Uranium

1
Uranium Healthradiation and mining

• Public Health Association Australia (NT Branch)
  2009

2
Uranium Health

• What is Uranium?
• What is Radiation?
• Health effects of radiation.
• Uranium mining.
• Uranium mining, radiation and health.
• What about safety standards?

3
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.

4
Uranium 235
Thorium
These are known as the daughter or progeny
elements
Radium 223
Radon 219
Bismuth
Lead
5
Uranium has 92 protons in the nucleus. That is
its 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
6
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.

7
Types of ionising radiation

• Alpha, beta particles and gamma rays.

8
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.

9
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.

10
How is radiation exposure measured?

• Radiation exposure is based on how much ionising
  radiation enters into our bodys 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.

11
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.
12
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.

13
Human health and radon exposure.
Radon-only gas in decay chain. Releases harmful
alpha particles. 4 decay daughters solids have
total half life lt1hr all gamma emitters 2 alpha
2 beta. Lead 210 half life over 20years.
14
Radon mine fluxes
Many uranium deposits dont 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.
15
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.

16
Health risks -miners
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.
17
Risk of radiation
18
Indicative example of radiation from tailings dam
19
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.

Workers
Public
20
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 industrys product and
  therefore to make a profit.
• The current standards do not therefore set a safe
  standard of radiation exposure.

21
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.

22
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.
• NHMRC Recommendations for limiting exposure to
  ionizing radiation (1995) (Guidance note
  NOHSC3022(1995)) and National standard for
  limiting occupational exposure to ionizing
  radiation NOHSC1013(1995) republished 2002

23
Key References

• BEIR VII Health risks from exposure to low levels
  of Ionising radiation http//www.nap.edu/catalog.
  
• European Committee on Radiation Risk
  lthttp//www.euradcom.org/2003/execsumm.htmgt
• 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 7325-353.
• Williams, B 2008 Radiation Health
  energyscience.org.au
• WISE 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.

24
Websites

• Public Health Association of Australia
• lthttp//www.phaa.net.augt
• 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/

25
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.