As science has enabled humans to measure substances and phenomena at ever lower doses and units of measure, a strange fear has been imposed upon some people. Before those tiny quantities could be measured, those same people were blissfully ignorant of the substances that made up their world. They did not worry about coming in contact with bacteria, mercury, lead, arsenic, tritium, radon, or pesticides if they were present in quantities that made them impossible to detect.
Sometimes that inability to measure caused some dangerous situations because the substances, even though they could not be measured with the technology available at the time, were present in high enough quantities to harm humans and other living creatures. Devising methods of detecting previously invisible items was a great boon to public health.
Unfortunately, as science has enabled detections and measurements at ever smaller concentrations it has not completely kept up with determining the health effects of substances. As experimenters began to ratchet down their measurements to use prefixes like nano (10^-9) and pico (10^-12) to report results, the underlying health assumption has been a linear, no threshold (LNT) dose response or the precautionary principle that assumes that anything that causes a bad reaction at high doses will cause a similar, but lower intensity reaction at any measurable dose.
Under those assumptions, if a substance like DDT or mercury is proven to be dangerous to birds, humans and rats at high concentrations, then it is assumed have some danger at any concentration – all the way down to zero. Because the LNT and the precautionary principle do not ever reach a stage of zero risk, they lead to rules and regulations that expect contaminants to be completely eliminated from the environment.
The same assumption has been applied to radiation doses attributed to nuclear energy programs – since we know that radiation can cause death or other harmful effects at high doses, regulators have assumed that it always poses some danger and should be eliminated, even down to dose rates that are tiny fractions of normal background radiation. This assumption might have made some sense at a time when measuring incredibly small concentrations or dose rates was impossible, but it departs from real life experience once the levels approach a certain level.
There is a growing body of evidence for a dose response called “hormesis” for nearly every contaminant or physical phenomenon that we are able to measure. Hormesis refers to the fact that substances that are poison at high doses are often beneficial at much lower doses. Too much iron can kill you, not enough makes you far more susceptible to a variety of ailments. Radiation doses like those found very close to unshielded radioactive material can be deadly; the doses measured at shielded nuclear power plants, or at waste disposal sites are significantly lower than those found in the therapeutic spas that people have been frequenting for hundreds of years because they seemed to have beneficial effects.
Even Lawrence Solomon, the primary force at Energy Probe, a Canadian organization with which I rarely agree because they have a long history of fighting nuclear energy and promoting natural gas, has noticed that there is a growing quantity of peer reviewed science pointing to hormetic effects. He recently wrote a comment piece for National Post titled Lauding low doses that described hormesis and recommended a book titled Hormesis: A Revolution in Biology, Toxicology, and Medicine by Mark P. Mattson and Edward J. Calabrese, both PhD credentialed researchers at respected universities (Johns Hopkins University School of Medicine and University of Massachusetts in Amherst respectively). The book is published by Humana Press; it is most definitely not aimed at the general public with its Amazon discounted price tag of $150 from a list price of $189. This is apparently a serious academic work written for a target audience of other researchers in the field.
Hormesis has some rather staggering economic implications because the linear no threshold dose response assumption and the precautionary principle have driven the cost of equipment design, operations, and clean-ups as regulators have applied ever stricter rules and limits.
In the case of radiation dose rates, the EPA has imposed a radiation protection standard on radioactive material storage sites of just 15 mrem per year for 10,000 years and the NRC has imposed a radiological criteria for unrestricted use of 25 mrem per year with a stated goal of ALARA (as low as reasonably achievable).
(Aside: As most nukes can attest, the NRC has a far different standard for “reasonable” than most people would have when it is applied to the cost of efforts to reduce radiation exposure or dose rates from contamination. Historically speaking, NRC regulators have not considered that it is “unreasonable” to expect licensees to spend tens of millions of dollars to reduce a constructed potential annual dose from 25 mrem down to 20 mrem. Recent experience at Vermont Yankee has indicated that some regulators do not think that it is “unreasonable” to spend tens of millions to find and eliminate a barely measurable quantity of tritium from the environment, even if there is no evidence of potential harm. End Aside.)
For comparison to those strict standards, normal background doses from natural sources of radiation are approximately 250-300 mrem per year and vary by factors of 5-10 around the world. The strictly applied standards have added tens of billions of dollars to the cost of clean-up at former nuclear plant sites, weapons related sites, and at proposed waste storage sites.
The resistance to accepting the possibility of hormesis has been quite strong among the professional groups who impose the LNT assumption. Even my spell checker does not recognize the word. However, the science continues to develop a greater and greater acceptability as the evidence piles up that Paracelsus was right when he said “All things are poison and nothing is without poison, only the dose permits something not to be poisonous.” When our regulators and radiation protection professionals recognize that fact and realize that ALARA rules don’t make any sense below a certain level, the world will be a healthier place with a better allocation of resources to attack real problems.