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Chlorinated dioxin and dibenzofuran levels in sediments collected from rivers in Vietnam, 1984-6
Chemosphere, Vol.18, Nos.l-6, Printed in Great Britain
pp 831-834,
1989
0045-6535/89 $3.00 + .00 Peraamon Press plc
C H L O R I N A T E D DIOXIN AND D I B E N Z O F U R A N LEVELS IN SEDIMENTS COLLECTED FROM RIVERS IN VIETNAM, 1984-6
A r n o l d Schecter 1, Brian D. Eitzer, and Ronaid A. Hites 2" IDept. of Preventive Medicine, Clinical Campus, State U n i v e r s i t y of New York, 88 Aldrich Ave., Binghamton, NY
13903
2School of Public and E n v i r o n m e n t a l A f f a i r s and D e p a r t m e n t of Chemistry, I n d i a n a University, Bloomington, IN 47405 A b s t r a c t . G r a b s e d i m e n t s a m p l e s w e r e t a k e n f r o m t h r e e r i v e r s in V i e t n a m ; t h e s e s a m p l e s r e p r e s e n t e d t h e i n d u s t r i a l s o u t h ( S a i g o n R i v e r ) , t h e A g e n t O r a n g e s p r a y e d a r e a ( D u n g Nai River) and the n o n - i n d u s t r i a l north (Red River). Samples were analyzed for the tetra- through octa- chloro-homologs of polychlorinated dibenzo-p-dioxins and furans (PCDD/F). The homologs were present in p a t t e r n s a n d amounts previously seen for e n v i r o n m e n t a l samples. Introduction. A n u m b e r of recent studies have focused on the presence of P C D D / F in human a d i p o s e t i s s u e (]-6). T h e s e s t u d i e s h a v e r e s u l t e d in m u c h s p e c u l a t i o n a b o u t t h e s o u r c e of t h e s e c o m p o u n d s to h u m a n s . Possible sources include direct contamination of the environment by i n d u s t r i a l d i s c h a r g e s or s p r a y i n g of P C D D / F c o n t a i n i n g m a t e r i a l s s u c h as A g e n t O r a n g e or i n d i r e c t c o n t a m i n a t i o n by t h e p r o d u c t i o n a n d e m i s s i o n of t h e s e c o m p o u n d s d u r i n g c o m b u s t i o n followed by a t m o s p h e r i c t r a n s p o r t and deposition. Of
the recent studies on adipose tissue, one focused on V i e t n a m .
This
study
compared
P C D D / F l e v e l s in b o t h t h e n o r t h a n d s o u t h of V i e t n a m w i t h the l e v e l s r e p o r t e d f r o m o t h e r industrialized countries (4). It was f o u n d that the industrialized south had levels c o m p a r a b l e to or h i g h e r t h a n o t h e r i n d u s t r i a l i z e d c o u n t r i e s , a n d t h e more r u r a l N o r t h had levels which were an order of magnitude less. Thus, studies which compare the North and South of Vietnam might shed some light onto the source of these compounds to the e n v i r o n m e n t and, ultimately, the h u m a n population. It h a s b e e n s h o w n t h a t s e d i m e n t s c a n p r o v i d e a r c h i v e s o f e n v i r o n m e n t a l p o l l u t i o n t r e n d s P C D D / F have been f o u n d in sediment at remote sites at low concentrations (8), indicating that sediment can be used to study the atmospheric transport of these compounds. Thus, in an a t t e m p t to u n d e r s t a n d d i f f e r e n c e s in P C D D / F c o n t a m i n a t i o n in V i e t n a m , it was of i n t e r e s t to compare sediment from various areas in Vietnam.
(7).
