Uranium & Health:

radiation and mining

Public Health Association Australia (NT Branch) 2009

Uranium & Health

• What is Uranium?

• What is Radiation?

• Health effects of radiation.

• Uranium mining.

• Uranium mining, radiation and health.

• What about safety standards?

What is Uranium

• Uranium is one of a number of naturally occurring elements that emit radiation.

• Uranium U-235 is sought in the mining process - half life of 713million years.

• However main form that exists is U-238 (around 99.3% of natural uranium), - half life of 4.5billion years.

• As uranium decays in nature, it eventually, over millions of years turns into lead.

Radon 219

Bismuth

Thorium

Radium 223

These are known as the daughter or progeny elements

Uranium 235

Lead

Uranium has 92 protons in the nucleus.

That is it’s atomic number.

U92

The atomic weight or mass is the number of protons plus the

number of neutrons.

Uranium- 235: 92 protons plus 143 neutrons.

235U92

U-235

i.e. U-235 has 3 less neutrons than U-238

What is radiation?

• Energy given off to stabilise an element (and in the process change it).

• Radiation comes in two forms:– Ionising radiation:

• travels in waves (X-rays, gamma rays) or as • particles (alpha, beta) • carries very high levels of energy that can alter

atoms creating electrically charged particles or ions.

– Non-ionising radiation:• (radio waves, heat , light) • carries enough energy to excite atoms but not

enough to create charged ions.

Types of ionising radiation

• Alpha, beta particles and gamma rays.

Ionising radiation- health effects

• High speed particles (alpha & beta) and gamma rays damage living tissue:– Damaging cells-sometime repairable– Damaging cells and causing cell multiplications-

worst from cancers- stochastic-random– Killing cells- deterministic effect.

Ionising radiation- health effects

• Depending on the dose this could occur immediately, or over many years, or generations.

• High doses- nuclear accident-bombs– From immediate death to damage to central nervous

system, cancers, reproductive damage, infertility, bleeding, ulceration, nausea, vomiting.

• Low doses- mine workers, nearby populations– Cancers, -brain, lymphatic system, oesophagus, breast

tissue, lungs, spleen kidney, liver and on skin.– Reproductive effects-prenatal developmental, reproductive

cells.

How is radiation exposure measured?

• Radiation exposure is based on how much ionising radiation enters into our body’s cells. – This is based upon the actual energy of the

source- the absorbed dose, – weighted by the nature or type of the energy-

the equivalent dose, and – then factored by what part(s) of the body are

exposed and how they are exposed- the effective dose- measured in milli-Sieverts, a measure of the biological effects of radiation exposure.

Uranium mining

On average in Australia to produce 1tonne of Uranium oxide (U308) 848tonnes of ore are mined and 11526tonnes of combined low grade ore and waste rock are left behind to be managed at the mine site.

Uranium mining, radiation and health• Exploration & mining disturb and release

radioactive material.– Leading to risk of increased radiation exposure to

miner workers and local populations.

• Mine workers primarily through inhalation of radon gas and progeny as well as radiation from the ore and other radioactive minerals and waste.

• Local populations from transportation of processed ore (risk of accident), dust from mine site (including tailings dam) and through contamination of the water table.

Human health and radon exposure.

Radon-only gas in decay chain.

Releases harmful alpha particles.

4 decay daughters solids have total half life <1hr all gamma emitters 2 alpha & 2 beta.

Lead 210 half life over 20years.

Radon mine fluxesMany uranium deposits don’t have a surface radon expression prior to disturbance.

Some, do and its variable.

Little work has been done to study or report on these sites.

Some sites where there is evidence suggest lower levels after rehabilitation some increased levels.

Gamma radiation at mine sites.

• Gamma radiation signatures vary from deposit to deposit-

– Some have major signatures- Ranger, Yeelirrie, Mary Kathleen

– Others have none- Olympic dam, Beverley.

• After most projects commence gamma radiation signatures appear to have increased.

