PUBLIC HEALTH ASSESSMENT
TRIUMPH MINE TAILINGS PILES
HAILEY, BLAINE COUNTY, IDAHO
The tables in this section list the contaminants of concern. We evaluate these contaminants inthe subsequent sections in the Public Health Assessment and determine whether exposure tothem has public health significance. ATSDR selects and discusses these contaminants basedupon the following factors:
- Concentrations of site contaminants,
- Field data quality, laboratory data quality, and sample design,
- Comparison of site contaminant concentrations with health assessment comparison valuesfor (1) non-carcinogenic endpoints and (2) carcinogenic endpoints, and
- Community health concerns.
In the data tables that follow the listing of a contaminant does not mean that it will cause adversehealth effects from exposures. Instead, the list indicates which contaminants will be furtherevaluated in the Public Health Assessment.
Comparison values for the public health assessment are contaminant concentrations in specificmedia that are used to select contaminants for further evaluation. Those values includeReference Dose Environmental Media Evaluation Guides (RMEG), Environmental MediaEvaluation Guides (EMEG), Cancer Risk Evaluation Guides (CREG), Lifetime HealthAdvisories (LTHA), and Maximum Contaminant Levels (MCL). An RMEG is an evaluationguideline calculated from EPA's Reference Dose. EPA's reference dose is an estimate of thedaily exposure to a contaminant that is unlikely to produce adverse health effects. An EMEG isa media specific screening value used to select a chemical contaminant of potential healthconcern at hazardous waste sites. A CREG is a media-specific screening value derived byATSDR from EPA cancer slope factors. A CREG represents the estimated contaminantconcentration based on one excess cancer in a million persons exposed to that contaminant over alifetime. An LTHA represents a level of a contaminant in drinking water at which adversenoncarcinogenic health effects would not be anticipated to occur during a lifetime of exposure(70 years) with a margin of safety. An MCL represents a contaminant concentration that EPAdeems protective of public health (considering the availability and economics of water treatmenttechnology) over a lifetime (70 years) at an exposure rate of two liters per day.
ATSDR reviewed information collected by government agencies on the presence ofcontaminants in the environment in the vicinity of the site. Results of environmental monitoring conducted are discussed below.
In 1986, the IDEQ collected a well water sample from a ranch about 3/4 of a mile downgradientto the Triumph Mine Tailings Site. Analytical results from the well sample did not containmetals at levels above federal drinking water standards (1).
In 1988, the IDEQ found elevated concentrations of arsenic, iron, manganese, and zinc in surface water collected from a drainage ditch near the lower tailings pile.
In 1990, two Triumph community wells (one upgradient and one downgradient of the tailingspiles), ranging in depth from 55 to 60 feet, were sampled by the community water service. Neither well sample exhibited concentrations of metals that exceeded federal drinking waterstandards (1).
In October 1990, in accordance with the Comprehensive Environmental Response,Compensation, and Liability Act (CERCLA), EPA initiated a site inspection at the TriumphMine Tailings Site to investigate potential health and environmental threats associated with the two large tailings piles. The sampling efforts were directed toward determining potential human exposure pathways and releases to the environment. The results of the investigation indicatedthat elevated concentrations of arsenic, cadmium, copper, lead, manganese, mercury, selenium,silver, vanadium, and zinc were present in samples of surface and subsurface tailings, surfacerunoff, wetland surface waters, residential soil samples, and downwind air samples. In addition,elevated levels of copper, lead, and zinc were found in downgradient drinking water wells,although only lead was present at levels exceeding the federal Maximum Contaminant Level(MCL) (in the downgradient community well) (1).
In October 1991, EPA's Superfund Removal Program tasked the Region X Technical AssistanceTeam (TAT) to conduct a site assessment of the Triumph Mine Tailings Site. The siteassessment was intended to identify site contamination which could pose an immediate threat tohuman health and the environment and to determine if expedited removal actions were needed toeliminate such threats (1).
