Document zzv6RE3RrrdmLbKEDdrgdxZ16

M arch 7, 1974 N E W BRUNSWICK, N, J. 0890 R. Schaffner, Ph. D. D irector, Office of P roduct TechnologyBureau of Foods Food and Drug A dm inistration W20a0sh"iCn"g tSotnr,e eDtC 20204 D ear D r. Schaffner: Thank you for your help in arranging a briefing session between Johnson & Johnson and the C om m issioner. As a resu lt of this tshees stiaolnc,/aws beeasrtoe scoqnuteisntuioinng. our c o o p e ra tiv e e ffo rts to help re so lv e We are, therefore, subm itting herew ith the following inform ation: 1) E stim a tio n of T alc D u st E x p o su re fo r In fan ts This re p o rt com prises m easurem ents of dust levels aPcohwiedveerdisw dheunsteadwahnodlereclaantinofg 9thoez.e xoaf gJgOeHraNteSdONhi'SghBdaubsyt condition to m axim um use on babies (frequency and fdTouhrsetmirneigns uetilrmtsi.ne)g eelxicpiotesdu refrolemv etlwios sctoumd ipeas rebdy Ato. tEaldcenT,LVM .D . 2) A proof copy of a p ublication en titled , "T he D etection of C hrysotile A sbestos at Low Levels in Talc by D ifferential T herm al A nalysis" by John P* Schelz, Johnson & Johnson. W ith resp ect to Item (1), we believe the infant exposure data is far in excess of re a l exposure data since it is based on dusting of a whole can of baby powder. How ever, it is being subm itted for w hat ever value it m ay have in your investigation of infant exposure. D r. Schaffner -2- M a rc h 7, 1974 WwF oietohdwo uoautnldwd rDliitrktueegntAopdecrmomninsisiidssietorranttihfoirnso midsattnahoe(t Icateoummthpo1ar)nizyaes. dcoton fmidaeknetiaitl paunbdlitche Very truly yours, JOHNSON & JOHNSON w n:ld h A ttachm ent by: W. N ashed, Ph. D. D irector of Science Inform ation WOn* w o n S u b j e c t : An Estim ated Upper L i m i t f o r T a lc Dust Exposure o f I n f a n t s Compared w i t h the OSHA T hreshold L i m i t Value f o r T alc Miners New B r u n s w ic k , N.J. February 19, 1974 Dr. W. Nashed; Upper l i m i t s f o r t a l c dust exposure f o r in f a n t s in a one week p e rio d were e s tim a te d on a p a r t i c l e - t i m e b a s is from e xpe rim e nta l data s u p p lie d by Dr. F. D. Pooley and A l v in N. Eden, M.D. The expe rim e n ta l values used to es t im a te an upper l i m i t f o r t a l c exposure f o r i n f a n t s were those which correspond to maximum exposure c o n d it io n s . Whenever e s tim a te s were employed, c o n s e rv a tiv e numbers were s e le c te d , th a t i s , values which tended to in crea se the e stim ated exposure. A second e s tim a te was made which more c l o s e l y approximates median ex posure le v e ls o f i n f a n t s to t a l c d u s t , b u t even t h i s was based on c o n s e rv a tiv e assumptions and p ro b a b ly re p re s e n t an exposure le v e l which is g e n e r a lly g r e a te r than norm al. For example, a l l e s tim a te s were based on a p p ly in g the t a l c d i r e c t l y to th e d ia p e r area from a c o n t a in e r , which is the mode o f a p p l i c a t i o n which c re a te s the g r e a t e s t c o n c e n tr a tio n o f t a l c d u s t. An a l t e r n a t e mode which p ro duces s u b s t a n t i a l l y le s s d u s t is employed by many mothers who t r a n s f e r t a l c from the c o n t a in e r to t h e i r hand and g e n t ly s tro k e t h i s powder onto th e i n f a n t . To p r o v id e a basis o f comparison a p a r t i c l e - t i m e exposure was computed f o r a t a l c m iner in c o n ta c t w ith the OSHA T .L .V . f o r t a l c o f 20 mppcf f o r a 40 hour week. T his p a r t i c l e - t i m e exposure value f o r a miner is a t l e a s t 370 tim es the c o rre s p o n d in g upper l i m i t exposure value f o r an i n f a n t and is .about 7840 times the exposure o f an i n f a n t under more n e a rly median c o n d it io n s . For ease o f comparing r e s u lts the exposure le v e ls are presented in the a tta c h e d t a b l e . A complete summary o f the com putations and assumptions are d i s cussed in the attached re p o rt. N. S iv e r ts o n Summary Table Comparing the T a lc Dust Exposure Levels f o r T a lc Miners and I n fa n ts Type o f Estim ate OSHA T .L .V . f o r Miners I n fa n t - Upper L im it Exposure In fa n t - Median Exposure Exposure Levels m ppcf-hrs p e r week 800 2.16 0.102 Ratio o f Miner to In fa n t Exposure -- 370 7,840 ' >l^U-C-T N. S iv e r ts o n Manager S t a t i s t i c a l and Computer O perations cl c February 19 1974 COMPARISON OF TALC DUST EXPOSURE FOR INFANTS AND TALC MINERS J.'N . Sivertson S t a t i s t i c a l & Computer Operations February 19, 1374 TABLE OF CONTENTS Section I. Subject Comparison o f Talc Dust Exposure f o r I n f a n t s and T alc M in e rs. I I . Report by F. D. Pooley on D u sting Experiments Performed w it h JOHNSON'S* Brand Baby Powder. <1-- 1-- -- 1 Data Subm itted by A lv in N. Eden, M.D. I n v e s t i g a t i n g Methods by Which Baby Powder was A p p lie d to I n f a n t s by r Their Mothers. V _ IV. Data Subm itted by A l v in N. Eden, M.D. I n v e s t i g a t i n g Time ( In Seconds) Re q u ire