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More Information on Multiple Chemical Sensitivity

MCS is a rather poorly understood illness. MCS has no generally accepted definition or proved physiological mechanism, yet it is gaining recognition. Broadly speaking, physicians have two theories about what causes MCS: either it is chemicals or it is basically psychological phenomena (Hileman, 1991, p. 30, 31).

Many patients say their problems began either after an overwhelming chemical exposure, such as a job-related chemical spill, or after a new, chronic, medium-level exposure, such as moving into a new house with significant emissions of volatile organic chemicals from the building materials or beginning to work in a new building, often one with poor ventilation. Thereafter, the symptoms seem to wax and wane with low-level chemical exposures, and when exposures are avoided, the symptoms diminish or disappear altogether. In an informal survey of some 6,800 persons claiming to be chemically sensitive, conducted by a patient group called the National Foundation for the Chemically Hypersensitive, nearly half of the patients said their illness started after a pesticide exposure (Hileman, 1991, p. 29).

As a group, people allegedly suffering from MCS have a large number and range of symptoms that they attribute to chemical exposures. The complaints are physical and mental and involve nearly all the systems of the body. The most common symptoms include respiratory problems; headache; fatigue; flu-like symptoms; mental confusion and short-term memory loss; gastrointestinal tract difficulties; cardiovascular irregularities; skin disorders; genitourinary problems; muscle and joint pains; irritability and depression; and eye, ear, nose, and throat problems. Some individuals experience only one symptom, but most have more than one (Hileman, 1991, p. 28). People who have been diagnosed with MCS have been divided into four categories: 1) industrial workers; 2) occupants of "tight buildings," including office workers and schoolchildren; 3) people who live in communities where the air and water are contaminated by toxic chemicals; and 4) other individuals exposed to chemicals in consumer products, drugs, and pesticides (Hileman, 1991, p. 30). Except for industrial workers, females appear to outnumber males in all of these groups. The levels at which these effects occur widely vary. Patients must have symptoms or signs related to chemical exposures at levels tolerated by the population at large. Reactions to such well-recognized allergens as molds, dusts, and pollen are not included. MCS differs from allergy in that patients with MCS have some mental and physical symptoms that allergy patients do not have (Meggs, 1992, p. 203).

Although there are widely differing opinions on the causes of MCS, physicians and researchers do agree on one point. There is a need for double-blind, placebo-controlled studies of patients' responses to airborne chemicals. Indeed, there are no reported results from well-designed studies of that kind in the medical literature, which is why the debate on MCS has gone on until now without a clear resolution (Hileman, 1991, p. 40; Barinaga, 1991, p. 1558). In conjunction with these types of studies, a uniform data base should be established to reflect detailed information about patients' sensitivity to foods, chemicals, and drugs; their dietary, smoking, and medication histories; and psychological screening information (Hileman, 1991, p. 40).

Information on Ammonia
Ammonia is a commonly recognized respiratory tract irritant. If the indoor air quality is poor (e.g., if there is a low level of ventilation), a very low concentration will cause irritation. In terms of individual susceptibility, the concept of worker tolerance is recognized but is poorly understood. A person's tolerance may change with the development of an inter-current illness such as viral respiratory infection or with multiple chemical exposures. In some cases, symptoms might develop after years of working in a particular environment. In persons who develop specific susceptibility, symptoms might occur at concentrations below threshold limits, for example, levels not readily detected as irritants by most people (Ron, 1992, p. 529).

Information on Other Potential Indoor Chemicals
Formaldehyde is a common indoor contaminant and is found in some particleboard, plywood, pressboard, and paneling; some carpeting and carpet backing; some furniture and dyed materials, urea formaldehyde foam insulation (mid-1970s dated buildings); some household cleaners and deodorizers; combustion gas, tobacco, and wood; some glues and resins; tobacco smoke; cosmetics; and permanent-press textiles. VOCs (e.g., alkanes, aromatic hydrocarbons, esters, alcohols, aldehydes, and ketones) are also a common source of indoor contaminants. VOCs are commonly found in solvents and cleaning compounds, paints, glues and resins, spray propellants, fabric softeners and deodorizers, combustion, dry-cleaning fluids, some fabrics and furnishings, stored gasoline, out-gassing from water, some building materials, waxes and polishing compounds, pens and markers, and binders and plasticizers (Ron, 1992, p. 1245-1246).

More Information About Asthma

Asthma is characterized by a widespread narrowing of the airways resulting from an increased responsiveness of the trachea and bronchi to various stimuli. Asthma is chronic with episodic manifestations of symptoms, usually sneezing, breathing difficulty, fatigue, cough, and tightness in the chest. Persons with asthma constitute approximately 2% to 3% of the general population in the U.S.

Studies have shown that since the early 1970's, the prevalence of asthma, or the total number of people with asthma, has been increasing in the U.S. and other countries. Nearly ten million Americans are reported to have asthma, and experts in the field suggest that many other people have the disease but have not yet been diagnosed and treated (American Lung Association, 1990).

Between 1980 and 1987, the prevalence of asthma reported in the U.S. increased by nearly thirty percent, from 3 percent to 4 percent of all Americans. Increases were reported in every age and racial group, and among both males and females. About the same number of men and women have asthma, but under the age of 20 the prevalence rates are higher among males than females. Blacks have had slightly higher rates than whites (4.4 percent compared to 4 percent of whites) (American Lung Association, 1990).

Little is known about risk factors that are related to the prevalence, severity, and persistence of asthma. Apart from occupational asthma, the environmental factors which have been shown to induce asthma symptoms include the following: 1) allergens such as those produced by cockroaches, house dust mites, mammals and birds, molds and fungi, pollen, and food and drugs; 2) irritants such as sulfur dioxide, ozone, nitrogen dioxide, and mixtures of pollutants, present in the ambient air, consisting of ozone, carbon monoxide, and nitrogen dioxide; and 3) climactic factors such as temperature (more specifically, sudden changes in temperature), humidity, and temperature inversions. In addition, exercise and emotional stress have been shown to induce asthma symptoms as well as to increase the symptoms when the factors above are also present (Goldsmith, 1991. p. 102). Most communities around the world in which the temporal patterns of asthma have been studied show a definite rise in asthma attacks and symptoms in the fall season, and many show increases in the spring (Goldsmith, 1991, p. 104).

The most common allergic diseases caused by indoor allergens are allergic rhinitis, sinusitis, asthma, and allergic skin diseases (dermatitis). The symptoms commonly associated with allergy and allergic reactions are conjunctivitis (red, irritated eyes); rhinitis (a stuffy, runny nose; or "hay fever"); and bronchitis (cough and congestion) (Pope and Burge, 1993, p. 2). Additional exposure to the sensitizing allergen leads to a mild, moderate, or severe allergic reaction, depending on the amount of exposure. Exposure to nonallergens that irritate the respiratory tract (e.g., environmental tobacco smoke) can promote the development of allergic reactions and disease.

It has been predicted that one out of five Americans will experience allergy-related illness at some point during their lives and that indoor allergens will be responsible for a significant share of these cases. As such, indoor allergens are a major public health problem. The level of allergen exposure in the home (or elsewhere) influences the risk of becoming sensitized to indoor allergens, the risk of developing an allergic disease, and the severity of the allergic disease. Because of this, relationship allergy can play a key but sometimes unrecognized role in triggering asthma (Pope and Burge, 1993, p. 4,6).

Americans spend more than 90% of their time indoors in environments that are increasingly airtight and that often contain sources of allergens, such as dust mites, fungi, house pets, rodents, cockroaches, and certain chemicals. Increased incidence, prevalence, and severity of asthma and other allergic diseases are associated with exposure to these agents and constitute major components of the public health problems related to indoor air quality in the U.S (Pope and Burge, 1993, p. 1).

Occupational asthma is a condition, characterized by asthmatic symptoms described above that develops after the inhalation of a substance or material that a worker manufactures, uses directly, or is exposed to incidentally at the work site. The following occupations carry the risk of occupational asthma from the sources indicated: animal breeder/handler (animal antigens); baker (flour, insects, mite debris); butcher (polyvinyl chloride (PVC) fumes, causing "meat wrapper's asthma" when exposed to both emissions from hotwire cutting of PVC film and from thermal activation of price labels); hairdresser (sodium/potassium persulfate); coffee processor (green coffee beans); detergent enzyme worker (proteases); farm workers (animal antigens, vegetable dusts); food additive worker (tartrazine); grain handler (grain, insect debris dust); laboratory worker (animal antigens); leather worker (formalin, chromium salts); lumber and woodworking (wood dusts); milling (flour, insects, mite debris); paper products manufacturer (natural glues); pharmaceutical worker (penicillin, ampicillin); plastics industry worker (diisocyanates --TDI, HDI, MDI; anhydrides--PA, TCPA; diethylene tri-& tetramine); platinum refiner (platinum salts); printer (vegetable gums); veterinarian (animal antigens); and vegetable oil production worker (flaxseed, cottonseed castor bean) (Ron, 1992, p. 393-396, 399, and 414-417).

Additional information can be found at your local American Lung Association. The American Lung Association affiliates nationwide offer various asthma health education programs and materials for children, parents, adults, health professionals, school personnel, and the general public (American Lung Association, 1990).

