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PRELIMINARY PUBLIC HEALTH ASSESSMENT

BIG RIVER MINE TAILINGS DESLOGE
(a/k/a ST. JOE MINERALS)
DESLOGE, ST. FRANCOIS COUNTY, MISSOURI


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

On-site and off-site sampling data will be discussed in this section. The concentrations of contaminants found in various environmental media will be compared to values (comparison values) to determine if a contaminant is present at a level that should be further evaluated for the possibility of human exposure and possible public health impact. ATSDR has derived these values from toxicological information presented in their chemical-specific Toxicological Profiles. Environmental Media Evaluation Guides (EMEGs) are derived from the Minimal Risk Levels (MRLs) that is defined as "an estimate of daily human exposure to a chemical that is likely to be without an appreciable risk of deleterious effects (noncarcinogenic) over a specified duration of exposure." EMEGs are based on exposure to a single chemical and do not consider the effects of exposures to chemicals mixtures (ATSDR 1992d). Cancer Risk Evaluation Guides (CREGs) are developed for chemicals that are carcinogenic. CREGs are based on cancer slope factors, which are considered the additional risk of one excessive cancer risk in a population of a million people. Levels above the EMEG (non-carcinogenic) or the CREG (carcinogenic) in any media at a site is called a "contaminant of concern." However, the presence of a contaminant of concern does not necessarily mean that it is a public health threat (ATSDR 1992d).

This public health assessment presents some of those data to demonstrate the amount of contamination present on site and also presents the levels of contamination at other locations where further evaluation is needed.

Toxic Chemical Release Inventory (TRI) databases for the years 1987-1990 were searched to identify facilities that could contribute to the contamination found at and around the Big River Mine Tailings/St. Joe Minerals site. TRI was developed by EPA, and contains information on more than 300 toxic chemicals annually released by certain industries into the air, soil, and water. For the Desloge zip code 63601, the TRI listed one industry that had reported, but no releases were listed. For St. Francois County, the TRI listed two additional industries, but only one had reported releases. None of these industries are considered to be a factor in the contamination at the Big River Mine Tailings/St. Joe Mineral site or in the region.

A. On-Site Contamination

Tailings

On-site sampling has been conducted a number of times. The first major sampling began about 1980, with the report completed in 1983. That sampling was performed by the University of Missouri - Rolla, as requested by MDNR, to determine if the tailings material might be used as agricultural lime. Even though the report concluded that the use of mine tailings as agricultural lime may be acceptable, it stated that caution should be taken because some older piles have much higher concentrations of lead (Wixson et al. 1983). See Table 1 for a summary of sampling events and the range of detected metals in the site pile.

Sampling data were obtained for five of the six piles in the area of concern. Only the data obtained for the Desloge site are listed in the On-Site Contamination section. Data from the other four piles will be listed in the Off-Site Contamination section. Samples were taken 20-40 centimeters (7.8 to 16 inches) below the surface. In the 1983 report, 74 samples were collected from the site and analyzed for lead, cadmium, and zinc.

Nine samples of the tailings, a duplicate, and background samples were collected in May 1988 by an EPA Field investigation Team (FIT). Depth of sampling was not indicated. Analyses were performed for total metals.

The site was investigated again in July 1990 as part of EPA's Listing Site Inspection (LSI). Fourteen tailings samples, including a duplicate, were collected and a complete metal analysis was run on the samples. Three were subsurface samples taken from one point to better characterize the tailings' subsurface, while the remainder were taken at a depth of zero to six inches. Lead levels in the 11 surface tailings samples ranged from 930 parts per million (ppm) to 1,700 ppm, with a single sample from the site's east area containing 13,000 ppm lead (EPA 1991).

Where subsurface samples were taken, lead was measured at 1,300 ppm at the zero- to six-inch depth, 2,500 ppm at the five- to six-foot depth, 1,600 ppm at the ten- to 11-foot depth, and 910 ppm at the 15- to 16-foot depth. Concentrations of cobalt and nickel also increased significantly from the zero- to six-inch depth to the five- to six-foot depth. The LSI's explanation for this increase was that these metals possibly had migrated down from the upper five feet of tailings. It stated that much more sampling and characterization of the subsurface would be needed to confirm that possibility (EPA 1991).

In 1992, EPA directed a Technical Assistance Team (TAT) from Ecology and Environment, Inc., to further investigate the site. Field work for this investigation was conducted August 19-25, 1992. The investigation included lead screening of 405 tailings and soil samples, including 25 subsurface samples, with an x-ray fluorescence (XRF) spectrophotometer. Of the 405 samples, 51 surface and five subsurface samples were submitted to the EPA Region VII Laboratory for verification of XRF results and analyses for total lead, zinc, cadmium, and arsenic. Laboratory results indicated that lead ranged from 25 ppm in the wooded area where no tailings had been dumped to 5,360 ppm in the tailings (E&E 1992).

Analyses from these investigations indicate that lead, arsenic, cadmium, cobalt, zinc, and nickel are present in the tailings (Table 1). Given this wide variation in sampling, a data gap may still exist. ATSDR considers a surface soil sample to be from zero (surface) to three inches deep. This is the depth at which people are most likely to become exposed to contaminants in the soil. However, considering the ease with which the tailings material can be moved, subsurface conditions may be equally important when considering exposure scenarios.

Groundwater

Until the 1990 LSI sampling, there had been very little groundwater sampling at the site. During the LSI, sampling included the drinking water well at the landfill office, four perimeter monitoring wells with one duplicate, four Geoprobe temporary wells, a leachate sample, and four springs. Water samples were analyzed for total (unfiltered) and dissolved metals (samples for dissolved metals are filtered to eliminate suspended particles from adding to the detected results). Only heavy metals were detected at levels of concern. Contaminants of concern are arsenic, cadmium, cobalt, lead, nickel, and zinc (EPA 1991).

Analysis of the landfill office drinking water well indicated that only lead was detected above the comparison value (EPA Action Level = 15 ppb(1)) at 17 ppb total and 14 ppb dissolved. Analyses of other on-site wells, including the monitoring wells, springs, temporary wells, and leachate indicated various contaminants present above comparison values (EPA 1991). The landfill office drinking water well was confirmed to have lead levels above the action level in a follow-up sample collected in August 1992. It contained 16 ppb lead (E&E 1993).

In 1991, two on-site perimeter monitoring wells were sampled for pesticides, volatile organics, base-neutral-acid, total metals, and dissolved metals. They were included as part of a sampling of private wells within a one-mile radius of the Big River Mine Tailings site. Only metals were found (E&E 1991). Refer to Table 2 for a list and range of these contaminants.

