Biological Monitoring Technology for Measurement of Applicator

Chapter 19

Biological Monitoring Technology for Measurement of Applicator Exposure

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S. Dubelman and J. E. Cowell Monsanto Agricultural Company, Monsanto Company, St. Louis, MO 63198

The measurement of a pesticide and its metabolites in urine is a direct and accurate means of determining actual applicator exposure. Biological monitoring studies with alachlor are used here to exemplify the techniques necessary for conducting a study and deter mining body dose. Animal metabolism and pharmacokinetic studies provided data about the nature of the metabo l i t e s , the elimination pathway (urine/feces) and the kinetics of excretion. Urine from applicators using alachlor was collected for a 5 day period following application. Twelve-hour urine composites were analyzed by GCMS or HPLC for DEA and HEEA, the chemophores derived from alachlor and its metabolites. Method sensitivity was 5.0 ppb (μg/L) for the total measured residue. Appropriate correction factors derived from animal studies were applied to the measured urinary excretion to determine the body dose. Background A number o f t e c h n i q u e s a r e c u r r e n t l y used t o m o n i t o r a p p l i c a t o r exposure t o p e s t i c i d e s . These i n c l u d e p a s s i v e d o s i m e t r y , b i o l o g i c a l m o n i t o r i n g and f l u o r e s c e n c e v i d e o imaging. T a b l e I shows a comparison o f the d i s t i n c t i v e f e a t u r e s o f each t e c h n i q u e . The main advantage o f p a s s i v e d o s i m e t r y i s t h e ease w i t h which samples can be o b t a i n e d and a n a l y z e d . Analysis i s usually f o r the p a r e n t p e s t i c i d e o n l y , and no metabolism i n f o r m a t i o n i s necessary. T h i s method produces data t h a t i s s u i t a b l e f o r i n c l u s i o n i n g e n e r i c databases c o n t a i n i n g l a r g e numbers o f s t u d i e s w i t h d i f f e r e n t p e s t i c i d e s . T h i s t e c h n i q u e can be used t o measure expo0097-6156/89/0382-0240$06.00/0 © 1989 American Chemical Society

Wang et al.; Biological Monitoring for Pesticide Exposure ACS Symposium Series; American Chemical Society: Washington, DC, 1988.

19.

DUBELMAN AND COWELL

Table I. Technique

Biological Monitoring Technology

241

Comparison o f Exposure Measurement Techniques Measurement

Advantage/Best

Use

Passive Dosimetry

Dermal D e p o s i t i o n (Patches) Inhalation (Air Sampling) Parent P e s t i c i d e Analysis

D i s c r e t e Work Activities Most V u l n e r a b l e Body Areas Simple A n a l y s i s S e p a r a t e Dermal Inhalation Values

Fluorescence/ Imaging

Dermal D e p o s i t i o n (Video Imaging) F l u o r e s c e n t Dye Quantitation

Most V u l n e r a b l e Body Areas E s t i m a t i o n o f Dermal Deposition Education/Training

Biological Monitoring

Excreted P o r t i o n of Body Dose ( U r i n e )

I n t e g r a t e d Exposure: I n h a l a t i o n + Dermal + Ingestion No Need f o r Dermal Absorption Factor No C l o t h i n g P e n e t r a t i o n Assumption C l o s e s t Estimate of T o t a l Body Dose

