PUBLIC HEALTH ASSESSMENT
SALIDA, CHAFFEE COUNTY, COLORADO
In conducting a public health assessment, ATSDR health assessors identify and review all available environmental data related to contamination at the site. The on- and off-site portions of this section describe sampling that has been done and identify contaminants of concern. The quality of the environmental data is discussed in the Quality Assurance and Quality Control subsection. Physical and other hazards not related to toxic substances, if any, are described in the Physical and Other Hazards subsection. The following paragraphs discuss selecting contaminants of concern.
ATSDR evaluates the contaminants in subsequent sections of this public health assessment to determine whether exposure to them has public health significance. ATSDR selects and discusses contaminants of concern using the following information:
- concentrations of contaminants on and off the site;
- quality of field data, laboratory data, and sample design;
- comparison of on- and off-site concentrations with comparison values for noncarcinogenic and carcinogenic endpoints; and
- community health concerns.
The listing of a contaminant in the contaminants-of-concern tables (appendix 2) does not mean that it will cause adverse health effects if people are exposed at the specified concentrations. Rather, the listing of a contaminant indicates which contaminants will be discussed further in this public health assessment. The potential for adverse health effects resulting from exposure to the contaminants of health concern is discussed in the Public Health Implications section of this document.
ATSDR uses comparison values contaminant concentrations in specific media considered protective of public health to select contaminants for further evaluation. ATSDR and other agencies have developed the comparison values to provide guidelines for estimating contaminant concentrations in media that are not likely to cause adverse health effects, given a standard daily ingestion rate and standard body weight.
The comparison values include environmental media evaluation guides (EMEGs), cancer risk evaluation guides (CREGs), and reference dose media evaluation guides (RMEGs). EMEGs are media-specific comparison values used to select contaminants of concern for health effects other than cancer. CREGs are estimated contaminant concentrations expected to cause no more than one excess cancer in a million persons exposed over a lifetime (70 years). EPA's reference dose (RfD) and reference concentration (RfC) are estimates of the daily exposure to a contaminant unlikely to cause adverse health effects. RMEGs are comparison values based on the RfD. Maximum contaminant levels (MCLs) are limits on chemical concentrations in drinking water that EPA considers protective of public health (considering the availability and cost-effectiveness of water treatment technology) over a lifetime (70 years) at an exposure rate of 2 liters of water per day (for an adult). Maximum contaminant level goals (MCLGs) are EPA drinking water health goals set at levels at which no known or anticipated adverse health effects would be experienced by exposed persons. MCLs are EPA regulations that can be enforced; MCLGs are goals that are not enforceable. EPA also has lifetime health advisories (LTHAs) for drinking water. If ATSDR or EPA comparison values are not available, ATSDR may refer to other agencies' standards as applicable.
Soil and soil/sludge mix samples on-site were taken at a number of areas, including the tie-treating area, smelter area, sludge material pile area, and various drum storage areas. The tie-treating area, operated by Koppers, Inc, is now occupied by Butala Construction. The smelter was located in areas that are currently occupied primarily by Butala Construction and E & R Trucking. The sludge material pile area was located at the CoZinCo zinc sulfate fertilizer plant (12). Contaminants selected for further evaluation are presented in tables 1 through 3, appendix 2.
Maximum concentrations of arsenic (4600 ppm), barium (820 ppm), beryllium (1.1 ppm), and silver (150 ppm) were found at on-site soil sampling locations (13, 14) (table 1). Other metals exceeding ATSDR comparison values were also found in soil (table 1). Several thousand ppm arsenic and lead were detected in several soil samples near the smelter area. Some of this area has been covered with gravel as a temporary measure to prevent exposure. Additionally, there are plans to complete fencing of E & R Trucking by Fall 1994. Contamination in the area of the smoke stack (historical monument) has exposure implications particularly because it is visited by residents and tourists.
Final soil sampling (shallow subsurface samples) of the Limed Sludge Material Pile area on the CoZinCo subsite occurred in July 1992. The data indicate that soil was well below clean-up criteria (9). Total cadmium concentrations were less than 10 ppm and total lead concentrations were less than 70 ppm (12). The contaminants listed in Table 3 are metals concentrations prior to the excavation and removal of contaminated materials. Metals exceeding ATSDR comparison values were antimony (627 ppm), arsenic (106 ppm), barium (399 ppm), cadmium (199 ppm), chromium (635 ppm), lead (78,900 ppm), nickel (1120 ppm), vanadium (35 ppm), zinc (214,000 ppm), and possibly selenium (6.5 ppm) (table 3). The concentration for selenium is an estimate which is not significantly different from the comparison value of 4 ppm (table 3). The Limed Sludge Material Pile was excavated and removed from the site by August 1992.
In the tie-treating area there were a number of organic contaminants, as would be expected (table 2). These chemicals were largely polynuclear aromatic hydrocarbons (PAHs) and creosote compounds commonly associated with creosote compounds used in treating railroad ties. Primary areas of organic contamination are the former site of Koppers process building and northeastern lagoons. Additionally, there is the source area of migrating creosote in a spring. In 1992 and June 1993, many areas visually contaminated with creosote-stained soil were removed from Kopper's (9, 15). Some burial areas and other sources containing creosote remain on site (9). The source of migrating creosote in the spring has yet to be determined. There were several species of chlorinated dioxins and furans identified in on-site soils (none were tetrachlorinated species).
