Bioconcentration and elimination of bis(tributyltin)oxide (TBTO) and triphenyltin chloride (TPTC) in several marine fish species

Wa:. Res. Vol. 26, No. 12, pp. 1589-1595, 1992

0043-1354/92 $5.00 + 0.00

Printed in Great Brttain. All rights reserved

Copyright C 1992PergamonPress Ltd

BIOCONCENTRATION AND ELIMINATION OF BIS(TRIBUTYLTIN)OXIDE (TBTO) AND TRIPHENYLTIN CHLORIDE (TPTC) IN SEVERAL MARINE FISH SPECIES HISASHIYAMADAand KAZUFUMITAKAYANAGI Environment Conservation Division. National Research Institute of Fisheries Science. 6-31-1, Nagai, Yokosuka. Kanagawa, 238-03, Japan (First recei,'ed August 1991; accepted in ret'ised form May 1992) Abstract--Pagrm major, Mugil cephalus and Rudarius ercodes were exposed to bis(tributyltin)oxide (TBTO) and triphenyltin chloride (TPTC) for 8 weeks in a flow-through aquarium system. The bioconcentration factors (BCFs) of TBTO and TPTC and the elimination rate constant of TBTO for these fish were determined. The BCF of TBTO ranged from 2400 to I !,000 depending on the fish species and the concentration in the rearing seawater. Out of the three, P. major had the smallest elimination rate constant (0.024 day -I) and bioconcentrated the largest amount of TBTO (BCF: 9400-11,000). On the other hand, the BCF of TPTC of the two fish species examined was similar: 3100-3300 for P. major and 4100 for R. ercodes. These BCFs of TBTO and TPTC of P. major were larger than the values previously reported. TBTO and TPTC were the least accumulated in muscle among the tissues and organs of P. major examined, and no correlation was found between the lipid content and the accumulated TBT or TPT content.

INTRODUCITON Organotin compounds such as tributyltin (TBT), triphenyltin (TPT), and tricyclohexyltin have been widely used in diverse industries as biocides, heat stabilizers for polyvinyl chloride and catalysts in a variety of chemical reactions (Blunden and Chapman, 1986). In particular, the use of tributyltin and triphenyltin as antifouling agents in boat paints has been widespread because of their superior effectiveness compared to previously used copper oxide paints. The presence of organotin compounds in coastal environments has been reported in seawater (Champ and Pugh, 1987; Batley et al., 1989a; Cleary and Stebbing, 1985, 1987; Alzieu et al., 1989), in sediments (Langston et al., 1987; Makkar et al., 1989) and in organisms (Langston et al., 1987; Barley et al., 1989b). Champ and Pugh (1987) summarized the TBT concentrations in several seawater regions. The TBT concentrations in seawater of several areas, such as coastal waters, harbors and marinas, fall in the range from the detection limit to 1.3/~g/I. TPT has also been detected in the coastal waters of Japan: the concentration ranged from 0.005 to 0.088/~g/I in seawater, from 0.001 to !.1/~g/g in sediments and from 0.02 to 2.6/zg/g in fish (Environment Agency of Japan, 1989). Organotin compounds are known to be considerably bioconcentrated in mussels (Waidock and Thain, 1983; Laughlin and French, 1988) and snails (Bryan et al., 1987). Wade et ai. (1988) found as high as 1.5 mg/g of TBT in mussels collected in Hawaii. WR 26/12--C

