Environmental Engineering Reference
In-Depth Information
10 Regulatory Policy Implications
of 1,4-Dioxane
Thomas K.G. Mohr
The growing number of groundwater contamination sites where 1,4-dioxane is present leads to
several important policy questions on the regulation of 1,4-dioxane in drinking water and at cleanup
sites, as the preceding chapters demonstrate. Foremost among these questions is whether other
states and the federal government should follow the lead set by the CDPHE and establish regulatory
standards for 1,4-dioxane. The question of setting standards depends on the ongoing debate about
1,4-dioxane's toxicity, which centers on the nonlinear dose-response for 1,4-dioxane's toxicity and
carcinogenicity endpoints. Do the toxicological assays of 1,4-dioxane adequately determine carci-
nogenicity? In the face of toxicological uncertainty, should we apply the precautionary principle and
regulate 1,4-dioxane in case it is later coni rmed to be a human carcinogen? Or should we be cau-
tious about committing scarce i nancial resources to remediate contamination whose potential to
cause harm is still being evaluated? Among the criteria used to set drinking water standards is the
estimated population exposed to 1,4-dioxane in drinking water, which requires solid data for
1,4-dioxane occurrence in public drinking water systems. This in turn leads to questions on the
policies applied by federal and state agencies to administer drinking water testing requirements that
best serve the public for emerging contaminants such as 1,4-dioxane. When water utilities discover
1,4-dioxane in drinking water systems, they face the difi cult challenge of risk communication, that
is to inform their customers while preserving their reputation for reliably serving high-quality water
and protecting their legal interests.
At sites contaminated with chlorinated solvents, the late discovery of 1,4-dioxane poses a
number of regulatory policy questions. Should the regulator reopen the Record of Decision or other
regulatory order to add cleanup goals for 1,4-dioxane? Does the presence of 1,4-dioxane, a recalci-
trant and mobile contaminant, negate the premise for previously approved chlorinated solvents
cleanup plans that employ monitored natural attenuation (MNA)? Without successful methods for
in situ remediation of 1,4-dioxane, pumping and ex situ treatment or in-well treatment are the
primary options. Do the benei ts of removing 1,4-dioxane from contaminated groundwater via
high-volume pumping outweigh the environmental impacts of energy consumption and associated
greenhouse gas emissions?
Finally, 1,4-dioxane is subject to some of the same regulatory policies as other chemicals put into
widespread use to solve one problem while unintentionally causing another. The fuel oxygenate
MTBE * is a prime example, perchlorate in road l ares is another. When should the community of
university and research scientists, consulting and industry professionals, and water resources man-
agers have known that 1,4-dioxane would cause widespread groundwater contamination? Did we
miss the signs or are we now applying 20-20 hindsight? Why do we i nd ourselves, once again,
“blindsided”? The European Green Chemistry program, REACH (Registration, Evaluation &
Authorization of Chemicals), is intended to prevent the widespread deployment of environmentally
harmful chemicals. Can regulations succeed in preventing the next 1,4-dioxane-like contaminant
from damaging irreplaceable groundwater resources?
* MTBE is methyl tert -butyl ether, the fuel oxygenate.
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