekend. Die belangrikste voorkombare oorsake van velveroudering is sonblootstelling en rook, so as jy bekommerd is oor plooie, is dit verstandig om hierdie faktore te beperk."


Is homoseksualiteit 'n keuse?

Vra hierdie vraag, en jy sal waarskynlik een van twee antwoorde ontvang:

Ja. Mense kies om gay te wees. Hulle maak 'n immorele keuse, wat die regering moet ontmoedig.

Nee. Seksuele voorkeur word biologies bepaal. Die regering behoort gay mense teen diskriminasie te beskerm omdat homoseksualiteit 'n onveranderlike aspek van hul identiteit is.

Hierdie twee antwoorde het iets in gemeen: Met albei ondersteun die wetenskap die morele besluit gerieflik.

&ldquoOm gay te wees is sleg. Hoe wonderlik is dit dat niemand gay hoef te wees nie!&rdquo

&ldquoHomoseksuele gedrag moet toegelaat word om plaas te vind. Is dit nie fantasties dat, deur 'n wonderlike toeval, daar geen manier is om dit te stop nie?

Wat as nie een van die antwoorde reg is nie?

Miskien kan seksuele voorkeur verander word &ndash en mense het die reg om by gay seks betrokke te raak en homoseksuele verhoudings te hê as hulle kies om dit te doen. (Die vierde opsie, dat gay mense geen ander keuse het as om gay te wees nie, maar in elk geval daarvoor gestraf moet word, is moreel ondenkbaar.)

Wat sê die wetenskap vir ons oor seksuele voorkeur?

Ons weet uit baie tweeling- en aannemingstudies dat seksuele voorkeur 'n genetiese komponent het.

'n Gay man is meer geneig as 'n straight man om 'n (biologiese) gay broer te hê lesbiërs is meer geneig as straight vroue om gay susters te hê.

In 1993 het 'n studie wat in die joernaal Science gepubliseer is, getoon dat gesinne met twee homoseksuele broers heel waarskynlik sekere genetiese merkers op 'n streek van die X-chromosoom bekend as Xq28 het. Dit het gelei tot mediaopskrifte oor die moontlikheid van die bestaan ​​van 'n &ldquogay gene&rdquo en besprekings oor die etiek van die aborteer van 'n &ldquogay&rdquo fetus.

Daar was ook opskrifte oor 'n &ldquoalkoholisme-gen, wat mense alkoholiste laat word, en 'n &ldquowarrior-gen&rdquo, wat mense buitengewoon aggressief maak.

Gene kan egter gedrag heeltemal beheer. Gene reguleer die produksie van aminosure, wat kombineer om proteïene te vorm. Die bestaan ​​of afwesigheid van 'n proteïen kan 'n uitwerking hê op dinge soos alkoholverdraagsaamheid of bui.

Om iets te beïnvloed is nie dieselfde as om volkome beheer daaroor te hê nie.

Omgewing, soos genetika, speel 'n belangrike rol in hoe ons gedrag ontwikkel.

Alkoholisme kom in gesinne voor, nie net omdat daar 'n genetiese komponent aan alkoholisme is nie, maar ook omdat kinders leer hoe om stres te hanteer deur te kyk hoe hul ouers en hul ouer broers en susters in stresvolle situasies optree.

As jy uit ’n kultuur kom waar alkoholgebruik verbode is, sal dit vir jou moeilik wees om ’n alkoholis te word, maak nie saak hoe jou liggaam alkohol metaboliseer nie.

Daar is faktore behalwe 'n &ldquowarrior gene&rdquo wat bydra tot aggressie. Kinders leer om aggressief op te tree wanneer hulle sien hoe aggressie beloon word.

As jy in ’n gesin grootgeword het of as deel van ’n kultuur waar aggressie nie goed aanvaar is nie, sal jy minder geneig wees om aggressief te wees. Jy sal van kleins af leer hoe om jou aggressiewe neigings te beheer.

Jou omgewing beïnvloed jou seksuele en romantiese verhoudings.

Deur die geskiedenis heen is huwelike deur gesinsverhoudings en ekonomiese behoeftes beïnvloed.

Mense hou by kulturele beperkings van monogamie ten spyte daarvan dat hulle aangetrokke is tot ander mense as hul gades.

Jou kultuur beïnvloed jou siening oor homoseksualiteit.

In sommige samelewings word homoseksualiteit aanvaar, in ander word dit afgekeur, maar dit word geduld, in nog ander is dit 'n ernstige kriminele oortreding, moontlik met die dood strafbaar.

Manlike homoseksuele gedrag is in antieke Athene verwag. Vandag speel rituele manlike homoseksualiteit 'n belangrike rol in sommige kulture in Nieu-Guinee.

Jou opvoeding kan beïnvloed wat jy wenslik vind en wat jy afstootlik vind. Die meeste Amerikaners sal waarskynlik naar wees as hulle uitvind dat, wanneer hulle gedink het dat hulle beesvleis geëet het, hulle in werklikheid hond eet, al is daar niks inherent ongesond aan hondevleis nie.

Wat jy oor homoseksualiteit geleer het terwyl jy grootgeword het, sal beïnvloed of jy homoseksuele dade as wenslik of walglik beskou.