Pesticide + Metabolite Analysis

sures r e c e i v e d d u r i n g d i s c r e t e work a c t i v i t i e s w i t h i n a workday, which makes i t v a l u a b l e i n e v a l u a t i n g exposure r e d u c t i o n p r a c tices. There are s e v e r a l d i s a d v a n t a g e s i n u s i n g p a s s i v e d o s i m e t r y f o r c a l c u l a t i o n o f body dose. One i s the need t o measure the amount of c h e m i c a l absorbed t h r o u g h the s k i n and l u n g s , o r t o assume 100% a b s o r p t i o n o f the compound. The l a t t e r assumption i s not supported by a number o f r e c e n t s t u d i e s . A l a r g e source o f e r r o r i s a l s o i n h e r e n t i n the e x t r a p o l a t i o n of r e s i d u e s found i n r e l a t i v e l y s m a l l t r a p p i n g d e v i c e s ( e . g . , gauze p a t c h e s ) t o e n t i r e body s u r f a c e a r e a s . S i n c e the p a t c h e s g e n e r a l l y cover 6% o r l e s s o f the body, exposure c o u l d be g r o s s l y over- o r u n d e r - e s t i m a t e d i f p e s t i c i d e d r o p l e t s h i t o r miss the p a t c h . An a d d i t i o n a l assumption l e a d i n g t o over- o r u n d e r - e s t i m a t i o n i n v o l v e s the amount o f p e s t i c i d e i n t e r c e p t e d by c l o t h i n g d u r i n g p e s t i c i d e a p p l i c a t i o n . Scenari o s u s i n g no p r o t e c t i o n (nude a p p l i c a t o r ) , 50%, 80%, o r 100% c l o t h i n g p r o t e c t i o n have been used by EPA i n c a l c u l a t i n g body doses from gauze p a t c h data f o r a number o f p e s t i c i d e s . E s t i m a t e s o f body dose can range s e v e r a l o r d e r s o f magnitude depending on how much body s u r f a c e i s assumed t o be p r o t e c t e d by c l o t h i n g . V i d e o imaging w i t h f l u o r e s c e n t t r a c e r s i s not y e t w i d e l y used. An o b s t a c l e t o w i d e s p r e a d use i s the c u r r e n t u n a v a i l a b i l i t y o f n o n t o x i c f l u o r e s c e n t t r a c e r s w h i c h would be c o m p a t i b l e w i t h a wide


BIOLOGICAL MONITORING FOR PESTICIDE EXPOSURE

242

range o f a g r i c u l t u r a l f o r m u l a t i o n s . The t e c h n i q u e q u a n t i f i e s dermal d e p o s i t i o n , which i s o f t e n t h e major component o f t h e exposure, b u t does n o t account f o r t h e p o r t i o n o f t h e dose r e s u l t i n g from i n h a l a t i o n o r i n g e s t i o n . E s t i m a t e s o f dermal p e n e t r a t i o n are s t i l l n e c e s s a r y f o r c a l c u l a t i o n o f body dose. An i m p o r t a n t advantage o f t h e t e c h n i q u e i s i t s a b i l i t y t o p r o v i d e a v i s u a l q u a l i t a t i v e assessment o f t h e a f f e c t e d body a r e a s . T h i s knowledge can be used t o d e s i g n exposure r e d u c t i o n measures and t o educate a g r i c u l t u r a l workers. The p r i m a r y advantage o f b i o l o g i c a l m o n i t o r i n g i s t h a t t h e a c t u a l body dose can be d i r e c t l y determined by measuring t h e concentration of the p e s t i c i d e or i t s metabolites i n the urine. T h i s dose i n c l u d e s exposure from a l l s o u r c e s : dermal, i n h a l a t i o n and i n g e s t i o n . There i s no need t o determine dermal a b s o r p t i o n o r 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 s , s i n c e a l l these a r e i n t r i n s i c and accounted f o r i n t h e m o n i t o r i n g . The main disadvantage o f t h e t e c h n i q u e i s t h a t d e t a i l e d knowledge o f metabolism and e x c r e t i o n k i n e t i c s i s needed b e f o r e q u a n t i t a t i v e s t u d i e s can be conducted. I n a d d i t i o n , t h i s t e c h n i q u e i s a p p l i c a b l e o n l y t o those chemicals where u r i n e i s t h e major r o u t e o f e x c r e t i o n . N e i t h e r b l o o d n o r f e c e s a r e p r a c t i c a l m a t r i x e s f o r t h e measurement o f t o t a l exposure. Alachlor Studies:

