A study of the hepatic microsomal epoxide hydrolase in sea birds.

1. Epoxide hydrolase activities were measured in six species of sea birds using the chlorinated epoxide HEOM as substrate. 2. The activities found fell within the general range for birds, and there were no clear sex or species differences. 3. Relatively low activities were found in liver microsomes of female puffins early in the breeding season, but high activities were found in 11,000 g precipitates from these individuals. Apart from this no correlations were found between activity and time of year, PCB residues or geographical location. 4. These results are discussed in relation to mono-oxygenase activities in the same samples.