Radionuclides, Specific Alpha and Beta Emitting
(updated 2022)
Guideline
There are no specific reference levels set for specific alpha or beta emitting radionuclides.
Specific alpha or beta emitting radionuclides should be determined if the gross alpha screening value in drinking water exceeds 0.5 Bq/L, or if the gross beta screening value (with the contribution of potassium-40 subtracted) exceeds 0.5 Bq/L, or if there is a specific reason to analyse for individual radionuclides.
General description
Alpha emitters:
Alpha emitters may be present in drinking water in low concentrations. Significant alpha emitters are naturally occurring radionuclides from the uranium and thorium decay chains. Depending on the source of the drinking water there may be areas with high activity concentrations for some of these alpha emitters. The most significant of these are radium-226, polonium-210 and uranium isotopes.
Radium-226, polonium-210 and the uranium isotopes have relatively long half-lives and may be present in drinking water. Radium-226 is commonly found in groundwater, whereas polonium concentrations are usually lower in concentration and uranium could be present in some groundwater (ARPANSA 2008, Kleinschmidt et al. 2011, Walsh et al. 2014).
Refer to the Radium fact sheet for more information on radium-226.
Beta emitters:
There are several radionuclides that are classified as beta emitters and may occasionally be present in drinking water. Long-lived radionuclides in this group are the naturally occurring isotopes potassium-40, lead-210 and radium-228 as well as the artificial radionuclides caesium-137 and strontium-90. Tritium, another radionuclide in this group, is present in the environment both from natural sources and as a result of nuclear fall-out and nuclear power generation.
Levels of strontium-90 and caesium-137 in the Australian environment have decreased substantially since atmospheric testing of nuclear weapons ceased, and these radionuclides are not detectable in drinking water. These radionuclides may be present as a result of transient contamination following an event such as a nuclear or radiological emergency.
Potassium-40 occurs naturally in a fixed ratio to stable potassium. Potassium is an essential element for humans and is absorbed mainly from the ingestion of food. Potassium-40 in the body is maintained at a constant level independent of intake.
Radium-228 is commonly found in groundwater supplies. Refer to the Radium fact sheet for more information on radium-228.
Typical values in Australian drinking water
Limited data is available for anthropogenic (human-made) radionuclides such as strontium-90 and caesium-137. Levels can reasonably be expected to be negligible due to Australia’s limited and regulated nuclear industry and protection measures for water supplies.
Knowledge of lead-210, polonium-210 and other naturally occurring thorium radioisotopes is also limited. However, they are expected to be at levels that are low due to their reactive nature and tendency to adsorb readily onto surfaces. Elevated concentrations of polonium-210 have been reported, which is suspected to be caused by the presence of scale causing a proximal source to the sampled water (Kleinschmidt et al. 2008).
Concentrations of radium-226 and radium-228 may be elevated and may exceed 0.5 Bq/L in some groundwater supplies (ARPANSA 2008, Kleinschmidt et al. 2011, Walsh et al. 2014).
Treatment of drinking water
Treatment processes involving ion exchange or reverse osmosis will effectively remove radionuclides such as lead-210, strontium-90 and caesium-137. There is no suitable treatment to remove tritium.
Analysis
For the initial screening analysis, gross alpha and gross beta activity and potassium-40 are determined as described in Information Sheet 2.2.
Table 1 provides some references to standard methods of analysis for specific alpha and beta radionuclides from the International Organization for Standardization (ISO) and the American Public Health Association (APHA). It is important to note that some of these radionuclides may also have gamma emissions and therefore gamma spectrometry techniques could also be considered.
The US Environmental Protection Agency (USEPA 2016) have compiled a list of approved methods for the analysis of radionuclides in drinking water. ASTM International (formerly known as American Society for Testing and Materials) Annual Book of ASTM Standards (2018) also provides some radionuclide specific standard methods.
Table 1. Recommended standard method for the analysis of specific alpha and beta emitting radionuclides
APHA 7120 B Gamma emitters (2017)
Direct measurement – no sample preparation required
High resolution gamma spectrometry
ISO 10703 Gamma emitters (2007)
Direct/evaporation/evaporation with iodine retention
High resolution gamma spectrometry
ISO 13161 Polonium-210 (2012)
Evaporation, autodeposition
Alpha spectrometry
APHA 7500-Cs B Radioactive caesium (2017)
Precipitation
Beta counting/gamma counting
ISO 13163 Lead-210 (2013)
Co-precipitation, separation using extraction chromatography
Liquid scintillation counting
APHA 7500-Sr A Radioactive strontium (2017)
Precipitation
Proportional counting
ISO 13160 Stronium-89/90 (2012)
Precipitation/liquid-liquid extraction/extraction chromatography
Proportional counting/liquid scintillation counting
APHA 7500-3H Tritium (2017)
Distillation
Liquid scintillation counting
ISO 9698 Tritium (2010)
Distillation
Liquid scintillation counting
Note: the required detection limits should be considered when selecting an appropriate analytical method.
