Dermal Exposure Related to Pesticide Use - American Chemical Society

27 Evaluation of Fluorescent Tracer Methodology for Dermal Exposure Assessment 1

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RICHARD A. FENSKE , JOHN T. LEFFINGWELL , and ROBERT C. SPEAR Downloaded via UNIV OF CALIFORNIA SANTA BARBARA on July 10, 2018 at 05:03:25 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

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Department of Environmental Science, Cook College, Rutgers University, New Brunswick, ΝJ 08903 Department of Biomedical and Environmental Health Sciences, University of California, Berkeley, CA 94720

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The feasibility o f employing f l u o r e s c e n t t r a c e r s and video imaging a n a l y s i s to quan tify dermal exposure to p e s t i c i d e a p p l i c a t o r s has been demonstrated under realistic field conditions. S i x workers loaded a t r a c e r w i t h the organophosphate pesticide, diazinon, i n t o a i r b l a s t s p r a y e r s , and conducted normal dormant s p r a y i n g in pear orchards. They were examined p r i o r to and immediately a f t e r the a p p l i c a t i o n . UV-A illumination produced fluorescence on the skin surface, and the p a t t e r n of exposure was digitized w i t h a video imaging system. Q u a n t i f i a b l e l e v e l s of t r a c e r were detected beneath cotton c o v e r a l l s on five workers. The distribution of exposure over the body surface v a r i e d widely due to d i f f e r e n c e s i n p r o t e c t i v e c l o t h i n g use, work p r a c t i c e s and environmental c o n d i t i o n s . This assessment method produced exposure values at v a r i a n c e w i t h those c a l c u l a t e d by the traditional patch technique. T h e n e e d t o q u a n t i t a t i v e l y e v a l u a t e d e r m a l e x p o s u r e among pesticide a p p l i c a t o r s has been r e c o g n i z e d s i n c e a t l e a s t 1954 (1). The work o u t l i n e d here represents a new approach to t h i s problem and p r o v i d e s suggestions for further research i n this f i e l d of exposure assessment. The tracing o f d e r m a l d e p o s i t i o n among applicators by means of f l u o r e s c e n t compounds was f i r s t u n d e r t a k e n in 1979 (2). Since t h a t time an instrument capable of measuring fluorescence directly on t h e s k i n has been developed and t e s t e d . The d e t a i l s o f t h e instrumental design and t h e n a t u r e o f the f l u o r e s c e n t compound em ployed as a t r a c e r have been d i s c u s s e d elsewhere (3)· This paper r e p o r t s the r e s u l t s o f i n i t i a l f i e l d investi g a t i o n s w i t h the method. 0097-6156/85/0273-0377$06.00/0 © 1985 American Chemical Society

Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

378

DERMAL EXPOSURE RELATED TO PESTICIDE USE

The c o n c e p t u a l b a s i s o f t h i s t e c h n i q u e i s s t r a i g h t forward. A n o n - t o x i c f l u o r e s c e n t compound i s i n t r o d u c e d into a spray apparatus i n p r o p o r t i o n t o the pesticide being applied. Workers a r e asked t o conduct spray operations normally. Any c o n t a m i n a t i o n from m i x i n g and l o a d i n g , e q u i p m e n t a d j u s t m e n t o r s p r a y i n g i s e v i d e n c e d by t h e d e p o s i t i o n o f t r a c e r on t h e s k i n . Immediately following the spraying episode, t h e worker i s examined under long wave u l t r a - v i o l e t l i g h t i n o r d e r t o v i s u a l i z e t h e p a t t e r n of exposure on t h e body surface. The V i d e o Imaging Technique f o r Assessing Exposure, o r VITAE system, emp l o y s a t e l e v i s i o n camera i n t e r f a c e d w i t h a microcomputer to detect and q u a n t i f y f l u o r e s c e n c e on the skin. A standard curve relating l i g h t i n t e n s i t y t o amount of t r a c e r i s used t o determine t o t a l t r a c e r exposure. The ratio o f t r a c e r t o p e s t i c i d e i s e s t a b l i s h e d on t h e b a s i s of f i e l d s a m p l i n g , and t o t a l p e s t i c i d e e x p o s u r e r e p o r t e d . The i m p e t u s f o r t h i s s t u d y came f r o m a realization that t h e t r a d i t i o n a l p a t c h t e c h n i q u e (4) w a s inherently limited i n i t s a b i l i t y t o a c c u r a t e l y measure dermal exposure, and from t h e g r e a t p o t e n t i a l which a fluorescent t r a c e r methodology appeared t o h o l d . The a b i l i t y t o v i s u a l i z e exposure immediately provides v a l u a b l e q u a l i t a tive i n f o r m a t i o n regarding the exposure process. When combined w i t h a v i d e o image p r o c e s s i n g system which quant i f i e s fluorescence, the p o s s i b i l i t y of c a r e f u l l y characterizing dermal e x p o s u r e seemed w e l l w o r t h the effort involved. A t t h e o u t s e t i t was c l e a r t h a t t h e d e v e l o p m e n t o f a computer-based instrument and t h e use o f a surrogate compound ( t r a c e r ) w o u l d make t h e m e t h o d much more c o m p l e x than the t r a d i t i o n a l approach. Thus, the study has extended over s e v e r a l y e a r s , involving both laboratory and field tests. Appropriate fluorescent tracers were first screened, and their chemical and environmental c h a r a c t e r i s t i c s s t u d i e d . S i m u l t a n e o u s l y , t h e v i d e o image p r o c e s s i n g s y s t e m was d e s i g n e d a n d t e s t e d . S o f t w a r e was then developed t o run the system, and e v a l u a t i o n and quantification procedures established. Finally, the system was taken into the f i e l d to study applicators conducting routine spraying operations. Field

Study

Conditions

The f l u o r e s c e n t t r a c e r t e c h n i q u e was e m p l o y e d i n a n a p p l i c a t o r e x p o s u r e s t u d y i n L a k e C o u n t y , CA, i n J a n u a r y o f 1983. The f i e l d t r i a l was b a s e d a t t h e o f f i c e s o f t h e County Agricultural Commissioner and t h e U n i v e r s i t y of California Extension Service, approximately 200 miles north o f San F r a n c i s c o . The a g r i c u l t u r a l r e g i o n surrounding C l e a r L a k e was c h o s e n d u e t o t h e l i k e l i h o o d of r e c r u i t i n g owners o f s m a l l pear o r c h a r d s as s u b j e c t s . The study involved s i x applicators, and included a i r sampling, a modified v e r s i o n o f the dermal patch t e c h n i q u e , and t h e use o f a t r a c e r d u r i n g t h e s p r a y i n g o f


27.

Fluorescent

FENSKE ET AL.

Tracer

379

Methodology

the organophosphate, diazinon [0,0-diethyl 0-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate]. Field conditions w e r e s t a n d a r d i z e d as much as p o s s i b l e f o r t h e six subjects, and a r e s u m m a r i z e d i n T a b l e I .

