Dermal Exposure Related to Pesticide Use Downloaded from pubs.acs.org by UNIV OF MICHIGAN ANN ARBOR on 11/20/18. For personal use only.
11 Monitoring Field Applicator Exposure to Pesticides T. L. LAVY and J. D . M A T T I C E Altheimer Laboratory, Department of Agronomy, University of Arkansas, Fayetteville, AR 72701
For the past 6 years the research team at the pesticide laboratory of the University of Arkansas has been conducting research on pesticide applicator exposure studies. During this period we have analyzed over 9000 samples from nine different studies to evaluate applicator exposure to 2,4,5-T, 2,4-D, 2,4-DP, paraquat, EPN, MSMA, picloram, and methyl parathion. During these studies we have attempted to determine, not only how much exposure applicators receive, but also how large a dose they absorb. We have attempted to learn how to best collect samples incorporating quality controls which allow us to best evaluate exposure and dose measurements. The results of our individual studies have been published elsewhere (see related literature following the references). Consequently, the primary purpose here is to present further details and some general conclusions of these studies. In addition, we offer our opinions on how best to design and conduct exposure studies. Exposure and Dose The following three parameters are involved in determining the potential health effects of pesticides on humans: 1) t o x i c i t y
of the compound, 2) absorbed d o s e , and 3) a b s o r p t i o n and e x c r e t i o n rates. I t i s i m p o r t a n t to note the d i f f e r e n c e between exposure and dose. Exposure to a c h e m i c a l o c c u r s when a person makes c o n t a c t with a chemical. Unless the compound causes damage t o the p a r t of the body i t comes i n t o c o n t a c t w i t h , exposure per se does not r e p r e s e n t a danger. The absorbed dose may be d e f i n e d as t h a t amount o f the c h e m i c a l t h a t a c t u a l l y g e t s i n s i d e the body. The amount t h a t e n t e r s the body i s r e l a t e d t o the amount o f exposure o c c u r r i n g but many f a c t o r s p l a y a r o l e i n d e t e r m i n i n g the f r a c t i o n o f the exposure t h a t i s absorbed i n t o the body. Some o f these f a c t o r s p r o b a b l y c o n t r o l l i n g the a b s o r p t i o n i n c l u d e the b i n d i n g p r o p e r t i e s of the c h e m i c a l , v o l a t i l i t y o f the c h e m i c a l , r e s i s t a n c e to p h o t o d e c o m p o s i t i o n , the m o i s t u r e and l y p o p h i l l i c
0097-6156/85/ 0273-0163S06.00/0 © 1985 A m e r i c a n C h e m i c a l Society
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p r o p e r t i e s o f t h e s k i n c o n t a c t e d , p o r t i o n o f t h e body c o n t a c t e d , and d u r a t i o n o f the s k i n - c h e m i c a l c o n t a c t . The r e t e n t i o n time in the body depends upon t h e r a t e o f a b s o r p t i o n and t h e r a t e a t which t h e chemical i s e x c r e t e d from the body. Quantitative measures o f danger t o t h e human a r e a l s o dependent upon the t o x i c i t y of the c h e m i c a l . Exposure i n i t s e l f i s i m p o r t a n t from a h e a l t h s t a n d p o i n t t o the e x t e n t i t governs the absorbed d o s e . Collection
o f Samples
D u r i n g most o f these s t u d i e s we have a n a l y z e d samples from t h r e e d i f f e r e n t s o u r c e s 1) a i r m o n i t o r s f o r d e t e r m i n i n g the c o n c e n t r a t i o n o f p e s t i c i d e i n t h e a i r , 2) p a t c h e s a t t a c h e d t o t h e a p p l i c a t o r s c l o t h i n g t o o b t a i n an e s t i m a t e o f dermal e x p o s u r e , and 3) u r i n e t o d e t e r m i n e t h e absorbed d o s e . The c o n c e n t r a t i o n o f p e s t i c i d e i n t h e a i r in the w o r k e r ' s b r e a t h i n g zone was d e t e r m i n e d by a t t a c h i n g t o t h e w o r k e r ' s b e l t a b a t t e r y - p o w e r e d pump w i t h a known f l o w r a t e . An i n l e t tube c o n t a i n i n g t h e a p p r o p r i a t e t r a p p i n g medium was a t t a c h e d t o t h e pump w i t h a l e n g t h o f Tygon tubing. The i n l e t tube was then a t t a c h e d to the w o r k e r ' s c o l l a r . The t o t a l time t h a t the pump was on was recorded. S i n c e the f l o w r a t e through the pump was known, t h e volume o f a i r drawn through the pump c o u l d be c a l c u l a t e d . The amount o f p e s t i c i d e on t h e t r