As well as an increased risk of cancers:

a study of Namibian miners also found significant reduction in testosterone levels and increases in chromosome aberrations leading to risks to their future children of leukaemia and genetic abnormalities.

Further research is needed to explore other non-cancer risks such as strokes and heart disease.

Health risks -miners

Risk of radiationOpen cut Underground In situ leach

Radiation from ore/ on site milling

Miners – high

Locals- n/a

Miners –very high

Locals- n/a

Miners – high

Locals- n/a

Radioactive dust- source mining activity

(Includes radon gas)

Miners – high

Locals- medium

Miners – very high

Locals- possible

Miners – n/a

Locals- n/a

Radioactive dust- tailings (& radon gas)

Miners – high

Locals- medium

Miners – high

Locals- medium

Miners – low

Locals- n/a

Water table- due to fracturing of faults and membranes during mining and exploration.

Miners – possible

Locals- possible

Miners – possible

Locals- possible

Miners – high

Locals - high

Water table- leakage from tailing dam

Miners – possible

Locals- possible

Miners – possible

Locals- possible

Miners – possible

Locals- possible

Transportation accident

Miners – possible

Locals- possible

Miners – possible

Locals- possible

Miners – possible

Locals- possible

Indicative example of radiation from tailings dam

Is there a safe level of radiation exposure?• No, there is no known safe levels of exposure

to ionising radiation to avoid health risks.• As we learn more, levels of allowable

exposure for both the public and industry workers have been lowered.

year Per year Per year

1925 520mSv No limit set Until 1956

1934 ICRP 360mSv

1950 150mSv

1956 50mSv 1956 ICRP 1mSv

1990 20mSv 1987 1mSv

Workers Public

What is allowable and what is safe?

• Current radiation exposure levels for mine workers are based on what the nuclear industry considers is an acceptable risk to workers in order to produce the industry’s product and therefore to make a profit.

• The current standards do not therefore set a safe standard of radiation exposure.

Australian uranium mine worker health- the evidence.

• No long term study of mine workers from Ranger, Nabarlek or Olympic Dam.

• Small scale accidents and exposures do occur.

How do you assess the risk?

• No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individuals or to society to offset the radiation detriment it causes.

NH&MRC Recommendations for limiting exposure to ionizing radiation (1995) (Guidance note NOHSC:3022(1995)]) and National standard for limiting occupational exposure to ionizing

radiation [NOHSC:1013(1995)] republished 2002

Key References:BEIR VII Health risks from exposure to low levels of Ionising radiation

http://www.nap.edu/catalog. European Committee on Radiation Risk

<http://www.euradcom.org/2003/execsumm.htm> FOE 1998 Uranium Mining: how it affects you, Collingwood; Mudd, G 2007 Radon releases from Australian uranium mining and milling

projects: assessing the UNSCEAR approach. Jrl. Enviro Radioactivity 3 October 2007.

Mudd, G 2008 Radon sources and impacts: a review of mining and non-mining issues. Review paper Rev Environmental Sci Biotechnology 7:325-353.

Williams, B 2008 Radiation & Health energyscience.org.auWISE http://www.wise-uranium.org/Zaire, Notter et al. 1997 in Worker and Community Health Impacts Related to

Mining Operations Internationally A Rapid Review of the Literature Carolyn Stephens & Mike Ahern 2001 London School of Hygiene & Tropical Medicine.

Websites

Public Health Association of Australia<http://www.phaa.net.au> energyscience.org.au is an independent non-

governmental organisation established as a collaboration of concerned scientists, engineers and policy experts to present information to people on the issue of sustainable energy. Useful fact sheets http://www.energyscience.org.au

World Information Service on Energy http://www.wise-uranium.org/

Acknowledgements

• For critical comments- Dr Gavin Mudd- Monash University, Dr Jim Green- Friends of the Earth.

• Local colleagues, Dr Peter Tait (PHAA) Dr Hilary Tyler (MAPW) and Dr Tom Keaney (MAPW).

• Dave Sweeney- Australian Conservation Foundation, Jimmy Cocking- Arid Lands Environment Centre.