The linear no-threshold (LNT) model and the ALARA principle have served as the conceptual and operational foundations of the global radiation protection framework for many decades.
The LNT model is a risk estimation framework that says any amount of ionising radiation, no matter how small, carries some risk of causing harm, especially cancer. In other words, there is no threshold below which radiation is considered completely risk‑free. And the risk increases linearly with dose.
ALARA, short for “as low as reasonably achievable”, is the operational philosophy of radiation protection. ‘Reasonably’ is the most important condition. The philosophy balances safety with feasibility, cost, and societal need, and its aim is to improve continuously, including better shielding, administrative procedures, and training.
Thus in practice ALARA aims to reduce unnecessary exposure using engineering controls and encourages a safety culture.
Unfortunately, when these principles are misapplied, as they have often been, they create a baggage of woes. The International Commission on Radiological Protection (ICRP) and other stakeholders are realising that modern radiological protection requires a different approach.
ICRP actions
At present, the ICRP is modernising its latest (2007) recommendations. Over 25 dedicated ICRP task groups have been undertaking a comprehensive revision of the entire system to address several issues to fill the gaps. However, the agency has yet to provide a target year: perhaps later this decade, not imminently. The International Atomic Energy Agency will also update its 2014 Basic Safety Standards using the ICRP’s inputs and publish it for universal acceptance.
But it seems not everyone is prepared to wait. On January 12, the U.S. Department of Energy (DOE) “eliminated” ALARA from its directives and regulations, departing significantly from long‑standing national and international practice.
“The DOE’s decades of nuclear facility operating experience confirms that DOE’s mission to foster nuclear innovation and advanced nuclear technologies could be met more effectively if the current radiation framework were reformed,” a Department memorandum said in a follow-up to President Donald Trump’s orders.
Critics have argued that the shift appears politically motivated and relies on non‑peer‑reviewed internal reports, and risks undermining worker protection, public trust, and regulatory coherence. Indeed, the U.S is now at odds with international bodies such as the ICRP, the U.N. Scientific Committee on the Effects of Atomic Radiation, the World Health Organization, and the Nuclear Regulatory Commission (NRC), all of which continue to rely on LNT as a precautionary basis for radiation protection. In 2021, the NRC had decisively upheld the LNT model to prescribe radiation safety standards. Will they change as well?
In spite of recurring scientific debate, no large‑scale, high‑quality epidemiological or mechanistic evidence has emerged to justify replacing LNT with alternative dose-response models, including hormesis (which says low dose radiation is okay). While hormesis remains biologically plausible, its variability across populations, ethical limitations, and lack of reproducible human data render it unsuitable for regulatory use.
Unpredictable future
The ICRP hasn’t shown any indication that the dose limits to workers and members of the public will be revised. There may be a renewed effort to accept a low dose level below which no regulation is required.
Finally, critics have emphasised the importance of public perception. Even if some experts believe higher dose thresholds could be justified scientifically, the optics of abandoning ALARA and LNT are problematic. For those living near nuclear facilities, the change may look like a lowering of safety standards rather than a refinement of scientific assumptions.
Without broad scientific consensus, transparent communication, and meaningful public engagement, critics fear that the policy shift will deepen mistrust, fuel opposition to nuclear projects, and make it harder to secure social license for existing and future facilities. Public communication on nuclear issues will continue to be an onerous task.
Possible evidence of cancer and non-cancer effects at low doses have also appeared in more recent studies, such as the ongoing ‘Million Person Study’. Another study of nearly a million young individuals revealed that a few of them may suffer blood related cancers at very low doses (Nature Medicine, November 9, 2023). We can no longer ignore them, and expect the ICRP will take note of such work as well.
Finally, scientists must face the blame for not communicating with the public after arriving at a consensus on contentious issues using the best available science. If experts start fighting among themselves, what will the non-experts do? Whom will they trust?
For its part, India has been at the forefront of complying with the internationally accepted radiation protection practices and must continue to stay there.
K.S. Parthasarathy is former secretary, Atomic Energy Regulatory Board.
Published – February 18, 2026 06:15 am IST
