Radionuclide Assessment Project
This project will begin to tell us where polonium-210 is occurring in Minnesota. The small number of samples involved will not give a statewide occurrence estimate, but it will tell us if polonium-210 is occurring along with other radionuclides in certain groundwater sources. Although the results will not be used for drinking water quality standards, the project may cause MDH to more closely examine this issue.
Radionuclides are naturally occurring elements found in the environment, including in groundwater aquifers. Aquifers, used as drinking water sources for 70 percent of Minnesotans, are underground layers of sand, rock, and water. Radionuclides in groundwater come from specific types of sand and rock layers, and can slowly migrate into the groundwater depending on local conditions. These naturally occurring radionuclides in groundwater vary in toxicity. Radionuclides are commonly detected at low levels in some groundwater sources, and federal standards exist to limit exposure through community water supplies.
Radionuclides are unstable, and turn into different elements. The change into a new element occurs over time, and involves the release of energy from the radionuclide. This energy, called radiation, is released in the form of rays or high speed particles called alpha particles, beta particles and gamma rays, which can be harmful to human health. Staff in the Minnesota Department of Health (MDH) are looking at specific radionuclides in groundwater for which little or no occurrence information is known in Minnesota. Polonium-210 is one radionuclide of interest because we don’t know much about its occurrence and it emits alpha particles, a very concentrated form of radiation. The U.S. Environmental Protection Agency (EPA) highlighted polonium-210 as a possible contaminant of concern for groundwater sources in 1999, but it was too difficult to measure until recently.
We will assess polonium-210 in approximately 20 public water supply wells across Minnesota, selected based on prior detections of radionuclides. The first phase of this assessment involves sampling groundwater aquifers. The earliest round of sample collection shows low levels of polonium-210 activity in most deep groundwater aquifers. A few samples contained higher levels of polonium-210 activity in the east-central portion of the state. This analysis is ongoing and sampling is not yet complete. Following sample collection and analysis, results will be shared with the community water supplies along with EPA and U.S. Geological Survey researchers to determine whether more work should be conducted in Minnesota to understand exposure to polonium-210. MDH currently applies the EPA drinking water standard for naturally occurring radionuclides, which includes polonium-210. However, the health risks of polonium-210 alone have not been assessed, and no specific polonium-210 drinking water standard exists.
$1,150,000 the first year and $1,150,000 the second are for addressing public health concerns related to contaminants found in Minnesota drinking water for which no health-based drinking water standards exist, including accelerating the development of health risk limits, including triclosan, and improving the capacity of the department's laboratory to analyze unregulated contaminants.
Pace Analytical Services, Inc. was contracted to measure levels of polonium-210, lead-210, total gross alpha, and other contaminants as part of the overall study.
Pace Analytical Services, Inc. provided accurately and reliably measured levels of polonium-210, lead-210, total gross alpha, and other contaminants of the study samples.