Press Release

Table of Contents

Acknowledgements

Main findings

Recommendations

I. Introduction

II. National Primary Drinking Water Regulations – Radionuclides
A. Bone dose estimation in ICRP 2
B. Bone dose estimation, present-day dose conversion factors
1. Bone doses according to FGR 11
2. Bone doses according to FGR 13

III. Conclusions

IV. Costs

V. Estimating the impact of residual radioactivity

VI. Other risks and radionuclides

References

VI. Other risks and radionuclides

New scientific work on radiation protection is currently emerging, for instance in relation to (i) protection of the embryo/fetus and infant, (ii) non-cancer effects of exposure to certain radionuclides, (iii) potential synergistic effects of exposure to certain chemicals, such as hormonally active chemicals, and exposure to radiation, (iv) the need for protection of key non-human species and ecosystems, and (v) the synergisms indicated for certain effects between the heavy metal toxicity component of uranium and its radiotoxicity. However, these are still emerging areas of concern, where the risks are not quantitatively well established. How such risks are to be considered in the context of a review of drinking water MCLs will be considered in a future IEER report.

Recent developments in radiobiology and health effects research have increased understanding of radiation doses during fetal development. They indicate that non-cancer health effects resulting from fetal exposure to radiation could be very important. For instance, ICRP 90 emphasizes that the central nervous system is especially vulnerable during a certain period of fetal development:

…[B]iological systems with a high fraction of proliferating cells show high radiation responsiveness. High rates of cell proliferation are found throughout prenatal development…Development of the central nervous system starts during the first weeks of embryonic development and continues through the early postnatal period. Thus development of the central nervous system occurs over a very long period, during which it is especially vulnerable. It has been found that the development of this system is very frequently disturbed by ionising radiation, so special emphasis has to be given to these biological processes.⁴⁰

A variety of end points (disease outcomes) are at issue, from central nervous system development to cancer to birth defects to increased risk of miscarriages. Further, these end points raise the issue of the combined effects of other pollutants with radiation more insistently that ever before. For instance, one might ask about the potential for non-linear effects caused by exposure to both lead and radiation or mercury and radiation. One might also ask about the combined effects of exposure to endocrine disrupting chemicals and radiation in relation to a number of end points. These are areas still in a relatively early stage in the science compared to the understanding of radiogenic cancer induction. For these areas, which concern non-cancer end points as a result of fetal exposure, for instance, the conversion of the scientific data in publications such as ICRP 88 and ICRP 90 into regulations for health and environmental protection will take considerable time.⁴¹ The EPA has not even published the necessary guidance documents as yet.

Recent research, much of it done at the Armed Forces Radiobiology Research Institute, pursuant to concerns about the health effects of depleted uranium, points to a surprising variety of harmful health effects of uranium. A recent literature survey by IEER summarized the situation as follows:

The understanding of the risks of cancer due to radiation exposure from depleted uranium and kidney damage due to its heavy metal properties has expanded greatly in recent years. In addition, evidence is amassing that raises serious concerns regarding the impact of chronic exposure to DU in relation to a number of other health issues. Studies in humans and animals have shown that uranium can concentrate in the skeleton, liver, kidneys, testes, and brain. In addition, rats implanted with DU pellets have also shown uranium concentrating in the heart, lung tissue, ovaries, and lymph nodes among other tissues. Research, primarily but not exclusively conducted since the 1991 Gulf War, indicates that exposure to uranium may be

Mutagenic
Cytotoxic
Tumorigenic
Teratogenic
and Neurotoxic, including in a manner analogous to exposure to lead.

Additionally…some research has also provided indications that there may be a synergistic effect between the heavy metal aspect of exposure to uranium and its radioactive effects…Current research conducted at the Armed Forces Radiobiology Research Institute (AFRRI) indicates that "[i]n the case of DU, cells not traversed by an alpha particle may be vulnerable to radiation-induced effects as well as chemically-induced effects." Additional work at the AFRRI has also shown that depleted uranium can cause oxidative DNA damage and thus provides the first indication that uranium's radiological and chemical affects might potentially play both a tumor initiating and a tumor promoting role.⁴²

In other words, uranium may be a kind of radioactive lead, with serious health effects arising both from its heavy metal toxicity and its radioactivity. Should these risks be proven to be substantial, there may be a need to include new limits in the National Primary Drinking Water Regulations relating to the combined radioactive and heavy metal toxic effects of uranium.

There are also a variety of other issues associated with the potential interaction of hormonally active chemicals with radiation, and particular certain radionuclides, like iodine-129, which concentrates in the thyroid and crosses the placenta. The development of certain cancers, like breast cancer, is linked to hormonal systems, possibly to hormonally active chemical pollutants, and to radiation. Hence the issues associated with health protection in regard to certain cancers are likely to be much more complex.

Finally, there are issues that were once recognized but that appear to have been forgotten or ignored in the context of protection of public health from radiation. Consider the following passage from ICRP 2 that occurs in the context of a discussion of bone doses and the calculations that are the subject of this report:

Certainly, if a major portion of the hematopoietic system were irradiated, e.g., concurrently from the spleen-seeking Po²¹⁰ and from the bone-seeking Ra²²⁶, the biological damage would be greater than if only a part of it were irradiated. It has been shown that in some cases a synergistic effect results when several organs of the body are irradiated simultaneously.⁴³

Some of these synergistic effects are already implicit in the estimates of risk made from Hiroshima/Nagasaki survivors (since they received whole body radiation — i.e., all organs were irradiated). However, others involving internal deposition and that selectively target certain organs may have more complex effects. This indicates that it is important to maintain regulations in the form of dose limits to maximally exposed organs in regulations relating to protection of public health, such as the National Primary Drinking Water Regulations (40 CFR 141), Environmental Radiation Protection Standards for Nuclear Power Operations (40 CFR 190), and Environmental Radiation Protection Standards For Management And Disposal Of Spent Nuclear Fuel, High-Level And Transuranic Radioactive Wastes (40 CFR 191). At the present time, there is still a significant amount of scientific work that remains to be done in a variety of areas before this framework can be changed into a better one from the point of view of health, environment, future generations, and the economy.

Consideration of changes in radiation protection in the medium- and long-term, that would take into account emerging scientific and risk issues such as those discussed in this section, is needed for a variety of reasons, some of which are mentioned above. However, this will be a complex and difficult task which must be done with due deliberation. It will also likely go far beyond safe drinking water standards. At the present time, the safety and protection of water resources from irreversible contamination with alpha-emitting, long-lived transuranic radionuclides as a result of ongoing activities by the Department of Energy cannot be allowed to be deferred to the longer, more comprehensive social, economic, and health discussion related to the protection of health from radioactive and toxic pollution. It must be considered as part of the EPA's 2006 review of standards for radionuclides in drinking water. A maximum contaminant level for plutonium that is 100 times too lax based on the intent and letter of the Safe Drinking Water Act must not be allowed to persist.

Footnotes

⁴¹ ICRP-88, 2002; ICRP-90, 2003.

⁴² Makhijani and Smith 2005, pages 9-10. Typos corrected.

⁴³ ICRP-2, 1959, page 14, emphasis added.