Radium (radium-226 and radium-228)

(updated 2022)

Guideline

Radium-226 and radium-228 should be determined if the gross alpha radioactivity in drinking water exceeds 0.5 Bq/L, or if the gross beta activity (with the contribution of potassium-40 subtracted) exceeds 0.5 Bq/L.

General description

Radium isotopes are formed as a result of radioactive decay of isotopes from the natural uranium and thorium decay series. The two most significant isotopes in this process, in terms of radiological health, are radium-226 (uranium series) and radium-228 (thorium series), which have half-lives of 1620 years and 5.8 years, respectively. Radium-224 is generally not considered in assessments of radiological health effects due to its short half-life of 3.66 days and the minor contribution to radiation dose per unit of intake.

Drinking water sourced from groundwater can contain activity concentrations of radium at levels that may present a health concern (ARPANSA 2008, Kleinschmidt et al. 2011, Walsh et al. 2014). Concentrations in surface water are likely to be extremely low (ARPANSA 2008).

A number of chemical and physical processes contribute to the concentration of radium in groundwater. Physical processes of weathering, recoil¹, decay, adsorption-desorption and precipitation during transport within aquifers will affect the radium content. Chemical processes are largely dependent on the chemical composition of the water. Generally, radium concentrations are considered to have a broad correlation with total dissolved solids (TDS) and salinity (IAEA 2014). Concentrations of radium isotopes in groundwater will also vary according to the mineralogy of the host rock for the aquifer (IAEA 2014a).

Typical values in Australian drinking water

In supplies derived from groundwater sources, radium-226 and radium-228 concentrations vary considerably depending on the aquifer (Kleinschmidt 2011). Radium-226 concentrations in Australian surface water supplies are generally below 0.05 Bq/L. A small number of groundwater supplies exhibit concentrations up to, or exceeding, 0.5 Bq/L (ARPANSA 2008, Kleinschmidt et al. 2011, Walsh et al. 2014). These studies have shown that the values of radium in Australian drinking waters derived from groundwater supplies may be an order of magnitude higher than the reference values reported in the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR 2000).

Analysis

Generally, analysis for radium isotopes is only required if either gross alpha or gross beta activities exceed 0.5 Bq/L (refer to Chapter 7 and Information Sheet 2.2).

Standard methods (or validated methods) should be used to determine concentrations of radium. Table 1 lists some recommended standard methods from the International Organization for Standardization (ISO) and the American Public Health Association (APHA). Sample analysis should be carried out as soon as possible and within 2-3 days of sample collection if a determination of radium-224 is required.

Table 1. Recommended standard method for the analysis of radium

Method Reference	Sample preparation	Measurement technique	Radionuclide
ISO 13165 Radium-226 - Part 1 (2013)	Precipitation	Liquid scintillation counting	Ra-226
ISO 13165 Radium-226 - Part 3 (2016)	Precipitation	Gamma counting	Ra-226
ISO 22908 Radium-226 and radium-228	Precipitation	Liquid scintillation counting	Ra-226 and Ra-228
APHA 7500-Ra B (2017)	Precipitation	Proportional counting or alpha scintillation counting	Alpha emitting radium isotopes
APHA 7500-Ra D (2017)	Sequential precipitation	Proportional counting and/or alpha scintillation counting	Ra-228 or Ra-226 and Ra-228
APHA 7500-Ra E (2017)	Precipitation	Gamma counting	Ra-224, Ra-226, Ra-228

Note: the required detection limits should be considered when selecting an appropriate analytical method. The method selected should take into account the determination of the annual dose, as described in Chapter 7, Section 7.6.2. It is recommended that the detection limit be 20% of the value required to meet the reference level.

Health considerations

The major evidence concerning radium exposure effects come from epidemiological studies of radium dial painters (Rowland et al. 1978). Exposure of the workers to large doses of radium indicated a positive dose response relationship in humans for bone and head and neck sarcomas. Once radium has entered the body, the metabolic behaviour of radium is similar to that of calcium and an appreciable fraction of ingested radium is deposited in bone tissue where it is retained for a long time. The internal radiation dose from radium-226 is due mainly to the emission of alpha particles. The internal radiation dose from radium-228 is due mainly to the emission of beta particles.

Epidemiological studies for low-level exposure to naturally occurring radionuclides in drinking water show no clearly demonstrated health effects (Guseva Canu et al. 2011, UNSCEAR 2018).

Derivation of guideline

The dose from radium-226 and radium-228, and any other radioactive isotopes present in drinking water, should be estimated using the method described in Chapter 7, Section 7.6.2.

¹ Nuclear recoil during the radioactive decay of naturally occurring radionuclides can create disequilibrium when the recoil liberates the nuclide from its mineral lattice.

References

APHA, AWWA, WEF (American Public Health Association, American Water Works Association, Water Environment Federation) (2017). 7500-Ra B Precipitation Method.

APHA, AWWA, WEF (American Public Health Association, American Water Works Association, Water Environment Federation) (2017). 7500-Ra D Sequential Precipitation Method.

APHA, AWWA, WEF (American Public Health Association, American Water Works Association, Water Environment Federation) (2017). 7500-Ra E Gamma Spectroscopy Method.

ARPANSA (Australian Radiation Protection and Nuclear Safety Agency) (2008). The Radioactive Content of Some Australian Drinking Waters. Technical Report Series No 148.

Guseva Canu I, Laurent O, Pires N, Laurier D, Dublineau I (2011). Health Effects of Naturally Radioactive Water Ingestion: The Need for Enhanced Studies. Environmental Health Perspectives 119(12): 1676-1680.

IAEA (International Atomic Energy Agency) (2014). The Environmental Behaviour of Radium: Revised Edition. Technical Report Series No. 476. ISBN 978–92–0–143310–7, Vienna.

IAEA (International Atomic Energy Agency) (2014a). Analytical Methodology for the Determination of Radium Isotopes in Environmental Samples. Analytical Quality in Nuclear Applications Series No. 19. ISSN 2074-7659, Vienna.

ICRP (International Commission on Radiological Protection) (2012). Compendium of Dose Coefficients based on ICRP Publication 60. ICRP Publication 119. Ann. ICRP 41(Suppl.).

ISO (International Organization for Standardization) (2014). Water quality - Radium-226 - Part 1: Test method using liquid scintillation counting ISO, International Standard ISO 13165-1:2013, Geneva, Switzerland.

ISO (International Organization for Standardization) (2016). Water quality - Radium-226 - Part 3: Test method using coprecipitation and gamma-spectrometry ISO, International Standard ISO 13165-3:2016, Geneva, Switzerland.

ISO (International Organization for Standardization) (2020). Water quality - Radium-226 and radium-228 - Test method using liquid scintillation counting ISO, International Standard ISO/ 22908:2020, 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.

Rowland RE, Stehney AF, Lucas HF (1978). Dose-response relationship for female radium dial workers. Radiation Research, 76: 368–383.

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.

UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) (2018). Sources and Effects and risks of ionizing radiation. UNSCEAR 2017 Report to the General Assembly, Scientific Annexes A and B. ISBN: 978-92-1-142322-8, New York.

Walsh M, Wallner G, Jennings P (2014). Radioactivity in drinking water supplies in Western Australia. Journal of Environmental Radioactivity, 130: 56-52.