d f o r the A p p li c a t io n o f Baby Powder to D i f f e r e n t Areas o f In fa n ts by Various Methods o f A p p lic a t io n and Weights o f Powder Per A p p lic a t io n V. Summary o f Parameters A sso ciated w ith Powdering a Baby as They A f f e c t the T a lc Cloud Submitted by Dr. F. D. Pooley. * trademark o f JOHNSON & JOHNSON. COMPARISON OF TALC DUST EXPOSURE FOR INFANTS AND TALC MINERS In tro d u c tio n : In t h i s r e p o r t the exposure o f i n f a n t s to t a l c d u st has been es tim a te d from e xpe rim e nta l work conducted by Doctors Pooley and Eden. This exposure is expressed in units o f concentration-hours, th a t is , the product o f the c o n c e n tr a tio n in a i r and the number o f hours in c o n ta c t w i t h t h i s a i r . In t h i s in s ta n c e the c o n c e n tr a t io n is expressed as m i l l i o n p a r t i c l e s p_er cubi fo o t (mppcf) o f a ir ; thus, exposure is expressed in terms o f mppcf-hours (or in some in s ta n c e s , m p p c f-m in u te s ) . I t is p o s s ib le to express the OSHA Thres h o ld L i m i t Value ( T . L . V . ) f o r t a l c miners on a s i m i l a r b a sis in o rd e r to com pare exposures. The e xpe rim e nta l r e s u l t s in the a tta ched re p o r ts by Doctors Pooley and Eden e x h i b i t c o n s id e ra b le v a r i a b i l i t y , and to i l l u s t r a t e the e f f e c t o f t h i s v a r i a b i l i t y two d i f f e r e n t e x p o s u re *e stim a te s w i l l be developed. The f i r s t e s tim a te w i l l be an u p p e r ' l i m i t f o r the exposure o f i n f a n t s to t a l c d u s t , and the second w i l l e s t a b l i s h an exposure le v e l c lo s e r to median con di ti ons. On occasion i t w i l l be necessary t o make c e r t a in assumptions i f e x p e rim e n ta l data are e i t h e r m is s in g o r in c o m p le te . I t w i l l be c le a r from the d is c u s s io n s in the t e x t t h a t assumptions made a f f e c t i n g i n f a n t exposure are p u rp o s e ly made c o n s e rv a tiv e ( i . e . tend t o make the exposure le v e l h ig h ) . Thus, a l l the r e s u lts in c lu d in g the median exposure r e s u lts f o r in fa n ts are probably gre a te r than norm al. -2- E s tim a tio n o f an Upper L i m i t f o r I n f a n t Exposure t o T a lc D u st: I he data on which a l l com putations in t h i s r e p o r t are based may be found in the f o l l o w i n g f o u r r e p o r t s : 1. Report o f Du sting Experiments Performed w ith Johnson & Johnson Baby Powder by Dr. F. D. Pooley o f U n iv e rs ity C ollege, C a rd iff, February 10, 1972. 2. A c l i n i c a l stu d y conducted by A l v in N. Eden, M.D. to determ ine the methods by which baby powder was a p p lie d to i n f a n t s by t h e i r mothers and the d a i l y fre q u e n c ie s o f a p p l i c a t i o n , sub m it t e d November 22, 1971. 3. A second c l i n i c a l study conducted by A lv in N. Eden, M.D. to determ ine the number o f seconds re q u ire d f o r the a p p lic a tio n o f baby powder t o d i f f e r e n t areas o f the i n f a n t s and the w eight o f powder employed. 4. A summary o f Parameters A s s o c ia te d w ith a Baby as They A f f e c t the T alc Cloud by Dr. F. D. Pooley. In re p o rt 1 above, Doctor Pooley sim ulated the a p p lic a tio n o f talcum powder t o the d ia p e r area o f an i n f a n t in a s e rie s o f seven t r i a l s . In o rd e r to o b ta in s u f f i c i e n t l y la rg e dust clouds to sample e f f e c t i v e l y w it h a M in in g Research E s ta b lis h m e n t (M .R .E .) sampler, he emptied a 9 ounce (255 grams) c o n t a in e r o f Johnson's Brand Baby Powder by shaking and squeez ing i n each o f seven e x p e rim e n ts. The le n g th o f time taken to empty each c o n t a in e r ranged from 5.0 to 9 .8 m inutes ( e s tim a te d by d i v i d i n g the t o t a l - 3- a i r volume c o lle c te d in each experim ent by the sampling ra te o f 2.5 l i t e r s p e r m in u te ) . The a i r was sampled from a p o s i t i o n in space a p p ro x im a tin g the lo c a t i o n o f an i n f a n t ' s nose r e l a t i v e to the d u s tin g area. In t h i s s e r ie s o f t e s t s he c o l le c t e d a t o t a l volume o f 137.0 l i t e r s o f a i r ( t o t a l time = 1 3 7 .0 /2 .5 = 5 4 . 8 m inutes) w h ile d u s tin g a t o t a l o f 1785 grams (= 7 x 255) o f powder. This corresponds to an average d u s tin g r a te o f 1785/58.4 = 32.5 grams per minute or 3 2 .6 /6 0 = 0.523 grams per second. In c o n t r a s t Doctor Eden found (R eport 3 above) t h a t the maximum d u s tin g r a te was 0.147 grams per second and the median r a t e , 0.060 grams per second. Thus, Doc t o r Pooley c re a te d dust 0 .5 2 3 /.1 4 7 = 3.56 times f a s t e r than the maximum ob served by D octor Eden in a c tu a l use t e s t s and 0 .5 2 3 /.0 6 0 = 8.72 tim es f a s t e r than the median ra te . Since Doctor Pooley found 2.12 mppcf o f t a l c d u st in a i r a t an a c c e le r a te d d u s tin g r a t e , an e s tim a te o f the t a l c dust c o n c e n tr a tio n under median a p p l i c a t i o n ra te s is o b ta in e d by p r o p o r t io n in g c o n c e n tr a tio n to r a t e as f o l l o w s : 2.12 0.060 0.523 = 0.243 mppcf Note: ( .0 6 0 /. 