Selection of Approach 2. Format of Standards III. Characterization of the Risks of Radi- ation A. Sources of Radiation B. Health Effects of Radiation C. Risk Assessment ; 1. Uncertainties in Risk Measures -j. Effective Dose Equivalent E. Science Advisory Board Review V.
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Discussion of Source Categories A. Department of Energy Facilities B. Uranium Fuel Cycle Facilities D. Elemental Phosphorus Plants E. Underground Uranium Mines J. Surface Uranium Mines ': K is a measure of the transformation rate of radioactive nuclei at a given time. The customary unit of activity, the curie, is 3. The effective dose equivalent has the same risk for" the model used to derive the weighting , factors as a uniform dose equivalent to all organs and tissues.
A description of the weighting factors used in the calculation , of the EDE is described in detail in the International. Commission on Radiological Protection's Publication No. Other health effects non-fatal cancers, genetic, and developmental are noted separately;. This definition does not include mining operations, operations at waste disposal sites, transportation of any radioactive material in support of these operations, or the reuse of recovered non-uranium special nuclear and by-product materials from the cycle.
In protecting public health with an ample margin of safety under section , EPA strives to provide maximum feasible protection against risks to health from hazardous air pollutants by 1 protecting the greatest number of. Implementation of these goals is by means of a two-step standard-setting approach, with an analytical first step to determine an "acceptable risk" thai considers all health information, including risk estimation uncertainty,. A second step follows in which-the actual standard is set at a level that provides "an ample margin of safety" in consideration; of all health, information,' including the number of persons at risk levels higher than approximately 1 inl milUon, as well as other relevant factors including costs and economic impacts, technological feasibility, and other factors relevant to each particular decision.
Applying this approach to the radidnuclide. A principle that accompanies. Therefore, judgment must be used in deciding how numerical risk estimates are considered with respect to these goals. As discussed below, uncertainties arising. Many of the factors are. A principal aspect of the proposal, and the basis for the proposed decisions on.
Circuit's decision in NRDCv. The Vaiyt Chloride decision required the Adminisn: In the second step, setting an "ample margin of safety", each of the four approaches considers all health risk and other information, uncertainties associated with the health estimates, as well as costs, feasibility, and other factors which may be relevant in particular cases.
The proposal solicited comment on each of the approaches for implementing the Vinyl Chloride decision. The Agency received many public comments on the approaches from citizen's groups, companies and industry trade groups, state and local governments, and individuals. General NESHAP Policy Considerations The purpose of this section is to discuss the appropriate criteria for determining an "acceptable risk" and an "ample margin of safety". In its determination, EPA will consider measures of health risk, and limitations and uncertainties of the risk estimation methods and basic data.
A discussion of these factors follows. Selection of Approach Based on the comments and the record developed in the rulemaking, EPA selected an approach announced hi the notice on benzene standards published on September 14, 54 FR , base'' on Approaches A and C but also incorporating consideration of incidence from Approach B and consideration of health protection for the general population on the order of 1 in 1 million from Approach D.
Thus, in the first step of the Vinyl Chloride inquiry, EPA will consider the extent of the estimated risk were an individual exposed to the maximum level of a pollutant for a lifetime. The EPA will generally presume that if the risk to that individual is no higher than approximately 1 in 10 thousand, that risk level is considered acceptable and EPA then considers the other health and risk factors to complete an overall judgment on acceptability.
The presumptive level provides a benchmark for judging the acceptability of maximum individual risk, but does not constitute a rigid line for making that determination. It is estimated based on the assumption of continuous exposure for 24 hours per day for 70 years. As such, it does not necessarily reflect the true risk, but displays a conservative risk level which is an upperbound that is unlikely to be exceeded. The Administrator believes that an MIR of approximately 1 in 10 thousand should ordinarily be the upper end of the range of acceptability. As risks increase above this benchmark, they become presumptively less acceptable under section Or, the Agency may find, in a particular case, that a risk that includes MIR less than the presumptively acceptable level is unacceptable in the light of other health risk factors.
In establishing a presumption for MIR, ' rather than a rigid line for acceptability, the Agency intends to weigh it with a series of other health measures and factors. These include the overall incidence of cancer or other serious health effects within the exposed population, the numbers of persons exposed within each individual lifetime risk range and associated incidence within a radius around facilities, the science policy assumptions and estimation uncertainties associated with the risk measures, weight of the scientific evidence for human health effects, and other quantified or unquantified health effects.
The EPA also considers incidence to be an important measure of the health risk to the exposed population. Incidence measures the extent of health risk to the exposed population as a whole, by providing an estimate of the occurrence of cancer or other serious health effects in the exposed population. The EPA believes that even if the MIR is low, the overall risk may be unacceptable if significant numbers of persons are, exposed to a hazardous air pollutant, resulting in a significant estimated incidence.
Consideration of this factor would not be reduced to a specific limit or range, such as the 1 case per year limit included in proposed Approach B, but estimated incidence would be weighed along with other health risk information in judging acceptability. The limitation of MIR and incidence are put into perspective by considering how these risks are distributed within the exposed population. This information includes both individual risk, including the number of persons exposed within each risk range, as well as the incidence associated with the persons exposed within each risk range.