a p p i n g medium d i v i d e d by t h e volume of a i r p u l l e d through t h e r e s i n g i v e s t h e c o n c e n t r a t i o n o f p e s t i cide i n the a i r . A n a l y s i s o f gauze or denim patches of known a r e a a t t a c h e d t o c l o t h i n g near bare s k i n areas a l l o w e d us t o e s t i m a t e the exposure per u n i t area f o r t h a t s k i n . E s t i m a t e s o f t h e a r e a of bare s k i n based on photographs o f t h e workers and i n f o r m a t i o n from Durham and Wolfe (1962) enabled us t o e s t i m a t e the amount of p e s t i c i d e d e p o s i t e d on the s k i n . In the case o f p i c l o r a m and t h e phenoxy compounds, a n a l y s i s of samples from t o t a l u r i n e e x c r e t e d each 24 h enabled us t o d e t e r m i n e the amount of absorbed d o s e . I t has been shown (Matsumura, 1970; G e h r i n g , 1973; and S a u e r h o f f , 1977) t h a t both 2,4-D and 2 , 4 , 5 - T a r e e x c r e t e d i n the u r i n e almost q u a n t i t a t i v e l y w i t h i n 5 days o f b e i n g o r a l l y i n g e s t e d ; t h e r e f o r e , measuring the t o t a l amount of these compounds e x c r e t e d i n the u r i n e over t h i s time g i v e s a good measurement o f absorbed d o s e . I t i s r e a l i z e d t h a t the p h a r m a c o k i n e t i c s g o v e r n i n g a b s o r p t i o n and e x c r e t i o n r a t e s f o r many p e s t i c i d e s have not been f u l l y e v a l uated. T h i s f a c t should not a u t o m a t i c a l l y r e l e a s e the r e s e a r c h e r c o n d u c t i n g a p p l i c a t o r exposure measurements from any o b l i g a t i o n s to attempt t o g a t h e r i n f o r m a t i o n r e g a r d i n g the absorbed d o s e . S i n c e a n a l y s i s o f u r i n e sometimes r e v e a l s t h e presence o f a d e g r a d a t i o n p r o d u c t or t h e p a r e n t p e s t i c i d e i t s e l f , as i n t h e case o f t h e phenoxy h e r b i c i d e s , a r e s e a r c h e r i s r e m i s s i f he does not at l e a s t attempt t o l o c a t e a d e f i n a b l e u r i n a r y component. A i r was shown t o be a very minor r o u t e f o r i n t e r n a l dose. Even i f a l l t h e p e s t i c i d e t h a t a person b r e a t h e d i n were a b s o r b e d , i t would s t i l l account f o r o n l y a f r a c t i o n of 1% o f the absorbed dose as measured by u r i n e a n a l y s i s . We had hoped t h a t t h e r e would be a good c o r r e l a t i o n between
11.
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the exposure as d e t e r m i n e d by a n a l y z i n g p a t c h e s and t h e t o t a l absorbed dose as determined by a n a l y s i s o f u r i n e . I f the c o r r e l a t i o n d i d e x i s t , f u t u r e exposure s t u d i e s would be much e a s i e r t o perform. They c o u l d be a c c o m p l i s h e d i n one d a y , and t h e r e would be no need f o r c o l l e c t i o n , s t o r a g e , and t r a n s p o r t a t i o n o f u r i n e samples over a s e v e r a l day p e r i o d . However, i n s t u d i e s i n v o l v i n g 40 workers a p p l y i n g phenoxy h e r b i c i d e s we found a very poor c o r r e l a t i o n between t h e amount d e p o s i t e d on patches and t h e amount e x c r e t e d i n u r i n e . S i n c e a i r was an e x t r e m e l y minor pathway t o absorbed dose and s i n c e t h e r e was a very poor c o r r e l a t i o n between t h e amount o f p e s t i c i d e on t h e patches and t h e amount o f p e s t i c i d e i n t h e u r i n e , we have chosen i n our l a s t phenoxy study t o a n a l y z e o n l y u r i n e samples s i n c e they p r o v i d e a measurement o f t h e absorbed dose whether i t s e n t r y i n t o t h e body i s v i a o r a l i n g e s t i o n , i n h a l a t i o n , o r dermal a b s o r p t i o n . Overcoming
Inconsistencies
and M i n i m i z i n g
Errors