5 2 3 ) x 100 = 11.5 p e rc e n t. Report 2 contained data regarding the frequency o f ta lc applica t i o n and a p p l i c a t i o n times and Report 3 also contained data about a p p li c a t i o n tim e s . A d a i l y freq uency d i s t r i b u t i o n was prepared from data in -4- R e p o rt 2. This d i s t r i b u t i o n was based on a p p ly in g powder d i r e c t l y from th e c a n i s t e r to the d ia p e r a re a , s in c e t h i s mode o f use re p re s e n ts the type o f a p p lic a tio n employed by 6 7 'p e rc e n t o f the mothers and is the d u s t i e s t mode o f a p p l i c a t i o n . A lth ough data on th e d u r a t io n o f t a l c ap p l i c a t i o n s in th e two r e p o r ts were s i m i l a r , data from R eport 3 was used to prepare a d is tr ib u tio n o f a p p lic a tio n times since the data recorded in th e h o s p it a l was more p r e c is e . Only data p e r t a i n i n g to t im in g the d i r e c t a p p l i c a t i o n o f t a l c to the d ia p e r s i t e was employed. The two freq uency d i s t r i b u t i o n s employed are as f o l l o w s : From Report 2_______________ Frequency o f Use______________ Wei q h t in q F a c to r * D a ily Frequency o f Use 61 22 2 53 64 8 5m 18 6 67 68 J_ 9 ___________From Report 3 _________ A p p li c a t io n Times W e ig h tin g F a c to r * Time in Seconds a 33 34 19 10m 11 15 1 18 4 20 2 25 T o t a l : 43 / T o t a l : 78 m = median value * W eig h tin g f a c t o r s are the number o f times the data were reported in the study. In th e t a b le on the l e f t the f a c t o r s shown represent the o rig in a l weighting factors m u l t i p l i e d by two to e lim in a te f r a c t i o n s . -5- A f t e r t a l c has been a p p lie d the m ajor p o r t io n o f the d u s t cloud s e t t l e s v e ry r a p i d l y as shown by D o ctor Pooley (See Report 4 above and F ig u re I ) . He found, f o r example, t h a t about 2.1 p ercen t o f the t a l c p a r t i c l e s remained in suspension 1.25 m inutes a f t e r the b e g in n in g o f a 10 second (= 0.17 m inute) d u s tin g e x p e rim e n t (See Table I ) . The data in the f i r s t two columns o f Table I were t r a n s c r i b e d from Doctor P o o le y ' s summary d e a lin g w i t h 10 second d u s tin g in th e "room" (R eport 4) o r were e s tim a te d from h is d a ta . Estim ates are i n d ic a t e d by a s t e r i s k s . The "room" data were used, s in c e the room under d is c u s s io n was the same room D o ctor Pooley employed to determine the dust concentrations in his ta lc dusting e x p e ri ments (Report 1). The data in the Column 3 o f Table I re p re s e n t the percentage o f p a r t i c l e s re m a in in g in the a i r a t the end o f the times shown in column 1, and are computed from the data in column 2. These number percentages were then used t o compute the t a l c d u s t c o n c e n tr a tio n s shown in column 4. The numbers in column 4 are percentages o f the 2.12 mppcf o f a i r as determ ined by D o cto r P o o le y 's t a l c d u s tin g s im u la tio n s (R eport 1 ) . Column 5 i n Table 1 is the average concentration o f t a lc dust during the time in te rv a ls in d ica te d by the b ra c k e ts . Using the above data and the curve shown in Figure I an e s tim a t i o n o f an upper l i m i t f o r t a l c d u s t exposure o f an i n f a n t may be made by em plo ying the f o l l o w i n g a d d i t i o n a l in f o r m a t io n and assumptions: -6 1. The maximum tim e r e q u ire d f o r a p p ly in g t a l c d i r e c t l y to an i n f a n t ' s body was re p o rte d by D o ctor Eden (R eport 3) as 25 seconds (0.42 m in u te s ) . 2. The maximum d a i l y frequency f o r t a l c a p p l i c a t i o n to an i n f a n t was re p o rte d by Doctor Eden (R epo rt 2) as 9 tim e s . 3. Two d i f f e r e n t c o n d itio n s and t h e i r a s s o c ia te d time i n t e r vals are re la te d to the exposure o f in fa n ts to ta lc dust. Condition Duration (Mins.) 3.1 D ire ct a p p lic a tio n o f ta lc 0.42 3.2 Period fo r dust s e ttlin g 1.08 The 1.08 m inutes is the d i f f e r e n c e between 1.25 minutes elapsed tim e from the s t a r t o f d u s tin g and the 0.17 minutes (10 seconds) o f dusting described in Report 4 (1.25 - .17 = 1.08). Table f o r E s tim a tin g an Upper L i m i t For In fa n t Exposure to (a le Dust Condition 1. A p p lyin g Talc 2. Dust S e ttle s Duration Mi nutes 0.42 1.08 Talc Concentration mppcf* Exposure mppef-minutes 2..12 1.08. 