Dinocap Dermal Absorption in Female Rabbits and Rhesus Monkeys

Chapter 11

Dinocap Dermal Absorption in Female Rabbits and Rhesus Monkeys Implications for Humans Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 30, 2018 | https://pubs.acs.org Publication Date: December 23, 1988 | doi: 10.1021/bk-1988-0382.ch011

1

1

2

Stephen L. Longacre , Laura J. DiDonato , Ronald C. Wester , Howard I. Maibach , Susan S. Hurt , and Richard D. Costlow 2

1

2

1

Toxicology Department, Rohm and Haas Company, Spring House, PA 19477 Department of Dermatology, University of California School of Medicine, San Francisco, CA 94143

2

The dermal absorption of dinocap was determined in female rabbits and rhesus monkeys as part of the risk assessment for Karathane Fungicide/Miticide. C-2,4-Dinitro-6-(1-methylheptyl)phenyl crotonate (2,4-DNHPC) was used as the model isomer for dinocap in these studies. In r a b b i t s , the dermal absorption of 25 mg/kg (approximately 2500 ug/cm ) 2,4-DNHPC was 4-9%, whether 2,4-DNHPC was applied neat (undiluted) or dissolved in acetone, or applied as the wettable powder or l i q u i d concentrate formulation. The total absorption of 13 d a i l y 6-hr dermal doses of 25 mg/kg/day (2500 ug/cm /day) of neat 2,4-DNHPC in rabbits was 6%, similar to the percent absorption observed following a single dermal dose. In rhesus monkeys, the dermal absorption of 2,4-DNHPC at 2500 ug/cm (in acetone) was similar to the dermal absorption in rabbits (5%). Dermal absorption of 2,4-DNHPC in monkeys at 40 ug/cm was 16%; this dose approxmated a u s e - d i l u t i o n . The absorption data for 2,4-DNHPC in rabbits and monkeys support the conclusion that, under expected use conditions, dermal exposure to dinocap does not pose an unreasonable developmental r i s k to man. R

14

2

2

2

2

R

Dinocap (Karathane Fungicide/Miticide) was registered by Rohm and Haas Company in the United States in 1951, and is p r i n c i p a l l y used as a fungicide for control of powdery mildew and as a m i t i c i d e . Dinocap contains as i t s active ingredients a mixture of 2,4- and 2,6-dinitrooctylphenyl crotonates in an approximate 2:1 r a t i o , where "octyl" refers to a mixture of 1-methylheptyl, 1-ethylhexyl, NOTE: A more detailed version of these data will be published in a toxicology journal. 0097-6156/89/0382-0137$06.00/0 © 1989 American Chemical Society

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

Downloaded by UNIV OF MASSACHUSETTS AMHERST on May 30, 2018 | https://pubs.acs.org Publication Date: December 23, 1988 | doi: 10.1021/bk-1988-0382.ch011

