PUBLIC HEALTH ASSESSMENT
DEPUE/NEW JERSEY ZINC/MOBIL CHEMICAL CORPORATION
DEPUE, BUREAU COUNTY, ILLINOIS
The DePue/New Jersey Zinc/Mobil Chemical Site is in DePue, Bureau County, Illinois. Zinc smelting, production of zinc compounds, and production of inorganic chemical products took place at the facility. The past and present owners of the site, collectively known as the DePue Group, have ceased all production and have completed several clean up tasks, which were included in a 1995 Interim Consent Order. Additional cleanup activities are in progress and are being monitored by the Illinois Environmental Protection Agency (Illinois EPA). The site is under consideration for inclusion in the federal Superfund program and was included on the proposed National Priorities List in 1997.
Exposure of workers and residents to air emissions on and off the site probably took place in the years before environmental regulation. Inorganic and metal by-products, generated from various production efforts, migrated onto nearby public and private properties, Lake DePue, and conservation areas. The main site operations were located in the center of town, and homes were built around it.
In 1992, Illinois EPA collected and analyzed soil samples and presented this information to the U.S. Environmental Protection Agency (USEPA) for consideration as a federal site (Illinois EPA, 1992). The data were also presented to the Illinois Department of Public Health (IDPH), which consulted with the Agency for Toxic Substances and Disease Registry (ATSDR). The contaminants of interest are metals. IDPH and ATSDR developed a health consultation which recommended that:
- (1) public access to on-site areas be restricted,
(2) procedures to suppress dust generation and migration during on-site removal/remedial operations, including demolition activities, be implemented,
(3) additional studies to better characterize the extent and degree of off-site soil contamination in residential yards and where areas of significant contamination are identified to consider strategies for reducing exposures to contaminated soils be considered, and
(4) community health education initiatives, informing residents on methods to reduce their exposure to contaminated soils and dust be continued (ATSDR, 1992).
Most of those recommendations either have been implemented or are under consideration and were included in the 1995 consent order.
In response to questions from Illinois EPA about the need for an emergency cleanup action, IDPH conducted biological screening of volunteers in September 1993 to collect blood and urine samples, which were analyzed for cadmium and lead. Three individuals, one in each of the three types of samples collected, had an elevated concentration. Further investigation of those three individuals revealed lead and cadmium sources in their homes or workplaces. No immediate public health hazard was demonstrated by the blood and urine screening, and a recommendation for emergency cleanup action did not appear to be necessary.
Through the 1990s, a number of actions have been taken by the site owners. The growth of groundcover on the site properties has been markedly improved, and a dust suppression program has been implemented. Air sampling was conducted until sufficient data were available to demonstrate that air standards for metals were not exceeded. An interim water treatment facility was built and became operational in 1997. A program to divert clean surface water around the site is being implemented. Work on the South Ditch leading into Lake DePue has begun, and the work plan for the site-wide remedial investigation is under consideration. The site has been very dynamic, and a sizeable investment has been made by the DePue Group to reduce exposures and to limit the migration and erosion of wastes.
Although biological sampling in September 1993 did not demonstrate any problematic exposures in the volunteers, workers and residents were likely exposed to contaminants in the past. Several of the site areas have been improved since 1992; however, heavy metal contamination remains. Metals do not break down in nature, so metals that were deposited on surface soils, unless physically disturbed, will be present for many years to come.
IDPH considers the site a public health hazard because of potential exposures to contamination in surface soils and sediments and because of likely long-term, past exposures. IDPH and ATSDR will continue to evaluate the need for any further health follow-up activities when additional information from the remedial investigation and cleanup activities becomes available.
IDPH has conducted educational programs that showed residents how to reduce exposures to site-related metals in soil. Education targeting local health professionals has also been conducted. IDPH will continue to coordinate educational efforts in the future as deemed necessary.