In this manner, the distribution provides an array of information on individual risk and incidence for the exposed population. Particular attention will also be accorded to the weight of evidence presented in the risk assessment of potential human carcinogenicity or other health effects of a pollutant.
While the same numerical risk may be estimated for an exposure to a pollutant judged to be a known human carcinogen, and to a pollutant considered a possible human carcinogen based on limited animal test data, the same weight cannot be accorded to both estimates. In considering the potential public health effects of the two pollutants, the Agency's judgment on acceptability, including the MIR, will be influenced by the greater weight of evidence for the known human carcinogen.
In the Vinyl Chloride decision, the Administrator is directed to determine a "safe" or "acceptable" risk level, based on a judgment of "what risks are acceptable in the world in which we live. As described there, the survey developed information to place risk " estimates in perspective and to provide background and context for the Administrator's judgment on the' acceptability of risks "in the world in which we live. Once listed, radionuclides became subject to the requirement of section b l B that EPA establish National Emission Standards for Hazardous Air Pollutants NESHAPs at a "level which in the judgment of the Administrator provides an ample margin of safety to protect the public health from such hazardous air pollutant," or find that they are not hazardous and delist them.
On April 6,, EPA proposed standards regulating radionuclide emissions from four source categories: The Agency simultaneously proposed decisions not to regulate several other categories: In February , the Sierra Club filed suit in the U. EPA was subsequently ordered by the Court to promulgate final standards or make a finding that radionuclides are not hazardous air pollutants and delist them. In October , EPA withdrew the proposed emission standards for elemental phosphorus plants, DOE facilities, and NRC licensees, finding that the control practices already in effect for those categories protected the public from exposure to radionuclides with an ample margin of safety.
EPA, therefore, concluded that no additional requirements were necessary 49 FR , October 31, In the notice, EPA also withdrew proposed standards for underground uranium mines but stated its intention to promulgate a different standard for that category and simultaneously published an Advance Notice of Proposed Rulemaking ANPR for radon emissions from underground uranium mines to solicit additional information on control methods.
EPA affirmed its decision not to regulate the other categories: The Agency also decided to study further the category of phosphogypsum stacks to determine the need for a standard. On December 11,, the U. District Court for the Northern District of California found EPA in contempt of its order to promulgate final standards and again directed that EPA issue final radionuclide emission standards for the original four categories or make a finding that radionuclides are not hazardous air pollutants. EPA complied with the court order by promulgating standards for radionuclides emissions from elemental phosphorus plants, DOE facilities, and NRC-licensees 50 FR , February 6, and a work practice standard for radon emissions from underground uranium mines 50 FR , April 17, On September 24,, EPA promulgated a final rule regulating radon emissions from licensed uranium mill processing sites by establishing work practices for new tailings 51 FR , September 24, On July 28,, the U.
Natural Resources Defense Council, Inc. The Court in Vinyl Chloride concluded that the Agency improperly considered cost and technological feasibility without first making a determination based exclusively on risk to health. In light of that decision, EPA concluded that the standards for elemental phosphorus plants, DOE facilities, NRC-licensees, and underground uranium mines should be reconsidered and on November 16,, moved the D. Circuit Court for a voluntary remand of the challenged decisions.
EPA also agreed to reexamine all issues raised by the parties to the litigation. On December 8,, the Court granted EPA's motion for voluntary remand and established a time schedule for EPA to propose regulatory decisions for all radionuclide. On March 17,, the Court granted a subsequent EPA motion and modified the order to require proposed regulatory decisions by February 28, and final action by August 31, On April 1,, EPA also requested a remand for its standard for licensed uranium mill tailings.
Public hearings were held on April 10, 11,13, and 14, On July 14,, the court granted EPA's request for an extension until October 31, for final action. Sources of Radiation '-' ' - Every day each person is exposed to radiation from a variety of natural and manmade sources. Natural sources of radiation include cosmic rays, radon, and other terrestrial sources. Manmade radiation includes medical and dental X- rays, fallout from above ground nuclear weapons testing and industrial sources.
The earth's atmosphere acts as a shield to cosmic rays, absorbing much of the radiation. People receive a higher dose of cosmic rays at higher altitudes because there is less atmosphere to shield them from cosmic rays. For example, people living in the mountains receive a higher dose than people living at sea level, and people are exposed to even higher levels when flying in an airplane. Terrestrial radiation comes from the small amount, of radionuclides that are naturally present in all matter: Radon is a radionuclide that is produced as a radioactive decay product of the radium which is naturally found in soil.
Radon is always present in the. In addition, radon often gets trapped in homes, leading to even higher estimated health risks. EPA has issued recommendations to homeowners for reducing these risks. This rulemaking deals with sources of radionuclide emissions, including radon, from industrial sources. It is important to note that total background radiation from all sources, including naturally occurring radon, results in a calculated individual lifetime risk of fatal cancer of approximately one in one hundred.