M e t a b o l i s m , E x c r e t i o n and Methods

M e t a b o l i s m and e x c r e t i o n k i n e t i c s s h o u l d be known b e f o r e t h e b i o l o g i c a l m o n i t o r i n g study a r e conducted. R e s u l t s o f these studies f o r a l a c h l o r , 2-chloro-2 ,6 -diethyl-N-(methoxymethyl) a c e t a n i l i d e , t h e a c t i v e i n g r e d i e n t i n Lasso h e r b i c i d e (Monsanto Co.), a r e shown i n T a b l e I I . The r a t metabolism s t u d y ( o r a l d o s i n g ) , r e q u i r e d f o r r e g i s t r a t i o n under FIFRA, p r o v i d e d m e t a b o l i t e i d e n t i f i c a t i o n data w h i c h s e r v e d as a b a s i s f o r d e v e l o p i n g a n a l y t i c a l methods f o r use i n t h e a p p l i c a t o r exposure s t u d y . 1

TABLE I I .

1

R e s u l t s o f M e t a b o l i s m and E x c r e t i o n S t u d i e s on A l a c h l o r

Study Oral Dosing C-Rats

Results I d e n t i f i c a t i o n o f Many M e t a b o l i t e s Y i e l d i n g E i t h e r DEA o r HEEA Upon Hydrolysis

O r a l Dosing C-Mice

I d e n t i f i c a t i o n of Metabolites Containing DEA and HEEA; S p e c i e s Comparison

Intravenous Dosing C-Monkeys

97% Dose Recovered i n U r i n e + Feces 87% Dose E x c r e t e d i n U r i n e 80% Dose E x c r e t e d i n 48 Hours Q u a n t i t a t i o n o f DEA/HEEA R a t i o

Dermal A b s o r p t i o n C-Monkeys

8.5% o f Dose Absorbed Through S k i n 88% o f Dose i n U r i n e

1 4

1 4

14

14


19.

DUBELMAN AND COWELL


243

F o r a l a c h l o r , the mouse metabolism study d i d not p r o v i d e much a d d i t i o n a l knowledge a p p l i c a b l e t o the exposure s t u d y , except f o r c o r r o b o r a t i o n o f m e t a b o l i t e p r o f i l e s and a d d i t i o n a l s p e c i e s compari s o n o f e x c r e t i o n pathways. The i n t r a v e n o u s i n j e c t i o n o f C - l a b e l e d p e s t i c i d e t o monkeys was used t o determine e x c r e t o r y r e c o v e r y and d i s t r i b u t i o n o f the t o t a l amount o f c h e m i c a l between u r i n e and f e c e s . T h i s s t u d y p r o v i d e d c o r r e c t i o n f a c t o r s f o r human e x c r e t o r y r e c o v e r y . Dermal a p p l i c a t i o n o f C - l a b e l e d a l a c h l o r t o monkeys p r o v i d e d e x c r e t i o n data t o determine the l e n g t h o f time f o r u r i n e c o l l e c t i o n by humans. The i n t r a v e n o u s and dermal monkey s t u d i e s showed t h a t 87-88% of the a d m i n i s t e r e d dose was e x c r e t e d i n the monkey u r i n e , and e x c r e t i o n was e s s e n t i a l l y complete f o u r days a f t e r dose a d m i n i s t r a t i o n . T h i s s e r v e d as a b a s i s f o r d e t e r m i n i n g t h a t u r i n e samples would be c o l l e c t e d f o r 5 days i n the a p p l i c a t o r exposure s t u d i e s , and a n a l y t i c a l r e s u l t s would be c o r r e c t e d f o r the 88% e x c r e t o r y f a c t o r i n o r d e r t o a r r i v e a t a t o t a l body dose. T h i s c o r r e c t i o n was i n a d d i t i o n t o a n a l y t i c a l c o r r e c t i o n s n o r m a l l y a p p l i e d f o r l o s s e s i n the r e s i d u e method. A s p e c i e s comparison f o r e x c r e t o r y r e c o v e r y and m e t a b o l i t e c l a s s i f i c a t i o n i s g i v e n i n Table I I I , w h i c h showed the m e t a b o l i t e p a t t e r n i n human and monkey u r i n e t o be n e a r l y i d e n t i c a l . 1 4