State-owned properties impacted by the site, including conservation areas and Lake DePue, are managed by the Illinois Department of Natural Resources (IDNR). IDNR is conducting independent investigations of the impact of metals on these areas.
In cooperation with the Agency for Toxic Substances and Disease Registry (ATSDR), the Illinois Department of Public Health (IDPH), evaluated the public health significance of the DePue/New Jersey (NJ) Zinc/Mobil Chemical Site in DePue, Illinois, based on available data. More specifically, IDPH determined whether adverse health effects are possible and recommended further actions to reduce or prevent possible health effects.
The site is a former primary and secondary zinc smelting facility. From early in the century to the 1940s, coal was the principal fuel. Natural gas was used from the 1940s to the 1970s. Acids and fertilizers were produced on the site as well. The past and present owners of the site are collectively known as the DePue Group. The DePue Group entered into an Interim Consent Order in 1995 with the Illinois Environmental Protection Agency (Illinois EPA) and the Illinois Attorney General that required several cleanup activities. The DePue Group and their contractors have:
- increased security and restricted access to the site properties;
- implemented a dust suppression program;
- completed a focused remedial investigation (RI) of the South Ditch leading to Lake DePue;
- submitted a focused feasibility study of the South Ditch for clean up of the South Ditch;
- developed an interim heavy metal water treatment system;
- developed a program to divert clean surface water away from the site;
- completed a cleanup of the former vanadium catalyst disposal area;
- removed materials from the former settling ponds south of Marquette Street; and
- continued the activities associated with the closure of the "gypstack" (short for the phosphogypsum stack) area and the main operations areas.
In recent years, the DePue Group placed air monitoring stations around the site, and samples were collected for 14 months. The results of this sampling effort demonstrated that current emissions were not violating air standards. Plans for the assessment of other contaminated areas are being reviewed by Illinois EPA.
The Illinois Department of Natural Resources (IDNR) is conducting investigations associated with metals found on state property and nearby conservation areas. Lake DePue was dredged in the 1980s to increase the depth of the water body, and the metal-containing sediments were placed in conservation areas.
The site was listed on the proposed National Priorities List in March 1997.
The site is south of Illinois Route 29 in southeastern Bureau County, Illinois (Figure 1). About 10 miles northwest of the site is Princeton, the county seat, with a population of about 7,200 people (Figure 2). Spring Valley, population 5,200, is the closest commercial/industrial community and is about 6 miles upstream on the Illinois River. A non-industrialized community, Tiskilwa, has a population of about 1,000 people and is 10 miles southwest of DePue. Tiskilwa was selected by Illinois EPA as a comparable community for some background environmental sampling (Illinois EPA, 1992). Bureau County is largely zoned for agricultural use. The original development of DePue began on farmland at the turn of the century. This area was chosen for development in response to the market demand for zinc and because of the abundance of local coal and railroad access. Figures 3 and 4 show the proximity of DePue and community landmarks to the site areas.
The following sections describe several distinct areas of the site.
The Main Zinc Operations Area
Former zinc smelting operations occurred in the center of the village of DePue. Primary zinc smelting began early in the century and used coal as fuel until the 1940s. Natural gas was used as fuel for smelting from the early 1940s until the 1970s. Sulfuric acid was made until 1948 by using sulfuric dioxide gas produced during the coal-fired roasting process and vanadium pentoxide as a catalyst. Zinc ore from Elmo, Wisconsin, and Gilman, Colorado, was processed at a rate of 71,000 tons annually in 1967 (Illinois State Geologic Survey, 1986). The smelting and coal cinder wastes, called "the gob pile" or the "cinder bank," is found near the former smelting operations. The gob pile covers about 15 acres along Marquette Street (Figure 4) and contains solid smelting wastes and coal cinders. A sample from the gob pile collected during a 1975 inspection contained elevated concentrations of metals (Illinois EPA, 1975). Gibb and Cartwright (1982) determined that a 1-foot to a 5-foot layer of cinders covers about 90 acres of the site. Ridges formerly located north of the gob pile contained some zinc and barium wastes and were known as the "lithopone ridges." In 1989, the gob pile and two lithopone ridges were covered with 18 inches of soil and were seeded.
