Document b5ZwL23DQjpx1Z0Em054gj5d3

AiianwriMMf JournalofCometto Seiaace 1,177-186 (1979) Normal use levels of respirable cosmetic talc: preliminary study R. I. AYLOTT, G. A. BYRNE, J . D. MIDDLETON* and M. E. ROBERTS, Invereak Reaaarch Iatsroxtloaa] Limited, Edinburgh EH21 7UB, Scotland Received 9 December 1978 Kay v a rie trio, eoroetie taie, rwptiabie particles, strocspharic am pUn, tom abaorpdon ipw troicoyy. This preliminary atudy w u uadtm Jtoa to prorida data from which more comprehensive investigation to wtabliih the safety iamae of coemetic aloe canid he defined. Method for ocflccdng tad analysing retpirsbk tale gmaratad during the us* of loue face powder sad adult and baby duttlng powden v a n utabtiahed. Rwpinbk partidu in the air wen (operand from larger twe pertkha by mean of a cydone and won collected on membrane (Start. The collected duit wet dissolved In add and the tahitloa w u anaiyied for magnesium by atomic abaarptlon ipectroicopy. From the ru u iti the concentrations of Calcin the ah sample* were calculated. The method w u uaod to monitor the in-uao levela of a range of coiimtic taka. Mean concentration in ah tamplad for 3 m k from tha itart of uaa of Orineee trader and Italian 00000 pades of talc formulated for uae aa looaa face powder, adult ducting powder and baby duating powder wen (MS, 1,13 and 0.21 mg ra '1, respectively. Higher levels wen found with ndcrenhed adult duating powder (mean concentration 1.9 mg * '). Thera w u no evidence that tha prawnca of perfume in the tak or tha ambient relative humidity in the range 34-74% during uaa affbeted the level of retphabk tale, but high relative humidity >90% reduced the amount of respirable talc. U tilisation d tt ta la oosmetiquee: tude prlim inaire d u teneurs an talc respirable Rmum Ce travail prliminaire a t entrepris dans la but da fournir d u lments pour une tude plus approfondis sur la scurit d'emploi d u talcs cosmtiques. Des mthode ont t mises au point pour collecter et analyser le tak susceptible d'trt respir Ion de rutilliation de poudres libras pour la visage et Ion du saupoudrage des bbs at d u adultes. Las particule lu plus fiscs da l'air ont t sparas des plut groitires au moyen d'un cyclone et ont t collectes sur d u filtres membrane. La poussire recueillie a t minralise et on a effectu la doage du magnsium sur la solation par iptcooscopie d'absorption atomique' On m a dduit la concentration en tak danr les chantillons d'air considrs. La mthode a t employe pour mesurer une srie da taks cosmtiques dans 1m conditions d'utilisation. La concentration moyenne d'chantillons d'ah prlevs pendant 3 mkutM aprs le dbut de l'utilisation da talc chinois et de taie italien 00000 dans Ut formulations de poudra de ris, de poudre pour adultes et de poudres pour bbs a t * Precast address: Toxicol Laboratories, Ledbury. Herefordshire, HRS 1LG, England. 0142-3463/79/0000-0177 *02.00 C1979 International Journal of Cosmetic Science 177 178 R JA ylottttaL mpeetivamat de 0>S, 1.13, m 041 mj m '\ Dm tecaun plus levesoet t trouves m u n poudre nlaontie pour adultes (moyenne: 1.9 mf m"*). U prsure dt psrfure d ur t* taie, ainsi qu'au humidit ambiant relative oanpiiM antre 54% t 74% n'affiecttnt pu do faon sensible lu tannin en talo mptnbia. Une humidit relative nprleura i 90%conduit la diminution do eu tenottn. INTRODUCTION Cosmetic tale is uud u adult body dusting powder, face powder end baby dusting powder. A recent review article by HildJck-Smith (1) sta tu that although then it only limited scien tific information on tha biological activity of talc from which ita safety can be uaaaied accurately the general indications am that normal exposure to coemetic talc ii not Injurious to health. However, became of the ino w in g internet in hazards posed by dmta, data are inquired on tha amouna of tale to which consumers are expoaed during normal use. Tha main objectives of this study were to devise a suitable methodology for monitoring ln-use concentrations in d r of respirable talc and to define some of the factors which may Influence them. Initially, methods for collecting reapiiable talc during in-use situations and for determining tha quantltlu of talc collected were established. These methods were then used to determine the concentrations of ruplrabie talc in air during tha normal use of s range of different cos metic ta la . The influence of the relative humidity during use and