In 1987, an on-site slag pile was sampled for organic and inorganic contaminants (16). Slag is a waste product generated when ore is heated to high temperatures. As would be expected in such a process, if there were organic materials in the ore, they would be volatilized at the high processing temperature and liberated. Consequently, it would be unlikely that there would be significant organic contamination in waste slag. The 1987 data confirm this observation. Although there were several organic species identified in the slag, they were at very low levels.
Inorganic constituents at levels above comparison values in smelter slag and smelter slag precipitate include: arsenic (500 ppm), barium (2000 ppm), cadmium (21 ppm), chromium (21 ppm), manganese (29,989 ppm), silver (32 ppm), antimony (54.6 ppm), beryllium (3 ppm), lead (14,000 ppm), nickel (52 ppm), vanadium (110 ppm) and zinc (41,000 ppm) (table 4).
Leaching tests conducted on smelter slag and smelter slag precipitate indicate limited leachability of metals (9). The abundance of slag pile precipitates indicates on-going leaching and migration of the slag pile (9). The slag pile is located less than 400 feet from the Arkansas River.
Past on-site pond sediments (East and West Ponds on CoZinCo) contained organic and inorganic contamination; however, the organic contaminants were at very low concentrations, and are not believed to be at levels of health concern. Heavy metals exceeding ATSDR comparison values (table 5) included: arsenic (129 ppm), barium (251 ppm), cadmium (82 ppm), chromium (335 ppm), lead (89,400), manganese (786 ppm), antimony (731 ppm), nickel (428 ppm), vanadium (29 ppm) and perhaps selenium (5.3 ppm). Remediation has taken place for the East and West Ponds.
There is one known spring on-site contaminated with creosote. Sediment near this spring contains PAHs (Table 6). PAHs which have comparison values and are exceeded for an ingestion scenario include: fluorene (1300 ppm), anthracene (1500 ppm), pyrene (2500 ppm), fluoranthene (2400 ppm), and benzo(a)pyrene.
On-site groundwater contained a number of metals at levels above comparison values (table 7). They included: antimony (0.20 ppm), arsenic (0.024 ppm), cadmium (0.018 ppm), lead (1.5 ppm), manganese (2.2 ppm), nickel (0.16 ppm), zinc (98.9 ppm), and mercury (0.0002 ppm). The metals were detected in on-site groundwater at Koppers Inc. and CoZinCo. Although sulfate and nitrate were found in on-site groundwater, their concentrations are not at levels of concern for drinking water consumption. Mercury was found in the reference spring, upgradient of the site, and an upgradient monitoring well, indicating a source other than SMT.
There were also some organic contaminants in on site ground water, primarily PAHs (table 8). These contaminants were found in on-site monitoring wells and in sludge spring 1, not drinking water wells. Specific PAHs exceeding comparison values include pyrene, fluoranthene, benzo(a)anthracene, chrysene, and benzo(a)pyrene (table 8). Concentrations exceeding comparison values were found only in Sludge Spring 1 which had a creosote compound total of 6.73 ppm. Sludge Spring 1, on Koppers Inc., seeps into the Arkansas River and is upstream of the Shavano State Fish Hatchery (4). The extent of PAH contamination in groundwater has not been determined.
Limited air sampling was carried out on-site in November 1987 (16). The sampling occurred at four stations over two days time; meteorological data were collected during the sampling. Although there were a number of organic and inorganic air contaminants identified, they were at low levels (table 9). This sampling event did not include sampling for acid mists or other sulfur compounds which were the subject of community concern in September 1992.
In March, 1989, CoZinCo had stack testing performed on their process emissions to see if they were in compliance with state air requirements (17). These tests measured particulate, sulfate, and metals mass emission rates. The results of these were not expressed in ambient air concentration terms; consequently, ATSDR could not directly examine these data with respect to comparison values. Table 10A shows the emission rates of the metals from the CoZinCo stack. Enough data were available for ATSDR to run a screening model, TSCREEN, to develop reasonable estimates of the maximum ground level concentrations at about 125 meters (a meter is approximately a yard) away for each of the metals emitted (18)(table 10). Based on this examination, nickel appeared to be at levels that would exceed the comparison values used to select contaminants for further evaluation. The air testing contractor suggested that the "trace" of nickel found may have originated from the stainless steel stack sampling probe (17).
CoZinCo has permanently discontinued use of their canal dissolver, which was a significant source of acid mists, as of November 1992 (19, 20). They have added scrubbers to reduce air pollution from emissions. They have also replaced outdoor uncovered stockpiles of sludge materials with closed containers (20).
In September, 1993, CoZinCo performed stack testing on their process emissions (mixer scrubber and vat scrubber outlets). The tests measured particulate, sulfuric acid, hydrogen sulfide, and metals emissions (21). The Colorado DPHE, Air Pollution Control Division, is currently reviewing the CoZinCo air pollution emissions permit. According to the Division, CoZinCo is in compliance with their draft permit and has minimal emissions (19). However, no risk assessment of air emissions was done. ATSDR's analyses of the 1993 emissions data, using TSCREEN, is shown in Table 10B. This table shows estimated concentrations at 80 meters based on mixer scrubber emissions. For each metal listed (cadmium, chromium, lead, and nickel), a comparison value is exceeded or approached. The vat scrubber would contribute additional emissions which are not represented by this table. There are also ambient air background concentrations of metals. The analyses indicate that metal emissions should be evaluated further, including an evaluation for long-term chronic effects. ATSDR has recommended that a risk assessment for metals emissions be completed.