In December 1991, TAT performed Phase I of the site assessment, during which groundwater,mine waste, process tailings, mine foundation, and residential surface soil samples werecollected. Analytical results of these samples indicated elevated concentrations of 1) arsenic andzinc in water draining from a mine portal; 2) antimony, arsenic, cadmium, copper, lead, mercury,nickel, selenium, silver, and zinc in mine waste and process tailings; and 3) antimony, arsenic,cadmium, copper, lead, mercury, nickel, selenium, silver, and zinc in residential surface soils. The highest levels of metals were detected in a soil sample collected from the remains of themine process foundation. No metals were detected at levels exceeding federal drinking waterstandards in groundwater samples from community and private drinking water wells (1).
In March 1992, the TAT returned to Triumph to conduct Phase II of the site assessment. TheTAT collected additional community well samples to assess an apparent seasonal fluctuation ingroundwater metal concentrations. The TAT also collected residential soil samples, surface soilsamples from unimproved roads, sediment samples from the surrounding wetland areas, andsubsurface waste samples from the two mine tailings piles. Analytical results from this phase ofthe assessment indicated lead concentrations above the federal MCL in one groundwater sample. Elevated concentrations of arsenic, beryllium, cadmium, lead, nickel, and zinc were detected inthe residential soil sample (as compared to background soil levels). In the road soil samples,elevated levels of antimony, arsenic, cadmium, copper, lead, nickel, selenium, silver, and zincwere found. Wetland sediment samples contained elevated concentrations of antimony, arsenic,cadmium, copper, lead, mercury, nickel, selenium, silver, and zinc (1).
In April and June 1992, the TAT again returned to Triumph to conduct Phase III of the siteassessment, which involved the collection of additional groundwater samples, indoor dustsamples, and soil and mine tailing samples for an EPA-sponsored bioavailability study. Thisstudy will be described in the Toxicological Implications Section of this public healthassessment. Groundwater samples from the tailings piles boreholes showed concentrations ofarsenic, cadmium, lead, silver, and zinc in excess of either primary or secondary federal MCLs. However, groundwater samples from community drinking water wells did not exceed primary orsecondary federal drinking water samples. Dust samples collected from vacuum cleaner bags ofseveral Triumph residences indicated elevated concentrations of antimony, arsenic, cadmium,copper, lead, mercury, silver, and zinc (1).
In June 1992, EPA's Removal Program initiated an Expedited Risk Assessment and aBioavailability Study in order to better determine whether removal actions were needed to reducepotential human health risks associated with the site (1). The Expedited Risk Assessment was finalized in May 1993.
In May 1993, EPA conducted additional sampling at the Triumph Mine Tailings Site, primarilyto determine whether a groundwater metals plume existed beneath the site and to assist indesigning future groundwater investigations. The following media were sampled: shallowgroundwater, community well water, surface water, sediment, surface soil, and subsurface soil. No contaminants were detected in samples from the community drinking water wells at levelsexceeding federal drinking water standards. Several metals were found in the shallowgroundwater samples in excess of federal drinking water standards; however, no groundwatermetals plume was evident. Elevated levels of antimony, arsenic, barium, cadmium, cobalt,copper, lead, manganese, nickel, selenium, and zinc were present in water samples from sitewetlands and/or other site surface waters (e.g., tailings pile pond, drainage ditch, upper spring). However, only barium, chromium, and manganese were detected in the surface water sample from the river.
Samples of sediment from the river and site wetlands contained elevated levels of arsenic, lead,silver, and zinc, while the wetland sediment samples also had elevated levels of beryllium,cadmium, chromium, copper, mercury, nickel, selenium, thallium, and zinc. The single surfacesoil sample and two subsurface soil samples, which were believed to have been collected frombetween the tailings piles, contained elevated levels of arsenic, chromium, copper, lead, nickel,and zinc. The contaminant levels were generally higher in the surface samples than in thesubsurface samples (5).
