3
Cotton Dust Downloaded from pubs.acs.org by UNIV OF TEXAS AT EL PASO on 10/28/18. For personal use only.
D u s t in C o t t o n G i n s : An O v e r v i e w A. C. GRIFFIN, JR. and E. P. COLUMBUS U.S. Cotton Ginning Laboratory, Stoneville, MS 38776
The results of studies and surveys of air-borne dust conducted in cotton ginneries in the U.S. within the last decade are summarized. Gin dust levels in the major U.S. production areas were found to be in the same range for similarly harvested cotton. Gins processing machine -stripped cotton had higher dust levels than those handling spindle-picked cotton, and roller gins were dustier than saw gins. The location of a gin in relation to its dust and trash collecting equipment outside the gin was of major importance in the occurrence of dust in gins, and the dust content of ambient air outside gins also had a major impact on dust levels within gins. Parti culate size, concentration and chemical constit uent data are also reported. The c r i t e r i a document (J.) f o r a recommended standard f o r o c c u p a t i o n a l exposure t o c o t t o n dust d e f i n e s c o t t o n dust as dust generated i n t o the atmosphere as a r e s u l t of the processing of c o t t o n f i b e r s combined w i t h any n a t u r a l l y o c c u r r i n g m a t e r i a l s such as stems, leaves, b r a c t s , and i n o r g a n i c matter which may have accumulated on the c o t t o n f i b e r s during the growing o r harvesting period. Our i n t e r e s t i n cotton dust has three aspects. One has to do w i t h the p h y s i c a l e f f e c t s of c o t t o n dust on the processing performance of c o t t o n i n spinning m i l l s . Excessive amounts of c o t t o n dust may cause machinery stoppages and thereby add t o product manufacturing c o s t s . The second aspect concerns the h e a l t h of workers i n c o t t o n spinning m i l l s and c o t t o n g i n s ; and the t h i r d aspect i s that of g i n emissions i n t o the ambient atmosphere. The recent U.S. Environmental P r o t e c t i o n Agency (EPA) r e p o r t (2^) l i s t i n g cotton g i n s as one of the seven
This chapter not subject to U.S. copyright. Published 1982 American Chemical Society.
28
COTTON
DUST
primary sources of atmospheric a r s e n i c g i v e s an added sense of urgency t o the need f o r c a r e f u l study of the s i t u a t i o n . This r e port r e l a t e s t o the h e a l t h of g i n employees and i s a general summary of our knowledge of dust i n and around c o t t o n g i n s . There were 2,332 a c t i v e g i n s i n the U.S. i n 1979 ( 3 ) . These g i n s w i t h a t y p i c a l employment of 9 persons per s h i f t , ginned 14,161,000 bales of c o t t o n . These bales may be subdivided by c o t t o n type i n t o about 14,061,000 bales of Upland c o t t o n and 100,000 bales of American Pirna c o t t o n . The Upland cottons have s h o r t e r , weaker, and higher m i c r o n a i r e f i b e r than the Pima c o t t o n s , and are ginned on g i n s using the saw-and-rib p r i n c i p l e whereas the Pirnas are ginned on r o l l e r g i n s that c r e a t e fewer f i b e r neps. The method of h a r v e s t i n g c o t t o n o f f e r s another i n t e r e s t i n g way of c a t e g o r i z i n g the crop; h a r v e s t i n g by s p i n d l e p i c k e r s accounted f o r 62 percent of the crop w i t h s t r i p p e r h a r v e s t i n g accounting f o r 37 percent of the crop. The