We have found t h a t t h e r e i s c o n s i s t e n t l y a wide v a r i a t i o n i n expos u r e from worker t o worker p e r f o r m i n g t h e same duty and a l s o f o r the same worker p e r f o r m i n g t h e same j o b a t two d i f f e r e n t t i m e s . To h e l p overcome t h e problem o f l a r g e , i n h e r e n t v a r i a b i l i t y , l a r g e crew s i z e s a r e s u g g e s t e d . In our l a t e s t 2,4-D f o r e s t r y ground a p p l i c a t o r study t h e s i m u l t a n e o u s m o n i t o r i n g o f 20 workers u s i n g t h e same a p p l i c a t i o n method has been employed. In a l l o f our s t u d i e s where u r i n e has been a n a l y z e d , we have c o l l e c t e d one t o t a l 2 4 - h sample o r two 12-h samples over t h e 5-day p e r i o d . To d e t e r m i n e t h e amount o f t h e p e s t i c i d e a b s o r b e d , one needs t o know both t h e volume o f u r i n e e x c r e t e d and t h e c o n c e n t r a t i o n of p e s t i c i d e in that u r i n e . We have observed more than a 1 0 - f o l d d i f f e r e n c e i n t h e volume o f u r i n e e x c r e t e d by two d i f f e r e n t people d o i n g t h e same type o f work. Consequently, t r y i n g t o d e t e r m i n e dose based upon t h e c o n c e n t r a t i o n o f a grab sample and a " t y p i c a l " o r " a v e r a g e " e x c r e t i o n volume i s unacceptable. Without t h e t o t a l u r i n e sample, two people who have r e c e i v e d t h e same absorbed dose c o u l d show a 1 0 - f o l d d i f f e r e n c e i n c o n c e n t r a t i o n o f p e s t i c i d e i n t h e i r u r i n e and, c o n s e q u e n t l y , i n t h e i r absorbed dose s i m p l y because o f d i l u t i o n . Conducting the F i e l d A p p l i c a t o r
Exposure
Studies
The f o l l o w i n g d e s c r i b e s i m p o r t a n t c o n s i d e r a t i o n s t h a t we have found t o be e s s e n t i a l t o a w e l l - d e s i g n e d f i e l d a p p l i c a t o r exposure t o p e s t i c i d e study. F i r s t , a d e t a i l e d p r o t o c o l c r i t i q u e d by s e v e r a l knowledgeable r e s e a r c h e r s i s e s s e n t i a l . I t i s nearly i m p o s s i b l e t o d e v i s e a p r o t o c o l which has t o o much d e t a i l . One must attempt t o p l a n f o r a l l o f t h e p o s s i b l e p i t f a l l s which may occur. Laboratory Techniques. P r i o r t o i n i t i a t i n g a f i e l d study, a l l l a b o r a t o r y components must be r e a d y . 1. One must d e t e r m i n e t h a t t h e t e c h n i c i a n s and equipment can s u c c e s s f u l l y e x e c u t e the c o n f i r m e d method t h a t w i l l be used t o a n a l y z e t h e a c t u a l f i e l d samples.
166 2.
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6.
DERMAL EXPOSURE RELATED TO PESTICIDE USE I t must be demonstrated t h a t a high and r e p e a t a b l e r e c o v e r y p e r c e n t a g e i s a t t a i n a b l e from a l l samples at s e v e r a l p e s t i cide concentration l e v e l s . One should know the s t o r a g e and s t a b i l i t y c h a r a c t e r i s t i c s o f each sample type o r have made p r o v i s i o n s t o guard a g a i n s t degradation p r i o r to a n a l y s i s . F o r t i f i c a t i o n o f s e v e r a l samples, a minimum o f 10% of t h e t o t a l unknowns should be made and these samples i n t e r s p e r s e d among the a c t u a l "unknown" samples. These samples should be l a b e l l e d i n such a way t h a t the a n a l y s t w i l l not know they are f o r t i f i e d samples. A second c o n f i r m a t o r y column o r a d i f f e r e n t a n a l y t i c a l t e c h nique should be employed t o c o n f i r m t h e i d e n t i t y o f the a n a lyte. I f u r i n e o r blood samples a r e to be used t o d e t e r m i n e t h e absorbed d o s e , i t i s h e l p f u l t o have p r e - s t u d y i n f o r m a t i o n which w i l l g i v e the r e s e a r c h e r an o p p o r t u n i t y t o d e s i g n h i s sample c o l l e c t i o n scheme i n a manner which w i l l be s i m p l e s t t o a c h i e v e and which w i l l p r o v i d e t h e most q u a n t i t a t i v e information. Much has been w r i t t e n w i t h r e g a r d t o the e x c r e t i o n r a t e s , q u a n t i t a t i v e n a t u r e o f the e x c r e t i o n , and o t h e r d a t a on the phenoxy h e r b i c i d e s . F o r o t h e r compounds where l e s s i s known, i f t h e m a n u f a c t u r e r can not p r o v i d e d e t a i l e d i n f o r m a t i o n on the e x c r e t i o n d a t a , t h e r e s e a r c h e r may be r e q u i r e d t o conduct a small c o n t r o l l e d s t u d y , e v a l u a t i n g e x c r e t i o n r a t e , and o t h e r i m p o r t a n t c h a r a c t e r i s t i c s o f the compound p r i o r t o c o n d u c t i n g ev f u l l - s c a l e f i e l d s t u d y . It is n e c e s s a r y t o know i f one should a n a l y z e f o r the parent compound or a m e t a b o l i t e . I f a m e t a b o l i t e i s t o be a n a l y z e d , i t i s n e c e s s a r y t o know i f i t s amount can be r e l a t e d t o the dose o f the p a r e n t compound.
