1,4-Dioxane Chemistry, Uses, and Occurrence - Environmental Investigation and Remediation - page 102

above 10 g/L; the highest detections ranged from 50 to 95 ppb (Abe, 1999). All of the seven sam-

pling stations in the three rivers had 1,4-dioxane detections in each of i ve sampling events. Three
river sampling stations had all i ve analyses falling in the range 0.1-0.99 ppb; three fell in the range
0.2-3.3 ppb, and one river sampling station fell in the range 2-16 ppb (Abe, 1999). Sources of
1,4-dioxane were attributed to legacy contamination by methyl chloroform and industrial and domes-
tic wastewater discharges.
1,4-Dioxane has been detected in ambient air monitoring samples in a few isolated studies. USEPA
compiled 1,4-dioxane measurements of ambient air performed at 45 locations in 12 cities taken between
1979 and 1984. The results indicated concentrations ranging from below detection limits to 30

μ

μ g/m 3 .

g/m 3 (0.12 ppbv) (USEPA, 1993). Air sam-
ples in industrial areas in Newark, Elisabeth, and Camden, New Jersey, were collected from July 6 to
August 16, 1981. The geometric mean 1,4-dioxane concentrations ranged from 0.01 to 0.02 ppbv (0.04
to 0.07

The mean ambient concentration of 1,4-dioxane was 0.44 μ

g/m 3 ). 1,4-Dioxane was detected in 51% of the samples (Harkov et al., 1981).
Washington State's Northwest Air Pollution Authority (NWAPA) performed a study of ambient
concentrations of hazardous air pollutants at i ve different sampling locations in Bellingham,
Washington (north of Seattle), on 107 sampling days between July 1995 and August 1999. Data qual-
ity in this study was compromised: detection of 1,4-dioxane in control blanks left some of the results
unusable. 1,4-Dioxane was detected above reporting limits at all i ve sites. The geometric mean of all
samples at each site, including suspect values, was about 5

μ

g/m 3 at
a third site. No known major emission sources are present in the area (Keel and Franzmann, 2000).
In the 1980s, USEPA compiled a National Ambient Air Database of indoor and outdoor mea-
surements of 320 VOCs. The database includes 585 analyses for 1,4-dioxane, for which the average
concentration was 1.03 ppbv; 75% of measured values were less than 0.09 ppbv, and more than half
showed no detection (Shah and Singh, 1988).

μ g/m 3 at two sites and about 10 μ

EXTR ATERRESTRIAL FORMATION OF 1,4 -DIOXANE?

1,4-Dioxane may be among the organic compounds found in trapped volatiles in carbonaceous
chondrites from meteorites formed in the solar nebula (Studier et al., 1965). A NASA study
investigated the production of aliphatic and aromatic hydrocarbons from reactions between
carbon monoxide and hydrogen, the principal components of cosmic gas, catalyzed by iron
and stony meteorites at temperatures between 25°C and 580°C. Experiments involved expos-
ing Canyon Diablo powder (a ground iron meteorite) to a 1:1 mixture of carbon monoxide and
hydrogen. After 4 h and 20 min at 115°C, mass spectral peaks at 88 and 58 m / z were observed,
which indicated formation of 1,4-dioxane (Studier et al., 1965).

2.8 ESTIMATED RELEASES OF 1,4-DIOXANE TO THE ENVIRONMENT
The amount of 1,4-dioxane released to the environment since 1988 can be estimated by tracking the
quantity of 1,4-dioxane reported in USEPA's TRI database. 1,4-Dioxane is reportable in waste
streams at concentrations above 0.1% because it is listed by the Occupational Safety and Health
Administration as a probable carcinogen, based on reports from the National Toxicology Program
and the International Agency for Research on Cancer. For each year, the TRI database presents data
compiled from hundreds of thousands of reports from hazardous waste generators; the data are
categorized into a variety of sectors of treatment and disposal. It is not surprising that the data avail-
able from USEPA's TRI database, particularly in the i rst few years of TRI data collection and
reporting, are sometimes imprecise, given the monumental scope of the task. The TRI data sets
are nonetheless useful for providing the approximate quantities, locations, and i nal disposition of
1,4-dioxane releases.