PUBLIC HEALTH ASSESSMENT
BRUNO COOP & ASSOCIATED PROPERTIES
BRUNO, BUTLER COUNTY, NEBRASKA
Sampling has been conducted for groundwater in public wells and one private well and for soilgas. Those sampling data and supporting site-related information suggest that contaminantshave been released to the groundwater, soil, and air. This section identifies contaminantsATSDR has selected for further evaluation in subsequent sections of this public healthassessment to determine whether exposure to them has public health significance. ATSDR'sidentification of contaminants in this section does not imply that human exposure would actuallyresult in adverse health effects.
Contaminant selection considers the following factors:
- Concentrations of contaminants in media.
- Sample locations, field data quality, and laboratory data quality.
- Relationship of concentrations to ATSDR's public health assessment comparison values.
- Community health concerns.
ATSDR also searched EPA's Toxic Chemical Release Inventory (TRI) -- a data base thatcontains information about annual releases of toxic chemicals to the environment by certainindustries -- to determine whether the inventory identified releases in the Bruno vicinity. TRIcontains no release information for the area.
The contaminants selected to be addressed further in the public health assessment are listed indata tables 1-3 (Appendix B). No analyses have been made for ethylene dibromide (EDB),which was at one time a common grain fumigant in this country. Thus, EDB is not discussed inthis document. The data tables also identify the public health assessment comparison valueATSDR used for selection. For this site, the Cancer Risk Evaluation Guide (CREG) was themost pertinent comparison value. CREGs are estimated comparison concentrations for specificchemicals based on an excess cancer rate of one in a million persons and are calculated usingEPA's cancer slope factors.
Public Wells and Water Tap Data -- 1984 thru 1989
Water samples obtained between 1984 and 1989 from the two former public wells and fromwater taps within the community have been analyzed. The laboratory data show contaminantsattributed to grain storage chemical treatment activities were found at levels that exceedATSDR's comparison values for drinking water use for CCl4, chloroform, and DCA. Maximumconcentrations of contaminants are shown in Table 1 (Appendix B). Water supplies that aretreated with chlorine often contain low levels of chloroform and other trihalomethanes, whichare a by-product of the chlorination process. Thus, chlorine treatment at one of the former wells(Well 30184) may have contributed a portion of the chloroform recorded. However, the highestlevel (93 ppb [parts per billion]) recorded for that well might also have occurred throughchlorination equipment malfunction.
Soil Gas -- 1988
A soil gas investigation for CCl4 was conducted in 1988 to aid in evaluating the lateral extent ofcontaminated groundwater and to locate the source(s) of contamination (2). Soil gas sampleswere obtained within the storage area and outward in the community. Low to moderately highconcentrations of CCl4 were shown at some locations within the storage area. Elsewhere in thatarea and out in the community, CCl4 was not found. Those data are shown in Table 2 (Appendix B).
ATSDR was unable to locate any sampling information for on-site soils and private wells or forsurface water and sediments. Monitoring wells have not been installed.
Although information is not sufficient to actually define the lateral limits of site contamination,the data ATSDR reviewed for the two new public wells and for one private well indicate that thewells are located beyond the site limit.
Public Well Data -- After 1990
The new wells brought into service in 1990 also have been sampled. Well analyses conducted in1991 and 1993 show that no CCl4, chloroform, or DCA were detected in water from either well. Bromodichloromethane (BDCM), a common trihalomethane byproduct of water supplychlorination, was present at a very low level in a sample from one of the wells in 1991 but wasnot present when sampled in 1993. Those data are shown in Table 3 (Appendix B). NDOHpersonnel reported to ATSDR that some of the other samples obtained from those wells did notcontain any of those chemicals.
Private Well Data -- 1987
One private well located outside the community in an area that is likely to represent backgroundwater quality was sampled in 1987. None of the contaminants were detected in that sample. Water quality data are not available for any other off-site private wells.
Reference documents do not contain comprehensive quality assurance information forinvestigation and sampling protocols and for laboratory analyses. In preparing this assessment,ATSDR presumed that the protocols and results are valid and used the information in itsevaluations. The reliability of the information could affect the validity of ATSDR's conclusions.
ATSDR did not observe any physical or other hazards associated with the site.