ExPerimental. S e d i m e n t was o b t a i n e d f r o m t h r e e r i v e r s in V i e t n a m w h i c h are s h o w n in F i g u r e 1. T h e s a m p l i n g l o c a t i o n s a r e the S a i g o n R i v e r in the Ho Chi Mirth C i t y a r e a ( p o p u l a t i o n 2,700,800), f o r m e r l y S a i g o n , f o l l o w e d by f i v e s i t e s a l o n g t h e D o n g Nai r i v e r in the heavily c o n t a m i n a t e d (by Agent Orange) area a r o u n d Tan Uyen village, and two sites in the Red River, in the Hanoi area (population 880,000), where Agent Orange was never used. At each location, grab samples were taken from the bottom of the river by a diver. T h e e x p e r i m e n t a l p r o c e d u r e has been r e p o r t e d e l s e w h e r e (9). It c o n s i s t s of s p i k i n g the sediment with carbon-13 labeled OCDD, soxhlet extraction, chromatographic clean-up, and GC/MS in the e l e c t r o n c a p t u r e , n e g a t i v e i o n i z a t i o n mode u s i n g s e l e c t e d ion m o n i t o r i n g . It s h o u l d be n o t e d t h a t t h i s i o n i z a t i o n m o d e g i v e s a p o o r r e s p o n s e f o r 2 , 3 , 7 , 8 - T C D D , b u t it r e s p o n d s well for all the other congeners (including other tetras).
831
832
Figure I. Map of Vietnam showing the Dong Nai River, Saigon River, and Red R i v e r about 1140 km from Hanoi to Ho Chi Minh City.
l!
is
833
Results and Discussion. The results of the study are shown in Table 1. An e x a m i n a t i o n of t h i s t a b l e s h o w s t h a t t h e c o n c e n t r a t i o n l e v e l s in a g i v e n s a m p l e d i f f e r d r a m a t i c a l l y f r o m one another but that the relative amounts of the various chloro-homologs w i t h i n a given sample are quite similar to one another. For example, all samples have OCDD as highest homolog but its concentration ranges from 210-4530 pg/g. T h e s e d a t a show t h e h i g h e s t c o n c e n t r a t i o n s in the Saigon R i v e r , m e d i u m c o n c e n t r a t i o n s in t h e D o n g N a i R i v e r , a n d t h e l o w e s t c o n c e n t r a t i o n s in the Red River. The overall p a t t e r n of P C D D / F chloro-homoiogs is one which might be related to c o m b u s t i o n p r o c e s s e s f o l l o w e d by a t m o s p h e r i c d e p o s i t i o n . T h e p a t t e r n of c h i o r o - h o m o l o g s is also similar to what was seen in the h u m a n f a t tissue from Vietnam previously reported (4).
TABLE 1 VIETNAM SEDIMENT CONCENTRATIONS IN PG/G DRY VEIGHT OF PCDD/F FROM RIVERS IN THE NORTH AND SOUTH OF VIETNAM, 1984/5
SAMPLE
TCDD PnCDD HxCDD HpCDD OCDD
Saigon R i v e r
--
87
220
Dang Nai R i v e r 1
-*
6.8
33
120
1200
Dang Nai R i v e r 2
--
4.2
11
68
750
11
Pang Rat R i v e r 3
--
6.7
17
140
1200
18
Dong Nai R i v e r 4
--
t.2
Dang Nai R i v e r 5
*-
0.9
Red R i v e r #1 Red R i v e r ~2
. . . . . . . .
8.2 13 0.5 0.9
940
TCDF
4530
PnCDF H x C D F
55 .
.
160 .
.
240 .
3.2 14
320
4.1 8.4
63
950
16
4.1
1120
11
4.0
25
0.4 0.4
---
240 210
2.6 1.8
230
.