Crew P a r a m e t e r s . Much o f t h e a c c u r a c y and completeness o f sample c o l l e c t i o n depends upon the human s u b j e c t s who a r e b e i n g m o n i tored. I f one i s i n t e r e s t e d i n measuring the dose o f crewmembers c a r r y i n g out t h e i r normal a c t i v i t i e s , i t i s i m p o r t a n t t o comm u n i c a t e w i t h them and t r y t o m o n i t o r t h e i r a c t i v i t i e s w i t h o u t i n t e r r u p t i n g t h e i r normal r o u t i n e s . 1. S e l e c t i o n o f crewmembers accustomed t o p e r f o r m i n g the o p e r a t i o n b e i n g m o n i t o r e d i s mandatory i f t h e r e s e a r c h e r ' s goal i s t o measure " r e a l - w o r l d " exposure l e v e l s . 2.
Crew m o t i v a t i o n i s a v i t a l component o f any a p p l i c a t o r exposure study. Without t h e i n t e r e s t , c o n c e r n , and c o o p e r a t i o n o f the f i e l d crew, t h e r e i s l i t t l e l i k e l i h o o d o f c o n d u c t i n g a meaningful exposure s t u d y . I t i s i m p o r t a n t f o r the p r i n c i p a l i n v e s t i g a t o r t o go t o the f i e l d , meet t h e w o r k e r s , and d i s c u s s t h e p r o t o c o l w i t h them at l e a s t once p r i o r t o a c t u a l l y beginning the study. The crew must be aware o f , and involved i n , the a c t i o n . One method we have used t o h e l p m o t i v a t e crewmembers i s t o o f f e r them $100 per week f o r t h e i r f u l l c o o p e r a t i o n i n the study which r e q u i r e s them ( t o the b e s t o f t h e i r a b i l i t y ) t o d e l i v e r e v e r y drop o f t h e i r u r i n e b e g i n n i n g a day b e f o r e the a p p l i c a t i o n through at l e a s t f o u r days f o l l o w i n g a p p l i c a t i o n . T h i s r e q u e s t may be annoying but it is essential. I t may r e q u i r e t h e worker t o c a r r y h i s
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u r i n e c o n t a i n e r t o such p l a c e s as c h u r c h , on d a t e s , on t r i p s , e t c . In emergencies where some u r i n e was l o s t and i t was p o s s i b l e f o r t h e worker t o e s t i m a t e t h e amount l o s t , he would r e c o r d t h i s i n f o r m a t i o n . When an e x c e s s i v e number o f " e m e r g e n c i e s " o c c u r r e d , t h e $100 was t o be w i t h h e l d . As an enforcement t o o l each worker was aware t h a t each o f h i s u r i n e samples was b e i n g a n a l y z e d f o r c r e a t i n i n e c o n t e n t . We had i n d i c a t e d t o t h e worker t h a t w i t h t h i s measurement we c o u l d t e l l whether he p r o v i d e d us w i t h a l l o f h i s u r i n e or o n l y a p o r t i o n of i t . A l t h o u g h a n a l y s i s o f u r i n e samples f o r c r e a t i n i n e does not always p r o v i d e as q u a n t i t a t i v e t o o l as d e s i r e d f o r documenting t h e completeness o f t h e u r i n e sample, i t s use was e f f e c t i v e i n g a i n i n g c o m p l i a n c e o f the workers. 3.
4.
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I t i s n e c e s s a r y t o be knowledgeable about the a p p l i c a t o r h i s t o r y o f t h e crewmembers i n v o l v e d . I f they have been a p p l y i n g t h e p e s t i c i d e o f concern i n weeks p r i o r t o c o n d u c t i n g t h e t e s t , t h e workers may e n t e r t h e t e s t w i t h a p o s i t i v e background l e v e l . F o r t h a t reason i t i s always e s s e n t i a l t o take p r e - a p p l i c a t i o n day u r i n e o r b l o o d samples t o e s t a b l i s h t h e q u a n t i t y o f absorbed dose more c l e a r l y . Crewmembers must be f u l l y informed and knowledgeable c o n c e r n i n g how t o take t h e sample, when t o begin c o l l e c t i o n , how t o s t o r e t h e sample, t h e numbering scheme employed and how t o d e l i v e r t h e sample t o t h e c e n t e r f o r s t o r i n g and p r o cessing. P r i o r t o p a r t i c i p a t i n g i n the s t u d y , t h e workers should s i g n c o n s e n t f o r m s , which in w r i t i n g e x p l a i n s t o them t h e i n t e n t of t h e s t u d y , how i t i s t o be c a r r i e d o u t , and t h e f a c t t h a t they may q u i t at any t i m e . In no case s h o u l d t h e study r e q u i r e the worker t o become more h e a v i l y exposed t o p e s t i c i d e than he o r d i n a r i l y does.