0.89Q 1.166 Exposure per a p p lica tio n :: 2.056 Upper L im it f o r d a ily exposure 9 x 2.056 = 18.50 mppcf-Minutes Upper L im it f o r Weekly Exposure 18.50 x 7/60 = 2.16 mppcf-Hours *From Column 5 in Table I . -7- Weekly Talc Dust Exposure o f a Miner Working in Dust C oncentrations Corresponding to the QSHA T hreshold L i m i t Value In o rd e r to e s tim a te a weekly exposure o f a t a l c m in e r on an e q u iv a l e n t basis f o r purposes o f com parison, the OSHA T hresho ld l i m i t va lu e ( T . L . V . ) o f 20 mppcf i s employed (Reference b ) . The t o t a l weekly e q u iv a l e n t o f the T .L .V . exposure would be 20 x 40 = 800 m ppcf-H rs. and t h i s number is 370 times g r e a t e r than the upper l i m i t f o r i n f a n t exposure. I t is w orth n o t in g t h a t the f a c t o r o f 370 does n o t take i n t o con s id e ra tio n the d iffe re n c e s in minute volumes ( l i t e r s o f a i r in haled per m in u te ) between an i n f a n t and a m in e r. A cco rd in g to re fe re n c e (a) the max imum m inute volume f o r an i n f a n t is 0.697 l i . per m in u te , w h ile f o r an a d u lt male doing l i g h t work the average value is 28.6 l i . per minute and, at r e s t, i s 7.43. As a c o n s e rv a tiv e e s tim a te c o n s id e r the m iner to be doing l i g h t work 1/4 o f the tim e ; then h is expected m inute volume would be .2 5 ( 2 8 .6 ) + .7 5 ( 7 .4 3 ) = 12.72 l i per m in u te . Thus, th e m iner would, on the average, b reathe 1 2 .7 2 /.5 9 7 = 18.25 times more a i r than the i n f a n t . E s tim a tio n o f An Exposure Level o f I n f a n t s to T a lc Dust Which is C loser to Median C o nditions To e s tim a te an exposure c lo s e r to median c o n d itio n s the f a c t o r s to be co n s id e re d are: 1. The c o n c e n tr a t io n o f t a l c d u s t in the a i r durin g the t a l c a p p l i c a t i o n p e r io d is 0.243 mppcf as shown on page 3, and during the dust s e t tlin g p e rio d , 0.124 mppcf. (11.5 percent o f c o n c e n tr a tio n s shown in T a b l e ' ! , Col. 5 ). -8- 2. The median d a i l y fre q u e n cy o f t a l c a p p l i c a t i o n i s 5. 3. Two d i f f e r e n t c o n d it io n s and t h e i r a s s o c ia te d tim e i n t e r v a l s are r e la t e d to the more n e a r ly median exposure o f in fa n ts to ta lc dust. Condi t i o n 3.1 D ire c t a p p lic a tio n o f t a lc 3.2 Period fo r dust s e ttlin g D u ra ti on 0.17 1.08 Table f o r E s tim a tin g C loser to the Median Exposure o f In fa n ts to Talc Dust Condi t i o n Duration Minutes Talc Concentration ______ mppcf*______ Exposure mppcf-Minutes 1. A p plying Talc 0.17 0.243 0.0413 2. Dust S e ttle s 1.08 0.124 0.1339 i Exposure per a p p lic a tio n : 0.1752 Median d a ily exposure 5 x 0.1752 = 0.875 mppcf-minutes E stim ated Median Weekly Exposure 0.876 x 7/60 = 0.102 mppcf-Hrs. * From Column 6 in Table I . R a tio o f e q u iv a le n t T .L .V . f o r a m iner to the above t o t a l weekly exposure is 800/.102 = 7840. -9- Summary Table Comparing the T a lc Dust Exposure Levels f o r T a lc Miners and I n fa n ts Type o f Estim ate OSHA T .L .V . f o r Miners I n f a n t - Upper L im it Exposure I n f a n t - Median Exposure Exposure Levels m ppcf-hrs per week 800 2.16 0.102 . R a tio o f Mi ner to In fa n t Exposure -- 370 7,840 N. S iv e r ts o n Manager S t a t i s t i c a l and Computer Operations cl c February 19 1974 Table I C o l. 1 Minutes A fter Starting Talc Application 2 Data from Pooley's Talc Dust S e ttlin g Experiment mppcf 3 Percent o f Number Present a t End o f Dusting For 10 Secs (.1 7 M i n . ) 4 P a r tic le Count Estimated From P o o le y 's T alc A p plication Studies mppcf 5 Estimated Count at Interval M idpoint mppcf 6 Estimated Count 11.5% o f Col. 5 mppcf 0.17 4.7* 100.0 2.12 j 2.12 .243 0.25 3.9 83.0 1.76 0.50 1.00 1.25 1.72 .24 . 1* * 36.6 5.1 2.1 0.78 / 0.11 0.045 \ J 1.08 .124 i * Estimated from o rig in a l data: 3.9 - 3.1 = 0.8 0.8 + 3.9 = 4.7 * * Doctor Pooley s ta te d t h a t no a p p re c ia b le c o l l e c t i o n o f p a r t i c l e s was o b ta in e d a f t e r 75 seconds (1.25 M in u te s ) . The c o n c e n tr a tio n a t 1.25 Minutes was e stim a te d to b e *0.1 mppcf. - REFERENCES - (a) B io lo g y Data Book, f e d e r a tio n o f American S o c ie tie s fo r Experimental Biology, p. 220, 1964. (b) "Threshold L im it Values f o r Chemical Substances in Workroom A i r Adopted by ACGIH f o r 1 9 7 3 ", p. 33. Section II REPORT BY F. D. POOLEY ON DUSTING EXPERIMENTS PERFORMED WITH JOHNSON' S* BRAND BABY POWDER * Trademark o f JOHNSON & JOHNSON University College,T FC0a0r4diff- Postal Address: University College, Newport Road, Cardiff CF2 rTA. Telephone Cardiff 442 11 Telegrams: Coleg Cardiff prom D r . F .D . Poo ley Depa rtment of...Miner a1...Exploitation... Report of Dusting Experiment Performed With Johnson and Johnson Baby Powder This report contains the results obtained from an experimental dusting of an infant. The objective of the investigation was to determine the quantity and quality of the dust likely to be produced in the vicinity of an infant subjected to dusting with a container of Johnson and Johnson baby powder. Experimental Procedure The quantity of dust produced in an actual dusting of an infant cannot be effectively measured with standard dust sampling equipment. This is due to