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HEALTH CONSULTATION

Air Pathway Evaluation

SIERRA ARMY DEPOT
HERLONG, LASSEN COUNTY, CALIFORNIA


VI. EVALUATION OF CANCER CASES

Evaluation of Cancer Cases: What is ATSDR's main finding?: ATSDR reviewed descriptive data analyzed by the Cancer Registry of Northern California. These data do not suggest evidence of excess cancers based on the cancer types analyzed in small area assessments for census tracts surrounding SIAD. A slight excess of leukemias (all types combined) was identified in the Susanville area for the period 1988 through 1997. ATSDR does not believe these cases are associated with air emissions from SIAD, because Susanville is more than 30 miles upwind from the installation. The data currently available from the state of Nevada do not allow for a meaningful analysis of cancer cases among Nevada residents who live downwind from SIAD.To determine whether SIAD's air emissionscause cancer among nearby residents,ATSDR not only evaluated potential airexposures (see Section V), but we alsocritically reviewed data on the number ofpeople near SIAD who have been diagnosedwith cancer. Our Division of Health Studiesreviewed trends among the cancer statistics to answer a fundamental question: Are there morecases of cancer near SIAD than expected?

We also evaluated whether the cancer registries use acceptable methods to identify and interpretall reported cancer cases. This evaluation considered two concerns expressed specifically for thearea surrounding SIAD: whether cancer cases are adequately tracked for California residents whoseek medical care in Nevada, and vice versa; and how the cancer registries interpret cases forwhich residential addresses are not reported.

The remainder of this section documents our findings. This section first presents basic facts oncancer (Section VI.A), and then gives a general summary of how we interpreted the cancer datacompiled by the California (Section VI.B) and Nevada (Section VI.C) cancer registries. SectionsVI.D and VI.E present our comments on data limitations and data quality, respectively.Recommendations are provided in Section X.

A. Introduction

"Cancer" is a group of many different diseases that cause cells to grow and multiply at abnormalrates. Different cancers are caused by different risk factors. Cancer is the second leading cause ofdeath in the United States, currently causing approximately one out of every four deathsnationwide (CDC 2002). Furthermore, roughly two out of every five Americans will bediagnosed with cancer at some time in their lives (NCI 2002).

There are numerous causes of cancer, many of which are not fully understood. Researchers often group factors that cause cancer into two broad categories–heredity and the environment (NCI 2001). Hereditary factors are genetic and therefore are present at birth. Environmental factors include a wide array of behavioral and lifestyle causes (e.g., smoking, exposure to sunlight), including exposures to cancer-causing chemicals. Although many individual causes of cancer have been identified, scientists are still learning how these various factors interact to cause different kinds of cancer. For instance, because some people may be potentially exposed to trace amounts of cancer-causing chemicals at their jobs, in their diets, and from the environment, the exact cause of a person's cancer is often not known. Furthermore, ten or more years may pass between the time that a cancer-causing exposure occurs and the time that the cancer is eventually diagnosed (ACS 2002), which complicates efforts to understand exactly which exposures may have potentially contributed to the cancer.

The community has expressed concerns about a perceived excess of cancer in the communities around the SIAD site. ATSDR's evaluation of perceived elevated types of cancer within a community involves the review of available environmental data to identify potential pathways of human exposure and the presence or absence of contaminants at or above levels of public health concern. In addition, a review of available health outcome data is also performed. In this health consultation, the health outcome data available for review consisted of descriptive data from a population-based cancer registry which was collected for purposes of cancer surveillance.

To determine whether SIAD's air emissions might be related to a perceived excess of cancercases among nearby residents, ATSDR not only evaluated potential air exposures (see SectionV), but also reviewed available health outcome data on cancer incidence within communitiesnear the SIAD. Our evaluation is based largely on data reported to the California Cancer Registry(CCR). Information from the Nevada Central Cancer Registry (NCCR) specific to thecommunities around the SIAD was not available for this consultation. The purpose of this cancerdata review is to evaluate available cancer incidence data to determine whether cancer incidencein the communities around SIAD is statistically significantly elevated.

B. Evaluation of Cancer Cases in California

The Cancer Registry of Northern California (CRNC), Region 6 of the California Cancer Registry(CCR), routinely calculates cancer incidence rates for the sixteen counties of the greater NorthernCalifornia area, including Lassen County. Regional cancer incidence data is available at thecounty level; however, the data for Lassen County is combined with that of Plumas and Modoccounties which have smaller populations (CRNC 2000). In order to evaluate cancer incidence inthe communities around the SIAD, ATSDR's review of CRNC/CCR's data is limited todescriptive analyses conducted by CRNC/CCR specific to the communities located near theSIAD site.

For this consultation, ATSDR reviewed three small area assessments for census tracts around theSIAD. Each of these assessments was performed by the CRNC/CCR. Each of the small areaassessments had been conducted by the CRNC/CCR in response to community concerns aboutthe possible health effects to Lassen County residents from potentially hazardous emissions fromthe combustion of surplus munitions at the SIAD site. It should be further noted that theCRNC/CCR assessments had been performed prior to the initiation of the environmentalmonitoring described in this health consultation. Therefore, no potential exposure pathways orpotential contaminants of concern had been evaluated or identified for the SIAD site at the timethat these small area assessments were performed. In addition, the first two assessments had beenperformed prior to ATSDR's involvement with the SIAD site.

Each of the three assessments evaluated cancer incidence for four census tracts in Lassen County,California: 040300 (Susanville), 040400 (Litchfield and Standish), 040500 (Janesville), and040600 (Wendel, Herlong, Doyle, Patton Village, and Milford). These census tracts correspondto areas surrounding the SIAD facility and encompass the populated areas south of Eagle Lake,including Susanville, southeast to Herlong and Doyle and the California/Nevada border. Thepurpose of each of the three assessments was to evaluate whether the communities around theSIAD site had statistically significant excesses of (1) childhood cancers among persons ages0 through 19 years of age; and (2) cancers selected by CRNC/CCR which had sometimes beenassociated with chemical exposures in occupational settings and which might serve as potentialsentinels of possible ambient environmental exposures. The cancers selected by CRNC/CCR asbeing sometimes associated with occupational settings included: brain and nervous systemtumors, Non-Hodgkin's lymphoma, leukemia (all types), lymphocytic leukemias, andgranulocytic/myelocytic leukemias. As noted previously, the small area assessments wereperformed prior to the environmental monitoring discussed in this health consultation and nopotential exposure pathways or potential contaminants of concern had been evaluated oridentified for the SIAD site at the time.

CRNC/CCR calculated the number of observed and expected cancer cases and calculated a 99%confidence interval (range) around the number of observed cases. To estimate the number ofcancer cases expected, 1988-1992 annual average sex-, race-, and age-specific rates of invasivecancers for all sites combined for the CRNC/CCR area were applied to the correspondingpopulation residing in that area at the time of the 1990 Census. Exact number of cases were notpresented by CRNC/CCR when small numbers were involved. This was done to maintain theconfidentially of persons reported to the CCR. The confidentiality of persons whose cancers arereported to the CCR is mandated by law and is given the highest priority of registry operations(DHS 2000).