Sommige mense sal dalk redeneer dat as jy &ldquogeneties gay&rdquo is, maar die gedagte aan homoseksualiteit jou naar maak, dan het jy net die feit aanvaar dat jy werklik gay is. Daardie argument is gebaseer op die aanname dat seksuele voorkeur suiwer biologies is, daarom het dit geen plek in 'n bespreking oor die moontlike oorsake van homoseksualiteit nie.

Die struktuur van die brein kan seksuele voorkeur beïnvloed.

In 1991 het 'n studie wat in die joernaal Science gepubliseer is blykbaar getoon dat die hipotalamus, wat die vrystelling van geslagshormone vanaf die pituïtêre klier beheer, by gay mans verskil van die hipotalamus by reguit mans. Daar is gevind dat die derde interstisiële kern van die anterior hipotalamus (INAH3) meer as twee keer so groot is by heteroseksuele mans as by homoseksuele mans

Hierdie studie is gekritiseer omdat dit breinweefsel gebruik het wat tydens lykskouings verkry is, en al die homoseksuele proefpersone in die studie het vermoedelik aan vigs gesterf.

’n Latere studie, wat in 2001 uitgevoer is, het getoon dat MIV-status geen noemenswaardige effek op die INAH3 het nie. Hierdie studie, wat ook breinweefsel van lykskouings gebruik het, het geen beduidende verskil tussen die grootte van die INAH3 by gay mans en reguit mans aan die lig gebring nie. Dit het egter gewys dat neurone in die INAH3 by gay mans nader aan mekaar gepak is as in straight mans.

PET- en MRI-studies wat in 2008 uitgevoer is, het getoon dat die twee helftes van die brein meer simmetries is by homoseksuele mans en heteroseksuele vroue as by heteroseksuele mans en homoseksuele vroue. Hierdie studies het ook aan die lig gebring dat konneksies in die amigdalas van gay mans ooreenstem met dié van straight vroue by gay vroue, verbindings in die amygdala lyk soos dié van straight mans. Die amigdala het baie reseptore vir geslagshormone en word geassosieer met die verwerking van emosies.

Sommige studies het getoon dat die corpus callosum &ndash die hoofverbinding tussen die twee helftes van die brein- het 'n ander struktuur in gay mans as in straight mans. Ander studies het egter geen verskil gevind nie.

Gay vroue en gay mans is meer geneig om linkshandig of ambidekstrous te wees as reguit vroue en reguit mans, volgens 'n aantal verskillende studies. Sommige navorsers het voorgestel dat hierdie verskil in handigheid en voorkeur vir een hand bo die ander by fetusse waargeneem kan word - verband hou met verskille in die corpus callosum.

'n Studie van 1992 het getoon dat die anterior kommissuur, 'n kleiner verband tussen die brein en twee hemisfere, groter is by homoseksuele mans as by reguit mans. Volgens 'n studie wat tien jaar later uitgevoer is, word die grootte van die anterior kommissuur egter nie deur seksuele oriëntasie beïnvloed nie.

Ons weet uit studie van rotte dat blootstelling aan geslagshormone in die baarmoeder gedurende 'n kritieke tydperk in breinontwikkeling toekomstige seksuele oriëntasie beïnvloed. Deur hormoonvlakke gedurende hierdie tyd te manipuleer, kan wetenskaplikes rotte later aan homoseksuele gedrag laat deelneem.

So jou brein het jou seksuele voorkeur beïnvloed nog voor jy gebore is.

Dit kan verduidelik hoekom baie gay mense voel dat hulle nog altyd gay was.

Breinontwikkeling stop egter nie by geboorte nie.

'n Groot hoeveelheid breinontwikkeling vind plaas gedurende die kinderjare, wanneer jy baie nuwe dinge leer &ndash insluitend hoe jou gesin en die volwassenes rondom jou glo jy moet voel oor dinge en wat hulle glo aanvaarbare gedrag is.

Die opvoeding wat jy as kind ontvang, beïnvloed sterk hoe jou brein sal ontwikkel soos jy groei. Kinders wat musikale opleiding ontvang, ervaar byvoorbeeld veranderinge aan areas van die brein wat met gehoor en motoriese beheer geassosieer word.

Met die regte ervarings kan jou brein verander selfs nadat jy volwassenheid bereik het.

Beide Londense taxibestuurders en professionele klavierstemmers toon toenames in grysstof in areas van die brein wat verband hou met die vaardighede wat nodig is vir hul beroepe. Die grootte van die toename in grysstof korreleer met die aantal jare se ondervinding.

In een eksperiment het bejaarde proefpersone toenames in grysstof in sekere dele van hul brein getoon nadat hulle geleer is om te jongleren.

Met behoorlike rehabilitasie kan mense wat breinskade van beroertes opgedoen het nuwe neurale verbindings ontwikkel en sommige van hul ou vaardighede herwin.

Dit is belangrik om daarop te wys dat die streke van die brein wat getoon is om te verander as gevolg van opleiding en ervaring, nie die dele van die brein is wat met seksuele voorkeur geassosieer is nie.

Vroue ervaar egter veranderinge aan die struktuur van die hipotalamus &ndash wat vermoedelik met seksuele oriëntasie geassosieer word - dwarsdeur die menstruele siklus.