methods of harvest and g i n n i n g w i l l be important as the dust and i t s composition data a r e presented. Dust L e v e l s i n Ambient Atmosphere Our f i r s t c o t t o n dust measurements were made i n 1967 when one of the authors of t h i s paper measured the ambient dust c o n c e n t r a t i o n s downwind from three M i s s i s s i p p i c o t t o n g i n s (_4). The r e s u l t s of t h i s study showed that u n c o n t r o l l a b l e v a r i a t i o n s i n wind d i r e c t i o n and v e l o c i t y during sampling a d v e r s e l y a f f e c t e d the r e l i a b i l i t y of the measurements and made the data d i f f i c u l t to analyze. I t was a l s o found that the a i r b o r n e dust burden by winds from unpaved approach roads and c o t t o n - t r a i l e r parking areas o f t e n overshadowed that emitted by the g i n s . I t soon became apparent that the p r i n c i p a l impact of g i n s i n M i s s i s s i p p i on ambient a i r q u a l i t y was p r i n c i p a l l y that of a nuisance. Improved cyclone c o l l e c t o r s and f i l t e r s were developed and used i n g i n s t o e l i m i n a t e a l l but t h e f i n e s t of p a r t i c u l a t e s r e l e a s e d by c o t t o n during g i n processing (5, J3, 8^, 9). Durrenberger (10, 11) i n 1973 s t u d i e d a i r b o r n e p a r t i c u l a t e s a t v a r y i n g d i s t a n c e s from g i n s i n Texas. He developed a p r e d i c t i o n equation f o r estimating the dust c o n c e n t r a t i o n i n a i r downwind from g i n s . The equation was based on g i n n i n g r a t e , f o r e i g n matter content of the c o t t o n as harvested, and took i n t o account the amount of emission c o n t r o l equipment i n use at the g i n . H i s study showed that the heavier p a r t i c u l a t e s r e l e a s e d i n t o the atmosphere f e l l to e a r t h near the g i n but that the f i n e r p a r t i c l e s were transported s e v e r a l hundred meters. Dust L e v e l s i n Cotton Gins A i r b o r n e dust c o n c e n t r a t i o n s i n s i d e Midsouth and Texas g i n s were measured by Wesley (12, JL3) i n 1972, 1973 and 1974 and a r e summarized i n Table I. The g i n s d i d not have the same hourly
Stripper
Stripper
Miss
Miss
TX
TX
1973
1973
1974
1974
1974
1974
3
4
5
6
7
8
b
a
Spindle
Miss
1972
2
Spindle
Spindle
Spindle
From Wesley ( 1 2 ) . n s = not sampled.
Ark
Ark
Spindle
Miss
1972
1
Spindle
Harvest method
Gin
High Low
High Low
High Low
High Low High Low
High Low
High Low
High Low
0.49 0.43
0.83 0.72
1.02 0.45 0.97 0.66
ns ns
1.07 0.44 3.41 2.04
1.13 0.49
0.53 0.32
0.84 0.50
3.67 1.54
0.98 0.37 3.78 1.82
0.59 0.13
0.76 0.07
0.33 0.20
0.43 0.32
0.50 0.30
2.53 1.21
0.97 0.15 5.02 1.98
0.51 0.23
0.92 0.08
0.94 0.14
R e s p i r a b l e Dust, mg/m^ Console L i n t cleaner Press
a
b
2.79 0.34
1.90 0.41
3.83 0.77
2.29 0.49 4.93 1.48
2.66 0.45
ns ns
ns ns
Console
1.94 0.45
1.28 0.80
ns ns
3.39 0.27 9.28 0.97
3.75 0.47
ns ns
ns ns
T o t a l Dust, mg/m^ L i n t cleaner
TABLE I Representative Dust L e v e l s at Three Locations W i t h i n Commercial Cotton Gins i n Arkansas, M i s s i s s i p p i , and Texas
0.96 0.26
1.23 0.29
2.99 0.62
3.49 0.24 6.09 2.58
2.49 0.23
ns ns
ns ns
Press
30
COTTON
DUST
