Radon in private water supplies. Jane Bradley PHE Centre for Radiation, Chemical and Environmental Hazards

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1 Radon in private water supplies Jane Bradley PHE Centre for Radiation, Chemical and Environmental Hazards

2 6 billion years ago exploding supernovae create heavy elements including uranium 2 Radon practicalities: measurements in workplaces

3 Uranium decays into radon Radon is a natural radioactive gas released from rocks and soils U-238 Half-life ~4 billion y

4 Lung cancer risk from indoor radon Indoor radon is an important lung cancer risk factor epidemiological and mechanistic evidence 2nd biggest (after smoking) UK-wide risk map accessible via PHE online services 300,000 website visits/year Proven interventions geographical risk assessment, measurement method/services, minor building work to reduce high levels

5 Radon is soluble in water Radon in water supplies Radon can enter solution if it is created from the decay of uranium (radium) present in the aquifer Short radioactive half-life of radon (3.8 d) means that most concentrations are greatly reduced through long residence and transit times. Other processes reduce concentration Agitation Heating Water surface is open to the air

6 Exposure from radon in water - 1 Potential for radiation exposure through ingestion drinking water, used in cooking etc inhalation released to indoor air (taps, kettles etc) Inhalation generally presents significantly greater radiation exposure per unit starting concentration in water Greatest release from water used in shower/bath water is heated, released / agitated in large volumes

7 Exposure from radon in water - 2 Radon concentration in water (Bq L -1 ) Radon concentration in air (Bq m -3 ) Comments 200 UK Action Level for homes 1, Radiation dose ~5 millisieverts / y 20 Average UK indoor radon level Radiation dose ~0.5 millisieverts / y <10 Radon level in most water supplies

8 Aeration Reducing radon in water mixing water with air to release radon prior to use need to ensure radon is not released to occupied space in home Granulated activated charcoal (GAC) pass water through GAC filter GAC retains radon solid decay products retained on GAC Storage to allow for radon decay (needs few half lives)

9 Directive 2013/51/EURATOM (Oct 2013) EU Directive - 1 requirements for the protection of the health of the general public with regard to radioactive substances in water intended for human consumption. Extends a 1998 Directive covering a range of radionuclides - now includes radon

10 EU Directive - 2 Member States (MS) to set Parametric values that are applicable for the monitoring of radioactive substances - not limits or safety thresholds For radon, default parametric value (PV) is 100 Bq/L MS can set a level that is inappropriate to exceed between100 Bq L -1 and 1,000 Bq L -1 can adjust PV to this chosen level MS to ensure representative monitoring to check that levels comply with PV Failures to be investigated to identify cause, assess, inform, act

11 DWI let an open tender contract to investigate implications for UK. DWI study - 1 Ricardo, PHE and British Geological Survey (BGS) Final report submitted to DWI in March Main conclusions and recommendations Treat radon in water as existing exposure situation similar to radon in homes Consider 1,000 Bq L -1 as inappropriate to exceed gives exposure similar to existing radon Action Level Retain PV at default (100 Bq L -1 ) to support investigation and optimisation.

12 Detecting radon in water DWI study - 2 Directive specifies minimum detectable concentration of 10 Bq L -1. Multiple techniques are available to achieve this including in-situ and laboratory analysed methods Techniques suffer from being spot samples radon concentrations can fluctuate significantly and require careful attention to sampling technique. UK has some established capability including in PHE and some water companies.

13 DWI study - 3 Literature reviewed for measured radon concentrations in UK public and private water LA, industry and peerreview papers. Most levels low small number in concentration ranges of interest Surface water sources are considered low hazard For groundwater sources, prototype hazard identification scheme proposed to identify areas where high concentrations might occur, based on geology, observed levels and assessment. Low high levels not likely - measurement not needed High high levels could occur - measurement needed Moderate limited evidence of elevated levels insufficient to assign L/H measurement needed

14 Radon practicalities: measurements in workplaces

15 Radon practicalities: measurements in workplaces

16 Radon in private water PHE has provided guidance for householders served by non-shared private water supply Consider radon in water if home is in shaded 1 km square on published radon map at Do standard test for radon in air If result is high, consider whether water may be source Guidance is at

17 Radon in private water non-shared Consider radon in water if home is in shaded 1 km square on published radon map at

18 Radon in private water Updated regulations for public and private water supplies are in place across the UK DWI / Defra have guidance and information :

19 Radon in private water DWI / Defra have guidance and information

20 Radon in private water DWI / Defra have guidance and information

21 Radon in private water supplies Jane Bradley PHE Centre for Radiation, Chemical and Environmental Hazards