Table 1 presents the maximum concentrations of each metal detected in mine tailings, residentialsoil, residential indoor dust, and roadway soil over the course of the IDEQ and EPA samplinginvestigations to date. Table 2 presents the maximum concentrations of metals detected inwetland sediments, sediments of the East Fork of the Big Wood River, and other surface water. Table 3 presents the maximum level of metals measured in water samples from site wetlands, theriver, and other site surface waters (such as ponds on the tailings piles, springs, and surfacerunoff areas). Table 4 presents the maximum level of metals detected in sediments from surfacewaters such as site wetlands, the river, and other site surface water drainage areas. Table 5indicates contaminants that have been detected in high volume air samples downwind of theresidences.
|MAXIMUM CONCENTRATION(ug/L)||Comparison Value|
|CommunityDrinking Water Wells||Private Wells||ug/L||Source|
|Barium||58.1 - 67.4 J||68.2||66.6 J||700||RMEG|
|Selenium||1.8 J - 2.6 J||3.4||2.7 J||30||EMEG|
|Thallium||ND - 2.8 J||2.8||2.9||0.4||LTHA|
|Vanadium||ND - 5.6 J||6.9||6.5 J||20||LTHA|
|Zinc||ND - 6.8 J||411||1,480||2,000||LTHA|
|ND - not detected; J - estimated value|
|MAXIMUM CONCENTRATION (ug/L)||Comparison Value|
|Barium||ND||63.9 J||41.3 J||50.8 J||700||RMEG|
|Cadmium||2.3 J||739||(2.3 J)||11.7||7||EMEG|
|Lead||1.2 J||116||2.1 J||31.6||NONE||NONE|
|ND - not detected; J - estimated value|
|MAXIMUM CONCENTRATION (mg/kg)||Comparison Value|
|Antimony||ND||138 J||ND||105 J||20||RMEG|
|Arsenic||ND - 14.0||10,200||184||30,600||0.02||CREG|
|Beryllium||0.12J - 0.40J||1.6||0.36 J||2.8||300||RMEG|
|Cadmium||ND - 1.9 J||117 J||1.2||56.0||40||EMEG|
|Chromium||8.7J - 18.8 J||41.6 J||18.9 J||33.2||300||RMEG|
|Cobalt||ND||5.0 J||ND||5.7 J||NONE||NONE|
|Copper||8.6 - 22.3 J||605||20.3 J||351||NONE||NONE|
|Lead||5.0J - 28.2J||5,850||177 J||11,200||NONE||NONE|
|Nickel||12.3 - 26.4||738||25.4||131||1,000||RMEG|
|Silver||ND - 0.36 J||41.4||2.2||63.7||300||RMEG|
|Thallium||ND||528||0.24 J||1.3 J||NONE||NONE|
|Vanadium||ND||143 J||ND||311 J||NONE||NONE|
|Zinc||36.1 J - 103||80,100||461 J||15,900||20,000||RMEG|
|ND - not detected; J - estimated value|
|CONCENTRATIONRANGE (ug/m3)||Comparison Value|
|Antimony||ND - 0.000397J||0.0010J - 0.199||NONE||NONE|
|Arsenic||ND(0.003)||ND - 3.82||0.0002||CREG|
|Barium||0.0018J - 0.0031J||0.0022J - 0.0409J||NONE||NONE|
|Cadmium||ND - 0.0015J||0.00073J - 0.0641||0.0006||CREG|
|Cobalt||ND(0.015)||0.00029J - 0.0022J||NONE||NONE|
|Copper||0.006J - 0.0078||0.0098 - 0.20||NONE||NONE|
|Lead||ND(0.0017)||ND - 2.19J||NONE||NONE|
|Manganese||0.006 - 0.0113||ND - 1.66||0.3||EMEG|
|Silver||ND(0.003)||0.00025J - 0.0276||NONE||NONE|
|Thallium||ND(0.003)||0.000056J - 0.00312||NONE||NONE|
|Zinc||0.0088J - 0.0241J||0.025J - 12.1J||NONE||NONE|
|N/A - not analyzed; ND - not detected; J - estimated value|
Quality assurance/quality control summary data was obtained from EPA. These reports werereviewed to determine the quality of the field and laboratory data.
Access to the old mill and concentrator foundation ruins, a large pile of waste rock, and old mining equipment is not restricted. These structures may pose a physical hazard to children who might play around these areas.
ATSDR evaluated exposure pathways that might result from human exposure to contaminants inthe environment associated with the site. ATSDR considers a human exposure pathway toconsist of five components: 1) a source of contamination, 2) an environmental medium in whichexposure may occur (air, water, etc.), 3) a point of human exposure, 4) a route of humanexposure, and 5) a receptor population.
