University of New Mexico Hazards of Fluoride 1938

8/14/2019 University of New Mexico Hazards of Fluoride 1938

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The University of New MexicoBulletin

w

A STUDY OF THE OCCURENCE OF FLUORINEI N THE D R I N K I N G WATER O F

NEW MEXICOand

THE MENACE O F FLUORINE TO HEALTH

b?jJ OHN X). CLARKAN D EDWARD . M A N N

UNIVER~ITYF NEWMEXICO

THE UNIVERSITY OF NEW MEXICO BULLETINWhole Number 320 August 1, 1988

Cinemistry Series, Volunle 2, No. 5Published monthly in January, March, May, JuB. September, and November, and

semi-monthly in February. April. June, August, October, and Decemberby the University of New Mexico, AIbuquerque, New Mexico

Entered as Second Clam Matter, May 1. 1906 , a t the post office at Albuquerque.New Mexico, under Act of Congress of July 16, 1894


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FLOURINE IN DRINKING WATER

That fluorides had toxic properties was discoveredwhen two chemists, Thenard and Davy became seriouslyill fr om breathing th e vapors of hydrofluoric acid whileattempting to prepare fluorine in a pure state. Louyet andNickles later lost their lives from the inhalation of hydrogenfluoride. Soon after the toxic properties of fluorine werewell established, concern arose as to the probable toxicityof fluorine contaminated drinking waters and foodstuffs inwhich the fluorine may occur naturally or in which i t mighthave been used as a preservative.

Black and McKay (1) were the first to describe mottledenamel in the United States when they found it in certainItalian immigrants. Although their findings seemed topoint toward a local water supply as being responsible, itwas not until 1931 th at i t was found to be due to fluorine inthe water . Proof of thi s consisted of the fact s th at waterwhich was suspected of caursing mottled enamel in the teethof humans also caused it in rats, and that the feeding offlu'orides to other rats brought about th e same condition.

Chemical analyses of waters used by those having defec-tive teeth, and waters not associated with the defect gaveadded proof to the assumption that fluorine was the causalfactor, as the waters associated with mottling containedhigh concentrations of fluorine and those waters not soassociated showed low concentrations. Churchill (2 ) addedfurther evidence by analysing waters from several partsof th e United States, finding high fluorine contents of thewaters in all regions in which mottling is endemic.

Mottled enamel is perhaps most prevalent in the aridsta tes of the Southwest, although it has been reported in atleast one section in twenty-seven states in the United States,and in every country in th e world. The following map, astaken from H. V. and Margaret C. Smith ( 3 ) , and extendedby the use of da ta kindly furnished by them, shows these

[ 3 1


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regions in the United States; the states in which mottledenamel has been reported (4 ) being:ArizonaArkansasCaliforniaColoradoFloridaIdahoIllinois

IowaKansas

LouisianaMinnesotaNevadaNew MexicoNorth CarolinaNorth DakotaOhio

OklahomaOregon

South CarolinaSouth DakotaTennesseeTexasUtahVirginiaWashington

Wisconsin

In 1931, H. V. smith and Margaret C. Smith (5) ofthe University of Arizona made a s tatewide survey of Ari-zona, finding more than forty-five scattered communities inwhich mottled enamel is endemic. The fluorine content ofthe water supplies in these communities varied from one tosix pa rts per million. The only other extensive statewidesurvey that had been made a t that time was one in Colorado.

In April, 1938, Abbott and Voedisch (6 ) reported thefluorine content of t he ground water supplies of NorthDakota.

In 1933 th e United S tates Public Health Service sentquestionnaires to dentis ts and health officers of each countyin New Mexico, regarding mottled teeth. This surveyrevealed approximately one-rthird of New Mexico to beendemic area, particularly the eastern and southwesternsections.

In the first p ar t of 1935, th e city of Albuquerque wasinvestigating the possibility of obtaining an additional watersupply from the Jemez Mountains. Analyses by the seniorauthor revealed some fluorine, and furthe r study for a periodof nearly a year in durat ion was initiated.

