1,4-Dioxane Chemistry, Uses, and Occurrence - Environmental Investigation and Remediation - page 85

in iodized salt (Saifer and Hughes, 1937). Its use for other iodide analysis methods dates back to
1926 (Anschutz and Broeker, 1926).
2.3.4 P RINTING I NKS AND P AINTS AND R ELATED U SES
2.3.4.1 Inks and Printing Operations
1,4-Dioxane has been used as a solvent in printing inks since the early 1950s (West, 1959). Although
many general references cite 1,4-dioxane as a constituent of inks and paints, few citations were
found to document the direct use of 1,4-dioxane in printing inks. The presence of 1,4-dioxane in
printing inks may be due to the minor use of methyl chloroform as a solvent in solvent-based print-
ing inks and in printing operations. Inks and coatings were listed as the destination for up to 5% of
the 715 million pounds of methyl chloroform produced in 1989. The most common solvent component
of ink formulations was toluene. Methyl chloroform was also used for contact cleaning of printing
equipment. The USEPA's 1993 Toxic Releases Inventory (TRI) reported that 37 printing operations
released a total of about 1.4 million pounds of methyl chloroform that year. Toxic Release Inventory
data are inherently problematic; for example, the printing facilities reporting represented less than
0.15% of the 70,000 printing operations in the United States at the time (USEPA, 1995a). A 1997
update to USEPA's Sector Notebook Series (which gives surveys of chemical releases in different
industries or sectors) provides 1995 i gures for 1,4-dioxane releases from two printing facilities. The
average release per facility was 8500 pounds per year (USEPA, 1997a).
Another possible source of 1,4-dioxane in inks and printing is the use of propylene glycol in both
paint and ink formulations. Formulations for both paints and inks commonly contain up to 20%
propylene glycol (Flick, 2005). 1,4-Dioxane is a known production by-product of propylene glycol
(Johnson, 2001; Pundlik et al., 2001).
1,4-Dioxane is used in the ofi ce machines industry for the dissolution of pigment via an inter-
face spray in photocopying equipment. 1,4-Dioxane is used to help inks adhere to or distribute in
plastics. Some inks used to color thermoplastic l uoropolymers, such as electrical wiring insulation
plastics, are dissolved in 1,4-dioxane (West, 1959). Inks containing resins to ensure durability—for
example, to apply permanent ink markings to golf balls—use a variety of solvents that may include
1,4-dioxane (Kikuchi and Tanaka, 2003). 1,4-Dioxane has been used as an ingredient of deinking
solvents for cleaning i ngerprint rollers (Sirchie Finger Print Labs, 1989).
2.3.4.2 Historical Restoration
1,4-Dioxane is used to remove fungal stains from paper to preserve historical papers and art works.
The solvent is also used in the conservation of oil-on-canvas and other paintings.
2.3.4.3 Painting, Coating, and Paint Stripping
Solvent-borne paints and coatings are made with solvents, binders, pigments, and additives. The
combination of binder and solvent is referred to as the paint “vehicle”; pigment and additives are
dispersed within the vehicle. Solvents comprise about 60% of the total formulation; binders, 30%;
pigments, 7-8%; and additives, 2-3%. The primary paint solvents include toluene, xylene, methyl
ethyl ketone, and methyl isobutyl ketone (Northeast Waste Management Ofi cials Association,
1998). Chlorinated solvents such as trichloroethylene and perchloroethylene were used in phos-
phatizing applications to prepare car bodies and other metal surfaces for coating and painting,
whereas methyl chloroform was often used as a solvent for paints formulated with alkyd and poly-
amide resins.
1,4-Dioxane can occur as a by-product of resin production and may be carried with resins into
paint as an impurity. Resins commonly used in paints and coatings have included vegetable oils,
alkyds, polyesters, polyamides, phenolics, polyurethanes, epoxies, silicones, acrylics, vinyls, cellu-
losics, and l uorocarbons. Coatings for metal surfaces are dominated by alkyd resins; however,
water-based acrylics, epoxies, polyurethanes, and polyesters also are used for certain applications.