ATSDR identifies human exposure pathways by examining environmental and humancomponents that might lead to contact with contaminants. A pathway analysis considers fiveelements: a source of contamination, transport through an environmental medium, a point ofexposure, a route of human exposure, and an exposed population. Completed exposurepathways are those for which the five elements are evident and indicate that exposure to acontaminant has occurred in the past, is currently occurring, or will occur in the future. Potentialexposure pathways are those for which one or more of the elements is not clearly defined but isplausible. Potential pathways indicate that exposure to a contaminant could have occurred in thepast, could be occurring now, or could occur in the future.
Analyses suggest there are completed pathways associated with groundwater and pesticide uses. Affected populations include residents and grain storage workers. Elements of the principalcompleted pathways are summarized in Table 4 (Appendix B).
Several potential exposure pathways are plausible. The principal one is household use ofgroundwater from private wells in and near the community. Elements of the principal potentialpathway are summarized in Table 4 (Appendix B). Other potential pathways are associated withpesticide and grain use, interior air in community homes and other buildings, soil contact, andrecreation activities in the stream of Skull Creek.
Principal Completed Exposure Pathways
- Former Public Supply Wells
Analyses show that three contaminants have been present (typically at low concentrations) ingroundwater withdrawn by the two former public water supply wells -- CCl4, chloroform, andDCA. Therefore, within some part of the time between the 1940s and 1990, residents, workers,and visitors were exposed to those chemicals principally through ingestion and inhalation(showering/cooking). Exposure also occurred through skin contact.
- Grain Storage Fumigant Pathways
Spraying, pouring, or dumping fumigant chemicals used in the past to control insects androdents is believed to have resulted in exposure to persons that applied the chemicals throughinhalation, skin contact, and incidental ingestion. ATSDR was told that fumigators were "overcome" when using chemicals at storage units owned by a former operator.
Other Completed Exposure Pathways
A sample from one of the new public water supply wells has shown a very low concentration ofone chemical -- BDCM, a common by-product of water chlorination. Discussions with NDOHindicate that one or more other sample analyses did not detect any of the contaminants ofconcern. Thus, residents, workers, and visitors in the community are being exposedintermittently -- now and possibly in the future -- to low levels of chlorination by-productchemicals. This exposure pathway is unrelated to releases at the site.
Principal Potential Exposure Pathways
- Private Well Pathways
ATSDR believes private well use is the most important of the potential exposure pathways. Available data are not sufficient to evaluate the pathway.
Several vacant residences in the town and two that are adjacent to the town limits are notconnected to the public water system. When, or if, those homes are occupied and if private wellwater is used, ATSDR believes there is a potential for exposure to chemicals in groundwaterthrough ingestion, inhalation, and dermal contact.
One residential well beyond the town in an area that is likely to represent background waterquality was tested, and contaminants were not present. However, ATSDR believes that other close by residents with private wells -- especially northwest and north -- more likely could beexposed to chemicals through ingestion, inhalation, and dermal contact. The availablegroundwater data are not sufficient to identify the lateral limits of the contaminated groundwaterzone or to estimate what the current and future maximum concentrations may be.
- Soil Gas Pathway
Investigations in 1988 showed CCl4 was present in soil gas within a portion of the grain storagearea and was not found beyond the grain storage property at any of the locations tested. However, ATSDR believes soil gas might extend to some nearby residences because of (1) theclose proximity of some homes to the storage area -- particularly to the west -- and (2) gasesmight be released to soils not only where the chemicals originally were applied but alsowherever groundwater containing those chemicals migrates. Therefore, ATSDR concludes soilgas might enter and accumulate in residences (principally those with basements). If that hasoccurred or occurs in the future, occupants would be exposed through inhalation. Information isnot available to adequately evaluate the pathway.
Additional Potential Pathways
Several additional pathways plausibly connected with grain storage chemical activities have beenconsidered and are believed to be of little or no consequence either because the potentialexposure would be random or infrequent or the contaminant concentration is likely to be inconsequential.
Workers near storage units during or after fumigation, or possibly persons in the nearestresidences and businesses, potentially were exposed intermittently to chemicals principallythrough inhalation. Ambient air data are not available to evaluate that potential past exposure.