In " most cases, little can be done to reduce most of this radiation exposure which people receive from natural-background. IndustriaLsources of radionuclide emissions in the air include a wide variety of facilities, ranging from nuclear power facilities to hospitals to uranium mill tailing piles.
Industry uses hundreds ,of different radionuclides in solid, liquid, and gaseous forms, emitting different types of radiation alpha, beta, gamma at various energy levels. Industrial , sources of radionuclide emissions fall into two major categories. For'example, hospitals use radionuclides as part of their radiology departments. Since many of the radionuclides they use are gases,.
An example of this is phosphogypsum stacks piles.
These piles of waste material emit radon because radium from which radon is produced by radioactive decay is found naturally in the same soils that are the source of phosphate rock;. Health Effects of Radiation. Different radionuclides will irradiate different parts of the body. Since there is such a strong foundation for quantifying the risk of fatal cancer, EPA's consideration of fatal cancers'is; the principal health consideration in this rulemaking. However, it is important to note that other health effects have also been considered in the rulemaking.
In addition, risk distribution of health effects from radiation from most of the sources considered for regulation show that fatal cancers occur much more frequently thairnon-fatal cancers and cancers generally occur more often than genetic or developmental effects. For sources that emit radon, no genetic or developmental effects, and very few non-fatal cancers are expected.
It is assumed that there is no completely risk-free level of exposure to radiation to cause cancer.
Benzene-induced Cancers: Abridged History and Occupational Health Impact
However, the effects of radiation doses at low levels of exposure can only be predicted by extrapolating from the observed effects at higher doses since we do not have direct evidence of cancer causation at low exposure levels. Some pollutants cause diseases that are unique to the pollutant; for example, asbestos causes asbestosis. Radiation, however, causes some of the same types of cancers, e.
It is assumed that there is no completely risk-free level of exposure for hereditary effects. Based on extensive scientific - evidence, EPA believes it prudent to assume that carcinogens, including radionuclides, pose a risk of health effects even at low levels of exposure. Based on this science policy judgment, EPA calculates health risk. However, the severity of either effect is not related to;the amount' of dose received. That is, once a cancer or an hereditary effect has been induced, its severity is independent of.
Others, however, believe that other models, ' which usually predict somewhat lower risk, provide better estimates. These - differences of opinion have not been resolved to date by studies of the effects of radiation in humans, the most important of which are those of the survivors of the Hiroshima and Nagasaki atomic bombs. Some studies have recently been completed, and others are now underway to reassess radiation dose calculations for the survivors of the Hiroshima' and Nagasaki atomic bombs and to provide improved estimates of risk.
These studies may reduce the uncertainty associated with extrapolation from high doses to low doses. These studies may also resultin an increase of the estimated risk per unit dose. But they will not address the question of whether a threshold exists. EPA is monitoring the progress of this work and will initiate reviews of the risks of. These are termed "niaximum individual risk", "risk distribution", and "incidence".
The exposure estimated is the average daily exposure assuming exposure for 70 years. Individual risk is expressed as an. The maximum individual risk is sometimes called the maximum exposed individual risk. This estimate is based on the fact that the concentration of an emission, and the consequent risk, diminishes with distance from its source.
For radionuclide NESHAP decisions, the practice has been to estimate exposure according to census data on residence locations. The maximum individual lifetime risk is different from average individual risk which is sometimes estimated for sources like public drinking water systems or food in which the concentration of a pollutant and other factors are assumed to be equal at all distribution locations.
Used alone, the measure does not tell how many people may be so affected; it relates only to the risk to the most exposed individual s. A risk distribution estimates how many persons within a certain distance e. Typically, the distribution is given for fold increments,of individual risk. Such a distribution provides the decisionmaker with information on both the individual risk level for those exposed and the number of persons exposed at each level. For NESHAP and other decisions, the Agency has examined risk distributions both as measures of risk and to compare the effects of various strategies for risk reductions across a source category.
In making an acceptable risk decision, one relevant consideration is how many people are exposed at each risk level, e. Similarly, the numbers of persons exposed at various individual risk levels could be an important element in deciding on acceptable risk. The risk - distribution could be used in;similar , ; ways to consider whether an ample margin of safety, exists. It is derived by multiplying.
This number, which provides a lifetime population risk figure, is then divided by 70 years to give an annual fatal cancer incidence estimate. The incidence parameter can be used as an estimate of impact on the entire exposed ' population within a given area by totalling the incidence associated with each increment of individual risk.
Incidence can also be portrayed along with individual risk and population numbers in a risk distribution. Typically, the Agency weighs incidence estimates in conjunction with maximum individual risk or average individual risk estimates. Estimated incidence generally is a particularly informative parameter when looking at aggregate risk from a category of like sources. One feature to take into account whenever it is used is its dependence on the size of the source category. Uncertainties in Risk Measures Each of the thr. These are the estimated response per unit of pollutant concentration e.