138

BIOLOGICAL MONITORING FOR PESTICIDE EXPOSURE

and 1 - p r o p y l p e n t y l i s o m e r s ( F i g u r e 1 ) . S m a l l amounts o f t h e c o r r e s p o n d i n g f r e e p h e n o l s a r e a l s o p r e s e n t as a c t i v e i n g r e d i e n t s . D e v e l o p m e n t a l t o x i c i t y s t u d i e s i n New Z e a l a n d w h i t e r a b b i t s i n d i c a t e d that oral exposure to dinocap t e c h n i c a l during the p e r i o d o f o r g a n o g e n e s i s p r o d u c e d t e r a t a , w h i c h were m a n i f e s t e d as h y d r o c e p h a l u s and/or m a l f o r m a t i o n s o f t h e n e u r a l t u b e and s k u l l ( 1 ) . The n o - o b s e r v e d e f f e c t l e v e l (NOEL) and t h e minimum e f f e c t l e v e l (MEL) f o r d i n o c a p o r a l d e v e l o p m e n t a l t o x i c i t y i n r a b b i t s were j u d g e d t o be 0.5 and 3 mg/kg/day, r e s p e c t i v e l y ( 1 ) . R e s i d u e s o f d i n o c a p on c r o p s a r e s u c h t h a t t h e r i s k o f d i n o c a p t o humans by t h e o r a l r o u t e i s n e g l i g i b l e . To a s c e r t a i n t h e p o s s i b l e r i s k o f dinocap to a g r i c u l t u r a l workers, s e v e r a l s t u d i e s were p e r f o r m e d . T h e s e s t u d i e s i n c l u d e d a d i n o c a p d e r m a l / o r a l a b s o r p t i o n s t u d y i n r a b b i t s , and a d i n o c a p dermal a b s o r p t i o n s t u d y i n r h e s u s monkeys. Our o b j e c t i v e s i n t h e s e a b s o r p t i o n s t u d i e s were a) t o compare t h e p e r c e n t dermal a b s o r p t i o n o f d i n o c a p i n t h e r a b b i t and r h e s u s monkey a t dose l e v e l s used i n r a b b i t d i n o c a p t o x i c o l o g y s t u d i e s , and b) t o d e t e r m i n e t h e p e r c e n t dermal a b s o r p t i o n i n t h e r h e s u s monkey a t p o t e n t i a l worker e x p o s u r e c o n c e n t r a t i o n s . To f a c i l i t a t e t h e i n t e r p r e t a t i o n o f t h e d a t a , t h e a b s o r p t i o n s t u d i e s were p e r f o r m e d u s i n g C - 2 , 4 - d i n i t r o - 6 ( 1 - m e t h y l h e p t y l ) - p h e n y l c r o t o n a t e (2,4-DNHP'C) as t h e model compound f o r the alkyl s u b s t i t u t e d isomers of dinocap (Figure 2 ) . M a t e r i a l s and Methods T e s t Compounds. C-2,4-DNHPC (7.58 mCi/g; r a d i o p u r i t y = 96.5%; m o l e c u l a r w e i g h t = 256 g / m o l e ) , and n o n r a d i o l a b e l e d 2,4-DNHPC p u r i t y = 97%) used t o d i l u t e t h e s p e c i f i c a c t i v i t y o f t h e 4C-2,4-DNHPC, were b o t h s y n t h e s i z e d a t Rohm and Haas Company ( S p r i n g House, P A ) . The t e s t compounds were l i g h t amber c o l o r e d oils. A n i m a l s . F e m a l e New Z e a l a n d w h i t e r a b b i t s (34-42 weeks o l d ; 2.9-3.9 kg; H a z l e t o n D u t c h l a n d ; Denver, P A ) , and f e m a l e r h e s u s monkeys (5.4-10.7 kg; U n i v e r s i t y o f C a l i f o r n i a a t D a v i s P r i m a t e C e n t e r ; D a v i s , CA) were used i n t h e s e s t u d i e s (3 o r 4 a n i m a l s p e r group). 14 Rabbit Intravenous Study. C-2,4-DNHPC, d i s s o l v e d i n d i m e t h y l s u l f o x i d e (DMSO), was a d m i n i s t e r e d i n t h e j u g u l a r v e i n (0.1 m l / k g ) at 3 mg/kg (3 u C i / k g ) . U r i n e and f e c e s were c o l l e c t e d a t i n t e r v a l s up t o 4 days a f t e r d o s i n g and a n a l y z e d f o r t o t a l ' C - l a b e l . A l l r a b b i t s were h u m a n e l y k i l l e d by an i n t r a c a r d i a c i n j e c t i o n o f e u t h a n a s i a s o l u t i o n (T-61 ; A m e r i c a n H o e c h s t C o r p . , S o m e r v i l l e , NJ). R a b b i t O r a l S t u d i e s . C-2,4-DNHPC, s u s p e n d e d i n aqueous 1% gum t r a g a c a n t h , was a d m i n i s t e r e d by gavage (5 m l / k g ) a t 0.5, 3, o r 25 mg/kg (3-17 u C i / k g ) . U r i n e , f e c e s , and p l a s m a were c o l l e c t e d at i n t e r v a l s up t o 4 days a f t e r d o s i n g and a n a l y z e d f o r ^ C - l a b e l . R a b b i t 6 Hr Dermal E x p o s u r e S t u d i e s . The f u r on t h e d o r s a l s i d e o f e a c h r a b b i t was c l i p p e d t o e x p o s e an a r e a o f a p p r o x i m a t e l y 280 cm 1-3 days p r i o r t o d o s i n g . P l a s t i c c o l l a r s were p l a c e d on e a c h rabbit to prevent preening of the application site.p C-2,4-DNHPC (23-31 u C i / k g ) was a p p l i e d d i r e c t l y o n t o a 5 x 8 cm a r e a o f t h e 14

4

14

4

2



LONGACRE ET AL.

