PUBLIC HEALTH ASSESSMENT
METACHEM PRODUCTS, LLC
(a/k/a STANDARD CHLORINE OF DELAWARE, INCORPORATED)
NEW CASTLE, NEW CASTLE COUNTY, DELAWARE
The Agency for Toxic Substances and Disease Registry (ATSDR) conducted an evaluation of the Metachem Products site in New Castle, Delaware, in response to public health concerns expressed by a representative of a citizens group in the area. A spokesperson for the group "Stop Metachem Products LLC" expressed concerns about whether people in the area were being exposed to chemicals from the Metachem Products plant. A previous evaluation of the site, when the plant and property was owned by Standard Chlorine of Delaware, was issued on March 16, 1989 (1). Metachem purchased the facility from Standard Chlorine in 1998.
ATSDR has prepared an updated public health assessment because (1) new concerns have been raised by people in the community and (2) additional data are now available. This health assessment examines data on two major spills that occurred at the site during the 1980s and potential public health issues associated with the manufacturing of chlorobenzene products.
The Metachem site is 3 miles northwest of Delaware City, Delaware. The site is approximately 46 acres in size and is located near the south bank of Red Lion Creek. In 1965, Standard Chlorine of Delaware, Incorporated, built a chemical plant on what was then farmland. The site is in the northwest portion of a large industrial area that is bordered on the north by Red Lion Creek, on the east by the Delaware River, and on the south and west by farmland. Among the companies in the area are the Motiva Refinery (also known as Getty Refining and Star Enterprises); ICI Americas; Stauffer Chemical Company; American Mirrex; Zeneca, Incorporated; Occidental Chemical (formerly Diamond Shamrock Company, also known as OxyChem); and Air Products and Chemicals, Incorporated. Most, if not all, of the companies in the area have wells for drinking water, industrial process water, and/or groundwater monitoring (2-4).
On the north side of the site on the other side
of Red Lion Creek, there are farms and 46
residences within a 1-mile radius of the
Metachem site (see Figure 1). A few more
residences are within a 2-mile radius to the north, south, and west of the site. Delaware City,
approximately 3 miles southeast of the site, is the closest city (2, 4, 5).
Standard Chlorine operations started in 1966 with the production of chlorinated benzene compounds, including chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, and lesser amounts of 1,3-dichlorobenzene and trichlorobenzene. Although operations have varied over the years, these chemicals were still the primary products produced at the facility by Metachem until recently (2, 6).
In September 1981, a release of approximately 5,000 gallons of chlorobenzene occurred at the
Standard Chlorine Site while workers were filling a railroad tank car. Some of the chemical ran
off in surface ditches at the northwest and
southwest corners of the plant (see Figure 2) and
entered a tributary of the Red Lion Creek. In
response to the spill, the company took measures
to prevent the discharge from reaching the Red
Lion Creek. Under the direction of the Delaware
Department of Natural Resources and Environmental Control (DNREC), Standard Chlorine
conducted a groundwater investigation and found that the groundwater beneath the site was
contaminated with other chlorinated benzene compounds, in addition to chlorobenzene. The
primary source for the other chlorinated benzenes found was believed to be a process drainage
catch basin that leaked before it was repaired in 1976 (2).
Standard Chlorine installed a groundwater recovery and treatment system in 1982. This system was upgraded over time, and in 1986 the current groundwater recovery and treatment system was installed. The recovery wells are supposed to pump water from the shallow aquifer to control plume migration and prevent contamination of the deeper Potomac Aquifer, which is a source for drinking water in the area. However, the system has not been operated continuously. Standard Chlorine and Metachem monitored the groundwater recovery and treatment system, and the monitoring has been documented in quarterly reports to the U.S. Environmental Protection Agency (EPA), Region III, and DNREC since 1988 (2, 7). These reports document that the wells were seldom pumped in 2001 and during the first part of 2002. The system is still not operating continuously. EPA is evaluating the effectiveness of the system and what upgrades are needed.
The second major release at the Standard
Chlorine facility occurred on January 5, 1986.
Approximately 400,000 gallons of 1,4-dichlorobenzene and about 169,000 gallons of
trichlorobenzene were released when a 375,000
gallon tank split open. The tank collapsed and damaged three nearby tanks, causing those tanks
to spill some of their contents. The spilled chemicals flowed across the plant property and off the
site to an unnamed tributary to Red Lion Creek (see Figure 2). The tributary is to the west of the
facility. Some of the contaminants migrated from the mouth of the tributary along the southern
shoreline of Red Lion Creek. In response to the 1986 spill, DNREC and Standard Chlorine took
the following emergency actions: (1) booms, dikes, and a filter fence along the mouth of the
wetland coves were used to contain and minimize further discharge; (2) some of the material that
had flowed off the site was recovered; (3) pre-excavation sampling was conducted and an earthen
dike was constructed to isolate the upper portions of the wetland from contaminants; (4)
contaminated soil and sediment upstream of the dike was excavated; and (5) a double-lined
containment pond was constructed to store dredged materials (2, 7).