Q n - S i t e Requirements.
In c o l l e c t i n g
s t r a t e g y must p r o v i d e f o r s u p p l i e s
t h e samples,
a well-planned
and equipment as w e l l as
s t o r a g e , h a n d l i n g , and s h i p p i n g o f t h e samples. 1. The c o l l e c t i o n s i t e s h o u l d have adequate c o o l e r space f o r s t o r i n g samples. In a d d i t i o n , bench space i s n e c e s s a r y f o r w e i g h i n g u r i n e samples, t a k i n g a l i q u o t s f o r shipment t o t h e analytical laboratory, e t c . 2. I t i s i m p o r t a n t t h a t one o f t h e f i e l d members be i n c h a r g e o f r e c o r d i n g s t a r t i n g and s t o p p i n g times and f o r c a l l i n g o f f t h e o p e r a t i o n i f i n v i o l a t i o n o f wind o r temperature c o n d i t i o n s . 3. S t r i c t adherence should be made t o t h e p r o t o c o l . When i r r e g u l a r i t i e s o c c u r , t h e study should c o n t i n u e b u t e x t e n s i v e notes should be made. Our s t u d i e s have i n d i c a t e d t h a t c o n s i d e r a b l y more exposure o c c u r s t o workers when i r r e g u l a r i t i e s such as m a l f u n c t i o n i n g equipment o c c u r . 4. A photo o f each f i e l d worker i n h i s a p p l i c a t i o n a t t i r e i s a must. These photos a r e e s p e c i a l l y h e l p f u l i n e s t i m a t i n g t h e amount of bare s k i n exposed, type o f s h i r t , g l o v e s , b o o t s , and o t h e r c l o t h i n g worn. 5. F o r t i f i c a t i o n o f samples i n t h e f i e l d i s as i m p o r t a n t , or perhaps more s o , than those i n t h e l a b o r a t o r y . Field f o r -
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6.
7.
DERMAL EXPOSURE RELATED TO PESTICIDE USE t i f i c a t i o n o f u r i n e samples w i t h known amounts o f the p e s t i c i d e in q u e s t i o n p r o v i d e s the r e s e a r c h e r w i t h an i n s u r a n c e policy. I f the samples g e t t e m p o r a r i l y l o s t i n t r a n s i t , get warmer than t h e p r o t o c o l a l l o w s , o r i f e x c e s s i v e time e l a p s e s b e f o r e a n a l y s i s , meaningful d a t a can s t i l l be o b t a i n e d s i n c e presumably t h e f o r t i f i e d samples w i l l have undergone the same h i s t o r y as the a c t u a l f i e l d unknowns. The u r i n e used f o r f o r t i f i c a t i o n s h o u l d be from a sample t h a t was c o l l e c t e d t h e day p r i o r t o s p r a y i n g t o i n s u r e low chemical background. L a b e l l i n g o f t h e f i e l d f o r t i f i e d samples s h o u l d be done i n a manner t h a t the chemist i n the l a b o r a t o r y can not d i f f e r e n t i a t e between t h e unknown and t h e f o r t i f i e d sample at the time o f a n a l y s i s . Use o f p r e - p r i n t e d s t i c k - o n l a b e l s prepared i n t h e l a b o r a t o r y but a t t a c h e d t o the c o n t a i n e r s i n the f i e l d g r e a t l y f a c i l i t a t e r e c o r d k e e p i n g and sample c o l l e c t i o n . Even then sometimes problems o c c u r . E x t e n s i v e notes should be taken i n the f o l l o w i n g a r e a s : wind and c l i m a t i c c o n d i t i o n s , d u r a t i o n o f s t u d y , k i n d and amounts of m a t e r i a l used, type o f equipment used, a l l a p p l i c a t i o n parameters ( n o z z l e s i z e and t y p e , h e i g h t above canopy i f a e r i a l ) and, as mentioned e a r l i e r , a l l i r r e g u l a r i t i e s w i t h regard t o the a p p l i c a t i o n .