Uncertainties exist in estimating each of these elements for a variety of reasons including the fact that the relevant data and our understanding of the biological events involved are not complete. Exposures," 51 FR , September 24, The following is a discussion of methods used to calculate the three parameters, together with a few examples of the uncertainties. Wlien the toxicity data! Nevertheless, important uncertainties enter into, the analysis even when human data is available.
Examples include the fact that human epidemiological studies are often retrospective and measure effects of exposure that occurred many years in: Also, in certain categories of human studies, the studies are often of workers exposed to the pollutant. Worker populations are not representative of the general population with respect to age or sex.
Workers are also generally the healthier segment of the population. When data from animal.. Many of these concern the extrapolation from data collected in animal tests to estimate effects on human's. The extrapolation, ; has to try to account for many factors, such as the equivalent dose for humans: In estimating exposure, the dispersion of a pollutant from a source is usually Standard assumptions are that the population around the -.
The amount of emissions can be derived from sampling and analysis of emissions at the source or from engineering estimates, wi. Thus, it is evident that uncertainty is difficult to quantify. However, the Agency has completed a - preliminary uncertainty. Instead of discreet values, distributions were used for factors having a significant effect" on outcome. The results suggest that the risks calculated represent essentially median values if the receptor remains a that location for 70 years.
Methodology 'To take into account the buildup of radioactivity in the body and ths: In attempting to make these estimates, EPA has tried at all times to give "best estimates" of the radionuclide - - - - concentrations in the environment and individual and population risks. Wherever possible, measured or. Where estimates were used; EPA has feied t category as it now stands.
EPA has sot estimated the: This, is not to say that there is little- or no uncertainty in. EPA's analyses are not-designed' to;-. Many, possible errors in the.. However,, this source of error tends to bs less , important in population estimates, since the analysis integrates individual doses to a large number of people. If one person gets a larger risk due to local dispersion effects, it means that another person is getting less.
Consequently, when the individual risks are summed, local conditions will not cause a serious error in the value for total population risk. In estimating the radiation exposure , to the most exposed individual, EPA assumes that, the person receiving the maximum individual risk lives for a year lifetime at the same site. EPA then makes its best estimate of the risks to that individual. EPA recognizes that most people will not actually live their entire life. Nevertheless, EPA makes this assumption as a matter of policy and does not believe that it diminishes the validity of its risk assessments.
EPA has made tills assumption for several reasons. Use of different assumptions could lead, in some cases,. Risk is not independent of: In addition, due to thefe youthj they generally have a longer tims in which to develop thti cancer caused: If EPA were ta rs? Third, the conservatism of this. The jSrst is the susceptibility of some members of the population to radiation. It is known that childVeis. Radionuclidba are not ike. It is possibls that some of. Radiation risks are compared with other risks and other radiation control recommendations.
EPA should use best estimates and ranges in the specification of risk and provide a detailed ,. EPA agrees, but this is a large task. For the short term, we have performed a sensitivity analysis of the most important parameters using. This longer term effort will take a number of years to complete and will be dependent on the resources available. However, it does not believe that such a complete analysis would change the decisions made in this rulemaking.
The initial decision to iist a substance does not constitute a decision to regulate any particular source category. EPA analyzed numerous studies which indicated that exposure to radionuclides can cause three major types of health.. After considering these health effects, EPA judged that radionuclides cause or contribute to air pollution which "may reasonably be anticipated to endanger public health" and that they should be listed under. That decision was the first step in the regulatory process, arid it was challenged in the current litigation.
As a result, EPA has reevaluated the; decision arid the comments from the public during this rulemaking and has come to the conclusion that the original Usting under section is correct. The first part of the listing decision, the "hazardousness" of fadibnuclides, is unchallenged. The evidence that radionuclides can cause cancer has, if anything, increased since ; see Volume 1 of the BID. While some people haver expressed the view that, even though. Furthermore, as already discussed, EPA assumes radiation to be a non-threshold pollutant. Therefore, EPA reaffirms its ': EPA notes that several sources.
Several are predicted to emit a level resulting in an incidence of. Based on this, it has been suggested'thatEPA should apply a significance test to these sources, and determine that they do not warrant regulation based on the insignificance of the risks presented. EPA applied the significance test of the Supreme Court's pSHA benzene opinion in its prior riilemakings on radionuclides to determine whether each source category warranted regulation. American Petroleum Institute, U. Ruckelshaus, , F. However, EPA believes it is unnecessary to reach this issue at this time since EPA believes that its standards should have no practical effect on the facilities to which such a test might have applicability.
But 'see CAA section d 7 B. The standards would have no practical impact on operations of sources that might be deemed to pose. Discussion of Source Categories The regulatory decisions reached today are based on the risk assessments and other factors available in the rulemaking record. This rule is also based on consideration of information received during the comment period to the rulemaking.
Some facilities conduct imclear energy and weapons research and development, some enrich uranium and produce plutonium for nuclear weapons and reactors, and some process, store and dispose of radioactive wastes. These facilities contain significant amounts of radioactive material and emit radionudides into Ihe air. Other facilities contain large stockpiles of waste ore which emit large quantities of radon. A discussion of those DDE facilities appears as a separate section later in this Preamble.