The Standard Chlorine site was proposed to the
U.S. Environmental Protection Agency's 
National
Priorities List for Uncontrolled Hazardous
Substances (NPL) on September 18, 1985. The site
was formally added to the NPL on July 1, 1987, making the site a "Superfund site" for which the
EPA had authority to oversee clean-up activities. Metachem Products bought the facility from
Standard Chlorine of Delaware in 1998. As part of the purchase agreement, Metachem assumed
liability for the Superfund clean-up requirements that might be required at the site by EPA (2).
In
December 1999, Metachem officials discovered that the waste benzene recycling
unit was exceeding the state air permit limit of 11 pounds per day of benzene.
Metachem shut down the recycling unit and redesigned it. A company report estimated
the benzene output as 266 pounds per day. However, it is not known whether the
benzene emissions were as high as 266 pounds a day during the entire 3-year
operating life of the unit. The air permit required Standard Chlorine to test
the unit within 180 days of starting up the unit in 1996, but it was not tested
until 3 years later, after Metachem had purchased the facility. The recycling
unit was not operated continuously. Metachem staff said the recycling system
was operated sporadically during the second half of 1999–about 45 days
in all (8, 9).
Until recently, Metachem operated the
chlorobenzene manufacturing facility, which had
air and water discharge permits. In May 2002,
Metachem notified EPA and the state that it was closing the manufacturing operations and filing
for bankruptcy. Metachem removed materials from some of the processing equipment, but left
most of the chemicals and wastes on the site (6).
A remedial investigation/feasibility study for the site was completed in 1992. On March 9, 1995, EPA issued a Record of Decision for the Standard Chlorine site. The selected remedy for the site has two components: an interim action for groundwater and a final action for contaminated soil and sediment. The interim action for groundwater specified containment of groundwater to minimize the continued release of contaminants. It included the following requirements:
The record of decision designated the preferred final action for soil and sediment to be biological treatment. Standard Chlorine was supposed to bioremediate the soil and sediment along the western drainage gully, the eastern drainage ditch, the area adjacent to Catch Basin 1, along the railroad tracks, and along the unnamed tributary to Red Lion Creek. In addition, Standard Chlorine was to bioremediate the soil in the waste piles and in the sedimentation basin using in situ (in place) or ex situ (excavated) treatment. If it was determined that bioremediation would not be feasible for the site (based on the results of treatability studies or further testing) the record of decision designated a preferred contingency remedy: low temperature thermal desorption (2).
Over the years, EPA Region III and DNREC
have received numerous complaints about odors
and air emissions from the Metachem facility
from an individual who lives in Newark,
Delaware, which is approximately 10 miles west of the site. The resident formed a citizens
group, the Coalition to Stop Metachem's Polluting, and became its spokesperson. An August 22,
2000, memorandum from the EPA Office of Inspector General summarizes the various
complaints and issues raised by the Coalition and discusses the investigations and actions taken
by EPA to address the complaints (10). In July 2000, the EPA Office of Inspector General's
engineering and science staff evaluated Metachem's chlorobenzene manufacturing process to
determine "...the potential for the chlorobenzene process to 'poison' the surrounding community
(especially in regards to chlorinated dioxins)..."(11).
One allegation the engineering and science staff investigated was whether the chlorobenzene
emissions from the manufacturing process could be converted by sunlight into dioxins and
furans. The staff found that the chemical literature indicates that sunlight degrades
chlorobenzenes into hydrocarbons and hydrochloric acid. Regarding the production of dioxins
during the manufacturing process, the staff found that the feedstock for the hydrogenation
process contains dioxins (one feedstock sample had 79 parts per trillion (ppt) of 2,3,7,8-tetrachlorodibenzo-p-dioxin), but that conditions in the hydrogenation process are not favorable
for the generation of additional dioxins. However, the conditions in the reactor will also not
destroy dioxin that may be entrained in the feed stock. More importantly, the hydrogenation
reactor is designed to dechlorinate
polychlorinated-benzene rings and will also
probably dechlorinate the more chlorinated
dioxin/furan congeners into the lower
chlorinated dioxin/furan congeners (for example, pentachloro- to tetrachloro- and hexachloro- to
pentachloro-, and so on), a process that could increase the toxicity of the dioxin mixture. The
staff concluded, "Air emissions of dioxin/furans are an insignificant pathway since the chemical
properties of dioxin/furans do not favor their partition into the vapor phase. Therefore, the only
significant source for the release of dioxin/furans from the Metachem facility are the small
amount of dioxin/furans that are potentially entrained in the chlorobenzene products. Since these
chlorobenzene products are used as intermediates whose final products are distributed nationally,
the local community should not be affected" (11).
