Our studies are concerned particularly with energy-related 
organic contaminants that are potentially mutagenic or carcino¬ 
genic. Many such compounds are present in the water-soluble 
fraction of fuel oils and are rapidly accumulated by aquatic 
organisms. 
Aromatic amines represent a class of organic contaminants 
that are present in a variety of industrial and energy-related 
wastes. The biological hazard posed by these compounds is 
largely determined by their biotransformation; that is a 
specific metabolic reaction (N-hydroxylation) is required before 
they elicit mutagenic or carcinogenic effects. Unfortunately, 
little is known about the ability of aquatic organisms to 
metabolize these contaminants. In our studies we have developed 
experimental protocols that can be used to assess the in vivo 
metabolic processing of these and other organic contaminants by 
marine invertebrates. Such basic information is needed because 
our knowledge of chemical metabolism has been based largely on 
studies of vertebrate organisms and may not directly apply to 
invertebrate species. With increased understanding of biotrans¬ 
formation in marine mussels, we will be better able to predict 
the effects of organic contaminants found in contaminated 
ecosystems. 
For our experiments we chose to study the metabolic trans¬ 
formation of a model aromatic amine (o-toluidine) whose struc¬ 
ture is representative of a broad class of potentially mutagenic 
contaminants. The mussels that we used in our initial experi¬ 
ments were from Tomales Bay. These mussels rapidly accumulated 
o-toluidine and eliminated metabolites that were significantly 
different from those produced by vertebrate organisms (Figure 
1). Mussels and vertebrate organisms form different metabolites 
because they have different detoxification mechanisms. In addi¬ 
tion to producing mutagenically activated (nitrogen-oxidized) 
metabolities, the mussels were able to add a single carbon atom 
to the nitrogen atom and form a novel detoxification product, 
n-formyl-o-toluidine. This nitrogen metabolizing pathway repre¬ 
sents a significant departure from the two-carbon addition (ace¬ 
tylation) that is usually observed in vertebrate of this common 
detoxification pathway. The common carbon-oxidizing metabolic 
pathways that we expect to occur in mammals were not found in 
the mussels? we did verify our experimental techniques by 
isolating these metabolites from a rat injected with o-toluidine 
(Figure 6). 
The pathways available to mussels for the metabolism of 
aromatic amines consist of reactions that the organisms normally 
utilize for the metabolism of amino acids, fatty acids, and 
proteins. Any change in the organism's ability to metabolize a 
foreign compound (i.e., o-toluidine) should therefore be 
indicative of its overall physiological state. We investigated 
this hypothesis by measuring the metabolic capabilities of 
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