Dinocap Dermal Absorption

F i g u r e 1. S t r u c t u r a l f o r m u l a e o f t h e a c t i v e i n g r e d i e n t components o f d i n o c a p [ 2 , 4 - d i n i t r o o c t y l p h e n y l c r o t o n a t e s ( t o p ) and 2 , 6 - d i n i t r o o c t y l p h e n y l c r o t o n a t e s ( b o t t o m ) ] ; "n" e q u a l s 0, 1, and 2.

F i g u r e 2. S t r u c t u r a l f o r m u l a o f C-2,4-DNHPC; t h e a s t e r i s k s indicate location of the C-label.


140

BIOLOGICAL MONITORING FOR PESTICIDE EXPOSURE

c l i p p e d d o r s a l s i t e as a) t h e n e a t ( u n d i l u t e d ) m a t e r i a l a t 25 ( 2 . 2 ) , 100 ( 8 . 3 ) , and 220 mg/kg ( 1 8 . 3 mg/cra ); b) t h e w e t t a b l e d u s t (WD) f o r m u l a t i o n a t 25 mg a i / k g (2.4 mg/cm ) a p p l i e d as a 2 0 . 4 % a i p a s t e (1:1.3 p a s t e : w a t e r ) a t 0.28 g p a s t e / k g ; c ) t h e l i q u i d c o n c e n t r a t e ( L C ) f o r m u l a t i o n a t 25 mg a i / k g ( 2 . 5 mg/cm a p p l i e d as a 3 9 . 8 % a i s o l u t i o n ( 0 . 0 6 m l / k g ) ; o r d) i n a c e t o n e a t 25 mg/kg (2.2 mg/cm ) a p p l i e d as a 3 9 . 8 % a i s o l u t i o n ( 0 . 0 6 m l / k g ) . S i x ( 6 ) h r a f t e r d o s e a p p l i c a t i o n , t h e a p p l i c a t i o n s i t e s were w i p e d w i t h gauze pads s o a k e d w i t h aqueous 9 5 % e t h a n o l , f o l l o w e d by w i p i n g w i t h pads s a t u r a t e c L w i t h w a t e r . A p p l i c a t i o n s i t e s o f r a b b i t s t r e a t e d w i t h t h e C-2,4-DNHPC-WD f o r m u l a t i o n were w i p e d w i t h d i s t i l l e d w a t e r o n l y . The w i p e s were e x t r a c t e d w i t h a c e t o n e and a n a l y z e d f o r t o t a l C - l a b e l . U r i n e , f e c e s , and p l a s m a were c o l l e c t e d a t i n t e r v a l s up t o 7 d a y s and a n a l y z e d f o r ^ C - l a b e l . A t t e r m i n a t i o n , t h e a p p l i c a t i o n s i t e s k i n s were c o l l e c t e d , d i s s o l v e d i n t i s s u e s o l u b i l i z e r ( U n i s o l ; I s o l a b I n c . ; A k r o n , OH), and analyzed f o r t o t a l C-label. z


