>> pneumonia four times. i ain't never had no kind of problems. prior. >> four bouts of bronchial pneumonia. >> four times. >> reporter: two weeks ago a study analyzed the health effects of cleanup workers from the world's eight biggest oil spills. in one group of thousands of fishermen cleanup crews were twice as likely to have breathing problems than noncleanup workers, so what is it in oil that can make you sick if you breathe in too much of it? it turns out, there are over 200 chemicals in oil. some more dangerous than others. some in the form of particulate matter, tiny particles that can get into the lungs and cause serious breathing problems. dr. mike harp is an oncologist who sees gulf patients at his clinic. >> i think there is a fairly high likelihood that we'll see some increase in some cancers in some of the populations with the exposures to the chemicals. >> reporter: but most worry to these fishermen. >> anybody here suffering memory loss?