1 4

Table I I I . Comparison o f E x c r e t i o n P r o f i l e s and M e t a b o l i t e C l a s s i f i c a t i o n i n Various Species

% 1 4 c -- E x c r e t i o n Urine Feces

% Metabolite Class HEEA DEA

Rat

50

50

35

65

Mouse

35

65

40

60

Monkey

88

12

80

20

Human

—

—

80

20

The rodent and monkey metabolism s t u d i e s i n d i c a t e d t h a t a l a c h l o r was r a p i d l y t r a n s f o r m e d t o a number o f m e t a b o l i t e s t h a t c o n t a i n e d d i e t h y l - a n i l i n e (DEA) and 2 - ( l - h y d r o x y e t h y l ) - e t h y l a n i l i n e (HEEA) m o i e t i e s . An a n a l y t i c a l method f o r measuring these metabol i t e s i n the u r i n e of a p p l i c a t o r s was then developed based on h y d r o l y t i c c o n v e r s i o n o f a l l m e t a b o l i t e s t o DEA and HEEA, as shown i n F i g u r e 1. The l i b e r a t e d a n i l i n e s were t h e n q u a n t i t a t e d by n e g a t i v e c h e m i c a l i o n i z a t i o n GCMS ( I n d i a n a and Canada s t u d i e s ) a f t e r convers i o n t o the c o r r e s p o n d i n g h e p t a f l u o r o b u t y r i c a n h y d r i d e (HFBA) d e r i v a t i v e s , o r d i r e c t l y by HPLC w i t h e l e c t r o c h e m i c a l detection (Missouri studies).


244


The s e n s i t i v i t y o f the methods was each m e t a b o l i t e c l a s s .

5.0

PPB,

o r 2.5

ppb

for

F i e l d Procedures Based on the monkey e x c r e t i o n s t u d i e s , a p e r i o d o f 5 days was e s t a b l i s h e d f o r c o l l e c t i o n o f a p p l i c a t o r u r i n e . Male a p p l i c a t o r s c o l l e c t e d each u r i n e v o i d i n a s e p a r a t e g l a s s b o t t l e and d e l i v e r e d the c o n t a i n e r s d a i l y t o the study a d m i n i s t r a t o r . The study admini s t r a t o r combined the v a r i o u s u r i n e v o i d s i n t o 12-hour composites f o r each a p p l i c a t o r and r e c o r d e d the d a i l y volumes. A l l samples were l a b e l e d w i t h name, date and time o f c o l l e c t i o n and s t o r e d frozen u n t i l analyzed. C o n t r o l o r b a s e l i n e u r i n e samples were c o l l e c t e d from each a p p l i c a t o r p r i o r t o the exposure study. C o n t r o l u r i n e was f o r t i f i e d i n the f i e l d w i t h r e p r e s e n t a t i v e m e t a b o l i t e s and h a n d l e d e x a c t l y as the "exposure" samples. These samples p r o v i d e d r e c o v e r y data and c o r r e c t i o n f a c t o r s t o compensate f o r any l o s s e s d u r i n g t r a n s p o r t , s t o r a g e o r a n a l y s i s . F i e l d i n f o r m a t i o n was c o l l e c t e d on s p e c i a l l y d e s i g n e d f i e l d s u r v e y forms. Data c o l l e c t e d d e s c r i b e the c o n d i t i o n s o f each a p p l i c a t i o n , and i n c l u d e d weather, a p p l i c a t i o n d e t a i l s , p e r s o n a l c l o t h i n g and h y g i e n e , wind speed and d i r e c t i o n , h u m i d i t y , type o f equipment, amount o f a l a c h l o r a p p l i e d , p r o t e c t i v e equipment ( g l o v e s , g o g g l e s ) , body w e i g h t and a number of o t h e r i t e m s . Photographs and c o n t i n u o u s v i d e o t a p e s p r o v i d e d a d d i t i o n a l documentation. F o r the M i s s o u r i and Canadian s t u d i e s , an attempt was made t o c o r r e l a t e the b i o l o g i c a l m o n i t o r i n g r e s u l t s w i t h r e s u l t s from passive dosimeters. F o r t h a t p u r p o s e , 6 gauze p a t c h e s , 10 X 10 cm were a t t a c h e d t o the c l o t h i n g n e a r the forehead ( c a p ) , back ( s h i r t ) , c h e s t ( s h i r t ) , c h e s t ( u n d e r s h i r t ) , forearm ( s l e e v e on dominant arm) and t h i g h (pant l e g ) . Care was t a k e n t o l o c a t e t h e s e so as not t o b l o c k exposed s k i n s u r f a c e s . No gauze pads were used i n the I n d i a n a study. R e s u l t s and