Tot dusver het pogings om homoseksualiteit te genees deur op die brein te opereer en homoseksuele eens lobotomieë gekry het - het nog nooit gewerk nie.

(Pogings om homoseksualiteit uit te skakel via hormoonterapie-toevlugsoord was ook effektief. Terwyl veranderinge in hormoonvlakke in die baarmoeder gedurende 'n baie spesifieke tyd 'n uitwerking op toekomstige seksuele voorkeur kan hê, het hormoonvlakke geen effek op seksuele voorkeur daarna nie. Gay mans en straight mans het dieselfde vlakke van geslagshormone geslagshormoonvlakke is dieselfde by gay vroue en reguit vroue.)

Vandag weet ons egter baie meer van die brein as wat ons geweet het toe homoseksualiteit as 'n siekte beskou is wat behandeling vereis het, en die hoeveelheid kennis wat ons oor die brein het, neem toe.

Perhaps one day we will be able to adjust sexual preference via surgery - focusing on the particular regions of the brain that are associated with sexual preference &ndash or via neural implants or training.

If Sexual Preference Can Be Changed

Even if gay people can never stop being attracted to members of the same sex, they can learn not to act on their desires.

People already learn to stop smoking, to give up certain foods, and not cheat on their husbands or wives.

If we define being gay as engaging in homosexual behavior (the concept of &ldquogay&rdquo as an identity is a Western cultural concept &ndash people who have sex with both men and women may call themselves gay, straight or bisexual, depending on the rules of their culture or subculture), then people stop being gay as soon as they stop engaging in this behavior.

If they could, should they change their brains (or have their brains changed) in order to make themselves straight?

I believe that people have the right to engage in any behavior that they choose, as long as their actions do not harm others, and I believe that gay sex and gay relationships do not cause harm to anyone. Therefore, people who are gay by choice have the right to remain that way

(Of course, there are abusive and unhealthy gay relationships that should not be tolerated, just as there are unhealthy heterosexual relationships that should not be tolerated.)

If sexual preference can be altered, then people who support gay rights can&rsquot rely on the argument that gay people should be protected from discrimination because gay people have no choice but to be gay &ndash an argument that seems like an apology for homosexuality, as if homosexuality is a disease for which there is no cure.

There is an element of homophobia in that argument&ndash the implication that gay people would become straight, if only they could. Supporting gay marriage becomes equivalent to supporting the construction of wheelchair ramps. The &ldquogays can&rsquot help being that way&rdquo approach is reminiscent of the old view of homosexuality as a psychiatric illness.

In a blog post for Slate, J. Bryan Lowder comments on Cynthia Nixon&rsquos claim that her lesbianism is a choice. Lowder agrees with Nixon that blaming biology &ldquocedes a great deal of control to bigoted people.&rdquo

You don&rsquot have to defend a controversial action by arguing that you have no control over your behavior. In fact, when we you do so, you reinforce the belief that your behavior is undesirable.

Nobody has to prove that biology forces them to vote for a particular political party, practice a certain religion or follow a particular diet.

Just as gay people who are happy as they are should not be forced to change their sexual orientation, gay people who want to be straight should have the right to change if they can &ndash and the correct word is &ldquochange&rdquo &ndash not &ldquocure&rdquo.

In his blog post, Lowder states, &ldquoMany critics will argue that appealing to biology is the only way to protect against the attacks of the religious right.&rdquo

It might make these critics unhappy to hear this, but that&rsquos not how science works.

Science doesn&rsquot change in order to support political opinions.

Scientific beliefs change as we gain new information, and sometimes science tells us things that we would rather not hear.

Bailey, J.M. & Pillard, R.C. (1991). A genetic study of male sexual orientation. Archives of General Psychiatry, 48(12): 1089&ndash1096.

Balthazart, J. (2012). Brain development and sexual orientation. Colloquium Series on the Developing Brain, Morgan & Claypool Publishers.

Boyke, J., Driemeyer, J., Gaser, C., Büchel, C. & May, A. (2008). Training induced brain structure changes in the elderly. Journal of Neuroscience, 28(28): 7031-7035.

Maguire, E.A. et al. (2000). Navigational-related structural change in the hippocampi of taxi drivers. Verrigtinge van die Nasionale Akademie van Wetenskappe VSA, 97(8): 4398&ndash4403.

Photo credits: Vancouver Gay Pride Parade 2008 by ecodallaluna on Wikimedia Commons DNA by ynse on Wikimedia Commons Brain fMRI by NASA.

The views expressed are those of the author(s) and are not necessarily those of Scientific American.

OOR DIE OUTEUR(S)

Marcia Malory is a writer who mostly writes about science. She graduated Summa Cum Laude from Brooklyn College with a BA in Political Science, and her writing often focuses on how science affects society. She has worked in various industries on both sides of the Atlantic and now lives in York, England. You can find out more about her by visiting her website


How does smoking affect the body?

Smoking cigarettes can have many adverse effects on the body. Some of these can lead to life-threatening complications.

In fact, according to the Centers for Disease Control and Prevention (CDC) , smoking cigarettes increases the risk of dying from all causes, not just those linked to tobacco use.

Smoking cigarettes affects the respiratory system, the circulatory system, the reproductive system, the skin, and the eyes, and it increases the risk of many different cancers.

In this article, we look at 10 possible effects of smoking cigarettes.