Chemicals poured into rodent holes, and possibly those used excessively to fumigate grain,would have contaminated some of the subsurface soils within the grain storage area. Thus, anyworkers -- past, present, and future -- that engage in excavation might be exposed to residuallevels of those chemicals through skin contact, inhalation, and incidental ingestion. Data are notavailable to evaluate that potential exposure.
Grain, primarily that on which liquid fumigants were poured, might have retained residual levelsof contaminants when shipped for use. Thus, consumers of grain-related products conceivablywere exposed randomly to the chemicals through ingestion. Analytical data are not available toevaluate that potential past exposure.
Persons that use private wells for irrigation (for example, lawns, crops), potentially are exposed -- past, present, future -- principally through skin contact. Well users in town are the most likelyto be subjected to exposure; farm irrigation wells may be too far from the source to be affected. Analytical data are not available to evaluate that potential exposure.
The town of Abie, located a few miles north of Bruno, has a public well system. Over anextended time, groundwater contaminants at Bruno conceivably might migrate as far as Abie. Should that happen, residents there could be exposed through ingestion, inhalation, and skincontact. However, because of dilution and chemical degradation in the groundwater system, anyresulting concentrations in the Abie system are likely to be inconsequential. No contaminantswere detected in analysis of water from Abie's wells conducted in 1991 and 1993 (3).
Surface water in the stream of Skull Creek is likely to receive contaminants contained ingroundwater discharge. ATSDR observed that the stream is not an inviting recreational mediabecause of steep, high banks and a very narrow, shallow water course. Although some childrenmight play in the stream, the events are likely to be infrequent. Also, concentrations are likely tobe very low after stream dilution. Therefore, any resulting exposures are likely to be inconsequential. Analytical data are not available to evaluate the pathway.
The contaminants of concern released into the environment at the Bruno Coop & AssociatedProperties (BCAP) site have the potential to cause adverse health effects. However, for adversehealth effects to occur the pathway for exposure must be completed. A release does not alwaysresult in exposure. A person can only be exposed to a contaminant if they come in contact withthe contaminant. Health effects resulting from the interaction of an individual with a hazardoussubstance in the environment depend on several factors. One is the route of exposure: that is,whether the chemical is breathed, consumed with food or water, or whether it contacts the skin. Another factor is the dose to which a person is exposed, and the amount of exposure dose that isactually absorbed. Mechanisms by which chemicals are altered in the environment or inside thebody, as well as the combination (types) of chemicals are also important. Once exposure occurs,characteristics such as age, sex, nutritional status, genetics, life style, and health status of theexposed individual influence how the contaminants are absorbed, distributed, metabolized, andexcreted. Together those factors and characteristics determine the health effects that may occuras a result of exposure to a contaminant. Much variation in those mechanisms exists amongindividuals.
Health guidelines provide a basis for comparing estimated exposures with concentrations ofcontaminants in different environmental medium (soil, air, water, and food) to which peoplemight be exposed. ATSDR has developed a Minimal Risk Level (MRL) for contaminantscommonly found at hazardous waste sites. The MRL is an estimate of daily exposure to acontaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs aredeveloped for different routes of exposure, like inhalation and ingestion, and for length ofexposure, such as acute (less than 14 days), intermediate (15 - 364 days), and chronic (365 daysor greater). Oral MRLs are expressed in units of mg/kg/day. MRLs are not derived for dermalexposure. The method for deriving MRLs does not include information about cancer, therefore,an MRL does not imply anything about the presence, absence, or level of cancer risk. If anATSDR MRL is not available as a health value, then EPA's Reference Dose (RfD) is used. TheRfD is an estimate of daily human exposure to a contaminant for a lifetime below which (non-cancer) health effects are unlikely to occur (6). For carcinogenic substances, EPA hasestablished the Cancer Slope Factor (CSF) as a guideline. The CSF is used to determine thenumber of excess cancers expected from exposure to a contaminant. ATSDR considers theabove physical and biological characteristics when developing health guidelines.