Table

Field

Trial

Application Parameter

1

2

3

4

5

6

Tank

loadings

3

4

4

4

2

1

sprayed

3.75

4

4

4

2

1

500

500

500

500

500

500

400

500

500

500

500

500

20

20

20

20

10

1200

1200

1200

1200

600

300

152

130

102

129

73

48

Acres

I.

Worker

Tank s i z e (gallons) Gallons sprayed per acre Total diazinon sprayed (lbs) Total tracer sprayed (gms) Spraying time (minutes)

The major manner :

A p p l i c a t i o n Parameters

v a r i a b l e s were c o n t r o l l e d

in

the

5

following

Equipment: A l l subjects employed tractor-powered air blast sprayers. A l l of the s p r a y e r s were c a l i b r a t e d to produce a h i g h v o l u m e a p p l i c a t i o n o f e i t h e r 400 o r 500 g a l l o n s per a c r e . Activity: The subjects were owner-operators and conducted both t h e i r own m i x i n g / l o a d i n g and spraying. The m o n i t o r i n g p r o t o c o l d i d n o t d i s t i n g u i s h b e t w e e n t h e s e two activities. The p e s t i c i d e and t r a c e r were added sequentially to the spray tank, with the worker i n s t r u c t e d t o t r e a t b o t h c o m p o u n d s i n t h e same m a n n e r . Pesticide: S u b j e c t s were each s u p p l i e d w i t h f o u r 5 lb. bags o f 50% w e t t a b l e powder f o r m u l a t i o n diazinon. The spray s c h e d u l e recommended by t h e U n i v e r s i t y o f C a l i f o r nia R e s e a r c h E n t o m o l o g i s t f o r p e a r p s y l l a and San Jose s c a l e was 5 l b s . p e r a c r e , a n d was f o l l o w e d b y a l l s u b jects except W o r k e r #1. E i g h t g a l l o n s of dormant o i l were a l s o a p p l i e d to each a c r e . Fluorescent Tracer : The F l u o r e s c e n t W h i t e n i n g A g e n t , 4methyl-7-diethylaminocoumarin, was e m p l o y e d a s a t r a c e r . T h i s compound i s commonly u s e d i n c o m m e r c i a l p r o d u c t s and h a s u n d e r g o n e t o x i c i t y t e s t i n g (1) (j>) . A 300 gm b a g of tracer was a d d e d w i t h e a c h 5 l b . bag o f d i a z i n o n 50% WP Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.


380

( 1 1 3 4 gms a c t i v e i n g r e d i e n t ) , r e s u l t i n g i n a t r a c e r t a n k c o n c e n t r a t i o n o f 1 5 8 ppm, a n d a r a t i o o f 3 . 8 : 1 , pesticide: t r a c e r. Spray Period: S u b j e c t s w e r e a s k e d t o c o n d u c t f o u r comp l e t e spray cycles ( i . e . , four tank l o a d i n g s and sprayings). W o r k e r s #5 a n d #6 s p r a y e d f o r a s h o r t e r t i m e d u e to changes i n weather, a n d W o r k e r #1 made only three loadings due t o h i s d e c i s i o n t o spray h i g h e r concentrations. S p r a y t i m e s ranged from 40-152 m i n u t e s . Protective Clothing: The p e r s o n a l p r o t e c t i o n employed during t h e f i e l d t r i a l i s summarized i n Table I I . Resp i r a t o r s were used by a l l s u b j e c t s . Long s l e e v e cotton c o v e r a l l s and s h o r t s l e e v e c o t t o n T - s h i r t s were i s s u e d t o each s u b j e c t and were worn throughout t h e spray period. In some cases e x t r a s h i r t s and work pants were worn beneath t h i s c l o t h i n g . Weather: Most o f t h e s u b j e c t s took a very cautious a t t i t u d e toward wind c o n d i t i o n s . S p r a y i n g was n o t c o n d u c t e d u n l e s s t h e d a y was c a l m , and even then one o f t h e workers chose t o spray i n o n l y one d i r e c t i o n t o avoid drift. I n c r e a s i n g wind and t h e t h r e a t o f r a i n c u t s h o r t t h e s p r a y p e r i o d o f s u b j e c t s #5 a n d #6 o n t h e l a s t d a y o f the study. Materials

and Methods:

Environmental

Sampling

Environmental s a m p l i n g f o r t h e f i e l d t r i a l was g u i d e d b y three aims: 1) e s t a b l i s h m e n t o f e s t i m a t e s o f e x p o s u r e which allow comparison with other f i e l d s t u d i e s ; 2) d e termination o f l e v e l s o f p e s t i c i d e and t r a c e r i n the environment o f t h e worker; a n d 3) e v a l u a t i o n of the environmental stability of thetracer. The first a i m was a c c o m p l i s h e d by collecting p e r s o n a l a i r samples and employing a modified v e r s i o n o f the t r a d i t i o n a l patch technique. The second a i m r e q u i r e d a t t a c h i n g gauze monitors t o t h e spray r i g i n t h e v i c i n i t y of t h e worker. The f i n a l a i m i n v o l v e d spiking gauze m o n i t o r s w i t h known q u a n t i t i e s o f t h e t r a c e r a n d e x p o s i n g them to sunlight during the spraying episode. This c h a r a c t e r i z a t i o n of t h eenvironment o f t h eworker allowed estimation o f exposure independent o f t h e video imaging analysis, and provided information necessary f o rthe i n t e r p r e t a t i o n o f t h eVITAE system r e s u l t s . Air Sampling: P e r s o n a l a i r samples were c o l l e c t e d i n t h e b r e a t h i n g zone o f t h e worker f o r t h e e n t i r e s p r a y p e r i o d . A G i l i a n b a t t e r y p o w e r e d pump a t t a c h e d t o t h e b e l t was c o n n e c t e d t o a n o p e n - f a c e d 37mm c a s s e t t e w i t h a M i l l i p o r e filter, and t h e c a s s e t t e c l i p p e d t o t h e l a p e l of the coveralls. T h e pumps w e r e c a l i b r a t e d p r i o r t o a n d i m mediately after use.


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FENSKE ET AL.

Table

Fluorescent

I I .

Tracer

Personal

Protection During

P r o t e c t i v e G e a r w o r n by #2 #1

Body Part

baseball cap none

Head Face Hands Torso

(issued) (issued) Legs (issued) Feet Respiratory

rubber gloves thermal under wear coverall T-shirt thermal coverall rubber boots MSA dual cartridge

baseball cap eye glasses rubber gloves shirt + T-shirt coverall T-shirt jeans coverall rubber boots Pesticide dual cartridge

P r o t e c t i v e G e a r w o r n by #5 #4

Body Part Head Face Hands Torso

(issued) (issued) Legs (issued) Feet Respiratory

381

Methodology

Spray

Worker #3 hard hat face shield rubber gloves shirt + vest coverall T-shirt jeans coverall rubber boots MSA dual cartridge