CRNC/CCR performed the first small area assessment in April 1999 in response to communityconcern about the possible health effects to Lassen County residents from potentially hazardousemissions from the combustion of surplus munitions at SIAD. In this assessment, CRNC/CCRevaluated cancers which had been diagnosed in the years 1988 through 1996 and the years 1992though 1996. The year 1988 represents the year in which regional population-based cancerregistries in California began reporting to the CCR and 1996 was the most recent year of cancerincidence data available at the time of the assessment. The years 1992-1996 represent the mostrecent (at that time) five year period in which data were available. For the 9-year period,1988-1996, CRNC/CCR identified 11 new primary, invasive cancers initially diagnosed amongresidents 0-19 years of age whose residential address at the time of diagnosis was in census tracts040300-040600. For this period (1988-1996) ten cases of childhood cancer were expected.However, the slightly elevated number of childhood cancers observed was not statisticallysignificantly elevated (observed cases=11, expected cases=10; 99% CI: 4-23 cases). It should benoted that this analysis involved childhood cancers for all cancer sites combined and not forspecific childhood cancers sites because of small numbers of cases of specific cancer typesamong children 0-19 years of age. When CRNC/CCR evaluated cancers which had sometimesbeen associated with exposures in occupational settings, brain and nervous system tumors,leukemias (all types combined) and lymphocytic leukemias were slightly higher than expected,but none was statistically significantly elevated in the four combined census tracts.

CRNC/CCR's second assessment (dated February 2000) evaluated cancers reported to theregistry which had been diagnosed during the 10-year period 1988 through 1997 and within themost recent (as of February 2000) 5-year period, 1993 through 1997. As a result of continuedcommunity concern and to remain as responsive as possible to the community, CRNC/CCRperformed this assessment which re-analyzed the cancer registry data with new unvalidatedinformation on potential cancer cases. Prior to February 2000, the last official interstate caseshare of cancer data from the Nevada Central Cancer Registry had been received by CCR in 1997and consisted of reports of cancer cases diagnosed between the years 1988 through 1995. TheFebruary 2000 small area assessment identified a total of 14 new primary, invasive cancersamong residents ages 0-19 years of age who lived at the time of diagnosis within the four censustracts during the 10-year period 1988 through 1997. For this period (1988-1997), ten cases ofchildhood cancer were expected; however, the slight elevation in observed cancer cases for thisage group and time period was not statistically significantly elevated (observed cases=14,expected cases=10; 99% CI: 6-27 cases). The wide confidence interval reflects the small numberof cases within the census tracts. Also, in this assessment, the review of cancers sometimesassociated with exposures in occupational settings did not suggest any statistically significantexcess of cancers for the 10-year period 1988-1997 or for the 5-year period 1993-1997.

The third small area assessment (dated July 2000) for the census tracts around the SIAD wasperformed by CRNC/CCR after CCR received an official electronic interstate case share ofcancer cases from the Nevada Central Cancer Registry. These cases represented Californiaresidents who received a cancer diagnosis in the state of Nevada. The community, CCR andATSDR were concerned and interested in knowing whether the additional cancer cases fromNevada might possibly reveal elevated types of cancers among California residents living in thecensus tracts surrounding SIAD. With the third assessment, CRNC/CCR was more confident thatmost, if not all, cases from the census tracts evaluated who might have been diagnosed in Nevadawere included in the assessment. Comparison of the July 2000 assessment with the February2000 assessment suggested, however, that there was no increase in the number of primaryinvasive childhood cancers within the census tracts evaluated for the years 1988 through 1997(observed cases=14, expected cases=10.2; 99% CI: 6.0-26.6 cases). In addition, there were nostatistically significant elevations in childhood cancers in this assessment for census tract 040300(Susanville) or in the combined census tracts (040400-040600) in analyses which included orexcluded untracted cases. Untracted cases are cases for which a Post Office Box or non-UnitedStates Postal Service address was reported as the residential address at the time of diagnosis. Anuntracted address cannot be accurately assigned to a specific census tract and thus increases theuncertainty of the analysis. In addition, census tracts (040400-040600) were combined in someanalyses due to small numbers of cases within the separate census tracts. In the evaluation ofcancers sometimes associated with exposures in occupational settings, the July 2000 assessmentfound the incidence of leukemias-all types combined (for all ages) for the Susanville census tract(040300) during the years 1988 through 1997 was statistically significantly elevated (observedcases=22, cases expected=11.5; 99% CI: 11.6-37.0 cases). However, it should be noted that thisstatistically significant excess did not remain when the six cases with untracted addresses wereexcluded from the analysis. Since the category of leukemias (all types) consists of many forms ofleukemia, CRNC/CCR further evaluated the finding to determine what types of leukemia weredriving the result. They found that no leukemia subset of the analysis was statisticallysignificantly higher than expected for all four census tracts combined or for individual censustracts with or without the untracted cases. They found that lymphocytic leukemias seemed tocontribute the majority of the excess cases observed in the Susanville census tract for the years1988-1997, with acute and chronic lymphocytic leukemia accounting for the difference.However, they also found that no difference was significantly higher than expected in either theSusanville census tract or in the combined census tracts for acute or chronic lymphocytic, alllymphocytic, or all granulocytic leukemias for the periods 1988-1997 or 1993-1997.

C. Evaluation of Cancer Cases in Nevada

Noting that prevailing winds near SIAD blow the OB/OD air emissions toward the state ofNevada, ATSDR also evaluated data provided by the Nevada State Health Division (NSHD) oncancer cases east of SIAD. The most detailed information that ATSDR has examined is NSHD'srecent statewide report on cancer (NSHD 2001). This report presents a wide range of cancerstatistics, but spatial analyses are only offered at the county level. In addition, it should be notedthat this data is limited by the fact that for the years 1995 through 1999, Nevada hospitals werethe sole source of new (incident) cancer cases reported to the Nevada Central Cancer Registry(Bureau of Health Planning and Statistics 2001); therefore, some cancer types may have beenunder-reported. In addition, the possibility exists that a small number of cancers diagnosedoutside a hospital setting may not have been reported to the Nevada Central Cancer Registry inorder to be counted in either the Nevada or California cancer registries. Although air emissionsfrom SIAD clearly blow into parts of Washoe County, cancer statistics for this entire county are apoor metric for the areas downwind from SIAD. As evidence of this, ATSDR notes that thepopulation of Washoe County is 339,486 (US Bureau of the Census 2000), but fewer than 200residents live in parts of the county that are within 20 miles of SIAD. Therefore, the county-widecancer statistics are heavily skewed by the more populated areas of Washoe County (the Renometropolitan area) and offer no meaningful insights for this health consultation.

ATSDR has periodically consulted with representatives of NSHD about the availability of moredetailed cancer registry records for subsets of Washoe County. In our final communication withNSHD prior to release of this health consultation, ATSDR learned that NSHD continues to workon expanding the utility of the cancer registry for Washoe County (e.g., attempting to incorporatedata from the Pyramid Lake Indian Reservation), but has not yet compiled data that would allowATSDR to examine cancer incidence among people who live in the parts of Washoe County thatare downwind from SIAD.