processing c a p a c i t y , and the cottons ginned were d i s s i m i l a r i n v a r i e t y , production h i s t o r y , and method of harvest. The data l i s t e d represent high's and low's f o r i n d i v i d u a l measurements. L e v e l s of both t o t a l dust as measured using a high-volume a i r sampler and r e s p i r a b l e dust as measured using a l a r g e v e r t i c a l e l e u t r i a t o r are reported f o r three d i s t i n c t areas w i t h i n the same g i n . When the M i s s i s s i p p i g i n s a r e considered as a group, the l i n t c l e a n e r area g e n e r a l l y had the highest dust l e v e l , w h i l e the b a l i n g press and console areas had approximately the same dust c o n c e n t r a t i o n . The console area of the Arkansas g i n s g e n e r a l l y had the highest dust l e v e l , and the press area the lowest. The Texas g i n s handling s t r i p p e r - h a r v e s t e d c o t t o n were d u s t i e r than the M i s s i s s i p p i and Arkansas g i n s handling s p i n d l e picked c o t t o n . The lowest l e v e l s found i n the s t r i p p e r - c o t t o n g i n s were higher than the highest dust l e v e l s i n the g i n s processing s p i n d l e - p i c k e d c o t t o n . These data point out that the dust l e v e l v a r i e s w i t h l o c a t i o n i n s i d e g i n p l a n t s as w e l l as the method used to harvest the c o t t o n . Hughes (14) s t u d i e d dust l e v e l s i n a C a l i f o r n i a g i n i n 1978. He found w i d e l y v a r y i n g dust l e v e l s at both the b a l i n g press and g i n stand areas that were roughly i n the same range as i n Wesley's M i s s i s s i p p i study, Table I I . K i r k , Leonard, and Brown (15) d i d an e x c e l l e n t study of dust i n New Mexico g i n s i n 1973. They examined r o l l e r g i n s as w e l l as saw g i n s and found that a i r i n the g i n stand area was d u s t i e r than a i r near the b a l i n g press i n both kinds of g i n s . They a l s o found t h a t r o l l e r g i n s processing Pirna c o t t o n were c o n s i d e r a b l y more dusty than g i n s processing A c a l a (upland) s p i n d l e - p i c k e d c o t t o n , Table I I . A new g i n f o r ginning s p i n d l e - p i c k e d c o t t o n was constructed i n the M i s s i s s i p p i D e l t a i n 1977. The layout of the machinery, doors, and waste c o l l e c t i n g system was designed to reduce worker and community exposure to a i r b o r n e dust by o p t i m i z i n g f u n c t i o n a l area l o c a t i o n s w i t h respect to the p r e v a i l i n g winds from the southwest and northwest. Dust l e v e l s were measured i n t h i s g i n (16) during the peak of the ginning p e r i o d i n 1979, and were found to be: Ambient upwind, r e s p i r a b l e dust Ambient downwind, r e s p i r a b l e dust I n s i d e the g i n , r e s p i r a b l e dust a t Gin stands L i n t cleaners B a l i n g press
3
0.053 mg/m 0.791 mg/m
3
3
0.282 mg/m 0.354 mg/m 0.289 mg/m
3
3
I n s i d e the g i n , t o t a l dust a t G i n stands L i n t cleaners B a l i n g press
3
0.500 mg/m 0.801 mg/m 0.481 mg/m
3 3
3.
GRIFFIN
AND
COLUMBUS
31
Dust in Cotton Gins
TABLE I I Airborne Dust Concentrations i n Commercial Gins i n Four Geographic Areas and i n New Mexico From Two Types of Gins
State California
Texas
a
New M e x i c o
b c d
1978
Saw
Spindle
1975
b
New M e x i c o
a
Harvest method
1974
b
MS D e l t a
Year
Gin type
0
0
1973
1973
Saw
Saw
Saw
Roller
Stripper
Spindle
Spindle
Spindle
S e e L i t e r a t u r e C i t e d (14). S e e L i t e r a t u r e C i t e d (13). S e e L i t e r a t u r e C i t e d (15). n s = not sampled.
