COMMENTS: Radon-222, W-99-08Comments Clerk Water Docket (MC4101)U.S. Environmental Protection Agency401 M Street, SWEast Tower BasementWashington, D.C. 20460
To Comments Clerk:
I am writing in regard to the EPA's proposed rule for radon-222 in drinking water [National Primary Drinking Water Regulations; Radon-222, Notice of Proposed Rulemaking, Federal Register, Vol. 64, No 211, November 2, 1999]. The 1996 amendments to the Safe Drinking Water Act mandate that the EPA set a standard in year 2000 based on a National Academy of Sciences (NAS) risk assessment [42 USC § 300g-1(b)(13)(B)(i)] as well as the "the best available, peer reviewed science"[ 42 USC § 300g-1(b)(3)(A)(i)]. According to the EPA's own proposed regulation and the National Academy of Sciences (NAS) Risk Assessment on Radon [National Research Council, Risk Assessment of Radon in Drinking Water, (Washington DC: National Academy Press, 1998)], radon in drinking water poses an extremely small theoretical public health risk.
The fact that drinking water risks are very small is acknowledged by the NAS risk assessment, which notes most radon-related cancer fatalities result from inhalation of radon that seeps into buildings from underlying soil and rock. As a result, concentrations develop in buildings beyond what we experience outdoors. In addition, some radon is released from drinking water, but NAS estimates that water only contributes 1/10,000 to the indoor air concentration and that eliminating this amount (or a portion thereof as the regulations would do) won’t make much of a difference. The NAS’s "best estimate" is that all indoor air radon exposures cause 19,000 lung cancer deaths annually, while radon from drinking water might lead to only 160 fatalities.
Accordingly, the EPA has stated that it would like to set the drinking water maximum contaminant level (MCL) at the stringent level of 300 pCi/L and set an alternative maximum contaminant level (AMCL) at 4000 pCi/L. When states, localities, or community water systems implement an EPA-approved "multimedia mitigation plan" (MMM), they can meet the less stringent AMCL. With a 300 pCi/L standard, EPA notes that most states will likely develop MMMs plans and seek EPA approval – focusing on radon found in indoor air – which is the "real" area of risk. In fact, the agency explicitly states:
EPA believes the extensive statutory detail enhanced on multimedia mitigation illustrates a congressional preference for cost-effective compliance through the AMCL/MMM program approach. EPA notes that the equal or greater reduction required to be achieved through the AMCL/MMM option would be diminished as the MCL approaches the AMCL of 4000 pCi/L and that fewer states and CWS [community water systems] would select this option. Further, the AMCL/MMM would be eliminated entirely if the MCL were set at the AMCL [National Primary Drinking Water Regulations; Radon-222, Notice of Proposed Rulemaking, Federal Register, Vol. 64, No 211, November 2, 1999].
Hence, the EPA justifies its proposal in part because it will enable the agency to promote the MMM approach. On this point, the EPA requests comments from those who believe that the agency should instead set an MCL at a level approaching 4000 pCi/L, asking commenters to provide a justification under the SDWA. The following offers one such response.
The EPA’s reading of congressional intent is curious. The statutory detail on MMMs is not all that extensive. In fact, it includes several paragraphs and is not designed to give EPA’s drinking water office an excuse to promote MMMs, thereby entering into a new area of regulation: regulation of indoor air via approval of state MMMs. Instead, it is designed to lend some flexibility, if the EPA sets a stringent standard that places too great a burden on community water systems. Hence, the EPA should set the standard based on its ability to reduce drinking water risks alone – not based on the potential to use that standard to regulate indoor air. The law states: "If the maximum contaminant level for radon in drinking water promulgated pursuant to subparagraph (E) is more stringent than necessary to reduce the contribution to radon in indoor air from drinking water to a concentration that is equivalent to the national average concentration of radon in outdoor air, the Administrator shall, simultaneously with the promulgation of such level, promulgate an alternative maximum contaminant level for radon that would result in a contribution of radon from drinking water to radon levels in indoor air equivalent to the national average concentration of radon in outdoor air" [42 USC § 300g-1(b)(13)(F)]. Hence, the law is silent on the value of AMCLs and leaves open the possibility for the EPA to set an MCL that is even higher than the current one – eliminating the need for an AMCL. In addition, the House and Senate Conference report explanatory statement does not even mention the radon provision, let alone the MMM provision [House Report, 104-741].
Both the original House and Senate bills and their conference reports do not even include the MMM provisions. In fact, the provisions in those bills and the report language clearly indicated that the original desire was to discourage the EPA from setting a needlessly stringent standard. The House bill simply set dates for the radon rule and required the EPA to "consider" radon mitigation programs – but did not include MMMs [See House Report 104-632 Part 1; H.R. 3604, Section 108, 104th Congress]. The Senate bill and report language did not include MMMs and would have preempted the EPA from setting a standard below 3000 pCi/L unless three conditions were met. One of those conditions mandated that EPA focus on risks from ingestion of drinking water, rather than indoor air, which is the exact opposite of what MMMs are designed to do [See Senate Report 104-169, p. 43, p.128-129].
The MMM provision appears to represent compromise language that was added late in the process and reflects the desire to make the standard more flexible for community water systems, not to create an indoor radon program. After all, the main purpose of the SDWA is designed to regulate drinking water, not air quality. And given expressed congressional concern about overly stringent standards, the EPA should not use the MMM program to justify setting a stringent rule. Instead, the rule should be based on promoting drinking water quality using sound science while considering the costs and benefits to the public.