In summary, the cancer incidence data ATSDR has reviewed to date do not support a meaningfulanalysis of cancer cases among Nevada residents who live downwind from SIAD. ATSDR willcomplete its cancer evaluation for these Nevada residents if NSHD can provide data that willsupport such an assessment.

D. Data Limitations

It should be noted that there are many limitations of using the descriptive data from a population-based registry. This type of health outcome data provides important information about theamount and distribution of disease within a population by person, place, and time; however, itcannot be used to identify an association between an exposure and a health outcome. In order tofully examine potential causes of cancer, more powerful analytic studies which includeinformation on potential exposures and individual risk factors would have to be applied.

The cancer registry data was collected as a means of monitoring trends in cancer incidence,treatment and prevention and for generating research hypotheses (CRNC 2000). The cancerregistry also evaluates its incidence data to help determine whether a perceived excess of cancermay be a public health concern or whether the perceived excess may be due to chance (CRNC2000). The descriptive data do not include information on important confounding factors relatedto cancer such as whether a person smoked or consumed alcoholic beverages. Information aboutthese and other individual risk factors are not available and therefore any interpretation of thedata are subject to biases related to confounding and may not provide a true indication of risk in acommunity.

Also, the patient's address recorded in the cancer registry data base is the address where thepatient lived at the time of cancer diagnosis. The data does not include information about howlong the person has lived at the reported address. Since the latency of various types of cancer canrange from approximately 10 years to a few decades, it is possible that persons may have beenpotentially exposed to substances from other residential (or occupational) locations.

In some instances, the address recorded in the cancer registry data base may not have been thepatient's actual physical address at their time of diagnosis, but instead a post office box or non-United States Postal Service (USPS) address. These are known as untracted addresses. Untractedaddresses cannot accurately be linked to a specific census tract. CCR reporting requirements urgethose who submit registry data to provide street addresses (CCR 2001), but a small percentage ofrecords in the registry contain a post office box or non-USPS address. While untracted entries incancer registries limit the utility of spatial analyses, it should be noted that CRNC/CCR didconduct and present separate analyses including and excluding the untracted entries of the data inat least the February 2000 assessment to demonstrate the potential for uncertainty attributable tothe untracted cases.

Another very important issue concerns the population estimates used in the evaluation of cancerin communities. Population estimates are used to generate the number of expected cancer casesin a specific geographic area over a specified time period. An evaluation of cancer incidence in acommunity includes the comparison of the observed and expected numbers of cancer cases overa certain time period. The population estimates used in the small area analyses reviewed arebased on the 1988-1992 annual average sex-, race-, and age-specific rates of invasive cancers forall sites combined for the CRNC/CCR area which were applied to the corresponding populationresiding in that area at the time of the 1990 Census (obtained by the CCR from the CaliforniaDepartment of Finance (DOF)). Expected numbers of cancer cases are based on the age and sexcomposition of the population; therefore, sufficient changes in the population structure over timecan potentially result in either an over- or under-estimate of cancer incidence within a specificcommunity over a specific time period. It is very important to note that CRNC/CCR clearlystated in their analysis that Lassen County estimates from the DOF indicated that between theyears 1988-1997, the overall population of Lassen County increased by more than 20% withvariation by race, sex and age. In the July 2000 assessment (CCR 2000b), CRNC/CCR noted thatduring this period, Lassen County experienced a 7% increase of residents 0-19 years of age; a33% increase of persons 20-59 years of age and a 24% increase of persons 60 years of age andabove. They further noted that among persons 20-59 years of age, the largest increases wereamong black (134% increase) and Hispanic (113% increase) males, compared to white males(14% increase).

Another issue that should be noted concerns the small number of cases within census tracts. Thesmall numbers may have been due to small populations or short time periods evaluated, whichcould fluctuate and be influenced by chance. The small area assessments reviewed for thisconsultation include small numbers of cancer cases in small geographic areas and as such havewide confidence intervals associated with them.

Another potential limitation of cancer registry data relates to the race and ethnicity of the patient.A person's race or ethnicity recorded in the cancer registry is based on information from thepatient's medical record which may not have necessarily been provided by the patient. In someinstances, information on race or ethnicity may have been provided by hospital personnel on theassumption of a person's race based on their last name or an assumed race or ethnicity of parents(CRNC 2000). Race and ethnicity are important types of information because many types ofcancers vary by race or ethnicity and misclassification of individuals by these factors canpotentially bias results. In addition, it is also important to keep in mind that variations in cancerincidence reported by cancer registry data may possibly be the result of differences in cancerscreening and registration practices as well as factors related to access to medical care or lifestyleor environmental factors. Finally, the development of cancer may also be the result of chanceoccurrences.

E. Community Concerns About Data Quality

This evaluation also considered a concern expressed specifically for the area surrounding SIAD:whether cancer cases among California and Nevada residents are appropriately reported tocancers registries within their respective state.

CRNC, Region 6 of the CCR, covers the 16 most northern California counties including LassenCounty, and therefore has the responsibility for gathering, reviewing, and interpreting cancer datafor the area near SIAD. The data in this cancer registry are constantly being updated andevaluated as new cancer data are reported.

Since 1988, CCR has gathered and managed data on cancer cases diagnosed and treated atmedical facilities throughout California. CCR's reporting system standards require medicalfacilities to submit reports that contain at least the following information on the individual withcancer: name, age, sex, type of cancer, diagnosis date, and address (CCR 2001). Severalmeasures are in place to ensure that the information provided is kept confidential. Before addingnew cancer cases into the registry, CCR personnel review new records for accuracy and verifythat they are not duplicates of existing records. These and many other quality control procedureshelp ensure the accuracy of CCR's data.

Community members expressed concern that the CCR does not account for cancer cases inCalifornia residents who are diagnosed or treated by Nevada health providers. ATSDR wasinformed by CRNC/CCR that some residents who live near SIAD receive medical care inNevada health facilities because there are no oncology related services available in LassenCounty or in nearby Modoc or Plumas counties. It should be noted, however, that California andNevada have a written agreement to share cancer data (CCR/SCR 1994). Although thisagreement does not specify how often the states share records, it is our understanding that recordshave been exchanged at least twice in the last 5 years. Before entering data provided by Nevadainto California's registry, CCR officials first carefully review the records to ensure they are notduplicates of existing registry entries and apply other relevant quality control procedures.ATSDR is satisfied that these procedures are sufficient for tracking reported cancer cases amongCalifornia residents, including those that are diagnosed or treated in Nevada. However, it shouldbe noted that for the years 1995 through 1999, Nevada hospitals were the sole source of new(incident) cancer cases reported to the Nevada Central Cancer Registry (Bureau of HealthPlanning and Statistics 2001); therefore, the possibility exists that some cancers diagnosedoutside a hospital setting may not have been reported to the Nevada Central Cancer Registry inorder to be counted in either the California or Nevada cancer registries. Overall, ATSDR foundthat the methods CCR used to collect and interpret cancer data are adequate for evaluating cancer incidence.


