Until recently space travel has been something governmental entities take on. With commercial companies entering the foray, what liabilities are they accountable for in regards to the crap they leave behind? Does the EPA's influence reach out into space? Who regulates "Space Safety"?
There has been a starting point for international law in place since the 1967 Outer Space Treaty and specifically the detail given in the 1972 Convention on International Liability for Damage Caused by Space Objects.
This is an lay-persons and engineering risk perspective and I am not licensed to give legal advice! To this extent the convention asserts that the "launching state" is responsible for liabilities, assessed on a fault basis. Also, its present interpretation is that state signatories are liable for the actions of their citizens and corporations and are expected to regulate accordingly.
Note in particular that whilst "Until recently space travel has been something governmental entities take on." may have been intended to refer to crewed flight it is not correct in the liability sense. Commercial space operations and launches have existed since the 1960's and '70s respectively and the largest commercial satellite operators control many tens of satellites each. As context to the commercial interest that exists the privately sponsored Space Data Association was created in 2009 by Inmarsat, Intelsat and SES to share data to assist in collision avoidance and radio frequency problems.
The liability convention still gives rise to imponderables about which party bears liability. In the case of a satellite operator from state A, procuring a satellite from a manufacturer in state B which is then placed on a launch vehicle built in state C but launched from state D then each of those countries can be liable for third party losses.
As for national regulation, many countries have had something in place for decades. I'm less familiar with the US practice though I understand, rather than the EPA, that three bodies, the FAA, NOAA and the FCC participate in the regulatory activity.
@jvriesem is right that asymmetries have arisen between countries in terms of how they implement their own regulations. If you keep your eyes open you may see corporations lobbying their own governments on the basis that they believe their local laws are stricter than elsewhere and there have been unilateral moves to harmonise matters. Furthermore, I suspect that "flag of convenience" filing of satellite assets under shell companies set up in diverse regimes may well already occur though it might be hard to trace as to whether it was motivated by lighter regulations.
Nobody regulates space debris yet. It's a new frontier for all of us, and as such, nobody has claimed any "rights" to the airspace or established binding rules regarding its use. Besides, if one government passed regulations regarding space junk, other governments wouldn't necessarily be bound to follow those regulations. As such, the EPA could set the strictest rules for US space vehicles, but a Russian satellite company wouldn't be bound by those rules at all.
That said, NASA has a program (the Orbital Debris Program) dedicated to monitoring space debris and has established its own standards to help minimize space debris generation. As far as I know, this is the world's premiere space debris program. :-)