Share on Pinterest Image credit: Stephen Kelly, 2019.

Smoking cigarettes affects lung health because a person breathes in not only nicotine but also a variety of additional chemicals.

Cigarettes are responsible for a substantial increase in the risk of developing lung cancer. This risk is 25 times greater for men and 25.7 times greater for women .

The CDC report that roughly 9 out of 10 lung cancer deaths is linked to smoking.

Smoking cigarettes also presents a greater risk of developing and dying from chronic obstructive pulmonary disorder (COPD). In fact, the American Lung Association report that smoking causes 80 percent of COPD deaths.

Cigarettes are also linked to developing emphysema and chronic bronchitis. They can also trigger or exacerbate an asthma attack.

Smoking cigarettes can damage the heart, blood vessels, and blood cells.

The chemicals and tar in cigarettes can increase a person’s risk of atherosclerosis, which is the buildup of plaque in the blood vessels. This buildup limits blood flow and can lead to dangerous blockages.

Smoking also increases the risk of peripheral artery disease (PAD), which occurs when the arteries to the arms and legs start to narrow, restricting blood flow.

Research shows a direct link between smoking and developing PAD. Even those who used to smoke face a higher risk than people who never smoked.

Having PAD increases the risk of experiencing:

Smoking cigarettes can damage a female’s reproductive system and make it more difficult to get pregnant. This may be because tobacco and the other chemicals in cigarettes affect hormone levels.

In males, the more cigarettes a person smokes and the longer they smoke for, the higher the risk of erectile dysfunction. Smoking can also affect the quality of the sperm and therefore reduce fertility.

According to the CDC , smoking can affect pregnancy and the developing fetus in several ways, including:

  • increasing the risk of ectopic pregnancy
  • reducing the baby’s birth weight
  • increasing the risk of preterm delivery
  • damaging the fetus’s lungs, brain, and central nervous system
  • increasing the risk of sudden infant death syndrome
  • contributing to congenital abnormalities, such as cleft lip or cleft palate

The CDC report that people who smoke regularly have a 30–40 percent higher risk of developing type 2 diabetes than those who do not.

Smoking can also make it more difficult for people with diabetes to manage their condition.

Smoking cigarettes can weaken a person’s immune system, making them more susceptible to illness.

It can also cause additional inflammation in the body.

Smoking cigarettes can cause eye problems, including a greater risk of cataracts and age-related macular degeneration.

Other vision problems related to smoking include:

People who smoke have double the risk of gum disease. This risk increases with the number of cigarettes a person smokes.

Symptoms of gum disease include:

  • swollen and tender gums
  • bleeding when brushing
  • loose teeth
  • sensitive teeth

Smoking tobacco can limit a person’s ability to taste and smell things properly. It can also stain the teeth yellow or brown.

Smoking tobacco can affect a person’s skin and hair. A person who smokes may experience prematurely aged, wrinkled skin. They also have a higher risk of skin cancer, “especially on the lips.”

Smoking can cause the hair and skin to smell of tobacco. It can also contribute to hair loss and balding.

In addition to the well-documented link with lung cancer, smoking cigarettes can also contribute to other forms of cancer.

The American Cancer Society report that cigarette smoking causes 20–30 percent of pancreatic cancers.

People who smoke are also three times as likely to develop bladder cancer than people who do not.

Smoking cigarettes can also double a person’s risk of stomach cancer. Tobacco is especially linked to stomach cancers that occur near the esophagus.

Cigarettes can also increase the risk of:

The ill effects of smoking cigarettes do not only affect people who smoke. Secondhand smoke can also have significant health effects on family members, friends, and coworkers.

Effects of exposure to secondhand smoke include:

  • increasing the risk of colds and ear infections
  • making asthma worse
  • raising blood pressure
  • damaging the heart
  • reducing levels of high-density lipoprotein, or “good,” cholesterol

While quitting smoking can be challenging, the CDC report that today, there are more people who used to smoke than people who currently smoke.

Once a person stops smoking, the benefits start accumulating. These include clearer skin, improved oral health, more stable hormones, a stronger immune system, and a reduced risk of many types of cancers.

Some other benefits of quitting smoking include:

  • After 20 minutes–12 hours: Heart rate and carbon monoxide in the blood drop to normal levels.
  • After 1 year: The risk of a heart attack is much lower, as is blood pressure. Coughing and upper respiratory problems begin to improve.
  • After 2–5 years: The risk of stroke drops to that of someone who does not smoke, according to the CDC .
  • After 5–15 years: The risk of mouth, throat, esophagus, and bladder cancer is reduced by half.
  • After 10 years: The risk of lung cancer and bladder cancer is half that of someone who currently smokes.
  • After 15 years: The risk of heart disease is similar to that of someone who never smoked.

Nicotine is an addictive drug and can cause withdrawal symptoms when a person stops using it. These symptoms including cravings, increased appetite, and irritability. Cravings and other effects typically subside over time.

A doctor or other healthcare professional can help a person take positive steps toward quitting smoking.


Toxic myths about vaccines

Antivaccine activists would have you believe that vaccines are loaded with “toxins” and are therefore dangerous. While there are some chemicals that sound scary in some vaccines, they dose makes the poison, and at the tiny amounts used in vaccines none of these “toxins” are harmful.