This study was conducted by Clark and Beahm (7)from November, 1935, until August, 1936. During thistime samples were obtained from numerous points alongstreams of t he Jemez Country, and, in addition to these,from many other localities whose waters flowed towardAlbuquerque.


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Mr. Beahm also obtained samples from some fifteentown s throughout the state. Although from most of these,samples were sent in only once, their analyses showed aneed for the work now being reported upon.

With some Federal assistance, the Sta te Department ofPublic Health was able to finance the statewide fluorinesurvey of New Mexico which was conducted by the authors.Work on this survey was started early in July, 1937, and

continued until July, 1938. Endeavor was made to analyzewater from every source supplying communities of any sizethroughout the state. In view of th e fa ct tha t th e fluorinecontent of a water supply varies over wide limits fro m timeto time, the att empt was made to repeat the analysis of eachsupply every two weeks. In many cases i t was impossibleto do this fo r various reasons, however the averages of th eresults in these cases are probably not far from correct,when a sufficiently large number of samples were supplied.

The samples were collected by the sanitary inspectorsin each of t he ten health districts and shipped to the Univer-sity where they were analyzed by the Sanchis (8 ) method.At times the waters from certain supplies could not be ana-lyzed by this method, however, these same waters a t anotherdate yielded very well to th e procedure. In general thesewaters a re not potable fo r reasons other than their highfluorine content, so th at it is not imp ortant t ha t these resultsbe included in the survey, although they a re given. Thi ssurvey covered waters f rom 359 different sugplies, of which157 were in communities of considerable size. Of these 157communities some thirty-five have water definitely abovethe danger point of 0.9 pa rt s per million, averagin g fro m 1.1

to well above 12.0 parts per million of fluorine. Twenty-twomore communities are on the dividing line between toxicand nontoxic, their averages varying from 0.8 to 1.0 partpe r million. In this average no community is considered, if

from it there were fewer th an fou r samples, and of thesethe re ar e sixty-five. The map shows the conditions in differ-


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ent areas throughout the state. The green* indicates thoseareas whose water supplies studied, average below 0.8 partsper million of fluorine ; he yellow areas a re those averagingfrom 0.8 to 1.0 p.p.m. inclusive; and the red a reas ar e thosewhose averages ar e from 1.0 p.p.m. up. The following a r edat a concerning fluorine, which we? secured i n this work.I t is obvious that reliance cannot be placed on the averagewhen few samples were supplied.

*The map has been generalized from data at hand. With in-ed volume ofdata, doubtlessly the areas given in wlor on the map would be changed here and there.


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FLUORINE I N PARTS PER MILLION

Number ofLocation of

Samples County :,","$= Minimum MaximumDuring Yr.

Average

Agua FriaAlamedaAlamogordoAlbuquerqueAlcaldeAlgodonesAlma

AmillasAmistadAnimasArtesiaAztecBelenBernalilloBlack River

VillageBlue WaterBurtonCaballoCanoncitoCapulinCarlsbadCarrizozoCentervilleCerrillosChamaChamitaChicoChildersCimarronClaytonCliffCloudcroftClovisColumbusConchas DamCostillaCoyote SpringsCubaDemingDes Moines

Colf axBernalilloOteroBernalilloRio ArribaSandovalCatron

Rio ArribaUnionHidalgoEddySan JuanValenciaSandoval

EddyValenciaLeaSierraBernalilloUnionEddyLincolnUnionSanta FeRio ArribaRio ArribaColfaxLeaColfaxUnionGrantOteroc u r r yLuna

.San MiguelRio ArribaBernalilloSandovalLunaUnion


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FLUORINE I N PARTS PER MILLION-(Continued)