ATSDR classifies exposure pathways in which all five components are present and in whichexposure is likely to occur, or have occurred, as a completed pathway. If a component is missingor exposure is possible but not likely to occur, the pathway is classified as a potential pathway. Contaminants that exceeded ATSDR comparison values in completed exposure pathways areevaluated in further detail in the Public Health Implications section of the Health Assessment. Ifexposure is not likely to occur because several pathway components are not present, then thepathway is eliminated from further analysis in subsequent portions of the Health Assessment. Completed and potential exposure pathways are listed in Tables 6 and 7, respectively.
Children and adults may be exposed to contaminants in tailings by inhalation. The prevailingwind appears to be from the southwest placing most of the nearby residents downwind of thetailings piles. There are five houses located between the upper and lower tailings piles. Approximately 15 people reside in these homes. During the summer months, tailings arewindblown. Metals including arsenic, cadmium, copper, lead, mercury, silver, and zinc havebeen detected in high-volume air samples downwind of the residences. Residential dust samplesindicate that metals in the tailings are accumulating in the homes.
Antimony, arsenic, cadmium, chromium, copper, lead, manganese, mercury, silver, vanadium,and zinc were detected in residential surface soil exceeding regional background concentrationsand environmental guidelines. The highest levels of lead and arsenic in residential surface soilswere detected near a child's swing set. Young children and adults may be exposed to surface soilcontaminants by incidental ingestion, dermal contact, or inhalation when playing or working intheir yards. Adults and children may track site-related contaminants into their homes afterworking or playing in contaminated areas.
The tailings piles are unvegetated and uncapped. Tailings are being redistributed to thecommunity by wind and water erosion. Primarily, antimony, arsenic, cadmium, chromium,copper, lead, manganese, mercury, nickel, selenium, silver, vanadium, and zinc have beendetected in the mine tailings. The highest concentrations of these metals were detected at theruins of the old mine process foundation. Biking and walking paths are reportedly located on thetailings piles. This evidence indicates that children and adults may have direct contact with themine tailings. Residents could be exposed to contaminants in the mine tailings throughincidental ingestion, dermal contact, or inhalation.
|PATHWAY NAME|| |
EXPOSURE PATHWAY ELEMENTS
| POINT OF |
| ROUTE OF |
| EXPOSED |
|Ambient Air||Tailings |
|Air||Residences||Inhalation||Triumph Residents |
|Surface Soils||Tailings |
|Surface Soil||Residences||Inhalation |
|Mine Tailings||Tailings |
|Tailings||Tailings piles |
There is the potential for mine drainage to impact surface waters of the Big Wood River and theEast Fork of the Wood River. The east fork of the Wood River is used for sport fishing forrainbow trout. Fishermen may have dermal contact with the surface water while wading duringfishing. A domestic surface water intake (serves less than 10 people) is located 15 milesdownstream of the site. At the present time, surface water metal concentrations in the Big Wood River do not exceed federal water quality standards.
Contaminants from the tailings piles maybe migrating with groundwater and surface water runoffto wetlands south of the site and the river. Wetland sediment samples indicate that there areelevated concentrations of antimony, arsenic, cadmium, copper, lead, mercury, nickel, selenium,silver, and zinc in the sediments. Arsenic, lead, and zinc have been detected in sediments of theEast Fork Wood River. There is a potential for individuals to be exposed to sediments throughdermal contact or incidental ingestion. The frequency of human contact with wetland or riversediments is likely minimal.
Arsenic, lead, and zinc have been detected in Wood River sediments. The surface water metalconcentrations do not exceed federal water quality standards at this time. The East Fork WoodRiver is used for trout fishing. There is a potential for fish to uptake metals from the sedimentsin the river. However, no biota data are available at this time to evaluate this potential exposurepathway.
The town of Triumph obtains its water supply from two community wells: one located betweenthe two tailings piles and one located northeast of the upper tailings pile. One well is locatedupgradient of the tailings pile and one well is located downgradient of the tailings pile. Monitoring of the community wells in 1991 and 1992 did not indicate that concentrations ofmetals in the drinking water exceeded federal water quality standards.
|PATHWAYNAME||EXPOSURE PATHWAY ELEMENTS||TIME||SOURCE||MEDIUM|| POINT OF|
| ROUTE OF|
|Surface Water||Tailings||Surface water||Drainage ditch Big Wood River||Ingestion|
Big Wood River
|Biota||Tailings||Biota||Big Wood River||Ingestion||Recreational|
In this section, we will discuss the health effects of current and potential exposure tocontaminants of health concern at the Triumph Mine Tailings Site.