Air

In July 1990, the E&E/FIT took air samples using seven air samplers in six locations at and around the site. Samples were taken for a twelve-hour period (from noon to midnight), July 23-28, 1990. Seven samples, plus a field blank were taken for the six day sampling period (7 samples x 6 days = 42 samples, plus 6 field blanks). Two samplers were placed on site to characterize the site and determine if the tailings were being released or transported. One of these samplers was located near the landfill area and the other was placed in the site's northwest section. Two samplers were placed off site in the same location approximately 1,500 feet east of the site to measure the site's influence and to provide a duplicate sample. The remainder were placed in other locations to determine off-site influence of the site at more distant locations, influence from another tailings pile, and to serve as a background. Wind speeds were considered low for the sampling period, so sample levels did not indicate conditions that may be present during strong winds. The sampler located by the landfill area had consistently higher levels than the other on-site sampler. This sampler was influenced by day-to-day activity at the landfill. On the day the landfill was closed, low wind speeds were recorded, and the sampler indicated its lowest level (EPA 1991).

Air samples were analyzed for total metals, with arsenic, cadmium, lead, and zinc being reported in the LSI's Final Report. These detected levels are then compared to ATSDR's conservative comparison values to determine if they should be further evaluated. Arsenic was detected in three on-site samples above the comparison level (CREG) of 0.0002 micro grams per cubic meter (µg/m3) of air. Arsenic levels detected were 0.002 and 0.003 µg/m3 in different on-site samplers and 0.002 µg/m3 in the sampler located west of the Big River pile that could have been influenced by the Leadwood tailings pile. All other samples were reported as undetectable (less than the measurement detection limit) of 0.001 µg/m3. Since the comparison value is below the detection limit, it is not known if arsenic was present in the undetected samples at levels above the CREG. Cadmium was detected in eight samples, but reported as undetectable in the others. The detection limit of 0.001 µg/m3 was above the CREG comparison value of 0.0006 µg/m3. Levels detected for cadmium varied from non-detect at 0.001 to 0.009 µg/m3. On-site lead levels ranged from 0.015 to 1.088 µg/m3, and zinc ranged from 0.011 to 0.473 µg/m3 (EPA 1991). No comparison value is available for lead or zinc. The off-site air sample results will be discussed in the Off-Site Contamination section.

As part of the response action plan, a long-term air quality monitoring network has been established around the Desloge pile. The network consists of four stations that monitor particulate and lead concentrations from the pile. Data generated through this monitoring network will be reviewed and evaluated as part of the on-going public health assessment activities.

B. Off-Site Contamination

Within the area we are discussing in this health assessment are other large tailings piles. Because the Big River Mine Tailings/St. Joe Mineral site is the NPL site under investigation for this document, the influence the other piles have on the environment will be considered in this Off-Site Contamination section. The levels of metal contaminants found in the other tailings piles are listed in Table 3, while the location of the piles can be seen in Figure 2. The LSI report came to the same conclusion, stating "It is important to realize that all of the major tailings piles in this former mining region are contributing to the contamination entering the Big River and its tributaries, and that all are potentially impacting the ambient air. Consequently, the problem is regional and cannot be attributed to only one waste pile" (EPA 1991).

Soil and Tailings

To further highlight the influence of the other tailings piles and the wide use of the tailings in the area, background soil samples were taken during the 1988 site sampling. Three background samples were taken near a gravel road 2.5 miles northwest of the site. Concentrations ranged from 410 to 570 ppm lead, 97 to 99 ppm zinc, with cadmium being undetected. The report did not explain if tailings had been used on this particular road, although it did mention that tailings are used for road material in the area.

Off-site sampling, again conducted as part of the 1990 LSI, indicated that the site was having an influence on the surrounding area. Surface soil samples (0-6 inches deep) were taken at the nearest residence to the site (approximately 100 feet south of the site). The samples contained levels of metals associated with tailings piles that were above both background levels and comparison values. Results indicated 270 ppm cadmium, 16 ppm cobalt, 650 ppm lead, and 13,000 ppm zinc. These were the highest levels of cadmium and zinc detected in the study. Arsenic and nickel were undetected, which is part of the pattern seen from other samples that have been collected and analyzed.

Approximately 1,000 feet south of the site, samples contained levels of 7.9 ppm cadmium, 23 ppm cobalt, 2,200 ppm lead, 430 ppm zinc, 7.6 ppm arsenic, and 21 ppm nickel. Samples collected approximately 1,500 feet south of the site contained 25 ppm cadmium, 13 ppm cobalt, 1,300 ppm lead, 1,100 ppm zinc, nickel 9.6 ppm, and arsenic undetected. Background samples taken at this time indicated the presence of cobalt at 12-16 ppm, lead 64-76 ppm, zinc 35-67 ppm, arsenic 6.2-9.5 ppm, with nickel and cadmium as undetected (EPA 1991).

Approximately 1,500 feet east of the site, soil was sampled and found to contain 3.2 ppm cadmium, 16 ppm cobalt, 370 ppm lead, 180 ppm zinc, 11 ppm nickel, and 8.2 ppm arsenic. Further sampling east of the site at approximately 1.25 and 2 miles did not indicate elevated levels of metals (EPA 1991).

Similar samples were collected west of the site, where the site is not expected to have an influence. These samples contained lead at 450 ppm and 940 ppm. Other metals were also elevated. This could indicate an influence from the Leadwood tailings pile to the west or from tailings used in that area for fill or construction purposes (EPA 1991).

To better determine the influence of the site to the south, a more in-depth sampling was undertaken in 1992. This sampling, conducted by the TAT from E&E, included a number of residential yards to determine the influence the site was having on them. Samples taken from the yards consisted of ten small sub-samples from different locations combined for the total sample. These samples were of surface soil (0 to 1 inch deep). This should be representative of soils where exposure is most likely to occur (ATSDR considers surface soils as 0 to 3 inches deep). Twenty-two samples were taken in the residential area, consisting mostly of yards and quality control samples (E&E 1992). Contaminants detected in yards above comparison values consisted of:

  • cadmium:
  • lead:
  • zinc:
  • arsenic:
  • ranging from 1.3 to 14.2 ppm
    ranging from 184 to 3200 ppm
    ranging from 94.9 to 918 ppm
    non detectable at 20 ppm

    ATSDR uses conservative comparison values to determine if a specific chemical needs further evaluation. Reference levels and their source for the listed chemical are:

  • cadmium:
  • lead:
  • zinc:
  • arsenic:
  • 1 ppm, pica child EMEG
    no value is presently available for lead, as it is undergoing further evaluation
    600 ppm, pica child RMEG
    0.4 ppm, CREG

    Indoor Dust

    During the 1985-1986 DOH Lung Cancer Investigation, indoor dust/dirt samples were taken from household vacuum cleaners to determine possible indoor contamination levels. Household vacuums do not efficiently collect dust and may actually emit dust as they are used. For that reason, dust collected from household vacuums bags cannot be accurately quantified. However, the data were collected and may be useful in identifying areas that need further study. Minimum and maximum levels and the average of metals detected in the vacuum bag samples from the 1985-86 study are listed in Table 4. A single sample measured extremely high at 27,460 ppm of lead. This level was related to hobbies that were done in the house.

    To further complicate relating the indoor dust samples to the site, no background samples of metal concentrations were reported. However, Calabrese 1992 reported that 30% of indoor dust originates from outside soil. These findings, along with the high levels of metals known to be in the tailings piles and found inside the homes emphasize the need for a further evaluation of the indoor dust and the exposure potential. New high efficiency vacuum systems and methodologies are now available to better assess household dust.

