Passing the buck: The Trump EPA’s mind-boggling efforts to ignore the risks of 1,4-dioxane in drinking water

Richard Denison, Ph.D., is a Lead Senior Scientist.

Readers of this blog will recall the major concerns EDF, EPA’s science advisors, and many others have raised about the Trump EPA’s systematic exclusion from its risk evaluations of all human exposures to chemicals released to air, water and land.  EPA has taken this illegal, unscientific and un-health protective approach across the board in the risk evaluations it has issued to date in draft or final form under the Toxic Substances Control Act (TSCA).

EDF first flagged the emergence of this fatally flawed approach over two years ago, and again when it was applied to the likely human carcinogen 1,4-dioxane, one of the first 10 chemicals undergoing TSCA risk evaluations.  Since then the Trump EPA has doubled down, repeatedly defying its own science advisors who have called out this deficiency in virtually all of their peer reviews of EPA’s draft risk evaluations.  EPA is clearly refusing to budge, issuing two final risk evaluations for methylene chloride and 1-bromopropane that seek to codify the approach.[pullquote]EPA’s Office of Water is deferring any decision on whether to regulate 1,4-dioxane in drinking water, pending completion of a risk evaluation that expressly excludes that exposure.  That exclusion is in turn based on the TSCA office’s claim that the Office of Water already has it covered.[/pullquote]

The asserted basis for ignoring tens of millions of pounds of these chemicals released annually is EPA’s claim that the releases are adequately managed under other laws the agency administers.  To bolster that claim, EPA also asserts that it has closely consulted with the EPA offices that administer those other laws to ensure this is the case.  Let’s take a closer look at the nature – and apparent effects – of that consultation in one setting:  1,4-dioxane in drinking water, which falls under the authority of the Safe Drinking Water Act (SDWA) administered by EPA’s Office of Water. 

In its draft risk evaluation for 1,4-dioxane, EPA states (p. 156, emphases added):

EPA identified exposure pathways under other environmental statutes, administered by EPA, which adequately assess and effectively manage exposures and for which long-standing regulatory and analytical processes already exist, i.e., the Clean Air Act (CAA), the Safe Drinking Water Act (SDWA), the Clean Water Act (CWA) and the Resource Conservation and Recovery Act (RCRA). OCSPP works closely with the offices within EPA that administer and implement the regulatory programs under these statutes. In some cases, EPA has determined that chemicals present in various media pathways (i.e., air, water, land) fall under the jurisdiction of existing regulatory programs and associated analytical processes carried out under other EPA-administered statutes and have been assessed and effectively managed under those programs. …  Exposures to 1,4-dioxane to receptors (i.e., general population) may occur from industrial and/or commercial uses; industrial releases to air, water or land; and other conditions of use. As described above, other environmental statutes administered by EPA adequately assess and effectively manage these exposures. Therefore, EPA did not evaluate hazards or exposures to the general population in this risk evaluation, and there is no risk determination for the general population.

EPA’s invoking of the SDWA as resulting in 1,4-dioxane “hav[ing] been assessed and effectively managed” is exceedingly curious.

First note that recent monitoring by EPA found that 7% of public water systems nationwide serving more than 7 million Americans in 27 states were contaminated with 1,4-dioxane at levels exceeding the level EPA has found to increase the risk of cancer by one per million people, the level EPA generally aims to meet for general population exposures.  More than 280,000 pounds of the chemical were reported released to water in 2018.

There is no National Primary Drinking Water regulation for 1,4-dioxane; it is only included on the “Contaminant Candidate List” (CCL), which EPA itself describes as a list of unregulated contaminants.  Many more steps have to be taken to actually regulate a CCL chemical, which have not been taken for 1,4-dioxane.

Earlier this year, EPA had the opportunity to advance 1,4-dioxane along the path toward development of a limit for the chemical in drinking water.  It declined to do so.  This took the form of EPA declining to make a “preliminary regulatory determination” for the chemical when announcing its proposal to make such determinations for other chemicals also listed on the CCL.

Now, that decision by the Trump EPA may not be terribly surprising.  But what is interesting is why EPA declined.  Section V of its announcement states the following (p. 14,134; emphasis added):

The Agency is not making a preliminary determination for 1,4-dioxane at this time as the Agency has not determined whether there is a meaningful opportunity for public health risk reduction. The Agency intends to complete its new risk evaluation for 1,4-dioxane that is currently in draft (USEPA, 2019f) and consider it and the Canadian guideline technical document and other relevant new science prior to making a regulatory determination. This evaluation may provide clarity as to whether there is a meaningful opportunity for an NPDWR to reduce public health risk.

To be clear, the cited EPA document is none other than the TSCA office’s draft risk evaluation for 1,4-dioxane.  So, to sum up:  EPA’s Office of Water is deferring any decision on whether to advance 1,4-dioxane toward regulation in drinking water, pending completion of a risk evaluation that expressly excludes that exposure.  And that exclusion is based on the claim that the Office of Water already has it covered under the SDWA.

Is this what happens when the TSCA office “works closely with” another EPA office to decide whether to exclude an entire human exposure pathway?  The TSCA office not only gets cover to exclude the pathway from its TSCA risk evaluation.  It also convinces or conspires with the other office to defer or delay any regulation of the chemical – because the TSCA office is working on a risk evaluation that has no relevance to the other office because it excludes the very pathway of relevance.

All I can say is, wow.  Only the Trump EPA could bring you such a waiting-for-Godot moment.


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One Comment

  1. Tony Tweedale
    Posted September 3, 2020 at 5:13 pm | Permalink

    Yeah, it’s surreal! Still, EPA’s TSCA evaluation is a risk assessment (RA) and so estimated exposure paths have to be compared to the estimated safe dose; presumably both for “environmental” (ecologic) and for human risks.

    If EPA is not evaluating “[any] human exposures to chemicals released to air, water and land”, how is it concluding its RA?