160 10 5.1
NpCDF OCDF
2.8
2.2
3.1
2.9
21
2.1
3.3 48 1.0 0.4
12 4.1 51 0.9 0.8
TOTAL
6782 1365 858 1437 1052 1433 255 219
A BLANK INDICATES THAT THE ROMOLOG GROUP WAS NOT DETECTED AT A LIMIT OF DETECTION OF ABOUT 0.1 PG/G
TABLE 2 AVERAGE TOTAL CONCENTRATIONS OF PCDD/F |N PG/G FOR UPPERMOST LARE SEDIMENTSa AND VIETNAM RIVER SEDIMENTSb ~ietnem R i v e r s Sediments
Lake SedimenTs Site
Cone.
Site
Conc.
Lake Nuron
1240
Ssigo~
6800
Lake Michigan
1600
Dons Uai
1200
Lake E r i e
2150
Red R i v e r
Lake O n t a r i o S t s k t w l t Lake Lake Z u r i c h Lake | a L d e r s Lake L w s n o
11000 7"50 1500 1500 2000
a)
From J. M. Czuczve, Ph.D. Thesis (Reference I 1 0 )
b)
This s t u d y
240
834
In Table 2, the total average concentrations of P C D D / F are compared to the concentrations f r o m t h e u p p e r m o s t l a y e r of l a k e s e d i m e n t s p r e v i o u s l y r e p o r t e d (10). T h i s c o m p a r i s o n is not exact because river sediments reflect conditions upstream and lake sediments reflect conditions over most of the lake's watershed. E v e n so, it c a n be s e e n t h a t the S a i g o n R i v e r has c o n c e n t r a t i o n s o n l y e x c e e d e d b y L a k e O n t a r i o w h i c h is t h o u g h t to h a v e some direct c o n t a m i n a t i o n by P C D D / F f r o m p e n t a c h l o r o p h e n o l w a s t e s (10). T h u s , t h e S a i g o n R i v e r , in a h e a v i l y i n d u s t r i a l i z e d a r e a in w h i c h b o t h d i r e c t a n d i n d i r e c t c o n t a m i n a t i o n m i g h t be e x p e c t e d , has t h e h i g h e s t c o n c e n t r a t i o n a m o n g t h e V i e t n a m r i v e r s s t u d i e d . T h e n e x t h i g h e s t level of c o n c e n t r a t i o n is t h a t o f t h e D o n g N a i R i v e r . H e r e , the c o n c e n t r a t i o n s a r e s i m i l a r to lakes which are near industrial areas and receive considerable atmospheric input. As can be seen in Figure 1, the entire Dong Nai River is within 200 km of the industrialized area of Ho Chi Mirth C i t y , a n d t h u s , m i g h t be e x p e c t e d to r e c e i v e a t m o s p h e r i c d e p o s i t i o n o f P C D D / F . T h e lowest level o f c o n c e n t r a t i o n is t h a t seen in the Red R i v e r . T h i s level is e v e n less t h a n t h a t seen in the v e r y r e m o t e S i s k i w i t L a k e . A l t h o u g h t h i s is s o m e w h a t s u r p r i s i n g c o n s i d e r i n g the a r e a ' s p o p u l a t i o n (880,000), t h e s e low P C D D / F c o n c e n t r a t i o n s m i g h t be i n d i c a t i v e of conditions upstream. It s h o u l d be p o i n t e d o u t t h a t the H a n o i a r e a is not heavily industrialized