Ever since there have been vaccines, there has been an antivaccination movement. It began shortly after Edward Jenner discovered how to use the weaker cowpox virus to induce long-lasting immunity to smallpox, there has been resistance to the concept of vaccination, a resistance that continues to this very day. Reasons for this resistance have ranged from religious, to fear of injecting foreign substances, to simple resistance to the government telling people what to do. Some fear even the infitessimally small risk that vaccines pose for the benefit of resistance to disease far more than they fear the diseases themselves, a result of the very success of modern vaccines. Of course, vaccines, like any other medical intervention, are not without risks, making it easy for them to jump on any hint of harm done by vaccines, whether real or imagined, even though vaccines are among the very safest of treatments.

One of the biggest myths that antivaccinationists believe and like to use to stoke the fear of vaccines is the concept that they are full of “toxins.” The myth that mercury in the thimerosal preservative commonly used in vaccines in the U.S. until early 2002 was a major cause of autism is simply the most recent bogeyman used to try to argue that vaccines do more harm than good, as was the scare campaign engineered in response to Andrew Wakefield’s poor science claiming a link between the MMR vaccine and autism. Now that study after study have failed to find or corroborate a link between thimerosal in vaccines or vaccines in general and autism to the point where even the most zealous of zealots are having a hard time defending the claim that mercury in vaccines cause autism any more, predictably the campaign against vaccines has fallen back on the old “toxins” myth. If you peruse antivaccinationist websites, it won’t take long to find articles claiming that vaccines are full of the most terrifying and nasty toxins. Examples in the media abound as well. For example, Jenny McCarthy, comic actress and former Playboy Playmate who has been doing the talk show and publicity circuit lately to plug her book in which she claims that vaccines caused her son’s autism and that she was able to cure it with “biomedical” interventions and diet, recently gave an interview in which she said:

What I really am is “anti-toxins” in the vaccines. I do believe that there is a correlation between vaccinations and autism. I don’t think it’s the sole cause, but I think they’re triggering–it’s triggering–autism in these kids. A really great example is…is, sometimes obesity can trigger diabetes. I do believe that vaccines can trigger autism…It’s so much more than just mercury. That is one ingredient in the recipe of autism…I’m talking about all of them. I’m calling for cleaning out the toxins. People don’t realize that there is aluminum, ether, antifreeze, still mercury, in the shots…People are afraid of secondhand smoke, but they’re OK with injecting the second worst neurotoxin on the planet in newborns.

Another example of what I sometimes call the “toxin gambit” comes from Deirdre Imus, wife of shock jock Don Imus, with both husband and wife being well-known and reliable media boosters of the claim that vaccines somehow cause autism:

So, where are the evidenced based (conflict free) studies that prove the safety of these “trace” amounts and proof that there are “no biological effects” of any amount of mercury being injected into our children and pregnant moms? Also, where are the evidence based studies proving the safety of vaccines given to pregnant moms and our children that contain other toxins such as aluminum and formaldehyde?

The most recent example of this tactic comes from an organization called Generation Rescue, which just last week ran a full-page ad in USA Today, paid for in part by Jenny McCarthy and her present boyfriend Jim Carrey:

Besides being one of the most egregious examples of a post hoc ergo propter hoc fallacy that I’ve ever seen from an antivaccination site, this Generation Rescue ad demonstrates clearly a new strategy (or, more properly, a resurrection of an old technique) now that science is coming down conclusively against mercury in vaccines as a cause of autism, a strategy of propagating fear by linking vaccines with “toxins.” So what’s the real story? Are there really deadly toxins in vaccines that parents should be worried about?

To answer this question, I thought I’d use what to me is arguably the most amazingly over-the-top examples of this strategy of listing “toxins” in vaccines as a jumping off point. This example is embodied in a post by one Kent Heckenlively writing for the Age of Autism blog entitled FDA Says A-OK: Vaccine Ingredients from A to Z. This post examines a list taken straight from the CDC website of ingredients found in vaccines besides the bacterial or viral proteins designed to evoke the protective immune response and tries to scare parents about almost every one. Of course, nearly all of these comparisons fail to acknowledge that time-honored pharmacological principle that “the dose makes the poison” and extrapolate horrible consequences known to occur during prolonged exposure or exposure to large amounts to the tiny amounts in vaccines. That’s exactly what Mr. Heckenlively does to what is, I must say, a truly ridiculous level. However, as patently ridiculous as Mr. Heckenlively’s post is, I believe that it is not a straw man and still worth starting the discussion with because it serves almost as a reductio ad absurdum concentration of actual arguments that antivaccinationists make about “toxins” in vaccines. A few examples, starting with these, will readily show you what I mean:

Neomycin is used as an anti-bacterial. It is also nephrotoxic and can cause kidney damage.

Polymyxin B is used as an anti-bacterial. It binds to the cell membrane and alters its structure, making it more permeable. The resulting water uptake leads to cell death. Side effects include neurotoxicity and acute renal tubular necrosis.