More Information About Breast Cancer

Risk factors for breast cancer include being older than 40 (risk increases with age); having a personal or family history of breast cancer; early age at menarche; late age at menopause; never giving birth; first giving birth after age 30; and higher education and SES. Neither ingestion nor inhalation of the types of chemicals found on RMA has been associated with the development of breast cancer. There is mounting evidence that a high-fat diet can increase the risk of breast cancer. An injury to the breast may call a woman's attention to a tumor that is already there but cannot cause breast cancer (American Cancer Society, Inc., 1993, p. 11; and American Cancer Society, Inc., 1987, p. 1).

Breast cancer is still the most common form of cancer among American women, accounting for more than 30% of all cancers in women. One in nine American women will develop breast cancer by age 85. About 46,000 American women will die in 1994 because of breast cancer. Only lung cancer causes more cancer deaths among women (American Cancer Society, Inc., 1987, p. 1). From the late 1940s to the late 1980s, breast cancer incidence rates for females rose 56%, with most of the increases occurring during the last decade; they have leveled off since 1987 (DeVita, Hellman, and Rosenburg, 1993, p. 159). Some of the recent rise in rates is believed to be due to marked increases in mammography utilization, allowing the detection of early-stage breast cancers, frequently before they would become clinically apparent. Other reasons for a long-term increase in breast cancer are not yet understood (American Cancer Society, Inc., 1993, p. 11).

The warning signs of breast cancer include breast changes that persist, such as a lump, thickening, swelling, dimpling, skin irritation, distortion, retraction, scaliness, pain, or tenderness of the nipple. Although breast cancer is thought of as a woman's disease, about 300 men die of the disease each year (American Cancer Society, Inc., 1993, p. 11 and American Cancer Society, Inc., 1987, p. 1).

More Information About Throat Cancer

Cancer of the throat is usually grouped under the category of Oral Cancer. Oral cancer has not been associated with exposure (via ingestion or inhalation) to the types of chemicals found on RMA. Risk factors include cigarette-, cigar-, or pipe-smoking; use of smokeless tobacco; and excessive use of alcohol. An estimated 29,800 new cases were expected for 1993. Incidence is more than twice as high in men as in women and is most frequent in men over age 40.

Oral cancer is defined as cancer affecting any part of the oral cavity, including the lip, tongue, mouth, and throat. Dentists and primary-care physicians have the opportunity during regular checkups to see abnormal tissue changes and to detect cancer at an early, curable stage. Warning signals for oral cancer include a sore that bleeds easily and doesn't heal; a lump or thickening; or a red or white patch that persists. Difficulty in chewing, swallowing, or moving the tongue or jaws often occurs in later stages of oral cancer (American Cancer Society, Inc., 1993, p. 18).

More Information About Stomach Cancer

Stomach cancer occurs approximately twice as often in men as women, and, in the U.S., the incidence is higher among black men than among white men. The incidence of stomach cancer increases with advancing age, beginning in the forties and reaching a peak incidence in the seventies in men and a slightly later peak incidence in women (DeVita, Hellman, and Rosenburg, 1993, p. 819).

Prior gastric surgery, as well as gastric atrophy and gastritis, are associated with an increased risk of developing stomach cancer. Risk factors related to occupation include work in the rubber industries and in coal mines. Smoking tobacco is also a risk factor (DeVita, Hellman, and Rosenburg, 1993, p. 820 and Ron, 1992, p. 328).

Increased use of refrigeration and better food preparation have helped decrease the incidence of stomach cancer, since food preservatives are often high in nitrates (Wilson et al., 1991, p. 1250). Studies have shown that consumption of raw vegetables, fruit, citrus fruit, and high-fiber bread, or a diet rich in vitamin A and C, lowers the risk of developing stomach cancer (DeVita, Hellman, and Rosenburg, 1993, p. 820).

More Information About Bladder Cancer

Smoking is the greatest risk factor for the development of bladder cancer, with smokers experiencing twice the risk of nonsmokers. Smoking is estimated to be responsible for approximately 47% of the bladder cancer deaths among men and approximately 37% among women. People living in urban areas and workers in the organic chemical, rubber, paint, and especially dye industries also are at higher risk. Recent data indicate that there could be a familial or genetic predisposition to bladder cancer development, but more studies are needed to verify this possibility (American Cancer Society, Inc., 1993, p. 18 and DeVita, Hellman, and Rosenburg, 1993, p. 1052, 1053).

Overall, the incidence rate of bladder cancer is four times greater among men than among women and is higher in whites than in blacks. The latency period, or the amount of time that it may take for the cancer to develop, has been observed to be 16 to 22 years (DeVita, Hellman, and Rosenburg, 1993, p. 1052). The warning signal of bladder cancer is blood in the urine, usually associated with increased frequency of urination (American Cancer Society, Inc., 1993, p. 18). Very few data exist on the factors that play a protective role against the development of bladder cancer are available, although it has been suggested that milk and vitamin A ingestion may prevent the development of bladder cancer (DeVita, Hellman, and Rosenburg, 1993, p. 1052, 1053).


The Rocky Mountain Arsenal Public Health Assessment was released for public comment on January 17, 1995. The comment period was scheduled to end on February 21, 1995 but the state of Colorado and a citizen requested an extension of the comment period. An extension was granted and the public comment period then closed on March 23, 1995.

Comments were received from The U.S. Fish and Wildlife Service, Tri-County Health Department, Shell Oil Company, Rocky Mountain Arsenal, Colorado Department of Public Health and Environment, City and County of Denver, and four members of the public. The U.S. Environmental Protection Agency had no written comments on the assessment. In summary, 10 sets of comments were received.

The comments received were reviewed and grouped into either a "specific comment" category or into a category of "general issues" or related questions raised by more that one respondent. For those "general issues" the respondents comments were summarized and paraphrased by ATSDR for brevity and clarity. A single ATSDR reply was then written for those "general issue" comments. The following "general issues" were raised: 1) State of Colorado versus Federal Regulatory Standards, 2) Health Studies and Health Outcome Data, 3) Wildlife and Other Potential Foodchain Issues, 4) Onpost Contamination, 5) Offpost Contamination, 6) Past Exposures and the ATSDR Hazard Ranking Scheme, and 7) Bias in Acceptance of Reports.

The "specific comments" that were received either identified new information; questioned specific sentences or paragraphs in the text or tables; or suggested additions or correction to improve the clarity, completeness, or accuracy of a specific sentence or paragraph. Those specific comments were not repeated by other respondents and are listed separately following our reply to the general issues. This list of specific comments does not include editorial comments concerning word spellings, sentence syntax, etc. If the accuracy of a statement was questioned, the statement was verified and corrected. Comments which requested that information be added to the document without providing documented sources of that information were not addressed here.

After public comments had been gathered on the health assessment the U.S. Army, Shell Oil Company, the state of Colorado, the U.S. Environmental Protection Agency, and the U.S. Fish and Wildlife Service reached, on June 13, 1995, an agreement for a conceptual remedy for the cleanup of RMA (the Conceptual Agreement; Colorado, 1995). The Conceptual Agreement incorporates 28 specific components of the conceptual remedy that were incorporated in the sitewide alternatives for water, structures, and soil as presented in the final Detailed Analysis of Alternatives report and carried forward as integral components in the Proposed Plan released in October 1996 (RMA, 1995). Some of the conceptual remedy components are integral components of both the on-post and off-post remedial programs that were considered in the selection of the preferred alternatives. The final Record of Decision (ROD) for the Offpost Operable unit was signed December 19, 1995 (HLA, 1995). That ROD incorporated the relevant Offpost portions of the Conceptual Agreement. The ROD documenting the final decision on the final cleanup of the Onpost Operable Unit of the Rocky Mountain Arsenal was signed June 11, 1996. The Onpost ROD incorporates both the Conceptual Agreement components relevant to the final cleanup on the Onpost Operable Unit and those additional components protective of human health and the environment.

The 28 specific components outlined in the Conceptual Agreement which form the conceptual basis for the final cleanup decisions include provisions for Onpost cleanup of surface and subsurface soils in specific locations, for UXO clearance, and for demolition and disposal of all contaminated structures. The Conceptual Agreement provides for the ongoing operation of all existing groundwater pump and treatment systems including the Irondale, Northwest Boundary, and North Boundary containment systems as well as the system installed north of the RMA boundary in the Offpost area. Further, the Conceptual Agreement provides that the U.S. Army and Shell Oil Company will, working with the South Adams County Water and Sanitation District (SACWSD), provide 4,000 acre feet of water, a system of water distribution lines, and individual residence hook-ups for all existing well owners within the Offpost area delineated by the plume of DIMP-contaminated groundwater. The extent of that plume will be determined as that area where the last quarterly groundwater monitoring results detect DIMP at levels greater than 0.392 ppb (the current detection limit for DIMP). The Conceptual Agreement specifies that, if DIMP is subsequently detected at levels greater than 8 ppb in additional existing or newly drilled wells, the Army and Shell will pay for hook-up to the water distribution system or provide a deep well or other permanent solution.

The June 13 Conceptual Agreement and the subsequent RODs resolve many of the controversial issues regarding the remediation of contamination at RMA. Likewise the agreement also answers, directly or indirectly, many of the questions or issues raised during the public comment period on this health assessment. In the replies given below on specific issues or questions we have given ATSDR's answer to that issue or question and, when relevant, we have indicated what effect the June 13, 1995 Agreement and the RODs have on that issue or question.