Bioavailability of Mine Tailings
Current scientific data does not allow us to predict the bioavailability of metals from the minetailings. Bioavailability is dependent on a number of factors, including the chemical (i.e. valenceand salt) and physical forms (i.e. size of the particulate) of the contaminant. For example,several investigators have compared the soil lead concentration/blood lead relationship betweenurban and mining communities. In these studies, a mining community was defined as a sitewhere the source of soil lead contamination was predominantly from mines or tailings. Therewas on the average 0.8 ug/dL change in blood lead concentrations per 1,000 mg/kg soil lead inurban residences as compared to residents of a mining community where there was 0.25 ug/dLchange in blood lead per 1,000 mg/kg soil lead. The authors propose that these differences in the soil lead concentration/blood lead relationshipmaybe attributed to a difference in bioavailability of the lead. Leaded gasoline, which is thepredominate source of lead in urban communities and industrial point sources, emit extremelysmall particles of lead, where as mine tailings release relatively large particles of lead, primarilyas fugitive dust. The smaller the particle the more easily it is absorbed by inhalation andingestion, thus increasing the total exposure. There may also be a difference in the chemicalspecies of the metal detected in the urban and mining communities accounting for this difference in bioavailability (6).
A second uncertainty in assessing the potential health risks from the mine tailings at the TriumphMine Site is the bioavailability of site contaminants that are inhaled. In mine tailings there is asubstantial fraction of the particulate matter that can be respired deeply into the lungs. Thisfraction depends on the particulate size, the smaller the particulate the more readily it is absorbedonce it enters the lung. The lower tailings pile contains a substantial amount of fine grainedmaterial. However, we do not know what portion of the inhaled dust from the mine tailings thatis retained in the lung and absorbed.
There are three potential routes of exposure by which residents could be exposed: 1) byincidental ingestion of residential soil and indoor dust via hand-to-mouth contact, 2) byinhalation of airborne dust contaminants, and 3) by dermal contact. A study was conducted todetermine the bioavailability of metals from oral ingestion of the tailings at the Triumph MineTailings Site. Swine were fed actual soil and tailings from the Triumph site to determine theportion of the metal absorbed from the gastrointestinal tract. The preliminary results of this study indicated that a portion of the metals can be absorbed. Preliminary results also indicated that arsenic was more readily absorbed than the lead (7).
Limited air data was available for review (3 days of air data collected in June 1991). Thepredominant wind direction is from the southwest which puts Triumph residents downwind ofthe tailings piles. The monitoring conducted indicates that site contaminants are being dispersedby the wind and are accumulating in the residential surface soils and in household dust. Thisexposure is not expected to occur year round since the tailings are covered by snow or wetteddown by rain for a portion of the year. In order, to evaluate the potential health effects from theinhalation exposure, it was assumed that Triumph residents would be exposed to thesecontaminants for 90 days per year.
Dermal contact with the contaminants could occur from activities such as playing or gardening inareas with contaminated surface soil or mine tailings. It is not expected that dermal contact withthe metals in the soil and mine tailings will produce adverse health effects because very little ofthe metal would be absorbed through the skin. It is more likely that health effects would beproduced from incidental ingestion of the contaminants from hand to mouth activity or viainhalation. Health effects from dermal contact with metals usually occurs when relatively highconcentrations are encountered with occupational exposures.
In this section of the public health assessment, we will discuss the short and long term effectsexpected to occur from incidental ingestion and inhalation of contaminants at the Triumph MineTailings Site. Both the potential for noncancer and cancer health effects will be discussed. Thisassessment will represent the worst case scenario of exposure by assuming 100% bioavailabilityof the metals from the tailings or soils and that individuals will be exposed to the maximumconcentration of contaminants reported in the mine tailings or soil. It was assumed that a veryyoung child (< 3 years of age that exhibits a lot of hand-to-mouth behaviors); an older child (> 4years of age) and an adult might be exposed to the contaminants in the soils and tailings. Theyoung child (< 3 years old) may consume up to 5000 mg of soil from hand-to-mouth behaviors. An older child (< 4 years of age) and an adult ingest less soil than the very young child fromcontact from the soil. The older child can consume up to 200 mg of soil and the adult canconsume up to 100 mg of soil from contact with the soil. These estimates of incidental soilingestion were used to determine the amount of exposure that residents may have with thecontaminated soils or tailings. Only metals that exceeded the environmental comparison valueswill be evaluated in this section.
