Regulatory Policy Implications of 1,4-Dioxane - Environmental Investigation and Remediation - page 474

and organic products for violating California's Safe Drinking Water and Toxic Enforcement Act of
1986 (Proposition 65) by failing to remove 1,4-dioxane from body washes, gels, and liquid dish
soaps (Phillips, 2008). In 2009, the Saudi Food and Drug Authority pulled eight types of shampoos
from store shelves in Saudi Arabia, following the sampling of 84 brands of shampoo available in the
Saudi market and detection of 1,4-dioxane in eight shampoos. The action was taken over the
concern that extended exposure to 1,4-dioxane can be damaging to the liver and kidney (Abdullah,
2009). Similar actions were taken for shampoos produced in India and Iran by authorities in Kuwait
and the United Arab Emirates following the Saudis' analysis of shampoos.
The Saudi response seems to neglect the relevance of the route of exposure, as dermal exposure
is not known to be a major pathway for 1,4-dioxane toxicity. The relatively high NOAELs and the
absence of dose-response values for dermal exposure to 1,4-dioxane make it difi cult to estimate the
health effects from repeated exposure to low levels of 1,4-dioxane in contaminated shower water or
in shampoos and soaps. The majority of published 1,4-dioxane risk summaries conclude that the risk
of adverse health effects from dermal exposure to low concentrations in water or sundries is not
signii cant (see Sections 5.6 and 6.5.4). There is a notion held by some that a small amount of a
chemical carcinogen in a children's product is not dangerous because the level is very low, and low
doses of cancer-causing chemicals are safe because there is a threshold for cancer induction. That
notion is refuted by two prominent environmental oncologists who take issue with the presence of
1,4-dioxane in shampoos and in children's bath products and advance another notion: “The com-
bined effects of our lifetime exposure to dioxane and other carcinogens can create synergistic effects,
so what may look like low exposure levels for any one compound adds up and even multiplies”
(Davis and Heberman, 2007).
The question of whether adverse synergistic effects of 1,4-dioxane with other toxins actually
occur remains unproven and is an important topic for research in the arena of computational toxicol-
ogy. Does the detection of 1,4-dioxane in shampoos justify removing products from store shelves?
The Saudi Food and Drug Authority applied the precautionary principle and decided that removing
eight shampoo products still leaves consumers with 76 safe shampoos and ensures that no exposure
to 1,4-dioxane occurs. The Saudi newspaper noted, “There are processes that can remove this con-
taminant, but some companies forego the added expense to ensure their products do not contain the
solvent” (Abdullah, 2009).
Nearly a million people in Daegu, South Korea's fourth largest city, were also blindsided by 1,4-
dioxane in their drinking water supply, the Nakdong River. Daegu Metropolitan Waterworks
reported in January 2009 that 1,4-dioxane levels at the Maegok water purii cation plant rose to
54 μg/L, exceeding the 50 μg/L World Health Organization Guideline for Drinking-Water Quality
(Dong-A Ilbo, 2009). The 1,4-dioxane concentrations peaked at 88 μg/L, then stayed consistently at
65 μg/L at one monitoring point for one week. In 2003, concentrations in the Nakdong River reached
119 μg/L (see Table 6.13). The source of the 1,4-dioxane is upstream discharges from polyester
manufacturing plants.
10.6 THE PROMISE OF GREEN CHEMISTRY
Can we avoid being blindsided by another 1,4-dioxane-like environmental contaminant? The existing
regulatory framework for testing new chemical products for toxicological and environmental fate and
transport properties has had limited effectiveness. Existing law has not prevented contaminants like
MTBE, nitrosamine compounds [nitrosodimethylamine (NDMA), nitrosodiethylamine (NDEA) and
others], 1,4-dioxane, polybrominated diphenyl ether (PBDE) l ame retardants, poly l uorinated octanoic
acid (PFOA, also called C-8), perl uorooctane sulfonic acid (PFOS) and others from being widely used
and released into the environment. Some of these contaminants are particularly widespread and have
attained global circulation; the insidious nature of PBDE's includes detection in polar bear fat and
human breast milk (Stavelova, 2008), and the pervasive nature of PFOA includes detection in most
human blood samples.