H E L G O ~ D E R MEERESUNTt~.RSUCHUNGEN
Helgol&uder Meeresunters. 33, 301-312 {1980)
Effects of pesticides and related organic c o m p o u n d s
in the sea
W. Ernst
Institut fiir Meeresforschung Bremerhaven;
A m Handelshafen 12, D-2850 Bremerhaven, Federal Republic of Germany
ABSTRACT: The majority of organic chemicals identified so far in the sea are pesticides and
products of technical use; most contain chlorine. Only a limited amount of the actual pollutant load
is detectable because few data for "unconventional" pollutants are available. In view of the
considerable structural variety of the large number of chemicals produced, there is a need for
prediction measurements of bioconcentrafion and toxic effects. Physico-chemical data may be used
for predicting bioconcentration and life-cycle toxicity tests for the estimation of safe levels. The
degree of biomagnification via food chains increases with half lives of the pollutants. When
comparing pollutant concentrations with toxicological data it becomes apparent that estuaries and
coastal areas deserve special concern, whereas pollutant levels of open ocean waters are unlikely to
endanger marine life at present.
INTRODUCTION
O r g a n i c c h e m i c a l s of a n t h r o p o g e n i c origin are an i n c r e a s i n g threat to the m a r i n e
e n v i r o n m e n t . M o r e t h a n 60 000 c o m m o n c h e m i c a l s are in u se a n d some h u n d r e d n e w
c h e m i c a l s p e r y e a r w i l l b e added. Obviously, m a n y of t h e m will r e a c h estuaries,
coastlines a n d e v e n the o p e n sea v i a w e l l - k n o w n routes such as rivers, a t m o s p h e r i c
transport or d u m p i n g . S o m e of t h e s e c h e m i c a l s e x h i b i t c o n s i d e r a b l e p e r s i s t e n c e in the
e n v i r o n m e n t a n d are p r o d u c e d in l a r g e q u a n t i t i e s on a scale of up to a m i l l i o n tons p er
year, so that t h e y h a v e n o w b e c o m e d e t e c t a b l e c o m p o u n d s in sea water, s e d i m e n t s an d
biota. It is, on th e o t h e r hand, t h e sensitivity a n d specificity of a n a l y t i c a l m e t h o d s that
g o v e r n s the d e g r e e of r e c o g n i t i o n ol t h e p r e s e n t p o l l u t a n t load in the sea. M a n y
c o m p o u n d s in t h e s e a are still u n k n o w n , b u t t h e y m a y occur at c o m p a r a t i v e l y h i g h
concentrationsl others, that will s h o w up by i m p r o v e d a n a l y t i c a l t e c h n i q u e s , m a y b e of
n e g l i g i b l e significance.
It w o u l d go b e y o n d the scope ol this p a p e r to g i v e a c o m p l e t e r e v i e w of the vast field
of i n t e r r e l a t i o n s b e t w e e n o r g a n i c pollutants an d l i v i n g an d d e a d m a t t e r in t h e sea. I
c o n s i d e r h e r e the f o l l o w i n g questions: (a) W h i c h o r g an i c s u b s t a n c e s do actually a n d
p r e f e r a b l y occur in the sea a n d w h a t are t h e ir concentrations? (b) W h a t is their p r i n c i p a l
fate? {c) W h a t are t h e effects that can b e o b s e r v e d or e x p e c t e d ? (d) H o w can the results b e
u s e d in a risk a s s e s s m e n t for t h e s e c h e m i c a l s ?
T h e q u e s t i o n of risk a s s e s s m e n t has b e e n e m p h a s i z e d : p r o b a b l y the h i g h p r o d u c t i o n
of o r g a n i c c h e m i c a l s w i l l c o n t i n u e a n d n e w c o m p o u n d s will substitute those w h o s e
9 Biologische Anstalt Helgoland
0017-9957/80/0033/0301/$ 02.00
302
W. Ernst
e n v i r o n m e n t a l b e h a v i o u r is already w e l l k n o w n . It is therefore n e c e s s a r y to d e v e l o p
reliable laboratory methods for predicting relationships b e t w e e n the e n v i r o n m e n t a l
effects and substance parameters. This w i l l perhaps e n a b l e us to m a k e more appropriate
appraisals before a n e w substance is released.