and that the Hanoi area is where the lowest h u m a n adipose tissue levels of P C D D / F were seen. That TCDD was not f o u n d at any site, including Agent Orange sprayed areas, could have several explanations. F i r s t , s a m p l i n g s i t e s were g r a b s a m p l e s of the u p p e r m o s t s e d i m e n t , a n d TCDD c o n t a m i n a t e d material could have been buried by fresh sediment. It is also possible that the poor i n s t r u m e n t a l r e s p o n s e f o r 2 , 3 , 7 , 8 - T C D D in the n e g a t i v e i o n i z a t i o n m o d e p r e v e n t s its detection. To s u m m a r i z e , it h a s b e e n s h o w n t h a t r i v e r s e d i m e n t s in V i e t n a m a r e c o n t a m i n a t e d w i t h PCDD/F. T h e l e v e l s o f c o n t a m i n a t i o n f r o m the d i f f e r e n t a r e a s c o r r e l a t e w i t h the l e v e l s seen in h u m a n adipose tissue from the d i f f e r e n t areas. The levels are in the range previously seen f o r lake s e d i m e n t s a n d c a n p o s s i b l y be r e l a t e d to the a t m o s p h e r i c d e p o s i t i o n of P C D D / F produced by combustion sources. REFERENCES I. M. Nygren, C. Rappe, G. Lindstrom, M. Hanson, P. A. Berqvist, S. Marklund, L. Domellof, L. H a r d e l l a n d M. O i s s o n in Chlorinated Dioxins and Dibenzo/urans in Perspective (Eds. C. Rappe, G. C h o u d h a r y and L. Keith), Lewis Publishers, pp. 17-34 (1986). 2. A. J. S c h e c t e r , J. J. R y a n , M. Gross, N. C. A. W e e r a s i n g h e , a n d J. D. C o n s t a b l e Chlorinated Dioxins and Dibenzo/urans in Perspective (Eds. C. R a p p e , G. C h o u d h a r y a n d Keith), Lewis Publishers, pp. 35-50 (1986).
in L.
3. A. S c h e c t c r , J. J. R y a n a n d G. G i t l i t z in Chlorinated Dioxins and Dibenzo/urans Perspective (Eds. C. Rappc, G. C h o u d h a r y and L. Keith), Lewis Publishers, pp. 51-64 (1986).
in
4.
A.J. Schccter, J. J. Ryan and J. D. Constable, Chemosphere 15, l113-1670 (1986).
5.
M. Ono, T. Wakimoto, R. T a t s u k a w a and Y. Masuda, Chemosphere 15, 1629-1684 (1986).
6.
C. Rappc, M. Nygren, G. Lindstrom, and M. Hanson, Chemosphere 15, 1635-1639 (1986).
7. M. J. Charles and R. A. Hitcs in Sources and Fates of Aquatic and S. J. Eisenrcich), A m e r i c a n Chemical Society, pp. 365-392 (1987).
8.
J. M Czuczwa, B. D. McVccty, and R. A. Hires, Science 226, 568-569 (1984).
9.
J.M. Czuczwa and R. A. Hites, Environ. ScL Technol. 18, 444-450 (1984).
Pollutants
(Eds.
R.
A. Hires
lO. J. M, Czuczwa, The e n v i r o n m e n t a l fate o f c o m b u s t i o n - g e n e r a t e d p o l y c h l o r i n a t e d dibcnzo-Rdioxins and dibenzofurans. Ph.D, Thesis, Indiana University, Bloomington (1984).