To link the site's human exposure potential with health effects that may occur under site-specificconditions, ATSDR estimates human exposure to the site contaminant from ingestion and/orinhalation of different environmental medium (6). The following relationship is used todetermine the estimated exposure to the site contaminant:
|ED = (C x IR x EF) / BW|
|ED = exposure dose (mg/kg/day) |
C = contaminant concentration
IR = intake rate
EF = exposure factor
BW = body weight
ATSDR uses standard intake rates for ingestion of water. The intake rate for drinking water is 2L/day for adults and 1 L/day for children. Standard body weights for adults and children are 70kg and 10 kg, respectively. The maximum contaminant concentration detected at a site for aspecific medium is used to determine the estimated exposure. Use of the maximumconcentration will result in the most protective evaluation for human health. When unknown,the biological absorption from the environmental media (soil, water) is assumed to be 100%.
Individuals were most likely exposed to multiple contaminants by ingestion of contaminatedpotable water from the former municipal water supply. However, data are very limited on thehealth effects of multiple contaminant exposure. The effects of multiple contaminant exposurecan be additive, synergistic (greater than the sum of the single contaminant exposures), orantagonistic (less than the sum of the single contaminant exposures). Also, simultaneousexposure to contaminants that are known or probable human carcinogens could increase the riskof developing cancer. ATSDR's evaluation of exposures in this public health assessment islimited to individual contaminant exposures; multiple exposures have not been evaluated.
The principal completed exposure pathways discussed are our best estimates of possiblescenarios based upon what we know about the history of the site. We do not have the air datanecessary to evaluate the possible health effects resulting from inhalation exposure in the past tocontaminants found in the old municipal wells.
ATSDR has prepared toxicological profiles for many substances found at hazardous waste sites. Those documents present data and interpret information on the substances. Health guidelines,such as ATSDR's Minimal Risk Level (MRL) and EPA's Reference Dose (RfD) and CancerSlope Factor (CSF) are included in the toxicological profiles. Those health guidelines are usedby ATSDR health professionals in determining the potential for developing adverse non-carcinogenic health effects and/or cancer from exposure to a hazardous substance. Preparers ofthis public health assessment have reviewed the profiles for the contaminants of concern (7, 8, 9)at the Bruno Coop & Associated Properties site.
Public Water System Users
ATSDR has determined that users of the old public water system may have been exposed in thepast to contaminants in the former municipal wells. Each contaminant will be discussed. Toestimate the exposure dose it was assumed that the users of the former municipal water systemwere exposed to the contaminants in the water supply on a regular basis for a maximum timeperiod of 30 years.
- Carbon Tetrachloride (7)
Carbon tetrachloride (CCl4) is a clear, man-made liquid that evaporates very easily; therefore itis often found in the environment as a gas. It has a sweet odor and it is not known if people cantaste it or, if they can, at what level. In the past, CCl4 was used as a spot remover, in fireextinguishers, and as a fumigant. These uses were discontinued in the mid-1960s. Untilrecently, CCl4 was used as a pesticide to kill insects, but this was stopped in 1986.
Approximately 85-91% of CCl4 in contaminated water entering the body via ingestion isavailable for absorption. The ingested CCl4 tends to leave the body quickly and can usually befound on the breath within a few hours. Most of the CCl4 is eliminated from the bodyunchanged, however, some may be converted to other chemicals such as chloroform which maybe toxic at sufficiently high doses. CCl4 has an affinity for body fat. Animal studies have shownthat 30-40% of CCl4 is excreted in expired air, 50-60% is excreted in feces, and low amounts areexcreted in the urine. CCl4 was detected at a maximum concentration of 40.1 parts per billion(ppb) in one of the former municipal wells water supply.
ATSDR has not developed a MRL for chronic exposure to CCl4. The chronic oral RfD for CCl4is 0.0007 mg/kg/day. The estimated exposure dose for persons possibly consuming thecontaminated water exceeds the chronic oral RfD. However, according to literature researchedby ATSDR in the development of its toxicological profile for carbon tetrachloride, adverse non-cancer health effects are not expected to occur.
No studies were found regarding carcinogenic effects in humans and animals following dermalexposure to CCl4. Occasional reports have noted the occurrence of liver cancer in personsexposed to CCl4 fumes over long periods of time. However, the evidence is much too sparse toestablish a cause-effect relationship. No studies were found regarding carcinogenic effects inhumans following oral exposure to CCl4. However, EPA has classified the substance as aprobable human carcinogen by inhalation and ingestion. Both the National Toxicology Program(NTP) and the International Agency for Research on Cancer (IRAC) has determined that thissubstance is reasonably anticipated to be a carcinogen. Based on the above worse-case scenariothere would be no apparent increased risk of cancer from chronic exposure to CCl4 at a level of40.1 ppb in contaminated groundwater.