SUBSTANCES A N D THEIR C O N C E N T R A T I O N S
Organic substances identified so far in the sea comprise: (1) pesticides and their
metabolites; (2) products of technical use and their by-products. Figure 1 shows the
concentrations of various c o m p o u n d s in the surface water of near-shore waters and the
o p e n sea. Pollutant concentrations from both areas are compared to demonstrate the
h i g h e r pollution of estuaries and coastal waters and the dilution effects. Levels in the
o p e n sea do not e x c e e d a v a l u e of 10 n g 1-1. Exceptions are the phthalate esters
dibutylphthalate (DBP) and d i - 2 - e t h y l h e x y l p h t h a l a t e (DEHP), w h i c h s h o w comparatively h i g h concentrations in the Gulf of Mexico but DBP could not be detected in the
northern Atlantic (Giam et al., 1978}. Other c h e m i c a l s in Figure 1 , such as pentachlorophenol (PCP), can be detected in the German Bight at low concentrations but m a y
be u n d e t e c t a b l e in o c e a n waters (Weber & Ernst, 1978}; y - h e x a c h l o r o c y c l o h e x a n e (yHCH) and its isomer a-HCH m a y b e h a v e correspondingly.
Estuary, Coast
Open Sea
DBP
1000-
DSs - - ' ~
DEHP
i
--Perchlorethylene
PCP
Tetrachlorophenol
100-
/~
9
Trichlorethylene - -
~-HCH
a-HCH
10-
Trichlorophenol
a -HCH
r/--Hexachlorobutadiene
y - HC H
PCP
PCB
PCB
9
Trichloro fluoromethane
Perchlorethylene
Dieldrin
DDT
Carbontetrachloride
9
9
Te trach loropheno i
9
Trichlorophenol
DEHP
--Trichlorethylene
Carbontetracn•
1,1,1-Trichlorethane
1-
~k
DDT
Dieldrin
9
0,1-
9 0,01-
Fig. 1. Concentration of various organic substances in sea water of the open sea, estuaries and
coastal areas {after Murray & Riley, 1973; Pearson & McConnell, 1975; Stadler, 1977; Ernst & Weber,
1978; Giam et al., 1978; Weber & Ernst, 1978}
Effects of p e s t i c i d e s
303
It s h o u l d b e n o t e d that v a l u e s in F i g u r e 1 w e r e o b t a i n e d in surface w a t e r s b u t
c o n c e n t r a t i o n s d e c l i n e w i t h i n c r e a s i n g d e p t h . V a l u e s p r e s e n t e d for e s t u a r i e s a n d coastal
w a t e r s are c o n s i d e r a b l y h i g h e r ; t h e y v a r y w i t h t i d a l fluxes a n d e m i s s i o n rates. Polyc h l o r i n a t e d b i p h e n y l s are u s u a l l y d e t e r m i n e d g a s c h r o m a t o g r a p h i c a l l y v i a p a t t e r n
r e c o g n i t i o n u s i n g PCB-types such as Aroclor 1254 or C l o p h e n A 60. M o r e p r e c i s e
e v a l u a t i o n can b e e x p e c t e d w i t h g l a s s - c a p i l l a r y g a s c h r o m a t o g r a p h y , w h i c h m o r e
effectively s e p a r a t e s i n d i v i d u a l c o m p o u n d s . More t h a n 80 different c h l o r o b i p h e n y l s
r a n g i n g from trichloro- to o c t a c h l o r o b i p h e n y l s (Zell et al., 1978) w e r e d e t e c t e d in livers
of fish from t h e North S e a u s i n g this m e t h o d . H e x a c h l o r o b e n z e n e , not l i s t e d in F i g u r e 1,
is a further p o l l u t a n t in the m a r i n e e n v i r o n m e n t a n d a l t h o u g h its d e t e c t i o n in m a r i n e
a n i m a l s d e m o n s t r a t e s its p r e s e n c e in s e a water, no q u a n t i t a t i v e d a t a are r e p o r t e d for s e a
water. It s e e m s that at p r e s e n t o n l y a m i n o r p a r t of the a c t u a l l o a d of o r g a n i c p o l l u t a n t s is
w e l l known. G r o u p p a r a m e t e r s such as o r g a n i c a l l y b o u n d chlorine illustrate that for
e x a m p l e , s e a w a t e r from t h e Oslo F j o r d c o n t a i n e d 40-195 n g 1-1 of o r g a n i c chlorine b u t
only 1-2 n g 1-1 c o u l d b e a s s i g n e d to PCB as the most p r o m i n e n t c o m p o u n d ; s i m i l a r
f i n d i n g s w e r e m a d e w i t h o r g a n i c a l l y b o u n d chlorine in fish oils (Lunde & Steinness,
1975; L u n d e et al., 1975). A l o a d of m o r e t h a n 104 t o n s / y e a r o r g a n i c a l l y b o u n d chlorine
a s l i p o p h i l i c o r g a n i c c h l o r i n e c o m p o u n d s a n d 300 t o n s / y e a r c h o l i n e s t e r a s e inhibitors as
p a r a t h i o n e q u i v a l e n t s are d i s c h a r g e d b y the River Rhine; 90 % of t h e s e c o m p o u n d s will
e s c a p e g a s c h r o m a t o g r a p h i c d e t e c t i o n (Poels et al., 1978). C u r r e n t a n a l y t i c a l w o r k in our
l a b o r a t o r y i n d i c a t e s that a n u m b e r of c o m p o u n d s p r e v i o u s l y u n k n o w n as m a r i n e pollutants c a n b e d e t e c t e d in N o r t h S e a w a t e r after a p p r o p r i a t e solvent e x t r a c t i o n a n d u s i n g
a n a l y t i c a l t e c h n i q u e s such as c o m p u t e r i z e d g a s c h r o m a t o g r a p h y c o m b i n e d w i t h m a s s
spectrometry. The c o m p o u n d s i n c l u d e c h l o r i n a t e d aromatics, o r g a n o p h o s p h o r o u s comp o u n d s a n d P A H ' s (Weber, in p r e p a r a t i o n ) .