Follow-up R e s p o n s i b i l i t i e s . S i n c e the f i e l d crews p l a y such a v i t a l r o l e in a s u c c e s s f u l f i e l d a p p l i c a t o r exposure s t u d y , i t i s i m p o r t a n t t h a t the r e s e a r c h e r f i n d t h e time t o s h a r e h i s r e s u l t s w i t h the f i e l d crew. Rapid sample a n a l y s i s w i l l r e s u l t i n more a c c u r a t e a n a l y s e s and a i d i n r a p i d p u b l i c a t i o n o f the r e s u l t s . I t i s i m p o r t a n t t h a t the f a c t s d e r i v e d from study be r e l a y e d t o the s c i e n t i f i c community through j o u r n a l p u b l i c a t i o n . The d a t a should be r e p o r t e d i n a c l e a r and uniform manner t o a l l o w comparison with other published s t u d i e s . In a d d i t i o n , t h e r e s u l t s should be p r e s e n t e d t o the worker i n t h e f i e l d i n a manner he can understand. Newspapers, t e l e v i s i o n , or farm magazines can be e f f e c t i v e l y used. O b s e r v a t i o n s on R e s u l t s From Our S t u d i e s . ( F o r more complete d a t a , c o n s u l t the R e l a t e d L i t e r a t u r e . ) In both a 2 , 4 , 5 - T and a 2,4-D a p p l i c a t o r exposure study some o f t h e workers e n t e r e d t h e study with low but p o s i t i v e l e v e l s of the phenoxy compound i n their urine. I t has been shown t h a t contaminated g l o v e s and footwear can s e r v e as a c o n t i n u i n g exposure s o u r c e . In s u r v e y s conducted w i t h many f o r e s t r y a p p l i c a t o r s i t has been r e v e a l e d t h a t they r o u t i n e l y shower and change c l o t h e s d a i l y a f t e r worki n g w i t h h e r b i c i d e s i n t h e f o r e s t ; however, when asked whether they used t h e same boots and g l o v e s , almost i n v a r i a b l y t h e r e p l y was t h a t they d i d wear the same boots and sometimes even the same g l o v e s even when not u s i n g c h e m i c a l s . Other r e s e a r c h e r s have found t h a t lower body p a r t s may be exposed t o high p e s t i c i d e levels. As an example s t u d i e s by Nigg and Stamper (1983) have shown t h a t the l e g s and f e e t are the most h e a v i l y exposed body parts. Thus, i t would not be s u p r i s i n g t h a t boots were h e a v i l y contaminated.
11.
LAVY AND MATTICE
Monitoring
Field Applicator
Exposure
F o r many crewmembers, i n a d d i t i o n t o t h e exposure o c c u r r i n g d u r i n g normal a p p l i c a t i o n d u t i e s s i g n i f i c a n t exposure and c o n sequent absorbed dose o c c u r s d u r i n g equipment r e p a i r and cleaning. E v i d e n c e f o r t h i s type o f r e - e x p o s u r e becomes e v i d e n t when one compares t h e u r i n e e x c r e t i o n p a t t e r n from a normal o n e time exposure ( F i g u r e 1) w i t h t h a t of a crewmember, who presuma b l y r e c e i v e d c o n t i n u e d r e - e x p o s u r e f o r s e v e r a l days f o l l o w i n g h e r b i c i d e a p p l i c a t i o n (Lavy and M a t t i c e , 1984) ( F i g u r e 2 ) . S i n c e a n a l y s i s o f our t o t a l u r i n e e x c r e t i o n p a t t e r n s r e v e a l s t h a t workers r o u t i n e l y r e c e i v e i n a d v e r t e n t exposure at times i n a d d i t i o n t o the a p p l i c a t i o n d a y , i t i s imperative that t o t a l u r i n e be c o l l e c t e d i f one i s i n t e r e s t e d i n o b t a i n i n g q u a n t i t a t i v e measurements o f t h e t o t a l absorbed d o s e . Our r e s u l t s i n t h e 2 , 4 , 5 - T study have shown t h a t m i x e r s o f p e s t i c i d e c o n c e n t r a t e s and backpack s p r a y e r s who r o u t i n e l y walk through t h e t r e a t e d a r e a r e c e i v e the h i g h e s t absorbed d o s e . Flagmen f o r t h e h e l i c o p t e r crews and crew s u p e r v i s o r s absorbed lower amounts than t h e mixers and backpack s p r a y e r s . Aerial a p p l i c a t i o n crews appeared t o have lower absorbed doses than backpack o r m i s t blower crews. The absorbed dose f o r t h e crewmembers ranged from 0.001 mg/kg f o r t h e h e l i c o p t e r flagmen t o 0.062 mg/kg f o r t h e mixers o f t h e c o n c e n t r a t e s (Lavy e t a l . , 1980). R e s u l t s from our