wk in 2,000-liter tanks. Fish were not in spawning 

 condition. 



In each of two separate studies, 10 fish were 

 placed into each of six 660-liter fiber glass tanks 

 and further acclimated for 1 wk before exposure. 

 Salinity and temperature were 24%o and 9°-ll°C, 

 respectively, during the acclimation and test 

 periods. In the first study, fish were exposed to 100 

 nl/liter (ppb) 14 C benzene (4.2 dpm/ng specific ac- 

 tivity). In the second study, fish were exposed to 

 100 nl/liter (ppb) 14 C toluene (3.2 dpm/ng specific 

 activity). In both studies, one of the six tanks was a 

 control, with no exposure. Exposures were static 

 (single dose with delining concentration) for 48 h, 

 preceded and followed by a continuous water flow 

 of 2 liters/min. 



Water samples for radiometric aromatic anal- 

 yses were taken from all tanks at 0, 6, 24, and 48 h 

 after initial dosage. Gallbladder, intestine, pyloric 

 caeca, gill, brain, liver, muscle, kidney, and imma- 

 ture male and female gonad tissues were sampled 

 for radiometric analyses at 6 h, then daily for 7 

 days. 



Methods of exposure and radiometric analyses 

 are identical to Korn et al. (1976), except that the 

 tissues from fish exposed to toluene were digested 

 at 50°C for 24 h. 



Since accumulation levels in the gallbladder 

 were based solely on radiometric analysis of the 

 14 C present and could include metabolites of the 

 monoaromatics as well as unchanged benzene or 

 toluene, an additional study was made to interpret 

 the residue. Two groups of fish, with six fish per 

 tank, were exposed to 100 nl/liter 14 C benzene (1 

 tank), and 100 nl/liter 14 C toluene (1 tank) for 48 

 h. Exposure was the same as in the above experi- 

 ments. At the end of the 2-day exposure, the gall 

 bladders were removed, weighed, and extracted 

 with 0.2 ml trifluorotrichloroethane-Freon. 1 The 

 extracts were analyzed for benzene and toluene by 

 gas chromatography (Benville and Korn 1974). 

 Efficiency of extraction was not determined and 

 therefore the gas chromatography analyses were 

 more qualitative than quantitative. 



Results and Discussion 



There were no mortalities in either exposed or 

 control fish. Unlike herring exposed during 

 spawning condition (Struhsaker 1977), no abnor- 



mal behavior was noted, thus immature herring 

 appear less sensitive to exposures than mature 

 herring in spawning condition. 



The concentration of benzene and toluene in 

 seawater in all tanks declined linearly (Y — a + 

 bX where Y = concentration in microliters per 

 liter, a = initial concentration in microliters per 

 liter, b = rate of decline in microliter per liter per 

 hour, and X = time in hours), during the 48-h 

 static exposure, as follows: 



Item 

 Total no. samples 

 a (Y-intercept) 

 b 

 Percentage of initial 



concentration remaining: 

 24 h 

 48 h 



Benzene 



20 

 0.094997 

 0.0006075 



85 

 69 



Toluene 



20 

 0.09195 

 0.0007587 



80 

 60 



'Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



The equation for decline in benzene and toluene is 

 probably a function of the volume of seawater. In 

 earlier studies, at smaller volumes, decline was 

 exponential over the 48-h static exposure. At the 

 volume in these experiments it was linear, but 

 probably would have been exponential over a 

 longer time period. The rate of decline appears to 

 decrease with increasing volume. 



In all herring tissues, toluene accumulated to 

 higher levels than did benzene (Table 1), despite 

 the faster loss of toluene compared with benzene 

 from the test solution. Certain trends were com- 

 mon to both aromatic components. The tissue 

 exhibiting the highest accumulation was the 

 gallbladder (3.1 nl/g benzene, 34 nl/g toluene, 

 maximum level). The lowest level of maximum 

 accumulation was found in the immature gonad 

 (0.24 nl/g benzene, 0.44 nl/g toluene). Pyloric 

 caeca and intestine contained varying amounts of 

 bile and therefore had a wide range of 14 C activity 

 and a resulting wide variance in calculated con- 

 centrations. 



Benzene was accumulated up to 31 times the 

 initial water concentration (gallbladder) and tol- 

 uene reached 340 times the initial water concen- 

 tration (gallbladder). 



In most tissues, and for most components, 

 maximum accumulation levels were reached 

 rapidly. Within 24 h, maximum residues were ob- 

 tained in all tissues except the gallbladder and 

 pyloric caeca. Toluene accumulated to the 

 maximum level (0.25 days) before benzene peaked 

 ( 1-2 days) in all tissues except the gallbladder and 

 intestine. 



634 