VII. COMMUNITY HEALTH CONCERNS

Senator Reid's original petitions asked CDC to evaluate concerns regarding health effects thatmight be related to air emissions from SIAD's waste treatment operations. CDC referred thesepetitions to ATSDR for action and follow up. The two primary community health concerns, andATSDR's response to these concerns, follow:

Concern:

Community members asked if residents in the vicinity of SIAD, both in California and Nevada, are inhaling unhealthy levels of air contaminants released from the SIAD's waste treatment operations.

ATSDR Response:

Linking observed health effects with low-level environmental exposures is extremely difficult,especially in cases where relevant data are limited or missing. In the case of SIAD, however, arecent air monitoring study collected more than 200 valid air samples to characterize air qualityduring typical waste treatment operations. Moreover, extensive modeling analyses have beenconducted to characterize air quality in locations where samples were not collected and forpollutants that were not measured. ATSDR believes the available sampling and modeling resultsprovide an adequate basis for evaluating potential health concerns.

ATSDR thoroughly reviewed the sampling and modeling data for this site and carefullyexamined whether short-term or long-term exposures to the air pollutants reach levels of publichealth concern. Using standard health consultation approaches, we found no evidence thatresidents are exposed to site-related contaminants at levels that would be associated with adversehealth effects.

ATSDR notes, however, that evaluating the potential effects of environmental contaminants onhumans involves some uncertainty. For instance, the health effects that might result fromexposure to complex mixtures of chemicals are largely not understood. Moreover, detailed dose-response data are not available for every health condition of concern and contaminant releasedfrom SIAD. Additionally, this health consultation does not consider residents' other risk factors(e.g., smoking, family history of disease, and past exposures) as possible contributing factors fortheir reported health concerns. Though these uncertainties undoubtedly exist, ATSDR's approachto evaluating the health implications of chemical exposures is generally conservative, and thisconservative evaluation compensates for some of the inherent uncertainties associated withestablishing links between exposure and adverse health outcomes.

Concern:

Community members asked if there are more cases of cancer in the areas around the SIAD, both in California and Nevada, than are to be expected.

ATSDR Response:

Both California and Nevada maintain cancer registries that are continually updated withinformation on new cancer cases, and the states share their data to ensure that the registriesproperly account for residents who receive medical care in another state. However, it should benoted that, for the years 1995 through 1999, Nevada hospitals were the sole source of new(incident) cancer cases reported to the Nevada Central Cancer Registry (Bureau of HealthPlanning and Statistics 2001); therefore, some cancers types may have been under-reported. Inaddition, the possibility exists that a small number of cancers diagnosed outside a hospital settingmay not have been reported to the Nevada Central Cancer Registry in order to be counted ineither the Nevada or California cancer registries. The cancer data for California communitiesnear SIAD have been analyzed several times in recent years. Only the July 2000 assessmentfound a statistically significant finding-elevated leukemia in the Susanville census tract, afinding that did not remain when untracted cases were removed from the analyses. We do notbelieve anyone in Susanville is exposed to air emissions from SIAD that would cause adversehealth effects, including cancer. This conclusion is based on three observations: Susanville isupwind from SIAD; during the infrequent times when winds blow from SIAD toward Susanville,air emissions would disperse to immeasurably low levels over the more than 30 miles thatseparate these locations; and levels of particulate matter in Susanville do not appear to beinfluenced by air emissions from SIAD (see Appendix C.2). It is ATSDR's opinion that theevaluations conducted thus far have shown no evidence of excess cancer among the cancersevaluated in the California communities around SIAD, with the exception of the Susanvillefinding. This opinion is however based on the review of descriptive cancer data collected for thepurposes of cancer surveillance. The data currently available to ATSDR for Nevada does notcontain enough information on where people live to support a detailed analysis of cancer casesamong Nevada residents who live downwind from SIAD. ATSDR will evaluate cancer data forthis part of Nevada, once adequate data for the areas east of SIAD are provided. However, weemphasize that our environmental evaluations found no evidence that residents of Nevada areexposed to cancer-causing chemicals at levels of health concern.


VIII. CHILD HEALTH CONSIDERATIONS

Because children often are at greater risk than adults for being exposed to toxic chemicals, andbecause 6% of the population within 20 miles of SIAD are children (age 6 and under), ATSDR'sexposure and public health evaluations specifically consider children's health issues. In general,children are more likely than adults to suffer from adverse health effects due to environmentalexposure for several reasons, such as:

  • Children's developing bodies can be particularly sensitive to toxic exposure duringcertain critical growth stages, especially when children are exposed to chemicals knownto cause developmental effects (e.g., lead).


  • Children weigh less than adults. As a result, when children and adults inhale the sameamount of chemicals, children receive a greater dose (on a pound of contaminant perpound of body weight basis) than adults. For many chemicals, this higher dose causes agreater likelihood for developing adverse health effects.


  • Because children play outdoors more than adults, they are often more likely to inhale greater amounts of airborne pollutants.

For these reasons, ATSDR specifically considered children's health issues in two critical steps ofthe public health consultation process. First, when comparing levels of air pollution to health-based comparison values (see Section V), ATSDR identified comparison values that areprotective of children's exposures and of health conditions more common in children (e.g.,asthma), to the extent they are available. For instance, ATSDR used EPA's National Ambient AirQuality Standards for particulate matter and lead when evaluating the air sampling data forSIAD. These standards were developed to protect the health of sensitive populations, includingchildren. Second, when evaluating the cancer registry data for California, ATSDR evaluatedCRNC/CCR's small area assessments which analyzed childhood cancers in Lassen Countycensus tracts around SIAD.

Therefore, ATSDR carefully evaluated the available data to identify specific children's healthissues at SIAD. Although we found that children who live near SIAD were exposed to site-related environmental contamination, the trace amounts of contaminants that children inhaledwere far below levels associated with adverse health effects. In short, ATSDR's evaluationsfound no evidence that chemicals released from the SIAD's waste treatment operationspose any health hazards for children in the area. Section X of this report includesrecommendations to ensure that no health hazards occur in the future, should waste treatmentoperations resume at SIAD.


IX. CONCLUSIONS

This health consultation evaluates potential inhalation exposures to air contaminants releasedfrom waste treatment operations at SIAD. After thoroughly evaluating environmentalcontamination and cancer registry data, ATSDR has reached the following conclusions. Refer tothe Glossary (Appendix B) for our agency's definitions of the hazard categories, which areshown in bold lettering below.

  • Evaluation of environmental data. Emissions from SIAD blow primarily in the prevailingwind direction, which is toward the east. Therefore, SIAD's air emissions rarely affect airquality in upwind communities far from the installation, like Susanville. For thedownwind communities, modeling studies and a recent sampling study indicate that thecontaminants released by SIAD disperse greatly over the distance that separates theinstallation from residential areas. Moreover, these studies suggest that residents who livenear SIAD did not breathe air contamination at levels associated with adverse healtheffects. For almost every contaminant, the estimated air quality impacts are more than100 times lower than levels of public health concern. Though the modeling studiesinvolve inherent uncertainties, ATSDR believes the modeling analyses likelyoverestimated exposure concentrations; the monitoring measurements did not show anycontaminants at levels of health concern where people live.