    Air

    Air monitoring was first conducted off site by MDNR to determine the effect the Federal tailings pile was having on the immediate area. In this three-year study (1981-1983), a single sampler was located approximately 2,000 feet north of the Federal tailings pile. Particulate matter was sampled and analyzed for lead. The initial sampling period was January-August 1981. Results of the lead analysis were: January-March, 0.14 µg/m3; April-June, 1.09 µg/m3; and July-August, 0.17 µg/m3. The National Ambient (outdoor) Air Quality Standards (NAAQS) for lead per calendar quarter (three months) is 1.5 µg/m3. In the period sampled the standard was not exceeded during the sampling period, but by comparison, the six-year (1985-1990) maximum for a 3-month period at the St. Louis County South Lindbergh monitoring site was less than 0.4 µg/m3.

    The total suspended particulate (TSP) annual geometric mean for the same period was 50.55 µg/m3 for 1981, 35.47 µg/m3 for 1982, and 47.43 µg/m3 for 1983. The NAAQS for the annual geometric mean for TSP is not to exceed 75 µg/m3 (EPA 1991). Given these values, the particulates would have been within the limit. The standard has been lowered and is presently 50 µg/m3.

    A data gap exists because air sampling results are ten years old, and major changes have occurred since the original sampling at the Federal tailings pile. Further, considering the size of the park and tailings pile, the area's environment, and the use of only one air sampler with no established background level, adequate ambient air levels likely could not have been determined. Also, samples were only analyzed for lead when other contaminants are known to be present in the tailings.

    The Federal tailings pile/St. Joe State Park is located near Flat River, Missouri, and is approximately two miles from the Big River Mine Tailings/St. Joe Minerals site. The information was included to demonstrate that there are other sources of dust that can affect the ambient air of the area, and that the site's tailings pile cannot be singled out as the only source of contamination in the area.

    More recent off-site air monitoring related to the Big River Mine Tailings/St. Joe Minerals site was completed as part of the 1990 LSI. In the 1990 LSI sampling, multiple air samplers and a background sampler were placed at different locations around the site. Samples were taken for six consecutive days, for 12 hours a day. Samples were analyzed for arsenic, cadmium, lead, and zinc. Detected arsenic levels ranged from non-detectable at 0.001 µg/m3 to 0.002 µg/m3; cadmium ranged from non-detectable at 0.001 µg/m3 to 0.008 µg/m3; lead ranged from 0.008 to 0.127 µg/m3; and zinc ranged 0.14 to 0.48 µg/m3. Wind speed during the six days of sampling ranged from 1.8 to 5.4 meters per second or 4.0 to 12.0 miles per hour (EPA 1991). A data gap exists in the actual values that may be present during windy conditions because sampling was conducted when winds were calm and were performed for only six days. In this sampling, arsenic levels were detected above the CREG comparison value of 0.0002 µg/m3. Cadmium was also measured above it's CREG comparison value of 0.0006 µg/m3. Levels could be higher when stronger winds are present.

    Air monitoring was conducted at the Federal tailings pile during and for three days after the St. Joe Grand Prix, a major gathering of off-road vehicle riders who use the tailings pile for their activities. Levels of lead in ambient air at the park ranged from 0.68 µg/m3 (the detection limit) to 11.26 µg/m3. Monitoring was conducted October 5-8, 1991, on a 24-hour basis at four stations. The Federal tailings pile makes up a major portion of the St. Joe State Park.

    Groundwater

    Public Water Supply Wells

    Water for the cities adjacent to the Big River Mine Tailings/St. Joe Minerals site is supplied by the Flat River Water District. The water district includes Flat River, Elvins, Desloge, Leadington, Ester, and Rivermines. The water district obtains its water from two main sources, including a well in Desloge and a flooded mine shaft in Rivermines (EPA 1991). Sampling of these water sources was part of the 1985/86 DOH Lung Cancer Study. Sample results indicated that the Desloge well contained five parts per billion (ppb) lead. The Rivermines well (mine shaft) contained a higher level of lead at 49 ppb. At the time of sampling, both wells were below the MCL of 50 ppb (DOH 1986a). The Environmental Protection Agency has since replaced the MCL with a public drinking water Action Level of 15 ppb (EPA 1994).

    MDNR is responsible for monitoring public water systems in Missouri. The agency was asked for the present water analyses of the Flat River Public Water System. Results from sampling conducted in 1991 indicate that the lead level is well within the Action Level of 15 ppb (less than five ppb). Other metals were within limits or undetectable.

    Private Wells

    There is an unknown number of private wells outside of the Flat River Water District. Private well sampling related to the site was first conducted in 1990, but only one well was sampled. That well is located about one-half mile southwest of the site. The owner had complained of having health problems, so an analysis was performed on the well water, including total and dissolved metals and a full target compound list of chemicals. Analysis results indicated total lead present at 29 ppb and dissolved lead at 25 ppb, which are above the 15 ppb Action Level for public water supplies.

    During the 1990 LSI, the E&E/FIT sampled two private drinking water wells. One was the on-site drinking water well at the landfill office, and the other was a residential well approximately 750 feet south of the landfill office. The landfill office well has been previously discussed in the On-Site Contamination section. The residential well contained 26 ppb total zinc and 31 ppb dissolved zinc. No total lead was detected, and the dissolved lead analyses was invalidated. Arsenic, cadmium, cobalt, and nickel were undetectable.

    The E&E/FIT then conducted a more intensive sampling of private wells around the site in 1991. Forty-four private wells (along with four duplicates) were sampled within a one-mile radius of the Big River Mine Tailings/St. Joe Minerals site. Two of the wells were randomly selected and sampled for base-neutral-acids, pesticides, volatile organics, total metals, and dissolved metals. The remaining 42 wells were sampled for total and dissolved metals. All of the samples were sent to the EPA Region VII laboratory for analysis.

    Analyses results showed that no detectable levels of volatiles, semi-volatiles, or pesticides were found in the two wells sampled for those contaminants. Total lead was detected in five private wells at levels ranging from 5.9 to 32.9 ppb. Dissolved lead was found in only two residential wells at 6.6 and 25.6 ppb. The residential well, previously tested in 1990, measured 16 ppb for total lead, while dissolved lead was undetected. Total and dissolved cadmium was not detected in any of the private wells. Total zinc was detected in 19 of the wells sampled, ranging from 20.1 to 457 ppb. Dissolved zinc was detected in 20 private wells with levels ranging from 20.3 to 463 ppb. Several other metals were detected at varying levels, but reportedly at levels below MCLs (E&E 1991).

    In EPA's most recent sampling of the site, 12 residential wells were sampled. One sample was taken as near the wellhead as possible, and another was taken at an indoor tap. This procedure was used to determine if measurable contamination was from the groundwater or the indoor plumbing. Samples were collected from several wells that previously had shown lead contamination. Of the 12 residential wells sampled, one residential well contained lead at 27 ppb, which exceeds the 15 ppb Action Level for public water supplies, and cadmium was present in that well at 12 ppb, which exceeds the 5 ppb MCL. A second well contained lead at 16 ppb at the sample point nearest the well. Another residential well contained cadmium at 6 ppb at the indoor tap, but cadmium was not detected at the well head. Several other water samples were taken during this investigation: from the landfill office, from springs, and for QA/QC confirmation (E&E 1993).