ISSUE #1: State of Colorado standards v. Federal standards

Comments on diisopropyl methylphosphonate (DIMP)

The state of Colorado and one individual questioned why ATSDR utilized EPA's 600 ppb Lifetime Health Advisory (LTHA) level for human exposure to diisopropyl methylphosphonate (DIMP) rather that the 8 ppb value adopted by the state.


In the January 17, 1995 public comment release of the Rocky Mountain Arsenal public health assessment (see p. 95-96), ATSDR explained its rationale for relying upon the EPA LTHA. That section of the assessment recognizes the differing scientific opinions on the potential toxicity of DIMP and explains that, based upon the available toxicologic research, ATSDR concludes that "....the Lifetime Health Advisory and RfD, established by EPA, appears to be protective of public health". Please see Appendix E for a summary of ATSDR's evaluation of DIMP.

The state, in their comments, further points out that the 8 ppb value adopted by the Colorado Water Quality Control Commission is a .."legally enforceable, health-based standard and should be used (by ATSDR) as the comparison value in all tables and discussions". However, no actions taken by ATSDR in the process of conducting an independent analysis and developing a public health assessment precludes the state from enforcing its rules. The goal of ATSDR in matters such as these is to seek to minimize or eliminate human exposure to environmental contaminants at levels that may cause harm. In our opinion, unless and until further study indicates that the EPA LTHA of 600 ppb is not protective of human health, public health is not further protected by limiting exposures to a lesser value of DIMP. The state of Colorado is, of course, free to adopt and implement a standard more strict that federal standards or guidelines if it so chooses.

While the state or other reviewers did not offer or identify additional (new) data or information that would indicate that the EPA LTHA for DIMP is not protective of public health, efforts are ongoing to further resolve this issue. The Army has recently funded and initiated a two-generation reproductive study in mink fed DIMP. The study's objective is to determine the toxic effects, if any, of DIMP on female mink that undergo mating, gestation, parturition, and lactation while ingesting DIMP in their feed. The study is designed to eliminate the short-comings of the previous toxicologic studies and to be responsive to the concerns raised by the Colorado Department of Public Health and Environment and the Colorado Water Quality Control Commission. A final report on this study will not be available until December 31, 1996.

Because DIMP is a very uncommon and controversial groundwater contaminant, ATSDR is also conducting an independent review and analysis of the previous toxicologic studies of DIMP. The public comment draft of that toxicological profile is scheduled for release in the Fall of 1996.

If either of those studies lead to the conclusion that the EPA LTHA for DIMP is not protective of public health, ATSDR will, as necessary, reevaluate the public consumptive use of Offpost Study Area groundwater at that time. However, the June 13, Agreement (Colorado, 1995) and both the Offpost and Onpost RODs (HLA, 1995; Foster Wheeler, 1996) provide initially that a municipal water supply system, deeper wells, or other permanent solutions will be provided to Offpost area well owners with greater than 0.392 ppb DIMP and then, at subsequent dates, to provide replacement water for those well owners found to have greater than 8 ppb DIMP in their wells. Thus, the remedial actions to be taken in the Offpost area should largely, if not totally, eliminate human ingestion of groundwater containing 8 ppb DIMP or greater. The need for a follow-up reevaluation of the public consumptive use of DIMP-contaminated groundwater is, therefore, not likely.

During ATSDR's evaluation of contaminants in the Offpost Study Area groundwater, an inventory was compiled of the levels of DIMP contamination in private, drinking water wells. That data was included in an October 14, 1994 draft of this public health assessment which was reviewed by the state, Tri-County Health Department, EPA, Army, USFWS, and Shell Oil Company. The October 1994 draft listed about 16 domestic, drinking water wells in use that produced water containing more than 8 ppb DIMP(19) but less than 600 ppb DIMP. Of those wells, about seven were apparently not supplied with bottled water by the state at that time.

Those 16 drinking water wells with DIMP content less than 600 ppb were not listed in Tables 14 and 15 of the January 17, 1995 public comment draft of the assessment because several of the reviewers and ATSDR concluded that inclusion of data was confusing to the readers when ATSDR's conclusion was that no adverse health effects could be attributed to ingestion of DIMP from those wells.

In a related matter, the state in their comments expressed concern that ATSDR has relied upon the state's bottled water program and "has failed to evaluate what risks would exist if the bottled water program was terminated..". This is incorrect. As stated on pages 155-156 of the January 19, 1995 assessment, the Offpost Study Area wells... "were evaluated for health effects that could result from chronic ingestion of the well water, even though chronic ingestion of the levels of contaminants detected in those wells is not likely occurring, because bottled water is supplied to those residences".

If ongoing research were to indicate that chronic ingestion of DIMP at concentration less than 600 ppb(20) may result in harm, the health of people living in the Offpost Study Area residences not supplied with bottled water (about 21 people as of October 1994) and continuing to use those drinking water wells for long periods of time may be at risk. Notwithstanding ATSDR's evaluation of DIMP, the Offpost ROD documents the Army and Shell Oil Company agreement to supply bottled water to users of domestic wells with contaminants exceeding levels set by remediation goals or other Applicable or Relevant and Appropriate Requirements (ARAS; HLA, 1995, p. DS3).

Comments on Chlorophenylmethyl sulfoxide (CPMSO), Isopropylmethyl phosphonate (IMPA), and Chloroform (CHCL3)


The state has commented twice that ATSDR should specify that the 20 ppb Longer-Term Health Advisory (L-THA; for children) comparison value used to evaluate Chlorophenylmethyl sulfoxide (CPMSO; see Tables 5A and 8) is a drinking water standard developed by EPA Region 8 (Denver) and is not a national EPA standard. The state further commented that it has proposed a lower standard of 5 ppb.


ATSDR has footnoted Table 5A for Offpost Study Area Groundwater and Table 8 for Surface Water to indicate that the cited comparison value was developed by EPA Region 8 for use with that EPA Region. With regard to the state's proposal of 5 ppb as a health advisory level for this compound, the historical detections of CPMSO in Offpost groundwater have not exceeded 17 ppb (average 8.58 ppb) and has been detected in only 8 of 474 samples (1.7%) collected between 1985 and 1990. CPMSO, CPMS, and CPMSO2 (see Table 5A) have not been detected in Offpost Study Area drinking water wells since 1990. ATSDR's assessment of the potential human health effects of groundwater ingestion exposure to CPMS, CPMSO, and CPMSO2 would not differ if we had relied upon the state's proposed, but not yet adopted, 5 ppb comparison value. Further, ATSDR has not identified a potential Offpost surface water pathway of human exposure to these compounds.

In the Offpost ROD (HLA, 1995) the Army and Shell Oil Company agreed to a remediation goal for the Offpost groundwater of 30 ppb CPMS and 36 ppb CPMSO and CPMSO2.


The state also commented that they've proposed a 6 ppb Lifetime Health Advisory level of Isopropylmethyl phosphonate (IMPA). The state's proposed level is in contrast with the EPA LTHA of 700 ppb.


A query of the RMAED conducted on October 15, 1993 disclosed that IMPA has not been detected in any of the 116 analyses of Offpost drinking water wells conducted specifically for that compound. The detection limit for those tests was 50 ppb, an order of magnitude less than the 700 ppb level set by EPA as the LTHA for this compound.

Some of the toxiokinetic and toxicologic data that can be used in the evaluation of IMPA comes from studies of isopropyl methylphosphonofluoridate (GB or Sarin) and DIMP. Since these compounds metabolize to form IMPA in living systems, these data are applicable to IMPA. Studies suggest that IMPA is rapidly eliminated from the body in the urine (EPA, 1992).

Because of the similarity between DIMP and IMPA and the fact that IMPA has not been detected in Offpost drinking water wells at levels 10-fold below the EPA LTHA value, ATSDR does not consider IMPA a contaminant of concern in the Offpost groundwater. In the absence of a completed or potential pathway of human exposure to IMPA, the compound was not and could not be further evaluated, but the widespread occurrence of DIMP in the Offpost area was carefully evaluated.


The state of Colorado asserts that ATSDR ignored the promulgated State health-based standard for chloroform (CHCL3).


ATSDR relied upon two comparison values for the evaluation of CHCL3; the Maximum Contaminant Limit (MCL), a federal drinking water standard and the Cancer Risk Evaluation Guide (CREG). At this time there is no specific MCL for CHCL3 but, the compound is regulated under the total trihalomethane MCL of 100 ppb. On the other hand, the CREG for CHCL3 has been set at a very conservative level of 6 ppb. ATSDR reviewed the standards set by the state for chloroform and discovered that those standards do not establish a specific contaminant level for private wells. For community systems the state requires monitoring for CHCL3 but again no specific standard is established. In light of the available state and federal standards, ATSDR chose to utilize the MCL and CREG standards.