pp 831-834,
1989
0045-6535/89 $3.00 + .00 Peraamon Press plc
C H L O R I N A T E D DIOXIN AND D I B E N Z O F U R A N LEVELS IN SEDIMENTS COLLECTED FROM RIVERS IN VIETNAM, 1984-6
A r n o l d Schecter 1, Brian D. Eitzer, and Ronaid A. Hites 2" IDept. of Preventive Medicine, Clinical Campus, State U n i v e r s i t y of New York, 88 Aldrich Ave., Binghamton, NY
13903
2School of Public and E n v i r o n m e n t a l A f f a i r s and D e p a r t m e n t of Chemistry, I n d i a n a University, Bloomington, IN 47405 A b s t r a c t . G r a b s e d i m e n t s a m p l e s w e r e t a k e n f r o m t h r e e r i v e r s in V i e t n a m ; t h e s e s a m p l e s r e p r e s e n t e d t h e i n d u s t r i a l s o u t h ( S a i g o n R i v e r ) , t h e A g e n t O r a n g e s p r a y e d a r e a ( D u n g Nai River) and the n o n - i n d u s t r i a l north (Red River). Samples were analyzed for the tetra- through octa- chloro-homologs of polychlorinated dibenzo-p-dioxins and furans (PCDD/F). The homologs were present in p a t t e r n s a n d amounts previously seen for e n v i r o n m e n t a l samples. Introduction. A n u m b e r of recent studies have focused on the presence of P C D D / F in human a d i p o s e t i s s u e (]-6). T h e s e s t u d i e s h a v e r e s u l t e d in m u c h s p e c u l a t i o n a b o u t t h e s o u r c e of t h e s e c o m p o u n d s to h u m a n s . Possible sources include direct contamination of the environment by i n d u s t r i a l d i s c h a r g e s or s p r a y i n g of P C D D / F c o n t a i n i n g m a t e r i a l s s u c h as A g e n t O r a n g e or i n d i r e c t c o n t a m i n a t i o n by t h e p r o d u c t i o n a n d e m i s s i o n of t h e s e c o m p o u n d s d u r i n g c o m b u s t i o n followed by a t m o s p h e r i c t r a n s p o r t and deposition. Of
the recent studies on adipose tissue, one focused on V i e t n a m .
This
study
compared
P C D D / F l e v e l s in b o t h t h e n o r t h a n d s o u t h of V i e t n a m w i t h the l e v e l s r e p o r t e d f r o m o t h e r industrialized countries (4). It was f o u n d that the industrialized south had levels c o m p a r a b l e to or h i g h e r t h a n o t h e r i n d u s t r i a l i z e d c o u n t r i e s , a n d t h e more r u r a l N o r t h had levels which were an order of magnitude less. Thus, studies which compare the North and South of Vietnam might shed some light onto the source of these compounds to the e n v i r o n m e n t and, ultimately, the h u m a n population. It h a s b e e n s h o w n t h a t s e d i m e n t s c a n p r o v i d e a r c h i v e s o f e n v i r o n m e n t a l p o l l u t i o n t r e n d s P C D D / F have been f o u n d in sediment at remote sites at low concentrations (8), indicating that sediment can be used to study the atmospheric transport of these compounds. Thus, in an a t t e m p t to u n d e r s t a n d d i f f e r e n c e s in P C D D / F c o n t a m i n a t i o n in V i e t n a m , it was of i n t e r e s t to compare sediment from various areas in Vietnam.
(7).
ExPerimental. S e d i m e n t was o b t a i n e d f r o m t h r e e r i v e r s in V i e t n a m w h i c h are s h o w n in F i g u r e 1. T h e s a m p l i n g l o c a t i o n s a r e the S a i g o n R i v e r in the Ho Chi Mirth C i t y a r e a ( p o p u l a t i o n 2,700,800), f o r m e r l y S a i g o n , f o l l o w e d by f i v e s i t e s a l o n g t h e D o n g Nai r i v e r in the heavily c o n t a m i n a t e d (by Agent Orange) area a r o u n d Tan Uyen village, and two sites in the Red River, in the Hanoi area (population 880,000), where Agent Orange was never used. At each location, grab samples were taken from the bottom of the river by a diver. T h e e x p e r i m e n t a l p r o c e d u r e has been r e p o r t e d e l s e w h e r e (9). It c o n s i s t s of s p i k i n g the sediment with carbon-13 labeled OCDD, soxhlet extraction, chromatographic clean-up, and GC/MS in the e l e c t r o n c a p t u r e , n e g a t i v e i o n i z a t i o n mode u s i n g s e l e c t e d ion m o n i t o r i n g . It s h o u l d be n o t e d t h a t t h i s i o n i z a t i o n m o d e g i v e s a p o o r r e s p o n s e f o r 2 , 3 , 7 , 8 - T C D D , b u t it r e s p o n d s well for all the other congeners (including other tetras).