Discussion

R e s u l t s from r e c o v e r y experiments o f l a b o r a t o r y and f i e l d f o r t i f i c a t i o n s are shown i n T a b l e s IV ( u r i n e ) and V (gauze p a d s ) . These were used t o c o r r e c t the v a l u e s o b t a i n e d i n each c o r r e s p o n d i n g study. I n g e n e r a l , t h e r e was r e a s o n a b l e agreement between l a b o r a t o r y and f i e l d r e c o v e r i e s , i n d i c a t i n g t h a t l o s s e s were l a r g e l y due t o a n a l y t i c a l p r o c e d u r e s , not t r a n s p o r t o r s t o r a g e s t a b i l i t y factors. A summary o f data o b t a i n e d f o r a l l a p p l i c a t o r s i s shown i n T a b l e V I . The body dose i s e x p r e s s e d i n micrograms per k i l o g r a m body w e i g h t per pound a c t i v e i n g r e d i e n t a p p l i e d ( p g / k g / l b ) . This i s a c o n v e n i e n t u n i t t h a t a l l o w s e x t r a p o l a t i o n t o any number of c o n d i t i o n s when the data i s l a t e r used f o r r i s k assessment. Any one o f the b i o l o g i c a l m o n i t o r i n g v a l u e s i n T a b l e VI can be c a l c u l a t e d as f o l l o w s : The t o t a l amount o f a l a c h l o r m e t a b o l i t e s e x c r e t e d by the a p p l i c a t o r d u r i n g the days f o l l o w i n g the a p p l i c a t i o n i s o b t a i n e d by a d d i n g the v a l u e s found i n each u r i n e sample



96.2

15.3

Recov. Mean (%)

Std.

1985 = M i s s o u r i

19841 = I n d i a n a

1984C = Canada

HPLC/EC

8

95

72

2.52500

LAB 19841

GC/MS

34

No. o f S p i k e s

Dev.

10200

Fortification Range (ppb)

1984C

14.3

85.9

143

2.550

1985

20.3

18

95

48

24

100

1000

FIELD 19841

10200

1984C

8.1

85.1

18

2.525

1985

72

67

34

65.6

16

2.52500

10200

13.2

LAB 19841

1984C

11.6

87.2

141

2.550

1985

8.9

67.8

16

64

48

51000

10200

24

FIELD 19841

1984C

HEEA - Y i e l d i n g M e t a b o l i t e s

A l a c h l o r Recovery S t u d i e s - U r i n e

DEA - Y i e l d i n g M e t a b o l i e s

TABLE IV.

7.5

74.1

18

2.5250

1985

246


H

{

HYDROLYSIS

-N

H

DEA YIELDING ALACHLOR METABOLITES

HYDROLYSIS

HEEA YIELDING ALACHLOR METABOLITES F i g u r e 1. a n d HEEA.

Hydrolysis

TABLE V.

of Alachlor Metabolites

t o DEA

A l a c h l o r Recovery S t u d i e s - Gauze Pads

LAB

FIELD 1984 ( c ) 1985

1984 ( c )

1985

Fortification Range (pg)

0.01-600

0.5-5000

0.01-40

0.5-5000

No. o f S p i k e s

12

27

16

56

89.7

69.6

89.2

7.3

24.5

11.2

Recovery Mean (%)

S t d . Dev.

104

11.5

1984 = Canadian Study 1985 = M i s s o u r i Study


19. DUBELMAN AND COWELL

TABLE V I .