    Surface Water and Sediment

    Surface water and sediment sampling data are available for a 60-mile stretch of the Big River. The data are compiled under the following headings to show the impact from the site and to show how other similar tailings sites in the area are likely to contribute to the river's contamination.

    Surface Water

    In 1982, the U.S. Fish and Wildlife Service (U.S. F&WS) conducted surface water sampling at the Big River Mine Tailings/St. Joe Minerals site. Grab samples were collected during low, medium, and high stream flow conditions. Samples were collected from the Big River, approximately five miles downstream from the site, 16 miles upstream from the site (background) and at Washington State Park, approximately 37 miles downstream from the site. The samples were analyzed for total and dissolved metals. Lead, cadmium, and zinc were determined to be the contaminants of concern in the Big River. The levels for total lead and cadmium had increased for all water levels (low, medium, and high flow conditions) below the Big River tailings pile as compared to background (with one exception). In samples collected at Brown's Ford, approximately 60 miles downstream of the site, contaminant levels had all decreased except dissolved lead, which increased slightly. The maximum total lead concentration of 680 ppb (under high flow conditions) was detected at the Washington State Park sampling site. Concentrations are provided in Table 5.

    During its 1990 LSI, E&E conducted water sampling of the Big River and it's tributaries. At 21 locations a grab sample was taken, including a duplicate. Background samples were collected approximately 16.5 miles and 9.7 miles upstream of the site. Sampling locations included tributaries that drain other tailings piles, as well as the Big River upstream of, parallel with, and downstream from the site. Lead and zinc were the only metals found at elevated levels. Refer to Table 7 for a summary of concentrations detected and the sampling locations.

    Levels of contaminants of concern were lowest at the upstream background sampling points, and increased as sources of contamination (site, tributaries) affected the Big River. Levels of contaminants dropped off downstream as the effect from the tailings decreased.

    Two water quality studies conducted on the Big River were reviewed for this public health assessment. The first study was conducted during the summers of 1962 and 1963. A follow-up study was conducted in 1977 to determine changes and obtain additional data. The studies were designed to determine water quality through species diversity evaluation and water chemistry comparisons to other water bodies in the region. The 1962/63 study determined that a 40-mile stretch of the Big River, downstream of the site was of poorer quality than similar water bodies in the region. The 1977 study determined that the zone of degradation terminated upstream from the Washington State Park, that the degradation had not increased since the earlier study, and that the likely cause of the poor species diversity was from a change of substrate (sediment) because of mine tailings entering the river. The water chemistry data indicated that the mine tailings sites did not greatly change the Big River's water chemistry from comparison rivers (EPA 1978b).

    Sediment

    Concentrations of contaminants in Big River sediment were measured as part of the 1982 U.S. F&WS report. Samples were taken at the same sampling points as the surface water. Lead, cadmium, and zinc were the main contaminants detected. Background samples were taken at the upstream location and contained the lowest levels of contaminants analyzed in the sampling. Sediment samples were then collected at approximately five miles below the site. Results indicated a large increase in the level of contamination compared to the upstream location. Sediment samples taken farther downstream indicated a decreasing trend as distance increased from the site. See Table 6 for contaminant concentrations in the sediment.

    Concentrations of contaminants in sediment were also measured as part of the 1990 E&E LSI report. Samples were taken from the same locations as the 1990 water samples, and consisted of 21 samples, including a duplicate. The sediment samples were composite samples. Background samples were taken at approximately 16.5 miles and 9.7 miles upstream from the site. Sampling locations included tributaries that drain other tailings piles, multiple locations from the Big River along the site, and various locations on the Big River. A summary of the concentrations of cadmium, lead, and zinc, as well as the sampling locations, are listed in Table 8. Concentrations varied, depending on the influence by the site and other tributaries that drained the various tailings piles.

    Aquatic Biota

    Studies were conducted to determine the effects on aquatic biota after the major collapse of tailings into the Big River in 1977. In a study conducted by MDOC, fish (especially bottom feeders) found downstream of the site, contained elevated levels of lead in their edible tissues. The study found that averages for sucker-type fish contained from 0.4 to 0.7 ppm lead in edible fillets, with a few individual fish exceeding 1.0 to 1.28 ppm. The World Health Organization (WHO) has set 0.3 ppm lead as a maximum safe level in food for adults. Because of this report, DOH and MDOC issued a press release discouraging local residents from eating bottom-feeding fish taken from the 50-mile stretch of the Big River from Leadwood to Mammoth Access (MDOC 1980). The Missouri Department of Health presently releases an annual fish advisory. It recommends that carp, redhorse, and suckers taken from the Big River near the site to the where its joins the Meramec River should not be eaten (DOH 1993).

    In a 1982 report, further findings of biodegradation and fish contamination were released by the U.S. F&WS. This study included sampling at a number of locations above (background) and below the site to determine the amount of contamination that had actually occurred. Samples of plants, crayfish, freshwater mussels, and fish were collected. Background samples were taken at Irondale (16 miles above the site). Samples were taken at five miles below the site, at Washington State Park (37 miles below the site), and at Brown's Ford (60 miles downstream of the site).

    Findings of the report indicated that the highest residues of lead, cadmium, copper, and zinc were found in algae below the site. Lead levels were lowest at the background location at 16.3 ppm, while samples five miles below the site measured 1,210 ppm, Washington State Park measured 623 ppm, and Brown's Ford measured 660 ppm. Concentrations of all the metals followed a similar pattern in water willow (an emergent plant). Concentrations of metals were found to be higher in willow roots than in stems and leaves.

    The study also showed that in crayfish, levels of lead and cadmium were found to be elevated at all locations downstream from the site, with the highest concentration measured from the sample point five miles below the site at 140 ppm. At Irondale, background lead levels were 1.4 ppm, a concentration level comparable to levels in uncontaminated laboratory-raised crayfish.

    Freshwater mussels were collected from the same locations on the Big River, and from an additional location at Leadwood. Specimens could not be found at the sample point five miles below the site. The Leadwood sample site is affected by the Leadwood tailings pile. At Brown's Ford, the farthest downstream sample location, the highest mean level of lead detected was 18.5 ppm in the shell and 386.67 ppm in the soft tissue. Concentrations of cadmium, copper, and zinc followed a similar pattern with the highest concentrations occurring at Brown's Ford and the lowest in the background samples at Irondale.

    Samples of edible portions of fish collected at various locations downstream from the site had elevated levels of metals. Lead concentrations were highest in the Redhorse sucker species, with the exception of one catfish that contained 12 ppm lead, taken at Washington State Park. Catfish samples taken from affected areas also had elevated levels of lead compared to background samples. Smallmouth bass were also sampled and had levels of lead above the background level of 0.01 ppm. See Table 9 for a summary of the levels of lead and cadmium detected in the Big River biota.