  • Evaluation of cancer cases. Our review of environmental data concluded that SIAD'semissions of cancer-causing chemicals were not of public health concern. Overall, thedescriptive cancer registry did not suggest evidence of excess cancers based on the cancertypes analyzed in small area assessments for census tracts surrounding SIAD. However,the exception to this finding was a slight excess of leukemias (all types combined) in theSusanville area for the period 1988 through 1997–a finding that did not remainstatistically significant when persons with post office boxes or other non-U.S. PostalService addresses were removed from the analysis. Because Susanville is more than 30miles upwind from SIAD, it is extremely unlikely that cancers among Susanvilleresidents are caused by exposure to SIAD's air emissions. The data currently availablefrom the state of Nevada do not allow for a meaningful analysis of cancer cases amongNevada residents who live downwind from SIAD. ATSDR does, however, acknowledgethe uncertainties and limitations of population-based cancer registry data.

When completing health consultations, ATSDR assigns one of five "hazard categories" to thesite based on the findings of our technical analyses. ATSDR assigns inhalation exposures toemissions from SIAD to be no apparent public health hazard, which is the hazard category weuse when community members are exposed to site-related contamination, but the exposures arenot at levels expected to cause adverse health effects.

The Public Health Action Plan (Section XI) outlines past and future actions that various agencies will take to evaluate environmental health issues related to SIAD.


X. RECOMMENDATIONS

ATSDR recommends the following future actions:

  • Environmental data. Because SIAD's major waste treatment operations no longer occur,ATSDR does not believe any further action will reduce uncertainty in our analysis.Should OB/OD operations resume at SIAD, however, ATSDR recommends that theArmy conduct routine air sampling for particulate matter in at least one residential areadownwind from the installation. Such sampling is needed for greater confidence thatshort-term peaks in particulate matter levels do not exceed levels of health concern. Thisrecommendation is made as a prudent public health measure; ATSDR has no knowledgeof whether OB/OD operations will resume at SIAD.


  • Cancer registries. When reviewing the cancer incidence data, the one statisticallysignificant finding was the excess of leukemias (all types combined) in the Susanvillearea for the period 1988 through 1997–a finding that did not remain statisticallysignificant when persons with post office boxes or other non-U.S. Postal Serviceaddresses were removed from the analysis.

XI. PUBLIC HEALTH ACTION PLAN

The Public Health Action Plan for SIAD describes specific actions that have been taken orshould be taken by parties involved with the site, including ATSDR, the Army, and the statecancer registries. The purpose of this Public Health Action Plan is to ensure that this healthconsultation produces a plan of action to mitigate and prevent harmful health effects that may beresulting from exposure to hazardous substances in the environment. The following list identifiesthe public health actions that have been completed, that are ongoing, and that ATSDRrecommends take place:

Actions Completed:

  • Contractors to the Army have collected air samples during typical OB/OD wastetreatment operations and modeled the air quality impacts from SIAD's air emissions.


  • ATSDR has toured SIAD, met with local agencies and community members, andgathered available environmental and cancer incidence data.


  • The California Cancer Registry has analyzed cancer incidence in California communitiesnear SIAD on several occasions. They also produced annual regional reports on cancerincidence. The Nevada State Health Division has published an annual report on cancerincidence, which includes county-level data for Washoe County.

Actions Ongoing:

  • The California and Nevada cancer registries continue to share information on cancercases for residents who receive medical care in medical facilities across state lines.

Recommendations for Further Action:

  • Should OB/OD waste treatment operations resume at SIAD, ATSDR recommends thatthe Army conduct routine air sampling for particulate matter in at least one residentiallocation downwind from the installation.


  • The California and Nevada cancer registries should conduct periodic monitoring ofcancer incidence in communities in the vicinity of SIAD.

XII. PREPARERS OF REPORT

Gary Campbell, Ph.D.
Environmental Health Scientist, Section Chief
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation

Jeffrey Kellam, MS
Environmental Health Scientist
Federal Facilities Assessment Branch
Division of Health Assessment and Consultation

W. Mark Weber, Ph.D.
Geologist
ERG

Patricia Price-Green
Epidemiologist
Epidemiology and Surveillance Branch
Division of Health Studies

John Wilhelmi, MS
Senior Chemical Engineer
Eastern Research Group, Inc.


XIII. REFERENCES

ACS 2002. Cancer Facts and Figures, 2002. American Cancer Society. 2002.

Army Research Laboratory 2000. COMBIC, Combined Obscuration Model for BattlefieldInduced Contaminants. August 2000.

ATSDR 1995a. Toxicological Profile for RDX. June 1995.

ATSDR 1995b. Toxicological Profile for Tetryl. June 1995.

ATSDR 1995c. Toxicological Profile for Diethyl Phthalate. June 1995.

ATSDR 1995d. Toxicological Profile for 2,4,6-Trinitrotoluene. June 1995.

ATSDR 1997. Toxicological Profile for HMX. September 1997.

ATSDR 1998. Toxicological Profile for 2,4-Dinitrotoluene and 2,6-Dinitrotoluene (Update).December 1998.

ATSDR 2000. Toxicological Profile for Hexachlorobenzene (Update). Draft for public comment.September 2000.

ATSDR 1999. Toxicological Profile for Cadmium (Update). July 1999.

ATSDR 2002. Air Comparison Values (Expires 9/30/2002). 2002.

Bjorklund et al. 1998. Open Burn/Open Detonation Dispersion Model (OBODM) User's Guide.J.R. Bjorklund, J.F. Bowers, G.C. Dodd, J.M. White. Prepared for the U.S. Army DugwayProving Ground. February 1998.

BLM 1995. BLM Manual: Interim Management Policy for Lands Under Wilderness Review.Release 8-67. Bureau of Land Management. July 5, 1995.

BLM 1997. Recreation Guide for Northeastern California and Northwestern Nevada (map).Bureau of Land Management. 1997.

Brown and Root Environmental 1995. SIAD Meteorological Monitoring Plan. Prepared byBrown and Root Environmental for the U.S. Army Environmental Center. November 1995.

Brown and Root Environmental 1996a. Health Risk Assessment for Military MunitionsTreatment Facilities at Sierra Army Depot, Herlong, California. Prepared by Brown and RootEnvironmental for the U.S. Army Environmental Center. September 12, 1996.

Brown and Root Environmental 1996b. Resource Conservation and Recovery Act EcologicalRisk Assessment at Sierra Army Depot, Herlong, California. Prepared by Brown and RootEnvironmental for the U.S. Army Environmental Center. April 1996.

Bureau of Health Planning and Statistics 2001. M. Hemmings and W. Yang. Nevada Report onCancer, 1995-1999. 2001.

CARB 2000. California Ambient Air Quality Data: 1980-1999. California Air Resources Board.CD Number PTSD-00-013-CD. November 2000.

CARB 2002. California Emission Inventory Data (last updated October 8, 2000). Emissionsinventory data downloaded from the California Air Resources Board's Web page. Site lastaccessed August 9, 2002.

CCR 1999. Letter from Sharan Campleman (CCR Region 6) to local resident. Initial review ofcancer data: 1988-1996. April 1999.