BIOCONCENTRATION AND BIOMAGNIFICATION
Historically, studies on the o r g a n o h a l o g e n c o m p o u n d s a n d e s p e c i a l l y DDT l e d to
i n t e n s i v e r e s e a r c h on b i o c o n c e n t r a t i o n p h e n o m e n a in a q u a t i c e n v i r o n m e n t s . M a n y d a t a
h a v e b e e n o b t a i n e d b u t few are d i r e c t l y c o m p a r a b l e b e c a u s e of m e t h o d i c a l variations,
e.g. differences in species, m a i n t e n a n c e of organisms, s u b s t a n c e concentrations, t e m p e r ature, salinity, s u b s t r a t e carriers, k i n e t i c variations. N e v e r t h e l e s s , some d e t a i l s d e r i v e d
from t h e s e i n v e s t i g a t i o n s "may c o n t r i b u t e to the q u a n t i t a t i v e d e s c r i p t i o n of the p r o c e s s e s
of u p t a k e a n d r e l e a s e of c h e m i c a l s in organisms. Bioconcentration occurs d i r e c t l y b y
u p t a k e from w a t e r or i n d i r e c t l y v i a food chains. Most w o r k h a s b e e n d o n e on the former.
B i o c o n c e n t r a t i o n p o t e n t i a l s for o r g a n i c p o l l u t a n t s m a y b e d e s c r i b e d b y the c o n c e n t r a t i o n
factor (CF), the ratio of the c o n c e n t r a t i o n in a n i m a l s to that in water. It is n o w
i n c r e a s i n g l y a c k n o w l e d g e d that b i o c o n c e n t r a t i o n factors s h o u l d b e d e t e r m i n e d at
s t e a d y - s t a t e conditions in o r d e r to o b t a i n c a l c u l a b l e data.
In v i e w of the m a n y o r g a n i c s u b s t a n c e s that are p o t e n t i a l e n v i r o n m e n t a l pollutants,
it is not s u r p r i s i n g that a m a j o r o b j e c t i v e in this field has b e e n t h e collection of b a s i c d a t a
for predictions. A m o n g the p h y s i c o - c h e m i c a l p a r a m e t e r s r e c e n t l y i n t r o d u c e d for this
p u r p o s e , the most p r o m i s i n g are w a t e r s o l u b i l i t y a n d p a r t i t i o n coefficients. A correlation
of b i o c o n c e n t r a t i o n factors w i t h w a t e r s o l u b i l i t y is p r e s e n t e d in F i g u r e 2. A l l v a l u e s
m e a s u r e d are o b t a i n e d at s t e a d y state from e x p e r i m e n t s w i t h b i v a l v e s a n d fish. The
304
W. Ernst
"..~:
...-.
9. - . k e / - -
2,4,5,2 ' , 4 ' , 5 ' - H e x a c h l o r o b i p h e n y l
~ / ~ / / DDE
DDD
DDT
HCB
(3)
(6)
(7) ~
(8)
Aldrin
3
..
D'q.....
(4)
2,5,2' , 5' - T e t r a c h l o r o b i p h e n y l
(9)
-....'..'",..~,.
-.
Endrin
(15) . J
e -Endosulfan
(21)
(10)
(I 4)
E n d r i n (18)
E n d r i n (13)
Heptachlorepoxide
9 ..
--I~k'~
Methoxychlor
(5)
2,5,2',5'-Tetrachlorobiphenyl
9 2,5,2'-Trichlorobiphenyl
"'..?...
(12)
(16)
(17)
(2)
2 , 4 , 5 , 2 ' , 5 '- P e n t a c h l o r o b i p h e n y l
"::::..~/
(11 ) - - ,
Dieldrin
Dieldrin
Dieldrin
(I)
2,3,4,2',5'-Pentachlorobiphenyl
"'~""...
'. "..
9 "..9. "%".
"..
Endrin
"..
e--
(19)
(28)
PCP
(22)
"""..
