Chlorinated hydrocarbon residues in the fish of lake Tanganyika

Chlorinated Hydrocarbon Residues in the Fish of Lake Tanganyika

by H. DEELSTRA% JAMES L. POWER 2, and C. T. KENNER 3 1Universitaire Instelling /lntwerpen, 2610 Wilrijk, Belgium

~Dallas District, Food and Drug Administration, Dallas, Tex. 75204 ~Southern Methodist University, Dallas, Tex. 75275

INTR ODUC TION

The use of chlorinated hydrocarbon pesticides for the

control of tropical diseases and the treatment of agricultural crops in Central Africa has [ncreased tremendously since it was

started in 1954 (LAMBRECHT, 1954; BRION, 1962). Even though the levels of residues from such pesticides have been

studied extensively in many parts of the world, there are few

data frorn this region (KOEMAN and PENNINGS, 1970; EVERAARTS, et al., 1971; KOEMAN, et al., 1971, 197Z). The purpose of this study was to determine the level of pesticides

over a period of time in the fish in the northern portion of Lake

Tanganyika which are used as a source of prote[n by the surround- ing populations. Lake Tanganyika should make an excellent study

area since it[s almost a closed system and is surrounded by

cotton plantations, especially at the northern end.

AREA AND SCOPE OF STUDY

L a k e T a n g a n y i k a , s [ t u a t e d in the R i f t V a l l e y of A f r i c a , i s 650 k m l o n g a n d up to 70 k m w i d e ( s e e F i g u r e 1). T h e s u r f a c e i s a p p r o x i m a t e l y 800 m a b o v e s e a l e v e l a n d the l a k e h a s a m a x i m u m d e p t h of 1500 m a n d a n e s t i m a t e d v o l u m e of 30, 000 k m 3. T h e a n n u a l r a i n f a l l of a p p r o x i m a t e l y 1 m a n d r i v e r i n f l o w f r o m t he R u z i z i a n d M a l a g a r a s i r i v e r s c o u l d r a i s e t h e l e v e l b y 0 . 5 m p e r y e a r e x c e p t f o r l o s s b y e v a p o r a t i o n (95 %) a n d d r a i n a g e i n t o t he L u k u g a r i v e r (5 %). T h i s s m a l l d r a i n a g e m a k e s t he l a k e s i m i l a r to m a n y c l o s e d s y s t e m s . T h e w e t s e a s o n in t he n o r t h e r n p a r t of the l a k e s t a r t s n e a r the f i r s t of O c t o b e r a n d t h e d r y s e a s o n n e a r the 20th of May. The water chemistry of the lake is described by

several authors (BEAUCHAMP, 1940, 1964; KUFFERATH, 1952;

CAPART, 1952; TALLING and TALLING, 1965; DEGEN, et al.,

1971) .

D u r i n g t he c o t t o n s e a s o n of 1 9 7 1 - 7 2 ( p r i m a r i l y in M a y ) , t he c o t t o n f i e l d s i n B u r u n d i a t t he n o r t h e r n e n d of t he l a k e w e r e

689

Bulletin of Environmental Contamination & Toxicology, Vol. 15, No. 6 �9 1976 by Springer-Verlag New York Inc.

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~ ~ ~ � 8 "~ R W A N D A

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__~~~, .~ Bujumbura x~ UViP.~ ',1, .~

Z A ‡ B A R A K A

B BURTOA

RUMONGE

KALE

0 1 0 0 k m

= \

KIGOMA

~ J I J , M4Z4GAR'&~;

T A N Z A N I A EDITH BAY

j r 4 . .p -P 4"~ .t..t. 4 . .p 4. Jf �9 Jr 4- 4" "P "~P

SUMBL~

Z A M B I A MPULUNGU

Figure i. Lake Tanganyika

690

t r e a t e d wi th a to t a l of 3 0 , 9 0 0 kg of DDT, 9 , 2 0 0 kg of endosu l f an , 4, 200 kg of end r in , 1 ,000 kg of ke l ton , and 600 kg of m e t a s y s t o x . R e s i d u e f r o m t h e s e p e s t i c i d e s could r e a c h the lake by d i r e c t con - t a m i n a t i o n f r o m a e r i a l s p r a y but the g r e a t e s t s o u r c e is the r u n - off f r o m t r e a t e d f i e ld s in the p la ins a long the R u z i z i r i v e r . P e s t i c i d e s can a l s o e n t e r the lake w a t e r by u n a u t h o r i z e d d i s p o s a l and by a c c i d e n t s u c h as the s p i l l a g e of 6 , 5 1 0 l i t e r s of p e s t i c i d e s o l u t i o n s due to a boa t a c c i d e n t in F e b r u a r y 1972.