DexterDwyerEl AltoElidaEl RitoEspanolaEstancia

EuniceFairviewFarleyFarmingtonFolsomFort SumnerGalisteoGallupGilaGladstoneGlenwoodGlorietaGrantsGrenvilleHaganHagermanHatchHaydenHobbsHopeHot SpringsHot SpringsHowardIdlewildJ a lJemez SpringsJohnson MesaKirtlandLa BajadoLake ArthurLakeviewLakewood

La LuzLamy

ChavezGrantMoraRooseveltTaosRio ArribaTorrance

LeaSanta FeColf axSan JuanUnionDe BacaSanta FeMcKinleyGrantUnionCatronSanta FeValenciaUnionSandovalChavezDona AnaUnionLeaEddyGrantSierraLeaColfaxLeaSandovalColfaxSan JuanSandovalChavezUnionEddyOteroSanta Fe

16 0.6 1.2

3 0.4 0.6

2 0.5 1.0

20 0.0 3.5

6 0.0 1.5

13 0.6 3.4

1 0.2 0.2

19 1.9 3.61 0.6 0.6

5 0.3 1.4

8 0.2 0.8

2 0.9 1.0

20 - 0.6 1.6

7 0.9 1.3

13 0.4 1.4

6 0.6 3.6

3 0.2 1.0

1 0.1 0.1

11 0.0 0.63 0.2. 0.3

3 0.5 1.1

12 0.4 1.1

16 0.8 1.3

30 0.0 1.2

34 1.0 5.2

8 0.8 1.4

6 0.3 0.9

1 above 12 above 1226 0.4 3.2

7 0.8 1.2

1 0.3 0.3

9 0.8 1.6

15 0.0 1.5

2 0.0 2.2

7 0.4 1.0

16 0.3 1.5

16 0.9 1.2

1 1.4 1.4

6 1.2 1.8

1 0.6 0.6

9 0.7 2.0


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FLUORINE IN PARTS PER MILLION-(Continued)

-Number ofLocation ofSsmplee County .$$% Minimum Maximum Average

During Yr.

LaplataLas CrucesLas VegasLordsburgLovingLovingtonLunaMadridMagulelenaManskerMaxwellMelroseMessengerMillsMineral SpringsMonticelloMoraMosqueroMountainairMt. DoraMule CreekNarajaNew AboOjo CalienteOttoOttowiPasamontePecosPena BlancaPlacitasPlacitasPojuaquePonderosaPortalesQuestaRadium SpringsRamahRatonRed Rock

ResReserve

San JuanDona AnaSan MiguelHidalgoEddyLeaCatronSanta FeSocorroUnionColf axCurryLeaHardingEddySierraM0l.aHardingTorranceUnionGrantDona AnaSocorroTaosUnionSandovalUnionSan MiguelSandovalDona AnaSandovalSanta FeSandovalRooseveltTaosDona AnaMcKinleyColf a xGrant

LunaCatron


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FLUORINE IN PARTS PER MILLION-(Continued)-Number of

Location ofSamples County :,"p",'ffsMinimum Maximum Average

During Yr.

RinconRiversideRodeyRosebudRoswellROYSan Antonito

San JuanSan JuanSan LorenzoSanta CruzSanta FeSanta RosaSan YsidroScholleSenecaSedansocorro '

SpringerStanleySteadSwartzSwastikaTaosTatumTesuqueTexicoThomasThoreau

Tierra AmarillaTucumcariTularosaUte ParkEast VaughnVillanuevaVirdenYates

-Dona Ana 1 2.1 2.1 --Santa 'Fe 11 0.2 0.8 0.5Dona Ana 12 0.4 2.0 1.4Harding 2 2.8 4.0 --Chavez 15 0.3 1.2 0.8Harding 6 0.7 1.6 1.3Bernalillo 19 0.0 0.8 0.2