On-Site Contamination Summary
The sampling of on-site soils, sludges, slags, and groundwater clearly indicate contamination with various metals. There was also some organic contamination, mostly PAHs, in the area of the past tie-treating operations at the Koppers plant. Much of the sampling took place in 1986 through 1988, before a number of specific site source cleanup actions. The sludges have been removed from the site as well as loads of creosote contaminated soils. Remedies for the slag pile and groundwater have yet to be determined. Air emission issues at the CoZinCo facility are being addressed by CoZinCo in coordination with the Colorado Air Pollution Control Division.
The environmental data described in the following sections were designated as off-site by ATSDR. Samples designated as off-site tend to be located away from active present industrial operations, and usually are located at or near a residence. Since most removal activities have been done at off-site locations and residents provided with bottled water, the results of the analyses may reasonably approximate past exposures. However, off-site soils may not yet be fully characterized with respect to historical air-borne deposition (see recommendation 5).
Maximum values of selected inorganic contaminants in residential soil include: antimony (14 ppm), arsenic (1300 ppm), barium (1190 ppm), beryllium (1.4 ppm), cadmium (290 ppm), chromium (66 ppm), lead (16,000 ppm), manganese (670 ppm), silver (14 ppm), vanadium (42 ppm), and zinc (8,000 ppm) (table 11). These levels were found in soil before removal activities at homes. Contaminated soil was removed by October 1993. After removal activities, residential soil contained maximums of 220 ppm cadmium, 710 ppm lead, and 2400 ppm zinc. Arsenic was below the detection limit of 110 ppm. This soil was covered with 6-8 inches of clean fill (9).
Four areas on residential property were found to contain creosote contamination in soils (9). This contamination was removed in September 1993. Maximum concentrations of PAHs and other organic compounds are listed in Table 12. One of the four areas was driveway and sidewalk surfaces at an abandoned residence.
However, most off-site soil samples contained organic contaminants at very low levels. Where comparison values exist, the measured levels of contamination were below those levels. There were a number of chlorinated species of dioxins and furans identified in soils; however, no 2,3,7,8 tetrachloro-dibenzo-p-dioxin (the species of dioxin considered to be most toxic) was found.
House dust samples were collected from several residences southwest of CoZinCo. Lead concentrations were higher in some residences and believed to be related to contaminated soil in the yards and surrounding area (9). The homes were cleaned to reduce incidental ingestion of metals in dust. Contaminated soil at these residences was removed by October 1993 and replaced with clean fill. Therefore, the suspected source of lead and other metals has been removed. Further contamination of these residences and yards is unlikely if proper dust suppression methods are used during remedial activities.
Maximum values of selected inorganic contaminants found in Arkansas River sediment samples include: cadmium (4.1 ppm), chromium (29 ppm), manganese (578 ppm), lead (267 ppm), vanadium (134 ppm), and zinc (1500 ppm) (table 13).
Springs discharging to the Arkansas River have elevated metals (near the residential areas). The potential also exists for creosote contamination to migrate to the River through springs.
Off-site surface water sampled from the Arkansas river had low levels of inorganic contamination. Only two metals, cadmium (0.012 ppm) and silver (0.081 ppm) would exceed ATSDR's comparison values if the surface water was consumed by children at levels comparable to normal drinking water consumption (table 14).
Groundwater (nondrinking water)
Maximum values of selected contaminants found in off-site monitoring wells, irrigation wells and springs include: antimony (0.22 ppm), arsenic (0.006 ppm), cadmium (0.02 ppm), chromium (0.083 ppm), lead (0.046 ppm), manganese (0.12 ppm), mercury (0.00078 ppm), nitrate (19.7 ppm), zinc (140 ppm), silicon (7.25 ppm) and sulfate (761 ppm) (table 15). Although the contaminants were selected based on drinking water standards, these concentrations were not consumed because no one drinks this water. Concentrations of contaminants found in drinking water are presented in the next section.
The maximum off-site contaminants were found in groundwater south/southwest of CoZinCo. Many of the maximum levels reported above were detected on the same residential property. These data along with area hydrogeology suggest that shallow groundwater contamination is limited to the area southwest of CoZinCo and east of the Arkansas River. Mercury was found in the reference spring, upgradient of the site, and an upgradient monitoring well, indicating a source other than SMT. Heavy metals and sulfate contamination are linked to the CoZinCo site (9).
Groundwater (drinking water)
Well water and springs used for drinking water were sampled October 1986 through February 1988, August/September 1992, and March and September 1993 (28). Residential drinking water was sampled by both EPA and the Salida homeowners group.
Wells located south/southwest of CoZinCo, in the direction of groundwater flow from CoZinCo, showed contamination as described below. Water used in the past for drinking water contained cadmium, lead, zinc, silicon, mercury and nitrate at levels exceeding health guidelines (table 16). There were four drinking water wells/springs in this locality which were used in the past. In May 1994, CoZinCo was required to supply these residents with alternate water (22). In 1993, EPA had supplied bottled water to residents (23). The residents are continuing to be supplied bottled water until a more permanent solution can be established (23). Wells east and north do not show evidence of metals contamination and are considered upgradient of shallow groundwater contamination (9). Mercury contamination is found upgradient of the site and is not considered to be site related.