Antimony was detected above environmental comparison values in the mine waste, mine tailings,road soil, residential yards, and indoor dust. Residents may come in contact with antimony fromthese sources through ingestion. If a young child consumed 5000 mg of the mine wastefoundation soil or the mine tailings, they could experience vomiting from a short durationexposure (< 14 days). An older child or adult would not experience adverse health effects from ashort term exposure to antimony in soil from any area of the site or from the tailings since theyincidentally ingest less soil.
Although no human studies were located that examined the effects of long term ingestion ofantimony, animal studies indicated that blood glucose levels decreased and cholesterol levelswere altered in rats exposed to levels of antimony found in the tailings or mine process soil. It isnot known if antimony can produce cancer in animals or humans (7). There have been noreported health effects to occur from exposure to the levels of antimony measured in the air.
Based on the maximum concentrations of arsenic reported in soil, a child (< 3 years of age)ingesting 5000 mg of the contaminated soil (the yard soil or road soil) might experience adversehealth effects. The health effects most likely to occur from ingestion of the contaminated soilinclude irritation of the digestive tract, leading to pain, vomiting, and diarrhea. Other healtheffects that might occur at this level of exposure include hematological effects (anemia andleukopenia) and changes in kidney function (elevated serum creatinine or bilirubin and mildproteinuria). Ingestion of 5000 mg of the mine waste/process foundation soil or tailings by achild could prove fatal. In nearly all cases, the most immediate effects of excessive arsenicexposure include vomiting, diarrhea, and gastrointestinal hemorrhage. Death may ensue fromfluid loss and circulatory collapse (8).
In an older child or adult, noncancer health effects are not expected to occur from ingestion ofarsenic in the soil or tailings from short term exposures (< 14 days per year). Based on themaximum arsenic concentrations reported in the road soil, yard soil, dust, and tailing, olderchildren and adults ingesting arsenic from these sources for long periods of time (> 365 days) may experience noncancer health effects such as hyperpigmentation and thickening of the skin and vomiting and diarrhea (8).
Arsenic has been shown to be a carcinogen in humans from ingestion and inhalation routes ofexposure. If we assume that a 100% of the arsenic is bioavailable from the tailings or residentialsoil, there is a greater that what is considered to be acceptable risk for development of cancerfrom ingestion of the tailings for lifetime residents of the Triumph community. The cancer risk isabove the 10-4 risk range considered as acceptable exposures to carcinogens. Oral exposure toarsenic has been linked to cancers of the liver, bladder, kidney, skin, and lung (8). Inhalationexposure to arsenic in the tailings represents a cancer risk above the level that is consideredgreater than what is considerable to be acceptable exposure to carcinogens for residentsdownwind of the tailings piles. However, no cancers have been reported in residents of Triumph.
Most ingested cadmium passes through the stomach and the intestines (only 1-6% is absorbed). Because of this low level of absorption of cadmium from the stomach and intestine, the amountof cadmium a child or adult would be exposed to from residential soil, road soil, mine tailings, ormine waste/process foundation soil from ingestion would not be expected to produce healtheffects. Studies of animals or humans that eat or drink cadmium have not found increases incancer.
The amount of cadmium that would be inhaled when the tailings or soil are windblown is notassociated with noncancer health effects. Cadmium has been classified as a probable humancarcinogen by the inhalation route. There is an insignificant risk for increased cancers frominhalation of cadmium in the windborne particulate at the reported concentrations.
Concentrations of lead have been reported as high as 4,860 mg/kg in the residential soils, 1300mg/kg in household dust, and 33,900 mg/kg in mine tailings. Young children can be exposed tolead in these media by incidental ingestion (hand-to-mouth behaviors). Young children areespecially sensitive to the biological effects of lead. Young children tend to absorb a higherpercentage of ingested lead and are more sensitive to the neurological effects of lead exposure.