The bioconccntration of the organotin compounds by freshwater fish has been studied extensively. Tsuda et al. (1988) reported that a large amount of TBTO was bioconcentrated in the kidney of Cyprinus carpio (carp) and the BCF was 3200, 1300, 600 and 500 for kidney, gall bladder, liver and muscle, respectively. Martin et al. (1989) reported that Salmo gairdneri (rainbow trout) bioconcentrated TBTO during a 64 day exposure at a TBT concentration of 0.525/~g/I and the BCF was 406. Tas et al. (1990) determined the BCF of triphenyltin hydroxide by Poecilla reticulata (guppy) and S. gairdneri by the method of uptake and elimination kinetic analysis and also by a 30-day exposure experiment. The same BCF was determined by both methods, and was 2100 for P. reticulata and 650 for S. gairdneri. For the brackish water species, Cyprinodon variegatus (sheepshead minnow), the BCF of TBTO was 2600 (Ward et al., 1981). On the other hand, only a few reports have been published for the bioconcentration of tributyltin compounds and their elimination by marine fish. Moreover, bioconcentration of triphenyltin compounds in marine fish has not been studied. Because organotin compounds are mainly released to the marine environment directly from antifouling paints on ships, more detailed studies on the bioconcentration of organotin compounds in marine fish are necessary, especially for the consideration of an ambient water quality target in the marine environment. In this research, we report the bioconcentration of TBTO and TPTC and the elimination of TBTO by three kinds of marine fish.

1589

1590

HtSASH] YAMADAand KAZUFUMITAKAYANAGI Table I. The experimental conditions: body weight, organotin concentration in the rearing seawater and water temperature Organotin compounds

TBTO

Species

Pagrus major

I 2 3

Mugil cephalus

4

Radarius ercodes TPTC

Exp. No.

Pagrus major Rudarius ercodes

Initial body weight (g) 11.7-4- I.I 12.2 ± 1.7 1.5 ±0.5 3.2 ± 0.8 0.08 0.30 13.3+2.7 24.3 + 3.4 I.I + 0.2

5 6 7 8 9

Organotin concentration (ngA) 37.9__.8.1 659 _+ 122 89.1 _+ 1 2 . 2 122 _+ 16 106 _+ 14 116 _+ 17 1650_+190 63.3 _+9.6 148 + 17

Water temperature CC) 21.2±0.8 20.1 ± 0.8 20.7+0.5 22.6 ± I.I 20.7 _+0.5 20.7 ± 0.5 24.5_+0.5 24.5 ± 0.5 19.8 -+ 0.1

TBTO: bis(tributyltin)oxide: TPTC: triphenyltin chloride. MATERIALS AND METHODS

Chemicals Bis(tributyltin) oxide (TBTO) and triphenyltin chloride ('TITC) were obtained from Aldrich Chemical Company Inc. (Milwaukee, Wis., U.S.A.) and Tokyo Chemical Inc. (Tokyo, Japan), respectively. The purities o f TBTO and TPTC were 96 and 98%, respectively, according to the manufacturers. These compounds were used without further purification.

Test fish In this research, Pagrus major (red sea bream), Mugil cephalus (mullet) and Rudarius ercodes (filefish) were used as test organisms. Pagrus major was obtained from Kanagawa Prefectual Fisheries Research Station. They were spawned, hatched out artificially and fed at the above Fisheries Station before the experiments. Mugi/ cephalus and R. ercodes were collected from tidal pools and seagrass beds, respectively. They were fed on formula feed before the experiments. The body weights are shown in Table I. All the fish are considered juvenile.

Test system and rearing offish Experiments were carried out under a continuous flowthrough system as shown in Fig. I. Seawater flows through a PVC pipe containing activated carbons in order to remove contaminants in the original seawater. The seawater

temperature was maintained at 20 or 25°C by using a thermocontroller. The temperature-controlled seawater was supplied to 50 I. aquaria at a rate o f 500 ml/min. TBTO and TlrrC were dissolved in a mixture o f acetone-dimethylsulfoxide (1:9) and 0.5-1.0ml o f these organotin solutions were diluted with 20 I. o f well-aerated tap water. The diluted solutions were supplied to the aquaria at a rate of 5 ml/min by using a micro glass pump (Tokyorikakikai, GMW-16A). The lowest concentrations o f TBT and TPT in the rearing seawater in these experiments were maintained at 1/100-1/200 o f the LC~o (48 h) value for P. major. The LC~ (48 h) values of TBTO and TPTC for P. major were 3.9 and 12.6/~g/I, respectively. The concentrations of TBT and TPT in the rearing seawater were determined every week and are shown in Table I. The fish were raised for 8 weeks in seawater containing TBT or TPT. The fish were then raised for 2-4 more weeks in TBT-free seawater (the TBT concentration in this seawater was 5.7 + 2.8 ng/I) in order to determine the elimination rate of TBT from the fish. The fish were fed with the formula feed: 30 mg food/g fish/day. Air was introduced into the aquaria to maintain an adequate dissolved oxygen level in the rearing seawater. Under these conditions, none o f the fish showed any signs o f tiredness or agitation during the experiment. The concentrations o f TBT and T I T in the fish were determined every 2 weeks during the bioconcentration experiment. During the elimination experiment, the concentration of TBT in the fish was determined every week.

