4 Disposition and Metabolism of Aromatic Hydrocarbons
Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on May 26, 2018 | https://pubs.acs.org Publication Date: May 24, 1979 | doi: 10.1021/bk-1979-0099.ch004
in Marine Organisms DONALD C. MALINS, TRACY K. COLLIER, and HERBERT R. SANBORN Environmental Conservation Division, Northwest and Alaska Fisheries Center, National Marine Fisheries Service, NOAA, 2725 Montlake Boulevard East, Seattle, WA 98112
In studies of the fate of hydrocarbons in terrestrial animals, considerable attention is directed toward relations between aromatic hydrocarbon metabolism, interactions of metabolites with macromolecules (e.g., DNA), and the formation of neoplastic lesions (1). A broad perspective exists in studies with marine organisms. In the aquatic forms, exposure to pollutants that are rich in aromatic hydrocarbons, such as petroleum, leads to a wide variety of acute and chronic effects (2). Attempts to delineate these effects require an understanding of the accumulation of the xenobiotics in tissues and an assessment of metabolite formation and retention. The important additional problem of the interaction of metabolites with genetic materials has not been studied to an appreciable degree in marine life. Reviews on the fate of aromatic hydrocarbons in marine organisms have been published (2,3,4). They indicated that a substantial amount of information exists on the accumulation of these compounds in a variety of phylogenetically diverse organisms. Recently, emphasis has shifted toward studies of bioconversions of these hydrocarbons. Work has been conducted on enzymes mediating the degradation of aromatic hydrocarbons and on the formation and retention of metabolites. Identifications of individual metabolites in tissues and body fluids of several marine organisms exposed to radiolabeled aromatic hydrocarbons have been made; however, insufficient information is available to determine the extent of differences in metabolite profiles as evinced from chromatographic data. In the present paper, emphasis will be placed on findings obtained in the last three years. Attention will focus on aromatic hydrocarbon accumulations and on the formation, retention, and structure of metabolites. Material appearing in recent reviews will not be emphasized (2,3,4). INCORPORATION OF HYDROCARBONS INTO TISSUES AND BODY FLUIDS Marine organisms readily accumulate aromatic hydrocarbons in This chapter not subject to U.S. copyright. Published 1979 American Chemical Society Khan et al.; Pesticide and Xenobiotic Metabolism in Aquatic Organisms ACS Symposium Series; American Chemical Society: Washington, DC, 1979.
PESTICIDE AND XENOBIOTIC M E T A B O L I S M IN AQUATIC
ORGANISMS
t i s s u e s when exposed through the d i e t , water column, or sediment (2,5,6). The extent of accumulation v a r i e s i n r e l a t i o n to such f a c t o r s as s p e c i e s , hydrocarbon s t r u c t u r e , route of a d m i n i s t r a t i o n , and environmental c o n d i t i o n s . Differences i n the tendency of organisms to accumulate aromatic hydrocarbons from the water column are i l l u s t r a t e d in Table I (7_). The data compare the uptake of s u b s t i t u t e d and nonsubstituted benzenes and naphthalenes i n t o muscle of coho salmon (Oncorhynchus kisutch) and s t a r r y flounder ( P l a t i c h t h y s s t e l l a t u s ) exposed under i d e n t i c a l c o n d i t i o n s to the w a t e r - s o l u b l e f r a c t i o n of Prudhoe Bay crude o i l . S t a r r y flounder muscle accumulated very high concentrations of the f o l l o w i n g aromatic hydrocarbons in comparison to coho salmon a f t e r two weeks of exposure: C3~substituted benzenes, C4/C5s u b s t i t u t e d benzenes, 2-methylnaphthalene, 1-methylnaphthalene, C 2 - s u b s t i t u t e d naphthalenes and C 3 - s u b s t i t u t e d naphthalenes. S t a r r y flounder tended to r e t a i n aromatic hydrocarbons f o r longer periods than coho salmon when both organisms were t r a n s f e r r e d to clean water. A f t e r two weeks i n clean water, the muscle of s t a r r y flounder contained 26 ppm of C4/C5~substituted benzene Table I
Hydrocarbons in muscle tissue of coho salmon (O. kisutch) and starry flounder (P.
