Presentation on theme: "Is depleted uranium a carcinogen? Keith Baverstock PhD Department of Environmental Science University of Kuopio Finland."— Presentation transcript:
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? Yes, probably widespread in Iraq, much more limited in Balkans Human exposure?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. Evidence in animals?Yes, published evidence but limited. 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 “bio- available” 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 (hypoxanthine- guanine 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 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.