.""'-..%
Molluscs/''
o
o
a - HCH
2
(29) - e
~- ~cH (24)
O"'.
7 - ~ca (23)
,
Tetrachlorethylene
Carbontetrachlor
I
0
I
1
I
2
I
3
Fish
""......."..................
"-........~o.,....
.../.
".
"..
.......
/
(26)-ide
/B
(27)
I
4
log solubility ( pg- 1-1 )
"
I
5
%"""..
I
6
Fig. 2. Correlation between water solubility and bioconcentration factors of organic substances in
fish and bivalves. Number refer to substances: No. 1, 2, 9 (Vreeland, 1974); No. 3, 4, 5, 10 (Metcalf et
al., 1975)~ No. 6, 13, 17, 19, 21, 24, 29 (Ernst, 1977); No. 7, 11, 15, 16, 23, 28 (Butler, 1971); No. 8, 14,
26, 27 (Neely et al., 1974); No. 12, 18 (Mason & Rowe, 1976); No. 22 (Ernst, 1979)
correlation reveals that the bioconcentration potential increases w i t h d e c r e a s i n g solubility. At present such a relationship must be regarded as hypothetical b e c a u s e determinations of solubilities as l o w as indicated are difficult and contradictory results are reported
in the literature (Gunther et al., 1968; W e i l et al., 1974; H a q u e & S c h m e d d i n g , 1975;
Chiou et al., 1977).
The u s e of partition coefficients for these correlations appears to be more conspicuous b e c a u s e the distribution of a c h e m i c a l in an organism can be regarded as a partition
process operating b e t w e e n the a q u e o u s phase and the organic compartment. Partition
coefficients for this purpose refer to the n-octanol-water system. Experimentally, they
can more easily be obtained than solubility data and are furthermore calculable from
c h e m i c a l structures v i a fragment constants (Leo, 1975). A correlation of these data with
bioconcentration factors has b e e n s h o w n for fish according to the e q u a t i o n log (bioconc.
factor) = 0.542 log (partition coeff.) + 0.124 ( N e e l y et al., 1974). A similar correlation for
b i v a l v e s is exhibited in Figure 3 u s i n g partition coefficients from various authors ( N e e l y
et al., 1974; Leo, 1975; C h i o u et al., 1977). It should be noted again that the logarithms of
Hffects of p e s t i c i d e s
305
2,4,5,2 ' , 4 ' , 5 ' - Hexachlorobiphenyl
(I )
I9
....""
......
......."
.....
9 ...... 9 ........
9
(6)
4
.....
~
~3
....
E
\~
~
D
........
:%
2
.........
........
~
9"
~
~-HCH
(24)
7-HCH
(23)
(7)
3,4,2 -Trichlorobiphenyl
(20)
Dieldrin (I 2)
Endrin (18)
Endrin (13)
Dieldrin (17)
\\%
...........
o
o
, DDT
......
~
a-HCH (29]
I
I
I
I
4
5
6
7
log
partition
coefficient
Fig. 3. Correlation b e t w e e n partition coefficients and bioconcentration factors of organic substances
in bivalves. Number refer to substances: No. 1, 20 (Vreeland, 1974); No. 6, 13, 17, 24, 29 (Ernst,
197Y); No. 7, 23 (Butler, 19Yl); No. 12, 18 (Mason & Rowe, 1976)
j#
iI
15
jl
13
IJj
iI
iJ j
iI I
jI
iIP
jII
/
70
It
pll II
o
E
~5
5
/./
//"
/
/./
//
/
/////"
110
20
30
,/
/"
/"
.......................
40
50
0
70
Z
80
Half life (days)
Fig. 4. Correlation b e t w e e n elimination half lives and biomagnification in two consumer levels. I, II:
calculated curves for a feeding rate of 3 % of body weight. Biomagnification factor 1 = 100 %
additional uptake of substance via food in relation to uptake from water
306
W. Ernst
v a r i a b l e s are p l o t t e d a n d therefore these figures s h o u l d b e u s e d w i t h s o m e care, b u t it
s e e m s f e a s i b l e to d e r i v e p r e l i m i n a r y information on b i o c o n c e n t r a t i o n p r e d i c t i o n from
w o r k of this type.
F o o d - c h a i n transfer of o r g a n i c p o l l u t a n t s s h o u l d not b e n e g l e c t e d in the overall
a c c u m u l a t i o n processes. A l t h o u g h sufficient results are a v a i l a b l e on the s i g n i f i c a n c e of
s u b s t a n c e a c c u m u l a t i o n v i a food, no c l e a r - c u t c o n c e p t i o n c a n so far b e o b t a i n e d a m o n g
the controversial s u g g e s t i o n s a n d results.