During the interval from 1985 to 1993 CHCL3 was detected in Offpost drinking water wells in 79 of 523 samples. The maximum detected value was 100 ppb and the 79 detections averaged 15.37 ppb. However, in the interval from October, 1990 to December, 1993 CHCL3 was found in 19 of 128 samples of those drinking water wells. During this later interval CHCL3 detections averaged 6.36 ppb. Because these detections were in excess of the CREG (6 ppb), CHCL3 was evaluated further and the specific wells known to be contaminated with more than 6 ppb CHCL3 were identified (see Table 13). Four wells were identified with CHCL3 levels ranging from 8.33 - 25 ppb. It was determined that no adverse health effects would result from the chronic ingestion of water from those wells (see p. 156 and Appendix B of the January 19, 1995 Public Health Assessment).

In the Offpost ROD (HLA, 1995), the Army and Shell Oil Company agreed to a remediation goal for the Offpost groundwater of 6 ppb CHCL3.

ISSUE #2 - Health Studies and Health Outcome Data

Comments on Health Studies

One member of the public asked if ATSDR may initiate studies of the health effects of contaminants released and potentially released at this site.


Based upon site investigations conducted at RMA during the 1980s, ATSDR provided funding to the Colorado Department of Public Health and Environment to conduct exposure studies in the nearby residential communities. The objectives of those studies were to gather data on biologic indicators of potential human exposure to RMA contaminants. ATSDR also provided grant money to Colorado State University to conduct health outcome studies in the same communities studied in the exposure studies. Those studies have sought to identify health outcomes that might be related to RMA contaminants. Those health outcome studies are ongoing.

Additional information on those investigations is given in the Health Outcome Data and Public health Implications sections of this assessment.

Comment on public health education

One member of the public asked if ATSDR would consider disclosing the known human health effects of each contaminant of concern included in this report, or mentioned in fact sheets relating to RMA, so that the public could determine the if ailments or particular health concerns could relate to possible exposures to RMA contaminants.


During the lengthy process of completing the remedial investigations of the Onpost and Offpost areas of RMA, risk or endangerment assessments have been conducted that examine the potential human health effects that could be associated with exposure to RMA contaminants. Those endangerment assessments (referenced in this assessment) are available in the numerous public libraries in the Denver area (such as the Commerce City and Montbello libraries) designated as repositories for remedial investigation/feasibility study documents prepared for RMA.

Data establishing actual exposure to environmental contaminants is essential to the evaluation of the human health consequences of that exposure. This public health assessment is a site-specific, comprehensive, independent evaluation of the potential human health effects that may be associated with actual or potential environmental exposure to RMA contaminants.

The data or information essential to a definitive evaluation of the public health implication of environmental exposure include those that fully describe the pathway of that exposure (see p. 106, January 17, 1995 Assessment). In order to develop a meaningful evaluation of the potential health consequences of an exposure to environmental contaminant(s), the concentration(s), duration(s), and route(s) (ie. dermal, ingestion, inhalation) of exposure to those contaminants must be known.

Human exposure to chemical compounds to a multitude of chemical compounds from diverse sources (eg. air pollution, occupational exposure, medicines, food additives) occurs on a daily basis. Moreover, the specific "ailments or particular health concerns" the respondent was seeking to evaluate can themselves, result from differing causal factors or mechanisms. The public health assessment prepared by ATSDR documents the systematic analysis to identify pathways of human exposure to environmental contaminants of known source, concentration, and duration and to identify and, if possible, isolate or eliminate confounding sources of human health effects. Appendices B & C of the RMA public health assessment contain additional information that may be useful to the respondent.

Comments on Multiple Chemical Exposures

One member of the public noted that ATSDR's evaluation of public health is based upon individual contaminant exposures and asked if a more relevant approach for RMA would be based upon multiple chemical exposures?


Human exposure to chemicals at many hazardous waste sites is often not limited to a single substance but to mixtures of various chemicals. However, the vast majority of substance-specific research focuses on individual chemicals. Accordingly, one approach that is sometimes used to estimate the toxicity of chemical mixtures is to assume that the chemicals a mixture composed of have an additive toxic effect. There is a considerable body of scientific information that documents that the specific components of a chemical mixture influence toxicity. Thus, the overall toxicity of a certain mixture might be higher or lower than simply adding the toxicity of each chemical component of the mixture.

Limited research has been conducted on the toxicity of chemical mixtures. Specifically, methods need to be developed to better understand the behavior of chemical mixtures in the environment and their actual impact on human health. ATSDR recognizes the public health significance of human exposure to chemical mixtures and has supported mixture oriented research through the National Institute of Environmental Health Sciences.

ISSUE #3: Wildlife and Other Potential Foodchain Issues.

The U. S. Fish and Wildlife Service provided specific comments and new data on contaminant levels in wildlife sampled at RMA (USFWS, 1995). ATSDR has considered this new data and has revised the text and Tables 12A and 12B to reflect this new data. Two individuals raised questions or offered comments that will be discussed here.

Comment on the deer population

One individual questioned the significance of the high population density of deer at RMA, and asked if that could be because of the health of the predator population is bad or if that could be because the area (RMA) is enclosed by fencing and free from human encroachment?


With the construction of the tall perimeter fence in 1990, the USFWS (1995) considers the RMA deer population a closed population. While many factors may contribute to the increase in herd size, the published USFWS reports identify the boundary fence and lack of hunting as important factors. Health of the predator population, due to any cause, has not been identified as contributing factor to the increasing deer herd size. In fact, USFWS observations indicate that the predator (coyote) population is keeping pace with the increases in the deer population at the Arsenal (Ronel Finley, USFWS, May 30, 1995, personal communication).

Comments on ecosystem health

Two members of the public commented on various aspects of this issue. Specifically, one member of the public commented that ATSDR had not given sufficient attention to RMA wildlife health or the risk to RMA wildlife from exposure to contaminants. The respondent further asserted that by examining edible species on RMA for human consumption, ATSDR had missed several major issues in relation to biota exposures to contaminants. Another respondent questioned whether the vast number of animal samples frozen and the necropsy reports completed would be included as a basis for pathway assumptions and perhaps otherwise undetected human health effects.


One of the principal objectives of a public health assessment is to determine if people could or have been exposed to environmental contaminants at levels that could cause harmful effects. An assessment of wildlife or ecosystem health is not an ATSDR objective. However, other studies conducted during the remedial investigation do assess ecologic risk (see the endangerment assessment reports referenced in this report).

During the ongoing studies conducted by or for the Rocky Mountain Arsenal National Wildlife Refuge, USFWS staff also compile species-specific data and information on the health of RMA wildlife. Those studies evaluate a diverse spectrum of wildlife and habitat attributes including, but not limited to, data on individual mortalities, delineation of areas of greater risk to wildlife, population trends and dynamics, monitoring of sentinel or management indicator species, prevalence of disease, and levels of contaminant uptake. ATSDR reviewed relevant data from those studies to identify, define, and quantify potential pathways of human foodchain contamination. That data and information was assimilated in this assessment.

One respondent suggested that because ATSDR did not examine wildlife health directly the evidence of widespread contamination was not fully appreciated or evaluated. The examples given were that the absence of starlings was a "red flag to scientists" and ground dwelling species such as badgers have excessively high levels of dieldrin in some cases. ATSDR has reviewed the findings of the wildlife health and management studies conducted at RMA (cf USFWS, 1995). Studies such as those to develop the biomonitoring plan for the European starling (USFWS, 1995, Appendix A.1.a.) or to evaluate dieldrin toxicity in badgers (USFWS, 1995, Appendix A.1.b.) are gathering data that will assist refuge managers in their efforts to successfully manage these species and their habitat components. Those studies also reveal that, in addition to the toxicity of the site, there may be many factors that affect the overall health of the species. ATSDR has not ignored the information generated by these ongoing studies, but to assess the potential human health affects of environmental contamination at RMA, ATSDR must focus on evidence of contaminants directly in the human foodchain.

Comment on adequacy of waterfowl data

One member of the public commented that the data given for Mallard duck on page 76 of the assessment was not adequate and that data on percentages of detects for each chemical, birth success rates, and percentages of time spent on RMA per year would be informative.


The focus of the ATSDR public health assessment is to assess the potential risk associated with human exposure to RMA contaminants. Thus, data utilized in the assessment is descriptive of the body-burden of contaminants found in the commonly edible wildlife species that inhabit RMA and is, directly and indirectly, a function of and integrates the types of variables identified by this respondent.

The issues raised by the respondent are important issues to the USFWS. The USFWS is engaged in an extensive biomonitoring program (BMP) for the RMA National Wildlife Refuge. The waterfowl investigations component of that BMP has the objectives of determining the degree of contamination, the reproductive success, and the age, sex, and species of waterfowl that may be the best indicators of contaminant impact on the Refuge. The overall objectives of the BMP are to ensure that clean-up is successful at protecting the wildlife species that inhabit the RMA refuge, and to ensure that the Refuge habitats are restored (USFWS, 1995).

Comments on the potential foodchain pathway for DIMP in vegetable produce grown in a portion of the Offpost Study Area.

The Army, Shell Oil Company, the state of Colorado, and one member of the public offered comments dealing with various aspects of ATSDR's evaluation of the potential vegetable foodchain pathway on the Offpost Study Area lands immediately north of RMA. The central issue is whether it is safe to eat the vegetable produce that is or could be grown on those lands north of RMA, near First Creek, and south of the Burlington Ditch and O'Brian Canal? Question raised by respondents on specific aspects or facets of this issue will be incorporated in our reply.