Location in gin
Dust c o n c e n t r a t i o n mg/m Respirable Total 3
Press--High Low
1.184 0.397
1.926 0.646
High Gin stands Low
1.639 0.347
2.234 0.552
Press High Low
4.16 1.87
ns ns
High Gin stands Low
3.02 2.60
ns ns
Press High Low
1.02 0.07
ns ns
High Gin stands Low
0.92 0.15
ns ns
Press Avg
0.56
1.02
Stand Avg
0.90
1.93
Press Avg
1.75
4.05
Stand Avg
2.85
6.51
d
32
COTTON
DUST
These data, when compared to data from the other g i n s f a l l w i t h i n the high and low v a l u e s reported f o r o l d e r g i n s , handling s i m i l a r types of c o t t o n . Thus, the low v a l u e s reported i n t h i s paper appear to be the r e s u l t of ginning r e l a t i v e l y c l e a n cottons or from c o t t o n ginned when ambient wind d i r e c t i o n was f a v o r a b l e , or both, r a t h e r than r e s u l t i n g from an i n t e n t i o n a l machinery layout p a t t e r n . In summary, dust l e v e l s i n g i n n e r i e s may c l u s t e r about a c e n t r a l v a l u e , but a c t u a l v a l u e s are h i g h l y dependent upon the n a t u r a l , and u s u a l l y u n c o n t r o l l a b l e , production and h a r v e s t i n g s i t u a t i o n that e x i s t s a t the time.
Composition of G i n Dust As c o t t o n i s brought under the unloading s u c t i o n telescopes at a g i n , one may observe i n the load of seed c o t t o n f o r e i g n m a t e r i a l such as l e a f p a r t s ; unopened whole b o l l s ; b o l l fragments; p i e c e s of f i e l d weeds, g r a s s e s , and v i n e s ; s o i l p a r t i c l e s ; and sometimes i n s e c t r e s i d u e s and evidence of f u n g a l / b a c t e r i a l i n f e c t i o n . Fragments of these m a t e r i a l s are c a r r i e d over i n t o the baled l i n t i n s p i t e of g i n e f f o r t s to remove them. There a r e s e v e r a l o p p o r t u n i t i e s i n the g i n n i n g system f o r p a r t i c l e s of these m a t e r i a l s to be r e l e a s e d i n t o the atmosphere along w i t h f u g i t i v e f i b e r s . Morey s (17) statement that c o t t o n dusts emitted during opening, cleaning,and carding of raw cottons i n t e x t i l e m i l l s should be r e l a t i v e l y r i c h i n b r a c t , l e a f and weed m i c r o p a r t i c u l a t e a p p l i e s e q u a l l y w e l l to dust i n g i n s . In h i s a n a l y s i s of p a r t s of mature c o t t o n p l a n t s , Brown (18) r e p o r t e d c o n s t i t u e n t s i n r o o t s , stem, l e a v e s , b o l l s , seed and l i n t . In Table I I I , I have l i s t e d h i s v a l u e s f o r leaves and l i n t which are among the p r i n c i p l e components of unginned c o t t o n . These data do not show the presence of crop p r o t e c t i o n or harvest a i d chemicals. Wesley and W a l l (19) c o l l e c t e d and analyzed a i r b o r n e dust samples c o l l e c t e d from three areas w i t h i n f i v e M i s s i s s i p p i g i n s i n 1975. The g e n e r a l composition of t h e i r samples are summarized i n Table IV. These data show the dust to be about 30 percent c e l l u l o s i c , the remainder being s o i l and other m a t e r i a l s . The q u a n t i t a t i v e elemental a n a l y s i s of t h e i r samples i s d e t a i l e d i n Table V. Although the percentages are d i f f e r e n t , the c o n s t i t u e n t s i n these samples of g i n dust are v e r y s i m i l a r to those l i s t e d by Brown (18) i n whole p l a n t p a r t s . None of the data presented have i d e n t i f i e d r e s i d u e s from i n s e c t i c i d e s or harvest a i d chemicals. This may be because they were not s p e c i f i c a l l y sought. 1
3.