On the science, the NAS risk assessment claims that radon in drinking water may cause 160 fatal cancers per year – 1-2 percent of all indoor radon related cancers. Another 20 fatal cancers – this time stomach cancer – supposedly result from ingesting radon in drinking water. Of note, the NAS risk assessment indicates that the risks from ingestion could be zero "depending on the validity of the linear no-threshold dose response hypothesis." In any case, these estimates indicate that EPA’s radon rule could save few lives if any. The EPA says that it would save 62 lives, but a critical look at the underlying science reveals that even that number may be inflated.
Furthermore, the EPA should consider some qualifications that the NAS makes regarding its cancer fatality estimates. The NAS risk assessment notes that most of these deaths would occur among smokers – who may be more susceptible to cancer when exposed to high levels of radon. However, it is not even clear how much of a role radon might play in such cases or whether smoking is the primary factor, particularly among those exposed to what is a relatively low-level radon gas in homes. Appendix A to the NAS risk assessment notes:
Incomplete understanding of the combined effect of these two carcinogens remains a key uncertainty in assessing the risk of indoor radon, and the consequences of synergism between radon and smoking in making quantitative risk estimates have not been universally appreciated. The underground miners who were participants in the epidemiologic studies that are the basis for currently used risk estimates were primarily smokers, and epidemiologic data from the miners' studies have not provided a precise characterization of the lung-cancer risk arising from radon exposure in never smokers [ National Research Council, Risk Assessment of Radon in Drinking Water, (Washington DC: National Academy Press, 1998), p. 225].
To complicate matters further, NAS estimates rely almost exclusively on data from studies assessing the impacts of high-level occupational radon exposures to miners to assess risks from low-level exposures to the public from indoor air. Such reliance is based on the fact that indoor risks are so low (if they exist at all) that these studies cannot detect them. Hence, such studies will likely never provide valuable information on indoor risks. Accordingly, the NAS risk assessment notes that the committee did not do a new analysis for the inhalation risk, but instead developed an average based on three studies: BEIR IV, NIH, and BEIR VI [Lubin, JH, et al, Radon and Lung Cancer Risk: A Joint Analysis of 11 Underground Miners Studies 94-3644 (Bethesda MD: National Institutes for Health, 1994); National Research Council, Health Risks of Radon and Other Deposited Alpha-Emitters (BEIR IV) (Washington DC: National Academy Press, 1988); National Research Council, Health Effects of Exposures to Radon (BEIR VI), (Washington, DC: National Academy Press, 1999)]. All of these studies rely largely on data from miners who were exposed to high levels of radon and many of whom smoked. The 1999 BEIR VI report highlights this very point noting that that studies of radon in homes have:
not produced a definitive answer, primarily because the risk is likely to be very small at the low exposure encountered from most homes and because it is difficult to estimate radon exposures that people have received over their lifetimes. ... Since a valid risk estimate could not be derived from only the results of studies in homes, the BEIR VI committee chose to use the lung-cancer information from studies of miners, who are more heavily exposed to radon, to estimate the risks posed by radon exposures in homes [National Research Council, Health Effects of Exposures to Radon (BEIR VI), (Washington, DC: National Academy Press, 1999)].
But the problem is the miner studies really only show one thing: there are elevated cancer levels among miners who smoked heavily and were exposed to high levels of radon as well as nitrogen oxides and mineral dusts in the mines. Neither the NAS nor the EPA has been able to establish that low-level radiation in homes causes cancer to nonsmokers or even to smokers.
Still, the agency and NAS use a linear model – assuming that relatively high risks from high-level exposure translate into lower (yet still significant) risks given low-level exposure. Yet there is evidence that radon has a threshold under which it is not only safe, but beneficial. Scientists have found that low-level exposure to radon can actually reduce cancer rates because low-level exposures enable our bodies to create defenses against the substance, much the way we build immunities to biological diseases [For example, see B.L. Cohen, "Test of the Linear-no Threshold Theory of Radiation Carcinogenesis for Inhaled Radon Decay Products," Health Physics, vol. 68 no. 2, 1995, pp. 157-174]. Both the EPA and the NAS fail to consider this growing body of evidence on thresholds related to radon and low-level radiation in general. Given that the SDWA mandates that the EPA and the NAS consider the "best available, peer reviewed science," the EPA should consider this information and reevaluate the MCLG, and therefore, the MCL for radon.
In the final analysis, the only definitive conclusion from the NAS Risk Assessment and the EPA proposal is that radon risks from drinking water are extremely small if they exist at all. The NAS and the Agency have failed to consider all the best science – particularly the information that would enable the agency to set a less stringent, more reasonable standard. And finally, the EPA is attempting to justify the rule in part based upon what it incorrectly deems as a mandate to enter into regulation of radon in indoor air. For all these reasons, the EPA’s proposed radon standard does not follow the intent or mandates in the law, and it promises to impose needless burdens on the public for potentially zero public health benefits. The public would be better served it the EPA would leave the standard at the existing level or set a more reasonable standard by reexamining the NAS findings and all the "best-available" science.
Director of Risk and Environmental Policy Competitive Enterprise Institute