831
832
Figure I. Map of Vietnam showing the Dong Nai River, Saigon River, and Red R i v e r about 1140 km from Hanoi to Ho Chi Minh City.
l!
is
833
Results and Discussion. The results of the study are shown in Table 1. An e x a m i n a t i o n of t h i s t a b l e s h o w s t h a t t h e c o n c e n t r a t i o n l e v e l s in a g i v e n s a m p l e d i f f e r d r a m a t i c a l l y f r o m one another but that the relative amounts of the various chloro-homologs w i t h i n a given sample are quite similar to one another. For example, all samples have OCDD as highest homolog but its concentration ranges from 210-4530 pg/g. T h e s e d a t a show t h e h i g h e s t c o n c e n t r a t i o n s in the Saigon R i v e r , m e d i u m c o n c e n t r a t i o n s in t h e D o n g N a i R i v e r , a n d t h e l o w e s t c o n c e n t r a t i o n s in the Red River. The overall p a t t e r n of P C D D / F chloro-homoiogs is one which might be related to c o m b u s t i o n p r o c e s s e s f o l l o w e d by a t m o s p h e r i c d e p o s i t i o n . T h e p a t t e r n of c h i o r o - h o m o l o g s is also similar to what was seen in the h u m a n f a t tissue from Vietnam previously reported (4).
TABLE 1 VIETNAM SEDIMENT CONCENTRATIONS IN PG/G DRY VEIGHT OF PCDD/F FROM RIVERS IN THE NORTH AND SOUTH OF VIETNAM, 1984/5
SAMPLE
TCDD PnCDD HxCDD HpCDD OCDD
Saigon R i v e r
--
87
220
Dang Nai R i v e r 1
-*
6.8
33
120
1200
Dang Nai R i v e r 2
--
4.2
11
68
750
11
Pang Rat R i v e r 3
--
6.7
17
140
1200
18
Dong Nai R i v e r 4
--
t.2
Dang Nai R i v e r 5
*-
0.9
Red R i v e r #1 Red R i v e r ~2
. . . . . . . .
8.2 13 0.5 0.9
940
TCDF
4530
PnCDF H x C D F
55 .
.
160 .
.
240 .
3.2 14
320
4.1 8.4
63
950
16
4.1
1120
11
4.0
25
0.4 0.4
---
240 210
2.6 1.8
230
.
160 10 5.1
NpCDF OCDF
2.8
2.2
3.1
2.9
21
2.1
3.3 48 1.0 0.4
12 4.1 51 0.9 0.8
TOTAL
6782 1365 858 1437 1052 1433 255 219
A BLANK INDICATES THAT THE ROMOLOG GROUP WAS NOT DETECTED AT A LIMIT OF DETECTION OF ABOUT 0.1 PG/G
TABLE 2 AVERAGE TOTAL CONCENTRATIONS OF PCDD/F |N PG/G FOR UPPERMOST LARE SEDIMENTSa AND VIETNAM RIVER SEDIMENTSb ~ietnem R i v e r s Sediments
Lake SedimenTs Site
Cone.
Site
Conc.