Worker #6

plastic helmet face shield vinyl gloves none

hard h a t

hard hat

face shield polyeth gloves none

face shield rubber gloves shirt

coverall T-shirt none coverall plastic boots Pesticide dual cartridge

coverall T-shirt jeans coverall rubber boots Pesticide dual cartridge

T-shirt coverall T-shirt jeans coverall leather boots Pesticide dual cartridge


382


Personal Sampling: The dermal monitor employed is a modification of the t r a d i t i o n a l method of Durham and W o l f e (4), a n d was d e v e l o p e d a t t h e U n i v e r s i t y o f C a l i f ornia, Berkeley. The monitor c o n s i s t s of a solvente x t r a c t e d 1 2 - p l y s u r g i c a l g a u z e p a d ( 3 " χ 3")# b a c k e d by p o l y e t h y l e n e , and p l a c e d i n a p a p e r e n v e l o p e . The e n v e l o p e d e s i g n i n c l u d e s a 6 cm d i a m e t e r c i r c l e c u t o u t . Thus, t h e e x p o s e d g a u z e s a m p l i n g s u r f a c e i s 2 8 . 2 7 s q cm. When stapled t o g e t h e r t h i s a s s e m b l a g e becomes a s t u r d y unit, easily a t t a c h e d and removed f r o m a w o r k e r ' s c l o t h i n g or skin. Following a p r o t o c o l s i m i l a r to F r a n k l i n , et a l (2), and D a v i e s , e t a l (6), f o u r dermal m o n i t o r s were p l a c e d on e a c h w o r k e r , two on t h e o u t s i d e o f t h e c o v e r a l l , and two on the T - s h i r t beneath the c o v e r a l l in order to measure t h e amount o f p e s t i c i d e and tracer penetrating the outer garment. A l l o u t e r m o n i t o r s w e r e p l a c e d on t h e l e f t b r e a s t and r i g h t s h o u l d e r b l a d e ; a l l inner monitors w e r e p l a c e d on t h e r i g h t b r e a s t and l e f t s h o u l d e r b l a d e . Rig Samples : Three m o n i t o r s were a t t a c h e d to the top of the spray r i g ( i . e . , p a r a l l e l t o t h e g r o u n d ) a t t h e end n e a r e s t t h e t r a c t o r , a p p r o x i m a t e l y 150 cm f r o m t h e w o r k e r and 150 cm f r o m t h e t a n k opening for loading. This distance appeared s u f f i c i e n t to avoid contamination dur i n g m i x i n g and l o a d i n g . These s a m p l e s i n d i c a t e t h e l e v e l of p e s t i c i d e i n the environment of the worker, and pro vide a f u r t h e r measurement of the r a t i o of p e s t i c i d e to t r a c e r i n the a e r o s o l . Sun Samples: The f l u o r e s c e n t t r a c e r u s e d i n t h i s s t u d y can degrade when e x p o s e d t o d i r e c t s u n l i g h t (_3) . The e x t e n t o f t h i s d e g r a d a t i o n was m e a s u r e d b y p l a c i n g moni tors in the f i e l d . S i x monitors f o r each worker were spiked w i t h a m e a s u r e d amount o f t r a c e r i n acetonitrile just prior to each spray p e r i o d , and a l l o w e d to dry. Three of the m o n i t o r s were then p l a c e d i n d i r e c t s u n l i g h t i n an a r e a a d j a c e n t t o t h e s p r a y i n g , b u t w h e r e no expo sure to the spray would occur. The o t h e r t h r e e m o n i t o r s were n o t e x p o s e d t o s u n l i g h t and s e r v e d as c o n t r o l s . The time of s u n e x p o s u r e was n o t e d f o r t h e s p r a y p e r i o d of each worker. Field Blanks: Two f i e l d blanks f o r each worker were taken to the w o r k s i t e to monitor p o t e n t i a l sample con tamination. They were exposed i n the a r e a where samples w e r e p r e p a r e d and c o l l e c t e d , and t h e n h a n d l e d , s t o r e d and a n a l y z e d i n a manner i d e n t i c a l t o t h e o t h e r e n v i r o n m e n t a l samples. A l l values r e p o r t e d i n t h i s s t u d y have been adjusted for background l e v e l s of d i a z i n o n and tracer recovered from these samples. Analysis : A l l samples were p l a c e d lection, t r a n s p o r t e d f r o z e n to the i n a deep f r e e z e to await a n a l y s i s .

on d r y i c e upon col l a b o r a t o r y and p l a c e d The a i r and e n v i r o n -


27.

FENSKE ET AL.

Fluorescent

Tracer

Methodology

383

mental s a m p l e s were e x t r a c t e d and a n a l y z e d a c c o r d i n g to the procedures d e t a i l e d p r e v i o u s l y (3). Samples were p l a c e d i n 1 2 5 m l N a l g e n e b o t t l e s w i t h 30 m l acetonitrile (Baker " r e s i - a n a l y z e d " g r a d e ) and e x t r a c t e d on an o s c i l l a t i n g s h a k e r t a b l e f o r 90 m i n u t e s . The e x t r a c t i o n e f f i ciencies o f d i a z i n o n and t h e t r a c e r were 93% and 101%, respectively. D i a z i n o n s a m p l e s w e r e a n a l y z e d w i t h a T r a c o r 222 Gas Chromatograph equipped with a flame photometric d e t e c t o r i n t h e p h o s p h o r o u s mode. The d i a z i n o n s t a n d a r d e m p l o y e d was o b t a i n e d f r o m E P A , R e s e a r c h T r i a n g l e P a r k . The limit o f d e t e c t i o n o f t h e i n s t r u m e n t was 0.3 n g w i t h a maximum i n j e c t i o n v o l u m e o f 10 u l . S i n c e a l l e n v i r o n m e n t a l sam ples were extracted i n 30 m l o f s o l v e n t a n d were not c o n c e n t r a t e d , t h e s e n s i t i v i t y p e r s a m p l e was 900 ng. The e n v i r o n m e n t a l samples were a n a l y z e d f o r tracer w i t h a T u r n e r 430 S p e c t r o f l u o r o m e t e r a t f i x e d wavelengths ( e x c i t a t i o n = 356 nm; e m i s s i o n = 420 n m ) . Standards were interspersed with samples, and t h e amount of tracer present calculated by means o f a s t a n d a r d curve. The limit of d e t e c t i o n of the instrument f o r this compound was < 5 ppb, a l l o w i n g d e t e c t i o n o f l e v e l s a s l o w a s 150 ng p e r s a m p l e . Materials

