1,4-Dioxane Chemistry, Uses, and Occurrence - Environmental Investigation and Remediation - page 90

1,4-dioxane for routine quality-control testing, which could produce a laboratory waste stream with
a substantial volume of 1,4-dioxane over time.

2.4.1.1 Personal Care Products: Detergents, Shampoos, and Sundries
1,4-Dioxane was historically present in the part per million range in alcohol ethoxy sulfate (AES)
compounds. Sodium laureth sulfate [the compound sodium 2-(2-dodecyloxyethoxy) ethyl sulfate,
CASRN 3088-31-1; also called sodium lauryl ether sulfate] in particular had elevated levels of 1,4-
dioxane, as high as 500 ppm. Sodium laureth sulfate is a component of anionic surfactants in deter-
gents and shampoos. Powdered detergents typically used as much as 12% AES, whereas liquid
detergents used as much as 18% AES, and dish-washing detergents may contain as much as 27%
AES (Greek and Layman, 1989; Stepan Company, 2006). In addition to sodium laureth sulfate, the
common shampoo, detergent, and dish-washing soap ingredients containing ammonium laureth
sulfate and triethanolamine laureth sulfate may also contain 1,4-dioxane as a trace contaminant. In
the 1980s, these ingredients contained elevated levels of 1,4-dioxane. Ammonium laureth sulfate
contained 1,4-dioxane from 288 to 1282 ppm; sodium laureth sulfate had from 69 to 340 ppm. In
1988, 400 million pounds of ethoxylated alcohol surfactants were used in household detergents
in the United States (Talmage, 1994). Some earlier formulations of laundry presoak spray had
particularly high levels of 1,4-dioxane. In one of six samples of laundry presoak spray analyzed,
1,4-dioxane was detected at a concentration of 15.0 wt% (USEPA, 1992).
Since the 1950s, quality-control testing for surfactant production included determining the
hydrophilic versus lipophilic balance or relative solubility number of nonionic surfactants. The rela-
tive solubility number is the volume in milliliters of distilled water necessary to produce persistent
turbidity in a benzene and 1,4-dioxane solvent system consisting of 1 g of surfactant sample and
30 mL of solvent. To avoid using toxic solvents, the test now uses toluene and ethylene glycol dim-
ethyl ether (Wu et al., 2004).
In 1979, the U.S. Food and Drug Administration (FDA) announced that hundreds of cosmetics
products contained 1,4-dioxane. The announcement cautioned that the potential associated risk was
unknown (Washington Post, 1979). In the early 1980s, the FDA tested 100 samples of ethoxylated
surfactant ingredients used in personal care products and found that 81% of ingredients tested con-
tained detectable levels of 1,4-dioxane. Results of the FDA study are summarized in Table 2.8
(FDA, 1981). In i nished products in the sundries category, the same study found that 2 of 11 sam-
ples contained greater than 100 ppm 1,4-dioxane; 5 of 11 contained 1,4-dioxane between 10 and
100 ppm; one sample had less than 10 ppm; and three samples did not detect 1,4-dioxane at a report-
ing limit of 0.5 ppm (FDA, 1980, 1981). Table 2.9 summarizes levels of 1,4-dioxane in shampoos,
bath, and sundry products.
Following the realization that 1,4-dioxane is present in cosmetics, shampoos, and detergents as
an impurity of surfactants and emulsii ers, surfactant producers sought to reduce the amount of 1,4-
dioxane formed. The degree of reduction in the levels of 1,4-dioxane present varied considerably in

TABLE 2.8
Summary of 1,4-Dioxane Analysis of Ethoxylated Raw Materials as of September 30, 1981

Range of Dioxane Detections Number of Samples in This Range (Out of 100)

Levels above 100 ppm 22

Levels between 10 and 100 ppm 36

Levels between 0.5 and 10 ppm 23

Not detected above 0.5 ppm 19

Source: Food and Drug Administration (FDA), 1981, Progress report on the analysis of cosmetics raw materials and i n-
ished cosmetics products for 1,4-dioxane. Division of Cosmetics Technology, Food and Drug Administration 15.