3

#

II h

8

~

8

Fig. I. The continuous flow-through system used in this research, l, Polyvinyl chloride pipe containing activated carbon; 2. thermocontroller; 3. polyvinyl chloride pipe; 4, cock. 5; micro glass pump; 6. TBTO or TPTC stock solution: 7. funnel; 8. aquarium; 9, overflow; and 10. air.

Bioconcentration and elimination of TBTO and TPTC in fish

1591

8ESULTS A,~D msct'SSION

For M. cephalus and R. ercodes, the TBT concentration was also determined on the third day.

T B T and T P T concentrationsm fish

Chemical analysis TBT and TPT were analyzed by the method described by Takami et al. (1988). TBT and TPT dissolved in seawater were extracted with a mixture of ethylacetate-n-hexanc (3:2 v/v). The extracted organotin compounds were purified with both anion and cation ion-exchange resins. They were then converted to propyl derivatives with Grignard reagent. and were analyzed with a high resolution gas chromatograph equipped with a flame photometric detector. in order to extract TBT and TPT from fish, a fish was homogenized with I N hydrochloric acid in a methanol-ethylacetate ( l : l v / v ) mixture. The extracted organotin compounds were purified and analyzed as described previously for the seawater samples. The quantification of TBT and TPT was based on the known amount of tetrabutyltin GC standard present. The average recovery of spiked TBT and TPT in seawater was 76 and 92%. respectively, at 0.5 pg/I, and the average recovery from fish was 81% for TBT and 73% for TPT at 0.6pg/g. The coefficient of variation by this procedure was less than 5%. The detection limit of this method was 5 ng/I in the rearing seawater and 0.01/~g/g in the fish. The lipid content was determined by the chloroform+methanol extraction method described by Bligh and Dyer (1959). The lipid content in the whole body of P. major, M, cephalus and R. ercodes was 10-1 I. 9~11 and 7%. respectively, at the end of the experiment.

BCF and elimination rate constant cal('uhttions A BCF was calculated by the following equation: BCF. = iCE. - CB. )/C.

( I)

where BCF. is the BCF at the nth week. CE. is the concentration of TBT (TPT) in Ihe experimental fish at the nth week, CB. is the concentration of TBT (TPT) in the control fish at the nth week and C. is the mean concentration of TBT (TPT) in the rearing seawater during the 8-week bioconcentration experiments. The elimination rate constant (k:) was calculated from the following equation:

C/,

C/oc '"

=

(2)

where C/o is the TBT concentration in the fish at the start of the elimination experiment, Cr, is the TBT concentration in the fish at t time of the elimination experiment, z is the period of the elimination experimental and k 2 is the elimination rate constant.

