National Drinking Water Database

• Read the Research
• Get a Water Filter
• Tips for Safe Water
• FAQs
• EWG Needs Your Help. As little as $5 can help.

Radon in Wisconsin

---

Radon is a radioactive breakdown product of radium and uranium in soil, rock and water; it is often present in groundwater. [read more]

Radon Radon is a colorless, odorless, tasteless and radioactive gas. Radon is formed by the normal radioactive decay of uranium and radium. Underground rock containing natural uranium continuously releases radon gas into groundwater in contact with it. As a gas, radon is readily released from surface water; consequently, groundwater has potentially much higher concentrations of radon than surface water (World Health Organization 2004a). Radon itself is an unstable element that decays into radiation and other, smaller elements that are called "radiation decay products" or "daughter species" (Agency for Toxic Substances and Disease Registry (ATSDR 2008e). Human exposure to radon has been linked to severe respiratory disease, harmful kidney effects, sexual maturation effects, mutations, and increases in lung cancer deaths (ATSDR 2008e). Studies from 11 large cohorts of underground miners have all produced data showing increase in lung cancer risk from exposure to radon. There are also dozens of epidemiologic studies linking residential radon exposure and lung cancer (ATSDR 2008e). The amount of radon in groundwater is highly variable and dependent on the chemical concentration of radium-226 in the surrounding soil or rock. Radium is widely present in the minerals making up the Earth's crust, so radon is present virtually everywhere on Earth but particularly in the air over land and in buildings (WHO 2004a).

The Most Polluted Communities in Wisconsin

81 water utilities reported detecting Radon in tap water since 2004, according to EWG's analysis of water quality data supplied by state water agencies

Ranked by highest average Radon level

Rank	System	Population Served	Positive test results of total reported tests	Average Level (Range)
1	Colby Waterworks Colby, WI	1,600	1 of 1	13900 pCi/L (13900 pCi/L)
2	Bethel Nursing & Rehab Center Arpin, WI	225	2 of 2	9450 pCi/L (6800 to 12100 pCi/L)
3	Mattoon Waterworks Mattoon, WI	450	1 of 1	2390 pCi/L (2390 pCi/L)
4	Thorp Waterworks Thorp, WI	1,565	1 of 1	1650.85 pCi/L (1650.85 pCi/L)
5	Village of Lake Hallie Waterworks Chippewa Falls, WI	3,500	2 of 2	1625 pCi/L (1560 to 1690 pCi/L)
6	Gresham Waterworks Gresham, WI	534	6 of 6	884.1 pCi/L (44.9 to 4930 pCi/L)
7	City of Hayward Water Utility Hayward, WI	2,313	2 of 2	769 pCi/L (538 to 1000 pCi/L)
8	St Croix Falls Waterworks St Croix Falls, WI	2,079	1 of 1	738 pCi/L (738 pCi/L)
9	Hixton Waterworks Hixton, WI	443	1 of 1	583 pCi/L (583 pCi/L)
10	Lake Delton Waterworks Lake Delton, WI	2,599	1 of 1	568.7 pCi/L (568.7 pCi/L)

Health Based Limits for Radon

Standard	Description	Level
One in one million (10-6) Cancer Risk	The concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 1,000,000. Source: U.S. Environmental Protection Agency.	1.5 pCi/L
One in ten thousand (10-4) Cancer Risk	The concentration of a chemical in drinking water corresponding to an excess estimated lifetime cancer risk of 1 in 10,000. Source: U.S. Environmental Protection Agency.	150 pCi/L

Violation Summary for Radon in Wisconsin

There are no violations reported for this contaminant in Wisconsin