Eleven piles of solid waste were measured during a site inspection in 1993 (Illinois EPA,1993a). Black fines, briquettes, bricks, concrete, construction debris, pieces of barrels and iron, rock, cinders, ditch dredge, lime, railroad ties, white crystals, and wood pieces were described in the inspection report (Illinois EPA, 1993a).
Only a few of the original site buildings remain. One building was converted to a facility to house the mechanical and monitoring systems for the water treatment plant, which collects surface water and shallow groundwater, removes metals, and returns the treated water to the South Ditch. Fencing surrounds the main operations area.
North and west of the old smelting area is where inorganic fertilizer processing occurred. In 1966, the area was developed to process phosphate ores and other inorganic chemicals for acid and fertilizer productions. This fertilizer area shares a fence line with East Street. An acid plant was built to serve the fertilizer operation where phosphate ore was converted to phosphoric acid using sulfuric acid. This plant used Illinois River water for cooling and discharged non-contact cooling water through two cooling ponds on the north bank of Lake DePue. In 1980, a sulfuric acid spill on the site led to the partial evacuation of the village because of reported hydrogen sulfide gas in the air (Illinois EPA, 1983). One death and two injuries were attributed to this accident. Shortly thereafter, the company modified the sewer systems to isolate the fertilizer plant drainage from the village of DePue's system.
Underground tanks storing diesel fuel and gasoline formerly existed in this area. An incident report was filed with the Illinois EPA Leaking Underground Storage Tank (LUST) program in 1990 when, during removal and closure of three underground storage tanks, petroleum-related soil quality impacts were discovered. Exploratory digging, drilling, and monitoring well installations were conducted to determine the extent of the contamination. The Illinois EPA LUST program directed the cleanup activities.
In 1992, a radiation detector alarm was triggered at a scrap metal facility that was receiving site materials. The Illinois Department of Nuclear Safety conducted a radium survey of the site in April 1992. Radium was present at the site, but the radiation levels measured did not present a health risk to the on-site workers (IDNS, 1992). Radium is a naturally-occurring element in phosphate rock.
Areas South of the Main Operations
Marquette Street connects downtown DePue to the subdivision on the bluff to the northeast known as "White City." Pedestrians and bicyclists frequently use the sidewalk bordering the site along Marquette Street. In the past, green-tinted water pooled near the sidewalk. The DePue Group has installed a groundwater collection system and has raised the sidewalk in recent years to alleviate the standing water.
The South Ditch, which is south of Marquette Street, south of the former main operations area, and north of Lake DePue, has been the objective of a focused remedial investigation (RI). Cyclone fencing has been installed around the South Ditch, and sampling and cleanup actions are progressing. A recent ecotoxicological investigation of the sediments collected from the South Ditch resulted in the mortality of midge larvae and amphipods in the laboratory (Golder, 1997).
The Gypstack Area
The gypstack (short for phosphogypsum stack) is north of DePue on Illinois Route 29 (Figure 4) and is the largest site area. Gypsum was the main byproduct of the fertilizer manufacturing process and was pumped overland to this area. A clay barrier is under a portion of the gypstack, but information about the extent or thickness of the clay barrier is limited. During the 1970s, some local farming interests accepted gypsum, presumably to be used as fertilizer. The gypstack was designed with a water collection system that was part of a closed-loop management system. Today, grading has leveled the stacks, improvements have been made to manage precipitation and surface water, a vegetative cover has been established, and security has been improved with the installation of fencing and gates.
Lake DePue is an "oxbow" lake and part of the backwater of the Illinois River (Figure 3). The lake and nearby creeks are part of Illinois' largest watershed, the Illinois River basin. Lake DePue is about 525 acres in surface area, has about 11.3 miles of shoreline, and has a maximum depth of 1.8 meters (Illinois EPA, 1978). Soil erosion contributes to the sedimentation and filling-in of backwater lakes. A narrow channel connects the lake to the Illinois River at river mile 221.