Changes in the T B T c o n c e n t r a t i o n in P. major,

M. cephalus and R. ercodes are shown in Fig. 2. The T B T concentration in P. major in the control was less than 0.03/~g/g and decreased gradually with time (Exp. I). O n the other hand, the T B T concentrations in the experimental fish increased significantly with time. These results clearly indicate that T B T can be accumulated from the seawater by these fish. The T B T concentration in M. cephalus increased from 0.06pg/g at the beginning of the experiment to 0.37 + 0.03 pg/g at week 8 (Exp. 4). The change in T B T concentration in R. ercodes was similar to that in M. cephalus.The T B T concentration in R. ercodes (Exp. 6) increased from 0.03 to 0.37+0.04pg/g during the 8-week period [Fig. 2(D)]. As shown in Fig. 2(C) and (D), no significantchange in the T B T concentration was found between small R. ercodes (Exp. 5) and large R. ercodes (Exp. 6). The change in T B T concentration in M. cephalus and R. ercodes was small from the 6th to the 8th week, suggesting that thc T B T concentration in M. cephalu.~and R. ercodes has reachcd an equilibrium. On the other hand, the T B T concentration in P. major (Exp. I) increased from 0.03 pg/g at the beginning to 0.41 -b 0.I I pg/g at thc 6th wcck and dccrcascd to 0.36 + 0.01 pg/g at the end (8th wcck) [Fig. 2(A)]. It is not clear whether the T B T concentration has reached an equilibrium during the 8-week period. A longer experimental period may be needed to reach an equilibrium. By using the method of Connel 0988), a theoretical period to reach an equilibrium can bc calculated from the elimination rate constant (k2). It was 192 days for P. major, 89 days for M. cephalus and 49-59 days for R. ercodes. It is well known that marine fishdrink seawater for regulation of osmotic pressure. Maetz (1970) estimated the a m o u n t o f seawater d r u n k by Fund/us heteroclitus a n d Tilapia mosambica acclimated to 0.5[- R. ercodes(smal|)

0.6 A (Exp. 1)

~o3 / +

P, major

0.5

B (Exp. 4)

0.4

M. cephalus t

(11

+

0.3 0.2

,+

=-- 0.1

¢

•

@

•

0

2

4

01

t

¢ 10000 lu..

~,

tl

;

8

°

0"2t

¢

¢

¢

0]4000

-,

•

i

i

+ i

o.,r. (Exp.s) 1_~

+

o 0.5[ R. ercodes(large)

. ++

0.2

~o.t +

O

+

],ooo~ ::+ "+.11

it 0

0"lie

(Exp. 61 ,

Experimentalperiod (week) Fig. 2. Changesin the TBT concentration and BCFs with time in the three marine fishesduring; the 8-week hioconcentration experiment: O; TBT concentration: O, BCF. Bars indicate the standard deviation.

HISASH! YAMADAand KAZUFUMITAKAYANAGI

1592

8 0.3 Ca

JL (Exp. 8)

7

P. major

._~ 0.2

A Ca

J (Exp) ~

B

.~

6

5000 -~ m

f

ITI

1-

•

•~

o

;,

• .

ca

P. major

e-

¢D ~_ 0.t Q.

•

9

6

8

I

I

0.6

g o.,

o]

5000 ~

o

o

C (Exp. 9) R. ercodes

a. 0.3

e

(Control)

o.a

(Exp. 7)

0, O. 1

:,

.

,,~ •

(Control)

2 . 6 .

Experimental period (week) Fig. 3. Changes in the TPT concentration and BCFs with time in P. major and R. ercodes during the g-week bioconcenttation experiment: O, TPT concentration; Q, BCF. The TPT concentrations in the rearing seawater of (A), (B) and (C) in this figure were 63, 1650 and 148 ng/l, respectively. Bars indicate the standard deviation. seawater. These two fish species drink seawater at a rate of I-2ml/h/100g fish. If all of the TBT in the rearing seawater drunk by P. major was absorbed from the digestive tracts, the TBT concentration in the fish would be 0.13--0.26 ng/g during the 2-week period. Because the TBT concentration in the fish is more than 0.15/~g at the 2nd week [Fig. 2(A)], the possible TBT accumulation through the digestive tracts is negligible. Tachikawa and Sawamura (1988) reported similar results from their experiments on the bioconcentration of pentachlorophenol by Oryzea.v latipes (killifish). They estimated that only 0.2% of pentachlorophenol accumulated in the fish came from its absorption from the digestive tracts. Therefore, the accumulation of TBT in the fish body is due to its intake from seawater through the gills. Changes in the TPT concentration in P. major (Exp. 7 and 8) and R. ercodes (Exp. 9) are shown in Fig. 3. The TPT concentration increased to 0.197 _+0.011~ug/g in P. major reared in seawater containing 63 ng/I of TPT (Exp. 8), and increased to 5.44 +_0.15~ug/g in P. major reared in seawater containing 1650 ng/I of TPT during the 8-week period (Exp. 7). Comparing the two results for P. major [Fig. 3(A) and (B)], it is clear that the amount of TPT bioconcentrated in P. major depends on the TPT concentration in the rearing seawater. The TPT concentration in R. ercodes (Exp. 9) also increased from 0.025/zg/g at the beginning to 0.622 + 0.056/~g/g at the 8th week. Changes in the TPT concentrations in R. ercodes and P. major reared in seawater containing a large amount of TPT were small between the 6th and 8th weeks (Fig. 3). The TPT concentrations in these fish may have reached an equilibrium.