2

4

R

14

R a b b i t 7 Day ( L e a v e - O n ) Dermal E x p o s u r e S t u d y . C-2,4-DNHPC was a p p l i e d d e r m a l l y as t h e n e a t m a t e r i a l a t 25 mg/kg (2.1 mg/cm ; 30 u C i / k g ) , and was l e f t on f o r 7 d a y s . U r i n e , f e c e s , and p l a s m a were c o l l e c t e d a t i n t e r v a l s o v e r t h e 7-day p e r i o d and a n a l y z e d f o r C - l a b e l . A t t e r m i n a t i o n , . t h e a p p l i c a t i o n s i t e s k i n s were c o l l e c t e d and a n a l y z e d f o r C - l a b e l . The a p p l i c a t i o n s i t e s were not w i p e d p r i o r t o ' C - a n a l y s i s o f t h e s k i n , s i n c e a l a r g e amount o f f u r had grown b a c k . R a b b i t M u l t i p l e Dermal Dose S t u d y . Neat C-2,4-DNHPC was a p p l i e d as 13 d a i l y 6 h r d o s e s a t 25 mg/kg/day. T h e 5 x 8 cm a p p l i c a t i o n a r e a was r o t a t e d among 7 s i t e s s u c h t h a t c o n s e c u t i v e d o s e s were n o t a p p l i e d t o t h e same o r . a d j a c e n t s i t e s . The a p p l i c a t i o n s i t e s were wiped 6 hr a f t e r each C-dose a p p l i c a t i o n , and t h e w i p e s were a n a l y z e d f o r C - l a b e l . U r i n e , f e c e s , and p l a s m a were c o l l e c t e d a t i n t e r v a l s d u r i n g t h e 13 d a y d o s i n g p h a s e and f o r up t o 10 days a f t e r t h e l a s t d o s e , and a n a l y z e d f o r ' C - l a b e l . R a b b i t s were k i l l e d 10 days a f t e r t h e l a s t d o s e , and t h e a p p l i c a t i o n s i t e s were c o l l e c t e d and a n a l y z e d f o r ^ C - l a b e l . 4

14

4

4

14

Monkey I n t r a v e n o u s S t u d y . C-2,4-DNHPC d i s s o l v e d i n DMS0, was a d m i n i s t e r e d i n t h e f e m o r a l v e i n (0.1 m l / k g ) a t 0.2 mg/kg (0.15 u C i / k g ) . P l a s m a was c o l l e c t e d a t i n t e r v a l s up t o 2 days a f t e r d o s i n g , w h i l e u r i n e and f e c e s were c o l l e c t e d a t i n t e r v a l s up t o 4 days a f t e r d o s i n g and a n a l y z e d f o r C - l a b e l . F e c a l s a m p l e s were p o o l e d p r i o r t o a n a l y s i s . T h e s e a n i m a l s were u s e d i n s u b s e q u e n t dermal s t u d i e s o n c e . i t was d e t e r m i n e d t h a t p l a s m a and u r i n e c o n t a i n e d no r e s i d u a l C-label. Monkey P e r c u t a n e o u s S t u d y (40 u g / c m ) . C-2,4-DNHPC, d i s s o l v e d i n 400 u l a c e t o n e , was a p p l i e d t o 40 c m o f a b d o m i n a l s k i n a t 40 ug/cm ( 1 . 6 mg/monkey; a p p r o x i m a t e l y 0.2 mg/kg; 12 u C i / m o n k e y ) . The a n i m a l s were r e s t r a i n e d i n m e t a b o l i c c h a i r s d u r i n g t h e dermal e x p o s u r e p e r i o d , and were r e t u r n e d t o m e t a b o l i c c a g e s i m m e d i a t e l y f o l l o w i n g t h e dose wipe-off. T h e a p p l i c a t i o n s i t e s were wiped w i t h c o t t o n b a l l s l a d e n e d w i t h w a t e r , o r w i t h aqueous 9 5 % e t h a n o l f o l l o w e d by a w a t e r r i n s e 6 h r a f t e r a p p l i c a t i o n ; t h e w i p e s were 2

14

2


11. LONGACREETAL.

141


a n a l y z e d f o r 1 ^ C - 1 a b e l . P l a s m a was c o l l e c t e d a t i n t e r v a l s up t o 2 d a y s , w h i l e u r i n e and f e c e s were c o l l e c t e d a t i n t e r v a l s up t o 4 days and a n a l y z e d f o r C - l a b e l . Monkey P e r c u t a n e o u s S t u d y (2500 u g / c m ) . C-2,4-DNHPC d i s s o l v e d i n 14 u l a c e t o n e , was a p p l i e d t o 0.64 cm o f a b d o m i n a l s k i n a t 2500 ug/ciTr ( 1 . 6 mg/monkey; a p p r o x i m a t e l y 0.2 mg/kg; 12 u C i / m o n k e y ) . The a p p l i c a t i o n s i t e s were w i p e d w i t h aqueous 9 5 % e t h a n o l , f o l l o w e d by w a t e r , 6 h r a f t e r dose a p p l i c a t i o n ; t h e w i p e s were a n a l y z e d f o r C - l a b e l . P l a s m a was c o l l e c t e d a t i n t e r v a l s up t o 2 d a y s , w h i l e u r i n e and f e c e s were c o l l e c t e d a t i n t e r v a l s up t o 4 days and analyzed f o r C - l a b e l . P e r c e n t A b s o r p t i o n . The f r a c t i o n o f an o r a l o r dermal dose o f i4C-2,4-DNHPC a b s o r b e d r e p r e s e n t e d t h e u r i n a r y 1 4 c - e x c r e t i o n a f t e r o r a l o r dermal a d m i n i s t r a t i o n d i v i d e d b y t h e u r i n a r y ^ C - e x c r e t i o n after i v administration (2, 3 ) . 1 4