and

Methods : Video

Imaging A n a l y s i s

Evaluation o f t r a c e r on t h e s k i n s u r f a c e was conducted with the VITAE system, following a protocol s i m i l a r to that described e l s e w h e r e (3). The system quantifies f l u o r e s c e n c e i n t e n s i t y i n the f o l l o w i n g manner: a tele vision camera scans the s u r f a c e a r e a of a body part 30 times per second. A video d i g i t i z e r i n the computer takes one of these scans, c o n v e r t s the analog camera output t o d i g i t a l v a l u e s o n t h e b a s i s o f a 16 l e v e l g r e y scale, a n d d i s p l a y s t h e i m a g e o n a TV m o n i t o r . The d a t a is then stored on d i s k and is available for later analysis. The l i g h t i n g s y s t e m e m p l o y e d c o n s i s t e d o f BLB bulbs (black l i g h t s ) with f i l t e r s . T h e i n t e n s i t y o f UV-A light to which s u b j e c t s w e r e e x p o s e d was e v a l u a t e d prior to e x a m i n a t i o n w i t h a UVX R a d i o m e t e r (UV P r o d u c t s ) . With a l i g h t - t o - s u b j e c t d i s t a n c e o f 90 cm, t h e m a x i m u m l o n g w a v e UV i l l u m i n a t i o n was 210 u w a t t s / s q cm. The r e l a t i v e s t a n dard deviation o f 49 r e a d i n g s t a k e n i n a 70 cm χ 70 cm r e g i o n was 4%. B o t h p r e - and p o s t - e x p o s u r e images were taken of a l l body r e g i o n s above the w a i s t f o r each sub ject, resulting i n a t o t a l o f 30 p a i r s o f v i d e o images per subject (Table I I I ) . The l e g s and t h e i n s i d e s of the u p p e r arms were o m i t t e d i n t h i s t r i a l due t o diffi culties in subject positioning. The camera-to-subject distance was v a r i e d b e t w e e n 70 a n d 80 cm, and a t times t h e c a m e r a was m o v e d up o r d o w n t o a c c o m m o d a t e t h e loca tion of the body p a r t . A f i x e d a p e r t u r e of f/1.4 was employed throughout the study. A s t a n d a r d t a r g e t was r e a d a t 1 0 5 cm ( f / 1 . 4 ) prior to and immediately f o l l o w i n g each examination period. Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.


384 Table

I I I .

Body Part

Body P a r t s f o r V i d e o # Images Recorded

H a n d s (1) F o r e a r m (2) U p p e r A r m (2)

4 8 6

Head

4

(1)

Upper Torso

(1)

4

Lower Torso

(1)

4

Imaging A n a l y s i s

Anatomical

Boundaries

up t o t h e w r i s t s w r i s t s t o t h e elbow elbow t o t h e shoulder ( e x c l u d e s i n s i d e s o f arms) i n c l u d e s neck s i d e s and back neck t o b r e a s t ( i n c l u d e s f r o n t o f neck) breast to waist

T h i s measurement s e r v e d as an i n d i c a t o r o f t h e s t a b i l i t y of t h e system t h r o u g h o u t t h e s i x d a y f i e l d t r i a l . Readings o f these t a r g e t s a r e expressed as i n t e g r a t e d i n t e n s i t y , or counts. T h e t w e l v e r e a d i n g s r a n g e d f r o m 6709 t o 7414 counts, w i t h a mean v a l u e o f 6986 counts, and a s t a n d a r d d e v i a t i o n o f 157 (RSD = 2 . 2 5 % ) . This low v a r i ability c a n be c o n s i d e r e d n e g l i g i b l e f o r purposes of exposure quantification. R e d u c t i o n a n d a n a l y s i s o f t h e v i d e o i m a g i n g d a t a was conducted i n the laboratory following the field trial. The steps i n v o l v e d i n t h e c a l c u l a t i o n o f exposure from video images have been d e t a i l e d elsewhere {3), and a r e summarized here. A v a r i a b l e background r e f l e c t a n c e from t h e s k i n i s commonly o b s e r v e d w i t h t h i s system. Images of t h e v a r i o u s body p a r t s must be r e c o r d e d p r i o r t o t h e worker's exposure t o provide b a s e l i n e data. Thus, t h e area o f i n t e r e s t f o r q u a n t i f i c a t i o n on t h e A f t e r image (post-exposure) i s o u t l i n e d and superimposed onto the Before image, and background variability eliminated. Images a r e then corrected f o r lens distortions and changes i n d i s t a n c e , and a d j u s t e d f o r t h e nonplanar c h a r a c t e r i s i t i c s o f t h e v a r i o u s body p a r t s . A standard curve developed i n the l a b o r a t o r y serves as t h e b a s i s f o r t r a n s f o r m i n g a d j u s t e d l i g h t i n t e n s i t y t o amount o f t r a c e r on t h e s k i n s u r f a c e . R a t i o s o f p e s t i c i d e t o t r a c e r based on evironmental samples a l l o w c a l c u l a t i o n o f pesticide exposure. Laboratory s t u d i e s have demonstrated that p e s t i c i d e s a n d t r a c e r compounds p e n e t r a t e c o t t o n c o v e r a l l f a b r i c a t d i f f e r e n t r a t e s (3). Thus, an e m p i r i c a l penet r a t i o n f a c t o r o f 3.4:1 ( p e s t i c i d e t o t r a c e r ) i s e m p l o y e d in the final calculation o f exposure f o r protected regions. Results

and D i s c u s s i o n :

Environmental

Sampling

Air Samples: A i r s a m p l i n g d a t a p r o v i d e d t h e most d i r e c t means o f comparing l e v e l s of p e s t i c i d e i n t h e workplace from this study with those i n previous ones. The sampling d e v i c e s employed a r e very c l o s e t o s t a n d a r d , and Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

27.

FENSKE ET AL.

Fluorescent

Tracer

385

Methodology

the procedures f o r determining p o t e n t i a l exposure explic i t and g e n e r a l l y u n i f o r m . The r e s u l t s f r o m a i r samples in this study are presented i n Table IV. Four of the workers had s i m i l a r potential respiratory exposure, ranging from 8.6 t o 30 ug/cu meter. The sample of worker #6 h a d no detectable level of pesticide, p r e s u m a b l y due t o h i s s p r a y i n g o n l y one t a n k . The p o t e n tial e x p o s u r e o f w o r k e r #1 was n e a r l y a n o r d e r o f m a g n i tude greater than the other s u b j e c t s . A l l s u b j e c t s wore d u a l c a r t r i d g e , half-mask r e s p i r a t o r s d u r i n g s p r a y i n g , so l i t t l e i f any r e s p i r a t o r y exposure a c t u a l l y o c c u r r e d .

Table

IV.

A i rSampling

Results

Worker #

Time Spraying hrs

diazinon Concentration ug/cu meter

Potential Resp Exposure ug/hr

1 2 3 4 5

83 141 102 129 73

202.11 30.39 8.55 23.37 14.99

351.7 52.9 14.9 40.7 26.1

* Assumes a t i d a l volume o f 1740 l i t e r s A l l w o r k e r s wore r e s p i r a t o r s .

per hour.