the fact that the dusting period is relatively short being in the order of seconds and also because the amount of powder displaced from the container in this short period is insufficient to produce a dust cloud which can be effectively sampled. Simulation of the dusting operation was therefore performed in this investigation by continuously applying the whole of the contents of a container of powder to an area representative of an infant. To sample the dust cloud generated in this operation and likely to be available for inhalation by an infant a gravi metric dust sampling instrument was placed with its sampling orifice in the approximate position of the infant's nose. A second dust sampling instrument was also placed in the position of the nose of the person applying the powder. The instrument employed at the infant's nose was an M.R.E. size selective gravimetric dust sampler with a continuous sampling rate of 2.5 litres/minute. 2 The second sampler was also a size selective gravimetric sampler of the cyclone type, sampling at a rate'of 1.9 litres/ minute. Both instruments have identical size selection charac teristics and also retain the non-selected or oversize airborne particles for analysis. The dust collected by the M.R.E. Sampler 'was deposited onto glass fibre filters while the dust collected in the second instrument (which shall be referred to in the rest of this report as the G.R.V.) was deposited on membrane filters of a cellulose construction. A schematic diagram of the dusting arrangement adopted is given below:- M.R.D.E. Dust D Sampler ^ Air7 / Inlet G.R.V. Dust Sampler 16 ins U 19 ins The powder was continuously shaken from a container from a height varying from 3-5 inches into a shallow tray with one inch side walls. The container was sometimes squeezed as well as being shaken and also inverted and tapped several times during the dusting operation to clear the outlet holes which tended to block. 3 The dusting operation was performed on a table in the centre of a room 12ft by 15ft in size with a ceiling height of approximately' 15ft. Three individuals were used to shake the powder containers each being seated at the table'on which the experiment was performed in a position suitable to perform an actual baby dusting operation. Clean filters were weighed and inserted into the dust sampling instruments which were then placed in position on the table. The instruments were then switched on and a container of powder shaken continuously until empty onto the collecting tray. The instruments were then switched off and taken to a balance room where the filters were reweighed and the dust sampled obtained by weight difference. The room in which the dusting was'performed was allowed to clear by opening all available windows and the one connecting door before repeating the dusting experiment. Before proceeding with the dusting experiments background dust counts in the room were taken using both instruments and the following readings were obtained:- M.R.E. Sampler: Volume sampled 294.0 litres Weight of dust collected on filter = 0.00015 grams. W7eight/litre = 0.0000005 grams. G.R.V. Sampler: Volume sampled 245 litres Weight of dust collected on filter = 0.0001 grams. Weight/litre = 0.0000004 grams. ' The background count in the dusting room can be seen to be very low at between 4 - 5 x.10~7 grams/litre of air. Results: The results obtained for dust concentrations during pow dering simulation tests from both instruments are given in Table 1. M.R.E. Sampler (Positioned at infant's nose) Total: Volume Sampled litres 20.0 15.5 24.5 23.5 16.5 15.5 21.5 137.0 Weight of Dust Sampled grams 0.0002 0.0001 0.00015 0.00015 0.0003 0.0001 0.0001 0.0011 Concentration per - litre 0.00001 0.0000065 0.000006 0.0000065 0.000018 0.0000065 0.0000047 Average volume = 19.57 litres Average dust weight samp1ed = 0.000157 grs. Average dust coneentrtion/litre = 0. Q00.Q08 grms . Average dust concentration/cu metre = 0.008 grams. The variation in the air volume sampled for each of the tests recorded in Table 1 is due to the different time taken by the three persons employed to shake the container of powder. Results obtained from the sampling instrument placed above the dusting area are given in Table 2. TABLE 2 G.R.V. Sampler Cpositioned 18 inches above dusting areal Volume Sampled litres WTeight of Dust Sampled grs Concentration per litre 16.1 0.00025 0.000015 12.0 0.00005 0.00004 12.6 0.00015 0.000012 18.5 0.00015 0.00005 15.5 0.00010 0.000065 15.0 0.00010 0.000067 15.0 0.00010 0.000067 Total: 104.7 0.00090 Average volume = 15.0 litres Average dust weight sampled = 0.00012 grams Average dust concentration/litre = 0.000008 grms Average dust concentration/cu metrre = 0.008 arams Tables 1 and 2 represent the respirable fraction as selected by both machines. It can be seen that an identical airborne concentration was obtained. The actual size distri bution of this material is given by Table 3, which represents five individual determinations of size distribution, three of which were obtained from