    C. Quality Assurance and Quality Control

    Various people, organizations, and contractors have been involved in the sampling, research, and analyses at this site, resulting in Quality Assurance and Quality Control (QA/QC) information of varying degrees of accuracy and precision. Some soil analysis levels from the EPA Region VII Laboratory were labeled with a J, indicating data not valid by approved QA/QC procedures. According to EPA, "J-coded data as reported by a Contract Laboratory Program (CLP) lab are chemicals whose concentrations occur above the CAP contract reportable concentration limits for Quality Assurance/Quality Control (QA/QC). Thus, J-coded data are useful for site characterization purposes but have limited value for enforcement proceedings because they represent an estimated value above the contract reportable limit for meeting the contract QA/QC requirements."

    In preparing this public health assessment, DOH and ATSDR have relied on the information provided in the referenced documents and have assumed that adequate quality assurance and quality control measures were followed with regard to chain-of-custody, laboratory procedures, and data reporting. The validity of the analysis and, therefore, the conclusions in this public health assessment are valid only if the referenced information is complete and reliable.

    D. Physical and Other Hazards

    Physical hazards at the site consist mainly of steep drop-offs from the tailings piles themselves or where they lead to a steep drop-off to the river below. An accident occurred when an ORV plunged off one of the tailings piles. Further collapses or washouts of the tailings are possible. The only other physical hazards at the site are old mechanical equipment and old drainage structures. Workers and trespassers are expected to be at risk of harm because of these physical hazards.

    PATHWAYS ANALYSIS

    This section addresses the pathways by which people in the area surrounding the site could be exposed to contaminants at, or migrating from, the site. If it is determined that exposure to chemicals not related to the site is also a concern, these pathways will be evaluated as well. When a chemical is released into the environment, the release does not always lead to exposure. Exposure only occurs when a chemical comes into contact with and enters the body. For a chemical to pose a health risk, a completed exposure pathway must exist. A completed exposure pathway consists of five elements: 1) a source and a mechanism of contaminant release to the environment; 2) transport through an environmental medium (e.g., air, soil, water); 3) a point of human contact with the contaminated medium (known as the exposure point); 4) an exposure route (e.g., inhalation, dermal absorption, ingestion) at the exposure point; and 5) a human population at the exposure point. See Table 10 for a chart identifying the completed exposure pathways at the Big River Mine Tailings/St. Joe Minerals site.

    Exposure pathways are classified as either completed, potential, or eliminated. Completed exposure pathways exist when all five elements are present. Potential exposure pathways are either 1) not currently complete, but could become complete in the future, or 2) are indeterminate due to lack of information. Pathways are eliminated from further assessment if they are determined to be unlikely to occur.

    A time frame given for each pathway indicates whether the exposure occurred in the past, is currently occurring, or will occur in the future. For example, a completed pathway occurring only in the past indicates that exposure has occurred, but does not currently exist and will not exist in the future. Human exposure pathways are evaluated for each environmental medium possibly impacted by site-related contaminants. The toxicological implications of the various exposure pathways identified as being of concern will be evaluated in the Public Health Implications section.

    A. Completed Exposure Pathways

    There are numerous completed exposure pathways occurring at the Big River Mine Tailings/St. Joe Minerals site, in the neighboring communities, and at other tailings piles in the region. Exposure routes are expected to have occurred through ingestion, inhalation, and dermal contact. Considering the contaminants (metals) present at the site and the fact that they are not readily absorbed through the skin, dermal contact has been eliminated as a significant exposure route. Inhalation and ingestion exposures have occurred in the past, present, and will continue until remediation is completed to stop the movement of tailings into the environment. The extent of these exposures is not known because sampling data were not available to determine the level of exposure, the duration of exposure, or the frequency of exposure. The tailings material has been processed and disposed in the environment where human exposure occurs. Weathering (natural decomposition to basic elements) of this material has made the contaminants available to people.

    Air Pathways

    Ambient Air

    Mine tailings from past mining and milling operations were deposited on the ground and piled as high as 100 feet at the Big River Mine Tailings/St. Joe Minerals site. The tailings contain heavy metals. Part of the tailings are powdery, so the material is carried as particulates through the air when the wind or human activities, such as off-road vehicles use, disturb the tailings. Strong winds have reportedly carried clouds of dust from the tailings as far as one mile.

    The fact that similar tailings piles are located throughout the area complicates evaluating how much of the airborne particulates come from the site. Particulates from the site can mix with the particulates from other tailings piles and increase the amount of heavy metals available to people living and working in the area. People living closest to the site/piles would be most affected by site contaminants.

    During a normal work week, there are four full-time landfill employees, with the asphalt contractor having three full-time and two part-time employees. Residential areas adjoin the site on the southeast. When the wind blows, the people who live in those homes or who are working or trespassing on the site are exposed to airborne particulates through inhalation. Incidental ingestion of contaminants is another possible route of exposure.

    Indoor Dust

    When particulates from the site become airborne, they can enter nearby buildings, as described previously, and become part of the indoor air. The collection of vacuum cleaner dust from the area in the 1985/86 DOH Environmental Study supports this theory. People living in the homes near the tailings piles are, therefore, exposed to contaminated particulates through inhalation and incidental ingestion while inside their homes, as well as when they are outside. Indoor exposure may be greater than exposures occurring outside because the particulates are trapped and more concentrated. In addition, other indoor air pollutants (i.e. cigarette smoke, chemicals) could mix with airborne metals and expose residents to higher levels of contamination than those coming from only the tailings piles. The houses within a mile of the site are an estimated 20 to 30 years old. Therefore, people could have been exposed to the contaminated indoor dust for that long.

    Soil Pathways

    Because the tailings are at ground surface, the contaminated piles are considered accessible soils. Because of wind and erosion, the contaminated soils have spread to surrounding areas. A total of seven full-time and two part-time employees who work at the site now and those who worked on the site in the past, as well as trespassers, have been exposed to the contaminants through incidental ingestion and inhalation of particulates.

    As discussed in the Air Pathways section, soils are carried from the site by the wind. When the airborne dust settles, the contaminants from the site become part of the soils in neighboring yards. People who live and work in the area close to the site are exposed to soil contamination through incidental ingestion and inhalation of particulates.

    As with the airborne particulates that settle in the soils outside, the airborne particulates that enter buildings also settle as dust. People, especially crawling infants, are exposed to the contaminants through ingestion and inhalation.

    In the background section of this document, other uses of the tailings were discussed. Tailings have been used for many purposes around the area, including as fill material, road surfaces, and on roads to aid traction in the winter. The number of people that may be exposed to contaminated soils because of these practices cannot be determined. However, people who do come into contact with the relocated tailings can be exposed to the contaminants through incidental ingestion and inhalation of particulates.

    Groundwater Pathways

    Lead was found in some private off-site wells and the on-site drinking water well. Residents, past employees, and the seven to nine present workers at the landfill who drink the contaminated well water, are exposed to lead through ingestion.

    Groundwater flow at the site and in the region has been affected by the extensive mining conducted there. Numerous exploratory drillings have been conducted in the area, providing another path to groundwater. Determining what contamination in the off-site groundwater is attributable to the Big River Mine Tailings/St. Joe minerals site or the other similar tailings piles in the area would be difficult.