An apartment well and a nearby residence, both southwest of CoZinCo, were found to be contaminated with zinc in October 1986 (14.1 and 19.2 ppm, respectively). The Lifetime Health Advisory (LTHA) for zinc is 2 ppm (table 16). Samples taken through September 1993 indicate concentrations consistently exceeding the LTHA. A maximum concentration of 34.7 ppm was detected in the residential well in March 1987 (table 16). Domestic spring water also contained zinc concentrations exceeding the LTHA in September 1986 and August 1987.
Additionally, the apartment well contained 0.094 ppm lead in February 1988 (table 16). EPA's action level for lead is 0.015 ppm. Water samples taken from September 1992 through September 1993 indicate concentrations below detection limits. Additionally, a domestic spring contained 0.0162 ppm lead in March 1993. Water samples taken in May, June, and September 1993 indicate concentrations ranging from below detection limit to 0.0024 ppm.
In September 1992, drinking water sources southwest of CoZinCo had cadmium concentrations (ranging from 0.006 to 0.009 ppm) exceeding the MCL of 0.005 ppm (table 16). However, cadmium concentrations declined thereafter and were less than the MCL.
A maximum nitrate concentration of 14.6 ppm was detected in one residential well in March 1987.
ATSDR is unaware of any deep drinking water wells near the site. EPA plans to determine if deep groundwater (i.e., water from below the highly permeable sand and gravel aquifer) has been contaminated with creosote (PAHs). However, at this time, no data exist.
There were no off-site air data available for ATSDR's review.
Area fish (trout) tissue was sampled for various contaminants in 1987, 1988, and 1993 (table 17). There were a number of organic and inorganic contaminants. ATSDR has not developed direct comparison values for fish tissue; consequently, for the fish contaminants ATSDR estimated exposure doses from ingestion exposure scenarios and compared the dose to doses which resulted in adverse health effects in people or experimental animals as described in the scientific literature. These comparisons take into account the uncertainties inherent in relying on harmful effects produced in animals to predict the possibility of effects in people, as well as differences among people. In this manner no contaminants were identified as being of health concern.
Off-Site Contamination Summary
Metals-contaminated soil has been removed from a number of residences south/southwest of CoZinCo and replaced with clean fill. A few areas containing PAHs in soil were also excavated. A limited area between CoZinCo and the Arkansas River is contaminated with metals in groundwater that have migrated from the site (9). Residents in this area are being provided with bottled water. Residences with elevated lead in house dust have been cleaned.
The conclusions in this public health assessment are based largely upon data provided by various governmental and private investigations of environmental conditions associated with the subject site. Generally, ATSDR did not have access to detailed descriptions of QA/QC procedures used for each data set; however, there were indications that generally accepted QA/QC procedures were observed. Consequently, all data provided to ATSDR were analyzed and regarded as valid unless otherwise noted in the original data set.
A number of physical hazards are present on site because of the chemical processing and rock-crushing activities. Motorized equipment and movement of heavy equipment, storage tanks, chemicals and concentrated acid, fire and explosion hazard, ponds, and abandoned buildings constitute the types of hazards that can be encountered on site. No unanticipated physical hazards, other than those typical to an active industrial setting, are present at the site. Much of the Smeltertown site is readily accessible to the public.
Toxic Chemical Release Inventory
ATSDR conducted a search of the EPA Toxic Chemical Release Inventory (TRI) for Salida and Chaffee County for 1987, 1988, 1989, and 1990. For any of 300-plus toxic chemicals, EPA requires that the manufacturing industry report annual estimated releases into the environment. CoZinCo was the only facility identified through this search. In each of the reporting years, CoZinCo reported air releases of zinc compounds and sulfuric acid.
Although there were no other reported sources of chemical releases to the air or other media in the county, it should be noted that there may be other facilities that did not report because they were too small to be required to report, or they simply were not aware that they were required to report for the TRI database. It should also be noted that the TRI system does not reflect any environmental releases prior to 1987, the year that the reporting system was instituted.
An environmental exposure pathway is the means through which an individual is exposed to contaminants from a source of contamination. The elements of an exposure pathway may have occurred in the past, may be occurring in the present, or may occur in the future. In addition, an exposure pathway may be categorized as either a completed or potential exposure pathway.
An exposure pathway exists if the following five elements are present.
1. Source of contamination. Either the source of contamination, or the environmental media containing the contamination, must be present at a point of human exposure. Typical sources include landfills, industrial ponds, waste disposal areas, and emission stacks.
2. Environmental media and transport mechanisms. Environmental media that may be contaminated include groundwater, surface water, surface soils, subsurface soils, sediment, air, biota, or waste materials. A transport mechanism must also exist to move contaminants from either the source or contaminated media to points of potential human exposure.
3. Point of exposure. Typical examples of points of either potential or actual human contact with a contaminant or contaminated medium include wells, springs, yards, playgrounds, homes, work sites, the food-chain, or bodies of water.
4. Route of exposure. This is the means by which a contaminant actually enters or contacts the body, such as ingestion (eating, drinking), inhalation, skin contact (followed by ingestion), and skin absorption.