the presence of perfume in the talc on the respirable concentrations of talc were also investigated. EXPERIMENTAL PROCEDURE Materials Chinese perfumed and unperfumed ta la , Italian 00000 grade perfumed and unperfumad tala and Italian micionised grade unperfumed talc were supplied by the Coametic, Toiletry and Perfumary Association Ltd. The Chinese and Italian perfumed talcs contained 0.045 and 0.2% perfume, respectively. Semple oollaetion until Atmospheric samples were taken using apparatus made by C.F. Caseila k Co. Lid, London (2). A cydana elutriator/fllter head system was used for the collection of respirable dust (model A7650/1 fitted with 25 mm diameter membrane filters). The spedfleation of the eiutriator w u that virtually all partides with aerodynamic diameter leu than 1 um, 50% of 5 um partides and no partides greater than 7 urn, would be sampled. The sampled air w u drawn vertically upwards thereby eliminating the majority of particles which would normally Mttla to the ground. In addition, an open filter holder, Le. no elutriation (modal Tl 3070/1), fitted with a 37 mm diameter membrane filter, w u used to collect total dust; in this mode of operation the filter w u located in the vertical position and air w u drawn in at 90* to the vertical. The pumps (modd T13051/2 with built in flow rate indicator), fitted with pulsation dampen (model T13052), were located in static sampler bases and collector supports (model T13076/1). Membrane filters (0.8 un pore size, Mfllipore (UK) Ltd.) were loaded into their holden using forceps In a dean laboratory and transferred to the sampling size Immediately prior to the experiment. The collection units were calibrated to draw air at a rite of 1.9 l rain"1. llHJW (tue Talcing x intarvals o tien units IS cm) at TaWai-Tai Proi Loom face Adult dun Baby dut: Subjt instruct powder sample baby a: talc drv of face or doll' cra(bai Botl run foi unit w; unit w produt to 50 talcing tempe the fit. On sampl< In talcs, devict norm; N< luiim blithr -~tu raprim a. Um wder. sdeniMMd idous tt ire oxing may >iaing mine ( cosm ein uned letry ; ind (2). dust ` the *of WM tally VI). lode the don ode! heir tely .9 1 U nU ofcoanaric tale 179 ItHise studies Taking experiments, each on two occasions with four female subjects, were made at 1 h Intervals over a half day period with the products described In Table I. Two sample collec tion units were set up next to each other (distance between sample collection points about 15 cm) at fees height in each location (Table 0- > Product Teletype Location Lm w thee powder Adult duetbta powder Baby duating powder OUb m , nptfriunad. Italian, 00000 srsda, unparftuned. Italian mtooniaad trade, unperfwned. OifaiM*. pertunod. Chiaaae unperfumed. Italian, 00000 pada, perfumed, Italian, 00000 trade. unperfUmed. Itahea microaieed trade, unperfumed. Chiaew, peftimed. Chinee, unperfumed. Italian, 00300 trade, perfumed. Italian, unparAunad. Waahreora, 2 X 1 a fitted with hand wash bade, mirror there. Sample ooiltcticB looitvd OBihtlf adjusted to fane M ghtia ftoat of mirror. Small window open durini tempting, no other vantUadon. Bathroom, 24 x 2 a , fitted with bath and hand wmhbadn. Samp* collec tion units located on 1J m high afaelf next to bedn. Window d oaad durint tempting, Small room, 3.7 X 24 ra. Contained table tad two chairs. Sample collec tion units located on table 04 m high next to doll's tued. Subjects, alone except during the baby dusting study whan an observer was.pretent, were instructed to uae the talcs In their normal way. In the loose face powder and adult dusting powder studies, subjects were requested to stand with their facet a near aa possible to the sample collection paints. In the baby dusting powder studies a doll was used instead of a real baby and its head wei placed alongside the sampling points. The talcs were applied from talc drums with sprinklar closures of the type commonly used by the public tad in the esse of face powder, by face puffs. Approximate distances from the sampling point! to the user's or doll's nose were 15 cm (loose face powder), 30-90 an (adult dusting powder) and 15-30 cm (baby dusting powder). Both pumps were switched on simultaneously at the start of each talcing operation and run for exactly 5 min. At the end o f each sampling the membrane filter from one collection unit was removed (In the dean laboratory) ind replaced with a new one: the