    Towns and communities in the vicinity of the site depend on groundwater for drinking and industrial water supplies. There are at least 42 private wells within one mile of the site. Lead has been detected in the municipal water supply, which serves 16,245 people.

    All private wells used in the area may not have been identified and tested. Lead was found in five private wells, and zinc was detected in 20 private wells. This would indicate approximately 12-15 additional people are exposed to lead and an estimated 40-50 people are exposed to zinc through their private water supply.

    Fish Pathways

    Heavy metals from the tailings piles have been washed into the Big River, and have contaminated the water and sediments. Aquatic animals, especially bottom and filter feeders, consume the contaminants with their food. Some of the metals found in the water and sediments can accumulate in animals. Elevated levels of metals found in aquatic animals include lead in fish, crayfish, and mussels; cadmium in crayfish and mussels; and copper and zinc in mussels. People eat fish from the river, especially suckers and catfish. People who eat crayfish and mussels from the Big River are also at risk of becoming exposed to the contaminants. The number of people who catch and eat the contaminated fish, the quantity they eat, and the frequency that the contaminated are eaten is unknown. This leaves a data gap as to the human health risk associated with this specific pathway.

    B. Potential Pathways

    Surface Water and Sediment

    The surface water and sediments in the Big River adjacent to the site have been contaminated with tailings washed and collapsed into the river. People use the river for fishing and other activities, upstream and downstream of the site, but the extent of human activity on the river at the site is unknown. If people come into contact with the water and sediments at the site, some amount of exposure to the contaminants is expected to occur through incidental ingestion and, perhaps, through inhalation of mists and particulates.

    PUBLIC HEALTH IMPLICATIONS

    A. Toxicological Evaluation

    Introduction

    In this section, DOH/ATSDR discuss health effects that could result from exposures to site contaminants. People can only be exposed to a site contaminant if they come in contact with it. People can be exposed by breathing, eating, or drinking the contaminant, or by contacting (skin contact) contaminated water, soil, or air.

    In order to understand health effects that may be caused by a specific contaminant, it is helpful to review factors related to how the human body processes the chemical after exposure. Those factors include the exposure concentration (level), the duration of exposure (how long), the route of exposure (breathing, eating, drinking, or skin contact), the chemical availability (how easily the body absorbs the contaminant), and the multiplicity of exposure (combination of contaminants).

    When exposure occurs, individual characteristics such as age, sex, nutritional status, health status, lifestyle, and genetics influence how the chemical is absorbed, distributed, metabolized (processed), and excreted (eliminated). Together, those factors determine health effects that exposed people may have.

    To determine the possible health effects of specific chemicals, ATSDR searches scientific literature. The information then is compiled and published in a series of chemical-specific ATSDR documents called Toxicological Profiles. Toxicological Profiles are references that describe adverse health effects that could be associated with exposure to a specific chemical in the environment. In addition, they include health guidelines such as ATSDR's minimal risk levels (MRLs) and EPA's reference doses (RfDs), reference concentrations (RfCs), and cancer slope factors (CSFs). When RfDs, RfCs, and MRLs are not available, a no-adverse-effect level (NOAEL) or lowest-adverse-effect level (LOAEL) may be used to estimate levels at which adverse non-cancerous effects are not expected.

    DOH/ATSDR compares contaminant concentrations in different environmental media (soil, air, water, and food), to which populations may be exposed daily, to a variety of health guidelines. This will determine whether exposure to given levels of contaminants is likely to cause an increased risk of developing cancer and/or non-cancerous adverse health effects. ATSDR's MRL is an estimate of daily human exposure to a chemical likely to be without appreciable risk of harmful (non-cancerous) effects over a specified duration of exposure. MRLs are based on human and animal studies and are reported for acute (less than or equal to 14 days), intermediate (15-364 days), and chronic (365 days and greater) exposures. If an individual's daily exposure is below the MRL, adverse health effects are not expected. A RfD is EPA's estimate of a person's daily exposure through ingestion of a contaminant over a lifetime (70 years), that is not expected to result in harmful effects. The estimate includes consideration for people who may be more sensitive to the contaminant's toxicity than the average population. Likewise, a RfC is EPA's estimate for the human population, including sensitive sub-populations, of the daily exposure by the inhalation route likely to be without appreciable risk of harmful (non-cancerous) effects during a lifetime.

    To evaluate exposure to carcinogenic chemicals, EPA has established cancer slope factors (for inhalation and ingestion) that define the relationship between exposure doses and the likelihood of an increased risk of cancer compared with non-exposed populations (controls). Usually derived from animal or occupational studies, cancer slope factors are used to calculate the exposure dose likely to result in one excess cancer case per one million people exposed over a lifetime (70 years).

    ATSDR's estimation of human exposure to contaminated media uses media-specific rates for adults and children. The rates are calculated by multiplying the contaminant concentration by the ingestion rate for an adult or a child, then dividing that number by the appropriate standard body weight (70 kg for adults, 16 kg for a child). The water ingestion rates used for adults and children are 2.0 Liter (L)/day and 1.0 L/day, respectively. ATSDR uses an inhalation rate of 23 cubic meters per day (m3/day) for adults and 15 m3/day for children. Some exposures occur on an intermittent or irregular basis. In those cases, an exposure factor (EF) is calculated that averages the dose over the exposure period.

    The maximum contaminant concentration detected in a particular medium is used to determine estimated exposure. Using the maximum concentration provides an evaluation that is protective of public health.

    Lead

    The presence of lead in groundwater, soils, and dust has led to human exposure. The following discussion will describe how lead contamination in each media has resulted in exposure and what may be expected to result from the exposure.

    Groundwater:

    Lead has been detected in municipal and private drinking water wells in communities around the site. Home plumbing is a common source of lead in drinking water. Lead is also naturally occurring in soils and groundwater at various levels, depending on the region of the country. Lead does not readily absorb through the skin, so dermal contact is not an important route of exposure.

    Lead has been detected in municipal wells at a maximum of 49 ppb, and in private wells at a maximum of 32.9 ppb. Recent monitoring indicates that the level of lead in the public water is well below the current EPA Action Level of 15 ppb (EPA 1994). At that level or above, EPA may recommend an action (such as filtration) be taken to lower the amount of lead in the water. No studies are available to clearly determine how much lead in drinking water will result in increased blood-lead levels in people. For that reason, any lead present in water supplies is a reason for concern.

    Soil/Dust

    Although lead is naturally occurring, in this region the practice of depositing mine tailings at ground level has made lead more accessible to people. Lead is also a problem in older homes where lead paint has been used. In addition to exposure to lead through drinking water supplies, people in the area of the site (and the similar tailings sites throughout the area) have been exposed to lead through incidental ingestion of soils and dust contaminated with lead, both on the site and in yards and homes near the site. Because dust is airborne before it settles to become part of the soil or in-home dust, lead, as particulates, has likely been inhaled as well.