CCR 2000a. Letter from Sharan Campleman (CCR Region 6) to local resident. Review of cancerdata for census tracts surrounding SIAD: 1988-1997 and 1993-1997. February 2000.

CCR 2000b. Letter from Sharan Campleman (CCR Region 6) to ATSDR. Review of cancer datafor census tracts surrounding SIAD: 1988-1997 and 1993-1997. July 2000.

CCR 2001. Cancer Reporting in California: Abstracting and Coding Procedures for Hospitals.Volume One, Sixth Edition. California Cancer Registry. October, 2001.

CCR/SCR 1994. Inter-State Cancer Case-Sharing Agreement. California Cancer Registry andState of Nevada, Statewide Cancer Registry. January 1994.

CDC 2002. Preventing and Controlling Cancer: Addressing the Nation's Second Leading Causeof Death. Centers for Disease Control and Prevention. 2002.

CRNC 2000. Campleman SL, Dryden M. Cancer in Northern California, 1988-1997. CancerRegistry of Northern California, Chico, CA. June 2000.

DEIR 2000. Draft Environmental Impact Report: Off-Site Hazardous Waste Facility PermitApplication. Prepared by the California Environmental Protection Agency Department of ToxicSubstances Control, TetraTech NUS, and Hazardous Waste Remedial Action Program(HAZWRAP). August 2000.

DHS 2000. Morris CR, Cohen R, Perkins CI, Allen M, Schlag R, Wright WE. Cancer inCalifornia:1988-1997. Sacramento, CA: California Department of Health Services, CancerSurveillance Section. June 2000.

EPA 1986. INPUFF 2.0 - A Multiple Source Gaussian Puff Dispersion Algorithm. User's Guide(abbreviated). U.S. Environmental Protection Agency. EPA/600/8-86/024. August 1986.

EPA 1987a. User's Guide to the Rough Terrain Diffusion Model (RTDM), Rev 3.20. U.S.Environmental Protection Agency. July 1987.

EPA 1987b. Health Advisory for Nitrocellulose. U.S. Environmental Protection Agency, Officeof Drinking Water. 1987.

EPA 1992. Screening Procedures for Estimating the Air Quality Impact of Stationary Sources,Revised. U.S. Environmental Protection Agency. Document number EPA-454/R-92-019.October 1992.

EPA 1998. Emission Factors for the Disposal of Energetic Materials by Open Burning and OpenDetonation (OB/OD). U.S. Environmental Protection Agency. EPA/600/R-98/103. August 1998.

EPA 1996. AP-42 Compilation of Air Pollutant Emission Factors: Wildfires and PrescribedBurning. U.S. Environmental Protection Agency. October 1996.

EPA 1999. Compendium of Methods for the Determination of Inorganic Compounds in AmbientAir. U.S. Environmental Protection Agency. EPA/625/R-96/010a. June 1999.

EPA 2001. 1999 Toxics Release Inventory, Public Data Release: State Fact Sheets. U.S.Environmental Protection Agency. EPA 260-F-01-001. April 2001.

EPA 2002a. Air emissions data accessed from the U.S. Environmental Protection Agency'sToxic Release Inventory database (www.epa.gov/tri). Data last queried on August 9, 2002.

EPA 2002b. Air emissions and ambient air monitoring data from the U.S. EnvironmentalProtection Agency's Aerometric Information Retrieval System (www.epa.gov/air/data/index.html). Data lastqueried on August 9, 2002.

EPA 2002c. List of Designated Reference and Equivalent Methods. U.S. EnvironmentalProtection Agency. July 1, 2002.

EPA 2002d. 2000 Toxics Release Inventory Data Release: Questions and Answers. U.S.Environmental Protection Agency. May 29, 2002.

EPA 2002e. Third External Review Draft of Air Quality Criteria for Particulate Matter (April,2002). U.S. Environmental Protection Agency. EPA/600/P-99/002aC. April, 2002.

EPA, not dated. 1999 Toxic Release Inventory: California State Fact Sheet. U.S. EnvironmentalProtection Agency. Publication date not specified on fact sheet; hard copies of fact sheet werereportedly available in 2001 (www.epa.gov/tri).

Holsey 2003. Written correspondence from David Holsey (Sierra Army Depot) to John Wilhelmi(Eastern Research Group, Inc.). October 8, 2003.

Long 2002. Written correspondence from Gene Long (Sierra Army Depot) to John Wilhelmi(Eastern Research Group, Inc.). April 9, 2002.

NCI 2001. Cancer Facts: Cancer Clusters. National Cancer Institute. November 19, 2001.

NCI 2002. SEER Cancer Statistics Review, 1973-1999. National Cancer Institute. Editors: RiesLAG, Eisner MP, Kosary CL, Hankey BF, Miller BA, Edwards BK. 2002.

NDEP 2001. Ambient Air Quality Trends: 1989-2000. State of Nevada Department ofConservation and Natural Resources, Division of Environmental Protection, Bureau of AirQuality. 2001.

Reno Gazette-Journal 2000. Army depot sometimes violates own rules on destroying ordnance.Frank X. Mullen Jr. Reno Gazette-Journal. February 21, 2000.

Reno Gazette-Journal 2001a. Depot burning blocked. Munitions: Lassen County officials rejectSierra Army Depot's air pollution exemption. Frank X. Mullen Jr. Reno Gazette-Journal.September 2001.

Reno Gazette-Journal 2001b. Study: Sierra Army Depot Is California's Top Polluter. Frank X.Mullen Jr. Reno Gazette-Journal. April 25, 2001.

Sacramento Bee 2001. Lassen base tops toxics list: The Army depot may face tougher pollutionrequirements to get state and federal permits. Jane Braxton Little. Sacramento Bee. April 23,2001.

TetraTech NUS 2000. Ambient Air Monitoring Plan: Open Burning/Open Detonation TreatmentFacilities at Sierra Army Depot. TetraTech NUS, Inc., and Advanced Infrastructure ManagementTechnology. July 2000.

TetraTech NUS 2001. Draft Final Ambient Air Monitoring Report: Open Burning/OpenDetonation Treatment Facilities at Sierra Army Depot. TetraTech NUS, Inc., and AdvancedInfrastructure Management Technology. April 2001.

US Bureau of the Census 2000. Census of Population and Housing: Summary Tape File. U.S.Department of Commerce. 2000.

WCDHD 2002. 2001 Washoe County Air Quality Data. Washoe County District HealthDepartment. Report downloaded from district's Web page, July 2002.

Zschiesche et al. 1992. Exposure to soluble barium compounds: an interventional study in arcwelders. W. Zschiesche, KH Schaller, D Weltle. Int Arch Occup Environ Health 64(1):13-23.