In o r d e r to e s t i m a t e the s h a r e of b i o m a g n i f i c a t i o n , a m o d e l h a s b e e n d e v e l o p e d
u s i n g half lives or e l i m i n a t i o n constants (Ernst, in preparation). In F i g u r e 4 b i o m a g n i f i cation factors from this m o d e l are p l o t t e d versus half lives for two s u b s e q u e n t c o n s u m e r
levels. A l t h o u g h the m o d e l m a y b e a d a p t e d to v a r y i n g p a r a m e t e r s , t h e f o l l o w i n g
a s s u m p t i o n s h a v e b e e n m a d e : (a) the c o n c e n t r a t i o n of the s u b s t a n c e in w a t e r is constant;
(b) C o n s u m e r II f e e d s e x c l u s i v e l y on C o n s u m e r I at a constant d a i l y rate; (c) the p o l l u t a n t
p r e s e n t in C o n s u m e r I is q u a n t i t a t i v e l y a b s o r b e d b y C o n s u m e r II; (d) the b i o c o n c e n t r a tion factors from w a t e r a n d the e l i m i n a t i o n rate constants are the s a m e for the c o n s u m e r s
a n d the p r o c e s s e s are in e q u i l i b r i u m ; (e) d e g r a d a t i o n of the s u b s t a n c e does not occur a n d
r e l e v a n t p h y s i o l o g i c a l differences b e t w e e n the c o n s u m e r s do not exist. A l t h o u g h the
b i o m a g n i f i c a t i o n factors in F i g u r e 4 are over-simplified, some l i m i t i n g e s t i m a t e s can b e
m a d e . F i g u r e 4 shows that s u b s t a n c e s e x h i b i t i n g half lives of a b o u t 10-20 d a y s will at
most l e a d to l e v e l s twice as h i g h as those o b t a i n e d v i a b i o c o n c e n t r a t i o n from water. A
s u b s t a n t i a l i n c r e a s e of one o r d e r of m a g n i t u d e will occur only at h i g h half lives b u t
h a r d l y at C o n s u m e r l e v e l I. It s h o u l d b e n o t e d that, in contrast to t h e p r o c e s s of u p t a k e
from water, m o r e t i m e is n e e d e d b e f o r e t h e b i o m a g n i f i c a t i o n b e c o m e s a p p a r e n t a n d 4 to
5 half lives are r e q u i r e d to a t t a i n m o r e t h a n 90 % of the t h e o r e t i c a l value.
METABOLISM
The structure of o r g a n i c m o l e c u l e s m a y b e f u n d a m e n t a l l y m o d i f i e d in l i v i n g organisms. G e n e r a l l y this results in the p r o d u c t i o n of less h a r m f u l substances, b u t it is p o s s i b l e
for m e t a b o l i t e s to e x h i b i t p r o p e r t i e s m o r e d e t r i m e n t a l t h a n those of the p a r e n t comp o u n d s , e. g. h i g h e r d e g r e e s of p e r s i s t e n c e or e l e v a t e d toxicity. In v i e w of these
i m p o r t a n t facts, s u r p r i s i n g l y little w o r k h a s b e e n d o n e on m e t a b o l i c studies in a q u a t i c
s p e c i e s c o m p a r e d w i t h terrestrial species. This m a y b e d u e to difficulties such as h i g h
toxicity a n d low transformation rates for most o r g a n i c c o m p o u n d s . Brodie & M a i k e l
(1962) s u g g e s t e d that fish, for e x a m p l e , is l a c k i n g in the a b i l i t y to m e t a b o l i z e foreign
c o m p o u n d s , b u t more r e c e n t f i n d i n g s d e m o n s t r a t e that m a r i n e s p e c i e s do i n d e e d h a v e a
m i x e d function o x i d a s e s y s t e m l o c a t e d in t h e m i c r o s o m e s w h i c h is r e s p o n s i b l e for the
o x i d a t i o n of o r g a n i c c o m p o u n d s (Pohl et al., 1974).
Some p a t h w a y s of m e t a b o l i c transformations are s h o w n in F i g u r e 5 for different
species. P e n t a c h l o r o p h e n o l c a n e a s i l y b e c o n j u g a t e d w i t h s u l p h u r i c a c i d in b i v a l v e s
(Kobayashi et al., 1970; Ernst, 1979) or w i t h g l u c u r o n i c a c i d in fish ( G l i c k m a n et al.,
1977). The c h l o r o b i p h e n y l s are u s u a l l y stable, e s p e c i a l l y the h i g h e r c h l o r i n a t e d ones,
b u t a s u b s t a n t i a l h y d r o x y l a t i o n was o b s e r v e d in the m a r i n e p o l y c h a e t e N e r e i s virens
(Ernst et al., 1977) a n d a m e t h y l s u l p h o n e m e t a b o l i t e w a s d i s c o v e r e d in seals (Jensen &
Jansson, 1976). DDE a n d DDD are w e l l k n o w n m e t a b o l i t e s of DDT; F i g u r e 5 shows a
h y d r o x y l a t i o n p r o d u c t of DDE i s o l a t e d from f a e c e s of seals (Sundstr6m et al., 1975) a n d a
Effects of pesticides
307
methylsulphone metabolite of DDE derived from seal blubber (Jensen & Jansson, 1976).
