The heavy PAH's are supposed to pose no risk to human health
But aging of crude reduces acute toxicity; the aromatics with a greater molecular structure are toxic increasingly relative to the number of carbon rings
It was thought they were not biologically available
but after Exxon Valdez << decline in fishing population there were new studies
many multi ringed compounds >> long term negative effects because they do become biologically available
3 to 5 ring PAH's metabolize as plastogens: they rearrange sections of chromosomes
so more rings are not more benign...
chronic long term sublethal effects increase with time not diminish, especially with heavier ones
scientists: complexity of these hydrocarbons
the metabolites of distinct PAH's depend on the organ, development, size, etc. Very interactive
multi ringed compounds >> questioning protection of scientific knowledge
cf tobacco industry
petroleum industry not innocent here: 1775 chemicals in fossil fuels and cancer link!
1930s hydrocarbons <> leukaemia
50 years of manufacturing uncertainty to stall regulation
>> production of constrained certainty
to foreclose the need for further research
insistence on the heavy rings' inertia
>> demonstrated that crude TPH level of 67 000ppm not deleterious...
>> reduce need to analyze sites