As mentioned earlier, Metachem filed for bankruptcy in May of 2002. The facility is now under the control of EPA and DNREC. They are currently inventorying the chemicals on the site, stabilizing the facility, analyzing and consolidating chemicals, removing all the liquid products from the facility, cleaning and decontaminating the facility (tanks, pipes, equipment, and concrete structures), operating the waste water treatment facility, and providing site security (6,12).
ATSDR first became involved with the site when the Standard Chlorine Site was listed as an NPL site in 1987. The agency prepared a draft preliminary public health assessment and released it for public comment August 16, 1988 (13). The Preliminary Health Assessment for Standard Chlorine Company, Delaware City, New Castle County, Delaware was issued as a final document March 16, 1989 (1). ATSDR concluded that the site posed a potential public health threat to on-site employees and remedial workers through direct contact with the soil. In addition, ATSDR concluded that area residents who use surface waters in the area for swimming and fishing may be at increased risk of possible adverse health risks through direct contact with the water and through ingestion of fish that bioaccumulate site-related contaminants. ATSDR recommended that future site investigations include (1) characterization of the site and impacted off-site areas to evaluate the potential human exposure pathways and (2) a characterization of the hydrogeology of the area (1).
In June 2001, ATSDR received several letters from the spokesperson for the Stop Metachem Products LLC (previously the Coalition to Stop Metachem's Polluting) asking the agency to look into the Metachem Superfund Site. In a July 3, 2001, letter, ATSDR notified the spokesperson (hereafter referred to as the petitioner) that the agency would consider her letters to be a petition for a public health assessment. The agency agreed to review the health concerns described in the petitioner's letters, review any new information about the Standard Chlorine/Metachem site, and determine whether an update of the public health assessment was indicated (14). ATSDR staff have reviewed information available since the preliminary health assessment was published and prepared this updated public health assessment to address site conditions and community concerns.
ATSDR staff began working on this site in May 2002 and reviewing available information. On May 22, 2002, an ATSDR Region III representative met with EPA staff to learn about on-going site activities and future plans for the site and tour the Metachem site and surrounding area. She participated in several conference calls with EPA and DNREC regarding Metachem's closure and site activities. On June 13 she attended the EPA/DNREC public meeting to hear concerns expressed by community members. When driving around the area, she saw a couple of people fishing in Red Lion Creek off Route 9, just downstream from the Metachem site. It is not known if they were catching and releasing or keeping and eating any fish or other edible marine life they caught. There are no residences near the facility, the plant area is fenced, and DNREC is providing security for the site, so that public access or trespassing is not likely. There is a ball field on the east side of Metachem. The grass on the ball field was high, but it was being mowed the day that ATSDR staff visited the site. The ball field is owned by Occidental Chemical–it is not a publicly owned park.
The initial public health assessment was released for public review and comment December 23, 2002 (15). That document contained site information and data available through mid-November 2002. The first comment period ended January 31, 2003. Comments were received from two community members.
ATSDR staff tried to visit the site and meet with concerned residents a couple of times during the winter, but they had to cancel the travel because of bad snow storms. On March 12, 2003, staff toured the Metachem site and met with EPA, DNREC, and some of their contractors at the site. From noon to 1:30 pm, ATSDR staff met with several residents and members of the press at the Delaware City Fire Hall. A second day of meetings was scheduled for May 1, 2003, at the Gunning Bedford Middle School cafeteria. Two public availability sessions were held from 3:00-4:30 pm and 7:00-9:00 pm. A press briefing was planned for 4:30-5:00 pm, but no press showed up. The public comment period was extended until May 16, 2003. All comments related to the potential health effects caused by the Metachem facility that were received in writing or discussed by attendees with ATSDR staff at any of the meetings are summarized in Appendix C. ATSDR's response to each of the comments is provided after each comment.
On May 1, 2003, while driving around the areas within a couple of miles of the site, ATSDR staff observed an elderly gentleman fishing from the Red Lion Creek bank where highway 9 crosses the creek. The staff stopped and advised the man that he should not eat any fish caught in the creek or in the Delaware River. So far, he had not caught any fish. ATSDR staff noticed that the sign warning against eating fish caught in the creek was very weathered and not very legible, and the staff recommended to state personnel that a new sign be placed at that location. A new sign has been posted.