EPA is considering the two categories separately in this rulemaking because the two categories employ different control methods. Some of the DOE facilities emitting radionuclides are on large sites covering hundreds of square miles in remote locations. Some of the smaller sites resemble' typical industrial facilities and are located in suburban areas. In total, DOE has approximately 30 major sites that emit radlonuclides.
These facilities emit a wide variety of radionuclides in various physical and chemical states. Emissions from various DOE facilities represent many types of radionuclides and both internal and external dose pathways although specific facilities may emit only one or two radionuclides affecting only one tathway. EPA has updated its risk assessment with infonnatioii received during the comment period. EPA has a high jdegree of confidence in the results of this risk assessment. The risk to the most exposed individual is.
DOE facilities axe estimated to cause 0. Table 3 presents example scenarios to show how different emission levels would result in different health risk profiles. The table also presents available estimates of annual incidence and maximum individual lifetime risk for a lower emission level. Decision on Acceptable Risk. As stated earlier, the maximum individual risk Jo any individual is 2. The estimated annual incidence is 0. The results of this analysis may be seen in Table 4.
Based on this very small reduction in incidence, the small decrease in. Requirements of the rule, such as the submission of yearly reports and obtaining prior approval of new construction or modification, assure that DOE facilities will keep emissions at or below an acceptable level insuring an ample margin of safety. The facilities owned and controlled by i DOE. There are 30 major DOE facilities that release radlonucjides into ; the air.
Risk Individual E-2 to E Alternative 1 , baseline , 1M ,, '. Total cancers no more than twice fatal cancsrs. However, wa" cannot quantify the number because detailed demographics have not been obtained. Although the report is based on a calendar year the dose. Because tha thresholds for measurement are much lower than'the standard, under certain circumstances the concentration and potential doses associated with release. Definition of a Facility. A problem in implementing the current standard is the ambiguity associated with the present definition of a facility.
To resolve this ambiguity, the new rule specifies that all the buildings, Distinction Between Construction and Modification, A potential problem resulting from EPA's definition of a facility as all the buildings, structures and operations within a given plant site, is confusion over whether the construction of a hew building is part of an existing facility, is new construction, or is a modification of an existing facility. This rule specifies that the ; construction of a new building is new construction at the facility' and not a modification of the facility.
This includes cases where the modification has the potential to increase emissions above -. However, to reduce unnecessary paperwork, it is appropriate to avoid applications for approval in cases of small changes. Therefore, EPA is promulgating a system under which D. OE facilities will, use CAP to determine the dose to the most exposed indivi3ual due to the modification or new construction. In making the determination of dose for this purpose, DOE must use the. Procedures Approved for Demonstrating: Compliance or other procedures for which EPA has granted prior approval.
These facilities include research and test reactors, hospitals, clinics, the radiopharmacealical industry, low level nuclear waste disposal facilities, and other research and industrial facilities. These facilities are located in all fifty states. The facilities in this category emit a large number of radionuclides.
These radionuclides affect individuals by inhalation, ingestion, ground deposition and immersion pathways. Individual facilities may emit only one or two radionuclides affecting only one or two pathways. There are two types of HLW facilities, management and disposal facilities. The disposal of HLW,.
The management, processing and storage of HLW that occurs at a NRC-licensee is included in the estimate of emissions of the licensee used in. Due to the wide scope of this category, EPA's risk assessment of this source category includes both the largest known emitters and model facilities with model populations.
The estimates of maximum individual risk are based on the assessment of the largest known emitters. The analysis of the largest sources was based on information compiled from previously existing databases and information received from some of the sources themselves. The use of model facilities increases the uncertainty of the risk assessment.
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The estimates of population risks are based on extrapolations from model facilities using census tract data. Frequency distributions do not take into account overlapping sources. The results of this analysis show a maximum individual risk of 1. EPA estimates that this category results in 0.
Although virtually the entire U. Some of the larger NRC- licensees release small amounts of iodine and iodine; these radionuclides can cause thyroid cancer, which is usually non-fatal. The table presents the risk: Facilities Source Category The decision that results from the application of the multifactor approach to the rsHC-licensees and non-DOS Federal facilities source category is described below. EPA then considered the other risk factors in order to make an overall determination on acceptability. Very few people are at risks greater than 1. In addition, there would be an estimated annual incidence of approximately 0.
After examining these factors, the Administrator concludes that baseline emissions are acceptable for this source category. The results of this analysis may be seen in Table 6. EPA's risk assessment indicates that no reduction in incidence would occur and only a small reduction of the MIR wojild occur if reduction of current emissions to Alternative IITevels were required.
This means that small reductions in the emissions of a few licensees have little, if any, effect on the mcaber of health effects, both fatal and non-fatal, in ihe population. Based on the very small reductions in the risks to public health and the costs of achieving Alternative II, EPA has determined that Alternative I protects the public health with an ample margin of safety. EPA has decided to continue regulation of this category to insure that the current levels of emissions are not increased. There are about 6, NRC material licensees: Radiopharmaceutical manufacturers and users,7 sealed sources manufacturers, research re- actors, industrial and university laboratories, and low-level waste disposal facilities.