Grant 1 0.0 0.0--

Rio Arriba 1 0.3 0.3 --Grant 2 0.0 0.2 --Santa Fe 17 0.4 1.2 0.9Santa Fe 3 0.2 0.5Guadalupe 2 0.0 ? - -Sandoval 16 1.0 1.7 1.4Torrance 1 0.0 0.0 --Union 1 1.2 1.2 --Union 6 0.5 1.2 0.9Socorro 6 0.4 0.7 0.G

Colf ax 8 0.0 0.9 0.3Santa Fe 22 1.0 1.8 1.4Union 6 0.5 1.2 0.9Grant 1 0.1 0.1 --Colfax 1 0.2 0.2 --Taos 9 0.0 0.6 0.5Lea 2 1.0 1.3 --Santa Fe 8 0.1 0.7 0.4Curry 1 2.6 2.6 --Union 1 1.8 1.8 --McKinley 4 0.1 0.4 0.3

Rio Arriba 11 0.1 0.7 0.5Quay 19 1.0 2.3 1.8Otero 6 0.2 1.0 0.6Colfax 9 0.0 0.5 0.3Guadalupe 2 0.0 0.7 - -San Miguel 1 0.2 0.2 --Hidalgo 7 1.5 3.0 2.0Harding 6 0.5 2.1 1.2

Copies of such detail furnished the fluorine laboratory at the University by t hesanit arian or health officer who took the samples, concerning location of sample. takenwibhin an y community, have been filed with th e distric t health officer of t ha t commun-ity, th e fluorine content of each water sampl e beinx marked on th e record. Any citizeninkrented in securing detailed information concerning his own locality can get it fromthe health officer of h l ~ ietrict.


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The results of the survey show that many of our water

supplies are high in fluorine, being well above the criticalpoint of 0.9 parts per million at all times, while a greatmajority of those not above the critical point, a s f a r as aver-ages are concerned, are hovering around it, and perhaps50 per cent of the time surpass i t by a small margin.

When we bear in mind that the map has been preparedfrom dat a secured from the analysis of a limited number ofsamples we cannot be too rigid in' our conclusions. How-ever, any community located in the yellow area would do

well to insist that more study* be made of its water supplies.The ill effects of intermittent ingestion of fluorides has beenpointed out by Dr. Smith (9) in her nutrition studies withrats.

*The Lan Vegaa High School Science Club, under the direction of Warren E.Portenier. has set a good example in the matte r of this fur th er study. Thia club hascovered waters from many eourcea. particularly waters from privately owned welle inth e rural dietricte. The club has writte n up a number of ease histories of mottledenamel on the teeth of people residing within th e field of influence of th e echwl. Thisis the type of work which can be carried on under direction of a high school chemimtryteacher. The University d w r a t e d with Mr. Port enie r by sup plyi ng materials, etc..

and a t the initiation of the work, gave some guidance.


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THE MENACE OF FLUORINE TO HEALTH

Fluorine poisoning comes under the head of a publichealth problem because of t he widespread occurrence offluorine in many public and priv ate wate r supplies.

Cases a r e on record which show th a t ingestion of smallamounts of fluorides is fa ta l to both man and other animals.Tappeiner (10) describes the effects of fluorides on dogs,cats, rabbits, and guinea pigs when given by oral ingestion.

When 0.5 of a g ram of sodium fluoride (N aF ) per hundredgr am s of body weight is given orally, or 0.15 of a gr am isgiven by subcutaneous or intervenous injection, the symp-toms ar e as follows: a condition of drowsiness and weak-ness ; cramps which may attack a single organ or the entirebody, and ar e epileptic in cha rac ter ; paralysis of the vaso-motor centers ; acceleration and deepening of the breathingwith paralysis following; vomiting; secretion from thesalivary and te ar g lands; and, finally death.

Certain investigators have observed that vegetationgrowing in the vicinity of aluminum factories, f rom whichfluorine is given off i n the waste gases, absorbs thi s fluorine.The herbiverous animal s of these vicinities exhibit a n en-demic toxicosis which has been attr ibuted to the consumptionof this vegetation, and the above-stated charac teris tic symp-toms of fluorine poisoning have been reproduced by feedingthe suspected forage t o guinea pigs.