Streptomycin is used as an anti-bacterial. Streptomycin stops bacterial growth by damaging cell membranes and inhibiting protein synthesis. Specifically, it binds to the 16S rRNA of the bacterial ribosome, interfering with the binding of formyl-methionyl-tRNA to the 30S subunit. This prevents initiation of protein synthesis. Humans have structurally different ribosomes from bacteria, thereby allowing the selectivity of this antibiotic for bacteria. Streptomycin cannot be given orally, but must be administered by regular intramuscular injection. An adverse effect of this medicine is oto-toxicity. It can result in permanent hearing loss.

All of this is true but highly deceptive. Hoekom? The recommended dosage of streptomycin for the treatment of various infections is 20-40 mg/kg per day, for a maximum of 1 g per day! Why is this relevant? Because every vaccine given to a child during his entire life probably doesn’t even come anywhere near 1 mg, that’s why. Antibiotics like streptomycin and neomycin are used in cell culture medium at low concentrations to suppress the growth of bacteria. The reason that these antibiotics are listed is because they’re used in culturing the cells necessary to grow the viruses used in making vaccines. By the time the vaccine is made, these antibiotics are only present in trace amounts, nowhere near enough to cause renal toxicity or ototoxicity, which only occurs with use at or above the range of the doses listed above. I suspect that Mr. Heckenlively knows this too but only mentions it because he knows it will scare parents. Indeed, he takes this sort of distortion to a truly comical extreme with this example:

Sucrose is used as a stabilizer. Over-consumption of sucrose has been linked with some adverse health effects. The most common is dental caries or tooth decay, in which oral bacteria convert sugars (including sucrose) from food into acids that attack tooth enamel. When a large amount of foods that contain a high percentage of sucrose is consumed, beneficial nutrients can be displaced from the diet, which can contribute to an increased risk for chronic disease. It has been suggested that sucrose-containing drinks may be linked to the development of obesity and insulin resistance.

Does Heckenlively honestly think that the baby is eating the vaccine or that there’s kilogram upon kilogram of sucrose in vaccines? Using Mr. Heckenlively’s logic, I could say that because there’s the chelation agent EDTA used in some vaccines as a preservative babies could use it as a treatment for heavy metal poisoning. Sadly, Mr. Heckenlively is not alone in using such distortions to attack vaccines. For example, here are some even more deceptive statements on other such antivaccinationist lists as well about other vaccine ingredients:

Sodium Hydroxide (also known as lye, caustic soda, soda lye.) Is corrosive and is an Eye, skin and respiratory irritant. Can burn eyes, skin and internal organs. Can cause lung and tissue damage, blindness and can be fatal if swallowed. Found in oven cleaners, tub and tile cleaners, toilet bowl cleaners and drain openers.

Hydrochloric acid: CAN DISTROY TISSUE UPON DIRECT CONTACT! Found in aluminum cleaners and rust removers.

Neglected is the simple chemical observation that these effects depend upon the pH of these acids and bases. The reason they’re used in vaccines is to adjust the pH of the vaccine to neutral. The person who wrote these things clearly doesn’t understand the basic concept of pH. Does she honestly think that the pH of vaccines is either 0 (very acid) or 14 (very basic)? Moreover, sodium hydroxide, when it neutralizes an aqueous acid solution will simply form the sodium salt of whatever the anion was in the acid. Hydrochloric acid will form the chloride salt with whatever cation was in the base. When sodium hydroxide or hydrochloric acid are used, one to neutralize the other, the result is an NaCl solution of neutral pH: common table salt.

Of course, this list does contain a number of chemicals that do sound really scary. However, if you remember the pharmacological principle that “the dose makes the poison,” they are much less so. These chemicals are all present at extremely low concentrations in vaccines, certainly not at any dangerous levels. Moreover, some of the fearmongering about such seemingly scary toxins betrays a serious lack of understanding of basic chemistry.

Here’s one example. The aforementioned Jenny McCarthy has been repeating that there is “antifreeze” in vaccines, as she did in the interview linked to earlier. That line is straight off of a number of antivaccination websites. (Amazingly Mr. Heckenlively managed to restrain himself from repeating “the “antifreeze in vaccines” gambit. I can only hope that it is due to intellectual honesty, although I can’t rule out the possibility that he just didn’t know about it.) One website in particular links to an MSDS about Quaker State Antifreeze/Coolant, the principal ingredients of which are ethylene glycol and diethylene glycol. Guess what? There’s no ethylene or diethylene glycol in vaccines. Accurate chemistry or pharmacology never was a major concern among antivaccinationists. After all, Jenny McCarthy also says that there’s “ether” in vaccines, too. The only “ether” I could find in the CDC’s list is polyethylene glycol pisooctylphenyl ether (Triton X-100), a common detergent agent used to make cell membranes permeable. In the past, a compound called Tween-Ether was sometimes used instead of Triton X-100 it’s the same sort of thing, a fairly large organic molecule with an ether chemical group hooked on. I suspect that Jenny and most antivaccinationists are too chemistry-challenged to realize that this is not the same thing as diethyl ether, which was used as an anaesthetic agent before safer volatile agents were developed and is often commonly referred to as just “ether.” Jenny also apparently doesn’t realize that ether is not very soluble in aqueous solution. The only way I could even conceive ether being used in the vaccine manufacturing process is if it’s used for a chemical extraction, in which case, it too would be present in at best trace amounts. Moreover, this may even be one source of the claim that antifreeze is in vaccines as well. Note the first part of the chemical name: “polyethylene glycol.” It just so turns out that a major component of many antifreezes is the chemical ethylene glycol.

