1,4-Dioxane: EPA Draft Risk Evaluation and New Developments

One of the most significant regulatory challenges associated with 1,4-Dioxane for U.S. business relates to groundwater cleanup standards and how to remediate existing groundwater contamination. EPA’s recent risk assessment work will have little or no impact on this important environmental consideration at least in the short term.

On July 1, 2019 EPA published notice of its draft risk evaluation for 1,4-Dioxane and the opening of the public comment period until August 30, 2019. EPA’s regulatory docket confirms that to date 10 environmental groups and trade associations have commented on the draft evaluation and proposed 1,4-Dioxane findings. EPA looked at 14 conditions of 1,4-Dioxane use associated with manufacturing, processing, distribution, use and disposal. EPA made 3 initial risk determinations: 1) No unreasonable risk to occupational non-users; 2) unreasonable risks to workers in certain circumstances; and 3) no unreasonable risk to the environment. EPA concluded that existing federal environmental laws already adequately assess and manage risks from 1,4-Dioxane, except in situations where workers face risks of cancer from chronic dermal occupational exposure and non-cancer risk resulting from chronic inhalation.

1,4-Dioxane is used primarily as a solvent in industrial and commercial processes such as the manufacture of other chemicals, as a processing aid and laboratory chemical reagent, or in adhesives and sealants. Historically, 90% of 1,4-Dioxane production was used as a stabilizer in chlorinated solvents such as 1,1,1-trichloroethane (TCA). Primarily as a result of its TCA connection, increasingly 1,4-Dioxane is identified as a contaminant of concern in soil and groundwater cleanup actions.

EPA’s risk assessment efforts, including the draft evaluation, provide no clear mandate or meaningful guidance on how to proceed with cleanup standards applicable to 1,4-Dioxane and as a result, states are taking action on a state-by-state basis. While some states have taken a wait and see approach on 1,4-Dioxane, others have established cleanup standards that range from 0.35 ug/L to 77 ug/L. EPA’s failure to develop a maximum contaminant level (mcl), coupled with the lack of efficient, cost effective in situ remedial alternatives, present substantial regulatory burdens for businesses managing voluntary, private party, state-led or Superfund site cleanups.

Perhaps the draft 1,4-Dioxane evaluation is one step closer to regulatory consensus on risk posed by this chemical but any progress on the development of a risk-based cleanup standard by EPA remains uncertain.


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