exposed to the water-soluble fraction of Prudhoe Bay crude oil using flow-through exposure
stellatus) 3
Coho salmon Weeks of exposure
C.-Suhstituted benzenes C,-Substituted benzenes C -C,-Substituted benzenes Naphthalene 2-Methylnaphthalene l-Methylnaphthalene C-Substituted naphthalenes C,-Substituted naphthalenes 4
•α
II 10 150 20 30 30 30 50
0.31 0.30 1.5 0.07 0.10 0.10 0.31 0.23
SS' ± 0.12 ±0.61 ± 0.03 ± 0.05 ± 0.03 ± 0.30 ± 0.09
2.4 30 170 50 100 70 40 30
u
0.66 0.90 1.7 0.14 0.31 0.22 0.36 0.15
CQ i: a. SS ± 0.12 ± 0.50 ± 0.07 ± 0.01 ± 0.00 ± 0.00 ± 0.02
2 50 550 80 190 130 85 140
ή
0.55 1.5 5.5 0.24 0.56 0.40 0.90 0.70
SS ± 0.09 ±1.0 ± 0.06 ± 0.14 ± 0.08 ± 0.24 ± 0.22
I 10 200 40 70 50 40 80
h
îCL χί Week d. weeks ι
U
h
ba i:
6 Bioconcer t rat ion
Hydrocarbons
S
3
2
oconcer it ion >m dry .sue
Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on May 26, 2018 | https://pubs.acs.org Publication Date: May 24, 1979 | doi: 10.1021/bk-1979-0099.ch004
58
0. •=.
—£
0.27 0.40 2.0 0.12 0.20 0.16 0.44 0.40
NF NF NF NF NF NF NF NF
SS ±0.18 ±1.5 ± 0.06 ±0.10 ±0.08 ± 0.30 ± 0.40
Starry flounder Weeks of exposure 1 C.-Substituted benzenes C-Substituted benzenes Q-C-Substituted benzenes Naphthalene 2-Methylnaphthalene l-Methylnaphthalene C,.-Substituted naphthalenes C-Substituted naphthalenes
20 500 9300 700 2800 2000 2400 3400
5.5 ± 2 . 0 15 ± 5.7 93 ± 34 2.1 ± 1 . 5 8.3 ± 3.6 6.1 ± 4.3 24 ± 9.7 17 SS
Weeks of depuration
2
1 4 70 1700 240 470 330 540 1000
1.0 2.2 17 0.72 1.4 I.I 5.4 5.0
±0.30 ±1.2 ± 6.2 ± 0.30 ± 0.60 ± 0.50 ± 2.3 ± 2.0
I 6 980 100 110 113 270 420
0.27 0.18 9.8 0.30 0.33 0.34 2.7 2.1
± ± ± ± ± ± ± ±
0.06 0.03 0.40 0.02 0.03 0.01 0.80 0.00
10 2600 270 200 270 700 1600
2
0.30 26 0.80 0.60 0.82 7.0 8.0
NF ± 0.02 ± 1.6 ± 0.04 ± 0.02 ± 0.04 ±1.6 ±0.10
•' 0.9 ± 0.1 ppm (total hydrocarbons) in flow-through water. '' Bioconcentration = ppm hydrocarbon in dry weight tissue/ppm hydrocarbon in water ' Mean ± Standard error of mean for two 10- to 15-g composite samples each prepared from separate groups of coho salmon (2 fish/ group) '' Mean ± Standard error of mean for two 10- to 15-g composite samples each prepared from separate groups of starry flounder (5 fish/ group) ' SS = Single sample value N F = Not found: below limits of detection («0.05 ppm) 1
From Roubal et a l .
{]).
Khan et al.; Pesticide and Xenobiotic Metabolism in Aquatic Organisms ACS Symposium Series; American Chemical Society: Washington, DC, 1979.
Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on May 26, 2018 | https://pubs.acs.org Publication Date: May 24, 1979 | doi: 10.1021/bk-1979-0099.ch004
4.
MALINS E T AL.
Aromatic
59
Hydrocarbons
f r a c t i o n , and 7.0 and 8.0 ppm o f the C2- and C3~substituted naphthalenes, r e s p e c t i v e l y . Levels of petroleum hydrocarbons i n the g i l l s and l i v e r of s t a r r y flounder were g e n e r a l l y below l i m i t s of d e t e c t i o n . Hydrocarbons were not detected i n exposed salmon under comparable c o n d i t i o n s of d e p u r a t i o n . The strong tendency f o r coho salmon and s t a r r y flounder to accumulate a l k y l - s u b s t i t u t e d aromatic hydrocarbons through the water column i n preference to unsubstituted s t r u c t u r e s (Table I) suggests that hydrocarbon r e t e n t i o n increases i n proportion to the extent of r i n g s u b s t i t u t i o n i n these animals. Roubal et a l . (8J found that benzene, naphthalene, and anthracene administered i n the d i e t o f coho salmon accumulate i n t i s s u e s , such as l i v e r and muscle, i n proportion to the number of benzenoid rings i n the molecules. Thus, two s t r u c t u r a l properties—degree o f a l k y l a t i o n and number of fused rings—have been r e l a t e d to the d i s p o s i t i o n of aromatic hydrocarbons i n f i s h exposed through the d i e t and water column. These conclusions were not a p p l i c a b l e when sediment was the source o f hydrocarbons. McCain et a l . (5j studied the b i o a v a i l a b i l i t y of petroleum i n sediment to E n g l i s h s o l e (Parophrys v e t u lus). Sediments r i c h i n a l k y l a t e d and n o n - a l k y l a t e d benzenes and naphthalenes, together with fluorene and phenanthrene, were employed. A f t e r 11 days of exposure, samples of s k i n , muscle, and l i v e r were