2

14

1

4

Results R a b b i t I n t r a v e n o u s S t u d y . Most (58-85%) o f an i v d o s e o f ' C-2,4-DNHPC was e x c r e t e d f r o m r a b b i t s w i t h i n 24-48 h r ( F i g u r e 3 ) . Urinary C - e x c r e t i o n was 5 - f o l d g r e a t e r t h a n f e c a l e x c r e t i o n ; 7 3 % o f t h e d o s e was r e c o v e r e d i n t h e u r i n e b y 96 h r . R a b b i t O r a l S t u d i e s . The p e r c e n t a b s o r p t i o n o f an o r a l dose o f 14C-2,4-DNHPC (0.5-25 mg/kg) was 60-69% { T a b l e I ) . P r a c t i c a l l y a l l o f an o r a l dose o f C-2,4-DNHPC was e l i m i n a t e d i n t h e e x c r e t a o f r a b b i t s w i t h i n 48 h r ( F i g u r e 3 ) . T h e p e r c e n t c u m u l a t i v e u r i n a r y and f e c a l C - e x c r e t i o n . w e r e each s i m i l a r among t h e t h r e e o r a l d o s e g r o u p s . F e c a l C-excretion ( 5 7 - 7 2 % o f d o s e ) was s l i g h t l y g r e a t e r t h a n u r i n a r y ^ C - e x c r e t i o n ( 3 5 - 5 1 % o f d o s e ) b y 96 h r . ' C-2,4-DNHPC-derived C - l a b e l was r a p i d l y a b s o r b e d a f t e r o r a l a d m i n i s t r a t i o n , r e a c h i n g peak p l a s m a C-concentrations within 1-3 h r ( T a b l e I I ) . Peak p l a s m a ^ - c o n c e n t r a t i o n was p r o p o r t i o n a l t o d o s e ( T a b l e I I ) . E l i m i n a t i o n o f C - l a b e l was b i p h a s i c f o r a l l g r o u p s ; a r a p i d e l i m i n a t i o n p h a s e ( t 1/2 = 2.2-3.8 h r ) , l a s t i n g a p p r o x i m a t e l y 24 h r a f t e r d o s i n g , p r e c e d e d a s l o w e r t e r m i n a l e l i m i n a t i o n p h a s e ( t 1/2 = 33.3-55.1 h r ) . +#

1

4

4

1 4

R a b b i t 6 Hr Dermal E x p o s u r e S t u d i e s . The p e r c e n t a b s o r p t i o n o f a 6 h r dermal e x p o s u r e o f C-2,4-DNHPC was 4-9%, r e g a r d l e s s o f t h e dose o r t h e f o r m u l a t i o n / v e h i c l e ( T a b l e I ) . A m a j o r i t y o f t h e a p p l i e d 1 C-2,4-DNHPC ( 6 0 - 9 5 % o f d o s e ; 89-95% o f r e c o v e r e d C - l a b e l ) was r e c o v e r e d i n t h e 6 h r w i p e - o f f r e g a r d l e s s o f t h e dose o r t h e f o r m u l a t i o n / v e h i c l e ( T a b l e I I I ) . Little C - l a b e l ( 0 . 0 2 - 1 % o f d o s e ) was r e c o v e r e d i n t h e a p p l i c a t i o n s i t e s k i n s a t t h e end o f t h e 7-day i n - l i f e p b a s e ( T a b l e I I I ) . A t o t a l o f 5-12% o f a 6 h r dermal e x p o s u r e o f C-2,4-DNHPC was e l i m i n a t e d i n t h e e x c r e t a w i t h i n 7 d a y s r e g a r d l e s s o f t h e dose or t h e f o r m u l a t i o n / v e h i c l e (Table I I I ) . A l s o , t h e percent c u m u l a t i v e u r i n a r y and f e c a l ' C - e x c r e t i o n were c o m p a r a b l e among t h e dermal g r o u p s , r e g a r d l e s s o f t h e d o s e o r t h e f o r m u l a t i o n / v e h i c l e . Most o f t h e e x c r e t e d C - l a b e l was e l i m i n a t e d w i t h i n 2-4 days ( F i g u r e 3 ) , and was e s s e n t i a l l y e v e n l y d i s t r i b u t e d between t h e u r i n e and f e c e s . 14