E-2 to E-i '. E-3 to E-2 E-4toE Alternative I baseline 1. While the level of health protection achieved under the NRG standard is generally comparable to that required by EPA's rule, the two standards are very different in form, and the means of demonstrating compliance with each standard impose significantly different regulatory requirements.
The basic issue is whether these different regulatory requirements will discourage the use of radioisotopes in medical and experimental therapies. In addition, NRG has raised the issue of whether regulation of its licensees under a Clean Air Act standard provides any additional public health benefits. EPA has expressed similar concerns in past proceedings on this regulation.
In its Federal Register notice of February 6. However, in recognition of the serious nature of these concerns, and the need to further investigate and resolve these matters, EPA has concluded that it should treat the comments and information filed by NIH and NRC as petitions for reconsideration of the standard with respect to the range of issues raised by NRG and NIH, and EPA is granting reconsideration. Comments should be submitted in duplicate if possible to: After considering the information received, and other available information pertaining to these issues, EPA will issue a decision on the need for further rulemaking on the standard in subpart I.
Uranium Fuel Cycle Facilities 1. Introduction Uranium Fuel Cycle UFC facilities are the facilities used in the conversion of uranium ore to electric power. These facilities are licensed by the NRC. Uranium fuel enrichment facilities are not included in this category because they are included in the DOE facilities source category. Reprocessing plants are not included. If a new one were to be opened in the. However, all releases from these facilities air, water and direct gamma radiation] are covered under the Uranium Fuel Cycle Standard, 40 CFR part In the past, the Administrator decided not to regulate this category under section , because he determined that the AEA standard protected public health with an ample margin of safety.
EPA's decision not to regulate this category is one of the issues in the current litigation. Estimates of Exposure and Risk EPA's risk assessment for this category is the combination of the results of the assessments of the different types of facilities included in this category.
The source term for emissions from uranium mill tailing piles is estimated for operable mills using NRCs methodology. Fugitive dust emissions from a tailing pile are assumed to be a function of meteorological conditions wind, rainfall, temperature , ore composition, particle size and other factors.
Meteorological and population data are based on actual mill sites. The assessment of the two uranium hexafluoride conversion plants. The assessment for fuel fabrication plants is based on reported emissions and census population distributions. The emission estimate for nuclear power plants is based on actual releases from operating plants. Population data is taken if om NRG reference populations.
Assessments consider effects of multiple reactors at a site, but not the overlap of multiple sites. The results of the analysis show that the most exposed individual receives a dose associated with an increased risk of fatal cancer of 1. There is a predicted incidence of 0. Virtually the entire U.
Table 7 presents example scenarios to show how different emission levels would result in different health risk profiles. The table presents the risk estimates at baseline in terms of. EPA then considered the other risk factors in order to make an overall decision on acceptability. After examining these factors, the Administrator has determined that the baseline risks from UFC facilities are acceptable. The facilities thai convert uranium ore into electric power.
They include operating urani- um mills nonradon emissions , uranium hexafluor- kfe conversion plants, fuel fabrication plants, nu- clear power reactors. About facilities make up this category. Alternative I baseline t. Tne facilities that convert uranium era into electric power. E-8 to E-5 teSSE Total cancers no more than twice fatal cancers. There are eight 5 operational, 3 standby elemental phosphorus plants located in four different states.
However, most of the emissions come from two plants in Idaho. Due to the types of radionuclides emitted by these plants, virtually all the dose is received by the lung through the inhalation pathway causing an increased risk of lung cancer. This risk can be controlled through the use of a standard which directly limits emissions of polonium control measures which limit polonium also limit emissions of lead There is no need to write dose standards. Elemental phosphorus plants are currently regulated by a NESHAP that limits their emissions to no more than 21 curies of polonium annually.
Estimates of Exposure and Risk EPA's risk assessment of elemental phosphorus plants is a site-by-site assessment of operating and standby plants, based on monitored data and throughput. Changes in the risk assessment since the proposal are the result of corrected meteorological data. Maximum individual risks were assessed at actual residences or at a location m in the predominant wind direction. The location of nearby populations was taken from census tract data. According to the assessment,.
EPA estimates that the most exposed individual receives a lifetime fatal cancer risk of 5. There is an increased incidence of 0. Table 9 presents example scenarios to show how different emission levels would result in different health risk profiles.
Benzene-induced Cancers: Abridged History and Occupational Health Impact
As stated earlier, the maximum individual risk to any individual is 5. This is higher than the presumptively safe level. After examining these factors, the Administrator has determined that the risk level represented by the baseline is unacceptable. This equals the level that is presumptively safe. E-6 to E-5 ,.. Alternative I baseline 5. Fabric filters on the two largest plants. High energy scrubbers on all othet plants. In addition to reexamining all the health-related factors discussed above, EPA has also examined the cost, scientific certainty, and technological feasibility of control technology, necessary to lower emissions from elemental phosphorus plants.