From the results of many experiments by Smith andLeverton (9 ) i t ha s been found th at th e compound of fluorineused, the method and leng th of time of administration, andindividual susceptibilities vary t he toxic effects of fluorineto a very grea t extent. The re is evidence, however, tha tfluosilicates such a s sodium fluosilicate (Na2SiF6) ar e moretoxic th an either sodium fluoride (N a F ) o r calcium fluoride(CaF2) and that sodium fluoride is more toxic than thecalcium sal t.

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" 1K S E V

Ails .:;'ERE

I S EV ER E M O T T L I N G !Photognaph bu H . V. a d Margaret C. Smith

Typical cases of mottled enamel, showing the destructive effect offluorine upon human teeth.


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There ar e a t least three types of mottled enamel rec-ognized: the mild chalky type, the more severe stained type,and th e pitted, corroded type. Plate I, as, taken from a paperby Margaret C. Smith (9) of the University of Arizona,shows th e three types of mottling, and, for comparison, a setof normal teeth.

In addition to being dkflgxred, mottled teeth are defec-

tive in formation and calcificatinn and are conseauentlystructurally weak The defect is permanent and, once i t hastaken place, is irreparable. Certain dental associations haveestimated that i t would cost $1,000.00 for the dental care ofthe teeth of the average person with mottled enamel, up toadulthood, at which time the natural teeth must usually bereplaced by false.

Mottled enamel has been produced experimentally byH. V. Smith and Margaret C. Smith (9) of the University

of Arizona. Their experiments consisted of feeding smallamounts of sodium fluoride or water from a supply whichcontained fluorides, to rats, guinea pigs, and dogs. An ideaof the severity of such mottling may be had by comparingth e two pictures of Plate 11, taken fro m Dr. Smith's paper.Picture A shows normal rat incisors and B incisors of ar a t which had been fed sodium fluoride.

Experiments show that the fluorine passes into theblood stream and interferes with the calcification of the

unerupted teeth. Contrary to common belief, i t does notact in th e mouth upon the enamel of the erupted portion ofthe teeth. The teeth of children and adults who have notbegun the drinlcing o f wcuter containing fluorine until theirsecond set o f teeth have erupted , show no m ottling or visibleeffects of fluorine poisoning .

In humans, a s soon as the enamel of th e permanentteeth is completely formed and calcified, the enamel organdisappears. The enamel does not regenerate itself but be-haves like dead tissue, thus once the teeth a re mottled duringchildhood the mottling is permanent.


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The incisors of ra tsgrow continually andregenerate themeselvesabout every thirty days.Experiments at - theUniversity or Arizonain which rats were fedfluorides, show that i t isnot the erupted portionof the teeth which ismottled, but the newgrowth which eruptswithin two to threeweeks after ingestion'.Subcutaneous injectionsof sodium 'fluoride madeon rats also indicatedthat the fluorine goesto the site of enamelformation. Intermittentinjections show thatmottling occurs aftereach injection and thatduring the intervals be-tween injections normalenamel formation againoccurs. Plate I11 showsthe effect of inter-

mittent injections ofsodium fluoride. Differ-ent effects can be pro-duced by varying theinterval between the in-jections and the amountof fluoride injected.Normal enamel areasalternate with t he areas

of defective calcifica-tion, the extent ofwhich corresponds withthe interval between in-

PLATE" I11

Photograph b y H . V . and Mwvaret C . Smith

Effect of intermittent injection ofsodium fluoride.