This public health assessment addresses health issues related to public exposure that may have occurred during the operating life of the Standard Chlorine and Metachem facility, that may currently be occurring, or that might occur in the future. This assessment evaluates the potential pathways by which the public might be exposed to chemicals from the site, including the exposures about which the community has expressed concerns. A separate section will discuss each of the ways (pathways) that persons could be exposed to chemicals from Metachem: by inhaling the chemicals in the air (inhalation pathway), by getting the chemicals on their skin (dermal pathway) from contact with contaminated soil, sediment, or surface water, and by eating or drinking food or ground water that is contaminated (ingestion pathway). Each pathway section will discuss the potential for exposure in the past, as well as whether exposure is currently occurring.
Table 1 provides a summary of the pathways by which residents, employees, or workers near Metachem could be exposed to chemicals at concentrations that could cause adverse health effects in the past, currently, or in the future.
Table 1. Exposure Pathways at the Metachem Site
|
Time Frame |
Who |
Inhalation | Dermal | Ingestion |
| Past | Residents | Not exposed | Not exposed | Not exposed if fish advisory was obeyed. |
| Workers* | Probably exposed | Probably exposed | Potential exposure before wells closed. | |
| Present | Residents | Not exposed | Not exposed | Not exposed if fish advisory is obeyed. |
| Workers* | Potentially exposed if PPE not worn | Potentially exposed if PPE not worn | Not exposed | |
| Future† | Residents | No exposure | No exposure | No exposure if fish advisory is obeyed and drinking water wells are not allowed in the contaminated areas of the Columbia aquifer. |
| Workers* | No exposure | No exposure | No exposure | |
| * Employees at Standard Chlorine, Metachem,
and nearby companies and remediation workers. † After site is remediated--assuming site remains an industrial facility with deed restrictions. PPE = Personal protection equipment |
||||
The community is concerned that the manufacturing process generated dioxins that were released into the air along with the chlorinated benzene products manufactured at the facility. The petitioner specifically mentioned concerns about air releases of the following chemicals: 2,3,7,8-dioxins, dioxins, benzene, 1,3-dichlorobenzene, paradichlorobenzene, and chlorobenzene. Some residents believe releases from the facility have caused public exposure at levels that caused health effects. Health effects mentioned were cancer (ovarian, liver, kidney, breast, cervical, leukemia, and bone), diabetes, autism, high blood pressure, and obesity. Community members also expressed concern that crops grown near the plant might be contaminated with dioxins.
Inhalation Pathway (Air Issues)
The EPA and DNREC Division of Air and Waste Management Web sites contain a significant quantity of data related to the Metachem site and New Castle County, where the facility is located and the petitioner resides.
ATSDR obtained from the EPA Web page an AIRData report containing data extracted from the June 2000 version of EPA's National Toxics Inventory database of hazardous air pollutant (HAP) emissions for 1996. According to this report, Standard Chlorine of Delaware released 68,271 total pounds of HAPs into the air in 1996. While this sounds like a lot of air pollution, it was 1.17% of all point source air emissions in Delaware. Industries in Delaware released a total of 5,851,291 pounds of HAPs that year. Table 2 shows the hazardous air pollutants released by Standard Chlorine in 1996 (16).
Table 2. Site Pollutant Emissions in 1996 (16)
| Pollutant | Emissions (pounds per year) |
| 1,2,4-Trichlorobenzene | 9,525.0 |
| 1,4-Dichlorobenzene | 26,190.0 |
| Benzene | 12.4 |
| Chlorobenzene | 30,035.0 |
| Hydrochloric Acid | 2,509.0 |
| Total | 68,271.4 |
To put these emissions in perspective, it is helpful to review the statewide peak ozone season daily emissions provided by the DNREC Division of Air and Waste Management for 1996, as shown in Table 3 (17). Note that the site emissions in Table 2 are in pounds per year and the quantities in Table 3 are given in tons per day.
Volatile organic compounds (VOCs) are the primary contributors to the formation of ozone. The peak ozone season is the summer, so that Delaware conducts air sampling for VOCs, nitrogen oxide compounds (NOx), and carbon monoxide (CO) from June 1 to August 31 (see Table 3). The Point Sources category listed in Table 3 includes facilities such as power plants, chemical manufacturing plants, refineries, auto assembly plants, solid waste landfills, and large building heating systems that have stacks or vents. Metachem is in the point source category. Tables 2 and 3 clearly show that Metachem's VOC emissions are a very small percentage (less than 0.3%) of the daily VOC emissions in the state of Delaware during the summer.