TABLES

Table 1. Contaminants with More than 10 Pounds of Air Emissions Per Year from SIAD's OB/OD Operations

Metals (and Inorganic Materials)

Aluminum
Antimony
Barium
Chromium (trivalent)
Chromium (hexavalanet)

Copper
Fiberglass
Hydrogen chloride
Iron
Lead

Manganese
Nickel
Particulate matter
Zinc

Explosives, Propellants, and Fillers

2,4,6-Trinitrotoluene
2,4-Dinitrotoluene
2,6-Dinitrotoluene
2-Nitrodiphenylamine
Cryolite
Dibutyl phthalate

Diethyl phthalate
Diphenylamine
Ethyl centralite
HMX*
Nitrocellulose
Nitroglycerin

Nitroguanidine
PETN**
RDX***
Tetryl
Triacetin

OB/OD Chemical Byproducts

1,3-Butadiene
Methylene bisphenol****
2-Methylnaphthalene
2-Methylphenol
2-Nitrophenol
4-Nitrophenol
µ,µ-Dimethylphenethylamine
Ammonia
Mixed aromatic compounds
Benzene
Benzo(b)fluoranthene
bis(2-ethylhexyl)phthalate

Butylbenzyl phthalate
Carbon monoxide
di-n-Octyl phthalate
Dibenzofurans
Ethylbenzene
Fluoranthene
Hexane
Hydrogen cyanide
Methane
N-Nitrosodiphenylamine
Naphthalene

Nitric oxide
Nitrogen dioxide
Mixed olefins
Mixed paraffins
Phenanthrene
Phenol
Pyrene
Styrene
Sulfur dioxide
Toluene
Xylenes

Notes:

Data source: Brown and Root Environmental 1996a.
* HMX =cyclotetramethylenetetranitramine
** PETN = pentaerythritol tetranitrate
*** RDX = cyclotrimethylenetrinitramine
**** The full chemical name for "methylene bisphenol" is 2,2'-methylene-bis-(4-methyl-6-t-butyl-phenol).


Table 2. Emissions Data SIAD Reported to EPA's Toxic Release Inventory

Chemical Emissions (in pounds per year)
SIAD's Original Submission for 1999 SIAD's Revised Submission for 1999 Submission for 2000
Aluminum (fume or dust) 4,120,000 22,283 24,407
Chromium Not reported 5 5
Copper 1,042,000 7,887 2,913
Di-butyl phthalate Not reported 250 250
Dinitrotoluene isomers Not reported 250 250
Dioxin-like compounds Not reported Not reported 0.00080
Hydrogen cyanide 37,000 Not reported Not reported
Lead 29,200 250 250
Manganese Not reported 5 10
Nickel 16,400 0 Not reported
Nitroglycerin Not reported 0 0
Styrene 14,000 Not reported Not reported
Zinc (fume or dust) 131,639 255 255

Notes:

Data source: EPA 2002a.
TRI data are self-reported; the accuracy of SIAD's release data is not known.
For reporting year 1999, SIAD has certified that the revised data are representativeof actual conditions, and the emissions data documented in the revised submissionreplaced the data reported in the original submission.
Releases of zero pounds suggest that SIAD manufactured, processed, or otherwiseused the chemical in large enough quantities to trigger TRI reporting, but none(or less than 0.5 pounds per year) of the chemical was estimated as being releasedto the air.
"Not reported" means SIAD did not submit a reporting form for the year of interest.SIAD is not required to submit reporting forms for chemicals that do not meetreporting thresholds.


Table 3. Estimated Ambient Air Concentrations of Metals and Inorganic Compounds
(See footnotes at end of table for explanation of contents)

Contaminant Estimated Annual Average Concentration for Maximally Impacted Residential Location in California (µg/m3) Estimated Annual Average Concentration for Maximally Impacted Residential Location in Nevada (µg/m3) Health-Based Comparison Value (µg/m3) Type of Comparison Value
Aluminum 2.8 1.4 3.7 RBC-n
Antimony 0.00055 0.00044 1.5 RBC-n
Arsenic 0.000000045 0.0000000052 0.0002 CREG
Barium 0.0066 0.0014 0.51 RBC-n
Beryllium 0.000000027 0.0000000031 0.0004 CREG
Cadmium 0.00000083 0.000000096 0.0006 CREG
Chromium (III) 0.000056 0.000046 5,500 RBC-n
Chromium (VI) 0.0000062 0.0000051 0.00008 CREG
Copper 0.31 0.25 150 RBC-n
Fiberglass 0.2 0.16 5,000 NIOSH-REL
Hydrogen chloride 3.3 0.56 20 RfC
Iron 3.4 2.8 1,100 RBC-n
Lead 0.082 0.0062 1.5 NAAQS
Manganese 0.016 0.013 0.04 EMEG (chronic)
Nickel 0.0023 0.0019 0.2 EMEG (chronic)
Selenium 0.00000015 0.000000017 18 RBC-n
Zinc 0.047 0.0039 1,100 RBC-n

Notes:

Source of estimated concentrations: Appendix 3-5 in Brown and Root Environmental 1996a.
The maximally impacted residential location in California and Nevada were SkedaddleRanch and Flanigan, respectively.
Ambient air concentrations lower than their corresponding comparison values aregenerally considered to be safe and not expected to cause harmful health effects(see Section IV.B). The lowest, or most conservative,comparison value was selected for all contaminants, considering those publishedfor cancer and non-cancer endpoints. Appendix A definesthe abbreviations used in the "Type of Comparison Value" field.
Concentrations of metals listed in this table likely overstate actual ambientair concentrations, as Appendix D.1.1 describes.
The comparison value used for fiberglass is a Recommended Exposure Limit fortotal fibrous glass particulates published by the National Institute for OccupationalSafety and Health in 1977.


Table 4. Estimated Ambient Air Concentrations of Explosives, Propellants, and Fillers
(See footnotes at end of table for explanation of contents)

Contaminant Estimated Annual Average Concentration for Maximally Impacted Residential Location in California (µg/m3) Estimated Annual Average Concentration for Maximally Impacted Residential Location in Nevada (µg/m3) Health-Based Comparison Value (µg/m3) Type of Comparison Value

Chemicals for which health-based comparison values are available

2,4,6-Trinitrotoluene 0.00034 0.00019 0.21 RBC-c
2,4-Dinitrotoluene 0.00014 0.000077 7.3 RBC-n/PRG
2,6-Dinitrotoluene 0.00014 0.000077 3.7 RBC-n/PRG
Dibutyl phthalate 0.0013 0.00013 370 RBC-n/PRG
Diethyl phthalate 0.0003 0.0015 2,900 RBC-n/PRG
Diphenylamine 0.000071 0.000013 91 RBC-n/PRG
Hexachlorobenzene 0.000000094 0.0000011 0.002 CREG
HMX 0.00032 0.000086 180 RBC-n
Nitroglycerin 0.002 0.00023 0.45 RBC-c
Nitroguanadine 0.00099 0.000064 370 PRG
RDX 0.00043 0.0002 0.057 RBC-c
Tetryl 0.000032 0.00008 37 RBC-n/PRG

Chemicals for which no health-based comparison values are available

2-Nitrodiphenylamine 0.000065 0.0000046 NA NA
Cryolite 0.000033 0.0000030 NA NA
Ethyl centralite 0.000065 0.0000047 NA NA
Nitrocellulose 0.0041 0.00096 NA NA
PETN 0.000047 0.000057 NA NA
Triacetin 0.00011 0.000019 NA NA

Notes:

Source of estimated concentrations: Appendix 3-5 in Brown and Root Environmental 1996a.
The maximally impacted residential location in California and Nevada were SkedaddleRanch and Flanigan, respectively.
Ambient air concentrations lower than their corresponding comparison values aregenerally considered to be safe and not expected to cause harmful health effects(see Section IV.B). The lowest, or most conservative,comparison value was selected for all contaminants, considering those publishedfor cancer and non-cancer endpoints. Appendix A definesthe abbreviations used in the "Type of Comparison Value" field.
The modeled concentrations of chemicals listed in this table likely overstateactual ambient air concentrations, as AppendixD.1.1 describes.