5. Receptor population. These are persons who are exposed or potentially exposed to a contaminant at a point of exposure. ATSDR regards people who come in contact with contamination as exposed; for example, people who drink water known to be contaminated, or who reside in an area with contaminated air, or who work or play in contaminated soil are considered exposed.
An environmental exposure pathway is completed when all five elements are present; and, past, present, or future human exposure is either found or predicted. Completed exposure pathways are summarized in table 18.
Ambient On-site Air pathway
Air characterization data for the Smeltertown site are limited to on-site air data from the CoZinCo subsite. There were low levels of organic and inorganic contaminants measured in on-site air (16). All five elements of an exposure pathway are present; consequently, this is a completed pathway. Available data indicate current conditions but do not fully and adequately describe past air conditions. This pathway should be evaluated further as the data become available.
Both on- and off-site soils have shown contamination. Most of the site is easily accessible and provides opportunity for human exposure. For young children living or who have lived in the immediate Smeltertown area, residential surface soil exposure through ingestion could be important. Local residents and tourists visit the smokestack area which has high concentrations of some metals. Workers and trespassers, including children, are exposed to on-site soil via ingestion. Adults and older children ingest approximately 100 mg per day. If there are local children having pica behavior (the tendency to eat non-food materials), they might ingest up to 5,000 mg per day. Additionally, off-site soils may not yet be fully characterized with respect to historical air-borne deposition (see recommendation 5).
Contaminated soil is believed to have contributed to metals in house dust. Children with the habit of putting objects in their mouths and playing on floors were probably exposed to metals in house dust. In October 1993, the CDPHE performed blood lead surveillance of Colorado children. No children from Chaffee county, including communities near the SMT site, have been reported with a blood lead level at or above 10 ug/dl.
Hydrogeology near the Smeltertown site indicates that shallow groundwater flows southwest toward the Arkansas River. The site is located in alluvium (sand and gravel deposits) which has high permeability. In general, groundwater contributes to the stream-flow of the Arkansas River as evidenced by springs along the river banks. The hydrogeology suggests the Arkansas River downstream of the Smeltertown site receives groundwater coming from the site.
The residential well and spring sampling results show metals contamination in groundwater southwest of CoZinCo but not east or north. Water soluble metals can be and apparently have been transported by groundwater in the area. Groundwater users downgradient or south/southwest of CoZinCo have been exposed to heavy metals. Water from springs and shallow wells is used by some residents of Smeltertown for cooking and bathing. Residents whose wells have been contaminated are using bottled water for drinking water. Since no deep groundwater well users are known and deep groundwater has not been characterized, this potential exposure pathway will need to be evaluated as information becomes available.
There do not seem to be any present indications that the municipal water supplies for Salida or Poncha Springs are being impacted from the Smeltertown site. Based upon limited information available to ATSDR (site visit, 10), the local hydraulic gradients, and hydrogeologic features would seem to preclude contamination of any of these public water sources by groundwater underlying this site. This lack of impact on municipal water supplies was previously addressed under Natural Resources.
A potential exposure pathway exists when one or more of the five pathway elements are missing, but past, present, or future exposure is possible due to the characteristics of the site and the surrounding area. Potential exposure pathways are summarized in table 19.
Ambient Air Pathway
There are no current air characterization data available for off-site ambient air. Similarly, there are no data available for past characterization of either on or off-site air. However, given the location of past and present industrial activities at Smeltertown, it is likely that residents in the area are and have been exposed to process air emissions. Also, there are on-going activities at CoZinCo that result in air emissions that have not been completely characterized. Air emission issues are currently being addressed by CoZinCo (24, 25). In the absence of characterization data, it is not possible to evaluate the health significance of this exposure pathway.
Site-related contaminants have been detected in both on- and off-site sediments. Children playing in or near the local springs or the Arkansas river could be exposed to contaminated sediments through skin contact and ingestion. However, although the frequency and duration of such exposures is difficult to evaluate, the exposures are probably at levels below health concern.
Area fish have shown contamination with organic and inorganic chemicals. Data were not extensive enough to tell if the contaminants were strictly related to the Smeltertown site or possibly from other sources. However, assuming standard fish consumption rates, it appears that this potential exposure pathway is not of health concern.
Surface Water Pathway
Surface water could constitute a significant exposure pathway if used as a potable water source; however, because ground water is widely available as potable water, this is considered unlikely. The water does not pose a health concern for skin contact.
In this section, ATSDR discusses health effects of chemicals that people were exposed to on the site, evaluates available health outcome data, and addresses specific community health concerns.
To determine whether people can get sick from exposure, ATSDR begins by estimating daily exposure doses for each contaminant of concern by each route of exposure. We use information about levels of contaminants and about people's activities to estimate the exposure dose. To estimate exposure doses, we use the maximum level found for each contaminant. In this way, we evaluate the worst-case scenario. The estimated exposure dose is then compared to a Minimal Risk Level (MRL), which is an estimate of daily exposure to a contaminant below which non-cancer disease is unlikely to occur. To develop the MRL, ATSDR relies on information from scientific studies of the effects of exposure to contaminants on people and animals. If an exposure dose exceeds an MRL, or if no MRL has been developed, the estimated exposure dose is then compared to other health-based guidelines such as the EPA's reference dose, or to doses which resulted in adverse health effects in people or experimental animals as described in the scientific literature. These comparisons take into account the uncertainties inherent in relying on harmful effects produced in animals to predict the possibility of effects in people, as well as differences among people.