other collection unit wet run consecutively over four talcing operations (total sampling time 20 min) to produce an accumulated sample. The used membrane filters were transferred immediately to 50 ml polypropylene bottles which ware stoppered and retained for analysis. After each talcing operation a record was made of the period during which talc was applied, the ambient temperature and the ambient relidva humidity (whirling wet and dry bulb hygrometer) and the floott and surface of the sampling location were cleaned with a damp doth. On one occasion during each of the three product use experiment, background level samples were taken 30 min before initial use and before each subsequent talcing operation. In two experiments with Italian 00000 grade, unperfumed and Italian micronised grade tala , additional samples were collected using filter holders normally used with the cydone device but with the cydone device removed (i.e. collection of respirable dust plus other dust normally separated by the cydone) and using open filters (l.e. collection of total dust). No attempts were made to control relative humidity except in one experiment with Italian 00000 grade perfumed adult dusting powder when the relative humidity of the bathrooa was maintained at >90% (by steam from heated water batha). 180 R.I. Ayiott ataL Analysis o f ooiaeted temple* Principia. Tho collected samples warn analysed for total magnesium by atomic abtorption spectroscopy (AAS) and the amount of talc calculated from an experimentally determined quantity of magnesium in the talc. Matarais. 'Adatar' gradea of hydrochloric add and 42% hydrofluoric add, `Analar' gradea of boric add (prepared u a 5% w/v aqueous solution), lanthanum chloride aqueous solution (for AAS; 10% w/v lanthanum) and magnesium chloride standard solution (for AAS; 1 mg magnesium mT1) were obtained from BDH Chemicals Ltd. Distilled deionised water was used throughout. Apparatus. A Variar Techtrca model 1400 atonde absorption spectrophotometer fitted with a model 80 automatic Gas Control Unit and a Varan Techtron hollow cathode magnes ium lamp (282.2 run) was used. Instrument conditions were slip width 0 J run, lamp current 3 siA, 4 inch sir-acetylene burner. Polypropylene volumetric wars(Azlon Products Ltd.) was used for all operations involving i hydrofluoric add; otherwise standard laboratory giasswire was used. Calibration procedure. Standards for the calibration curvea were prepared by adding aliquots of a standard magnesium solution to 25 ml polypropylene volumetric flasks, each containing in unused 23 mm membrane filter, followed by hydrochloric add (2 ml) and hydrofluoric add (0.25 ml). After standing overnight, boric add solution (20 ml) was added and, after 0J b, lanthanum chloride solution (1.25 ml) and the solution made up to volume with water. The solutions wan aspirated into the spectrophotometer and the absorbances recorded against a water blank, the data being recorded u a calibration curve. The precision of analysis was calculated from twice the standard deviation (2c) about the mean of the analyses of nina standard solutions containing 0.05 /igm T1 addad magnasium: tha limit of detection was based on the precision o f this concentration. Dattmination of magntsium in taie. Approximately 25 mg quantities of each type of talc wen accurately weighed in triplicate Into 50 ml polypropylene bottles and analysed for total magnesium at described above (but without > membrane filter). Additionally, a range of tan known amounts (0-50 mg) of Chinese unperflimed talc was analysed In the same way. Analysis of sampits. Samples (membrane filters with collected tale) in 50 ml polypro pylene bottles were treated u described for the calibration procedure (without additional membrane filter). After the addition of lanthanum chloride the solutions were transferred quantitatively to 25 ml polypropylene volumetric flasks and made up to volume with water. The absorbances of the solutions were recorded. The amounts of magnesium in tha solutions were computed from the calibration curve and related to the amounts of talc in the samples uring tha experimentally determinad magnesium contest of the talcs. Dattmination o f taie tn atr. The concentration o f talc in the sampled air w u calculated from the amount of talc collected and the volume of air sampled. P m idt tire analysis. Particle tize determination was undertaken on