1,4-Dioxane Chemistry, Uses, and Occurrence - Environmental Investigation and Remediation - page 86

Methyl chloroform was the favored solvent for alkyd resin coatings and for cleaning paint and coat-
ing spray guns and l uid hoses (USEPA, 1997b).
Methyl chloroform and dichloromethane could contribute 1,4-dioxane to paint compositions
in minor amounts when 1,4-dioxane is present as a stabilizer. 1,4-Dioxane has been documented as
a trace ingredient in paints that used methyl chloroform as a drying solvent. For example, polyurethane
coatings contained less than 1% 1,4-dioxane (Glidden Paint, 1992). Resin formulations used large
amounts of solvents to facilitate application and drying. A polyamide resin formula included 70%
methyl chloroform with less than 5% 1,4-dioxane (DeSoto, Inc., 1991). Some lacquer formulations
contained only 8% solids; the balance was composed of solvents and thickeners, including as much as
60% 1,4-dioxane (American Cyanamid, 1987). Pervo Paint Company (1993) stated that white trafi c
paints for striping lanes contained as much as 24% methyl chloroform and 0.5% 1,4-dioxane; yellow
and red trafi c paints had less than 0.1% 1,4-dioxane. However, according to the USEPA Toxic Release
Inventory database, Pervo Paint Company removed 1,4-dioxane from its products in 1994.
“Dioxane purple” is a color name for an acrylic paint used by hobbyists and artists. 1,4-Dioxane
has been found in the low part per million range in European felt tip pen inks and fabric dyes
(Hansen, 2005). Mixtures of cyclohexanone with 1,4-dioxane or tetrahydrofuran and 1,4-dioxane
are preferred for painting the primer layer on magnetic tapes; the outer magnetic layer is applied by
using xylene and toluene. 1,4-Dioxane comprises about 10% of the magnetic tape paint mix (Roller
et al., 1977). Magnetic tape producers have historically discharged 1,4-dioxane in wastewater.
The dominant paint-removal solvent is dichloromethane, which in some instances includes
1,4-dioxane as a stabilizer. The most common paint-stripper formulation contains 60-65% dichloro-
methane. This solvent is particularly effective at penetrating the coating and causing it to swell and
separate from the substrate (USEPA, 1996a). In 1989, more than 100 million pounds of dichlo-
romethane was used for paint stripping, which was about a quarter of all dichloromethane produced
in that year. About 40% of dichloromethane applied for paint stripping was used in the maintenance
sector for stripping aircraft and other large vehicles and parts (SRRP, 1991). Because paint stripping
often includes a pressure-washing step following treatment with the paint-stripping solvent, water
may become contaminated with dichloromethane. USEPA estimates that the discharge of dichlo-
romethane to water from paint-stripping operations in 1989 exceeded 8 million pounds (SRRP,
1991). Several citations in publications focusing on toxicology, risk, or summary fact sheets for
1,4-dioxane have listed 1,4-dioxane as a solvent used directly for paint stripping; however, none of
the sources checked corroborated this assertion.
2.3.5 F LAME R ETARDANT P RODUCTION
1,4-Dioxane is used as a solvent in the production of brominated i re retardants. These are produced
by reacting cyclododecatriene with bromide in the presence of a solvent, generally an alcohol such
as isobutanol or 1,4-dioxane. 1,4-Dioxane is favored over alcohol because alcohol causes reaction
intermediates to precipitate out of solution before they can be completely reacted and because alco-
hols directly consume the brominating agent. Using 1,4-dioxane eliminates the problem of interme-
diates remaining at the end of the reaction, and 1,4-dioxane does not react with the brominating
agent (Business Communications Company, 2002). Waste 1,4-dioxane is recovered for off-site use
as a fuel (USEPA, 2006).
2.3.6 R UBBER AND P LASTICS I NDUSTRY
The USEPA's surveys of chemical releases in different industries, known as Sector Notebooks,
group the rubber and plastics industries together. The Rubber and Plastics Industry Sector Notebook
lists 1,4-dioxane as a waste emitted from four facilities out of more than 400 surveyed; however, the
Toxics Release Inventory data cited are probably inconsistent in reporting 1,4-dioxane if it was not
directly used. The Toxics Release Inventory data cited for 1993 include about 200 facilities releasing