Regulatory Policy Implications of 1,4-Dioxane - Environmental Investigation and Remediation - page 472

3. Developing improvements to ISCO technology that can be safely and economically
deployed to remediate 1,4-dioxane source zones
4. Developing analytical methods that can reliably detect the expected biodegradation and
reaction breakdown products of 1,4-dioxane at trace levels
10.5 BLINDSIDED AGAIN?
Groundwater scientists must face the inevitable question about the appearance of 1,4-dioxane at so
many solvent release sites years after adopting cleanup plans to address solvent contamination:
“How could this have happened?” Have we routinely examined the full gamut of contaminants in
solvent degreasing wastes and dismissed them from the list of contaminants of concern? Or have we
neglected to consider what it is we are cleaning up? Site characterization must include analysis of
the source waste itself wherever available for sampling, or investigations should leverage GC/MS
analysis to perform open-scan searches for TICs in source-zone samples, lest we be blindsided
again by surprise contaminants like 1,4-dioxane (Mohr and Crowley, 2001).
When should we have known? * Did we miss the signs? There have certainly been a few signs
available to show that 1,4-dioxane was potentially harmful and that it was a very mobile contami-
nant. Moreover, some in the community of groundwater professionals, particularly regulatory staff
in USEPA, California DTSC, water boards, and probably water quality staff in other states, recog-
nized that 1,4-dioxane poses a signii cant problem and took action to investigate. At different points
in time, there have been pockets of awareness, but apparently, that awareness was not sufi ciently
extensive to cause regulators and consultants to pursue 1,4-dioxane universally at solvent cleanup
sites. When individual regulators realized the potential for 1,4-dioxane to be a signii cant ground-
water contaminant, they were probably challenged to i nd the time or authorization to pursue the
issue in addition to their already large caseloads. Awareness has grown substantially in the begin-
ning of the new millennium, as measured by thousands of downloads of the Solvent Stabilizers
White Paper (Mohr, 2001) since its presentation to the Groundwater Resources Association of
California in 2001. Some signs of the potential hazard to water resources posed by 1,4-dioxane and
other solvent stabilizers were available to industry and to water quality professionals through the
past several decades, as summarized in Table 10.1 .
A review of the toxicology literature in Chapter 5 shows that since 1,4-dioxane was patented
as a metal inhibitor for Dow Chemical's grades of methyl chloroform in 1957, there have been
publications on 1,4-dioxane toxicity or carcinogenicity in nearly every decade. Even so, does the
above list of sources of information mean that we should have known and prioritized investiga-
tion of 1,4-dioxane releases sooner? The sources of information in Table 10.1 reside in disparate
corners of the various professions whose expertise is invoked to protect groundwater quality.
Moreover, although these information sources were all available in the pre-Google decades, it
would have been rather difi cult for individuals and institutions to assimilate all of this scattered
information and draw a conclusion to prioritize 1,4-dioxane. The possible exceptions include the
USEPA, which is charged with identifying environmental threats and whose libraries house much
of the needed information, and Dow Chemical or other producers of 1,4-dioxane and 1,4-diox-
ane-stabilized methyl chloroform, whose research chemists evaluate the potential environmental
hazards of their products.
A broader question is whether the community of groundwater professionals should have realized
the hazards posed by the widespread use and routine disposal of chlorinated solvents to facilities we
now know were ill suited to contain them. The answer is, debatably, “yes”: Analytical methods to
detect chlorinated solvents in groundwater at the concentrations found near source zones were well
* The collective “we” refers to the community of groundwater professionals and scientists, whether employed by regulatory
agencies, industry, consulting i rms, universities, or water districts.