247

A l a c h l o r Body Dose E s t i m a t e s

Study/ A p p l i c a t o r Formul. Body Dose ( f j g / k g / l b ) A p p l i c a t o r No. Weight(kg) Oper.(1) B i o l . M o n i t . ( 2 ) P a s s i v e Dos.(3) IND IND IND IND CAN CAN

01 03 05 07 01 05

85 80 86 84 70. ,5 81. ,8

EC/MLA EC/MLA EC/MLA EC/MLA EC/MLA EC/MLA

0. 00526 0. 00574 0 0. 000676 0. 0270 0. 0199

IND IND IND IND CAN CAN MO MO MO MO

02 04 06 08 03 04 05 07 09 10

86 59 89 64 95. ,5 79. ,5 68. ,1 77. .2 63. .6 90, .8

MT/MLA MT/MLA MT/MLA MT/MLA MT/MLA MT/MLA MT/MLA MT/MLA MT/MLA MT/MLA

0. 0218 0. 0227 0. 00425 0. 00249 0.,112 0.,0405 0.,000722 0..00123 0 0..00149

0.0813 0.000153 0.000566 0.00135 0.000201

MO MO MO MO

06 08 11 12

95. .3 88. .5 79, .5 86, .3

WDG/MLA WDG/MLA WDG/MLA WDG/MLA

0..00158 0.,00231 0..000559 0

0.000268 0.000354 0.000332 0.000927

MO MO MO MO

27 28 29 30

70, .4 74, .9 74, .9 70, .4

EC/ML EC/ML EC/ML EC/ML

0 0 0,.00269 0

0 0.0000127 0.0000224 0

MO MO MO MO

25 26 31 32

77, .2 84, .0 81 .7 77 .2

MT/ML MT/ML MT/ML MT/ML

0,.000559 0,.000135 0 .000372 0 .00130

0.0000702 0.0000112 0.000184 0.000403

MO MO MO MO

33 34 35 36

81 .7 77 .2 102 .0 72 .6

WDG/ML WDG/ML WDG/ML WDG/ML

0 .000294 0 .000300 0 .000398 0 .000228

0.000118 0.000389 0.000102 0.000310

MLA = M i x e r / L o a d e r & A p p l i c a t i o n ML = M i x e r / L o a d e r Only

(1) (2) (3)

-

0.0151 0.128

1.38

IND = I n d i a n a CAN = Canada MO = M i s s o u r i

A l l US a p p l i c a t o r s a p p l i e d 80 l b a l a c h l o r t o 20 a c r e s ; Canadi a n s a p p l i e d 160 l b t o 40 a c r e s (EC) o r 150 t o 37 a c r e s (MT). C o r r e c t e d f o r 8 8 % u r i n a r y e x c r e t i o n (l4C/monkey e x c r e t i o n ) A d j u s t e d f o r 8.5% dermal a b s o r p t i o n (l4C/monkey dermal s t u d y )

American Chemical Society Library 1155 16th St. f N.VY.

Wang et al.; Biological Monitoring for Pesticide Exposure Washington, O.C. 20036 ACS Symposium Series; American Chemical Society: Washington, DC, 1988.

248


c o l l e c t e d from t h e a p p l i c a t o r . F o r example, Table V I I shows t h a t M i s s o u r i A p p l i c a t o r #10 e x c r e t e d a t o t a l o f 9.48 Mg a l a c h l o r a f t e r a p p l i c a t i o n o f 80 l b a l a c h l o r t o a 20 a c r e p l o t (4 l b / a c r e ) . T h i s v a l u e i s then c o r r e c t e d f o r t h e 88% e x c r e t o r y r e c o v e r y o b t a i n e d i n t h e C-monkey s t u d i e s , and n o r m a l i z e d f o r body weight and pounds o f a c t i v e i n g r e d i e n t a p p l i e d : 14

