The past shows that the EPA isn't to be trusted when it comes to Industrial
Chemicals…even (or especially) when it comes to pesticides and chlorine…and perhaps especially in so-called “tobacco” issues. Here's that story from one source:

The whole back and forth on this is at search pages for “Osteen EPA”.

Elsewhere we find that Judge Osteen, who shot down EPA's phoney hit on
“Environmental Tobacco Smoke”, was a confirmed anti-smoker. No matter about this decision—(which was later voided based on jurisdiction, not content, grounds) EPA garbage about “ETS” was and is still used to justify smoking bans.
(And OSHA's failure to find evidence against indoor “ETS” is rarely
mentioned….except by off-track “smoker's rights” groups. Other big studies that find no threat in “second hand smoke” are also ignored.)
In this fracking case, and in that “smoking” deal, the EPA is caught
protecting the interests of Big Industrial Chemicals.
In the cig case, yeah, it looked like the EPA was hot on the tail of evil “Big
Tobacco”…but the EPA was actually protecting them from the astronomical potential liabilities linked to the pesticides, chlorine-dioxin, and other deadly non-tobacco cigarette components. Chlorine and pesticide etc interests let off the hook too.

This is Very Hard to research because the issue has been reduced to
pro-smoking and anti-smoking. forces. Thorough research, that includes
acknowledgement of the non-tobacco cig contaminants is NOT TO BE FOUND. You can go to “conservative” sites that hate the EPA no matter what, or to “smoker's rights” sites (that ignore smoker's rights to know what they're smoking, to be free of industrial chem poisoning, or to have rights to compensation for being guinea-pigged and endangered) and you get nowhere. (Proving you got your cancers from cigarette pesticides, rads and dioxins…and not from somewhere else…is next to impossible, I hear.)

PS: What's really funny are those who list “chemicals” to scare people from smoking tobacco. They list DDT, formaldehyde, arsenic, vinyl chloride, and a bunch of other chems, and PO-210 radiation, that are NOT parts of tobacco but ARE dangerous industrial goodies that the EPA, FDA and the rest still ALLOW in cigs, without testing and without warning to consumers. DDT has been banned for use in the USA for… what… decades. It's in US cigs because, back in 2003 or so, US Customs and Dept of Ag, incredibly, STOPPED checking import tobacco for DDT and other toxins banned in the US. That was just a year after the GAO condemned lax govt oversight of pesticide residues on tobacco.
Sadly, and inexplicably, even anti-pesticides activists fail to note that
there are MANY pesticide residues in typical cigarettes. Indeed, a lot of
evidence against pesticide use is being lost as so many harms are allowed to be blamed on just the tobacco plant.