The lake has b e e n u s e d s ince 1970 as a s o u r c e of d r i n k i n g w a t e r f o r B u j u r n b u r a (popu la t i on 80 ,000) but the m a j o r i n g e s t i o n of p e s t i c i d e r e s i d u e s by the p o p u l a c e p r o b a b l y co rnes f r o m the c o n s u m p t i o n of d r i e d f i s h w h i c h [s an i m p o r t a n t e l e m e n t of t h e i r da i ly d ie t . In B u r u n d i t h e f i s h c a t c h p e r y e a r r a n g e s f r o m 12 ,000 tons to 17 ,000 tons ( C O U L T E R , 1970). E i g h t y - f i v e p e r cen t of th i s t o t a l c a t c h c o n s i s t s of two c lupe id s p e c i e s : S t o l o t h r i s s a t a n g a n i c a e R e g a n ( c o m m o n l y ca l l ed ndaga la ) and L i m n o t h r i s s a m i o d o n B o u l e n g e r (known as l umpu) . T h e i r p r e d a t o r s , the L a t e s ( ca l l ed s a n g a l a ) and the L u c i o l a t e s s t a p e r s i i Boulenger_ ( c e n t r o - p o m i d a e ) ( c a l l ed m u k e k e ) r e p r e s e n t 5% and 10% r e s p e c t i v e l y of the c a t c h . T h e s e s p e c i e s a r e al l e n d e m i c to the l ake .

The S t o l o t h r i s s a and L i m n o t h r i s s a o c c u r t o g e t h e r but the S t o l l o t h r i s s a c o n s t i t u t e s the l a r g e s t f r a c t i o n of the o f f s h o r e c a t c h whi le the L i m n o t h r i s s a is m o r e a b u n d a n t in the c a t c h e s c l o s e r to the s h o r e l ine . G r o w t h r a t e and s u r v i v a l da ta i n d i c a t e tha t bo th l ive abou t one y e a r and tha t the adu l t s a r e m o s t abundan t wh› the p l a n k t o n c o n c e n t r a t i o n [s the g r e a t e s t , The c l u p e i d s f eed on z o o - p l a n k t o n and p h y t o p l a n k t o n but the L u c i o l a t e s s e e m to feed on the c l u p e i d s e x c l u s i v e l y . T r a d i t i o n a l l y , the m a j o r i t y of the c l u p e i d s and the young L u c i o l a t e s a r e s u n - d r i e d and e a t e n whole . •ddi - t i ona l d e t a i l s of the b i o l o g y and e c o l o g y of t h e s e f i s h s p e c i e s c an be found in the w o r k s of P O L L (1953), M A R L I E R (1957), COLLART (1958), COULTER (1966, 1970), MATTHES (1967), and ELLIS (1971).

Samples of f[sh were obtained from the commercial fish- eries operating in the northern end of the lake at var[ous times during 1971-2-3. The clupe[ds were adult specimens and the Luciolates were juveniles of approximately the same size as the clupeids. They were dried whole on cernent floors in the sun for two or three days and were analyzed for residual moisture, nitrogen, lipids, ash, and pesticides.

