TPH is not regulated by the Feds. Individual states have monitored TPH by establishing cleanup levels. Levels beyond which contamination is not permissible. Dramatic variations: 10ppm to 10 000ppm, depending on state, land use, proximity to human habitation.
Addressing this great disparity. By standardizing the science, reduce disparities among the states. Transformation << measuring gross value >> assessing the risk to human health that groups of hydrocarbons might make.
"It used to be that we would ask how much of the contamination do we need to clean up? And now we ask how much do we need to clean up to make the area safe for humans?"
Insight into the capacity to (de)materialize toxins.
Carbon and hydrogen: aliphatic and aromatic; methane ethane propane; benzene toluene napthalene
aliphatic are chained carbon bonds
aromatics are rings
configuration of dislocation of valence electrons >> stability of ring compound
ring structure solidifies the compound >> stronger than is mathematically anticipated
>> greater thermodynamic force; clearly detrimental to any lifeform
structure <> toxicity
Classification of compounds into groupings or fractions: break down thousands of compounds into fractions, classes, groupings of hydrocarbons
>> proclivity of hydrocarbon to be volatile
minimal risk levels had been determined for some fractions << inhalation or skin contact
but crude contains thousands of hydrocarbons
some of these consist of hundreds of carbon atoms--only 250 had been identified by 2009; only 25 had been studied enough to determine their toxicity
those contained only a dozen or so carbon atoms