Elimination of TBT from fish Changes in the TBT concentrations in P. major, M. cephalus and R. ercodes for the elimination experiments are shown in Fig. 4. The TBT concentrations

in these fish decreased gradually with time. The TBT concentration in these fish were fitted to equation (2), G, = Cf, e-*2'. The correlation coefficients of the regression analysis were -0.68, - 0 . 7 4 and -0.94, respectively, indicating that they are highly significant. A slope of this regression line is considered as the elimination rate constant (k2), and is 0.024 d a y - ' for P. major, 0.052 day- i for M. cephalus and 0.078 or 0.094 day-~ for R. ercodes. The elimination rate constants and biological half-lives obtained in this study are tabulated in Table 2. The biological half-life of P. major was 28.8 days and longer than those of M. cephalus (I 3.4 days) and R. ercodes (7.4-8.9 days). These results indicate that P. major may not be able to excrete the absorbed TBT efficiently.

Bioconcentration factors of TBTO and TPTC The BCFs of TBTO and TPTC were calculated from equation (I) and summarized in Table 3 with previously published results for marine fish. Pagrus major and Chasmichthys gnathus (Shimizu and Kimura, 1987) can accumulate a large amount of TBTO. Their BCF was about 8000-10,000. On the contrary, M. cephalus and R. ercodes can only accumulate a small amount of TBTO. Their BCFs ranged between 2400 and 3600. Our study indicates that the BCF of TBTO for marine fish is larger than the previously reported BCFs for freshwater fish; C. carpio (Tsuda et al., 1988) and S. gairdneri (Martin et al., 1989). The BCF of TBTO for P. major is also larger than that for brackish water fish; C. variegatus reported by Ward et al. (1981), and is the largest among the fish species used in this study. BCFs, elimination rate constants and biological half-lives are listed in Table 2. The elimination rate constant (k2) of P. major with a large BCF was smaller than that of M. cephalus and R. ercodes with small BCFs (Table 2). Our results suggest that the BCF is related to the elimination rate constant. In other words, fish which are capable of excreting TBT

Bioconcentration and elimination of TBTO and TPTC in fish

1593

1000

1000

R. ercodes

P maior ¥

-

-0.024X + 5.824 (r = 0.79)

X =

100

-0.070X + 5.864 (r = 0.94)

~

A

.~

100

'

0

'

I

I

I

1

2

3

4

c

1000

10 1000

t

I

2

M cephalus

0

¥

-

-0.052X + 5.628 (r = 0.68)

Y =

i

I

0

I

! 2

10

~

R. ercodes

100

100

I

1

~

1

-0.094X + 5.816 (r I 0.97)

/

I

0

1

I 2

Elir~nation period (week)

Fig. 4. Changes in the TBT concentrations with time in the three marine fishes during the elimination experiment. compounds effectively do not accumulate a large amount of TBTO. It is well known that small fish can accumulate a larger amount of chemicals than larger fish (Murphy and Murphy, 1971). However, a clear difference in the BCF between large and small R. ercodes was not observed in this prcscnt study. The BCF for P. major reared in seawater containing 38ng/I of TBT (Exp. I) was larger than that reared in seawater containing 659ng/I of TBT (Exp. 2). These results suggest that the BCF of TBTO for marine fish depends on the TBT concentration in the rearing seawater. As shown in Table 3, the BCF of TPTC for P. major and R. ereodes is 3100-3300 and 4100, respectively. These BCFs for marine fish are larger than those for freshwater fish, C. carpio (Tsuda et al., 1987) and S. gairdneri (Tas et al., 1990), but these values are in the same order for P. reticulafa as those reported by Tas et al. (1990). For P. major, the BCF of TPTC was smaller than that of TBTO. Although R. ercodes does not accumulate TBTO as much as P. major does, the BCFs of TPTC for these fish are almost in the same order. Therefore, the metabolism of TPTC by R. ercodes may be different from that of TBTO. Rearing P. major in two different TPTC concentrations (Exps 7 and 8 in Table 3) resulted in