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Photograph bu H . V . and Margaret C . Smith

a-top; b--center; c-bottom


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Addition of calcium to the diet, however, prevents this lossto a grea t extent, but has no effect in reta rding the mottlingand decay of the teeth. No signs of t he bone defects haveso f a r been observed in children whose teeth ar e mottled andi t is thou gh. t t W wa ter has to contain cv t least six parts permz7llion before any appreciable effects u p o n the bone occur.I t seems$hattheJe&hire-more sensitive to fluorine tha n the

bones since a 'more specific effect is produced on thein.It has been shown by experiments on dogs that the

interference of fluorine wi th calcium metabolism cannot beprevented by th e intake of vitamin D in the fo rm of cod liveroil or viosterol, and the effects on the teeth cannot be pre-vented by an increase in the calcium content of the diet.

Having seen the effects of fluorine on the teeth andbones, we naturally wonder whether there are not othereffects produced in the body from a continued use of fluorine

contaminated water . I t is known that small doses of fluor-ine, which a r e still relatively large compared to t he amountsfound in natural waters, may go so f a r as to produce death.

An inhibitory effect on the action of enzymes, char-acteris tic of antiseptics in general, is a property of all inor-ganic fluorides. Evidence has been established tha t there isa specific influence of fluorides on certain enzymatic changesassociated with carbohydrates and fats. The results of astudy conducted by Kast le and Loevenhart (13) on the effect

of antiseptics on the reactions of pancreatic and liver ex-trac ts revealed a harmful effect of most substances studied.Particularly harmful is the action of sodium fluoride

on th e reactions of lipase. Loevenhart and Pierce (14) in-vestigated the halides of sodium and potassium; the chlor-ides of calcium, cadmium, barium, and manganese ; sodiumnitrate (N aN 03 ) and potassium nitr ate (KNO3) ; disodiumphosphate (Na2HP04) potassium chromate (KPCrOr) ; andammonium thiocyanate (NH,CNS), but none of these sub-

stances showed a n inhibitory effect comparable to th e actionof fluorides. Solutions of sodium fluoride with a fluorine


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content as low as one part in 15,000,000 may inhibit theaction of lipase as much a s 50 per cent.

Certain phases of th e enzymatic breakdown of carbo-hydrates a re particularly sensitive to the fluorine ion. Theability of amylase to produce dextrose is increased by weaksolutions of sodium fluoride.

It has been shown th at th e fluoride ion re tards glycolysisin the blood by preventing glycerophosphoric acid from

changing into phosphoglyceric acid and hence into pyruvicand lactic acids.

Tbere is a small amount of fluorine in normal blood andi t has been shown tha t continued ingestion af fluoride8 mayincrease this amount many fold. Stuber and Lan g (15)observed a number of cases of hzmophilia in which thefluorine content of the blood was abnormally high. Thereseemed to be a correlation between the high fluorine contentof the blood and the prolonged time of coagulation, and they

suspected that the fluorine may be the cause of th is condition.Knowing that goose blood and rabbit blood clots slowly, aninvestigation was made, and it was found th at fluorine waspresent in large amounts in the blood of these animals. Catand dog blood, on the other hand, clots rapidly and wasfound to be free from fluorine.

Continuing their observations they found that as awhole, individuals residing in places where the fluorine con-tent of their drinking water was high, had a coagulation

time of six to twenty times that of a normal individualdrinking fluorine-free water.

Stuber and Lang ar e of th e opinion that the retardingeffect on gIycolysis may be responsible for the long clottingtime.

In closing the topic of the physiological effects of fluor-ine, i t may be stated th at recently Goldemberg (16) reportsth at by th e ingestion of only two milligrams of fluorine perday for a period of six months, the thyroid gland in r ats may

be enlarged five to six times in volume, thus showing thatfluorine poisoning exhibits a very specific effect on the


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thyroid gland. Others do not confirm this work. I t hasbeen suggested that fluorine may play a very important partin endemic goiter.

REMOVAL O F FLUORINE FROM DRINKING WATER

A good summary of many of th e chemical and physicalprinciples which investigators have sought to use in theremoval of fluorine fro m water is to be found in the Amer-ican Journal o f Public Health of April, 1935. Industrialund Engineering Chemistry, in many of its numbers printeddu rin g the past ten years, gives accounts of researches,many by large commercial organizations, seeking large-scalemethods fo r fluorine removal.