Health considerations
Once lead-210 has entered the body it will concentrate in bone where it remains for a long time. The radiation dose from lead-210 is due mainly to the emission of alpha particles from its progeny, polonium-210. In general, polonium in the blood stream will be deposited in the spleen, kidneys, liver and in bone where it remains for a short time. Immediate health risks from drinking water with low levels of lead-210 are very small.
In principle, lead-210 may increase the risk of bone cancers; however, no link has been demonstrated, either in animal studies or epidemiological studies.
Potassium-40 occurs naturally in the environment with stable potassium at the ratio of 27.6 Bq of potassium-40 per gram of stable potassium. The potassium content of the body is under strict control to sustain biological processes and it is not influenced by variations in environmental levels. While in the body, potassium-40 emits beta particle and gamma ray emissions. The dose due to this naturally occurring radionuclide in bodily tissues has been determined to be 0.165 and 0.185 mSv/year for adults and children, respectively (UNSCEAR 2000).
Estimation of dose
The dose from individual alpha or beta emitting radionuclides should be determined using the method described in Chapter 7, Section 7.6.2.
References
APHA, AWWA, WEF (American Public Health Association, American Water Works Association, Water Environment Federation) (2017). 7120 B Gamma Spectroscopic Method.
APHA, AWWA, WEF (American Public Health Association, American Water Works Association, Water Environment Federation) (2017). 7500 B Radioactive Cesium-Precipitation Method.
APHA, AWWA, WEF (American Public Health Association, American Water Works Association, Water Environment Federation) (2017). 7500-Sr B Radioactive Strontium and Strontium-90 Precipitation Method.
APHA, AWWA, WEF (American Public Health Association, American Water Works Association, Water Environment Federation) (2017). 7500-3H B Tritium Liquid Scintillation Method.
ARPANSA (Australian Radiation Protection and Nuclear Safety Agency) (2008). The Radioactive Content of Some Australian Drinking Waters. Technical Report Series No 148.
ASTM (ASTM International) (2018) Annual Book of ASTM Standards. https://www.astm.org/Standard/standards-and-publications.html
ISO (International Organization for Standardization) (2007). Water quality – determination of the activity concentration of radionuclides – Method by high resolution gamma-ray spectrometry. ISO, International Standard ISO 10703:2007, Geneva, Switzerland.
ISO (International Organization for Standardization) (2010). Water quality – determination of tritium activity concentration – liquid scintillation counting method. ISO, International Standard ISO 9698:2010(E), Geneva, Switzerland.
ISO (International Organization for Standardization) (2011). Water quality – Measurement of Polonium 210 Activity Concentration in Water by Alpha Spectrometry. ISO, International Standard ISO 13161:2011, Geneva, Switzerland.
ISO (International Organization for Standardization) (2012). Water quality – strontium 90 and strontium 89 – Test methods using liquid scintillation counting or proportional counting. ISO, International Standard ISO 13160:2012 Geneva, Switzerland.
ISO (International Organization for Standardization) (2013). Water quality – Lead-210 – Test method using liquid scintillation counting. ISO, International Standard ISO 13163:2013, Geneva, Switzerland.
Kleinschmidt R, Black J, Akber R (2011). Mapping radioactivity in groundwater to identify elevated exposure in remote and rural communities. Journal of Environmental Radioactivity, 102: 235-243.
Kleinschmidt R, Akber R (2008). Naturally occurring radionuclides in materials derived from urban water treatment plants in southeast Queensland, Australia. Journal of Environmental Radioactivity, 99: 607-620.
UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) (2000). Sources, effects and risks of ionising radiation. UNSCEAR, report ISBN 92-1-142143-8, New York.
USEPA (United States Environmental Protection Agency) (2016). Approved Drinking Water Analytical Methods – Radionuclides https://www.epa.gov/dwanalyticalmethods/approved-drinking-water-analytical-methods.
Walsh M, Wallner G, Jennings P (2014). Radioactivity in drinking water supplies in Western Australia. Journal of Environmental Radioactivity, 130: 56-62.
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