material sampled by the M.R.E. sampler and two from the G.R.V. sampler. Dust was removed from the M.R.E. glass fibre filter by gently washing it with alcohol. The suspended dust was then sampled onto clean microscope slides and allowed to dry before sizing. The dust sampled by the G.R.V. instrument onto membrane filters was sized directly on the filter by making them transparent with 2-Ethoxyethanol. All size analyses were performed automatically using a Quantimet 720 image analysing device. Each set of results presented in Table 3 was produced sizing over 10,000 particles. TABLE 3 Percentage distribution of particles by number collected by the M.R.E. and G.R.V. samplers. Size Range M.R.E. M.R.E. M.R.E. G.R.V. G.R.V. Av. Microns Sampler Sampler Sampler Sampler Sampler Values % number of particles within each range 0 -0.87 0.87-1.74 1.74-2.61 2.61-3.48 3.48-5.22 5.22-6.96 6.96-17.4 34.8% 12.0 15.5 12.6 14.4 6.6 4.2 37.0% 13.0 15.85 12.5 13.65 5.0 3.2 50.3% 17.85 12.35 7.9 7.3 2.6 1.8 35.1% 8.8 9.5 11.0 17.9 9.9 ` 7.5 49.8% 14.1 12.4 8.5 9.3 3.5 2.1 41.4 13.2 13.1 10.5 12.5 5.5 3.7 100.1 100.2 100.1 99.7 99.7 99.9 Both sampling instruments also collected an oversize or non respirable dust fraction. This oversize fraction was removed from each sampler after completion of all the dusting tests by flushing the lutriation system of each sampler with alcohol to remove the dust which in each'case was then dried, weighed and sized. The results obtained from the two samplers are given below: 6 Non respirable fraction obtained from tire M.R.E. sampler Weight of dust recovered = 0.065 grs. Total amount of dust laden air sampled = 193 litres Concentration of non respirable dust/ litre of air = 0.000337 grs. Concentration of dust/ cu metre -= 0.337 grs. The size distribution of non respirable dust from the M.R.E. sampler obtained using the Quantimet image analyser is given in Table 4. TABLE 4 Size Distribution of Non Respirable Dust Obtained from the M.R.E. sampler Size Range Microns 0-4 4-8 8-12 12-16 16-20 20-30 30-60 above 60 Sample 1 Sample 2 Sample 3 Sample A v . 4 Values % number of particles within each range 30.6% 23.4 15.1 9.9 6.9 9.5 4.5 0.1 25.0% 17.4 13.4 11.0 9.2 13.3 10.1 0.6 33.0% 18.2 8.8 6.7 5.9 12.0 13.8 1.6 28.9% 17.4 9.7 7.8 ' 7.2 13.5 14.1 1.4 29.4% 19.1 11.7 8.9 7.2 12.2 10.6 0.9 100.0 Non Respirable fraction obtained from the G.R.V. sampler Weight of dust recovered = 0.002 grs. Total amount of dust laden air sampled 146 litres Concentration of non respirable dust/litre of air = 0.0000137 grs . Concentration of dust/ cu. metre = 0.0137 grs. The size distribution of the non respirable dust from the G.R.V. sampler obtained using the Quantimet image analyser is given in Table 5. TABLE 5 Size Distribution of Non Respirable Dust obtained from the G.R.V. sampler Size Range Microns 0-4 4-8 8-12 12-16 16-20 20-30 30-60 above 60 Sample 1 Sample 2 Sample 3 Sample 4 AV: Values % number of particles within each range 33.58% 27.38 17.18 9.43 5.20 5.36 1.82 0.05 31.7% 31.05 16.10 9.01 4.90 5.16 2.22 0.04 31.0% 29.5 16.35 9.25 5.67 5.83 2.53 0.06 31.6% 28.9 17.2 10.2 4.9 5.24 1.92 0.04 31.97% 29.21 16.71 9.48 5.14 5.40 2.12 0.05 100.08 The results from the dusting experiment show that the concentration of respirable dust in the vicinity of the infant and parent's nose is the same. The non respirable fraction however, is larger in the vicinity of the infantrs-nose than the parent's. This decrease in larger particles with increase in height above the dusting area is to be expected as these larger particles have a tendancy to settle very rapidly and are therefore only present in large concentrations close to the dusting surface. The respirable fraction, however, contains particles with a very much lower settling speed and these will tend to distribute themselves more readily and evenly in the vicinity of the dusting operation. The size distributions of the respirable fractions from the two samples are very similar. 'X'llAS U l S t r i D U I l O n U I m i e I1UJ.I J. fc iis P X i. a~U-Lc; j_.l a .< ^ u j - w n o i. j. U iu I .U C two samplers is very different, the G.R.V. non respirable size distribution being much finer than the M.R.E. non respirable fraction, which was collected closer to the dusting surface. Samples.of the respirable dust collected in both samplers were combined and subjected to x-ray powder diffraction and the photograph obtained compared with an x-ray powder photograph of a sample of dust from a container of baby powder. The two photographs are illustrated below. It can be seen that they are very similar. Measurement of the ring spacings show that the dust composition is identical with the material contained in the powder containers. X-Ray Pattern From Respirable X-Ray Pattern From Bulk Sample of Baby Powder 10 Assuming a spherical dusting powder particle with a density of 2.88, the weights of single particles of a size corresponding to the mid point of range TD' in Table 6 were then calculated as follows _ Mass ~ Volume .'. 2.88= Mass . . 