- Chloroform (8)
Chloroform or trichloromethane is a colorless liquid with a pleasant, nonirritating odor. It has aslight, sweet taste. Nearly all chloroform made in the United States is used to produce otherchemicals. However, small amounts of chloroform are formed as an unwanted byproduct whenchlorine is added to water to destroy bacteria.
Chloroform can easily enter the body through the skin. If the water is hot enough for thechloroform to evaporate, the chemical can also be inhaled during showering or bathing activities. Inhaled and ingested chloroform quickly enters the bloodstream from the lungs and intestines. Once in the bloodstream it can be transported to other body tissues. Chloroform has an affinityfor body fat. Some of the chemical is excreted in expired air unchanged. Some of thechloroform is broken-down into bi-products which once inside susceptible cells can causeharmful effects. Some of these breakdown products are released from the body with expired air. A small portion of the breakdown products leave the body via urination and excretion.
Chloroform was detected at a maximum concentration of 93 ppb in one of the former municipalwater supply wells. The chronic oral MRL for chloroform is 0.01 mg/kg/day. The estimateddaily exposure dose for persons possibly consuming the contaminated water is below the chronicoral MRL. Therefore, exposure to the contaminant is not expected to cause adverse non-cancerhealth effects.
No studies were found regarding carcinogenic effects in humans and animals followinginhalation or dermal exposure to chloroform. Epidemiological studies support a weak butsignificant association between risks of colon, bladder and rectal cancer and water chlorinationconstituents. Although human data suggest a possible increased risk of cancer at these three sitesfrom exposure to chloroform in chlorinated drinking water, due to the fact that chloroform is thepredominant trihalomethane in drinking water, the data are too weak to support a conclusionabout the carcinogenic potential of chloroform. However, EPA has classified the substance as aprobable human carcinogen by inhalation and ingestion. Both the NTP and IRAC hasdetermined that this substance is reasonably anticipated to be a carcinogen. Based on the aboveworse-case scenario there would be no increased risk of cancer from chronic exposure tochloroform at a level of 93 ppb in the contaminated groundwater.
- 1,2-Dichloroethane (9)
1,2 Dichloroethane (DCA) is a clear, man-made liquid with a sweet taste and a pleasant smell. Itis added to leaded gasoline to remove lead, used to make vinyl chloride and several substanceswhich dissolve grease, glue, and dirt. In the past, it was found in trace amounts in products usedto clean cloth, remove grease from metal, and to break down oils, waxes, resins, and rubber. DCA tends to quickly evaporate.
DCA can enter the body through the ingestion of contaminated drinking water or via inhalationof the chemical which has been released into the air from contaminated water or soil. Animalstudies have shown that once DCA enters the body it goes to many organs but usually leaves inthe breath in one or two days. The breakdown products of DCA leave the body quickly in theurine. DCA was detected at a maximum concentration of 16 ppb in the water supply of one ofthe former municipal wells. The adverse health effects resulting from long-term exposure toDCA are unknown. Chronic health guidelines for exposure to DCA by ingestion have not beenestablished due to insufficient human exposure data. However, it is believed that adverse non-carcinogenic health effects from ingestion of DCA in the contaminated drinking water supplywould not occur since the estimated dose is below the no observed adverse effect level (basedupon animal data).
Several studies conducted using workers in the chemical industry have shown a high incidenceof brain tumors, stomach cancer, and leukemia in workers who used DCA to produce ethyleneoxide. None of these studies looked exclusively at DCA and concurrent exposure to otherchemicals and solvents may have confounded the results. Therefore, specific evidence linkinginhalation exposure to DCA with the development of cancer in humans was not found in theliterature reviewed. Little information is available concerning the development of cancer inhumans following ingestion of DCA. A statistically significant association between the presenceof DCA in drinking water and the development of colon and rectal cancer in men 55 year of ageand older has been shown. The results of the study were confounded by the fact that the menwere likely concomitantly exposed to other chemicals. No studies were found regardingcarcinogenic effects in humans following dermal exposure to DCA. EPA has classified thesubstance as a probable human carcinogen by ingestion and inhalation. Both the NTP and theIRAC have determined that this substance is reasonably anticipated to be a carcinogen. Basedon the above worse-case scenario and the resulting estimated exposure dose, there would be noapparent increased risk of cancer from chronic exposure to DCA at a level of 16 ppb in thecontaminated groundwater.