the same BCF. This implies that the bioconcentration of TPTC by the fish is independent of the TPT concentration in seawater. This phenomenon is different from thc bioconcentration of TBTO by P. major. Further studies arc necessary to clarify the metabolism of organotin compounds by marine fish. It is well known that a BCF is related to the octanol-water partition coefficient (Ko.) for many kinds of chemicals (Davies and Dobbs, 1984). BCFs of TBTO and TPTC can be estimated from the equation of Davies and Dobbs (1984) by using the log /to, values for TBTO (3.31) and TPTC (2.11). An estimated BCF of TBTO and TPTC is 146 and 28, respectively. The BCFs of TBTO and TPTC calculated in this study are significantly different from those estimated from Ko.. It is unclear whether this difference depends on the mechanism of their uptake and elimination by marine fish. This difference may also be due to the chemical speciation of TBT and TPT in the seawater. Further studies are necessary to explain the difference [x~twecn the calculated and estimated BCF. TBT and TPT concentrations in several tissues and organs of P. major Pugras major reared in seawatcr containing TBT and TPT for 8 weeks was divided into 7 portions:

Table 2. The BCF. elimination rate constant and biological half-life of TBT in three marine fishes

Species

Pagrusmajor Mugilcephalua Rudariuaer('ode.v

BCF

Elimination rate constant (k 2) (day t)

Biological half-life (fl : ) (day)

9400--I I000 2300-3000 3200-3600

0.024 0.052 0.078-0.094

28.8

13.4 7.4-8.9

HISASHIYAMADAand KAZUFUMITAKAYANAGI

1594

Table 3. The BCFs of TBTO and TPTC in marine fish Concentration Period Exp. No. (ng/I) (day1 BCF

Organotin compounds

Species

TBTO

Pagrus major

I

38

14

28

3 4 5 6

Mugil cephalus Rudarius ercodes

89 122 106

56

116 980 360 I00 1600

56 84 84 84 58

180-1000

117

1650 63

56 56 56

Chasmichthys gnathus

11O00__.3000 94OO+ IOO 2500 + 100

56 14 28 42 56 56 56

659

4800 _+1300 5200 ± 100 5000 + 300 2400 ± 200 3000 _+200 3600 3200 4- 400 2000-3000 3006-5000 8000-1 I000 Wholebody 2600 Muscle 1800 Head 2100 Entrails 4500 Muscle 1600 Entrails 3900 Liver 52000 3300 ± 80 3100 ± 200

C)'prinodon rariegatus

TP'rc

7 8 9

Pagrus ma]or Rudarius ercodes

148

head, liver, gill, digestive tracts (including adipose tissue around the digestive tract), muscle, skin and the residue (including kidney). The T B T and T P T concentrations against the lipid content in each tissue and organ are plotted in Fig. 5. The T P T concentration was highest in the liver, and d e c r e a ~ d in the order o f gill, digestive tracts, head, the residue, skin and muscle. On the contrary, the T B T concentration was highest in the skin and gill, and decreased in the order of liver, head, the residue, digestive tracts and muscle. The concentrations of T P T and T B T were lowest in the muscle a m o n g the tissues and organs examined. Larger amounts o f T P T C and T B T O were not accumulated in muscle. These results were consistent with the results o f Ward et al. (1981) and Tsuda et al. (1987, 1988). The difference in T P T concentrations in the tissues and organs was larger than that of TBT. The distribution pattern of T P T in P. m a j o r was also different from that o f TBT. These results suggest that the metabolic pathways and activities of these two organotin compounds are

This study This study This study This study Simizu and Kimura (1987) Ward et al. (1981)

This study This study This study

CONCLUSIONS

The BCF of TBTO for P. major, M. cephalus and R.

