Comments upon the proposed National
Drinking Water Regulations; Radionuclides;
Federal Register April 21, 2000 (Volume 65, Number 78)]
[Proposed Rules] [Page 21575-21628] (pdf download)
Mallinckrodt Research Professor of Physics
Cambridge, MA, 02138
Tel: 617 495 3387
Home tel: 617 332 4823
FAX: 617 495 0416
E Mail: WILSON@HUHEPL.HARVARD.EDU
Address, phone and E mail for identification only
(1) Overall purpose of Regulations of Radionuclides
Any document should discuss the purpose. This in particular applies to regulatory documents. I cannot find a clear justification for the proposal that properly derives from the fundamental purpose - the protection of human health. The absence of a justification traceable back to this fundamental purpose makes the whole proposal hard to understand and potentially VERY dangerous. I proffer a possible justification with some comments derived therefrom:
In order to protect the public from the possible adverse effects
radiation upon health, the
International Commission on Radiological Protection (ICRP) has
recommended that radiation
doses to the public from anthropogenic activities be kept to below
mrems/year average. Recognizing that there are fluctuations, ICRP
suggested that this will easily be achieved if
individuals are allowed to be accumulate a dose of 500 mrem/year.
recently in ICRP
(Publication 60, paragraph (192) they recommend that the dose rate
limit for members of the
public be an effective dose of 100 mrem/year. "In special
circumstances, a higher value can be
allowed in a single year, provided that the average over 5 years
not exceed 100
mrem/year." For a single source (such as a low-level radioactive
disposal facility, the
ICRP permits something in the range of 10 to 25 mrem/year. Even
mrem/yr would only
amount to an approximate doubling of the natural background. It is
consensus of many expert
committees that the effect on health of an exposure to this level
lifetime would not lead to
a directly measurable effect because any effect would be small.
Studies such as those summarized in the reports of the United Nations Subcommittee on the Effects of Atomic Radiation (UNSCEAR) show that anthropogenic activities are on average far lower than this, and the main component is medical X rays. Indeed anthropogenic radiation doses other than medical X rays are smaller than the place-to-place fluctuation in natural background to which little attention is given. Any new regulation, or modification of an old regulation, must be justified against these simple facts.
(2) There is an important and increasing realization that performance -based regulation and risk-based regulation are superior to prescriptive regulation. Thus after a regulation to keep doses at site boundary to less than 10 mrem per year (or better 25 mrems per year as noted in (2) above) has been promulgated it should be open to the entity being regulated on how to meet it. Prescription by EPA is unnecessary at best and usually counterproductive. Although the EPA has properly requested comment on the method of implementation, it is only a request on what they should prescribe. This section on implementation of the proposal is therefore outdated prescriptive regulation and must be reconsidered.
(3) There is an unproven postulate that the effects of radiation on people are linear at low doses. This has led to a recommendation that doses be reduced to a level As Low As Reasonably Achievable (ALARA). The Nuclear Regulatory Commission after a 2 year long public hearing discussed what this means in practice and came up with a recommendation that doses be reduced if they can be done for a sum of $1,000 per man.rem now updated for inflation (and corrected for political correctness) to $200,000 per person.Sievert. This should be the standard against which any regulation must be compared. If an entity can (and does) emit radiation or radionuclides which can be reduced, then a regulation can force him to spend that much money. Conversely, if a regulation demands a higher cost than this it should be changed.
The 1996 Amendments to the Safe Drinking Water Acts, perhaps for the first time other than FIFRA, granted EPA discretionary authority, if it determines that the technically feasible level does not justify the costs, to adjust the standard to a level that maximizes health risk reduction benefits at a cost that is justified by the benefits. In the document under review this is only discussed as an afterthought and not an integral part of the proposed standard itself. It is noteworthy that if a linear, no threshold, dose response is assumed, with a slope as recommended by the usual bodies of about 1/30 fatal cancers per Sv to about $6,000,000 per statistically calculated life. This is close to the recommendation of the EPA itself in its proposed guidelines for economic cost/benefit analyzes of summer 1998, that costs should be incurred at $4,000,000 per "statistical life". The NRC proposal is more definite and workable because it sidesteps the unknowable issue of whether or not there is a threshold. I find, regrettably no discussion at all about this. EPA should have a clear and definite reason for deviating from the $ 200,000 per person Sievert, for public exposures, discussed by NRC. Specifically unless the new proposal costs less than $200,000 per person.Sv integrated average exposure, it should be abandoned or modified. I see no calculation in the proposal that justifies this expenditure.
(4) Various risk levels are calculated and presented in the present proposal. However there is no clear statement of the conservatisms and uncertainty in these calculations. I suggest that the tables of risks are incomplete and misleading unless and until such a listing of uncertainties is placed in close proximity to the numbers. The main uncertainty, of course is whether or not the linear-no threshold-theory applies at low doses or whether there is a threshold. I can find this stated nowhere in the document. In responding to a public comment EPA defend using a 95th percentile upper limit. They argue that taking an upper 95th percentile water intake of 2 liters per day is preferable to taking the average figure of 1 liter a day. But here EPA is inconsistent. While for an individual taking an upper 95th percentile may be appropriate (IF CLEARLY STATED) it is completely wrong for a population for which the cancers are calculated. For that calculation the average is needed.
(5) EPA should be moderately consistent in its proposals for carcinogenic pollutants in water. A recent proposal (http://www.epa.gov/ogwdw000/ars/proposalfs.html May 24th 2000) for regulation of arsenic in drinking water suggests a level of 5 ppb of arsenic in the water. Arsenic is unequivocally a human carcinogen. The effect of arsenic in water at a level of 500 ppb (only 10 times the present EPA-allowed level of 50 ppb) is producing a catastrophe in Bangladesh that exceeds in magnitude the Chernobyl disaster by a factor of over 10 and maybe 100. The estimated risk of arsenic at 5 ppb in drinking water (also based upon a linear-no-threshold model) is about 2 x 10E-3. - ten times the risks talked about in the present proposal. It could be argued (improperly since EPA is supposed to regulate materials based on their hazard not their origin) that arsenic is a naturally occurring element - but uranium is a naturally occurring element also. Anthropogenic activity can increase (by digging wells) or decrease (by filtering) exposure. This suggests that a concentration level that gives a calculated risk of 2 x 10E-3 is the proper rule for all carcinogens, including radionuclides, in drinking water. Alternatively EPA could a very clear, logical argument why it is sensible for the EPA to propose (in the same month!) a lower risk limit for uranium than for arsenic!