examined. Fluorene and phenanthrene were not accumulated i n the t e s t f i s h ; however, s i g n i f i c a n t concentrations of 1-methylnaphthalene, 2-methylnaphthalene, 2,6-dimethylnaphtha lene and 1,2,3,4-tetramethylbenzene, were found i n s k i n and l i v e r (Table I I ) ; 1-methylnaphthalene and 2-methylnaphthalene were the major components o f muscle. In each t i s s u e examined, 1-methylnaphthalene was the major component; 1,2,3,4-tetramethylbenzene occurred i n r e l a t i v e l y low concentrations i n skin and muscle i n comparison to naphthalenes containing one and two a l k y l groups. TABLE I · Petroleum hydrocarbons in the tissues of English sole exposed to oil-contaminated sediment (test, T) and to nonoiled sedimtm (control, C) for 2 mo continuously. Concn (ng/gm dry wt)
Polycyclic aromatic hydrocarbons* 1,2,3,4-tetramethylbenzene Biphenyl Naphthalene 1 -methylnaphthalene 2-methylnaphthalene 2,6-dimethylnaphthalene
Skin C — — — — — —
Muscle C
Τ 33 156 82 1189 888 130
b
51 d
27 d
11 d
Τ
—
44
— — —
20 369 279
Liver C — — — — —
Τ 922 307 100 1940 3070
Skin c
Τ
- -
muscle c
Τ
—
Liver C
Τ
— —
863 278
— —
1325 1500
Skin C
Τ
Muscle C
—
Τ
Liver C
Τ
—
124
—
60
Arenes with aromatic rings ranging from one to six, i.e. o-xylene to benz[«]anthracene, were determined and only the com pounds listed here were found in significantly higher concentrations in test fish. Skin and liver samples were pooled from three fish at each analysis; muscle samples were analyzed individually. a
b
From McCain et a l .
(5).
Khan et al.; Pesticide and Xenobiotic Metabolism in Aquatic Organisms ACS Symposium Series; American Chemical Society: Washington, DC, 1979.
Downloaded by UNIV OF CALIFORNIA SANTA BARBARA on May 26, 2018 | https://pubs.acs.org Publication Date: May 24, 1979 | doi: 10.1021/bk-1979-0099.ch004
60
PESTICIDE AND XENOBIOTIC M E T A B O L I S M IN AQUATIC ORGANISMS
These data imply that aromatic hydrocarbons incorporated i n t o sediments are not p r e f e r e n t i a l l y accumulated in r e l a t i o n to increased a l k y l s u b s t i t u t i o n , as shown with d i e t a r y and seawater exposures. Moreover, the apparent lack of accumulation of the fluorene and phenanthrene suggests that unsubstituted aromatic hydrocarbons having more than two benzenoid r i n g s may not be r e a d i l y sequestered by f i s h exposed to petroleum-impregnated sediment. These d i f f e r e n c e s are presumably r e l a t e d , at l e a s t i n p a r t , to physico-chemical i n t e r a c t i o n s of aromatic hydrocarbons with sediment matrices that regulate t h e i r b i o a v a i l a b i l i t y . Melancon and Lech (9) ( F i g . 1) found with rainbow t r o u t (Salmo g a i r d n e r i ) that d i f f e r e n c e s e x i s t e d i n the accumulation and e x c r e t i o n of r a d i o l a b e l e d naphthalene and 2-methylnaphthalene, i n c l u d i n g p o s s i b l e bioconversion p r o d u c t s , in exposures through the water column. The a l k y l a t e d naphthalene was taken up more r a p i d l y than the unsubstituted naphthalene. Moreover, i t was i n i t i a l l y accumulated to higher l e v e l s in a l l t i s s u e s studied and eliminated more r a p i d l y from muscle, l i v e r , and b l o o d . These workers suggest that exposure of t r o u t to naphthalene over extended periods may lead to higher concentrations in t i s s u e s of parent compounds and metabolites than would occur with 2-methylnaphthalene. A c c o r d i n g l y , exposure time i s important in assessing the r e t e n t i o n of aromatic hydrocarbons and t h e i r bioconversion products in marine organisms. Evidence p e r t a i n i n g to the i n f l u e n c e of compounds such as PCBs and heavy metals on aromatic hydrocarbon accumulations i n marine organisms were discussed in recent review papers ( 3 , 4 ) . The i n f l u e n c e of such compounds on metabolizing enzyme systems and e x c r e t i o n processes appears to be s i g n i f i c a n t i n some cases so that the d i s p o s i t i o n o f hydrocarbons i s l i k e l y to be a f f e c t e d . Environmental temperature i n f l u e n c e s the degree of hydrocarbon accumulation in marine f i s h . C o l l i e r et a l . (10) found that depressed temperature ( 4 ° v s . 10°C) r e s u l t e d in s i g n i f i c a n t l y (P