ercodes was

gl

9400-11,000,

2400-3000

0.5 2~5 0.4'

g

411)0± 400

This study

different, and that TBT might be easily adsorbed on the gills and skin directly in contact with the seawater. No apparent correlation was found between the T B T or T P T concentration and lipid content (Fig. 5). Trialkyltin compounds are known to bind to amino acids, peptides and proteins (Davies and Smith, 1980). indeed, the complexion bctwccn trialkyltin compounds and protein does occur at the - S H function site of protein as reported for methyimercury (Arima and U m c m o t o , 1976). This complexation between the trialkyltin compounds and protein may influence the tissue distribution of trialkyltin compounds. Therefore, the distribution of T B T and T P T in fish is different from the tissue distribution o f the hydrophobic chemicals such as polychlorinated biphenyls.

A O}

tO I-

This study

74O0_.*7OO

42

2

Reference

4100 _ 1200

el

0.3 cQ u

1

g 0.2

7e 1=0

p-

el

~ o.t '~0

t

!

30

,0

go

,o

20

30

40

50

Lipid content (%) Fig. 5. The relationships between the T B T or T I T concentration and lipid content in several tissues and organs of P. major, l, Head; 2, gill; 3, liver; 4, digestive tracts; 5, skin; 6, muscle; and 7, the residue.

and

Bioconcentration and elimination of TBTO and TPTC in fish 3200-3600, respectively. The BCF for P. major was the largest due mainly to its slow excretion of T B T from the body. The B C F of T B T O for the marine fish depended on the T B T concentration in the reared seawater. A larger B C F was obtained when the fish were reared in seawater containing a smaller amount o f TBT. The BCF o f T P T C for P. major and R. ercodes was 3100-3300 and 4100, respectively. The B C F of T P T C for P. major was independent o f the concentration of T P T in the rearing seawater. The BCFs o f T B T O and T P T C determined by the 8-week exposure experiment in the present study were larger than those estimated from Ko,. The accumulation of T B T O and T P T C in muscles was small compared to other tissues and organs of P. major, and the accumulation was not related with the lipid content in the tissues and organs examined. Acknowledgements--We are grateful to Dr Yoshihiro Satomi and Dr Kenji Tabata for their advice and critical readings of this paper. Thanks are also due to Mr Tadashi Endo and Mr Yoshikazu Kajigaya for their assistance in collecting the experimental fish.

REFERENCES

Alzieu C., Sanjuan J., Michel P., Borel M. and Dreno J. P. (1989) Monitoring and assessment of butyltins in Atlantic coastal waters. Mar. Pollut. Bull. 20, 22-26. Arima S. and Umemoto S. (1976) Mercury in aquatic organisms--ll. Mercury distribution in muscles of tunas and swordfish. Bull. ,lap. Soc. Sci. Fish. 42, 931-937. Barley G. E., Mann K. J., Brockbank C. I. and Maetz A. (1989a) Tributylin in Sydney Harbour and Georges River waters. Aust. J. Mar. Freshwat. Res. 40, 39-48. Barley G. E., Huhua C., Brockbank C. I. and Flegg K. J. (1989b) Accumulation of tributyltin by the Sydney Rock Oyster, Saccostrea commercialis. Aust. J. Mar. Freshwater. Res. 40, 49-54. Bligh E. G. and Dyer W. J. (1959) A rapid method of total lipid extraction and purification. Can. J. Biochem. Physiol. 37, 911-917. Blunden S. J. and Chapman A. (1986) Organotin compounds in the environment, in Organometallic Compounds in the Environment--Principles and Reactions (Edited by Craig P. J.), pp. I I 1-159. Longman, London. Bryan C. W., Gibbs P. E., Burt G. R. and Hummerstone L. G. 0987) The effect of tributyltin (TBT) accumulation on adult dog-whelk, Nucella lapillus: long-term field and laboratory experiments. J. Mar. Biol. Ass. U.K. 67, 525 -544. Champ M. A. and Pugh W. L. (1987)Tributyltin antifouling paints: introduction and overview, in Oceans 87. Organotin Symposium Proceedings, Vol. 4, pp. 1298-1308. Marine Technology Society, Washington, D.C. Cleary J. J. and Stebbing A. R. D. (1985) Organotin and total tin in coastal waters of Southwest England. Mar. Pollut. Bull. 16, 350-355.