Phthalate esters, such as di-2-ethylhexyl-phthalate, may be transformed to mono-esters
and phthalic acid (Stalling et al., 1973).
The metabolites shown in Figure 5 are more polar than the parent compounds. When
w e go back very briefly to the difficulties in the analysis of pollutants, w e can easily
conclude that these compounds will remain undetected in the usual analytical systems
arranged for non-polar compounds. The initial metabolic modification of the m o l e c u l e
will probably facilitate the subsequent total break down. On the other hand, it should not
be overlooked that a reaction like the conjugation of phenols does not alter the structure
of the compound; in this case, the free phenol will be available w h e n the conjugate is
hydrolyzed.
OH
Cb'~~CI
y
A
Clx
Cly
sea,
O=S=O
i
OH3
Cl CI
CI
B
CI
b,valves
CI-~O-S03H
OH
CI
Cl
Cl
CI CI
f~sh'~'~,,
CI Cl
COOH
CI@O-~ H
CI CI
c c,
H
c
OH H
c, c9
c,
OH
CI CI
c,-~c-~c,
~c~C~, ~'~
O=S=O
i
CHa
C2H5
~ T cOO-CH2-CH-(cH2)a-cH3
C2H5
D
~------~CO0-CH~-CH-(CH2)3-CH3 ~
~CO0_CH
_CH_(CH2)3_CH 3
C2H5
f~
~COOH
F , ~ C O 0 H/
conjugated
products
~COOH
Fig. 5. Metabolic degradation of organic substances in aquatic animals. A: Polychlorinated
biphenyls, B: pentachlorophenol, C: DDT, D: di-2-ethylhexylphthalate
W. Ernst
308
TOXICITY
The occurrence of o r g a n i c c h e m i c a l s in the m a r i n e e n v i r o n m e n t r e q u i r e s e v a l u a t i o n
of the effects that t h e y m a y h a v e d i r e c t l y on a s p e c i e s or i n d i r e c t l y on the m a r i n e
ecosystem. In a q u a t i c toxicology, t h e a c u t e toxicity test for i n v e r t e b r a t e s a n d fish e n a b l e s
e s t i m a t i o n of the e x p o s u r e c o n c e n t r a t i o n r e s u l t i n g in 50 % m o r t a l i t y of the test a n i m a l s
w i t h i n 48 or 96 h; it is e x p r e s s e d as LCs0. T h e n u m e r i c a l v a l u e of t h e LCs0 has a s s u m e d
s p e c i a l i m p o r t a n c e as a n i n d e x of toxicity, b u t w i t h the i n c o r p o r a t i o n of h i g h l y p e r s i s t e n t
s u b s t a n c e s w i t h h i g h b i o c o n c e n t r a t i o n p o t e n t i a l s a n d low w a t e r s o l u b i l i t i e s it c a n
p r o v i d e only m a r g i n a l information. T o x i c o l o g i c a l l y it is i n a d e q u a t e a n d m a n y b i o l o g i c a l
effects of p o l l u t a n t s m a y not b e evident. W h e n t e s t i n g a c c u m u l a t i n g substances, t h e LCso
m a y d e c r e a s e c o n s i d e r a b l y w i t h i n c r e a s i n g e x p o s u r e p e r i o d s (Eisler, 1970; H o l d e n ,
1973); n e i t h e r this, nor t h e p o s s i b i l i t y that the test c o m p o u n d s m a y e v a p o r a t e or b e
a d s o r b e d to the w a l l s of the t a n k s in static tests, w a s sufficiently c o n s i d e r e d in e a r l y
e x p e r i m e n t s . But t h e r e a r e m a n y other factors affecting the LCs0 v a l u e s of o r g a n i c
Carbontetrachloride
IH
Trichlorethane
IH
Trichlorethylene
IH
Perchlorethylene
IH
Hexachlorobutadiene
IH
Dibutylphthalate
I
IF
IA
Malathion
PCB(Aroclor 1254)
iE
Pentachlorophenol
I
-HCH
~ D
I
Kepone
I
IA
IC
I
Heptachlor
IA
HA
F.-4A
Dieldrin
Aldrin
Endosulfan
tG
I
Methylparathion
a
IB
I
Endrin
IA
HA
Methoxychlor
1
DDT
0,1
IA
1
10
100
103
104
105
LCso (#g-1-1 )
Fig. 6. Acute toxicity of pesticides and other organic substances in fish. Values for PCB: pink shrimp
and crayfish. A: Holden (1973); B: Schimmel et al. (1977); C: Schimmel & Wilson (1977); D:
Schimmel et al. (1978)7 H: Stalling & Mayer (1972); F: Eisler (1970 b G: Peakall (1975 b H: Pearson &
McConnell (1975)
Effects of pesticides
Trichlorethylene
Perchlorethylene
Dibutylphthalate
_
m
m
--
PCB
(Aroclor
309
[]
1254)
Pentachlorophenol
m
--
m
7-HCH
D
Dieldrin
m
m
DDT
I
0.01
I
I
I
I
I
I
I
I
I
I
0.1
1
10
100
103
104
105
10 e
107
10 s
Concentration (ng. I-~)
