At the Foreign Correspondents’ Club of Japan on May 30, 2019, Tun Dr Mahathir made perhaps unscripted remarks about ‘spreading out’ the radioactive solid wastes from Lynas’ rare earths refinery at Gebeng, presumably to re-dilute its radioactive content closer down to baseline (background) radioactivity levels.
From an epidemiological (population health) perspective, this is not advisable. Here’s the reason why.
The 2006 US National Academy of Sciences’ Biologic Effects of Ionizing Radiation VII (BEIR VII) report is an authoritative source which endorses the linear no-threshold (LNT) model of a linear and causal relationship between ionising radiation and human cancer risk.
The LNT model accepts that radiation at all levels confer proportionate risk of cancer. It explicitly excludes a threshold below which radiogenic cancer risk disappears. In plain language, cancer risk doesn’t vanish to zero, even at very low (close to zero) doses of radiation.
Epidemiologists and radiation safety specialists calculate the expected number of radiation-caused cases of, say leukaemia, by multiplying the radiation dose by the expected number of leukaemia cases per unit dose for a defined population size, using the dose-response relationship of the LNT model.
The BEIR VII report has done that for the US population.
The current allowable radiation exposure endorsed by the International Commission on Radiological Protection is 1 mSv per year above natural background levels, for the general public. The average dose worldwide from natural background radiation is approximately 2.4 mSv per year.
The BEIR VII report estimates that a lifetime cumulative dose of 100mSv would cause an additional 100 leukaemia cases from a population of 100,000 males. In the absence of radiation exposure, the lifetime tally of leukaemia cases (from other causes) would be 830.
In other words, the lifetime risk of leukaemia is increased by about 12 per cent as a result of lifetime radiation doses accumulated from exposures at levels close to the current allowable limits. The corresponding figures for females are 70/ 590, i.e. a similar 12 per cent increase in risk of leukaemia.
For this reason, it is little comfort to know that if Lynas’ radioactive solid wastes are recycled as ingredients for road base, cement and other construction materials, fertilisers, Condisoil, etc and ‘spread out’, communities nationwide will be incrementally exposed to low-level radiation at doses comparable to background exposures.
It makes little difference if you dilute the radioactive content of Lynas’ solid wastes by 10-fold, and then expose 10x more people to the more voluminous (diluted) wastes.
The net increase in (leukaemia) cases among the exposed populations will be the same in both scenarios.
What’s important for safer disposal of radioactive wastes, from the population health perspective, is sequestration, not dilution and dispersal.
Western Australia’s Mines, Petroleum, Energy and Industrial Relations Minister Bill Johnston conceded as much when he said: “Generally speaking, the best place for contaminated material is where it comes from, which in this case would be in the [Mt Weld] mine void [i.e. sequestered away from the possibility of human exposures], but we are not going to take mine waste back from overseas”.
We urgently need Tun Dr Mahathir’s recalcitrant streak.
Chan Chee Khoon is a consultant and health policy analyst. He is a member of the Citizen’s Health Initiative.
- This is the personal opinion of the writer or publication and does not necessarily represent the views of CodeBlue.