Based upon ATSDR's review of Offpost Study Area data on the distribution and concentration of surface soil and groundwater contaminants and information on past, present, and potential future land uses in that area ATSDR concluded that there was a "...low, but presently unquantified, potential for contaminant uptake in garden vegetables and crops grown in contaminated Offpost surface soils and watered with contaminated water..." (see p. 180 of the January 19, 1995 Public Health Assessment). In reaching that conclusion ATSDR reviewed the assumptions and methods used in endangerment assessment prepared for the Offpost Operable Unit (HLA, 1992b). That assessment of risk associated with the consumption of vegetables irrigated and grown utilized appropriate data and reasonable, conservative assumptions. The calculations given in the endangerment assessment support the conclusion that consumption of vegetables grown in this area would not result in any adverse health effects. However, site-specific data on the concentration of contaminants in vegetables grown in the area of greatest potential risk was not available at the time the endangerment assessment was completed. This data gap was a factor in ATSDR's decision to categorize consumption of these garden vegetables, potentially contaminated by DIMP and nitrate, as an Indeterminate Public Health Hazard.

Subsequent to the completion of the endangerment assessment data has been developed on DIMP contaminant levels in garden vegetables grown in the area of potential concern. The Army asked Tri-County Health Department to obtain samples of garden vegetables from Offpost sites to determine what concentrations of DIMP, if any, are in Offpost vegetables. The samples were collected from the garden of private residence north of RMA on October 12, 1995 and from two large vegetable farms on November 10, 1995. The private garden was selected by the Army because it is irrigated only with water from well 1178B which has higher concentrations of DIMP remaining than any other Offpost area well. The concentrations of DIMP in that well have ranged from about 150 to 950 ppb. The commercial farms were selected because they utilize a combination of groundwater (DIMP <20 ppb) and surface water (uncontaminated by DIMP).

The vegetables were analyzed using a recently developed method to determine DIMP concentrations in vegetables (detection limit, 20 ppb). The concentrations of DIMP detected in the private garden cucumbers ranged from 340 to 920 ppb and the tomatoes from that garden contained DIMP at an unquantifiable level below the detection limit. The vegetable samples (corn, onion, chile pepper) taken from the large vegetable farms contained no detectable DIMP.

Comparison of this 1995 garden vegetable data with the calculation of potential risk given in the Offpost Endangerment Assessment (HLA, 1992b) indicates that even under a "worst-case " exposure scenario, the consumption of vegetables irrigated with DIMP-contaminated groundwater is not expected to result in adverse health effects. This conclusion is based upon the estimation of the potential DIMP concentration in lettuce. Lettuce was selected to evaluate the potential risk associated with consumption of Offpost-grown vegetables because studies have shown that plant leaves have the highest potential to accumulate DIMP. Other "worst-case" assumption included in this evaluation were a 900 ppb concentration of DIMP in groundwater, a high ingestion rate 0.125 kg/day), and daily ingestion for 30 years. Based upon these conservative assumptions the calculated associated risk, expressed as a hazard quotient, is 0.2 (level of concern is 1.0).

Comment on the potential for contaminated vegetables to be grown on the property owned by Shell

Related to the issue of the potential risk associated with the consumption of Offpost-grown vegetables is the issue raised by the state that because Shell Oil Company has not agreed to deed restrictions or rezoning there is a potential for vegetables to be grown on Shell's lands immediately north of RMA.


The basis of this concern is that the historical concentrations of contaminants in surface soils and groundwater, have been the highest in this area. This issue appears to have been resolved by Shell in a September 10, 1991 letter to the Army (Shell, 1991), with copies to the state, EPA, USFWS, and ATSDR. In that letter Shell detailed the land use options available for those lands and stated that "...(f)or all these reasons, Shell does not foresee any circumstance underwhich it would consider residential use for any of the Shell Lands".

In addition to the information given above, important institutional controls have been agreed to in Components 17 and 23 of the Agreement of June 13 (Colorado, 1995) and in the Offpost ROD (HLA, 1995). Those components further ensure that no adverse public health effects might result from the ingestion of vegetable produce grown in the Offpost Study Area. Component 17 provides, among other things, that domestic well users within the area delimited by the areal extent of DIMP at the detection limit of 0.392 ppb in groundwater will be provided with a municipal water supply system. Component 23 further provides, among other things, that institutional controls will be utilized to prevent domestic use of contaminated Offpost water and that Shell Oil Company commits to execute and record proper documentation to preclude drilling of water wells on the property owned by Shell north of RMA.

Based upon the new data and information given above, ATSDR has revised its previous conclusion regarding a potential foodchain pathway in the Offpost Study area. We now conclude that the consumption of vegetables irrigated with DIMP-contaminated groundwater is not expected to result in adverse health effects and, therefore, that there is no potential Offpost foodchain pathway. The text of this public health assessment has be revised accordingly.

ISSUE # 4: Onpost Contamination

Two individuals raised questions on Onpost contamination. Some of those Onpost contamination concerns related to wildlife exposure to contaminants. Those issues were addressed under Issue 3 above. The remaining issue deals with the human health risk posed by nerve agent and unexploded ordinance at RMA.

Comment on nerve agent and unexploded ordinance

One individual questioned why nerve agent and unexploded ordinance were not given more consideration in the public health assessment? The individual commented that there have been accidental releases of these toxins and suspected exposure of workers during interim cleanup and that these events are not admitted or considered with past or present exposures.


Inventory and site-specific investigations to identify, locate, and remove, destroy or neutralize nerve agent and unexploded ordinance have been an integral component of the remedial investigations conducted Onpost and of the many specific investigations leading up to the decisions to implement the Interim Response Actions (IRAs). Health and safety plans are developed and implemented in conjunction with all Onpost investigations and remedial actions.

The health and safety of the Onpost workers, public visiting the site, and the residents of nearby communities is of paramount importance to the U.S. Environmental Protection Agency, the U.S. Army, the U.S. Fish and Wildlife Service, the Colorado Department of Public Health and Environment, the local health departments, the contractors conducting the Onpost work, and ATSDR. As a result of Onpost investigations, IRAs have been conducted to eliminate or minimize the risk associated with the presence of nerve agent and UXO.

In addition to site-specific or activity-specific health and safety plans the Program Manager for Rocky Mountain Arsenal has established a Contingency Plan (see RMA, 1993a for an overview) designed to minimize hazards to human health and the environment from fires, explosions, or any unplanned release of hazardous substances to air, soil, surface water, or groundwater. The Contingency Plan is a detailed, four-volume document which assigns responsibility for emergency response procedures, prescribes official notification and record-keeping procedures, and ensures, as appropriate, notification of officials and agencies including the Governor, local Mayors, emergency responders, police, hospitals, the EPA, and the Occupational Safety and Health Administration. This Contingency Plan has been developed in full compliance with federal requirements for such plans.

To further ensure that the many ongoing activities and uses of the Arsenal and National Wildlife Area do not result in inadvertent exposure or accident, the USFWS manages an activity coordination program. That program, in conjunction with provisions of the Contingency Plan provisions, seeks, among other objectives, to minimize conflicts in schedule or type of activity and to supply maps and other essential information to those parties with a need to know in a timely fashion (see USFWS, 1993).

Component 14 of the Conceptual Agreement of June 13 (Colorado, 1995) specifically provides for the systematic geophysical detection and subsequent destruction and/or disposal, as appropriate. These safeguards are incorporated in the Onpost ROD (Foster Wheeler, 1996). Thus, upon completion of the final Onpost cleanup activities, UXO and munitions wastes are expected to represent a minimal human health risk.

The provisions listed above describe a health and safety program designed to protect the health of Onpost workers and Offpost residents. ATSDR has reviewed the important elements of this overall health and safety program and does not find it deficient. While minor accidents and incidents have happened and will happen, there is no reason to believe that the procedures, planning, mitigation measures, and ability is not in-place to assure the continued protection of public health.

ISSUE # 5: Offpost Contamination

Comments on Offpost Study Area Contamination

The state and one member of the public expressed concerns about potential human exposure to surface soil and groundwater contaminations found on and beneath the Shell Oil Company properties located immediately north of RMA. Both respondents expressed concern that safeguards did not exist to prevent a potential future pathway of human exposure to surface soil contaminants found on those lands, lying within zones 3 and 4 of the proposed plan for the RMA Offpost Study Area (RMA, 1993).


As stated in our reply to concerns about a potential foodchain pathway for vegetables grown on the Shell Properties (see p. 249 above), Shell Oil Company stated in writing that they do not foresee any circumstances underwhich it would consider residential use for any of the Shell Lands (Shell, 1991). ATSDR reviewed the data and information compiled by the remedial investigations (ESE, 1988; HLA, 1992a) and the endangerment assessment (HLA, 1992b) and concluded that groundwater contaminants, not surface soils, represent the greatest potential risk to human health. This was also the conclusion of the Offpost endangerment assessment and was the reason groundwater remediation alternatives were developed for the Offpost zones identified in the 1993 proposed plan for cleanup of the Offpost Study Area.

The Agreement of June 13 (Component 22) does provide for revegetation of approximately 160 acres of dieldrin-contaminated surface soils in the Shell Lands. Shell Oil Company has also agreed (Component 23) to impose restrictions (e.g. covenant/negative easement) on its properties precluding the drilling of all groundwater wells into the alluvial aquifer under Shell's property for future use until such groundwater no longer contains contaminants in exceedance of cleanup standards. These provisions are incorporated in the Offpost ROD (HLA, 1995).