I also suspect that the whole “antifreeze in vaccines” canard may have derived from a claim that ethylene glycol is used in the synthesis of thimerosal. In actuality, it’s synthesized using ethyl mercuric chloride, thiosalicylic acid, sodium hydroxide and ethanol, although I don’t know if there are other methods of synthesis that do involve ethylene glycol. The origin of this claim could also come from other trace chemicals in vaccines as well, such as propylene glycol. Either way, even if there were ethylene glycol in vaccines, it would not be at a concentration anywhere near high enough to be toxic or dangerous.

Because mercury hasn’t been in most childhood vaccines for six years, one of the two most favored ingredients that antivaccinationists now like to cite is formaldehyde. Yes, that is indeed the same chemical that’s used to fix tissue for pathology (usually as a 10% solution known as formalin that contains 10 g/100 ml of formaldehyde and is buffered to a neutral pH) and the same chemical used in the embalming fluid for the cadavers we dissected as medical students. (Indeed, I still remember that smell, which was impossible to get rid of entirely during the months I took gross anatomy.) During the vaccine manufacturing process, it’s used to inactivate live virus, and traces do remain after manufacturing. Why on earth would those traces be allowed to remain? Remember again: The dose makes the poison. In trace amounts, formaldehyde is not dangerous. Also, it doesn’t last long in aqueous solution, such as vaccines. It breaks down to formic acid and carbon monoxide. Moreover, exposure to far more formaldehyde than any vaccine contains is ubiquitous in modern life. It’s in auto exhaust, and various substances found in virtually every household emit it:

Latex paint, fingernail hardener, and fingernail polish release a large amount of formaldehyde to the air. Plywood and particle board, as well as furniture and cabinets made from them, fiberglass products, new carpets, decorative laminates, and some permanent press fabrics give off a moderate amount of formaldehyde. Some paper products, such as grocery bags and paper towels, give off small amounts of formaldehyde. Because these products contain formaldehyde, you may also be exposed on the skin by touching or coming in direct contact with them. You may also be exposed to small amounts of formaldehyde in the food you eat. You are not likely to be exposed to formaldehyde in the water you drink because it does not last a long time in water.

Of course, given my background, it’s hard not to mention that every generation of medical students since time immemorial has been exposed to large amounts of formaldehyde. I’m not saying this is a good thing personally I wish I could have avoided it, and it would be a good thing if we could decrease the average exposure to it while going about our activities of life. However, it’s a matter of perspective. Antivaccinationists rant about formaldehyde in vaccines and ignore a source that is orders of magnitude greater over the lifetimes of each and every one of us from childhood to old age: the environment.

Finally, now that thimerosal has been removed from nearly all childhood vaccines, the antivaccinationists needed to find another bogeyman in vaccines to demonize, and, given their fear of heavy metals and belief that chelation therapy to remove them can cure autism, the most obvious candidate was aluminum, which has been used as an adjuvant in many vaccines for over 80 years to increase the ability of antigens to provoke the desired immune response. It has become other of the top two chemicals that antivaccinationists like to cite to demonize vaccines. True, aluminum is not nearly as scary-sounding as mercury, but with mercury falling by the wayside, antivaccinationists are certainly trying very hard to make it so, which brings us back to Mr. Heckenlively’s post:

Aluminum hydroxide, aluminum phosphate, and aluminum potassium sulfate are all used as adjuvants to stimulate the immune system. Aluminum products found in commercial antiperspirants have been linked with breast cancer. A recent article published in the Journal of Inorganic Chemistry based on research from Keele University in England was trying to explain the “known, but unaccounted for, higher incidence of tumors in the upper outer quadrant of the breast.” They found that aluminum content was higher in the outer regions where there would be the highest density of antiperspirant. In discussing aluminum’s potential danger the report stated, “Aluminum is a metalloestrogen, it is genotoxic, is bound by DNA and has been shown to be carcinogenic. It is also a pro-oxidant and this unusual property might provide a mechanistic basis for any putative carcinogenicity. The confirmed presence of aluminum in breast tissue biopsies highlights its potential as a possible factor in the etiology of breast cancer.”

I can’t help but ask here: Applying an aluminum-based compound to one’s skin over the course of many, many years is related to some injections of aluminum-based adjuvants in vaccines exactly…how? Of course, the above claim is a total nonsequitur, but what about the frequent confident claims on antivaccination websites that aluminum causes Alzheimer’s disease and that by implication vaccines cause Alzheimer’s? This is a claim by well-known antivaccinationist Hugh Fudenberg, who is often quoted thusly:

According to Hugh Fudenberg, MD (http://members.aol.com/nitrf), the world’s leading immunogeneticist and 13th most quoted biologist of our times (nearly 850 papers in peer review journals), if an individual has had five consecutive flu shots between 1970 and 1980 (the years studied) his/her chances of getting Alzheimer’s Disease is ten times higher than if they had one, two or no shots. I asked Dr. Fudenberg why this was so and he said it was due to the mercury and aluminum that is in every flu shot (and most childhood shots). The gradual mercury and aluminum buildup in the brain causes cognitive dysfunction. Is that why Alzheimer’s is expected to quadruple? Notes: Recorded from Dr. Fudenberg’s speech at the NVIC International Vaccine Conference, Arlington, VA September, 1997. Quoted with permission. Alzheimer’s to quadruple statement is from John’s Hopkins Newsletter Nov 1998.