sample* o f Italian 00000 unperftimed and Italian micronised grade te la collected with end without the uee of cyclones. The filter papers were cut into quarters, cam being taken not to disturb the dfled .ving iu*~* mof yted iy. * . the tied Levels o f copnniic tale 181 partlcla. Then etch quarter w u placed on OPX mounting medium (BDH Ltd, refractive index 1J 15) on t clean mkroecope tilde and allowed to dear. Further DPX w u added and a cover (Up waa placed over each preparation. Theae slides were examineduaing a teeeareh mlcroecope (mag X 400) under polarised light when the talc particke w en lean to be anisotropic. The particle sit* w u measured along the gnatest dimension using a calibrated eyepleca micrometer. At least 200 particles were measured from each sample. RESULTS AND DISCUSSION Analytical method A sensitive uulytieal method w u required because of the tntidptted short taldng and sampling tinea and the low fixed sampling rate of the collection device. Analysis of magnes* ium and/or sfllccst by atomic absorption spectroscopy appeared to offer adequate sensitivity and t flame atomisation technique for magnesium w u optimised and used to detarmifle the collected talc (the sensitivity for magnesium being at least two orders of magnitude greater than that for silicon). Electrothermal atomisation w u investigated initially but w u not pursued because the extremely high sendtivity to magnesium of this technique resulted in variable background affects. The optimum medium for dissolving talc samples and the membrane Alter w u found by experiment. Lower magnesium recoveries were found if smaller volumes of hydrochloric add or hydrofluoric add alone were used. In atomic absorption spectroscopy, absorption due to magnesium is suppressed by the presence of silicon. This effect can be overcome or minimised by the addition of a 'releasing agent' such u lanthanum to the inaiyte. However, addition of lanthanum chloride to a solution containing hydrofluoric add causa predpltiticn o f lanthanum fluoride ind it w u therefore necessary to complex excess hydrofluoric add with bode add before the addition oflanthanum (3). Figure 1 shows typical calibration curves obtained with solutions of magnesium in water, reagent matrix and reagent matrix plus (dissolved) membrane filter. Separate experiments showed that the small background sbsorbancst (approx. 0.02 for the reagent matrix; approx. 0.04 for the reegmt matrix plui membrane filter) were due mainly to the boric add end the membrane filter. The magnesium contents o f each type of talc, determined on 25 mg quantities, were as fallows. China* grade, pertamsd: 17.5% (three datenrdnaticas giving 17.0,17J and 18.0% Mg); Chinese grade, unperfumed: 17.3% (17.1,17.2, 173 and 17.7%); Italim 00000 grade, pertained: 17.3% (155, 16A, 18,0 and 19,0%) Itiliin 00000 grade, unperftuned: 17.3% (17.2 and 17.4%); Italian microsdud grade, unperfumed: 18.3% (17.4,18.5 and 18.9%). The results of the experiment in which different amounts of Chinese grade, unpertamed talc were analysed tie shown in Fig, 2. From the slope of the graph the magnesium content w u found to be 17.5% (coefficient of correlation 0.997). As expected with tiles containing different suodsted materials (4) these values u e lower than the theoretical magnesium content (19.23%) based on the empirical formula MgjSltOio (OH)j and were consistent with a lower silicon content (26.5 and 28%, cJ. theoretical value 29.6%) of Chinese un* perfumed tele obtained by us using colorimetry (5) and atomic absorption spectroscopy. Taking tn avenge magnesium content of 17.5% the unsitivity of the method (defined a the concentration of migaesium required to produce 1% absorption it 285.2 am) w u 0.05 14 m f1. The precision of analysis at the 0.05 MgmTl concentration w u 0.005 Mgml" and 182 JU. Ayiott 9taL Ptfum 1. Typical calibrationcur**formagnesium. (a) Aqueous standards; (a) ttandaitU Including reafeat matrix; (e) itu d u d i iadudiat ragant matrix sad btaak mambtana Altar. dtfur* 2. Analysis of m atpariaa la Chinees uaparAuaad tala by atom ic abaorprioe tpactroicopy. tha Omit of Uie (in 25 ml tolutlon) w u 1 u%(0.714 MSrounded up), Tha limits of detection of talc in tingle and accumulated air temples w en set at 0.1 and 0.05 mg n f *, respectively. ItHiee tucRea The result* of the monitoring of concentrations of respirable talc in sir from each product type during the