Based upon ATSDR's review of surface soil contaminant levels on the Shell properties and the provisions made part of the Offpost ROD (HLA, 1995), ATSDR concludes that a future pathway of human exposure to the surface soil or groundwater of the Shell properties will not be created.

Comments on Offpost Contamination in Montbello and Other Areas South of RMA

Two members of the public and the City and County of Denver commented on potential contamination south of RMA. The concern expressed is that the residents of those areas could have been exposed in the past to windblown contaminants from RMA. The respondents suggested that: 1) because individual human health was not examined, ATSDR cannot conclude that community members were not affected by RMA contaminants; 2) a "base line health study" is needed to compare blood and urine samples collected from current and past residents of communities such as Montbello, Concord, Deer Trail, Valley Station, and Green Valley Ranch with a control group from Watkins or Bennett; and 3) a comprehensive surface and subsurface soil sampling is necessary.


Because, in the last 20 or more years, numerous actions have been taken at RMA to minimize or eliminate potential or completed pathways of human exposure to contaminants, and because numerous health studies have been and still are being conducted to evaluate the potential health effects, if any, from exposure to RMA contaminants, ATSDR focused the public health assessment for RMA on the possible present and future pathways of exposure and the potential health effects that may arise. This is not to say that ATSDR did not examine data descriptive of past events and indicative of previous conditions, for indeed, present conditions are the result of past events.

ATSDR conducted a thorough review of the data compiled on the contamination of surface soils both Onpost and in the Offpost Study Area to the north of RMA. Data on possible surface soil contamination was not developed or areas south of RMA during the remedial investigation. While data on subsurface soil contamination was also reviewed, that data was not used in the assessment because people are not typically exposed to subsurface soils.

The large number of surface soil samples collected from the Onpost area did permit ATSDR to perform a systematic examination of the pattern of distribution of windblown and deposited contaminants. That analysis is disclosed in the Potential Onpost Surface Soil and Sediment Pathway section of the assessment. As noted in the text, the gradational distribution pattern of the contaminants is consistent with windblown transport of contaminants from the central six sections of land including the North and South Plants and Basins A and F.

Windblown contaminants are detected in the surface soils to the south east and south of this central core or source area of contaminants and are noted in the assessment (see Table 16). Those surface soils are the historical record of previous events and conditions. Thus, by examining those surface soils we are examining a record of contamination migration in the past. The concentration and distribution of those contaminants is a record of possible past pathways of exposure. However, the measured concentration of those windblown contaminants are below levels of health concern before reaching the east or south boundary fences of RMA. Thus, there is no evidence that, in the past, residents of Montbello or other communities located further to the south of RMA were exposed to RMA contaminants at levels of human health concern.  

In 1995 the EPA began a program of surface soil sampling in the Montbello area and the adjacent commercial/light industrial areas to the west and south. That investigation, completed in February 1996 (CDM, 1996), did not find contaminants at levels of health risk for residential exposure. Volatiles, semivolatiles, pesticides, PCB, and metals were found at levels consistent with levels expected in neighborhoods in a metropolitan area. The data collected does not show a relationship to activities at RMA.

People are, on a daily basis, exposed to a variety of chemical compounds. Those exposures can occur at home, at play, or at work. Factors such as occupation, lifestyle, or heredity can and do play an important role in the general health and well-being of an individual. Without specific evidence of human exposure to environmental contaminants, it is generally not possible to conduct meaningful health studies to evaluate the potential effect(s) of exposure to those environmental contaminants. Unless evidence (dose and duration) of environmental exposure can be established, the direct medical testing of individuals blood or urine may yield results that describe the relative health of the individual but are not likely to disclose conclusive information regarding any possible environmental exposure(s) from any source(s).

The Agreement of June 13 (Colorado, 1995) does provide, in Component 18, for the development of a medical program as an integral component of the final cleanup plans for RMA. Component 18 specifies that a medical monitoring plan be developed with the goal of monitoring any potential off-post impact on human health due to the remediation and provide mechanisms for evaluation of health status on an individual and community basis until such time as the Onpost soil cleanup is completed. This provision was incorporated in the Onpost ROD (Foster Wheeler, 1996) and in December 1995 the CDPHE convened the first meeting of the Medical Monitoring Advisory Group to assist in the preparation of a plan to ensure the protection of public health during the final cleanup of RMA. Thus, the community members surrounding RMA can be assured that throughout the final cleanup process at RMA provisions will have been made to ensure the protection of public health.

ISSUE # 6: Past Exposures and the ATSDR Hazard Ranking Scheme

Comments on Past Exposures

The City and County of Denver and one member of the public commented that past exposure to more than 40 years of air emissions from RMA were not characterized or factored into ATSDR's evaluation and that such long-term past exposures are extremely relevant to chronic toxicity. Further, because past pathways were not fully evaluated, how can ATSDR conclude that "exposure to RMA contaminants at levels of public health concern has not occurred to Montbello residents" (see draft assessment, p.169)?


As stated in the public health assessment and previously stated above in our reply to Issue # 5, the focus of this assessment is on the identification of completed and potential present and future pathways of human exposure to contaminants released from RMA. Because the present is the key to the past our study of contamination in environmental media did examine the historical record of contamination at and surrounding RMA. Unlike media such as groundwater or soil, the "record" of contamination in the air media is short-term, much more rapidly diffused or diluted and not "preserved" unless recorded by air sampling. However, a partial record of atmospheric contamination can be reconstructed in some cases by examining the surface deposition of windblown contaminants.

In an effort to ascertain if wind-borne contaminants had migrated to offpost locations to the east or south of RMA, we examined the distribution and concentration of surface soil deposits contaminated by wind-borne RMA contaminants. Those surface soil deposits do not provide a record that a past pathway of human exposure to wind-borne contaminants at levels that may result in adverse health effects was created to locations to the east and in the Montbello community to the south of RMA. Air monitoring data is not available, however, to detail the possible past transportation of volatile and semi-volatile atmospheric components (VOCs and SVOCs) from RMA to the Montbello community and others to the south of RMA.

To the north and west, the data gathered in the remedial investigations of the Offpost Study Area to the north of RMA (ESE, 1988; HLA, 1992a), ongoing air monitoring investigations, and the several site-specific studies of human health discussed in the Health Outcome Data Evaluation section of this assessment were all considered in the development of this assessment. The health studies conducted to date have not attributed statistically significant health effects to the groups of people residing to the north or west who were assumed to be exposed to higher levels of contamination for longer durations in more environmental media than can be inferred for other areas surrounding RMA. Thus, while specific data recording air emissions for more that 40 years at RMA were not specifically considered because data do not exist, data collected from other environmental media do directly and indirectly record aspects of those past emissions and that data was considered. The review of the available data and information compiled does not suggest that the remedial and other investigations conducted by the Army, Shell Oil Company, EPA, ATSDR and others have detected important past pathways of human exposure. It follows that those health studies discussed in the Health Outcome Data Evaluation section have been focused on the communities most likely to display chronic health effects, if any, that may be associated with environmental exposure(s) to RMA contaminants.

Comments on the ATSDR Hazard Ranking System

The City and County of Denver questioned whether the ATSDR's public health conclusion categories selected were correct in light of past and present conditions at RMA. The respondents specifically questioned why:

    1) In light of the fact that several chemicals were detected Onpost for which regulatory or other appropriate comparison values do not exist and that chemical warfare agents and UXO will continue to represent a hazard at RMA, why does ATSDR consider the RMA Onpost area to be "No Apparent Health Hazard"?


The Public Health Conclusion Categories used by ATSDR are categories or classes within a simple classification system used to explain to the public the relative health hazard associated with the site. Numerous criteria and site-specific factors are considered when assigning a site or a portion of a site to particular conclusion category (see Appendix A). The health assessor must consider the information compiled in the assessment on the duration and intensity of the past, present, or possible future human exposure to the contaminated media of the site. ATSDR assigned the "No Apparent Health Hazard" to the RMA Onpost area because:

    1) Institutional controls over access and other uses of the RMA Onpost area have been, are, and will continue to be in-place until Onpost cleanup is completed. Those controls, including IRAs, have minimized or eliminated human exposure at levels of health concern to Onpost contaminants.
    2) There are no specific health outcomes that can be attributed to Onpost workers, even those workers with occupational exposures to RMA chemical compounds and contaminants.
    3) Even though Army nerve agent and UXO continue to represent physical hazards at RMA, the system of institutional controls regulating access and use, coupled with remediation completed under IRA and planned under the provisions of Components such as No. 1, 4, 10, and 14 (Colorado, 1995) and the Onpost ROD (Foster Wheeler, 1996), minimize the potential threat posed by those devices.

In summary, while in some Onpost areas of RMA there are environmental contaminants in concentrations that may result in adverse human health effects or UXO that may be a potential physical hazard, institutional controls regulating access and use coupled with past, present and planned future remediation projects have minimized or, in some cases, totally eliminated the potential for short- or long-term exposure to those compounds and substances at levels that may result in adverse impacts on human health.