The results of this analysis may be seen in Table A comparison of the, two alternatives indicates that in absolute terms, a very small reduction in incidence would occur, from 0. EPA examined these very small reductions in risks, and the relatively large costs of achieving Alternative III, arid has determined that Alternative H protects the public health with an ample margin of safety.
Implementation The current NESHAP for elemental phosphorus plants required each plant to either conduct an initial test on its emissions or get a waiver from testing. After this original report no further testing was required, unless plant f operations were changed significantly. EPA plans to continue'this system, without the waiver provisions.
Plants will be required to monitor their operations continuously and keep records of the results of their monitoring onsite for five years. Plant owners will have to certify on a semiannual basis that no changes in operations that would require new testing have occurred. Although the report is based on a calendar year the emission limit applies to any year, i. Coal-Fired Utility arid Industrial Boilers: Introduction , This category covers electrical utility and industrial boilers which emit the radionuclides naturally present in coal.
Coal contains only minute amounts of radionuclides. This category is being considered because large boilers bum large quantities of coal and are so widely dispersed throughout the nation that the radionuclide emissions are estimated to cause 0. Emissions from coal-fired bailers are presently regulated under National Ambient Air Quality Standards for particulate matter.
Estimates of Exposure and Risk EPA's risk assessment of coal-fired boilers is based on extrapolations of estimated radionuclide emissions based on actual particulate emissions with model populations. Estimates of emissions are from the reference " facilities with the largest emissions.
Further information was received from a recent. EPA assumed that the entire U. EPA estimates that the maximum individual risk is 2. Table 11 presents example scenarios to show how different emission levels would: The table presents the risk estimates at baseline in terms of: Application of Decision Methodology to Coal-Fired Boilers Source Category The decision that results from the application of the multifactor approach to the coal-fired boilers source category is described below. As stated earlier, the maximum individual risk to any individual is 2. The estimated annual incidence within 80 km is 0.
Almost everyone in the U. Therefore, EPA concludes that the baseline risk level is acceptable. Over 1, electrical utility and large industrial boilers release the small amounts of radionuclides naturally found in coal along with the non-radioactive particufatesj Maximum individual risk lifetime. Risk incidence 'EE-1 E-3 to E Alternative 1 Baseline , 2. Retrofit would yield additional health benefits due to reductions in particulate emissions.
Decision on Ample Margin of Safety. In addition to reexamining all the health-related factors discussed above, EPA has also examined the cost, scientific certainty, and technological feasibility of control technology necessary to lower emissions from coal- fired boilers. Alternative I, baseline emissions, was compared with Alternative II, which would require. The risk is very evenly distributed among the population. The costs of Alternative n are extremely large. EPA examined the small risks presented by coal-fired boilers and the very large costs of achieving Alternative II, and determined that the current level of emissions represents an ample margin of safety.
The NSPS provides assurance that the risks from coal-fired boilers will be reduced over time. Therefore, EPA has determined that current levels of radionuclide emissions from coal-fired boilers represent a level of risk that protects the public health with an ample margin of safety. Introduction Management and storage operations for high-level nuclear waste, spent fuel and transuranic waste are addressed in the categories for DOE facilities and NRC-licensed and non-DOE Federal facilities described above.
This category addresses facilities constructed and dedicated to long term disposal of such materials pursuant to regulations to be promulgated at 40 CFR Site characterization studies for the first such repository are being conducted by DOE and currently center on Yucca Mountain, Nevada. Population data was taken from U. Although the decision on Yucca Mountain's acceptability as a disposal site has not yet been made, EPA has analyzed the Yucca Mountain site in order to incorporate site specific information into the analysis.
The reason that the emissions and risks are so low is the nature of the disposal operations. Most material will be brought to the site already sealed and buried below ground.
CARCINOGENESIS BIOASSAYS
Normal operations preclude any significant air emissions. Table 14 presents the risk estimates at baseline in terms of estimated annual fatal cancer incidence, maximum. Application of Decision Methodology to the High Level Waste Source Category The decision that results from the application of the multifactor approach to the HLW disposal facilities source category is described below.. As stated above, the individual risks from HLW disposal facilities are very small, 7X10"8, much less than the 1X10" 4 benchmark. In addition, there would be 0. The emissions and risk levels are so low that it was not necessary to evaluate any alternatives.
The Administrator determines that the estimate of emissions from disposal of HLW represents a level that will protect public health with an ample margin of safety. Operations involving the - management, processing or storage of high-level waste, the operations from which an increase in emissions are more likely to occur, are regulated under NESHAPS controlling emissions from NRC-licensees, uranium fuel cycle facilities and DOE facilities.
