Regulation under Uncertainty: Use of the Linear No-Threshold Model in Chemical and Radiation Exposure

The catastrophic consequences of events such as the Hiroshima and Nagasaki bombings have made the harmful health effects of exposure to high doses of radiation abundantly clear. But what about exposure to low doses of radiation—for example, radiation from X-rays and CT scans? For decades, government regulators have used a risk assessment model known as the linear no-threshold (LNT) model to inform their rulemaking. This model presumes that low-dose exposure to chemicals and radiation is always harmful. In fact, according to the model, there is no threshold to toxicity—exposure to even a single molecule results in proportional and irreversible harm. This implies that setting regulatory standards to ever lower exposure levels will always appear desirable, especially when cost considerations are ignored.

Relying on updated research and incorporating lessons from economic theory, a new study for the Mercatus Center at George Mason University explains why using the LNT model as the default risk assessment model is inadequate at best and harmful to public health at worst. Regulatory agencies should consider alternative risk assessment models when investigating the risks and benefits of low-level exposure to chemicals and radiation.

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