and lo anad bebehold, most of them we looked at showed us a change that would suggest they had been exposed to some chemical. so now the question is, can there b be bad effects as a result of the exposure? for many kinds of chemicals, when they are taken into the body, the body has a way of reacting, and that reaction is by making more of the enzyme that will metabolize those chemicals. it happens lalargely as a way for the organism to protect itself. this enzyme is the principle one that is produced in response to exposure to oil. with an enzyme like this, things move in and out. here the change would take place, and that change can be carcinogenic. the irony is that in the transformation of something like benzoapyrene, bicep 1a is referred to as a double edge sword. it cuts two ways. one is protection and the other is damage that can result from the metabolites produced. [birds squawking] joanna: what's really becoming clear to scientists is that therere's no place in n the word nonow that is pristine b because we're puttiting in every day toxins and oil and other pollutants into the wate