In a p r e v i o u s a p p l i c a t o r s t u d y (2), a range o f 20110 u g / c u m e t e r was o b s e r v e d . The e x p o s u r e r a n g e o f 8.6202 u g / c u m e t e r i n t h i s s t u d y i s b r o a d e r , but of similar magnitude. Data from W o l f e e t a_l ( 7 - 8 ) i n d i c a t e an exposure range o f 6-167 u g / c u m e t e r , quite similar to levels recorded i n this study. Based on a i r s a m p l i n g , then, exposures appear t o be w i t h i n a normal range f o r mixer/loader/applicators employing a i r blast spraying equipment. Sun Samples : The c o m p a r i s o n o f e x p o s e d s p i k e d samples w i t h c o n t r o l s a l l o w s d e t e r m i n a t i o n o f t h e amount o f tracer lost during a t y p i c a l spray episode, and c a l c u l a t i o n of a c o r r e c t i o n f a c t o r f o r t h e e n v i r o n m e n t a l samples of each worker. V a r i a b i l i t y among t h r e e r e p l i c a t e s a m p l e s w a s l o w , w i t h r e l a t i v e s t a n d a r d d e v i a t i o n s l e s s t h a n 5%. S i n c e s u n l i g h t i n t e n s i t y and o t h e r e n v i r o n m e n t a l factors v a r i e d c o n s i d e r a b l y from day t o day and worker t o w o r k e r , it was n o t p o s s i b l e t o c a l c u l a t e a r a t e o f d e g r a d a t i o n . The l o s s o f t r a c e r r a n g e d f r o m 7% t o 2 2 % , w i t h approximately 10-15% l o s t i n two h o u r s . These r e s u l t s were q u i t e s i m i l a r to those observed i n c o n t r o l l e d studies of t r a c e r s t a b i l i t y (3). The p e r c e n t l o s s d u r i n g t h e s p r a y episode i s employed t o c o r r e c t f o r l o s s from t h e r i g and p e r s o n a l samples of each worker.


386


Rig Samples: Samples a t t a c h e d t o t h e spray r i g during the application p r o v i d e an i n d i c a t i o n of the aerosol c o n c e n t r a t i o n o f t h e two compounds i n t h e v i c i n i t y o f t h e worker. R e s u l t s a r e p r e s e n t e d i n T a b l e V. Mean p e s t i cide l e v e l s r a n g e f r o m 1.3 t o 4 5 . 2 3 u g / s q cm, a n d m e a n t r a c e r l e v e l s f r o m 0.49 t o 1 7 . 3 4 u g / s q cm. Analysis of

Table

V.

Exposure L e v e l s based on R i g Samples ( a l l v a l u e s i n m i c r o g r a m s / s q cm)

worker

mean diazinon

std dev

1 2 3 4 5 6

6.28 45.20 1.29 44.70 19.28 1.86

0.3 1.7 0.3 1.7 2.6 0.3

Note:

mean tracer 0.97 17.34 0.22 9.70 3.36 0.49

std dev

Ratio d:t

0.1 2.2 0.05 1.7 0.4 0.1

6.5 2.6 5.9 4.6 5.7 3.8

Ν = 3 i n a l lc a s e s

these v a l u e s by l i n e a r r e g r e s s i o n r e v e a l s a h i g h l ys i g ( r = 0.92, nificant c o r r e l a t i o n of t r a c e r and p e s t i c i d e ρ < .00001, η = 1 8 ) . The r e l a t i v e l y h i g h l e v e l s o f t r a cer recovered from t h e samples o f Worker #2 tend to reduce the linearity of this relationship. I f h i s data i s omitted from t h e a n a l y s i s t h e c o r r e l a t i o n i s improved (r = 0.984, ρ < .000001, η = 1 5 ) . T h e s e same r e l a t i o n ships a r e a l s o e v i d e n t from t h e r a t i o s o f p e s t i c i d e to t r a c e r shown i n t h e t a b l e . The r a n g e o f r a t i o s i s 2.61 t o 6.47. I f W o r k e r #2 i s e x c l u d e d , however, t h e range narrows markedly (3.80-6.47). I t i s n o t a p p a r e n t why t h e concentration of tracer on t h e s p r a y r i g m o n i t o r s of Worker #2 w a s e l e v a t e d r e l a t i v e t o t h e o t h e r subjects. I t i s p o s s i b l e t h a t t h e samples r e c e i v e d d i s p r o p o r t i o n a t e t r a c e r exposure d u r i n g mixing and l o a d i n g . I t s h o u l d be noted from Table V t h a t four o f t h e s i xc a l c u l a t e d s t a n dard r a t i o s a r e h i g h e r t h a n t h e 3.8:1 r a t i o o f t h e two compounds when introduced into the spray tank. These r e s u l t s i n d i c a t e a lower water s o l u b i l i t y f o r t h e t r a c e r than f o r t h e w e t t a b l e powder f o r m u l a t i o n of diazinon. This finding was c o r r o b o r a t e d by h i g h r a t i o s found i n samples o f t h e tank mix taken p r i o r t o s p r a y i n g . The ratio o f p e s t i c i d e t o t r a c e r i s an essential calibration factor f o r t h e VITAE system's exposure assessment. The r a t i o s d e r i v e d from t h e r i g samples a r e mean values o f three samples, and a r e thus t h e most statistically reliable indicators of the aerosol ratio among t h e m e a s u r e m e n t s t a k e n . In this study, therefore, these r a t i o s a r e employed t o t r a n s f o r m t r a c e r t o p e s t i cide. F u r t h e r i n v e s t i g a t i o n w i l l be n e c e s s a r y t o d e t e r m i n e how b e s t t o d e f i n e t h e s e v a l u e s .


27.

FENSKE ET AL.

Fluorescent

Tracer

387

Methodology

Personal Samples: D a t a f r o m t h e g a u z e p a t c h e s on t h e outside of the coveralls, and on t h e T - s h i r t i m m e d i a t e l y beneath the coveralls are presented i n Table VI with values e x p r e s s e d a s m i c r o g r a m s p e r s q cm o f g a u z e moni tor. Consistent with t h e data from t h e r i g samples, Workers #2, #4, a n d #5 s h o w r e l a t i v e l y h i g h l e v e l s of t r a c e r a n d p e s t i c i d e , w h i l e W o r k e r s #3, a n d #6 r e v e a l l o w levels. Worker #1 i s a n o m a l o u s , i n that h i s personal samples are relatively high, whereas t h e r i g samples p o i n t toward a moderate exposure.

Table

E x p o s u r e L e v e l s based on P e r s o n a l ( a l l v a l u e s i n m i c r o g r a m s / s q cm) chest Τ

work #

outer D*

chest T*

inner D

1 2 3 4 5 6

12.45 11.94 1.36 11.39 4.23 .53

6.83 7.20 .19 1.70 .49 .07

1.10

.21 .24

.01

.28

— —

— —

— — —

m i s s i n g v a l u e s were l e s s values D = diazinon, Τ = tracer

Note: *

VI.