691

E X P E R I M E N T A L

The p e r c e n t a g e of w e i g h t l o s s ( m o i s t u r e ) d u r i n g s u n - d r y i n g w a s d e t e r m i n e d by w e i g h i n g the f i s h b e f o r e and a f t e r e x p o s u r e . The r e s i d u a l m o i s t u r e w a s o b t a i n e d b y h e a t i n g w e i g h e d , f i n e l y p o w d e r e d s a m p l e s of the s u n - d r i e d f i s h at 105~ f o r 24 h o u r s , f o l l o w e d b y i g n i t i o n f o r t h r e e h o u r s a t 500 ~ to d e t e r m i n e the a s h c o n t e n t . The t o t a l n i t r o g e n w a s found b y the K j e l d a h l m e t h o d and the l i p id c o n t e n t b y the p r o c e d u r e of F O L C H , e t a l . (1957) . The v a r i a t i o n of c r u d e f a t c o n t e n t of L i m n o t h r i s s a c a u g h t d u r i n g 1973 w a s a l s o d e t e r m i n e d b y t h e F O L C H , et a l . (1957) e x t r a c t i o n m e t h o d .

The chlorinated hydrocarbon residues were determined (except for the column substrate used) by the BERTUZZI, et al. (1967) modification of the MILLS, et al. (1963) method routinely used by the Food and Drug Administration for pesticide analysis. The fishwere extracted with 35:65 water-acetonitrile, partitioned into petroleum ether, adsorbed on fluorisil, and eluted with ethyl ether-petroleum ether (6 f0 and 15 %). Aliquots of these solutions were injected into a Barber-Colman Model 5000 Gas Chromato- graph which contained a 6 ft x 4 mm glass column of (2+I) 15 % Q F - 1 (10, 000 c s t ) , 5% DC 710 (10, 000 c s t ) on 8 0 / 1 0 0 m e s h G a s - C h r o m W (HP) and w a s f i t t e d w i th an e l e c t r o n - c a p t u r e d e t e c t o r .

Twenty-seven oven-dried (105~ flour samples of fish caught during November and December of 1971 and 18 samples of flours of sun-dried Limnothrissa caught between January and December of 1972 were analyzed for pesticides. Also, four of the oven-dried samples were analyzed for heavy metals by the BAETZ and KENNER (1973) method and the flour of one sun-dried adult specimen of Tilapia Tanganicae caught soon after the 1972 accident was analyzed for pesticide residues.

RESULTS AND DISCUSSION

The average per cent of moisture lost by drying in the sun was 74.9 70 for the Stolothrissa, 73.5 % for the Limnothrissa, and 74.0% for the Luciolates. The average compositions of the sun- dried fish flours are shown in Table I.

The seasonal variation of crude fat in fish flours from catches during 1973 is shown in Table Il.

692

T A B L E I

A v e r a g e C o m p o s i t i o n of S u n - d r i e d F i s h F l o u r s

_Specie'

S t o l o t h r i s s a L i m n o t h r i s sa L u c i o l a t e s

R e s i d u a l M o i s t u r e P r o t e i n L ip ids A s h ..... 10s ~ (%) ~0 % ~0

8 . 3 6 9 . 7 6 . 3 1 4 . 6 9 . 9 6 3 . 3 s . z 13.s

8 . 8 70 .1 6 .5 13 .9

V a r i a t i o n

TAB LE II

of Crude Fat in Fish Flour of Limnothrissa Caught in 1973

Date of P l a c e of R e s i d u a l M o i s t u r e C r u d e F a t C a t c h C a t c h 105 ~ % %

January 26 Minago 7.3 13.4 February 28 Minago 9.0 4.39 March 14 I4itaza 8.6 7.19 April 26 Minago 12.5 4. 12 May 26 Minago 13.3 5.15 July 20 14itaza 10.5 4.04 A u g u s t 8 R u t u n g a 8 .6 6 .51 S e p t e m b e r 8 M a g a r a 11 .2 9 . 8 8 O c t o b e r 31 t™ 11 .6 9 . 8 8 N o v e m b e r 18 M a g a r a 1 4 . 8 6 . 0 0 D e c e m b e r 5 M i n a g o 11.5 4 .81

A v e r a g e i0.8 6 . 8 4

The results of the pesticide analysis of the oven-dried fish flour samples are shown in Table III. These values may be low due to the loss of pesticides by vaporization or codistillation (EVERAARTS, et al., 1971) during the oven-drying procedure. Except for the fish caught near Minago, there is a general decrease in the total amount of DDT (o, p~-DDT + p, pI-DDT) and its metabolites (DDE and TDE) as the distance inr from Bujumbura or the head of the lake. The average total DDT + DDE + TDE is approximately the same for Limnothrissa and Stolo- thrissa which feed on plankton and this average is more than twice the average for Luciolates which feed on the clupeids. Trace amounts (0.01-0.03 ppm) of endrin were round in some of these samples.