    Lead exposure probably is greatest in the indoor atmosphere, where the contaminant is trapped and dispersed over a confined area. Lead was sampled in household vacuum cleaner dust at a maximum of 5,280 ppm, with a single sample measuring 27,460 ppm (this concentration was present in the vacuum dust in a home where a resident worked with lead products as a hobby). The concentrations are an indication of the amount of lead in dust that was, at some point in time, distributed throughout the households and accessible to the occupants of the homes. Few studies are available that indicate how much lead in dust and soils may result in an increase of blood-lead levels when lead is ingested or inhaled. Madhaven, et.al. derived a "safe" or permissible level of lead in soil (or settled indoor dust, which is considered a type of soil for this evaluation) (Madhaven et.al. 1989). The authors proposed permissible levels of lead in soils ranging from 250 ppm to 1,000 ppm depending on site conditions. The 250 ppm value applies to a worst-case scenario in which an area without grass cover is repeatedly used by children under five years of age, among whom putting objects in their mouths is expected behavior. In this situation, it was estimated that a soil-lead concentration of 250 ppm would add, at most, about 2 micro grams per deciliter (µg/dL) to the blood-lead level of children. Levels of lead in residential soil, in the range of 400 to 500 ppm, are not likely to be considered harmful to children. Lead has been found on site at a maximum of 13,000 ppm and in off-site residential soils (e.g., 2,200 ppm) at levels that are considered unsafe for children. The tailings are also spread throughout the region where children have easy access to them. This constitutes a completed exposure pathway to the contaminated soils and dust that is a public health concern.

    At very high levels of exposure, hematopoietic (production and development of blood cells) and nervous systems are susceptible to harmful effects of lead. Hematopoietic alterations may result in anemia (WHO 1977). The nervous system is another target organ of lead toxicity. Lead damages arteries and capillaries causing cerebral edema, increased cerebrospinal fluid pressure, neuronal degeneration, and glial (non-nervous or supporting tissue of the brain and spinal cord) proliferation (rapid reproduction). Wrist-drop and foot-drop are signs of impairment of the peripheral nervous system (damage of motor nerves). This syndrome occurs mainly from exposure to high lead levels in occupational settings. These alterations are manifested clinically as ataxia (loss of muscle coordination), stupor (unconsciousness), convulsions, and coma. This syndrome is observed in children at blood-lead concentrations of 70 µg/dL. In adults it is observed at 80 µg/dL.

    At lower levels of exposure, such as those for people near the site who are exposed to lead through their water supply and indoor and outdoor soils, other signs of lead toxicity have been observed in children, such as adverse effects on the central nervous system, kidney, and hematopoietic system, as well as decreased intelligence and impaired neurobehavioral development (CDC 1991). This may be due to alterations in neurotransmitter function and the flow of calcium ions. Animal studies have shown that lead can affect reproductive functions in males and females causing sterility, miscarriage, and neonatal death.

    Studies on rodents have shown carcinogenicity of the kidney given large doses of lead, but we have no proof that lead causes cancer in humans (ATSDR 1993b). EPA considers some forms of lead as "B2," or a probable human carcinogens because, despite the inadequacy of studies of lead carcinogenicity (ability to cause cancer) in humans, there are sufficient animal studies that show kidney carcinogenicity.

    Several populations may be especially sensitive to the adverse health effects caused by lead. Pregnant women, fetuses, and children are particularly affected by lead exposure. Children with glucose 6-phosphate dehydrogenase deficiency (most prevalent among blacks) have greater blood-lead levels than non-deficient children with similar exposure. People with sickle-cell anemia may be especially sensitive to neurological effects of lead exposure. Children with pica (a syndrome that causes uncontrolled ingestion of non-food substances) are also at greater risk because they may ingest more contaminated soil. Middle-aged men are at risk for increased blood pressure resulting from lead exposure. In addition, those with dietary deficiencies in calcium, iron, and zinc may be susceptible to the adverse effects of lead. Also, people who work in certain hobbies or industries, such as in the production of storage batteries, chemical substances such as paint and gasoline additives, metal products such as sheet lead, solder and pipe, and ammunition, may also be at greater risk for adverse health effects because of exposure at the work place as well as at home. Those workers may also be exposed to lead through dermal contact because of the organic forms of lead found in some industrial processes (ATSDR 1990b).

    Cadmium

    Cadmium has been detected in tailings, soil and dust, surface water, and biota. Exposure to cadmium at the Big River Mine Tailings/St. Joe Minerals site and the surrounding area follows similar pathways as exposure to lead. Ingestion and inhalation are the main routes of cadmium into the body. Actual exposure levels to cadmium are not known, but the potential for cadmium exposure is present because private yard soil contains up to a maximum of 14.2 ppm, tailings piles contain up to a maximum of 1,870 ppm, and indoor dust contains a maximum of 31 ppm.

    Ingesting low levels of cadmium over long periods of time leads to a build-up of cadmium in the kidneys. This cadmium build-up can cause abnormal kidney function. Evidence exists that lead and cadmium act synergistically. That means that exposure to one can enhance the toxicity of the other on the kidney (ATSDR 1989a). Ingestion of cadmium can also cause bones to lose calcium and become fragile and break easily. It is not known if cadmium exposure affects reproduction or harms unborn babies. Inhalation of low levels of cadmium over several years can lead to similar health effects as seen from ingesting cadmium. Workers who inhale cadmium for a long time may have an increased risk of getting lung cancer.

    Evidence that cadmium inhalation can cause cancer in humans is rather weak, but it has been shown to cause lung cancer in rats (ATSDR 1993c). According to the EPA, cadmium is classified as a "B1" carcinogen. This means that it is a probable human carcinogen because, although limited human studies exist, there are sufficient animal studies that show cadmium carcinogenicity (ATSDR 1989a).

    Inhalation of cadmium has the possibility of causing cancer in humans. Cadmium was measured at a maximum concentration in air of 0.009 µg/m3 during six half-days of sampling during EPA's Listing Site Investigation. That level was detected in a 12-hours, 6-day sampling period and may not represent the true value of cadmium in the air. Therefore, information available may not be representative, and cancer risk cannot be adequately addressed. The level is above ATSDR's Cancer Risk Evaluation Guide value of 0.0006 µg/m3 where the additional risk of one excessive cancer in a population of a million is possible.

    Arsenic

    Arsenic is a natural element in the environment, and low levels are present in soil, water, and air. Soil contains the most arsenic, with average levels of about 5 ppm. Levels in food usually range from 20 to 140 ppb, and levels in water are normally about 2 ppb. Mean levels in ambient air usually range from less than 0.001 µg/m3 in remote areas to 0.02 to 0.03 µg/m3 in urban area with contributing industries such as coal-fired power plants (1993a).

    Arsenic has been detected in tailings, soils, and dust on site and in the surrounding area of the Big River Mine Tailings/St. Joe Minerals site. Pathways and the opportunity for exposure to arsenic is similar to lead and cadmium. Levels at the site and certain locations around the site, including household dust, have been found to be slightly elevated. Arsenic in tailings was detected at a maximum level of 14 ppm and in indoor dust at a maximum of 13.2 ppm. Residential soils near the site were shown to contain a maximum of 20 ppm.