outer D

back Τ

.99 3.40 .88 6.30 1.93 .54

.68 .62 .13 .54 .17 .08

than

2 times

Samples

inner D

back Τ

.04 .04

—

.12 05

— field

— blank

I n a c c o r d w i t h many p r e v i o u s f i e l d o b s e r v a t i o n s , t h e patches placed on t h e c h e s t o f f i v e o f t h e s i x w o r k e r s are m a r k e d l y h i g h e r than t h o s e on t h e b a c k . Such dif ferential e x p o s u r e c a n be t e n t a t i v e l y a t t r i b u t e d t o two factors: c o n t a m i n a t i o n o f t h e samples d u r i n g m i x i n g and loading, and the forward motion o f the worker during s p r a y o p e r a t i o n s c a u s i n g g r e a t e r d e p o s i t i o n on t h e front of t h e body. The levels beneath t h e c o v e r a l l s were t o o low t o q u a n t i f y i n most c a s e s . Four workers appear t o have had penetration o f low l e v e l s o f p e s t i c i d e or t r a c e r . Only W o r k e r #1, w h o s e o u t e r c h e s t p a t c h i s a l s o h i g h , a p p e a r s to have been s i g n i f i c a n t l y exposed beneath t h e coveralls based on t h e s e d a t a (i.e., p e s t i c i d e exposure > 1 ug/sq cm) . The p e r s o n a l s a m p l e s o n t h e c h e s t a n d b a c k a l l o w an estimate of pesticide e x p o s u r e based on the standard technique o f e x t r a p o l a t i n g from p a t c h t o t o t a l body r e gion. The s t a n d a r d method o n l y considers unprotected regions o f t h e body t o be exposed. In this case, only the head and neck o f t h e workers a r e u n p r o t e c t e d , and i n f o u r o f s i xcases face s h i e l d s were worn. Thus, beyond a comparison o f h e a d a n d n e c k e x p o s u r e f o r w o r k e r s #1 a n d #2, i t i s n o t c l e a r how t h e p a t c h t e c h n i q u e could be applied i n this study. Later i n t h i s paper the patch data will be e m p l o y e d t o make t h i s comparison. These Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

388


e x p o s u r e v a l u e s w i l l t h e n be compared w i t h from t h e video imaging a n a l y s i s . Results

and D i s c u s s i o n :

Video

Imaging

those

derived

Analysis

The Before and A f t e r v i d e o images f o r each worker were analyzed by t h e VITAE system t o determine t h e e x t e n t of exposure. Results a r epresented i n Table V I I . Workers # 3 , # 4 , # 5 , a n d #6 e x h i b i t o n l y m i n o r e x p o s u r e . I t should be r e c a l l e d t h a t a l l o f these w o r k e r s wore f a c e shields throughout t h e study period, and two sprayed f o r r e l a tively short periods.

Diazinon Exposure* Table VII. ( a l l values in micrograms) Body Parts**

1

2

W o r k e r No. 4 3

5

6

Hands LF Arm RF A r m LU A r m RU A r m Torso Head

551.6 1014.3 1536.6 329.8 400.2 631.3 995.7

118.1 61.2 0 11.6 56.2 94.5 146.2

212.3 0 0 0 0 0 0

99.8 0 127.0 0 0 0 35.9

0 0 0 0 130.6 0 115.0

0 55.8 0 0 0 0 0

TOTAL

5459.2

487.8

212.3

262.7

245.6

55.8

F l u o r e s c e n t t r a c e r exposure values have been a d j u s t e d by r a t i o o f d i a z i n o n to t r a c e r f r o m T a b l e V. ** R e g i o n s p r o t e c t e d b y c o v e r a l l s h a v e a l s o b e e n a d j u s t e d by a c l o t h i n g p e n e t r a t i o n f a c t o r o f 3.4. F o r W o r k e r s #1 a n d #2 t h e p e n e t r a t i o n f a c t o r h a s b e e n a p p l i e d t o t h e c h e s t b u t n o t t o t h e neck which r e mained unprotected.

*

T h e h a n d e x p o s u r e o f W o r k e r #3 i s u n d o u b t e d l y d u e t o his unique p r a c t i c e o f mixing and l o a d i n g w i t h gloves on, but s p r a y i n g w i t h no g l o v e s . His cautious practice of spraying i n o n l y one d i r e c t i o n t o a v o i d d r i f t appears t o have eliminated exposure t o the aerosol itself. The detection o f e x p o s u r e t o t h e f o r e a r m s o f w o r k e r s #4 a n d #6 c o r r o b o r a t e s v i s u a l o b s e r v a t i o n s . I t was n o t e d d u r i n g examination that a ring of diffuse fluorescence extended completely around t h e forearms, approximately 1 0 cm a b o v e the w r i s t s . Discussion with these workers revealed that the exposure ocurred j u s t a t t h e t o p o f t h e rubber gloves which they a l l employed. Since the coverall sleeves a r e n o t s e c u r e d i n a n y w a y , i t a p p e a r s t h a t t h i s e x p o s u r e may be d u e t o movement o f t h e g l o v e s a n d c o v e r a l l s a t this j u n c t i o n , rather than t h e r e s u l t o f c l o t h i n g p e n e t r a t i o n . The c a u s e o f t h e u p p e r a r m e x p o s u r e o f w o r k e r #5 i s n o t e v i d e n t , b u t may h a v e r e s u l t e d f r o m c o n t a c t w i t h c o n t a m i nated equipment. Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

27.

FENSKE ET AL.

Fluorescent

Tracer

Methodology

389

Exposure a t t h e base o f t h e neck o f Worker #4 w a s apparent during the examination. I t appeared as a high l i g h t i n t e n s i t y spot o f c i r c u l a r shape. The w o r k e r s u g gested d u r i n g d i s c u s s i o n t h a t t h e p l a s t i c helmet he wore d u r i n g a p p l i c a t i o n may h a v e c o l l e c t e d t h e a e r o s o l a n d a l lowed i t t o d r i p onto h i s back. W h i l e w o r k e r s #4 a n d #5 received exposure t o t h e head, only deposition to the sides of the face occurred. In fact, thepoint just i n front of the ear a t which the face s h i e l d s ended was clearly demarcated. Thus, t h e face s h i e l d s appear to have b e e n v e r y e f f e c t i v e i n r e d u c i n g a n d i n some cases e l i m i n a t i n g f a c i a l exposure. Quantifiable l e v e l s o f t r a c e r were d e t e c t e d on a l l b o d y p a r t s o f W o r k e r #1, a n d i n 25 o f 30 v i e w s . B a s e d on data i n Table V I I , the highest levels occurred on t h e forearms. I t i slikely, however, that exposure t o the head was g r e a t e r t h a n t h e s e f i g u r e s r e f l e c t . As noted previously, a f i x e d f / 1 . 4 a p e r t u r e was e m p l o y e d throughout the study. L a t e r a n a l y s i s o f t h e images revealed t h a t a s i g n i f i c a n t number o f p i x e l s f r o m t h e h e a d images were a s s i g n e d t h e maximum g r e y l e v e l o f 1 5 , indicating detector saturation. Considering the extremely high exposure which t h i s worker received t o t h e face, i ti s likely t h a t q u e n c h i n g a l s o came i n t o p l a y , contributing to an a r t i f i c i a l l y low value. These f a c t o r s d i d not appear t o o b t a i n f o r any o f t h e o t h e r images examined. Worker #2 e x h i b i t s the pattern of exposure which might have been p r e d i c t e d f o r a l l workers. The exposed region o f t h e head (no f a c e s h i e l d ) was h i g h e s t . The hands were a l s o h i g h , despite the use of gloves. However, elevated l e v e l s were a l s o d e t e c t e d beneath prot e c t i v e c l o t h i n g . S i n c e t h i s worker wore a f l a n n e l s h i r t and T-shirt i n addition to the T-shirt and c o v e r a l l s issued, i t was m o s t s u r p r i s i n g t o d e t e c t e x p o s u r e t o t h e chest. The v a l u e f o r t o r s o e x p o s u r e i n t h e t a b l e i n cludes both a p r o t e c t e d region (chest) and an exposed region (front of neck). Chest exposure alone accounted f o r 78 u g o f t h e 94 u g e x p o s u r e . The c a l c u l a t i o n o f e x p o s u r e b a s e d o n t h e p a t c h t e c h nique t r a d i t i o n a l l y employs t h e s i m p l i f y i n g assumption that c l o t h i n g p e n e t r a t i o n does n o t o c c u r , o r does n o t contribute s i g n i f i c a n t l y t o t o t a l exposure. Based on t h e f l u o r e s c e n t t r a c e r d a t a i t seems r e a s o n a b l e t o a r g u e t h a t this a s s u m p t i o n may b e i n a p p r o p r i a t e . Table VIII pres e n t s t h e p e r cent o f exposure o c c u r r i n g on both exposed and protected regions. Not s u r p r i s i n g l y , the patterns are h i g h l y v a r i a b l e as they a r e a f f e c t e d by both protective c l o t h i n g and work p r a c t i c e s . F o r t h e two workers w i t h e x p o s u r e t o n e a r l y a l l body r e g i o n s , p r o t e c t e d a r e a s accounted f o r 4 2 % (#2) a n d 7 1 % (#1) o f t o t a l exposure. In some c a s e s h a n d s may a c c o u n t f o r a l l e x p o s u r e ( # 3 ) , while i n o t h e r s t h e y may r e p r e s e n t a relatively small contribution. The c a l c u l a t i o n o f exposure by t h e p a t c h technique a l s o assumes t h a t d e p o s i t i o n o f p e s t i c i d e i s u n i f o r m over