Not surprisingly, this claim is not supported by science. There’s no good evidence that the flu vaccine is associated with an increased incidence of Alzheimer’s. Indeed, on his personal blog, my co-blogger Steve Novella has nicely summarized the evidence regarding whether or not aluminum is involved in the pathogenesis of Alzheimer’s disease, concluding:

The evidence of aluminum and AD is mixed, without a clear direction. At present the best answer we have is that aluminum probably does not cause AD but appears to be playing some role, perhaps influencing severity. But even after 42 years, there remains a question mark next to these conclusions. We can rule out that aluminum is the single cause of AD, but whether or not it is an independent risk factor is a qualified “probably not.”

And, most importantly, Steve said this about how the science looking at whether aluminum causes Alzheimer’s disease or not is abused:

The mainstream scientific and patient or disease-oriented groups accurately reflect the above interpretation of the research. But the complexity of the results make it very easy to exploit for the purpose of fear-mongering. The notorious crank website, Rense.com, for example, cherry picks the evidence that suggests there is a correlation and piles it up to present a very distorted view of the issue. There will likely persist rumors, scare e-mails, and conspiracy websites promoting the idea that aluminum causes AD regardless of how the research progresses.

Now the antivaccinationists are climbing aboard the aluminum scare train as well because the scientific evidence is becoming so clear that their previous favorite bogeyman vaccine ingredient, thimerosal, is not associated with autism that even the die-hards are having a hard time arguing that it is anymore, particularly now that thimerosal is no longer present above trace amounts in most childhood vaccines. Consequently, they have no choice but to branch out to other scary-sounding ingredients in vaccines and invoking vague (and, conveniently enough, almost impossible to demonstrate) “environmental toxins” or risk becoming irrelevant.

One thing that you have to remember about resistance to vaccines by groups like Generation Rescue, SafeMinds, and others is that it is not scientific in nature. It is either due to an excessive reliance on anecdotes or confusing correlation with causation (usually with a distrust of science and medicine), or it is ideological in nature. No matter how many of the “toxins” scientists remove from vaccines, it will never be enough for Generation Rescue, Jenny McCarthy, or other antivaccinationists, because it’s all about the vaccines and the very concept of vaccination itself, not any individual ingredients in the vaccines. Antivaccinationists will never come to a point where they say, “OK, now I believe that all the toxins are gone and vaccines are safe.” They’ll either fixate on the viruses or the viral or bacterial antigens themselves, or they’ll make the claim that vaccines are made using “aborted fetuses” because some cell lines used to grow up virus stocks were derived from aborted fetuses 40 or more years ago. If every trace of formaldehyde, aluminum, or any other chemical with more than two syllables in its name were somehow to be removed from all vaccines, they would still be saying things like this:

It is the toxin, or germ, contained in the shot itself that causes the adverse affects on the immune system.

Dead-virus, or live-virus vaccine etc…who cares? The cultures for polio vaccines are grown in the kidney tissue of dead monkeys in third-world countries with little or no controls and the virulent pustule toxin is put in vaccines to be shot into you little kid’s arm. I wouldn’t go into a room where that putrid stuff is, let alone inject it into my blood stream! Would you?

This DNA is from such organisms as various animals, animal/human viruses, fungi and bacteria. It has been documented that the injecting foreign DNA can cause it or some of it to be incorporated into the recipient’s DNA (see ‘Immunisation’ Against Diseases for Children). Remember, nature has not experienced such a direct invasion as this before, so can you be sure that it would have developed a way to protect your body against it?

That pretty much rules out any live attenuated virus vaccine for such an antivaccinationist, doesn’t it? Even worse is this:

The human blood is supposed to be, and traditionally was, sterile – no bacteria (or other organisms) present in it. That is not the case any more. Naturally this has a weakening effect on the immune system, apart from sometimes leading to severe bacterial infections.

No live bacteria is in a vaccine. It is possible, as with any injection, for vaccines to become contaminated with bacteria (which is one reason why preservatives like thimerosal were used for multidose vials, where reuse increases the risk of bacterial contamination), but that is not the intent. What is in vaccines are bacterial proteins, which contain the antigens necessary to provoke the desired immune response.

It would be fascinating to engage an antivaccinationist who makes the claim that he is not “antivaccine” but “antitoxin” or “pro-vaccine safety” in a discussion and ask him this hypothetical question: If formaldehyde, “antifreeze,” aluminum, thimerosal, and every chemical in vaccines circulating in all those lists on antivaccination websites that so frighten you were somehow absolutely removed from the standard childhood vaccines so that not a single molecular remained, would you then vaccinate your child? The only thing that would remain is buffered salt water and the necessary antigens, be they killed virus or bacterial proteins, or whatever.

My guess is that nearly all antivaccinationists would say no, because it’s the “toxin” that makes vaccines work that really disturbs them, as the quotes above clearly demonstrate. Remember that when you see these lists circulating on antivaccinist websites. Remember, too, the principle that the dose makes the poison. Only then will you understand how toxic the myths about vaccines being peddled by antivaccinationists are.


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