Assessment of Risks from Combined Exposures to Radiation and Chemicals
What are we doing?
We are investigating whether combined exposures to ionising radiation and genotoxic chemicals (any toxic chemical that acts by damaging DNA) is potentially more hazardous than exposure to either of these agents alone. We are also investigating whether the effects of combined exposures could be predicted correctly for risk assessment purposes.
Why are we doing this?
We know from historical accounts and eyewitness testimony that some British nuclear test veterans were exposed to high levels of the insecticide DDT, as well as fuel oils and industrial chemicals, some of which can be carcinogenic (can cause cancer) depending upon the amount and route of exposure. There are concerns in the nuclear test community about possible exposure to ionising radiation during their military service. This raises the question of whether any test veterans received combined exposures of radiation and chemicals.
There is evidence that the combined effects of exposure to ionising radiation and smoking increases the risk of lung cancer compared to exposure to either of these agents alone. For example, a large study that combined data from a number of studies on European populations (Darby et al, 2005) showed that there is a substantial increase in the risk of lung cancer in smokers in areas where there are higher levels of the natural radioactive gas, radon. It is known that there is a mixture of carcinogens present in cigarettes. However, the combined effects of radiation and mixtures of carcinogens are not fully understood and this is the subject of ongoing research.
What does this research involve?
Cells will be cultured (grown) in small, sterile dishes, and exposed to carefully prepared mixtures of genotoxic chemicals and then irradiated with different types of ionising radiation. This approach allows any potential combined mixture effects to be calculated.
A commonly observed effect in experiments like this is the formation of micronuclei (a micronucleus is a small nucleus in the cell, plural micronuclei). This is a consequence of ionising radiation breaking chromosomes.
The first experiments will be performed using standard non-human cells called CHO-K1 cells. These cells are commonly used for studies of this type and so our results can be compared with similar studies. This work will then progress to a human cell culture model.
What impact might our research make?
This research will improve our knowledge of the risks presented by radiation exposures to individuals in real-world exposure scenarios. However, as with all experimental work, care must be taken when extrapolating conclusions from experiments with cells to a human being.
References: Darby, S. et al (2005) Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies, BMJ Vol. 330, Issue 7485, pp. 223-225. [Online] https://www.bmj.com/content/330/7485/223
Researcher Finlay Smith supervised by Professor Andreas Kortenhamp and Dr Rhona Anderson