GRIFFIN
AND
COLUMBUS
33
Dust in Cotton Gins
TABLE I I I Chemical A n a l y s i s of Leaf and L i n t P a r t s of Mature Cotton Plants' (percent dry b a s i s ) Constituent
Leaf
Lint
Nitrogen
2.25
0.18
Phosphoric a c i d
0.48
0.09
Potash
1.09
0.59
Lime
5.28
0.70
Magnesia
0.94
0.14
I r o n oxide
0.43
0.16
Soda
0.66
0.07
Sulphuric acid
1.05
0.09
Silica
1.70
0.07
Ash
12.55
1.25
Protein
14.06
1.12
Fiber
8.71
87.02
Fat
8.49
0.61
56.19
10.00
Carbohydrates a
A f t e r Brown ( 1 8 ) .
34
COTTON
DUST
Table IV Chemical Separation of Cotton Dust C o l l e c t e d i n M i s s i s s i p p i Gins, Crop of 1975 a
Material
Composition
|
Ash Protein Moisture Water s o l u b l e component A l c o h o l s o l u b l e component N o n c e l l u l o s e organic Cellulose Residual inorganic a
(percent)
32.9 11.8 3.4 12.6 1.7 24.7 30.5 27.1
A f t e r Wesley and Wall (19).
TABLE V Q u a n t i t a t i v e Elemental A n a l y s i s by X-ray Fluorescence of Cotton Dust C o l l e c t e d i n M i s s i s s i p p i Gins, Crop of 1975 Element Si K Al Ca Mg P Fe
Percentage 7.69 1.82 1.46 1.15 1.04 0.52 0.49
a
Element
Percentage
S CI Cu Ti Zn Mn
0.32 0.16 0.08 0.05 0.05 0.01
a
A f t e r Wesley and W a l l (19).
As pointed out e a r l i e r , a l l U.S. cotton i n commercial production i s now harvested by machines. The a p p l i c a t i o n of h a r v e s t - a i d chemicals t o cause the p l a n t s t o shed t h e i r leaves ( d e f o l i a t i o n ) o r t o k i l l and d r y t h e plant ( d e s i c c a t i o n ) are common p r a c t i c e s i n many areas. Chlorates and organic phosphates a r e popular d e f o l i a n t m a t e r i a l s and a r s e n i c a c i d i s commonly used as a d e s i c c a n t . P a g a n i n i (20) i n 1966 found a r s e n i c i n the a i r near cotton g i n s i n Texas i n concentrations of 0.01-141 ug/m a t d i s t a n c e s of 150 t o 8000 f e e t from t h e g i n . Schacht and L e P o r i (21) reported on chemical p r o p e r t i e s of cotton g i n waste from s i x gins i n Texas i n 1977. They included g i n s handling only d e s i c c a t e d s t r i p p e r - h a r v e s t e d and non-desiccated s p i n d l e harvested cotton. They observed a s t r i k i n g d i f f e r e n c e i n a r s e n i c l e v e l s i n g i n wastes from the two areas; the As l e v e l from the d e s i c c a t e d cottons was 0.02%, but was only 0.001% from the non-desiccated cottons (Table V I ) . 3
3.
GRIFFIN
AND COLUMBUS
35
Dust in Cotton Gins
TABLE V I Mean Values f o r Chemical Composition of Ginning Wastes at Six Texas Gins, Crop of 1977 Item Composition, percent a
1 5
Volatile Carbon Hydrogen Nitrogen Sulfur Oxygen and e r r o r A r s e n i c - i n areas using arsenical desiccants A r s e n i c - i n areas not using a r s e n i c a l desiccants
a
85 42 5.4 1.4 1.7 34.5 0.02 0.001
A f t e r Schacht and L e P o r i (21).
