As the Arizona Daily Star reported today, the EPA is considering lowering the allowed concentration of dioxane in drinking water. That would cost the city millions to build a new water purification plant.

Current EPA standards allow up to three parts per billion. Tucson Water mitigates some contaminated water from Tucson’s south side by diluting the water and now delivers water with 1.15 parts per billion dioxane. The EPA says that under current standards, drinking the water for 70 years would give you a one in 1 million chance of getting cancer from dioxane. That’s about the same as the chance of getting hit by lightning in the U.S.

Here’s the rest of the story:

The EPA is running into trouble over these standards from the Department of Defense and some industry groups such as the Alliance for Environmental Responsibility and Openness (AERO). AERO says that the “only studies that show … dioxane causes tumors are very high dose rodent studies.” There is no reason to assume, as the EPA does, that there is any evidence to suggest a “proportional or linear relationship between health problems experienced in rodents at high doses and those that would be expected to occur in humans exposed to the chemical in more typical environmental circumstances.”

The Department of Defense (DOD) warned the EPA that it may face challenges under the Data Quality Act because the EPA changed conclusions of peer-reviewed studies after the fact. The changes included “the number of animals, the number of animals that had tumors, the doses given to the animals, and changes in both the statistical procedures and . . . calculations,” DOD says.

What all that means is that the EPA may be mired in lawsuits before it can impose any changes.

By the way, dioxane is a byproduct of the production of materials used in cosmetics, notably sodium myreth sulfate and sodium lauryl sulfate (check your shampoo). Since 1979, the U.S. Food and Drug Administration has conducted tests on cosmetic raw materials and finished products for the levels of dioxane, and found dioxane levels up to 1410 parts per million(ppm) in raw ingredients, and levels up to 279 ppm in off the shelf cosmetic products. But EPA bureaucrats are now trying to scare us with three parts per billion.

The chemophobia of the EPA seems founded on a political agenda and upon pure guess work based in part on the “linear threshold” hypothesis. Simply stated, this hypothesis maintains that if a large dose is harmful, then smaller doses are also harmful in proportion. That is equivalent to saying that the harm from one man falling 100 feet is equivalent to that of 100 men falling one foot. This reasoning is applied to many natural phenomena and potentially carcinogenic substances to justify regulation and government programs.