7T . r 3 x 10" 12 r = particle radius in microns .`.Mass = 2.88 x -- . tt . r 3 x 10" 12 Mid Point of Range D microns 0.43 1.30 2.17 3.04 4.35 6.09 12.18 Mass of Single Parti.cle grams 1.2 x 10 13grs. 3.31 X 10"12grs. 1.54 X 10" 11grs. 4.24 X 10" 1*grs. 1.24 X 10"10grs. 3.39 X 10"1grs. 2.71 X 10"3 grs. Using the mass of single particles and also the % contribution of each size fraction to the total mass, the number of parti cles contained in 0.0001 grams of respirable dust were computed as shown in Table 7. In Table 7 the total dust weight 0.0001 grams has been divided up according to the % contribution of each size frac tion to the total mass to give the actual weight of dust contained in each size fraction (B). This dust weight has then been divided by the weight of a single particle of mid point size in each range CC} to give the number of particles in each range CB^1 Size Range Microns 0-0.87 0.87-1.74 1.74-2.61 2.61-3.48 3.48-5.22 5.22-6.96 6.96-17.4 11 TABLE 7 B Mass of Dust in Size Range grams C Weight of Single Particles in Range B/ c Number of Particles in Range 0.0001 100 X 0.035 1.2 x 10" 13 grs. 29.20 x 104 0.0001 X 0.38 100 3.31 x 10-12grs. 11.46 x 104 0.0001 100 X 1.42 1.54 x 10 11grs. 9.23 x 10 4 0.0001 100 X 3.13 4.24 x 10-11grso 7.38 x 104 0.0001 100 X 10.96 1.24 x 10"1agrs. 8.85 x 104 0.0001 100 X 13.03 3.39 x 10"1grs . 3.85 x 104 0.0001 100 X 71.3 2.71 x 10"9 grs. 2.63 x 104 Total No. of Particles = 72.60 x 104 Assuming a spherical particle and a density of 2.88 it can be seen that a calculated figure of 726,000 particles is obtained for a weight of dust equal to 0.0001 grs. The average number of particles obtained on the G.R.V. membrane filters is given in Table 8. TABLE 8 Particle Number Total Weight Gross____ Number of Particles per 0.0001 grs. 734.000 544.000 472.000 524.000 0.00015 grs. 0.0001 grs. 0.0001 grs. 0.0001 grs. 490.000 '544,000 472.000 524.000 Average Va 507,500 The particle numbers in the last column of Table 8 compare favourably with a computed number of 726,000 per 0.0001 grs. remembering that a spherical particle was assumed for calculation purposes The numbers of respirable particles per cubic metre obtained by converting the gravimetric result, i.e. 0.008 grs/cu metre, is as follows:- ^ 6 ,000 particles/Q.001. grs. Number calculated using the value obtained by particle counting 507,5000/0.0001 grs. 58,OOQ_/-QQQ/cu metre 40,600,000/cu metre A similar calculation was performed to convert the gravi metric weight of non respirable dust collected in the M.R.E. and G.R.V. instruments. The results are as follows:- Number of non Respirable particles/ cu metre obtained in the M.R.E. sampler *5 57 = 16.96 x 106 Number of Non Respirable particles/ cu metre obtained in the G.R.V. sampler = 2.55 x 106 (The calculations from which these two figures were produced are contained in the Appendices). * The total number of particles per cubic metre calculated using a spherical particle and an S.G. of 2.88 for the M.R.E. sampler which approximates to the infant's nose, is as follows- 58.0 x 105 = respirable number 16.96 x 106 = non respirable number- Total = 74.96 x 105 particles/cu. metre. = 2.12 x 105 particles/cu. ft. Number of particles per cubic metre calculated as above for the G. R.V. sampler approximating to the parent's nose is as follows:- 58.0 x 105 = respirable number 2.55 x 10s = non respirable number Total = 60.55 x 106 particles/cu. metre = 1.7 x 10G particles/cu. ft. Both of these figures are peak concentrations obtained while applying dusting powder. 13 CONCLUSIONS The dusting experiments show that the dust concentrations produced in the vicinity of an infant and a parent are several times lower than the recommended levels of 20,000,000 particles per cubic foot. The model of a spherical particle with a density of 2.88 used to compute particle numbers can be assumed to be a fair one. It can be seen from the calculated and counted numbers of particles obtained on several filters from the G.R.V. sampler that the model produces particle numbers approximately 30% higher than those measured with the Quantimet 720 image analyser. This difference should therefore be considered when examining the final particle number concentrations produced. The quality of the dust material produced during dusting corresponds to the material contained in the powder containers, as illustrated by the X-Ray results. 