Seated 7 minutes a t 950°C.
Although a r s e n i c was not i n i t i a l l y reported i n the samples studied by Wesley and W a l l , re-examination of one of the samples did show i t to be present. The cotton from which t h i s sample came probably had not been d e s i c c a t e d ; the a r s e n i c could have had i t s o r g i n i n the s o i l from e a r l i e r days or as f i b e r r e s i d u e from chemical pest c o n t r o l during the present cotton-growing season. Present Status and Outlook We a r e p r e s e n t l y r e a d j u s t i n g our research program at the U.S. Cotton Ginning Laboratory a t S t o n e v i l l e , MS, to take advantage of newly developed r a p i d response instrumentation f o r measuring a i r b o r n e dust c o n c e n t r a t i o n s , as w e l l as the c o t t o n dust analyzer described by Baker (22). We are expanding cooperative r e l a t i o n s h i p s w i t h other USDA-ARS r e s e a r c h u n i t s to o b t a i n chemical and b i o l o g i c a l analyses h e r e t o f o r e u n a v a i l a b l e to us. We expect to continue our e f f o r t s to reduce a i r b o r n e dusts i n the v i c i n i t y of cotton g i n s , and t o i d e n t i f y and q u a n t i f y not only the elements present, but a l s o i d e n t i f y r e s i d u e s from growth r e g u l a t o r s , p e s t i c i d e s and h e r b i c i d e s as w e l l as d e s i c c a n t s and d e f o l i a n t s . This work w i l l i n c l u d e analyses of m a t e r i a l s remaining on the f i b e r s being baled f o r commercial use.
36
COTTON DUST
Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22.
HEW Publication No. (NIOSH) 1974, 75 (118), 1. Suta, B.E. SRI International, Menlo Park, CA, 1980, 1. USDA ESCE 1980, (84). U.S. Cotton Ginning Laboratory, USDA-SEA-ARS, Stoneville, MS Annual Report for FY 1967 and 1968. Alberson, D.M.; Baker, R.V. USDA ARS 42-103, 1964. Anderson, J.D.; Baker, R.V. USDA ARS-S-150, 1976. Baker, R.V.; Parnell, C.B., Jr. USDA ARS 42-192, 1971. McCaskill, O.L.; Wesley, R.A. USDA ARS-S-144, 1976. Wesley, R.A.; McCaskill, O.L.; Columbus, E.P. USDA ARS 42-167, 1970. Durrenberger, C. Texas Air Control Board Report. 1974. Durrenberger, C.J. Texas Air Control Board. 1975 Wesley, R. A. The Cotton Ginners Journal and Yearbook 1975, 43 (1), 51-53. Wesley, R. A. Cotton Dust Proceedings 1977, 21-24. Hughs, S. E . ; Urquhart, N.S.; Smith, D.W. Am. Soc. of Agr. Engr. Winter Meeting 1979, 79, (3553), 24. Kirk, I.W.; Leonard, C.G.; Brown, D.F. Trans, of the ASAE 1977, 20 (5), 962-68. Hicks, M.; Nevins, P. Environ. Control, Inc. Draft report, 1980. Morey, P.R. Special Session of Beltwide Cotton Production Research Conference 1977, p 4-6. Brown, H.B. "Cotton"; McGraw-Hill Book Co. New York, p 220. Wesley, R.A.; Wall, J.H. Am. Ind. Hyg. Assoc. J . 1978, 39, 962-69. Paganini, O. Texas State Dep. of Health, Austin, TX. 1965. Schacht, O.B.; LePori, W.A. The Cotton Ginners' Journal and Yearbook 1980, 48 (1), 27-36. Baker, R.V. ACS Symposium on OSHA Cotton Dust Standards, March 29-30, 1981, Atlanta, GA.
RECEIVED
December 15, 1981.
