§ Lord Jenkin of Roding asked Her Majesty's GovernmentWhat action they are taking following the article inNature (Vol 421 pp 691-2) which argues that the dose response to most toxins, including ionising radiation, is hormetic, which means that the body's response to low doses is almost always beneficial rather than harmful. [HL2571]
§ Baroness AndrewsThe hormesis theory described in the article inNature is highly controversial. There is little evidence to support claims that exposure to low doses of toxic chemicals such as cadmium, dioxin, or 12WA polycyclic aromatic hydrocarbons, nor ionising radiation, has a beneficial health effect.
The approach adopted by government departments/ agencies when assessing the health risks arising from toxic chemicals is based on the assumption that for most chemicals there is a dose below which no harmful effects would be expected; that is, that there is a threshold dose. This is used in estimating safe levels of exposure. However, in the specific case of chemicals that affect the genetic material of the cell (DNA), and which may then go on to cause cancer, the prudent assumption is made that there is no threshold, and any exposure may increase cancer risk, albeit this increase may be very small at low dose levels. This is in line with the advice from the relevant, independent expert advisory committee, the Committee on the Carcinogenicity of Chemicals in Food, Consumer Products and the Environment (COC).
A similar approach is taken with regard to ionising radiation, since this may produce cancer by affecting DNA. Again this is in line with advice from the National Radiological Protection Board, and from the Committee on the Medical Aspects of Radiation in the Environment (COMARE).
The COC is currently in the process of updating its guidance on the risk assessment of chemical carcinogens and the Nature article has been referred to it for consideration in its deliberations.