Lake DePue was dredged by the state in 1972, and again from approximately 1979 through 1982. Sediments were removed from the bottom to deepen the part of the lake used for an annual boat racing event. The dredged material from the lake bottom was placed on land between Lake DePue and the Illinois River. According to a 1983 preliminary assessment developed for USEPA Region V, approximately 188,000 dead fish were reportedly observed in Lake DePue in August 1974 (USEPA, 1984).
The water and sediment quality of Illinois lakes and creeks have been monitored, sampled, and evaluated by Illinois EPA since the 1970s. The Illinois Water Quality Reports developed by the Illinois EPA rate the uses of surface water bodies throughout Illinois. In 1992, Illinois EPA determined that Lake DePue had been impacted by metals, siltation, and suspended solids, caused mainly by industry and agriculture (Illinois EPA, 1994).
The Illinois Water Quality Report published in September 1996 determined that elevated levels of zinc in river and stream sediments impacted more waterway miles in Illinois than any other parameter monitored (Illinois EPA, 1996). Lake DePue is also part of the Illinois Fish Contaminant Monitoring Program, for which fillets of lake fish are sampled every odd-numbered year (Illinois EPA, 1994).
In October 1992, the Illinois Department of Conservation (now part of IDNR), IDPH, and the U.S. Food and Drug Administration (USFDA) collected five fish species from Lake DePue. A USFDA laboratory filleted and analyzed the five fish species for some metals (USFDA, 1993). Zinc was the most concentrated metal analyzed in the fish flesh (Table 9).
Another area under consideration is off-site residential, public, and private properties (Figures 3 and 4). Rail lines, roadways, and other building projects may have used smelting waste for fill material because of its strong load-bearing properties. Off-site properties contain metals in yards, gardens, and play areas (Tables 3 and 4).
Public Health Involvement
During an Expanded Site Inspection in March 1992, Illinois EPA collected 37 soil and sediment samples from areas on and off the site (including two background soil samples from the city of Tiskilwa and one background sediment sample from Lake Turner). During the sampling event, five surface water samples (including one background sample) were collected (Illinois EPA, 1992). The results (included in Tables 1 through 7) were forwarded to IDPH, which shared the information with ATSDR. A health consultation dated July 28, 1992, concluded that conditions warranted additional sampling activities (ATSDR, 1992).
To further characterize residential neighborhoods, IDPH collected 65 composite surface soil samples in December 1992 from the top inch of surface soil. Samples were collected from "metal-neutral" areas that were not located near any roads, drives, buildings, drip lines, burn barrels, fences, or similar structures. Targeted samples were collected from areas around the perimeter residential neighborhoods, which surround the main operations area. In addition, random samples were collected from the southern, eastern, and western residential areas. These surface soil samples were analyzed for cadmium, lead, and zinc (Table 4).
During 1993 and 1994, IDPH staff collected indoor residential dust samples from 15 homes in DePue. Those samples were analyzed for cadmium, lead, and zinc (Table 11). House dust is an environmental medium that is readily available to residents, especially younger children. If good housekeeping and personal hygiene practices are not followed, metals can accumulate in house dust from several environmental and consumer sources.
Illinois EPA collected additional environmental samples in April 1993, which included water and sediment samples from east and west of the Marquette Street storm sewer grate, from the north end of the South Ditch, and from two samples from an on-site surface water ditch that runs along the south edge of the lithopone stacks (Illinois EPA, 1993b). USEPA also sent contractors to the area for additional environmental samples in the spring of 1993 (Ecology and Environment, 1993). The results of those sampling events are included in the appropriate areas of Tables 1 through 7.