To determine whether exposure at this site may cause cancer, a numerical increase in the risk of cancer is estimated using the estimated exposure dose and a cancer slope factor developed by the EPA specifically for each cancer-causing chemical.
For purposes of this public health assessment, ATSDR staff evaluated the toxicological implications of exposure to soil and groundwater contamination on and off the site. ATSDR staff assumed that trespassers on the site, both adults and children, would come into contact with site contaminants less frequently than would workers. For this reason, ATSDR staff have estimated exposure doses for workers who may have gone into the most heavily contaminated areas on site every working day and incidentally ingested (that is, swallowing by accident, as a result of other swallowing activities) soil contaminated at maximum levels.
ATSDR staff have also estimated exposure doses for adults, children and pica children who may have been exposed to residential soil off the site. These exposure doses are based on the assumption that individuals went into the most heavily contaminated part of their yard every day, all year. Children ingest small amounts of soil (up to 200 milligrams [mg] per day) in the process of playing; some children exhibit pica behavior, that is, they eat non-food materials, and these children may ingest 5,000 mg soil or more in a day. ATSDR staff estimated exposure doses for adults and children who drank contaminated groundwater. Because much of the contaminated soil, both on and off the site, has been removed, estimated soil ingestion doses refer to past exposures. In areas where remediation has not occurred, specifically near the smelter stack, current estimated doses may remain the same as past estimated doses. Because residents southwest of CoZinCo, in the area of groundwater contamination by metals, are being provided with alternate water, all estimated water ingestion doses refer to past exposures.
Some adults working on site are estimated to have ingested doses of lead and arsenic that may result in adverse health effects; exposure to other contaminants on site are not expected to have resulted in adverse health effects. High levels of arsenic presently remain on the site.
Some adults working in the tie-treating area are estimated to have ingested doses of PAHs that may have resulted in adverse health effects. Maximum levels of PAHs, pentachlorophenol (PCP), creosote compounds, chlorinated dioxins and furans were found in the old tie-treating area.
Adults, children and pica children who live in residences where the soil is contaminated at maximum levels are estimated to have ingested doses of lead and arsenic at levels of health concern. In addition, pica children are estimated to have ingested doses of manganese and zinc at levels of health concern. As these conclusions are based on soil contamination levels before soil removal actions, the exposures are past public health concerns. Digging and gardening activities on cleaned up properties, however, may cause exposure presently and in the future.
Adults and children who drank from wells contaminated with maximum levels of lead and zinc may have ingested doses of those chemicals at levels of health concern. Ingested zinc from soil would add to the zinc exposure dose. As this conclusion is based on drinking water contamination levels before alternate drinking water was provided, it represents a past public health concern.
Below you will find a brief discussion about potential health effects of exposure to the chemicals arsenic, creosote, lead, manganese, polychlorinated biphenyls, polynuclear aromatic hydrocarbons, and zinc.
Adults who worked in the E&R trucking area may have been exposed to arsenic at levels of health concern; workers do not currently work in this area. In addition, because the smelter stack is included in the area, it is possible that elementary school-aged children play there occasionally. If children were to play in the most heavily contaminated area at E&R trucking twice a week, or even once ingesting more than 200 mg of soil, those children would be exposed at a level of health concern. Also, adults, children, and pica children who lived at a residence heavily contaminated with arsenic may have been exposed at levels of health concern. Children and pica children who live at other residences may have been exposed at levels of health concern, although adults who live at those residences probably were not at risk of health effects due to arsenic in soil. As these conclusions are based on soil contamination levels before soil removal actions, they represent past public health concerns. Digging and gardening activities on cleaned up properties, however, may cause arsenic exposure presently and in the future.
ATSDR staff have identified studies of people who ingested doses of arsenic similar to those that children described above might receive. All studies mentioned here are referenced from the ATSDR Toxicological Profile for arsenic (26). Characteristic effects of arsenic ingestion include a pattern of skin color changes on the face, neck and back, and the formation of warts and corns on the hands and feet. Studies indicate that after prolonged exposure, these warts may develop into skin cancer. There is evidence from a large number of human studies that arsenic ingestion increases the risk of developing skin cancer.Other studies indicate that people who ingested arsenic for years have experienced circulatory problems. Some people who ingested doses only slightly above the maximum dose that a child who lived at a residence maximally contaminated might have received had blood problems (anemia and leukopenia) after a short time. People who ingested doses about ten times larger than the maximum dose estimated for this site experienced serious neurological problems after a short time; people who ingested levels of arsenic somewhat less than the maximum estimated dose but for a longer time (over at least 6 months) also experienced neurological effects, such as numb hands and feet or "pins and needles."
Although ATSDR staff have no indication that children play in the area, if a small child plays several times a week, or even once and ingests at least 200 mg of soil from the E&R trucking area most heavily contaminated with arsenic, that dose of arsenic could cause serious health effects. Various studies in humans and animals exposed one time to a dose similar to that a small pica child would receive in the most heavily contaminated areas showed developmental, neurological, renal, gastrointestinal or other effects. Other studies indicate that people who ingest ten to one hundred times more than what a pica child might ingest in the area most heavily contaminated have died.