in-use studies are given in Table II which quotes mean data and ranges. The individual results from the ninety-nine separate talcing operations showed that there w u wide variation in taking times and in respirable dust levels generated by the same volunteer using tha tame product on different occasions. Background levels of respirebk.uk .during .the .taking .npetations .sere .daterminad with one type of loose face powder, two type* of adult dusting powder (Italian 00000 and Italian micronised) and one type o f baby dusting powder. When the relatro humidity w u between 54 and 74% detectable background levels of respirable lak vure only found in experiments with Italian mtcroniud talc. However, a single experiment at high humidity (>90%) with Italian 00000 grade dusting powder produced detectable background levels (Table II). f i Tabla It. Ura fern* of rcapiraUc talc (mean o b a iip m o lk n ) hU ud T rictn* N ia te of talcing operadoes* nu( time (i) Looac faoc powder Chinese Italian Italian, mkronhcA 1 Aduli Aliatine powder Safer dotting powder Chinese. perfumed Chinese, anperfuaaed Italian, perfiuned Italian, nnpcrfiimed Italian, fipcifamedt Italian mksonised, unpcifumed Chinese. perfumed Chinese, nopcjfurncd Italian, perfumed Italian, nnpafained * t t 3 t 0 t 0 a * Foul lafejarti need on two panic occadooa. f Measured brfoii cadi b U ti afm lioa. I High humadily cpellaicols. 15-26 (19) 10-2$ (11J) 10-20 Oh) 31-74 (47) 15-57 (36) 15-40 (43) 27-71 (46) 32-54 (46) 31-76 (SI) 15-60 (30) 15-45(26) 1546 (26) 15-35 (25) 16-104 06) 14-20 06) 16-17 06.5) 20-21 (204) 115-12 (20) 164-194 06) 16-19 0 7 4 ) 22-24 (23) 19-21 (20) 19-22 13-44 20-22 12-22 (20) 09) (21) 06) 64-6 (67) 64-71 (66) 66 62-74 (69) 60-74 (66) 61-74 (68) 55-70 (63) 92-100 (97) 54-6 (62) 63-70 (65) 67-72 (69) 60-70 (65) 56-66 (64) <0.1-1.1 (04) < 0.!-0J (0.4) 0.3-1.7 0 5 03-16 (16) 04-14 (1.1) 04-1.7 (04) 04-24 (1.1) 04-04 (0.5) 04-34 (14) <0.1-04 (04) <0.1-0 7 (0.2) <01-0.3 10.1) <0.1-04 (0.2) (laic ao- M i( (m#aa*) Idct (mj '*) 0.1, 0.2 0.1, 0.1 0.4. 0.4 0.3, 1.0 04. 0.5 04. 0.3 .7. 0.1 04 24. 14 84. 0.1 04, 0.05 0.1. 0.05 0.1, OjOS <0.1 - - _ - -- <0.1 <0.1-14 0.6-14 - - <0.1 <0.1 I JOtJMT] 184 R.L Aytott tt aL With the exception of the nticronised te la , the experimental date do not indicate any major difference! between the levels of mapdrsble doit p n e n te d during the use of the different varieties o f etch product type. Therefore, all data from each type o f Chinese grade end Italian 00000 grade talcs have been averaged, taking nan-datestable readings u 0.1 mg ra'\ to give the following mean atmospheric concentrations during the 5 nrin sampling times of respinbla talc (number o f observations In pewntheees): Loom free powder. 0.48 mg re '1 (16) Adult dtutlng pow der 1.13 mg in'* (32) Baby d a tin g pow der 0.21 mg m '1 (32) Them figures suggstt that the greatest quantity of reepirafcle duet it generated during adult dusting operations. By comparison, the mean relue for nricronlaed adult dusting powder was 1.9 mg nT*. A recent separate study uring* different technique showed that the avenge reeptiibk duet exposure of infants during normal talc duiting by mothers wts 0.10 mg m m '1 m '1 (1). There wasno evidence with any of the products that m ambient relative humidity between 34 md 74%influenced the level of respirable talc. However, at high relabel humidity 90% ) a noticeably smaller quantity o f respiribk dust(Italian 00000 grade, perilmted) was collected. This result is attributed to m increased tendency o f d o t particles to aggregate in very moist atmospheres. There was no evidence with any of the products that the presence of perfume influenced the level of respirable talc. It ia o f interest that the amount ofaccumulated respirable talc (Le. collection unit run con* Mcudveiy during four talcing operations) wen generally less thin the mean from individual taking operations (Table H). In fret, the complete date show that o f the twenty-four groups of four consecutive talcing operations, in only five groups did the camulative figure equal or exceed marginally the total of the four individual results while in eleven groups the cumula tive figure was less than 30%- of the aggrepte. We offer no satisfactory explanation for this unexpected result. The possibility of 0) inter-collection device variation d a to inherent geometrical features (the same cyclone, but not