14 APPENDIX 1 Calculation of Particle Number Concentrations from Mass Data of tiie Non Respirable Dust Collected by the M.R.E. Sampler. The size distribution of the non respirable dust collected by the M.R.E . Sampler is given in Table 4. For calculation purposes, those particles above 60 microns are considered to be aggregates composed of particles with a size distribution the same as that of the minus 60 micron material. By considering the plus 60 micron particles to be aggregates this effectively increases the weight of the other size fractions by an amount proportional to their number concentration and size. The calculation of particle number has been performed in an identical manner to the example presented earlier. Table 9 contains the relevant data used to calculate the % contribution of each size fraction to the mass fraction. Size Range Microns 0-4 4-8 8-12 12-16 16-20 20-30 30-60 Mid Point of Range 2 6 10 14 18 25 45 TABLE 9 % Number Weighting % Contribution in Range (Diameter 3) to mass Fraction 29.4% 19.1 11.7 8.9 7.2 12.2 11.5 8 216 1000 2744 5832 15625 91125 0.0178% 0.310 0.887 1.850 3.180 14.470 79.40 100.1148 Assuming spherical particles with a density of 2.88, the weights of single particles corresponding to the mid point of range in Table 9 are given in Table 10. Mld Point of Range Microns 2 6 10 14 18 25 45 15 TABLE 10 Weight of Single Particle in grams h-1 ot-1* h-< 1.2 X grs. 3.26 X lO"10 grs. 1.51 X 10"3 grs. 4.14 X lO"9 grs. 8.80 X 10"9 grs. 2.35 X 10" 8 grs. 1.37 X lo-7 grs. Using the weight of single particles and also the % con tribution of each size fraction to the total mass, the number of particles obtained in a concentration of 0.337 grams per metre of non respirable dust, collected by the M.R.E. sampler, is given in Table 11. iize Range Microns 0-4 4-8 8-12 12-16 16-20 20-30 30-60 TABLE 11 Mass of dust in size range grams 0.337 X 100 0.0178 = 0.0000604 grs. 0.337 X 100 Q.887 = 0.001045 grs. 0.337 X 100 0.887 = 0.002984 grs. 0.337 X 100 1.85 = 0.00623 grs. 0.337 100 X 3.18 = 0.01070 grs. 0.337 100 X 14.47 = 0.04860 grs. 0.337 100 X 79.40 = 0.26630 grs. Number of Particles in range 5.03 x 10G 3.21 x 10s 1.98 x 106 1.51 x 10s 1.21 x 106 2.07 x 10s 1.95 x 105 16.96 x 10e Total number/cu. rmetre = 16.96 x 105 Number/cu. ft. = 4.8 x 105 16 APPENDIX 2 Calculation of Particle Number Concentrations from Mass Data of the Non Respirable Dust collected by the G.R.V. Sampler. The relevant calculations for the particle number are contained in Tables 12 and 13. Again an identical calculation procedure has been adopted to produce particle numbers in each size range. Also the plus 60 micron material has been assumed as aggregates for calculation purposes. TABLE 12 Size Range Microns 0-4 4-8 8-12 12-16 16-20 20-30 30-60 Mid Point of Range 2 6 10 14 18 25 45 % number in Range 31.97 29.21 16.71 9.94 5.14 5.40 2.12 Weighting % Contribution (diameter3) to Mass Fraction 8 216 1000 2744 5832 15625 .91125 0.0717 1.765 4.680 7.310 8.410 23.650 54.100 99.9867 The weight of single particles of mid point of range is the same as that contained in Table 10. 17 TABLE 13 Mass of dust and number of particles in each size range contained in a concentration of 0.0137 grams of dust/ cu. metre as samipled by the G.R.V. sampler Size Range Microns 0-4 4-8 8-12 12-16 16-20 20-30 30-60 Mass of dust in Size Range-grams 0.0137 100 X 0.0717 = 0.00000983 grs. 0.0137 100 X 1.765 = 0.000242 grs. 0.0137 X 4.,68 = 0.00064 . grs. 100 0.0137 100 X 7.31 = 0.001001 grs. 0.0137 100 X 8.41 = 0.001151 grs. 0.0137 100 X 23.65 = 0.00324 grs. 0.0137 100 X 54.10 = 0.0074 grs. Number of Particles in Range 8.19 x 105 7.42 x 105 4.24 x 105 2.42 x 10s 1.31 x 105 1.38 x 105 0.54 x 105 25.50 x 10 5t Number of particles / cu. metre = 2.55 x 10 5 Number / cu . ft. = 7.23 x 10* 10.2.72, Conversion of Gravimetric Data to Number Concentrations As recommended dust levels with Talc are quoted in particle numbers per unit volume of air, an attempt has been made to con vert the weight figures into particle numbers. Several of the membrane filters used to collect dust in the G.R.V. sampler were scanned automatically with the Quantimet 720 image analyser and the number of particles per unit area of filter obtained. This number per unit area was then multiplied by the total filter sur face to give total number of particles per filter. A comparison between the number of particles counted on each filter and the number calculated from the weight of dust on each filter could then be made to test the feasibility of converting mass of dust to numbers of particles. The average size distribution of respirable dust collected by the G.R.V. instrument has been given in Table 3. Using this data and applying a weighting factor for the effect of particle size on the mass of a single dust particle, the % contribution of each size fraction to the total mass of dust collected was derived. The last column in Table 6 represents the percentage contri bution of each of the size fractions to the total mass of a dust sample with a size distribution as given under column A, which is the average size distribution of the sampled respirable fraction as determined from the M.R.E. and G.R.V. samplers and* given in Table 3. TABLE 6 Mass is related to size by the cubic power i.e. A d3 Mass = (density) (tj.tt.C-j) ) = constant x D 3 Size Range Microns DA Mid Point % number of Range in Range A x D3 D Z,(A x D3) Weighting % Contribution (diameter)3 to Mass Fraction 0-0.87 0.43 41.4% .0795 0.035% 0.87-1.74 1.30 13.2 2.200 0.38 1.74-2.61 2.17 13.1 10.200 1.42 2.61-3.48 3.04 10.5 28.00 3.13 3.48-5.22 4.35 12.5 82.30 10.9 6 5.22-6.96 6.09 5.5 226.00 13.03 6.96-17.4 12.18 3.7 1810.00 71.30 ZA x D 3 = 9401.99 100.255