It was reported to ATSDR that fumigators were "overcome" when using chemicals at storageunits owned by a former operator. Therefore, ATSDR has determined that workers who appliedfumigants to the grain stored in the grain storage units were exposed intermittently in the past tothe chemical components of the fumigants through inhalation, dermal contact, and incidentalingestion. Due to lack of information including the concentrations of chemical componentswithin the fumigants, frequency of fumigation, and specific type of adverse effect(s) whichoccurred, ATSDR is unable to quantitatively and qualitatively evaluate these exposures.
ATSDR conducts a review of health outcome data when completed exposure pathways havebeen identified; when the toxicologic evaluation indicates the likelihood of health outcomes; andwhen the community near the site has health concerns. The evaluation of health outcome datamay give a general picture of the health of a community, or it may confirm the presence ofexcess disease or illness in a community. However, elevated rates of a particular disease maynot necessarily be caused by hazardous substances in the environment. Other factors, such aspersonal habits, socioeconomic status, and occupation, also may influence the development ofdisease. In contrast, even if elevated rates of disease are not found, a contaminant may still havecaused illness or disease.
- Cancer Surveillance, Epidemiology and End Results Program (SEER)
The National Cancer Act of 1971 mandated the collection, analysis, and dissemination of all datauseful in the prevention, diagnosis, and treatment of cancer. The act resulted in theestablishment of the National Cancer Program under which the Surveillance, Epidemiology, andEnd Results (SEER) program was developed. The SEER program which is a project of theNational Cancer Institute (NCI), collects cancer data on a routine basis from designatedpopulation-based cancer registries in various areas of the country (10 sites). Trends in cancerincidence, mortality, and patient survival in the United States as well as many other studies, arederived from this data bank. Data from all of the SEER sites are combined to estimate"national" rates for every age-race-gender-year-specific stratum. The expected number of casesfor all non-SEER sites are derived by multiplying the stratum-specific rates derived from thecombine SEER data by the populations of the non-SEER sites. Analysis of data from the SEERdatabase showed no increase in the number of new cancer cases (rectal, bladder, colon,leukemia, stomach, brain, and hepatic) for Butler County versus Nebraska and surrounding Polk,Seward, and Colfax counties.
- National Center for Health Statistics (NCHS) Mortality Data
The Compressed Mortality File (CMF) is a county level national mortality and populationdatabase spanning the years 1968-1987. The mortality database is derived from the U.S. micro-data death records for this period. Cancer mortality for the years 1979-1988 were analyzed tosee if a significant increase in cancer mortality occurred during those years. The deathsoccurring in persons 0-64 years old were evaluated for the following cancer types: leukemia,colon, kidney, rectum, stomach, bladder, hepatic, lung, and brain. The number and rate ofcancer deaths occurring in Butler county were compared to the number and rate of cancer deathsoccurring in surrounding Colfax, Polk, and Seward counties and well as the state of Nebraskaand the entire United States. The expected number of cancer cases for Butler, Seward, Colfax,and Polk counties was extrapolated using the rate for the state of Nebraska. Analysis of thesedata did not indicate any excess cancer deaths from the previous types of cancers amongresidents of Butler County.
This analysis can only serve as a descriptive tool since analysis was based on data taken fromdeath certificates. It is not necessarily indicative of the total number of people who arediagnosed with cancer. Cancer cases that occurred among persons now deceased may not behelpful in linking exposure to disease because of lack of information on exposure, possibleconfounding factors such as filling out the death certificate incorrectly, or with misinformation,and random error associated with the observation of deaths.
- Nebraska Vital Statistics Report: 1989 (3)
The report indicates in general that the number of cancer deaths in Butler county is less than theaverage number of cancer deaths in the state of Nebraska. The cancer mortality data in thisreport was not broken-down by specific cancer type and county of residence. More detail isneeded to determine if an excess number of cancer deaths by type have occurred in Butler county over time.