Studies have shown that lead contamination in exterior dust and soil at concentrations of 500 to1,000 mg/kg can begin to influence blood lead concentrations in children residing in leadcontaminated areas. Blood lead levels may be raised above background approximately 5 ug/dLfor every 1,000 mg/kg lead above background (10). Blood lead concentrations of children inexcess of 10 ug/dL are considered by the Centers for Disease Control and Prevention andATSDR to be indicative of excess exposure to lead and have been associated with subtleneurological deficits and alterations of levels of critical enzymes (10).
The extent of lead absorption from the gut depends on several factors including the solubility of a particular salt of lead and dietary habits of an individual. Poor nutritional status can lead to enhanced absorption of metals.
Only 32% of inhaled particulate lead is absorbed by young children. Of the 32% inhaled leadapproximately 100% is absorbed into the blood stream, regardless of its chemical form. There is a concern for pregnant mothers because there is no barrier to uptake of lead by the fetus. The fetus begins to uptake lead from the twelfth gestational week until 9 months (10).
Although humans can be exposed to significant quantities of manganese in food and water, thereis rarely a reported adverse health effect. Approximately 3-5% of the manganese ingested isabsorbed from the gastrointestinal tract. It is unlikely that health effects will be produced fromingestion of manganese from the tailings or residential soil after short or long term ingestionexposure (11). The animal studies to determine the carcinogenic potential of manganese are notconclusive. Overall, the studies indicate that the potential for carcinogenic effects in humans is probably very small.
The levels of manganese reported in the air samples have not been associated with health effects. There are no studies on inhalation exposure to manganese and the production of cancer.
Several studies have indicated that zinc ingestion can produce gastrointestinal distress in humans. A child consuming 200 or 5000 mg of the tailings might experience gastrointestinal distress anddiarrhea after a short duration. Chronic ingestion (>365 days) of 200 mg of the tailings orresidential soil may produce an anemia (12).
Blood Lead and Urinary Arsenic Screening
Blood lead and urinary arsenic levels were assessed in Triumph residents by the IdahoDepartment of Health and Welfare and the South Central District Health Department three times(November 1991, July 1992, July 1993) (Table 8 and 9). Each participant was questionedregarding their length of residence in Triumph, prior residences, age of their housing, their sourceof drinking water, occupation and hobbies, and their consumption of red wine and seafood whenthey were tested.
Thirty-eight individuals were screened in the November 1991 screening (13) ranging in age from3 to 48 years of age. Subjects were divided into groups. Group I was comprised of individuals10 years of age or younger. Group II was comprised of individuals older than 10 years of age. The mean blood lead concentration for all 38 participants was 4 ug/dL (sd=2.7 ug/dL). Therange of blood lead concentrations was from less than 1 ug/dL to 15 ug/dL. All blood lead levelsfor the children were below the values that require medical intervention as recommended by theCenters for Disease Control and Prevention. The average total urinary arsenic concentration forthe 38 participants was 14 ug/L (sd=12.87 ug/L). Urinary arsenic levels ranged from less than 2ug/L to 74 ug/L. A normal urinary arsenic concentration is less that 100 ug/L and theconcentration is usually less than 30 ug/L in the absence of consumption of arsenic-containingfoods. The most informative clinical value for assessing arsenic exposure is the ratio ofspeciated arsenic to creatinine (8). This allows the value to be corrected for the kidney functionand hydration of the individual. The recommended level of concern occurs when the level ofspeciated arsenic/creatinine ratio in adult is 50 ug/g or greater. Laboratory reference valuesindicate that an individual is considered to be unexposed if their speciated arsenic to creatinineratio is less than 10 ug/g. There were no arsenic to creatinine ratios that exceeded the 50 ug/g value.
Since the first blood lead screen was conducted during the winter when contact with the sitecontaminants would likely be minimal, two subsequent rounds of sampling were conducted inJuly 1992 (14) and July 1993 (15). Twenty-five Triumph residents (9 children and 16 adults)were screened in July 1992. Blood lead levels ranged from 1 ug/dL to 19 ug/dL. No childrenwere reported to have had blood lead levels equal to or greater than 10 ug/dL. The values fortotal urinary arsenic ranged from 5 ug/L to 116 ug/L. The level of speciated arsenic/creatinineratio was again determined. Triumph residents had speciated values ranging from 2 ug/g to 50ug/g. This ratio was found to be higher in children (average 15.82 ug/g) than in adults (average8.31 ug/g). Investigators compared the sampling rounds from November 1991 to the resultsobtained in the July 1992 round. Total urinary arsenic levels sampled in July 1992 weresignificantly higher than those found in the November 1991 sampling round. A significantincrease in blood lead levels was also observed.