study on h e l i c o p t e r - a p p l i e d 2 , 4 - D conducted i n t h e P a c i f i c Northwest showed t h a t p i l o t s and batchmen r e c e i v e d the h i g h e s t absorbed dose f o l l o w e d by m e c h a n i c s , s u p e r v i s o r s , and observers. The o b s e r v e r s were s t a t i o n e d 200 t o 500 f e e t from t h e heliport. A p p l i c a t o r s o f p e s t i c i d e s do r e c e i v e an absorbed d o s e . The i m p o r t a n t q u e s t i o n i s whether o r not t h i s absorbed dose i s dangerous. We have c a l c u l a t e d margin o f s a f e t y (M0S) v a l u e s f o r our s t u d i e s i n o r d e r t o answer t h e q u e s t i o n . We have used w o r s t case d a t a ( i . e . worker w i t h t h e h i g h e s t absorbed d o s e ) ; t h u s , M0S v a l u e s f o r t h e t y p i c a l worker w i l l p r o b a b l y be g r e a t e r . A v a l u e o f 20 mg/kg 2 , 4 , 5 - T has been a s c r i b e d by EPA, i n t h e i r P o s i t i o n Document 1 on 2 , 4 , 5 - T as used i n t h e RPAR p r o c e s s , as t h e No Observed E f f e c t L e v e l (NOEL). The s c i e n t i f i c a d v i s o r y panel on 2,4-D s e t a v a l u e o f 24 mg/kg as NOEL ( H a l l , 1 9 8 0 ) . L e v e l s f o r both o f these compounds a r e f o r t e r a t o g e n i c i t y , t h e most s e n s i t i v e o f t h e h e a l t h e f f e c t t e s t s i n u s e . By d i v i d i n g the absorbed dose d a t a ( o b t a i n e d by a n a l y z i n g t h e t o t a l u r i n e e x c r e t e d on t h e day o f t h e a p p l i c a t i o n p l u s t h e next f o u r days) i n t o t h e a p p r o p r i a t e NOEL, t h e MOS v a l u e i s o b t a i n e d . These v a l u e s f o r t h e workers w e a r i n g normal c l o t h i n g i n t h e 2,4-D study a r e as f o l l o w s : p i l o t s and batchmen 1200; mechanics 4400; s u p e r v i s o r s 1 0 , 0 0 0 ; and o b s e r v e r s 4 9 , 0 0 0 . Thus, none o f t h e workers appear t o be r e c e i v i n g an absorbed dose even a p p r o a c h i n g a h e a l t h threatening l e v e l . The o b s e r v e r s i n t h e 2,4-D study were p u r p o s e l y added t o t h e study t o a l l o w a measurement o f t h e absorbed dose o c c u r r i n g t o those nearby but not i n v o l v e d w i t h t h e s p r a y operation. Normal c l o t h i n g a f f o r d e d a high l e v e l o f p r o t e c t i o n t o t h e workers as determined by a n a l y z i n g patches a t t a c h e d both o u t s i d e and i n s i d e t h e i r normal c l o t h i n g . However, s i n c e some compounds
170
DERMAL EXPOSURE RELATED TO PESTICIDE USE
0.10
* Treatment * * Treotment
F i g u r e 1.
Urinary 2,4-D.
I - Ordinary
precautions observed
2 - Special precautions observed
excretion
p a t t e r n f o r a one-time exposure t o
LAVY AND MATTICE
Figure
2.
Monitoring
Field Applicator
Exposure
U r i n a r y e x c r e t i o n p a t t e r n f o r a person b e i n g exposed t o 2,4-D a f t e r i n i t i a l e x p o s u r e .
172
DERMAL EXPOSURE RELATED TO PESTICIDE USE
a r e c o n s i d e r a b l y more t o x i c t o humans than are the phenoxy h e r b i c i d e s , when a p p l y i n g these compounds p r o t e c t i v e c l o t h i n g may be necessary. R e s e a r c h e r s have a r e s p o n s i b i l i t y t o choose c o m f o r t a b l e , i n e x p e n s i v e c l o t h i n g or d e v i c e s t o p r o t e c t the worker. If p r a c t i c a l c l o t h i n g i s not p r o v i d e d , more than l i k e l y i t w i l l not be worn by t h e worker u n l e s s c o n s t a n t enforcement i s made. Some p r o t e c t i v e c l o t h i n g , i f worn in t h e South i n t h e summer, w i l l cause s e v e r e heat problems f o r t h e w o r k e r s . The use o f c l o s e d systems i s e f f e c t i v e i n d e c r e a s i n g worker exposure. Use o f c l o s e d systems was common f o r a e r i a l a p p l i c a t o r s u s i n g t h e more t o x i c methyl p a r a t h i o n . I t was i n t e r e s t i n g t h a t hand m i x i n g and a p p l i c a t i o n was more common when compounds w i t h lower t o x i c i t y were b e i n g used. A w e l l - d e s i g n e d a p p l i c a t o r exposure study can p r o v i d e i n f o r mation on t h e e x t e n t of the absorbed dose people a p p l y i n g the p e s t i c i d e are r e c e i v i n g . Our s t u d i e s have shown t h a t people a p p l y i n g p e s t i c i d e s do r e c e i v e an absorbed d o s e , and d i f f e r i n g amounts o f dose a r e a s s o c i a t e d w i t h d i f f e r e n t a p p l i c a t i o n t e c h niques. We have found no c a s e where a worker has r e c e i v e d a dose near a l e v e l t h a t causes e f f e c t s t o be observed i n l a b o r a t o r y animals. I f an e x t r e m e l y t o x i c chemical i s b e i n g u s e d , t h e absorbed dose can be reduced by use o f p r o t e c t i v e c l o t h i n g and a l s o by t h e use of c l o s e d systems. Nontechnical