    2) Because the public health assessment acknowledges that, in many cases, contaminant and environmental data are insufficient to permit a meaningful, retrospective evaluation of possible past pathways of human exposure, should not RMA be assigned to an "Indeterminate Public Health Hazard" category?


The public health conclusion category classification of RMA Onpost and offpost areas was completed for present and potential future pathways and human exposures. The RMA is a large, complicated facility with a long history of military and industrial activities. The offpost areas potentially affected by the migration of RMA-source contaminants are also large and complex.

RMA was established in 1942 and began routine collection of environmental contamination data in 1974. However, environmental data was not systematically collected during the interval from 1942 to 1974. Thus, for the early history of RMA there is insufficient environmental data to fully evaluate potential pathways of human exposure. This scenario is true for most large CERCLA sites.

The public health actions that follow an assignment to an "Indeterminate" category typically include data gathering to eliminate the data gap(s), remediation or removal actions to eliminate or minimize human exposure to significant levels of hazardous substances, and health actions such as health education, or health investigations. At RMA it is unlikely that data of sufficient precision can be gathered, reconstructed, modeled, or estimated to eliminates these past data gaps. Remedial actions have and are occurring that serve to minimize or eliminate human exposure to contaminants. Also, health studies are underway in the nearby communities. For these reasons, it serves no useful purpose to describe and classify RMA as an "indeterminate" site in the past or present. Because of the reasons summarized above, it is most accurate and communicates more clearly with the public to describe and classify the RMA Onpost area as a "No Apparent Public Health Hazard".

ISSUE # 7: Bias in Acceptance of Reports

The state and three members of the public commented that ATSDR has appeared to accept the analysis and conclusions drawn in the reports submitted in the technical reports supplied by the Army without question. The state further commented that the assessment ignores concern raised by the state, EPA, and the stakeholders regarding conclusions drawn in the Army reports. A member of the public asserts that the Assessment was prepared by "junior" personnel not qualified to conduct the study.


Several points of clarification are necessary to fully respond to these comments. First, it is important to recognize that approximately 1.5 million pages of documentation have been compiled from the investigations of environmental contamination at RMA. Most of that data and information have been compiled in reports prepared for EPA by the U. S. Army and Shell Oil Company. Those reports have been submitted for the review, approval, and use of EPA under the provisions of CERCLA. To ensure an orderly implementation of CERCLA requirements, a Federal Facilities Agreement (FFA), effective February 17, 1989, was signed by the Army, EPA, USFWS, ATSDR, Shell Oil Company, and the U. S. Department of Justice. Among the many provisions of that FFA there are provisions to establish requirements for the performance of the remedial investigations and the feasibility studies, to implement Interim Response Actions and expedite the final cleanup process consistent with protection of human health and the environment, and to provide for an orderly dispute resolution process. That dispute resolution process, utilized by the parties to the agreement, has ensured that concerns regarding the scope, content, and conclusions of the numerous studies and reports have been thoroughly examined and resolved. Thus, the FFA dispute resolution process has helped to ensure the scientific credibility of the investigations and reports compiled for RMA.

To prepare public health assessments or consultations ATSDR must ordinarily rely upon the environmental contamination data gathered by others. In so doing, ATSDR reviews the relevant raw data as well as summary reports compiled by others to determine if that data and information is accurate and of adequate scope to base our analysis. ATSDR has found the data and information compiled on the environmental contamination in and around RMA is comprehensive, thorough, and accurate.

The public health assessments prepared by ATSDR, including this assessment, are prepared by trained health assessors with relevant and appropriate scientific and technical backgrounds. As needed during the analysis or documentation phases, technical assistance on specific issues is provided to the health assessors by other ATSDR specialists or specialists in other agencies, groups, or academic institutions. The assessment or consultation prepared is based upon an independent review and analysis of the data compiled on environmental contaminants, pathways of human exposure, and relevant health data. Upon completion of the initial draft, if not sooner, the document is thoroughly reviewed by supervisory and management personnel. This initial draft is then circulated for comment to the Potentially Responsible Parties (PRP) and the federal, state, and local government entities that have been actively involved in CERCLA process at the site. The comments received from this initial review are reviewed by ATSDR and, if appropriate, corrections or additions are made to the document to prepare the public comment draft.

Before release of the public comment draft of the assessment, a review of the document is conducted by members of the Health Activities Recommendation Panel (HARP). The HARP review ensures that the ATSDR Divisions of Health Education, Health Studies, and Toxicology have the opportunity to review the assessment and comment on the findings and appropriate follow-up action(s). ATSDR public health assessments or consultations are not released for public comment without multiple internal reviews by staff and management for conformance to relevant scientific principles and agency policy and standards.

Thus, based upon the foregoing, ATSDR conducted and prepared an objective, third-party public health assessment based upon the available data and information compiled concerning environmental contamination and potential health affects associated with Rocky Mountain Arsenal. The health assessment conforms to agency policy and standards. Public health concerns were gathered by ATSDR through a series of public availability meeting conducted in 1993. An initial draft (Red Cover Draft, August 25, 1994) of the assessment was review by the Colorado Department of Public Health and Environment, the Tri-County health Department, EPA, USFWS, Shell Oil Company, and the Army. ATSDR reviewed the comments received on the Red Cover Draft and, as appropriate, modified the document. No comments offered by the state, the EPA, or any other entity reviewing the Red Cover Draft were ignored. However, on matters where factual dispute may exist (such as a safe level of DIMP in drinking water), ATSDR examined the available facts or studies and exercised its independent judgement in resolving the issue. The resulting revised draft was released as the public comment draft (Brown Cover Draft) on January 17, 1995.

In a similar fashion, in the preparation of this "Blue Cover" release of the public health assessment we considered the public comments received as well as any new data that might affect our evaluation. Public comments based in fact resulted in corresponding changes to the document. Perceptions not supported by fact have not resulted in changes to the assessment. New information developed on issues such as the potential Offpost foodchain and the presence of nitrates in Onpost groundwater was considered and that new data resulted in changes to our final conclusions and recommendations. It is hope that a review of ATSDR's response to public input and new data and information will, in itself, further demonstrate the lack of bias or favoritism in the conduct of this analysis or in the preparation of this assessment.


  1. A member of the public asked if the study of mortality among workers at the pesticide manufacturing plant at RMA, cited in the January 17 release of the RMA public health assessment, had been published in the peer reviewed literature and if the methods, study design, or conclusions had been critically reviewed?


Yes, the cited study (Amoateng-Adjepong, et al., 1995) has been published in the Journal of Occupational and Environmental Medicine, a peer reviewed journal. This study received critical review by ATSDR but we recognize, based upon some of the details of the questions asked by this respondent, that the discussion of the findings of this research incorporated in the January 19 release of this assessment were somewhat misleading. The etiologic factors are listed in the Amoateng-Adjepong report (1995) because they have been found to be associated with increased risk of biliary cancer in previous studies. The report does not state that those factors are causes at RMA, it just states that they have been suggested as etiologic factors in the past. The Health Outcomes Data Evaluation section of this edition of the public health assessment has been revised to clarify this point.

  1. The state of Colorado noted that nitrosamines have been detected beyond the NBCS in the last year. Detection of these compounds beyond the containment system is in conflict with the information given on page 227 of the assessment.


ATSDR has reviewed the May 1995 sampling data on the low-concentration occurrences of N-Nitrosodimethylamine (NDMA) in groundwater and has revised that portion of the public health assessment to incorporate this new information. In light of this new data, the Agreement of June 13, 1995 (Colorado, 1995) incorporates provisions (Component 25) for further monitoring and assessment of the occurrence of NDMA in the Offpost. The Offpost and Onpost RODs (HLA, 1995; Foster Wheeler, 1996) document the agreement to use 7.0 ppt as a preliminary remediation goal. The Offpost occurrence of NDMA (maximum 54.7 ppt) appears to be a very small area, just north of the North Boundary Containment System (NBCS), and localized in the First Creek pathway (HLA, 1996). The data gathered indicates that the NDMA is upgradient to the Offpost Groundwater Intercept and Treatment System and the O'Brian Canal; an area well within the "DIMP footprint area" of drinking water wells to be connected to a replacement water supply.

The concentration and distribution of NDMA is greatly reduced (<15.7 ppt) immediately downgradient to the NBCS even though the treatment system presently in use at that facility is not designed to remove NDMA. Preliminary evidence points to the possibility of biodegradation/mineralization of NDMA in the effluent of the NBCS as mechanism(s) which naturally reduce the groundwater levels of that compound (HLA, 1996; Pennington and others, 1996).

There is no present human exposure to the NDMA in groundwater and no future exposure is likely. The available evidence suggests that the human health significance of the Offpost detection of this compound is minimal.

  1. The City and County of Denver commented frequently that RMA is located on the northern boundary of the City and County of Denver and lies approximately 6 miles northeast of downtown Denver, not 9 miles as reported by ATSDR (emphasis added).


Because the proximity of contaminated sites to a person's residence is of frequent concern, ATSDR thought it was important to reply to this comment. The City and County of Denver is of course correct that RMA is located on its north boundary and the distance from downtown Denver (air miles from the corner of Larimer and 16th Street) to the southwestern corner is about 6.25 miles and to Building 111 in the center of RMA the distance is 10.5 miles. The remedial investigation documents prepared over the past several years and cited repeatedly have reported that distance as 9 miles. Because of the large size of RMA and range of distances that could be reported, ATSDR chooses to report the most commonly quoted distance.