- Cancer Incidence and Mortality in Nebraska: 1989 (4)
The data in this report from the Nebraska Cancer Registry is not detailed enough to determine ifthere is an increase in the incidence and/or prevalence of particular cancers in Butler county.
- Can any of the contaminants in the old water supply cause cancer?
Cancer is a group of diseases characterized by rapid, uncontrolled growth of tissue thatinvades adjacent structures. This can spread to distant areas of the body. Manycancerous tumors can cause death if not adequately treated. Although malignant diseasesare grouped together as cancer, they are actually different conditions with distinct causesand outcomes. Members of the community did not report any specific cancer or cancersite during the public availability sessions for the BCAP site.
Studies in animals have shown that CCl4 given by mouth can increase the frequency ofliver tumors. Studies have not been performed to determine if breathing CCl4 causestumors in animals, or whether swallowing or breathing CCl4 causes tumors in humans,but it should be assumed that CCl4 can have these effects. EPA has determined that CCl4is a probable human carcinogen. Many of the cases of CCl4 toxicity are associated withdrinking alcohol. The frequent intake of alcoholic beverages increases the risk fromCCl4 exposure (7).
Animal studies have shown that chloroform caused liver and kidney cancer to develop inrats and rabbits given the chemical in their food or water. It is not known whether or notkidney and liver cancer will develop in humans following long-term exposure tochloroform in drinking water. Studies have shown that colon and urinary bladder cancerhas developed in humans who drank water with chlorine in it. Since chloroform is abreakdown product of chlorination, these studies suggest a possible link betweenchloroform and the development of these cancers. The Department of Health and HumanServices has determined that chloroform may reasonably be anticipated to be acarcinogen (8).
Animal studies have shown that DCA causes lung tumors in laboratory animals exposedto the chemical through the skin. Cancer has developed in animals fed large doses ofDCA. Animals may also develop cancer following inhalation exposure to the chemical. Exposure to DCA has thus far not been associated with the development of cancer inhumans. However, EPA has determined that DCA is a probable human carcinogen (9).
ATSDR has evaluated the chemicals of concern at the BCAP site for possible canceroushealth effects. Using a worse-case scenario of exposure to the individual chemicals at themaximum concentration found for a period of 30 years no apparent increased risk ofdeveloping cancer is expected to occur. However, ATSDR has not evaluated the healtheffects of exposure to combinations of chemicals because very few research data areavailable. When simultaneous exposure to multiple chemicals occurs, additive,synergistic, or antagonistic interaction among the compounds is possible. The interactionof multiple chemicals may result in an increased risk of developing cancer and otheradverse health effects.
- What non-cancer health effects can be expected to occur given past exposure to thecontaminated water?
ATSDR has evaluated the chemicals of concern at the BCAP site for possible non-cancerhealth effects. Using a worse case scenario of exposure to the individual chemicals at themaximum concentration found for a period of 30 years, no adverse non-cancer healtheffects are expected to occur. The possible adverse non-cancer health effects fromexposure to DCA could not be determined due to insufficient human exposure data.
- What is the relationship between exposure to carbon tetrachloride and the development of hepatitis?
Chemically induced hepatitis is a term defined as inflammation of the liver as a result ofexposure to a chemical (10). The liver is especially sensitive to CCl4. In mild cases theliver becomes swollen and tender, and fat tends to build up inside the tissue. In severecases, many cells may be damaged or destroyed, leading to decreases in liver function. Such effects are usually reversible if exposure is discontinued (7). Based upon the levelsfound it is unlikely that exposure to the groundwater will lead to the development of hepatitis.
- What health effects can be expected from exposure to the contaminants in the old water supply from uptake in consumable crops via irrigation?
Well users in town are the most likely to be subjected to exposure to the contaminants inthe contaminated groundwater. Farm irrigation wells may be too far from the source tobe affected. ATSDR was told that the nearest irrigation well is about three quarters of amile west of town. The most likely route of exposure to the identified contaminants ofconcern while irrigating crops is through inhalation. Acute exposure to the contaminantsat the highest levels found is not expected to cause adverse non-cancer health effects. Bioconcentration of the identified contaminants is either not significant or unlikely.