Creosote, a widely used wood preservative, is composed of a complex mixture of many chemicals. About 300 chemicals have been identified in creosote, and there may be 10,000 other chemicals present in the mixture. The major chemicals that can cause harmful health effects are polynuclear aromatic hydrocarbons (PAHs), phenol and cresols. ATSDR staff have information about PAH levels at the site, and have evaluated the toxicologic implications of exposure to PAHs below. Maximum phenol levels found are below levels of health concern. ATSDR is not aware of any data specific to cresol levels.
Studies of rats and mice experimentally exposed to creosote mixtures indicate that harmful health effects would not be expected at doses workers are estimated to receive at the site (27). However, no studies examining the direct association between cancer and ingestion of creosote were located. Studies of PAHs, a component of creosote, indicate that PAHs may cause cancer. The toxicologic implications of exposure to PAHs at this site are discussed below.
Workers and nearby residents may have been exposed to lead via ingestion of contaminated soil, house dust, and drinking water. Digging and gardening activities on cleaned up properties, however, may cause lead exposure presently and in the future.
In October 1993, the CDPHE performed blood lead surveillance of Colorado children. No children from Chaffee county, including communities near the SMT site, have been reported with a blood lead level at or above 10 ug/dl.
Most lead studies discuss adverse health effects in terms of blood lead level rather than external exposure level. In addition, occupational studies consider exposures to be multi-route (simultaneous ingestion, inhalation, and dermal exposures). Therefore, the effects of lead on human health will be discussed here in terms of exposure by multiple routes rather than by ingestion only.
Using recent scientific information and studies, the Centers for Disease Control recently re-evaluated its guidelines on acceptable blood lead levels. New data indicate that significant adverse health effects can occur in children with blood lead levels previously believed to be safe. Some health effects have been documented at blood lead levels as low as 10 micrograms lead per deciliter blood (µg/dL) (28).
Blood lead concentrations of 10 µg/dL are associated with neurobehavioral deficits, hearing impairments, and inhibition of hemoglobin synthesis in children (29). Blood lead levels of 10-20 µg/dL in children have been shown to result in a 4- to 5-point decrease in Intelligence Quotient (I.Q.), and in electrophysiologic changes in brain activity. Blood lead concentrations greater than 33 µg/dL in children produce neurotoxic effects as well as a depression in plasma levels of Vitamin D. Neurotoxic effects of lead in children are of great concern because they may be irreversible, even after blood lead levels return to a normal range (29).
Occupational and general population studies indicate that exposure to low levels of lead in middle-aged men is associated with hypertension (29). Additionally, studies indicate small but significant direct associations between blood lead levels and blood pressure. Exposure to high levels of lead may cause adverse reproductive effects, particularly miscarriages and still births, in women and decreased sperm count and sperm motility in men (29).
Pica children who lived near the site may have been exposed to manganese at levels of health concern. As this conclusion is based on soil contamination levels before soil removal actions, it represents a past public health concern. Children and adults are not at risk of health effects due to exposure to manganese in soil at present or past levels.
Manganese is a naturally occurring element and can be found in our air, water and food. Eating a small amount of manganese each day is important in maintaining good health; too much manganese, however, can cause illness. Studies in neonatal (baby) rats indicate that exposure to manganese at levels about ten to one hundred times what a pica child might ingest from soil near the site can cause neurological damage. The studies also indicate that baby rats are more susceptible to neurological damage associated with exposure to manganese than are adult rats (30). The estimated dose a pica child would have received from residential soil is at the upper end of the provisional recommended range for safe and adequate daily manganese intake for infants (31). In the absence of other sources of ingested manganese, the dose a pica child would have received is probably not of concern. However, as there are multiple sources of manganese, pica children should avoid eating soil contaminated with manganese.
Polychlorinated Biphenyls (PCBs)
Animal studies indicate that PCBs are a probable human carcinogen. ATSDR staff estimated that workers exposed to maximum levels of PCBs at E&R Trucking are at no increased cancer risk (32).
Polynuclear Aromatic Hydrocarbons
All studies mentioned here are referenced from the ATSDR Toxicological Profile for polycyclic (which is the same as polynuclear) aromatic hydrocarbons (33). Polynuclear aromatic hydrocarbons (PAHs) are a group of chemicals that are formed during the incomplete burning and/or heating of coal, oil, gas, garbage, or other substances. Animal studies indicate that oral exposure to some PAHs are carcinogenic. Although no studies were located regarding cancer in humans following exposure to PAHs, carcinogenic PAHs are classified by the EPA as Probable Human Carcinogens based on animal studies. Carcinogenic PAHs at this site include benzo(a)pyrene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, and chrysene. The EPA has developed a methodology by which carcinogenic PAHs may be added together to determine a toxicity equivalence. The methodology is based on each carcinogenic PAH's relative potency to the potency of benzo(a)pyrene.
Workers who worked in the tie-treating area on a daily basis for at least ten years or who worked less frequently but for a longer time may have a moderately increased risk of developing cancer, particularly of the liver, mammary gland and respiratory and gastrointestinal tracts, over a lifetime from exposure to PAHs in soil.
Studies with rats indicate that inhalation of a combination of benzo(a)pyrene and sulfur dioxide (SO2) lead to an increase in lung cancer as compared to inhalation of benzo(a)pyrene alone. SO2 by itself is not carcinogenic. Although the levels of PAHs in the air may not be of health concern, they may be increasingly of concern when coupled with sulfur dioxide emissions.