In September 1993, IDPH, with the assistance of the Bureau County Health Department, Illinois EPA, and contractual nursing staff, conducted lead and cadmium screening of volunteers from the community to learn if an immediate public health hazard existed. A temporary clinic was established at the DePue Veterans of Foreign Wars (VFW) building for three days. Blood and urine samples were collected and analyzed for cadmium and lead (Tables 12 through 14). In total, 110 individuals volunteered for the screening. One child had an elevated blood lead level. One senior citizen had an elevated urine cadmium level, and one other adult had an elevated blood cadmium level. Workplace and residential metal sources were identified for those three individuals.
Former DePue residents have given IDPH and Illinois EPA information about nine persons who have been diagnosed with multiple sclerosis (MS) (IDPH, 1996). With funding and technical assistance from ATSDR, IDPH contracted with staff at the University of Rochester who specialize in MS and biostatistics. The nine MS cases have been confirmed. A report that summarizes this investigation is included as Attachment 1. These findings were presented in a workshop at the Bureau County Health Department, which IDPH and the National MS Society cosponsored in September 1998. Dr. Randolph Schiffer reported that although zinc exposure has been theorized as an environmental cause of MS, there is no clinical evidence to substantiate this claim.
IDPH and Illinois EPA have provided educational activities and materials for the community and health care professionals. In 1992 and 1997, IDPH provided workshops for the medical staff at St. Margaret's Hospital in Spring Valley and for St. Mary's Hospital in Princeton that discussed the clinical implications of metal exposures. A workshop on MS was presented in 1998. Educational efforts, public meetings, and information have been provided to community members on methods to reduce exposures to metal residues, including discussions about nutrition, dust control methods, thorough house cleaning, and gardening issues. The information, written in Spanish as well as English, and interpreters have been provided for the Spanish-speaking participants at public functions.
Illinois EPA regularly organizes public meetings with the DePue Superfund Citizens' Advisory Committee. The Bureau County Health Department is involved with continuing educational efforts concerning ways families can reduce common heavy metal exposures.
IDPH acknowledges the assistance of residents, community leaders, and local officials, including the village of DePue president, the village of DePue city clerk, the Superintendent of Schools, County Board Members, and Bureau County Health Department personnel during the development of this document. The organizations that have provided information and assistance include USEPA, Illinois EPA, IDNR, the Bureau County Health Department, and USFDA. Managers and consultants for the DePue Group have provided site tours and information.
IDPH staff made the first site visit in the spring of 1992 shortly after the receipt of the Illinois EPA sampling results from earlier that year. During the first week of December 1992, IDPH staff collected surface soil samples from residential areas and conducted a door-to-door survey. Several visits were made to sample house dust and to prepare for biological screening held at the VFW hall in September 1993.
IDPH staff most recently visited the area on September 29, 1998. On September 24, 1997, IDPH staff attended a tour, which was conducted by the DePue Group, of the interim water treatment plant, the gypsum stack, the South Ditch, the managed wetlands, and other site areas. On several occasions, IDPH staff has been invited to present to the DePue Citizens' Advisory Committee, which meets every month to follow the progress made on the site. IDPH staff has also been invited to speak during Illinois EPA-sponsored functions and public meetings in the community.
According to the 1990 census, about 2,430 people live within 3 miles of the site, and 1,729 people live within 1 mile of the site in the village of DePue. Approximately 565 individuals in the village are of Hispanic descent. The closest residential properties include approximately 20 homes that share the site's western fence line along East Street. The older section of the village is south of the site.
DePue experienced a population shift when site operations began to downsize in the 1980s. At one time, as many as 3,000 workers were reportedly employed at the site. Today, the on-site workers include four water treatment plant operators and a site manager. In addition, contractors hired for short-term tasks associated with cleanup activities frequently visit the site. Contractors hired for regulatory compliance activities visit on occasion, but their home offices are in other communities.
