DR MAHATHIR’S advisers on radiation safety seem to be unaware that there is no scientific consensus on radiation risk from internal emitters (radioactive particles that end up in the human body through inhalation, or ingestion via food and water).

The existing norms for safe thresholds for radiation exposure are derived from quantitative risk models of the International Commission on Radiological Protection, which are largely calibrated against external sources of instantaneous irradiation of large human populations, most notably the long-term follow-up studies of survivors of the Hiroshima and Nagasaki atomic bomb blasts.

Whether these findings are appropriate for assessing the health risks of chronic exposure to low-level ionising radiation from ingested or inhaled internal emitters remains contentious, in particular its micro-dosimetric as well as radiobiochemical aspects.

This was evident in the 2004 report of an independent expert panel convened by the UK government (committee examining radiation risks of internal emitters, Cerrie, para 15, p116 and para 22, p117).

Opinions among the Cerrie members ranged from negligible adverse effects to an underestimation of risk by at least 100-fold.

Internal emitters are very pertinent to Lynas’s accumulated radioactive solid wastes.

As of May 2019, 580,000 metric tonnes of water leach purification waste, containing about 2,000ppm Thorium 232 and lesser amounts of Uranium 238, were visible as open piles in the flood prone premises of Lynas’s rare earths refinery in Gebeng.

If inundated and widely dispersed by floodwaters (or severe storms), this clayey waste when dry can give rise to suspended respirable particulates, or be ingested from contaminated surfaces.

The cabinet decision to allow Lynas to continue operating its refinery for another four years means that we will eventually be saddled with 1 million tonnes of radioactive waste.

The long-term storage facility for 80,000 drums of radioactive waste in Bukit Kledang, from Asian Rare Earth’s Bukit Merah refinery cost Mitsubishi US$100 million (RM418 million), and deprived us of 41ha of land in perpetuity.

Does Lynas have the financial capacity for the construction and long-term maintenance of a secure permanent disposal facility for 1 million tonnes of its waste, now that its preferred option of re-dilution and recycling of its radioactive wastes has been stymied?

Lynas’s radioactive waste in Malaysia is an unwelcome legacy of the incompetence or worse of previous BN administrations.

The new government should not compound this dilemma by allowing Lynas to further multiply its already massive piles of radioactive waste.

* Dr Chan Chee Khoon, Citizens’ Health Initiative