Lake Nuron
1240
Ssigo~
6800
Lake Michigan
1600
Dons Uai
1200
Lake E r i e
2150
Red R i v e r
Lake O n t a r i o S t s k t w l t Lake Lake Z u r i c h Lake | a L d e r s Lake L w s n o
11000 7"50 1500 1500 2000
a)
From J. M. Czuczve, Ph.D. Thesis (Reference I 1 0 )
b)
This s t u d y
240
834
In Table 2, the total average concentrations of P C D D / F are compared to the concentrations f r o m t h e u p p e r m o s t l a y e r of l a k e s e d i m e n t s p r e v i o u s l y r e p o r t e d (10). T h i s c o m p a r i s o n is not exact because river sediments reflect conditions upstream and lake sediments reflect conditions over most of the lake's watershed. E v e n so, it c a n be s e e n t h a t the S a i g o n R i v e r has c o n c e n t r a t i o n s o n l y e x c e e d e d b y L a k e O n t a r i o w h i c h is t h o u g h t to h a v e some direct c o n t a m i n a t i o n by P C D D / F f r o m p e n t a c h l o r o p h e n o l w a s t e s (10). T h u s , t h e S a i g o n R i v e r , in a h e a v i l y i n d u s t r i a l i z e d a r e a in w h i c h b o t h d i r e c t a n d i n d i r e c t c o n t a m i n a t i o n m i g h t be e x p e c t e d , has t h e h i g h e s t c o n c e n t r a t i o n a m o n g t h e V i e t n a m r i v e r s s t u d i e d . T h e n e x t h i g h e s t level of c o n c e n t r a t i o n is t h a t o f t h e D o n g N a i R i v e r . H e r e , the c o n c e n t r a t i o n s a r e s i m i l a r to lakes which are near industrial areas and receive considerable atmospheric input. As can be seen in Figure 1, the entire Dong Nai River is within 200 km of the industrialized area of Ho Chi Mirth C i t y , a n d t h u s , m i g h t be e x p e c t e d to r e c e i v e a t m o s p h e r i c d e p o s i t i o n o f P C D D / F . T h e lowest level o f c o n c e n t r a t i o n is t h a t seen in the Red R i v e r . T h i s level is e v e n less t h a n t h a t seen in the v e r y r e m o t e S i s k i w i t L a k e . A l t h o u g h t h i s is s o m e w h a t s u r p r i s i n g c o n s i d e r i n g the a r e a ' s p o p u l a t i o n (880,000), t h e s e low P C D D / F c o n c e n t r a t i o n s m i g h t be i n d i c a t i v e of conditions upstream. It s h o u l d be p o i n t e d o u t t h a t the H a n o i a r e a is not heavily industrialized and that the Hanoi area is where the lowest h u m a n adipose tissue levels of P C D D / F were seen. That TCDD was not f o u n d at any site, including Agent Orange sprayed areas, could have several explanations. F i r s t , s a m p l i n g s i t e s were g r a b s a m p l e s of the u p p e r m o s t s e d i m e n t , a n d TCDD c o n t a m i n a t e d material could have been buried by fresh sediment. It is also possible that the poor i n s t r u m e n t a l r e s p o n s e f o r 2 , 3 , 7 , 8 - T C D D in the n e g a t i v e i o n i z a t i o n m o d e p r e v e n t s its detection. To s u m m a r i z e , it h a s b e e n s h o w n t h a t r i v e r s e d i m e n t s in V i e t n a m a r e c o n t a m i n a t e d w i t h PCDD/F. T h e l e v e l s o f c o n t a m i n a t i o n f r o m the d i f f e r e n t a r e a s c o r r e l a t e w i t h the l e v e l s seen in h u m a n adipose tissue from the d i f f e r e n t areas. The levels are in the range previously seen f o r lake s e d i m e n t s a n d c a n p o s s i b l y be r e l a t e d to the a t m o s p h e r i c d e p o s i t i o n of P C D D / F produced by combustion sources. REFERENCES I. M. Nygren, C. Rappe, G. Lindstrom, M. Hanson, P. A. Berqvist, S. Marklund, L. Domellof, L. H a r d e l l a n d M. O i s s o n in Chlorinated Dioxins and Dibenzo/urans in Perspective (Eds. C. Rappe, G. C h o u d h a r y and L. Keith), Lewis Publishers, pp. 17-34 (1986). 2. A. J. S c h e c t e r , J. J. R y a n , M. Gross, N. C. A. W e e r a s i n g h e , a n d J. D. C o n s t a b l e Chlorinated Dioxins and Dibenzo/urans in Perspective (Eds. C. R a p p e , G. C h o u d h a r y a n d Keith), Lewis Publishers, pp. 35-50 (1986).
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