>preferring not to know.

I think this does have some ongoing influence on why more detailed analysis of common chemicals is not required.

From what I can tell, it looks like phthalates started with excess coal tar which contained tonnes of a solid waxy aromatic hydrocarbon called naphthalene that nobody probably had much of a way to monetize for quite some time.

Plenty of money was surely being made in other ways so regardless of the accounting methods, the surplus ends up being a no-cost item. When there are tonnes of an unutilized resource like this the full-scale effort would turn every tonne into something useful, and all it has to do is be the least bit useful and the least bit worth money for it look pretty good on paper. Plus the longer it builds up without having a good way to get rid of it can make a difference. Especially if one of the physical properties of the asset has something to do with combustibility and/or toxicity.

This gives extreme financial leverage compared to comparable chemical processes where a major raw material has a nominal cost, or even an attractive cost.

Anyway, naphthalene was an early source of cheap phthalic acids & anhydrides.

Also some oil fields have enough naphthalene content for it to be accumulated in the bigger refineries along with other waxy hydrocarbons which are processed in abundance.

Plus to meet increasing demand phthalic anhydride can also be made from ortho-xylene which many more refineries are commonly processing a stream of. This may not be zero-cost raw material, but it is still a hydrocarbon which is in bulk and easy to add value to if you're going to do something other than burn it for fuel.

In the 1980's the phthalate I would see the most of was "di-octyl phthalate", known as DOP. It was mostly di-(2-ethylhexyl) phthalate since the "octanol" that formed the diester was usually 2-ethylhexanol, not much n-octanol involved.

The 2-EH itself was some nasty-smelling stuff, one drop on your foot and you would have to leave your shoes outside when you got home. It was a byproduct of butanol & isobutanol manufacture, which themselves are relatively clean solvents. The 2-EH was clarified but it is a low-volatility solvent that doesn't dry up very fast, and stinks so bad it is not an ideal paint ingredient. There was no published laboratory testing procedure but I did do some pioneering chromatography anyway and there was a rich array of minor byproducts which are still most likely not fully identified chemically yet.

So 2-EH is another low-cost item but not much higher viscosity than the butanols.

Esterifying to combine with the phthalic and you get the compound DOP, the syrupy liquid used as a plasticizer that doesn't dry up much faster than the plastic solids themselves, and imparts the increased flexibility desired by the processor.

I wouldn't be surprised if there are some minor impurities in the DOP that trace back to the 2-EH raw material, which could be much more potent endocrine disruptors than the known plasticizer chemical itself. The statistical possibility is based on the number and variety of unidentified minor constituents, the way that very small amounts of hormones have very outsized effects, and the correlations that have been seen which incriminate the plasticizer and seem to show some connection.

Plus, after a few short years being a leading analyst of 2-EH and DOP, one day some highly purified 2-EH became available in "research grade", purchased it to serve as reference material, and it turned out to be relatively odor-free ! It was the 2-ethylhexyl aldehyde content that made it smell so bold. So I have known something was up for a very long time but still don't have all the details I would want.

Now if there is some minor component other than the known plasticizer bulk chemical itself which is causing disruption, and in-vivo work is being done on the highly purified reference material in order to evaluate the target plasticizer itself in the absence of as many unknowns as possible I'm not so sure the findings would apply as much in the real would as I would like.

At the beginning, phthalates were not optimized to serve as plasticizers.

They just happened to not fail at the task.

Got more popular, and non-surplus alternative sources of raw materials for plasticizing will break ground to meet the demand once the more-attractively-priced "chemical waste" has all been spoken for.

Something like a playbook that predates the plastic age.