necessarily the same pump, was used for >11 accumulated samples), 01) greater spurious contamination during the four individual teldng operations (when the collection device was assembled and taken apart md the simple trans ferred four times) compered with the tingle accumulated sample, and/or (ill) effects d a to ekctraststic charging of the filter m d holder require investigation In another study. Such work is necessary in ordar to dafina sample collection reproducibility. Additional data from those experiments with Italian 00000 unperfluned md Italian rsicroniwd products a n given in Take III when respirable tak , total tile (using filter holders with cyclone device removed) m d total tak (using open filter) were measured. In this case results for each taking operation are given. Aa expected, removal of the cyclone resulted in m increase in the amount o f d o t collected m d demonstrates the effectiveness of the cyclone cover. E m greater quantities o f tak were collected using open filters. A limited number of particis rise distribution analyses ware done with unperfumed Italian 00000 m d mkroiriied pad* talcs. The results (Fig. 3) show that the majority of particles measured wet* between about 1 and 8 on m d demonstrate the difference between the micronised and 00000 grade products m d the efficiency of the cyclone device. Ofcourse, partick tin distribution of ta la from different sources will be expected to vary because of differences in production techniques. Separate experiments were done to determine the smounts of tak typically applied during use. Subjects who had taken part in the earlier pertinents were saked to use the tak in their normal way. An independent observer recorded talcing times and the number of - -O ' f tte trade 1 mg timet tiring wder ertge T th f* WHO 90%) m oiit m od conMuai r***ua r roularthis m at b rill leifig tranaiua to Such tiiim ddars lean tad In don uresd ily of tween QUO, Utt Of ? p iw i tale aer of 1 LenU o fcotmatlc taie 05 TMie III. Um kw h of rwptzable and total taie FSnai number Tkkint order Afflfaimt Ambient i relative C Q humidity {*) Taidna irrpitiTm dnw (i) ffMn<r, hl. Total tale (eydone 0 in r* ) Total tale (open (Star) (mam-*) Italian 00000 p id e , uaparfuaed 1 1 1 IJ 94 32 14 4.7 2 2* 19 94 4 OJ 4.1 9 3 114 97 45 04 2.7 4 4 19 - 32 0 4 4 4 Italian mfereniied pado, oapaifaned S l - 17 6 2 19 41 7 0 4 34 2 2 14 <4 As additional rwpnbl fsaps a ooUeetsd tad n im fa l for partida die dtsotbutioa. 24 27 24 17 10 3 i I ente U*n) Itfur* L PvtteU tu dirtribution. (a) Italian 00000 pad unparfumed tale; (b) Italian mkronised trade tale, (o) Collected with cyctooe; (a) ooBeetad without cyclone. times the contalnar w u ihaken. In each loou face powder experiment the powder puff w u dipped only once into the talc. The amount of talc used w u detannined by weighing the container before and after each subject'! application. The result! (Table IV) show consider able variation in the amount o f talc applied by different Individuals. 186 R.L yiott et aL IkMe JV, Summary of tek usa peam stan ( o m n iu m ta petsntimm) Product Tata type (afl urrpeiftimed) Number of taking operations Talcing time Number of U> ihaket Wright of tsk u a s d d ) Looe fcos powder C h io ttt Italkn 00000 Italian, adcrottieed Adult Chtaeee duattag powder ttaitaa 00000 Italian, ataoalaed 4 4 4 1 I 1 12-22 (17) 13-20 0 6 ) 14-29 (19) - - 0.08-0.22 (0.12) 0.03-0.15 (04) 04)4-04 (04)6) 16-40 (27) 11-80 (41) 13-40 (27) 21-76 (39) 18-65 (31) 19-131 (96) 7-12J (10) 5-12 (U ) 2J-9 (4J) Baby Chtaeee dusting powder Itaden 00000 4 9-29 (19) 7-40 (22) 0J-S (3 J) 4 10-32 (21) 8-41 (24) 0 J-6 0 9 ) ACKNOWLEDGMENT ' The iulhon acknowledge the technical uaiitance of J. K. Ptwell, Mn R. J. Hamilton, Mn I. C. Walker and Mn M. P. Wright. Hie work programme wee initiated and financed by the Comwtic, Toiletry and Perfumery Aiaod atlon Ltd. REFERENCES 1. HHdlck4mith, G. Y. The biology of talc., Sr, /. ML M*& 33 217 (1976). 2. Cualla, C F. Co. Ltd. Instruction leaflet 3107/TG. . 3. Root, J. T. II. and Price, W. i. Compmhennve ichtm t for tin snriyw of csmant by atomic absorption rpectrophotometry. Anatytt 94 89 (1969). 4. Haaw, 0 . H., Roils, P. R. aad Scheie, J. ?. Characterisation of talc and aaaodatad minerals. Am. in i H yi Am. J. 37 294 (1976). 5. SneO, F. D. aadSnaB.C.T. CoiortmuricM tthodtofA naiyti, 3rd edru. VoL 2. p. 6 9 5 .0 . Vast N ean Co. Ino. (1949).