benzene , diphenyl sulfone ( dps ) , para - hydroxybiphenyl ( ppp ) , ortho - hydroxybiphenyl ( opp ) , higher hydroxybiphenyls , and alkylated benzenes were found in a small lake receiving contaminated groundwater discharge from the industri - plex superfund site ( woburn , ma ) in the aberjona watershed in eastern massachusetts . 
 all of these chemicals may derive from the former phenol manufacturing activities present at the industri - plex site during world war i. concentrations up to 1660 microgram / l benzene , 450 micro / l dps , 230 microgram / l ppp , and 100 microgram / l opp were detected in the hypolimnion . 
 epilimnetic concentrations of the chemicals were significantly lower ( normally < 5 
 microgram / l ) . 
 dps showed a distinct seasonal behavior : it was readily biodegradable during warm periods . 
 no biodegradation was observed in the winter , leaving export to the aberjona river as the major removal mechanism . 
 although benzene is known to be toxic and a human carcinogen , our results indicate that dps , opp , and ppp are not mutagenic in tests using human mcl-5 and h1a1v2 cell lines.imagesfigure 1