In 1990, the median year of construction of DePue homes was 1939 and the median value of housing units was $24,900. The median DePue household income in 1989 was $21,250, and 100 households had incomes at or below the poverty level. On May 18, 1993, Illinois EPA staff counted 446 occupied homes within the area of potential contamination (Illinois EPA, 1993a).
A school is south of the site in the old section of DePue. In 1992, approximately 400 students, representing about 250 families, in grades K through 12 were enrolled. Some families transport their children to private schools in neighboring communities. A day care facility operated by a church is across the street from the school. A nursing home is on a bluff to the north, overlooking the river valley.
Natural Resource Use
Bureau County is largely rural and zoned for agricultural use. About 94 percent of the county is farmland, with approximately 2,000 farms.
Drinking water in DePue is obtained from an aquifer almost 1,500 feet deep that serves nearly the entire village. According to the most recent census information, nine households in the area have private wells that are upgradient of the former plant site.
Surface water runoff from the site to Lake DePue occurs especially following rain or snow. Annual precipitation is roughly 36 inches. The 100-year flood plain along the Illinois River includes most homes that border Lake DePue. The South Ditch is also within the 100-year flood plain.
Lake DePue is used for swimming, fishing, boating, jet-skiing, and boat races. The lake is easily accessible from the public park and boat ramp on the northern bank. Tourist attendance at annual boat races and other recreational uses of the lake has been estimated at 60,000. The village has been the host to boat races 23 times since 1961 (Village of DePue, 1996). The State has dredged the lake in the past to deepen the waterway for the races. The lake appeared to be well stocked during the fish sampling in October 1992.
Several municipal storm sewer pipes and the village of DePue's water treatment plant also discharges to the lake. The community of DePue has hopes of developing a better-known recreational area to attract additional tourists to their village to boost the local economy.
Waterfowl frequent the local habitat. Several locally-managed conservation areas are adjacent to the Illinois River near DePue. Between the lake and the river is an area managed by IDNR to attract ducks during hunting seasons. Some parts of these wetlands are suspected to have been the place where sediments removed from Lake DePue were deposited after dredging by the State (Illinois EPA, 1997a). In 1993, IDPH staff observed hunters carrying game.
One resident living near the site reportedly died of exposure to hydrogen sulfide following an accident at the facility in 1980. The accident occurred when a sulfuric acid spill resulted in an apparent hydrogen sulfide gas release during fertilizer manufacturing. Residents were evacuated from the area. The village's sewer system was later modified to prevent a similar occurrence.
During some public meetings, a few residents asked about cancer prevalence rates. Statewide reporting is required for several cancer types and data are collected by the IDPH Division of Epidemiological Studies. In February 1994, the incidence of cancer in DePue was analyzed for cancer cases reported to IDPH from 1987 to 1991. Forty cases of cancer were observed within the DePue zip code area (61322) with 45 cases expected. This difference was not statistically significant (IDPH, 1994).
In September 1993, IDPH organized blood and urine screening for lead and cadmium. IDPH invited the community to participate through notices in utility company mailings, meetings, and with the assistance of community leaders and other private and public organizations. Blood and urine samples from 110 volunteers were analyzed for cadmium and lead (Tables 12 through 14). One child had an elevated blood lead level. One senior citizen had an elevated urine cadmium level and one adult had an elevated blood cadmium result. Further investigation revealed potential workplace or household lead and cadmium exposure sources for the three individuals.
Some community members reported to Illinois EPA and IDPH information regarding nine people who have resided in DePue and have been diagnosed with MS. IDPH consulted with ATSDR regarding these concerns (IDPH, 1996). Medical records of these cases were collected after consent was received. A neurologist specializing in MS reviewed and confirmed the records. The statistical evaluation of these data was presented in a report provided to IDPH (Attachment 1). This investigation statistically identified an elevated incidence rate from the period of 1971-1990. It did not attempt to identify any mechanisms underlying the development. The specific factors leading to MS remain unclear to medical researchers everywhere and was not an issue this investigation could answer.