Disposal operations involve burying sealed containers of radioactive material, operations from which emissions are unlikely to occur. Therefore, EPA believes that there is no reason to expect that emissions to air would significantly increase, and, since the expected emissions are so low, no NESHAP is needed. Facilities designed to dispose of high level nuclear waste. There are no currently operat- ing facilities. A geological repository is being con- sidered for Yucca Mountain, Nevada. Baseline emissions are estimates of expected emissions. J Maximum individual risk lifetime.
Facilities designed to dispose of high evel nuclear waste. E-2 to E-1 '. Total cancers no rnors than twice fatal cancers. Radon Releases from Department of Energy Facilities 1. Some of these facilities have large stockpiles of radium-containing material. Because this material has a high radium content it emits large quantities of radon. Radon emission estimates were mostly measured values provided by DOE or estimated from measured radium concentrations in the wastes.
The meteorological data were taken from nearby stations and" populations are based on U. DOE facilities cause an estimated 0. Catechol has been used as an antiseptic, in photography, and in dyestuffs. Catechol has been shown to have strong promoting activity in mice, and alone induces forestomach hyperplasia, generally a few papillomas of the forestomach non-glandular , and adenomatous hyperplasia and adenocarcinomas of the glandular stomach in near all rats. Used an antioxidant in the rubber industry, as a developing agent in photography, and as an intermediate in the manufacture of rubber and food antioxidants and monomer inhibitors, hydro-quinone products are also used as depigmenting agents to lighten skin.
In mice, thyroid follicular cell hyperplasia was increased males: Increases of anisokaryosis, multinucleated hepatocytes, and basophilic foci occurred in the livers of male mice. Mononuclear cell leukemia in female rats was increased: In low-dose male mice liver tumors were marginally elevated: Hydroquinone made available to rats and mice of both sexes at 0. Hepatocellular adenoma was enhanced in male mice.
Squamous-cell hyperplasia of the forestomach epithelium was higher in mice of both sexes given hydroquinone, but no increase in tumor development was observed. Thus, hydroquinone caused kidney tumors in male and possibly in female rats and mice, leukemia in female rats, thyroid follicular cell hyperplasia in mice, and liver tumors in male and female mice. The remainder is used to produce an assortment of products: For two years rats and mice of each sex were given drinking water containing 0, 2,, or 5, ppm phenol.
No other carcinogenic response was observed in rats or mice. In other studies, phenol given orally with benzo a -pyrene produced sixfold increases in malignant tumors of the forestomach over BaP given alone. Scientific evidence indicates that multiple mechanisms are likely to contribute to benzene-induced leukemias and cancers in other target organs; whether these include individual or co-mechanisms for the individual metabolites remains to be ascertained.
Increasing information lends further credence that metabolites of benzene are primarily responsible for its carcinogenic activity. Phenol, to a lesser extent, and hydroquinone are associated individually with inducing leukemia in animals, and we might opine in humans as well. One wonders what would be the result s if the two chemicals were tested together; that is, whether these findings would be more or less potent than those for benzene or either of these metabolites alone. Catechol causes forestomach and stomach tumors in animals, whereas benzene causes forestomach tumors but does not cause stomach tumors.
Some of the other carcinogenic effects of benzene may be due to combinations of the metabolites or to others not yet evaluated for carcinogenic activity. At the same time, carcinogenic concordance in target sites between animals and humans need not be sacrosanct. Typically in animals there are more tumor sites identified simply because more pathology is done on animals than on humans.
Meanwhile, epidemiology might best broaden the organ scope for future studies. The clear findings of cancers in animals resulting from exposures to benzene and to arsenic , and to all other known human carcinogens that have been tested in animals, confirm and validate once again the value of long-term animal bioassays for identifying potential cancer risks to humans. Interestingly most of these claims are based on supposition and not data regarding either the exact mechanism in animals or the lack thereof in humans.
A key to reducing damage from all carcinogens, whether identified in animals or in humans or in both mammalian species, centers on reducing exposures. The author thanks Peter Infante and Rick Irwin for reviewing and offering valuable comments on this paper, and extends appreciation to Joe LaDou and Sandy Lovegrove for all their crucial help and understanding. National Center for Biotechnology Information , U.
Int J Occup Environ Health. Author manuscript; available in PMC May Author information Copyright and License information Disclaimer. See other articles in PMC that cite the published article. Abstract Benzene-induced cancer in humans was first reported in the late s. Open in a separate window. Catechol Naturally occurring in fruits and vegetables, present in cigarette smoke, and an industrial chemical, catechol is used to make insecticides, perfumes, drugs, and polymerization inhibitors. Hydroquinone Used an antioxidant in the rubber industry, as a developing agent in photography, and as an intermediate in the manufacture of rubber and food antioxidants and monomer inhibitors, hydro-quinone products are also used as depigmenting agents to lighten skin.
Acknowledgments The author thanks Peter Infante and Rick Irwin for reviewing and offering valuable comments on this paper, and extends appreciation to Joe LaDou and Sandy Lovegrove for all their crucial help and understanding. The past suppression of industry knowledge of the toxicity of benzene to humans and potential bias in future benzene research. Multiple-site carcinogenicity of benzene in Fischer rats and B6C3F1 mice.
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