693

TABLE

III

Chlorinated H

ydrocarbon Residues in Oven-dried Fish F

lour From Lake Tanganyika

Bujumbura

Kitaza

Rutunga

Magara

Minago

Kagongo

27 k

m I

34 k

m I

43 k

m I

53 km i

60 k

m i

DDE

Specie z

+TDE

Limnothris sa

Muguraka

113 km I

Amounts

Found

(ppm)

DDE

DDE

DDE

DDE

DDE

DDE

DDT 3'4 +TDI~ DDT 3'4 +TDE DDT 3'y +TDE DDT3'4+TDE DDT3,4+TDE DDT3,4+TDE DDT 3'4

0.53

0.09

0.44

0.05

0.48 0.06

0.90 0.15

0.32

0.02

0.30 0.06

0.89

0.44

0.74 0.35 0.45

0.24

0.58

0.24

%

Stolothrissa 0.49

0.15

0.56

0.18

0.66

0. ii

0.53 0.36

0.38 0.07 0.41

0.22

0.59

0.50

0.44 0.29 0.47

0.26

0.43 0.09

Luciolates

0.32

0.02

0.17 0.03

0.53 0.07 0.20

0.04 0.20

0.02

0.35

0.25

0.28

0. Zl

IDistanee f

rom Bujumbura

ZCaught during November and December 1971.

p2

3Includes both o, pt-DDT and p, pS-DDT.

Percentage of total due to o,

DDT ranges from 0 to 5

0%

with an average of 17% and a median of 14~

4Average total DDT + DDE+TDE

is 0.70 for Limnothrissa, 0.73 for Stolothrissa, and 0.38 for

Luciolate s.

The results of the heavy metal analysis on the flours from

four samples caught off K agongo in November 1971 are shown in

Table IV. No lead, cadmium, nickel, or cobalt were detectedin any

of these samples. The results of the analysis of the sun-dried

TABLE IV

Heavy Metal Analysis of Oven-dried Fish Flours

Amounts round (ppm)

Specie Cu Fe Mn Zn

Limnothrissa I 0.04 0.67 0. 15 l. 27

Limnothrissa 2 0.06 0.74 0.11 i. 23 Luciolates z 0.04 l. 83 0.08 i. 00

Stolothrissa • 0.08 I. 42 0. 13 i. 29

•Caught c l o s e to s h o r e .

ZCaught i0 k m off s h o r e .

f l o u r s of L i m n o t h r i s s a c a u g h t d u r i n g 1972 a r e shown in T a b l e V. The a m o u n t of T o t a l DDE + T D E + DDT v a r i e d f r o m 0 .45 pprn to 2 . 3 9 p p m wi th an o v e r a l l a v e r a g e of 1 .30 p p m . The D D E + T D E was a l w a y s g r e a t e r than the DDT (o, p t - D D T +p, p~-DDT) wi th the DDT a v e r a g i n g a p p r o x i m a t e l y 25 % of the t o t a l of t h e s e i s o m e r s . The a v e r a g e t o t a l a m o u n t s d e c r e a s e d the f u r t h e r the c a t c h was f r o m B u j u m b u r a w h i c h i n d i c a t e s tha t the p r i m a r y c a u s e of r e s i - dues is r u n - o f f f r o m the t r e a t r a e n t of the co t ton f i e ld s a l o n g the R u z i z i p la in . The t o t a l a m o u n t s of c h l o r i n a t e d h y d r o c a r b o n s a v e r a g e d 0 . 6 0 p p m f r o m J a n u a r y t h r o u g h e a r l y A p r i l but fe l l to an a v e r a g e of 0 . 4 7 p p m in la te A p r i l and then i n c r e a s e d f r o r n June t h r o u g h S e p t e m b e r to an a v e r a g e of 2 . 0 4 p p m . F r o m O c t o b e r t h r o u g h D e c e m b e r the a v e r a g e was 1 .30 p p m . The s a m p l e s c a u g h t b e t w e e n June and J u l y c o n t a i n e d s m a l l a m o u n t s ( 0 . 0 2 to 0 .17 ppm, a v e r a g e 0 .07) of o t h e r c h l o r i n a t e d h y d r o c a r b o n s ( d i e l d r i n , end r in , l i ndane ) . The s a m p l e caugh t S e p t e r n b e r 29 off t™ had 0 .65 pprn of t h e s e p e s t i c i d e s and was e x c l u d e d f r o m the a v e r a g e .