H. V. and Margare t C. Smith reported a moderate costmethod of fluorine removal in the November 10,1937, WaterWorks Engineering. Their work is cited in the January,1938, Industrial and Engineering Chemistry as one of th eoutstanding accomplishments in chemistry of 1937.

The authors of th is bulletin concerning fluorine in NewMexico, have also sought a method of removal of fluorine,restricting their very few and preliminary studies to suchmethods as might, if successful, be used by the averagehousewife, in the average kitchen (and the auth ors havehad in mind the isolated ranches in the Southwest). Theyhave taken commercial bone ash, which can be purchasedalready for use, and have heated water to which smallamounts of this material was added. After heating, thebone as h settled to th e bottom of the container. About 80per cent of the water samples so treated (wate rs not toohigh in fluorine) have had their fluorine lowered from toxicto non-toxic quantities by this treatment. For water s ofover 3.0 par ts per million of fluorine, the bone ash was firstput into a flask and covered with water. Hydrochloric acidwas added little a t a time. The bone ash dissolved. Thento th e solution of the bone ash in th e acid, baking soda wasadded until effervescence ceased. This neutralized th e acid.With the neutralization of th e acid solution, by the baking


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soda, the bone ash reprecipitated in flocculent form. Thisprecipiitate was filtered, washed and used, as was the un-treated bone ash as mentioned above. In every case tried,in this preliminary study, this treated bone ash has madean almost complete removal of all fluorine. A five-gallonbottle of water and an electric "bayonet" o r immersionheater were found very convenient in th e laboratory.

The authors are now starting a detailed investigationof the possibility of removal of fluorine by th e use of treatedand untreated bone ash , Work already done has to berepeated. Varying quantities of bone ash have to be used,varying rates and time of heating must be tried, and varied.treatments of bone ash must be attempted before any onebest method, fo r water from any locality, can be determined,if th e results obtained in the few preliminary studies, ar econfirmed and amplified by further investigation.

1. Black and McKay, Dental Cosmos, 58 :132-56 (1916) .2. Churchill, H. V., Znd. and Eng. Chem., 23: 996-98 (1931).3. Smith, H. V. and Smith, M. C., Wate r Works Eng. (Nov. 10,1937).4. Smith, M .C., Am. J . of P . H . , 25: 696-702 (1935).5. Smith, H. V. and Smith, M. C., A&. Exp. Sta. Tech. Bull, 43,

(1932).6. Abbott, G. A. and Voedisch, F. W., No. Dakota Geological Survey

Bull., 11 (1938).7. Beahm, E. Metz, A Stu dy of the Vari ation of the Fluoride Content

of Certain Watersi n

the Vic init y of Albuquerque ( A MastersThesis on file in th e library of the University of New Mexico).8. Sanchis, J. M., I n d . and Eng . Chenz. Anal. E d. , 6: 134-5 (1934).9. Smith, M. C. and Leverton, R. M., I n d . and Eng. Chem., 26: 791-7

(1934).10. Tappeiner, H., Arch. f . exp. Path. u. Pharm., 25: 203 (1889).11. Schour, Isaac, and Smith, M. C., A&. Ex p. St a. Tech. Bztll., 62

(1934).12. Brandl, J., and Tappeiner, H., Zeitsckr. f . Biol., 28: 518 (1891).13. Kastle, J. H., and Loevenhart, A. S., Amer. Chem. Jour., 24: 491

(1900).14. Loevenhart, A. L., and Pierce, G., Jozcr. Biol. Chem., 2 : 397 (1907).15. Stuber, B., and Lang, K., Biochem. Zeitsch r. 212: 96 (1929).

16. Goldemberg, L., Joum. de Physiol. et de Path. Gen. , 25: 65 (1927).

Documents

University of New Mexico Hazards of Fluoride 1938