Table 5. Estimated Ambient Air Concentrations of OB/OD Chemical By-Products
(See footnotes at end of table for explanation of contents)

Contaminant Estimated Annual Average Concentration for Maximally Impacted Residential Location in California (µg/m3) Estimated Annual Average Concentration for Maximally Impacted Residential Location in Nevada (µg/m3) Health-Based Comparison Value (µg/m3) Type of Comparison Value

Chemicals for which health-based comparison values are available

1,1,1-Trichloroethane 0.000000012 0.00000019 3,800 EMEG (intermediate)
1,3,5-Trinitrobenzene 0.0000011 0.00000089 110 RBC-n/PRG
1,3-Butadiene 0.00004 0.000033 0.004 CREG
1,4-Dichlorobenzene 0.00000078 0.00000063 600 EMEG (chronic)
2-Methylphenol 0.0000022 0.0000018 180 RBC-n/PRG
4-Nitrophenol 0.0000026 0.0000021 290 RBC-n
Acenaphthalene 0.0000012 0.00000097 220 RBC-n
Acetophenone 0.00000049 0.0000004 0.021 RBC-n
Ammonia 0.00088 0.0007 100 RfC
Anthracene 0.00000058 0.00000047 1,100 RBC-n/PRG
Benz(a)anthracene 0.00000021 0.00000017 0.0086 RBC-c
Benzene 0.0007 0.00056 0.1 CREG
Benzo(a)pyrene 0.000022 0.0000015 0.00092 PRG
Benzo(b)fluoranthene 0.0000017 0.0000014 0.0086 RBC-c
Benzo(k)fluoranthene 0.0000013 0.0000011 0.086 RBC-c
Benzyl alcohol 0.00000036 0.00000029 1,100 RBC-n/PRG
Bis(2-ethylhexyl)phthalate 0.0000074 0.000006 0.45 RBC-c
Butyl benzyl phthalate 0.0000024 0.0000028 730 RBC-n/PRG
Carbon monoxide 0.15 0.12 10,000 NAAQS
Carbon tetrachloride 0.000000025 0.00000052 0.07 CREG
Chlorobenzene 0.000000047 0.00000077 62 RBC-n/PRG
Chloroform 0.00000014 0.0000024 0.04 CREG
Chrysene 0.00000064 0.00000052 0.86 RBC-n
Di-n-octyl phthalate 0.0000093 0.0000076 73 RBC-n
Dibenz(a,h)anthracene 0.0000012 0.00000025 0.00086 RBC-c
Dibenzofurans 0.0000023 0.0000017 15 RBC-n/PRG
Dimethylphthalate 0.00000095 0.00000077 37,000 RBC-n/PRG
Dimethylphenethylamine 0.0000028 0.0000022 3.7 PRG
Ethylbenzene 0.000066 0.000054 4,300 EMEG (intermediate)
Fluoranthene 0.0000021 0.0000017 150 RBC-n/PRG
Fluorene 0.00000083 0.00000067 150 RBC-n{RG
Hexane 0.000052 0.000042 200 RfC
Hydrogen cyanide 0.0097 0.0079 3 RfC
Methylene chloride 0.000000085 0.0000014 3 CREG
N-Nitrosodiethylamine 0.00000033 0.00000027 0.00002 CREG
N-Nitrosodiphenylamine 0.000037 0.0000043 1.3 RBC-c
Naphthalene 0.000037 0.000033 3 RfC
Nitric oxide 0.17 0.02 370 RBC-n
Nitrogen dioxide 0.074 0.011 100 NAAQS
Phenol 0.00015 0.000046 2,200 RBC-n/PRG
Pyrene 0.0000018 0.0000016 110 RBC-n/PRG
Styrene 0.0029 0.0023 300 EMEG (chronic)
Sulfur dioxide 0.032 0.012 80 NAAQS
Tetrachloroethylene 0.000000012 0.00000019 270 EMEG (chronic)
Toluene 0.00043 0.00035 300 EMEG (chronic)
Trichloroethylene 0.00000021 0.0000034 40 RfC
Xylenes (mixed isomers) 0.00037 0.0003 400 EMEG (chronic)

Chemicals for which no health-based comparison values are available

1-Nitropyrene 0.00000058 0.00000012 NA NA
Methylene bisphenol 0.000019 0.0000022 NA NA
2-Methylnaphthalene 0.0000048 0.0000039 NA NA
2-Nitronaphthalene 0.0000014 0.0000003 NA NA
2-Nitrophenol 0.000036 0.0000019 NA NA
Methane 0.2 0.018 NA NA
Phenanthrene 0.000003 0.0000024 NA NA
Picric acid 0.00000014 0.00000011 NA NA

Notes:

Source of estimated concentrations: Appendix 3-5 in Brown and Root Environmental 1996a.
The maximally impacted residential location in California and Nevada were SkedaddleRanch and Flanigan, respectively.
Ambient air concentrations lower than their corresponding comparison values aregenerally considered to be safe and not expected to cause harmful health effects(see Section IV.B). The lowest, or most conservative,comparison value was selected for all contaminants, considering those publishedfor cancer and non-cancer endpoints. Appendix A definesthe abbreviations used in the "Type of Comparison Value" field.
The modeled concentrations of chemicals listed in this table likely overstateactual ambient air concentrations, as AppendixD.1.1 describes.


FIGURES

Location of Sierra Army Depot
Figure 1. Location of Sierra Army Depot

Immediate Vicinity of Sierra Army Depot
Figure 2. Immediate Vicinity of Sierra Army Depot

Wind Rose for Meteorological Data Collected at the Incinerator in 1996
Figure 3. Wind Rose for Meteorological Data Collected at the Incinerator in 1996

Wind Rose for Meteorological Data Collected at the OB/OD Break Shack in 1995
Figure 4. Wind Rose for Meteorological Data Collected at the OB/OD Break Shack in 1995

Annual Amount of Waste Material Treated at SIAD, by Fiscal Year
Figure 5. Annual Amount of Waste Material Treated at SIAD, by Fiscal Year

Pollutants Released to the Environment after Open Detonation of Explosive Materials
Figure 6. Pollutants Released to the Environment after Open Detonation of Explosive Materials

Influences of Forest Fires on Average PM10 Concentrations in Residential Areas
Figure 7. Influences of Forest Fires on Average PM10 Concentrations in Residential Areas

Average PM10 Concentrations Measured during the 2000 Sampling Program
Figure C-1. Average PM10 Concentrations Measured during the 2000 Sampling Program

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