4

14

4

1 4


142

BIOLOGICAL MONITORING FOR PESTICIDE EXPOSURE Table I .

mg/kg

Dose ug/cm

2

n

14

P e r c e n t A b s o r p t i o n o f C-2,4-DNHPC i n Female R a b b i t s and Rhesus Monkeys

Route

Exposure Time

Formulation/ Vehicle

Percent Absorption

Rabbit


3 0.5 3 25

— — — —

3

iv

4 3 4

Oral Oral Oral

— — — —

Gum T r a g Gum T r a g Gum T r a g

3 1 2

Neat

13 +

6

Neat

6 +

1

Dermal Dermal Dermal

6 Hr 6 Hr 6 Hr

25 25 25

2390 2450 2220

3 3 4


6 Hr 6 Hr 6 Hr

25

2060

4

Dermal

4

Dermal

4

iv

—

DMSO

7 Day

69 + 29 60 + 4 64 + 6

9 + 4 + 7 +

3 3 3

6 Hr ( x l 3 )

6

2 3 4

2150 8310 18,300

1850-2313

b

4 + 5 + 5 +

25 100 220

25

100 +

DMSO

Neat Neat Neat WD LC Acetone

Monkey 0.2

—

100 + 16

0.2

40

8

Dermal

6 Hr

Acetone

16 +

7

0.2

2500

4

Dermal

6 Hr

Acetone

5 +

3

P e r c e n t a b s o r p t i o n (% o f d o s e ) ; mean + s t a n d a r d d e v i a t i o n . One

(1) p e r c e n t gum t r a g a c a n t h

suspension.

F i g u r e 3. C u m u l a t i v e e x c r e t i o n o f C - l a b e l i n t h e u r i n e ( O h f e c e s ( • ) , and combined u r i n e and f e c e s ( • ) o f f e m a l e r a b b i t s a d m i n i s t e r e d a n ^ v , o r a l , 6 h r d e r m a l , o r 7-day ( l e a v e - o n ) dermal dose o f C-2,4-DNHPC.


a

11. LONGACRE ET AL.

143


1 4

Table I I .

Peak P l a s m a C - C o n c e n t r a t i o n i n Female R a b b i t s and Rhesus Monkeys A d m i n i s t e r e d C-2,4-DNHPC


14

Dose mg/kg u g / c m

2

Exposure Route Time

Formulation/ Vehicle n

1 4

Peak P l a s m a C-Concentration (ppm) (hr)

Rabbit

— — —

0. 5 3 25

Oral Oral Oral

— — —

Gum Gum Gum

Trag Trag Trag

4 3 4

0.29 + 0.04 1.26 + 0.42 14.55 + 6.62

1 3 3

3 3 3

0.15 + 0.05 0.47 + 0.10 1.51 + 1.12

6 24

3 3 4

0.19 + 0.03 0.24 + 0.07 0.28 + 0.00

24 6 24

25 100 220

2150 8310 18i,300


6 Hr 6 Hr 6 Hr

25 25 25

2390 2450 2220


6 Hr 6 Hr 6 Hr

25

2060

Dermal

7 Day

Neat

4

0.24 + 0.19

6

18502313

Dermal

6 Hr (xl3)

Neat

4

0.89

+ 0.33

318

25 (X13)

Neat Neat Neat

b

WD LC Acetone

Monkey

a

0

Dinocap Dermal Absorption in Female Rabbits and Rhesus Monkeys

Recommend Documents