Fig. 7. Concentration of organic pollutants in water in comparison to toxic concentrations. Concentrations in water and LCs0 values are from Figures 1 and 6. Hatched bars: pollutant concentrations
in sea water; black bars: toxic concentrations; toxicity data from more sensitive criteria: PCB
(Aroclor 1254) (Schimmel et al., 1974); pentachlorophenol (Tagatz et al., 1977)
chemicals to fish, e. g. species relationships, temperature, salinity, o x y g e n concentration, d e v e l o p m e n t a l stage, physiological condition, time of exposure, as well as experim e n t a l conditions such as c o n t i n u o u s flow or static exposure. For a n u m b e r of organic
c o m p o u n d s i n c l u d i n g pesticides a n d t e c h n i c a l products, the LC50 v a l u e s o b t a i n e d for
fish b y various authors are c o m p i l e d i n Figure 6. With a few exceptions, v a l u e s were
selected for m a r i n e species over a 48-h or 96-h period.
The acute toxicity data have often b e e n u s e d i n c o n j u n c t i o n with so-called safety
factors of 0.1 to 0.01 to estimate safe concentrations of chemicals for the protection of
a q u a t i c life d u r i n g chronic exposure. However, these factors do not a d e q u a t e l y consider
the specific toxic actions of the i n d i v i d u a l substances. More t h a n 10 years ago the
concept of specific a p p l i c a t i o n factors was introduced. This defines the r e l a t i o n s h i p
b e t w e e n the acute a n d chronic toxicity of a chemical; the accurate estimate of the
specific a p p l i c a t i o n factor for a c h e m i c a l c a n b e d e r i v e d from m a x i m u m a c c e p t a b l e
toxicant concentrations (MATC). The M A T C c a n b e d e t e r m i n e d i n chronic exposure
tests i n c l u d i n g the most sensitive life stages, i. e. embryos a n d n e w l y h a t c h e d fry, or i n
tests w h e r e a n i m a l s are exposed to the chemical over their entire life cycle. Numerically,
the a p p l i c a t i o n factor AF is the q u o t i e n t of the M A T C a n d the 96-h LC50. A p p l i c a t i o n
factors for some pesticides show that the h i g h e s t c o n c e n t r a t i o n w i t h o u t a n y toxic effect
m a y be more t h a n two orders of m a g n i t u d e lower t h a n the 96-h LC50 ( H a n s e n & Parrish,
1977; N i m m o et al., 1977).
Levels of p o l l u t a n t s i n the e n v i r o n m e n t a p p e a r to be extremely low c o m p a r e d with
those that prove effective i n toxicological laboratory experiments. A comparison is m a d e
310
W. Ernst
in F i g u r e Y in o r d e r to t e n t a t i v e l y e v a l u a t e a toxic p o t e n t i a l r e p r e s e n t e d b y some o r g a n i c
c h e m i c a l s in the sea. T h e a c t u a l concentrations of t h e s e p o l l u t a n t s in s e a w a t e r cover the
r a n g e from those in t h e o p e n s e a a n d estuaries. T h e e x p e r i m e n t a l toxic concentrations
are LC50 v a l u e s for fish or those o b t a i n e d b y m o r e sensitive criteria. It can b e c o n c l u d e d
from F i g u r e Y that in the o p e n s e a t h e r e are m o r e t h a n four orders of m a g n i t u d e b e t w e e n
e n v i r o n m e n t a l a n d a n y toxic levels, a safety m a r g i n w i d e e n o u g h to p r e c l u d e a n y toxic
effect. H o w e v e r , t h e s e "safety m a r g i n s " a r e s u b s t a n t i a l l y s m a l l e r in e s t u a r i e s a n d
coastal a r e a s a n d b e c o m e a d d i t i o n a l l y r e d u c e d b y t h e f o l l o w i n g a s s u m p t i o n s : (a) toxic
actions m u s t not b e c o n s i d e r e d for a s i n g l e s u b s t a n c e b u t for m a n y s u b s t a n c e s s i m u l t a n e ously present, e a c h c o n t r i b u t i n g a n a d d i t i o n a l toxic potential; (b) b i o m a g n i f i c a t i o n of
p e r s i s t e n t c o m p o u n d s in the food c h a i n must b e c o n s i d e r e d ; e s p e c i a l l y s u b s t a n c e s