390


Table

Region

Per

VIII.

1

Hands Head Coverall Protected

10 19 71

Cent of Exposure

2

3 24 33 42

100 0 0

to Body

W o r k e r No. 4 38 14 48

Regions

5

6

0 47 53

0 0 100

each body p a r t r e p r e s e n t e d by a p a t c h . It is evident from q u a l i t a t i v e e x a m i n a t i o n o f t h e w o r k e r s and recorded images that the d i s t r i b u t i o n of exposure over a given body r e g i o n ( e . g . , head, hands, forearm) i s not uniform. Such an e x p o s u r e p a t t e r n w o u l d c l e a r l y be an exception. T h e m o r e common p a t t e r n i s t h e a p p e a r a n c e o f a " h o t s p o t " a d j a c e n t t o a r e a s w i t h l i t t l e o r no e x p o s u r e . Thus, the e x t r a p o l a t i o n step i n standard exposure c a l c u l a t i o n s may underestimate exposure i f the p a t c h does not r e p r e s e n t a high exposure spot, but would o v e r e s t i m a t e exposure i f such a spot h i t the patch. Since the p a t t e r n s of exposure a r e h i g h l y v a r i a b l e and h a v e n o t been w e l l characterized, t h e r e d o e s n o t a p p e a r t o be any means o f d e t e r mining a priori where t o p l a c e a p a t c h t o s e r v e as a r e p r e s e n t a t i v e sample o f a body r e g i o n . As methods of exposure estimation, neither the f l u o r e s c e n t t r a c e r t e c h n i q u e nor the p a t c h t e c h n i q u e have been v a l i d a t e d . N e v e r t h e l e s s , i t w o u l d be e n c o u r a g i n g i f a comparison of e s t i m a t e s b y t h e two methods yielded roughly equivalent results. The o n l y b o d y r e g i o n which can be r e a s o n a b l y compared i s the head, as the patch m e t h o d a s s u m e s no c l o t h i n g p e n e t r a t i o n , a n d no h a n d w a s h was conducted i n t h i s study. Furthermore, four of the s i x w o r k e r s m u s t be e x c l u d e d , as t h e y wore f a c e s h i e l d s . Thus, t h e o n l y c o m p a r i s o n a v a i l a b l e i s t h e head and neck e x p o s u r e o f w o r k e r s #1 a n d #2. These data are presented i n Table IX. F o l l o w i n g t h e p r o t o c o l o u t l i n e d by Durham and Wolfe (£) a n d D a v i s (£) , t h e amount of diazinon recovered from t h e d e r m a l m o n i t o r on t h e c h e s t s o f the two w o r k e r s i s e m p l o y e d t o c a l c u l a t e e x p o s u r e t o t h e f a c e and f r o n t of neck. A s i m i l a r p a t c h on t h e b a c k allows c a l c u l a t i o n of exposure to the back of the neck. Exposure f o r t h e h e a d a n d n e c k o f w o r k e r #1 a p p e a r s to be 1 0 2 6 u g b y t h e t r a c e r m e t h o d . The e s t i m a t i o n of exposure for t h e s e same a r e a s d e r i v e d from the patch t e c h n i q u e i s 10,069 ug, o r 10 t i m e s g r e a t e r . The p a t c h estimate of 9 9 2 6 u g f o r w o r k e r #2 i s q u i t e similar to that of #1, w h i l e here the t r a c e r e s t i m a t e i s a much l o w e r 163 u g . The c u r r e n t l a c k o f any means o f o b t a i n i n g a " t r u e " v a l u e f o r exposure independent of t h e s e methods allows only i n f o r m e d s p e c u l a t i o n as t o w h i c h of these a p p r o a c h e s i s more c o r r e c t .


27.

FENSKE ET

AL.

Table

Work No.

1

2

Fluorescent

391

Methodology

IX. Dermal Exposure E s t i m a t i o n P a t c h and T r a c e r T e c h n i q u e s Surface Area s q cm

Body Part

Tracer

Face Back Neck F r o n t Neck

Face Back Neck F r o n t Neck

* Head r e g i o n f o r back of neck.

650 110 150

650 110 150

Patch Exposure u g / s q cm 12.45 0.99 12.45

Calculated Exposure ug/part

by

Tracer Exposure ug/part 996*

8092 109 1868

30

Total

10069

1026

11.94 3.40 11.94

7761 374 1791

146

Total

9926

163

tracer technique

includes

17

sides

and

Although the accuracy of the methods remains in question, one would expect each technique to provide reasonable comparative exposure estimates w i t h i n a study. Based on v i s u a l observations of the t r a c e r there is a clear d i f f e r e n c e between f a c i a l exposure t o t r a c e r for W o r k e r s #1 a n d #2. S u c h a d i f f e r e n c e i s c o r r o b o r a t e d by personal a i r sampling data, where these workers d i f f e r e d by n e a r l y an o r d e r o f m a g n i t u d e . A similar difference is r e f l e c t e d i n the t r a c e r exposure v a l u e s , w h i l e the patch technique m a k e s no d i s t i n c t i o n i n t h e e x p o s u r e o f these two subjects. Such comparisons are a t t h i s stage only s u g g e s t i v e , and w i l l r e q u i r e f u r t h e r i n v e s t i g a t i o n . Directions