A group of twenty-two Triumph residents (8 children and 14 adults) were screened in July 1993for blood lead and urinary arsenic. Blood lead levels ranged from 1 ug/dL to 5 ug/dL (mean= 2.5ug/dL). No children had blood lead levels greater than 10 ug/dL. Urinary arsenic samples werecollected. Triumph residents had speciated arsenic/creatinine ratios ranging from less than 10ug/g to 14 ug/g. No resident exceeded the recommended ratio of concern of 50 ug/g. The ratiosof inorganic arsenic to creatinine are lower in this screening than those determined in the July1992 screening. The mean values for the speciated arsenic/creatinine were for children in July1992 were 15.82 ug/g and 8.31 ug/g for adults.
The rationale for the significant increase in urinary arsenic and blood lead levels may be due toseasonal variation of exposure, i.e. an increase in outdoor summer activities within thecontaminated area may have contributed to this increase in exposure. The increased winddistribution of the tailings in the summer maybe an additional contributing factor. Blood leadand urinary arsenic concentrations did not reflect the exposures expected for individuals living inan area with such elevated metal concentrations. The lower than expected blood lead and urinaryarsenic concentrations indicate that the metals in the tailings may be less bioavailable or thatresidents are practicing hygiene habits that would minimize their exposures.
|Age||November 1991 Blood Lead Results|
|1.0 +/- 1.0|
|1.0 +/- 1.4|
|0.9 +/- 1.1|
|1.0 +/- 1.9|
|2.5 +/- 1.9|
|Age||November 1991 (ug/gm)|
|0-10||6.1 +/- 5.3|
|11-20||7.0 +/- 1.0|
|3.1 +/- 1.6 (2-5)||4.5 +/- 3.3|
|21-30||2.5 +/- 3.5|
|4.0 +/- 5.6|
|31-40||4.6 +/- 3.9|
|0.9 +/- 2.02|
|3.3 +/- 4.9|
|5.6 +/- 5.9|
|1.1 +/- 2.1|
|3.3 +/- 2.6|
|6.3 +/- 5.1|
Triumph residents have expressed two primary concerns regarding the Triumph Mine TailingsSite to ATSDR representatives during past public availability sessions. These concerns areaddressed below.
1) What measures can an individual take to reduce exposure to metals in the soil?
There are several measures an individual can take to reduce exposure to lead in soil. Thesemeasures will also apply to reducing exposure to other metal contaminants in the soil. The steps are as follows:
a) Individuals should wash their hands after outdoor activities in which they may have contactwith soil. Hand washing removes dust and dirt that may be contaminated with metals. Individuals should also remove clothes such as shoes that may be contaminated with dirt beforeentering their homes and before having contact with their children.
b) Children should be discouraged from placing toys and objects in their mouths that may have been in contact with contaminated soil. Parents should teach children to avoid contact with tailings.
c) Household dust should be kept to a minimum. One method is to wet mop floors.
d) A sod or grass cover in outside areas where children might play would limit their contact with surface soil contaminants. This will keep exposure to dust and dirt at a minimum.
e) A well balanced diet will limit the amount of metal absorbed from the gastrointestinal tract. A diet high in dietary calcium, iron, and vitamin C, reduces the amount of ingested lead that may be absorbed into the body.
2) Is it necessary for residents to participate in additional rounds of biological sampling toassure that exposures are not occurring during spring and summer months when there isincreased outdoor activity and when tailings are wind blown from the tailings piles?
Since the tailings piles have not been capped or removed there is a potential for exposure to thetailings to occur during the summer months. Furthermore, there is the potential for youngchildren having contact with the tailings pile to incidentally ingest the material. Therefore, it ispossible that the extent of exposure may change. Periodic screens to determine changes inexposure patterns are recommended.