e x h i b i t i n g half-life t i m e s of m o r e t h a n a b o u t t w e n t y d a y s m a y b e c o n c e n t r a t e d in
p r i m a r y a n d h i g h e r c o n s u m e r s so that toxic effects m a y occur at concentrations l o w e r
t h a n those r e p r e s e n t e d in F i g u r e Y; (c) c e r t a i n s p e c i e s m a y e x h i b i t a h i g h e r d e g r e e of
b i o c o n c e n t r a t i o n t h a n a test s p e c i e s chosen; (d) e s t u a r i n e s e d i m e n t s c o n t a i n h i g h
concentrations of p o l l u t a n t s that contribute to h i g h e r levels in b i o t a v i a b e n t h i c food
chains; (e) p o l l u t a n t s w h i c h a r e at p r e s e n t u n d e t e c t a b l e w i l l contribute to a h i g h e r total
l o a d e s p e c i a l l y in estuaries; (f) stress factors, such as low o x y g e n concentrations, w i l l act
t o w a r d s a h i g h e r toxic potential.
CONCLUSIONS
F r o m the results p r e s e n t e d in this p a p e r the f o l l o w i n g conclusions can b e d r a w n :
(1) The l o a d of o r g a n i c s u b s t a n c e s in s e a water, s e d i m e n t s a n d b i o t a can n o w b e
m e a s u r e d b y h i g h l y s p e c i a l i z e d a n a l y t i c a l t e c h n i q u e s . C o n c e n t r a t i o n s in s e a w a t e r
d e p e n d on d e p t h a n d location; e s t u a r i e s e x h i b i t c o n s i d e r a b l y h i g h e r c o n c e n t r a t i o n s t h a n
o p e n s e a water.
(2) M e t a b o l i c d e g r a d a t i o n d o e s occur in m a r i n e organisms, e v e n w i t h h i g h l y p e r s i s t e n t
m o l e c u l e s a l t h o u g h to a l e s s e r extent.
(3) P r e d i c t i o n of b i o c o n c e n t r a t i o n p o t e n t i a l s c a n b e a c h i e v e d b y the u s e of p a r t i t i o n
coefficients a n d s o l u b i l i t y data. Short-term e x p e r i m e n t a l w o r k in this field will b e
accelerated by kinetic approaches.
(4) B i o m a g n i f i c a t i o n of s u b s t a n t i a l l y p e r s i s t e n t c o m p o u n d s a l o n g food chains is l i k e l y to
occur w i t h i n c r e a s i n g e l i m i n a t i o n half lives of the substances.
(5) R e l a t i o n s h i p s b e t w e e n the a c u t e 96-h LCs0 a n d chronic toxicity c a n b e d e s c r i b e d b y
specific a p p l i c a t i o n factors, d e t e r m i n e d for i n d i v i d u a l substances.
(6) C o n c e n t r a t i o n s of a n u m b e r of o r g a n i c p o l l u t a n t s found in the o p e n o c e a n are
u n l i k e l y to e n d a n g e r m a r i n e life.
[7) T h e e s t u a r i e s d e s e r v e s p e c i a l attention: on the b a s i s of chronic toxicity d a t a a n d
realistic concentrations of the substances, a safety factor of 100-1000 s e e m s l i k e l y to b e
realistic. A m o r e d e t a i l e d i n v e s t i g a t i o n r e v e a l s a n u m b e r of facts that will d r a s t i c a l l y
r e d u c e this "safety m a r g i n " . In c o n n e x i o n w i t h f i n d i n g s that d i s o r d e r s in fishes are
i n c r e a s i n g , it can b e c o n c l u d e d that e s t u a r i n e p o l l u t i o n m a y e x e r t d e t r i m e n t a l effects on
m a r i n e organisms. B e c a u s e t h e r e are still c o n s i d e r a b l e g a p s in our k n o w l e d g e , it is
difficult to m a k e r e l i a b l e predictions. Basically, w o r k in this field r e q u i r e s g e n e r a l i z a tion a n d simplification so t h a t one can v i e w the c o m p l e x i t y of i m p o r t a n t p r o c e s s e s
E f f e c t s of p e s t i c i d e s
311
h o l i s t i c a l l y . O n t h e o t h e r h a n d , c o n c e p t s or m o d e l s t h a t w i l l a c c o u n t for t h e m a j o r i t y of
experimental findings will be helpful in promoting future research.
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