  1. The City and County of Denver questioned if the "best efforts" mentioned in the Note of Explanation in the Assessment refers to compliance with ATSDR's statutory criteria or the protocol as described in the Forward to the Assessment?


The Forward describes the Agencies "best effort" to fulfill the statutory criteria set out in CERCLA, Sec. 104 (i)(6). No change is needed in the document.

  1. The City and County of Denver identified several sections of the public health assessment Summary that were in need of clarification.


The Summary has been updated and rewritten to clarify the items identified by the City and County of Denver and to reflect other changes in this document resulting from new data and information.

  1. In addition to numerous comments recording details of Onpost groundwater flow and changes in Offpost land use because of the opening of the new Denver International Airport, the City and County of Denver questioned why the section of the Assessment on Projected Future Land Use - Offpost only discusses the Offpost Study Area?


Several wording changes were made to clarify portions of the groundwater and land use sections. The section on Projected Future Land Use in the Offpost Study Area remains unchanged. That area was discussed in the Assessment because it was that geographic area which, if no remediation actions were taken, is potentially most affected by offpost groundwater contamination.

  1. The City and County of Denver questioned the summaries of "Possible Pathways Remaining" recorded in Table 5 of the Assessment. Specifically, Denver questions:
    Groundwater (Onpost) - Only the use of Onpost groundwater as a source of drinking water is prohibited; this potential pathway remains.
    Soil (Offpost) - Has the potential for direct contact on incidental ingestion of contaminated soil been eliminated?
    Structures - It is recommended that "or minimize" be inserted after the word "eliminate" in order to more accurately describe the situation.


ATSDR reviewed Denver's concerns and has made some changes to the wording in this Table for the following reasons:

    Groundwater (Onpost) - The Federal Facilities Agreement (EPA, 1989) not only prohibits the potable use of Onpost groundwater, but also prohibits Onpost agriculture (crops and vegetables) and the raising of livestock. Thus, human exposure to contaminated Onpost groundwater is effectively eliminated, as is the pathway.
    Soils (Offpost) - While it is unlikely that human dermal exposure or incidental ingestion of contaminated surface soils on lands owned by Shell Oil Company (those lands known to be affected by the highest levels of Offpost surface soil contamination) would be of sufficient intensity or duration to result in adverse human health effects, the revegetation provisions of Component 22 (Colorado, 1995) further ensure that no future pathway of human exposure exists on these lands. The Table was supplemented to reflect the effects of Component 22.
    Structures - Denver's suggestion to add the phrase "or minimize" was adopted and the Table changed.
  1. Shell Oil Company noted that footnote "c" was apparently missing from (what is now) Table 5A and questioned the significance of this footnote.


The letter "c" is used as a suffix for EMEG and RMEG comparison values in (what are now listed as) Tables 5A - 11 and was used as an abbreviation for the EMEG or RMEG exposure screening value for a child. Similarly the letter "a" was used as abbreviation for the exposure screening value for an adult. To clarify these tables, the suffix was replaced with the appropriate word: child or adult.

  1. The USFWS commented that the 1994 Annual Progress Report included new biomonitoring data on waterfowl, morning doves, and deer which should be considered in the Assessment and that may affect ATSDR's Conclusions and Recommendations.


The data provided by USFWS was incorporated in several sections of the Assessment. That data resulted in the creation of Table 12B and the modification of both the Conclusions and the Recommendations relating to the foodchain pathway and sampling needs.

  1. One member of the public noted that page 16 of the public comment release of the Assessment states"isolated occurrences of a few contaminants in wells probably represents localized leakage (in poorly constructed or damaged wells) of contaminants" which contradicts the page 150 statement indicating "that vertical migration of chemicals is occurring".


The respondent has compared statements made about two different aquifers. The first statement noted is made in reference to the Arapahoe Aquifer, while the second statement discusses the Denver Aquifer. No changes to these discussions is warranted.

  1. One member of the public comments that the prohibitions of use of RMA lands for residential uses, as discussed in the Summary should be supplemented by a statement indicating that portions of Section 9 will be sold off in support of building a visitor center.


As specified in the Projected Future Land Uses - Onpost section of the public health assessment, provisions of the RMA National Wildlife Refuge Act of 1992 (106 STAT 1961) provide for the disposal of approximately 815 acres located along the western side of RMA (portions of Sections 4 and 9 (T3S, R67W) and 33 (T2S, R67W) for commercial, highway, and other public uses. The surface soils of those lands are not contaminated by RMA-related contaminants at levels of health concern. No changes to the wording of this section of the Assessment are warranted.

  1. One member of the public questions whether the lands directly north of 96th Avenue will be cleaned up before the area is zoned residential or commercial?


Component 22 of the Conceptual Agreement and the Offpost ROD (Colorado, 1995; HLA, 1995) provided that Shell Oil Company and the U.S. Army agree to revegetate the approximate 160 acres located in the southeast portion of Section 14 and the southwest portion of Section 13. ATSDR is not aware of any present of future plans to modify the existing use of those lands or to apply for a zoning change.

  1. One member of the public requested clarification of statements made about the RMA Pilot Exposure Study: Part 1 (Health Outcome Data Evaluation section of the Assessment) and questioned the follow-up activities conducted.


Based upon comments supplied by the CDPHE (1994), follow-up activities were conducted to evaluate the potential exposure of area residents to groundwater concentrations of mercury.

  1. One member of the public asked why wind rose data for 1975-1979 were presented in (what is now) Figure 3? The respondent further questioned the relevance of those wind data for evaluating past, present, or future human exposures to RMA contaminants.


The 1975-1979 wind rose data is presented in the Assessment as an example of prevailing wind conditions at RMA. That information on prevailing wind conditions gives general information on the direction and frequency of potential air pathway routes.

  1. One member of the public questioned the exact location and use of the 1990 prison located south of RMA.


The prison described in the demographic information included in the Assessment is located south of RMA, between highway I-70 and the north boundary of the former Stapleton International Airport property. The 1990 Census data was used to provide an overview of the demographic character of the area.


1. No wells in the Offpost Study Area north of RMA are used for individual domestic drinking water supplies if those wells have historical contamination greater than the EPA Lifetime Health Advisory level for Diisopropylmethyl phosphonate (DIMP) of 600 ppb. Bottled water has been supplied to residents of this area by the state of Colorado if their drinking water well was found to contain a trace or more of DIMP.

2. IRAs are actions determined to be necessary and appropriate and that are implemented to expedite the mitigation of contamination prior to the selection of the final remedial actions.

3. BCSs are groundwater intercept and treatment systems installed along or near the RMA boundary. Those systems are designed to mitigate or eliminate off-site human exposure to potentially adverse levels of groundwater contamination.

4. For more detailed information on the 178 contaminated sites listed in this table the reader is referred to the Remedial Investigation Summary Report (EBASCO, 1992, Tables 1.2-2 and 2.1-1).

5. Source: Census of Population and Housing, 1990: Summary Tape File 1A (Colorado) [machine-readable data file]. Prepared by the Bureau of the Census, Washington, D.C.: The Bureau [producer and distributor], 1991.

6. The Montbello area lies within Census Tracts 83.04, 83.05, 83.06, 83.11, and 83.12.

7. The Commerce City area described by the data given in this column is that portion of Commerce City lying west of RMA and included within Census Tracts 87.03, 87.05, 87.06, 88.01, and 88.02.

8. The area described by the data given in the column is for that portion of the Offpost Study Area lying north of RMA and south of a line described by East 124th Ave., State Highway 51, and East 120th Ave., otherwise known as Census Tract 85.12.

9. The source and location descriptions for this continuation of Table 3 remain the same as for the parent table.

10. A household is an occupied housing unit, but does not include group quarters such as military barracks, prisons, and college dormitories.

11. Data derived from RMAED queries conducted on 10/15/93 for the cumulative, historical values for the interval 1985-93 and on 03/31/94, 04/26/94, and 05/03/94 for the 1990-1993 sampling events.

12. At this time there is no MCL specifically for chloroform. However, chloroform is regulated under the total trihalomethane MCL of 100 ppb.

13. The L-THA values given for these OSCHs was developed by Region 8, EPA for use within


14. Data derived from RMAED queries conducted on 04/01/94, 04/26/94, and 05/03/94.

15. At this time there is no MCL specifically for chloroform. However, chloroform is regulated under the total trihalomethane MCL of 100 ppb.

16. At this time there is no MCL specifically for chloroform. However, chloroform is regulated under the total trihalomethane MCL of 100 ppb.

17. See footnote no. 13.

18. Analyses of the mallard muscle tissue samples had not been received at the time this assessment was prepared but, given the similarity of the other test results for redhead duck and coots, it is expected that those tissue samples will also fall below the FDA Action Level.

19. Of total of 29 wells in which DIMP was detected, 10 of the detections were less than the quantification limit of the test. In those cases, the detection limit was >8ppb and the true level of DIMP contamination in those 10 wells may have been less than 8 ppb, but the test was incapable of determining the true value. Bottled water is not supplied to 4 of those 10 residences.

20. In October 1994, those 29 wells contained DIMP at levels less than 28.5 ppb and the contaminant levels detected in those wells are declining with the passage of time.

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