Summary
Through these s t u d i e s we have a c q u i r e d c o n s i d e r a b l e d a t a on human exposure as w e l l as e x p e r i e n c e i n d e s i g n i n g and c o n d u c t i n g r e s e a r c h t o m o n i t o r r e a l - l i f e exposure o f p e s t i c i d e a p p l i c a t o r s . Exposure i s r e l e v a n t t o human h e a l t h o n l y i n r e l a t i o n t o the dose taken i n t o t h e body, i t s t o x i c i t y , and t h e r a t e o f e x c r e t i o n . In our s t u d i e s we have m o n i t o r e d no group nor i n d i v i d u a l whose dose approaches a l e v e l which c o u l d a f f e c t human h e a l t h . Our s t u d i e s have shown t h a t exposure and dose a r e i n f l u e n c e d m a t e r i a l l y by human a t t i r e and h a b i t s , t y p e and f u n c t i o n of equipment, and s a f e t y p r e c a u t i o n s such as p r o t e c t i v e c l o t h i n g or washing soon a f t e r exposure to a c o n c e n t r a t e . Acknowledgments The a u t h o r s a p p r e c i a t e p r e p a r i n g t h i s paper.
the a s s i s t a n c e
o f Martha D a v i s
in
Literature Cited Durham,W.F.;Wolfe, H.R. Bulletin of World Health Organization, 1962, 26, 75-91. Matsumura, A. Sangyo Igaku 1970, 12, 446-51. Gehring, P.J.; Kramer, C.G.; Schwetz, B.A.; Rose, J.Q.; Rowe, V.K. Toxicol, and Appl. Pharmacol. 1973, 26, 352-61. Sauerhoff,M.W.;Braun,W.H.;Blau, G. E.; Gehring, P.J. Toxicology 1977, 8, 3-11. Nigg, H.N.; Stamper, J.H. Chemosphere, 1983, 12(2), 209-215.
11.
LAVY
AND
MATTICE
Monitoring
Field Applicator Exposure
Lavy, T.L.; Mattice, J.D. Project Completion Report to United States Department of Agriculture on Exposure of Forestry Applicators Using Herbicide Formulations Containing 2,4-D, 2,4-DP (dichlorprop) or Picloram in Non-Aerial Applications, Spring and Summer, 1982. 1984, in press. Lavy, T.L.; Shepard, J.S.; Mattice, J.D. Journal of Agriculture and Food Chemistry, 1980, 28, 626-30. Hall, J.F. letter to the U.S. Environmental Protection Agency dated 14 Nov. 1980, p. 6, in Lavy, T.L., "Determination of 2,4-D Exposure Received by Forestry Applicators," project completion report submitted to the National Forest Products Association, Washington, D.C., 1980. Related Literature Flynn, R.R. Masters Thesis, University of Arkansas, Fayetteville, 1983. Forbess, R.C.; Talbert, R.E.; Lavy, T.L.; Morris, J.P. "Evaluation of Paraquat Use and Applicator Exposure in Grape Vineyards," project completion report to the Southern Region Pesticide Impact Assessment Program, Washington, D.C., 1981. Lavy, T.L. Project Completion Report to Nation Forest Products Association on Determination of 2,4-D Exposure Received by Forestry Applicators, Spring, 1980. Lavy, T.L.; Mattice, J.D.; Flynn, R.R. Special Technical Testing Publication 795, American Society for Testing and Materials, 1983, 60-74. Lavy, T.L.; Mattice, J.D. In "Chemical and Biological Controls in Forestry"; Garner, Willa Y.; Harvey, John, Jr., Eds.; 1983, 319-330. Lavy, T.L.; Walstad, J.D.; Flynn, R.R.; Mattice, J.D. Journal of Agriculture and Food Chemistry, 1982, 30, 375-81. Leng, M.L.; Lavy, T.L.; Ramsey, J.C.; Braun, W.H. "Review of Studies with 2,4,5-T in Humans Including Applicators under Field Conditions," Paper presented at the American Chemical Society Symposium on Worker Exposure, Washington, D.C., 1981. Lincoln, C.; Lavy, T. "EPN Usage as a Cotton Insecticide," project completion report to the Southern Region Pesticide Impact Assessment Program, Washington, D.C., 1981. Roeth, F.W.; Lavy, T.L.; Burnside, O.C. Weed Science, 1969, 17, 202-05. RECEIVED September 25,
1984
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