1595

Clear,/J. J. and Stebbing A. R. D. (1987) Organotin in the surface microlayer and subsurface waters of Southwest England. Mar. Pollut. Bull. l& 238-246. Connell D. W. (1988) Bioaccumulation behavior of persistent organic chemicals with aquatic organisms. Ret,. era'it. Contam. Toxicol. 101, 117-154. Davies A. G. and Smith P. J. (1980) Recent advances in organotin chemistry. Adv. inorg. Chem. Radiochem. 23, 1-77. Davies R. P. and Dobbs A. J. (1984) The prediction of bioconcentration in fish. War. Res. lg, 1253-1262. Environment Agency of Japan (1989) Chemicals in the Em,ironment. pp. 432. EPA, Tokyo. Langston W. J., Butt G. R. and Mingjiang Z. (1987) Tin and organotin in water, sediments, and benthic organisms of Poole Harbour. Mar. Pollut. Bull. I& 634-639. Laughlin R. B. Jr and French W. (1988) Concentration dependence of bis(tributyltin)oxide accumulation in mussel, Mytilus edulis. Envir. Toxicol. Chem. 7, 1021-1026. Maetz J. (1970) Mechanisms of salt and water transfer across membranes in teleosts in relation to the aquatic environment. Mere. Soc. Endocr. 18, 3-29. Makkar N. S., Kronick A. T. and Cooney J. J. 0989) Butyltins in sediments from Boston Harbour, USA. Chemosphere 18, 2043-2050. Martin R. C., Dixon D. G., Maguire R. J., Hodson P. V. and Tkacz R. J. (1989) Acute toxicity, uptake, deputation and tissue distribution of tri-n-butyltin in rainbow trout, Salmo gairdneri. Aquat. Toxicol. 15, 37-52. Murphy P. G. and Murphy J. V. (1971) Correlation between respiration and direct uptake of DDT in mosquito fish (Gamhusia ajfinis). Bull. envir. Contain. Toxicol. 6, 581-588. Shimuzu A. and Kimura S. (1987) Effect of bis(tributyltin) oxide on gonadal development of salt-water goby, Chasmichthys dolichognathus: exposure during maturing period. Bull. Tokai Reg. Fish. Res. Lab. 123, 45-49. Tachikawa M. and Sawamura R. (1988) The accumulation and elimination of environmental chemical pollutants in fish. Jap. J. War. Pollut. Res. II, 681-685. Takami K., Okumura T., Yamasaki H. and Nakamoto M. (1988) Determination of triphenyltin and tributyltin compounds in fish and shellfish by capillary GC. BunsekiKagaku 37, 449-455. Tas J. W., Opperhuizen A. and Seinen W. (1990) Uptake and elimination kinetics of triphenyltin hydroxide by two fish species. Toxicol. Envir. Chem. 28, 129-141. Tsuda T., Nakanishi H., Aoki S. and Takebayashi J. (1987) Bioconcentration and metabolism of phenyltin chloride in carp. War. Res. 21, 949-953. Tsuda T., Nakanishi H., Aoki S. and Takebayashi J. (1988) Bioconcentration and metabolism of butyltin compounds in carp. Wat. Res. 22, 647-651. Wade T. L., Garcia-Romero B. and Brooks J. M. (1988) Tributyltin contamination in bivalves from United States coastal estuaries. Envir. Sci. Technol. 22, 1488-1493. Waldock M. J. and Thain J. E. (1983) Shell thickening in Crassostrea gigas: organotin antifouling or sediment induced? Mar. Pollut. Bull. 14, 411-415. Ward G. S., Gramm G. C., Parrish P. R., Trachman H. and Slesinger A. (1981) Bioaccumulation and chronic toxicity of bis(tributyltin)oxide (TBTO): test with a saltwater fish. Am. Test. Mater. Spec. Publ. 737, 183-200.