    It is not known what levels of exposure are actually occurring in the area, but low levels of inorganic arsenic (ranging from 300 to 30,000 ppb in food) can cause irritation to the stomach and intestines, with symptoms such as pain, nausea, vomiting, and diarrhea. Other effects one might experience from ingesting arsenic include decreased production of red and white blood cells, abnormal heart function, blood-vessel damage, and impaired nerve function, which causes a "pins and needles" sensation in the hands and feet (ATSDR 1993).

    There is clear evidence from studies in humans that exposure to inorganic arsenic may increase the risk of cancer. Most studies have involved occupational settings where most researchers observe that the risk of lung cancer increases as a function of exposure level and duration. Other studies suggest that people who live near smelters, chemical factories, or waste sites with arsenic, may have a small increased risk of lung cancer (ATSDR 1993). Arsenic has also been shown to cause cancer when it enters the body by the ingestion route. The main carcinogenic effect from ingestion of inorganic arsenic is skin cancer, but it may also increase the risk of internal tumors (mainly of the liver, bladder, kidney, and lung). According to EPA, arsenic is classified as a "A" carcinogen, which means that arsenic is a human carcinogen (ATSDR 1993a).

    Inhalation of arsenic is known to cause cancer in humans. Arsenic was measured at a maximum concentration in air of 0.003 µg/m3 during six half-days of sampling for EPA's Listing Site Inspection. That level was detected in a 12-hours 6-day sampling period and may not represent the true value of arsenic in the air. Therefore, information available may not be representative, and cancer risk cannot be adequately addressed. The level is above ATSDR's conservative Cancer Risk Evaluation Guide value of 0.0002 µg/m3 where the additional risk of one excessive cancer in a population of a million is possible.

    Zinc

    Zinc has been detected at elevated levels in the tailings, soil, air, household dust, and river water. Zinc is an essential element in the human diet and toxicity due to environmental zinc is rare. Zinc intoxication occurs mainly due to excessive supplement intake. Exposure pathways to zinc in the region would follow the patterns of the other metals and enter the body through ingestion and inhalation. Exposure to small amounts of zinc compounds occur every day from the food and water we consume. Average zinc intake in the diet ranges from 7 to 16.3 milligrams (mg) per day. The levels of zinc that produce adverse health effects are usually much higher than the Recommended Daily Allowances (RDAs) for zinc of 15 mg/day (men) and 12 mg/day (women). If large doses of zinc (10 to 15 times higher than the RDA) are ingested for even a short time, stomach and digestion problems might occur. Too much zinc might also interfere with the body's immune system and the body's ability to take in and use other essential minerals such as copper and iron. Normally, zinc leaves the body in urine and feces.

    Taking in too little zinc is as much of a health problem as taking in too much zinc. Without zinc in the diet, people can experience loss of appetite, decreased sense of taste and smell, slow wound healing, and skin lesions (ATSDR 1989b).

    Health effects from excessive zinc exposure are not expected to be a problem from normal exposures in the area. If other sources of high zinc exposure or if dietary supplements of zinc are taken, the additional exposure from the site could increase values above the recommended intake.

    B. Health Outcome Data Evaluation

    The Missouri Department of Health 1985-86 case-control study of lung cancer deaths in the Flat River area concluded that smoking was the strongest risk factor contributing to the excessive number of lung cancer deaths. The study revealed that smokers had more than 30 times the risk of lung cancer than did non-smokers. It also found that underground miners had approximately a three-fold increased risk of lung cancer as compared to non-miners. Data were also obtained from birth certificates that indicated a greater percentage of mothers in the Flat River area smoke, and they smoke significantly more cigarettes than other mothers in St. Francois county or in the state as a whole.

    For the Preliminary Public Health Assessment the zip code 63601 for the city of Desloge, which includes the cities of Elvins, Ester, Flat River, Leadington, and Rivermines was used as the geographic area of interest.

    Cancer deaths by type of cancer, age group, sex, and total observed cancers were compared to the expected state rate for the years 1980 to 1990. In the analysis of deaths by type of cancer, we noted that combined male and female lung cancer deaths were significantly higher than expected for the 15-44 and 45-64 age groups. Males consistently had a significantly higher-than-expected lung cancer death rate in those groups, and in the 65-and-older group. In the 65-and-older age group, oral and liver cancer deaths were also significantly higher-than-expected when both sexes were combined, and oral cancer deaths were significantly higher when only males were considered. For females only, the 65-and-older group was significantly higher than expected for thyroid cancers, but the numbers were small (2.0 versus 0.3) and may not be meaningful because such findings may occur by coincidence. Females also had a significantly higher-than-expected number of leukemia deaths when all age groups were combined, with ten deaths observed, versus 5.4 expected deaths.

    Total deaths (male and female and all age groups) from lung cancer were significantly higher than expected, with 118 deaths observed, compared to an expected number of 90.1. Combined male and female cancer deaths for all types of cancer in the 65-and-older groups were significantly higher-than-expected, with 240 versus 204.6. Total cancers (all types) observed for all age groups and both sexes were significantly higher-than-expected, with 354 versus 308.4.

    Cancer incidence for the zip code 63601 was compared to nation-wide data from the National Cancer Institute SEER program for cancer registry data for the years 1985 through 1991. Lung cancer incidences were elevated for the age groups 45-64, and 65-and-older in males, and the age group of 45-64 for females. The total for both sexes indicated only the 45-64 age group to be elevated. Other types of cancer showing an elevated incidence rate were liver cancer in the male 65-and-older age group. In females, cervix-uteri showed elevated incidence in the 65-and-older age group, non-Hodgkins in the 65-and-older age group, and other cancers in the 45-65 age group. The total for both sexes indicated an increased incidence only in lung cancer in the 45-64 age group, and non-Hodgkins in the 65-and-older age group.

    Of continuing concern is the consistent, significantly higher-than-expected number of male lung cancer deaths for all age groups except the zero-to-14 age group. Also of concern is the total number of lung cancer deaths for both sexes of all age groups, and the total of all types of cancer for all age groups and both sexes, compared to the expected state rate. Lung cancer incidence rates were also high for males in the 45-64 and 65-and-older age groups, and for the female 45-64 age group.

    For 16 employees and residents (15 adults, 1 child) of the St. Joe State Park area, which contains the Federal tailings pile, who would have varying degrees of exposure to the tailings, blood-lead levels were analyzed to determine if they were being affected by exposure to the tailings. Of the 16 tested, two adults had blood-lead levels above five µg/dL, at 10 and 12 µg/dL. Follow-up tests on these two individuals included a resampling of the blood-lead and a questionnaire to determine other possible routes of exposure to lead. The second blood-lead sampling yielded results of 10 µg/dL for the person measuring 10 before and 17 µg/dL for the person who previously had a measurement of 12 µg/dL. Results from the questionnaires suggested other possible routes of exposure.

    We reviewed available statistical data on birth outcomes for the years 1980 through 1991. The fetal deaths, birth defects, and low birth weights occurring in the area were not significantly different from those predicted by the state rates.

    C. Community Health Concerns Evaluation

    Community health concerns are being addressed through the on-going interactions with the Citizens Advisory Group, interactions with community members through the current health study, and through interactions with local officials. Concerns gathered during the public comment release of this document are addressed in Appendix C.


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