The a n a l y s i s of the s u n - d r i e d f l o u r f r o m the adu l t T i l ap i a c a u g h t soon a f t e r the s p i l l a g e a c c i d e n t in the lake showed (in ppm) DDE-I.57; TDE-7.54; o, pt-DDT- 1.97; p, pt-DDT- 17.83; diel- drin-0, ll; lindane-0.18; endrin 3.55; total 32.75.

The results on the sun-dried sarnples of the fish used as a source of protein indicate that the amounts of chlorinated pesti- cides present are below the allowable limits set in most countries. On the basis of the fresh fish, assuming an average loss during

drying of 75 %, the values are all less than 0.6 ppm. The

695

TAB LE V Chlorinated I-lydrocarbon lqesidues in Sun-dried Limnothrissa

Date of catch

(1972)

Feb. Il Feb. 24 April 6

April 16

June 6

July 5 Aug. 3

Sept. 13

Sept. 29

Oct. 12 Oct. 31 Nov. 17

Dec. 30

Avg.

From Lake Tanganyika

Amounts found (ppm) DDE DDE + +

TDI~ I DDT z Total TDE I DDT Total

Bujumbura -- I™ 27 km 3

I. 29 i. 02 2.31

0.81 0.92 i. 74

0.92 1.14 2.06

2.04

l. Zl 0.97 2.18 1.20 l. 19 2.39 I. 00 0.63 l. 63

0.96 0.34 I. 30 0.87 0.37 i. 24 i.ii 0.81 1.92

0.51 0.55 1.06

I. 67

DDE +

TDE I DDT Total

Rutunga 34 km 3

0.57 0.19 0.76 0.66 0.25 0.91 0.62 0.45 1.07

0.31 0.14 0.45

0.55 0.38 0.93

0.82

Magara Kagonga 43 km 3 60 km 3

Jan. 26 April 6 0.63 0.40 I. 03 April 16 0.31 0.18 0.49

Avg. 0.76

0.49 0.20 0.69

0.69

74.5% of the DDE+ TDEfor all 1DDE percentage averages

s ample s.

ZIncludes both o, pt-DDT and p, pt-DDT. Percentage of total due to o, p~-DDT ranges from 0 to 9 with average of 4% and a

median of 5 %.

3Distance from Bujumbura.

extremely high values round in the Tilapia indicates that fish

caught in the area of such accidents soon after the accident should hot be eaten.

The amino acid, fatty acid, and minerai content of these fish are being published separately (DEELSTRA, in press).

696

A c k n o w l e d g m e n t s

The a u t h o r s w i s h to t h a n k D r . C. W. C o u l t e r , P r o j e c t M a n a g e r of the L a k e T a n g a n y l k a r e s e a r c h t e a m of the F . A . O . in B u j u m b u r a f o r c o l l e c t i n g and s e n d i n g the f i s h s a m p l e s . One of the a u t h o r s , H . D . , i s p l e a s e d to a c k n o w l e d g e t e c h n i c a l s u p p o r t b y the F . A . O . d u r i n g h is s t a y in B u j u m b u r a ( 1 9 7 1 - 7 2 ) . T h e y f u r t h e r t h a n k I r . V. P h i l e m o t t e , of C o g e r c o - B u r u n d i , f o r the i n f o r m a t i o n a b o u t the c o n s u m p t i o n of p e s t i c i d e s d u r i n g the co t t on c a m p a i g n .

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697

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698