ATSDR staff examined levels of exposure to individual PAHs in animal studies and concluded that non-carcinogenic health effects related to exposure to PAHs are not likely to occur in people near this site.
People who drank from wells contaminated at maximum levels may have been exposed to zinc at levels of health concern. These people could have increased their zinc dose by incidental soil ingestion. As this conclusion is based on contamination levels in water no longer used for drinking purposes, it may represent strictly a past public health concern.
Zinc is a naturally occurring element and can be found in our air, water and food. Eating a small amount of zinc is important in maintaining good health; too much zinc, however, can cause illness. Studies have been conducted in people who were exposed to zinc for several week at levels similar to those to which people drinking contaminated water are estimated to have been exposed (34). People in these studies had changes in their blood (decreased serum HDL), some experienced abdominal cramping and vomiting, and some had damage to their immune systems.
The majority of community health concerns focus on symptoms typically associated with exposure to air pollutants. The databases maintained by the State (cancer registry, birth defects registry, mortality records) do not provide any relevant insight with respect to the health outcomes of concern to the community. Consequently, these databases have not been examined with respect to this site. However, the community health concerns are evaluated with respect to the known site-related contamination for plausibility of being associated with particular health effects. This discussion is presented in the next section.
Community members raised several health concerns. Since industrial companies continue to operate on the site, potential health effects will be separated into two categories for discussion. The first category is health effects that may be related to long term or past exposure to contaminants of concern, particularly in soil and drinking water.
- Skin cancer may result from ingestion of arsenic, a soil contaminant at this site. Estimated
exposure levels for workers and residents associated with this site for many years indicate a low
increased risk of developing cancer over a lifetime. However, skin cancer is a relatively common
cancer in the United States. In addition, solar radiation is the chief cause of skin cancer, and may
be responsible for about 90 percent of all cases (35). Location, altitude and sky cover all
influence the degree of effect the sun has on the development of skin cancer; Smeltertown's
relatively high altitude and open skies make it a location where residents are at a greater risk of
developing skin cancer than much of the United States. Finally, ATSDR staff cannot determine
whether the cause of skin cancer in an individual associated with the site would be related to
arsenic, radiation, or other causes.
Birth Defects and Learning Disabilities:
- Birth defects and learning disabilities have been associated with exposure to lead. Without more
information about the types of birth defects and learning disabilities, ATSDR staff cannot evaluate
the relevance of exposure to site-related contaminants toward the development of these serious
problems. Currently there is no evidence indicating elevated blood lead levels in children. Even
with more detailed information, it would be very difficult to establish a link between exposures to
site-related contaminants and the development of adverse health effects.
Vegetables Grown in Home Gardens:
- No analysis of contaminant levels in vegetables was conducted. ATSDR staff have estimated
contaminant levels in plants grown on the most heavily contaminated residential soil; the estimate
indicates that vegetables, especially leafy vegetables such as lettuce and spinach, may take up
metals such as lead and cadmium at a level of health concern. Metal-contaminated soil has been
removed from residential areas and replaced with 6-8 inches of clean fill. This protection may not
be adequate as roots often extend below 6 inches. People who grow vegetables on remediated
residential property should consider having their vegetables tested. Eighteen inches of clean fill is
recommended for gardening in previously contaminated areas.
Drinking Water Safety:
- Residents who use groundwater from springs and shallow wells should be aware that
groundwater data indicate a health concern for groundwater users southwest of CoZinCo but not
for users to the north, east, or southeast of CoZinCo. There do not seem to be any present
indications that the municipal water supplies for Salida or Poncha Springs are being impacted
from the Smeltertown site. Based upon limited information available to ATSDR (site visit, 9), the
local hydraulic gradients, and hydrogeologic features would seem to preclude contamination of
any of these public water sources by groundwater underlying this site.
- Several meeting attendees expressed concern regarding an unusual prevalence of arthritis in the
area, either related to exposure to site-related heavy metal contamination or from using paint
pigments containing heavy metals. ATSDR medical staff are not aware of any evidence indicating
an association between exposure to heavy metals and arthritis.
Congestive Heart Failure:
- ATSDR staff are not aware of any evidence indicating association between exposure to heavy
metals and congestive heart failure, although studies indicate lead exposure is associated with
hypertension in men.
- ATSDR staff are not aware of any evidence indicating association between exposure to heavy
metals and multiple sclerosis.
The second category is health effects that may be related to the release of sulfur-containing gases, acid mists, and particulates of metals and other soil contaminants by the ongoing commercial activities on the site:
- Some health effects reported by residents living in the immediate vicinity of the site, including
sinus irritation, eye irritation, vomiting, sore throat, and coughing, are consistent with symptoms
associated with air pollution episodes involving atmospheric inversions combined with emissions
of hydrogen sulfide and acid mists. These are likely be related to industrial processes and waste
streams associated with CoZinCo. Individuals with chronic respiratory symptoms or individuals
with allergies, asthma, emphysema or other diagnosed respiratory disorders should consult their
physician for further evaluation. Those individuals or their physicians may contact ATSDR
medical staff for further guidance. ATSDR staff are aware that Colorado DPHE is pursuing
actions against CoZinCo due to possible air violations occurring there.