Regulation and Risk Assessment of 1,4-Dioxane - Environmental Investigation and Remediation - page 290

6.4 REGULATING 1,4-DIOXANE IN FOOD, PHARMACEUTICALS,
COSMETICS, AND SUNDRIES
Chapter 2 describes the inclusion of 1,4-dioxane in food, personal care products, and pharmaceuti-
cals as a by-product of the formulation of ethoxylated surfactants and polyethylene glycols (PEGs).
1,4-Dioxane has been measured in food, pharmaceuticals, and personal care products including cos-
metics, shampoos, and lotions, as well as dish-washing detergents. Seven papers from the food chem-
istry literature identii ed 1,4-dioxane in chicken, shrimp, tomatoes, coffee, and i sh sauce (see
Table 2.13); however, 1,4-dioxane was not quantii ed and the analytical reliability in the timeframe in
which these studies were conducted was not as good as current methods. A Japanese study conducted
in 2003 identii ed 1,4-dioxane in many food products in the low ppb range, possibly associated with
contaminated irrigation or food-processing water (Nishimura et al., 2004; see Table 2.14).
The United Nations Food and Agriculture Organization created the Codex Alimentarius
Commission (also called the Food Codex) in 1963 to develop food standards and guidelines to pro-
tect consumer health. The U.S. Food and Drug Administration (FDA) and European Union agencies
operate similar regulatory programs for contaminants of foods, cosmetics, veterinary medicines,
and pharmaceuticals; all these regulatory programs promulgate standards for 1,4-dioxane.

6.4.1 F OOD R EGULATIONS
1,4-Dioxane may occur as a residual in some food additives, including glycerides and polyglycides of
hydrogenated vegetable oils (such as found in vitamin supplements) and polysorbates (present in ice
cream, gluten-free bread, and other foods). Chlorinated solvents and their stabilizers may previously
have been incorporated in food products from cleaning food-processing and canning equipment.
Where food rich in fats is stored or processed in locations where concentrations of airborne solvents
are high, solvents may partition from vapors into the food. For example, butter and lard purchased
in shops near dry cleaners contained up to 763 μg/kg perchloroethylene. Methyl chloroform has
also been measured in butter and lard, but at lower concentrations (Harrison, 2001). Presumably,
1,4-dioxane and other stabilizers prone to vapor partitioning could also enter foods stored near vapor
degreasing facilities that use 1,4-dioxane. Plastic wraps, coated paper, and other food-packaging mate-
rials manufactured by processes using solvents may have also contributed solvent residuals including
1,4-dioxane in the past, before methyl chloroform was banned by the 1996 Montreal Protocol.

6.4.1.1 1,4-Dioxane in Dietary Supplements
Glycerides and polyglycides are used as an excipient in dietary supplement tablets, capsules, and
liquid formulations (FDA, 2006). Glycerides and polyglycides are manufactured by heating a
mixture of hydrogenated vegetable oils and PEG with an alkaline catalyst, followed by neutraliza-
tion with an acid (FDA, 2006). As discussed in Chapter 2, PEG compounds often contain 1,4-dioxane
as a by-product at levels up to 5 ppm, but more commonly less than 1 ppm. Title 21 of the Code of
Federal Regulations permits up to 10 mg 1,4-dioxane per kilogram of glycerides or polyglycides as
food additives (FDA, 2006).
The FDA estimates that a person's daily exposure to 1,4-dioxane from use of glycerides and
polyglycides as an excipient in dietary supplement tablets, capsules, and liquid formulations is
800 ng. The dietary supplements are intended for ingestion in daily quantities measured in drops;
for comparison, a drop of water is about 0.025 mL or 0.025 g.
On the basis of the estimated daily per person exposure to 1,4-dioxane of less than 800 ng, the
FDA estimates that the upper-bound limit of lifetime human risk is 2.8 10 −8 or 28 in 1 billion. The

actual lifetime-averaged individual exposure to 1,4-dioxane is likely to be substantially less because
the FDA used numerous conservative assumptions in calculating the exposure estimate. The FDA
has concluded that no harm from exposure to 1,4-dioxane would result from consumption of
glycerides and polyglycides in dietary supplements.

×