EPA may change Dioxane standards in Tucson water

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.



  1. What I find fascinating about all this is the quote from the Star story:
    Under the current standard, a person would have to drink two quarts of the affected water a day for 70 years to get a 1-in-a-million exposure risk for cancer, according to the EPA. The new EPA standards will lower those amounts, although Biggs said it won’t necessarily be lowered by nine times – the cancer potency increase determined by the EPA.

    What is being referred to is “excess cancer risk level” or ECRL….which I doubt many understand…maybe you could do a post on this…

    Anyway, what we do not have in this country is the ability to look at comparative risks and costs to reduce the risks….basically if you eat one peanut butter sandwich  you would probably experience as much cancer increase risk as drinking the water with the target level of diozane for 70 years.  You also have a higher likelihood of being hit by a meteorite.

    However, the fear mongering approach to regulation lets the government impose enormous additional costs on municipal water ratepayers without any meaningful improvement of health or life span. It is a costly racket. 

    I can’tr wait until they decide that hydrogen is potentially toxic and that must be removed from our drinking water.

  2. The American Cancer Society claims we have a 44% chance of contracting cancer of some kind during our lifetime. The EPA says dioxane might cause a 1 in 1 million chance of contracting cancer. Therefore, drinking water with 3 ppb dioxane may increase your chances of contracting cancer from 44% to 44.0001%.

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