Transcript Is depleted uranium a carcinogen?

Is depleted uranium a
carcinogen?
Keith Baverstock PhD
Department of Environmental Science
University of Kuopio
Finland
Assessing cancer risk
• Start with environmental contamination
• Has the contamination led to exposure?
• Has the exposure led to epidemiologically
detectable cancer in humans?
• Has the exposure led to detectable cancer
in animals?
• Has the exposure led to genotoxic
damage in cells in culture?
In the case of uranium
Environmental
contamination?
Human exposure?
Yes, probably widespread in Iraq,
much more limited in Balkans
Not evident in UK or German military
but measured in workers at DU
munitions facility in the US
Human epidemiological
evidence?
Apart from studies by Iraqi doctors
no study of sufficient power.
Some human evidence from 27
veterans with DU in urine.
Yes, published evidence but limited.
Evidence in animals?
Evidence of
genotoxicity
Yes, several published reports.
Evidence of exposure?
• German service personnel in Balkans
show no evidence in urine tests neither do
UK service personnel in Iraq.
• However, workers at a DU munitions
factory in the US and some local residents
show evidence of exposure to DU
aerosols 20 years after the closure of the
facility.
Iraq tooth study
• Measurements of DU will be made on
teeth shed naturally by children from two
regions of Iraq. As uranium tends to locate
in bone and teeth this study should
demonstrate conclusively whether or not
the DU contamination in Iraq is “bioavailable” and thus a potential hazard to
health.
Human epidemiological evidence
• No studies, other than those performed by
Iraqi doctors, of sufficient power, have been
conducted in order to determine whether DU
is carcinogenic. Of UK servicemen serving in
Iraq only 2092 claimed exposure to DU and
their cancer incidence (based on 7 cancers)
was no higher than some 26,000 non
exposed. However, measurements of DU in
urine showed no excess in 440 UK
servicemen.
Other human evidence
• “Continued evidence of a weak genotoxic
effect from the on-going DU exposure as
measured at the HPRT (hypoxanthineguanine phosphoribosyl transferase) locus
and suggested by the fluorescent in-situ
hybridization (FISH) results in peripheral
blood recommends the need for continued
surveillance of this population.”
Health Surveillance of Gulf War I veterans (27 with raised DU) exposed to DU.
McDiarmid et al 2007, Health Physics, 93 60 to 72.
Animal studies
• Rats which inhaled uranium ore dust exhibit a
dose dependent risk of malignant lung cancer.
• Soft tissue sarcomas formed in rats with
embedded DU (Hahn et al 2002)
• Leukaemia can be induced in mice implanted
with DU and subsequently injected with
transformable murine hemopoietic cells. The
injected cells become malignant in mice with
high levels of DU significantly more frequently
than controls. (Miller et al 2006)
Laboratory indicators of genotoxicity
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Genomic instability
Cell transformation
Chromosome aberrations
Mutation induction
Induction of oxidative damage to DNA
DNA double strand breaks
DNA adduct formation
Changes in gene activation/expression
Changes in protein expression
Blue text indicates observations in human subjects
All of these have been ….
…… reported in peer reviewed publications,
the majority since 2002 when the Royal
Society Reports (pts I and II) and WHO
Monograph were published.
In many of these studies nickel was used a
comparison and usually produced a similar
effect. Nickel is categorised as Group I (a
human carcinogen) by the International
Agency for Research on Cancer (IARC).
Thus,
while it has not been unequivocally (human
epidemiological experience) established that
DU is a carcinogen the evidence that it is, is
compelling.
It is also likely, from the experience in New
York state (Parrish et al 2008), that chronic
exposure to DU aerosols will result in
incorporation of DU into the body and hence
a risk of cancer.