9.48 Mg 0.88

1

x

1

x

90 kg body weight

0.00149 Mg/kg/lb

=

80 l b a p p l i e d

The v a l u e 0.00149 Mg/kg/lb i s shown i n t h e body dose column ( b i o l . m o n i t o r i n g ) o f Table VI under a p p l i c a t o r "MO 10". The v a l u e s i n t h e n e x t column o f Table V I , i . e . , body dose from t h e p a s s i v e d o s i m e t r y s t u d i e s , a r e c a l c u l a t e d from gauze pads by m u l t i p l y i n g t h e pad v a l u e by t h e exposed body area w h i c h i t represents: 2

Body dose (Mg/kg/lb) = measured ( g / c m ) X H

body weight

(kg)

X

exposed s k i n

2

(cm )

l b applied

2

2

Areas o f exposed s k i n were 650 cm f o r t h e f a c e , 150 cm f o r the f r o n t o f t h e neck and 110 cm f o r t h e back o f t h e neck (Davies 1980). A l l o t h e r areas were assumed t o be p r o t e c t e d by the c l o t h i n g . The hands were p r o t e c t e d by rubber g l o v e s , as p e r l a b e l d i r e c t i o n s . The measured v a l u e s were c o r r e c t e d f o r t h e 8.5% dermal a b s o r p t i o n o b t a i n e d i n t h e C - d e r m a l monkey s t u d i e s , p r o d u c i n g t h e body dose v a l u e s shown i n T a b l e V I . I n h a l a t i o n was n o t measured, but was p r e v i o u s l y shown t o be n e g l i g i b l e i n comparison t o dermal 2

14

TABLE V I I .

E x c r e t i o n P r o f i l e f o r M i s s o u r i A p p l i c a t o r #10 2

1

Hours A f t e r Application 0-12 12-24 24-36 36-48 48-60 60-72 72-84 84-96 96-108 108-120

Combined* Pesticide/ Metabolite Residue (Mg/mL) 0.01414 0.00499 0.00280 N.D. N.D. N.D. N.D. N.D. N.D. N.D.

3

Volume of Urine (mL) 434 451 388 691 1214 270 809 875 1042 531

Total excreted

4

Total* Mg 6.14 2.25 1.09 0 0 0 0 0 0 0 9.48

Mg

* Results corrected f o r a n a l y t i c a l / f i e l d f o r t i f i c a t i o n recovery N.D. = n o t d e t e c t e d (LOD = 0.0025 Mg/mL) ± T o t a l Mg o b t a i n e d by m u l t i p l y i n g t h e v a l u e i n column 2 w i t h t h e c o r r e s p o n d i n g v a l u e i n column 3. i s


19.

DUBELMAN AND COWELL

249


deposition. (Lauer and A r r a s , 1982; L i b i c h , e t a l . , 1984; Lavy, 1978). There appears t o be no d i f f e r e n c e i n exposure f o r the t h r e e f o r m u l a t i o n s t e s t e d , j u d g i n g by the v a l u e s o b t a i n e d f o r m i x e r l o a d e r s ( a p p l i c a t o r s M025-M036) a p p l y i n g the e m u l s i f i a b l e concent r a t e (Lasso), microencapsulated (Lasso MT), o r water d i s p e r s i b l e g r a n u l e (Lasso WDG) f o r m u l a t i o n s . V a r i a b i l i t y w i t h i n f o r m u l a t i o n s overshadows any p o t e n t i a l d i f f e r e n c e s between f o r m u l a t i o n s , as shown i n F i g u r e 2. S i n c e each o f the s t u d i e s was performed under a d i f f e r e n t s e t of c o n d i t i o n s (open v e r s u s c l o s e d - c a b t r a c t o r , e t c . ) , average body doses were c a l c u l a t e d f o r each s e p a r a t e study. V a l u e s are shown i n Table V I I I . These v a l u e s can be used f o r r i s k assessment c a l c u l a t i o n s under any number o f assumed farm s i z e s o r c o n d i t i o n s . I t s h o u l d be n o t e d , however, t h a t t h e s e v a l u e s are a p p l i c a b l e o n l y t o a p p l i c a t o r s u s i n g s m a l l c o n t a i n e r s , 2.5 - 5.0 g a l l o n s , w h i c h are predominant i n s m a l l farms (

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