for Future

Research

The f l u o r e s c e n t t r a c e r t e c h n i q u e a p p e a r s t o h o l d a p o t e n tial for p r o v i d i n g f a r more d e t a i l e d information concerning the magnitude and distribution of pesticide exposure than e x i s t i n g techniques. This i n i t i a l field trial also i l l u s t r a t e s many o f t h e c o m p l e x i t i e s o f the method. The q u a n t i t a t i v e r e l a t i o n s h i p o f t h e pesticide and tracer as t h e y a r e d e p o s i t e d on t h e skin surface n e e d s t o be d e t e r m i n e d w i t h a h i g h e r d e g r e e o f accuracy. A more careful d e t e r m i n a t i o n of the r a t i o of the two compounds i n an a e r o s o l , and o f t h e c h e m i c a l s ' a b i l i t y t o penetrate v a r i o u s types of f a b r i c i s clearly required. Further comparative studies employing the tracer and patch techniques would c l a r i f y the s t r e n g t h s and weakn e s s e s o f t h e s e two a p p r o a c h e s . Quantification of e x p o s u r e by means o f the VITAE system also requires refinement, p a r t i c u l a r l y i n regard to the c h a r a c t e r i z a t i o n of v a r i a b l e background l e v e l s in pre-exposure images. A s o l u t i o n t o t h i s p r o b l e m may l i e Honeycutt et al.; Dermal Exposure Related to Pesticide Use ACS Symposium Series; American Chemical Society: Washington, DC, 1985.

392

D E R M A L

E X P O S U R E

R E L A T E D

T O

P E S T I C I D E

U S E

in an improved l i g h t i n g / d e t e c t o r / f i l t r a t i o n s y s t e m . In a d d i t i o n , t h e problems o f d e t e c t o r s a t u r a t i o n and quenching currently l i m i t the accuracy o f t h e method. In general, such overloading of the s k i n surface with f l u o r escent m a t e r i a l c a n be a v o i d e d by c o n t r o l l i n g t h e amount of tracer introduced into the spraying system. I t appears that r e l a t i v e l y high l e v e l s of t r a c e r are necessary to detect protective clothing penetration, while much l o w e r l e v e l s w o u l d be a d e q u a t e t o m o n i t o r d e p o s i t i o n on exposed skin surfaces. A series of range-finding studies under controlled conditions could lead t o an appropriate r e s o l u t i o n of t h i s problem. Leaving s u c h r e f i n e m e n t s a s i d e f o r a moment, i t i s c l e a r t h a t t h e t r a c e r t e c h n i q u e a s now p r a c t i c e d p r o v i d e s an i n v e s t i g a t o r with a powerful qualitative tool for c h a r a c t e r i z i n g dermal exposure, and f o r d e v e l o p i n g recommendations c o n c e r n i n g p r o t e c t i v e c l o t h i n g use and changes i n work p r a c t i c e s . F u r t h e r , the worker education potent i a l o f t h i s a p p r o a c h c a n n o t be o v e r s t a t e d . The v i s u a l ization of exposure allows workers t o p a r t i c i p a t e i n their own e v a l u a t i o n . I n many i n s t a n c e s t h e y come to recognize f o r the f i r s t time the nature of the hazard which they face i n t h e i r day t o day work, a n d we have seen marked changes i n behavior l i t e r a l l y o v e r n i g h t . As a s i m p l e a n d i n e x p e n s i v e means o f e v a l u a t i o n , i t i s h o p e d that t h i s a p p r o a c h w i l l be adopted i n t h e agricultural workplace despite the refinements required f o r q u a n t i t a tive analysis. Nontechnical

Summary

The u s e o f f l u o r e s c e n t compounds as t r a c e r s of dermal exposure among p e s t i c i d e a p p l i c a t o r s has been tested under normal working c o n d i t i o n s . Six applicators introduced a Fluorescent Whitening Agent i n t o their spray tanks with the organophosphate p e s t i c i d e , d i a z i n o n . They were e x a m i n e d u n d e r l o n g wave u l t r a - v i o l e t l i g h t (black light) after spraying to v i s u a l i z e the pattern of expos u r e on t h e s k i n s u r f a c e . The f l u o r e s c e n c e was quantified b y means of the Video Imaging Technique f o r A s s e s s i n g Exposure, o r VITAE system. This system employs a television camera as a d e t e c t o r , and d i g i t i z e s the v i d e o s i g n a l b y means o f a microcomputer. Quantifiable levels o f t r a c e r were d e t e c t e d beneath t h e c o t t o n c o v e r a l l s of f i v e workers. The d i s t r i b u t i o n o f e x p o s u r e o v e r the body s u r f a c e v a r i e d w i d e l y due to differences i n p r o t e c t i v e c l o t h i n g u s e , work p r a c t i c e s and e n v i r o n m e n t a l conditions. Quantification of exposure with this technique i s subject to further refinements. Qualitative assessment has proven very s u c c e s s f u l i n regard t o worker education and t h e e v a l u a t i o n o f p r o t e c t i v e c l o t h i n g performance.


27.

FENSKE ET AL.

Fluorescent

Tracer

Methodology

393

Acknowledgments This work was i n i t i a l l y f u n d e d by t h e C a l i f o r n i a State Department o f I n d u s t r i a l R e l a t i o n s (Contract N o . 4-6141), and was s u b s e q u e n t l y s u p p o r t e d by t h e N a t i o n a l I n s t i t u t e for O c c u p a t i o n a l S a f e t y a n d H e a l t h ( G r a n t N o . 1 R 0 1 OH 01234-01A1) and the E n v i r o n m e n t a l P r o t e c t i o n Agency ( C o o p e r a t i v e Agreement C R - 8 1 0 6 9 1 - 0 1 - 0 ) . The work c o u l d n o t have been completed w i t h o u t the e x c e l l e n t t e c h n i c a l sup p o r t p r o v i d e d b y S h a r o n Wong a n d W i l l i a m G i b b .

Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9.

Batchelor, G . S . ; Walker, K . C . Arch. Ind. Hyg. 1954, 10, 522-529. Franklin, C . A . ; Fenske, R . A . ; Greenhalgh, R.; Mathieu, L . ; Denley, B . V . ; Leffingwell, J . T . ; Spear, R.C. J. Toxicol. Environ. Health 1981, 7, 715-31. Fenske, R.A. Ph.D. Thesis university of C a l i f o r n i a , Berkeley, 1984. Durham, W.F.; Wolfe, H.R. Bull. World Health Organization 1962, 26, 75-91. Gloxhuber, C.; Bloching, H. Toxicology Annual 1979, 3, 171-203. Davies, J . E . ; Freed, V . H . ; Enos, H . F . ; Duncan, R.C.; Barquet, Α.; Morgade, C.; Peters, L.J.; Danauskas, J . X . J. Occup. Med. 1982, 24, 464-68. Wolfe, H.R.; Durham, W.F.; Armstrong, J . F . Arch. Environ. Health 1967, 14, 622-33. Wolfe, H . R . ; Armstrong, J . F . ; S t a i f f , D.C.; Comer, S.W. Arch. Environ. Health 1972, 25, 29-31. Davis, J . E . Residue Reviews 1980, 75, 33-50.

RECEIVED September 24,

1984


Dermal Exposure Related to Pesticide Use - American Chemical Society

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