Table 3. 1996 Statewide Peak Ozone Season Daily Emissions (17)
| Source Category | Pollutant Emissions in Tons Per Day (TPD) | |||||
| VOC (TPD) | % VOC | NOx TPD | % NOx | CO (TPD) | % CO | |
| Point | 31 .728 | 8% | 78.799 | 42% | 90.655 | 17% |
| Stationary Area | 40.508 | 11% | 6.852 | 4% | 8.236 | 2% |
| Mobile | 71.321 | 19% | 94.219 | 49% | 447.737 | 81% |
| Biogenics | 241.941 | 62% | 9.228 | 5% | 0.000 | 0% |
| Total | 385.498 | 100% | 189.098 | 100% | 546.628 | 100% |
| VOC = volatile organic compound NOx = nitrogen oxide compounds CO = carbon monoxide % = percent |
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Stationary or Area Sources include sources such as dry cleaners, auto shops, gas stations, print shops, painting operations, degreasing and other solvent-using operations, small building heating systems, and other small businesses that may each emit small quantities of VOCs or CO. Added together, the VOC emissions from these sources are greater than those from larger industrial plants, and those emissions contribute significantly to the formation of ozone.
The Mobile Source category includes automobiles, trucks, motorcycles, ships, recreational boats, trains, airplanes (commercial, military, and private), tractors and other farm equipment, engines on construction equipment, and such items as lawn mowers, chain saws, and leaf blowers. Most engines in this category have no emission controls and are considered high emitters of VOCs.
Biogenic Sources include emissions from plant life in the area, such as crops, trees, grasses, and other vegetation. While biogenic sources emit significant quantities of VOCs into the atmosphere that may contribute to ozone formation, they also remove significant amounts of CO, sulphur dioxide, NOx, ozone, and particulate matter from the air and also cool the air, thus reducing pollution from other sources (17).
According to the EPA 1999 Toxics Release
Inventory report for Delaware, Metachem
released 106,159 pounds of reportable
chemicals, which was 1.28% of the total on-site releases (to air, water, and land) in the
state in 1999 (see Table 4).
Table 4. 1999 Toxics Release Inventory for Delaware (18)
| Facility City, County |
Total On-site Releases (pounds) | Percent of State's Releases |
| Indian River Power Plant Millsboro, Sussex |
2,292,925 | 27 .57 |
| Edge Moor/Hay Rd. Power Plants Wilmington, New Castle |
1,131,512 | 13.61 |
| Motiva Refinery Delaware City, New Castle |
1,020,663 | 12.27 |
| Du Pont Seaford Plant Seaford, Sussex |
734,490 | 8.83 |
| Georgetown Processing Plant #17 Georgetown, Sussex |
653,017 | 7.85 |
| DaimlerChrysler Co. Assembly Plant Wilmington, New Castle |
542,190 | 6.52 |
| GMC Nao Assembly Plant Wilmington, New Castle |
412,206 | 4.96 |
| Townsends, Inc. Millsboro, Sussex |
278,550 | 3.35 |
| Du Pont Edgemoor Plant Edgemoor, New Castle |
263,616 | 3.17 |
| NRG Energy Center Dover, Kent |
170,304 | 2.05 |
| Formosa Plastics Corp. Delaware City, New Castle |
151,895 | 1.83 |
| Metachem Products, LLC New Castle, New Castle |
106,159 | 1.28 |
| Rodel Inc. Newark, New Castle |
95,284 | 1.15 |
| Subtotal of top 13 companies | 7,852,811 | 94.43 |
| Delaware Total | 8,316,318 | 100.00 |
When we consider all the industries in the New Jersey, Baltimore, and Philadelphia areas that also contribute to the air pollution in Delaware, it is not surprising that local residents can smell chemicals when they are outdoors. Hydrogen chloride is the only chemical in the top ten chemicals released in the state in 1999 that was also released by Metachem (18).
If millions of pounds of chemicals are released into the air in Delaware each year, to what levels of chemicals are the public being exposed?
There are three air monitoring stations in New Castle County where DNREC collects samples and analyzes them for VOCs. These stations are the MLK monitoring station in Wilmington, northwest of the site (17), an air sampling station at the William Bubby Sadler ball field on Wrangle Hill Road southeast of the industrial area (19), and an air monitoring station at Lums Pond State Park (20). The ball field is about one mile southeast of Metachem, halfway between the industrial park and Delaware City. Table 5 presents a summary of results of air data from the stations at Wilmington and the Delaware City ball field for 2000 and 2001. Table 6 presents a summary of the 2002 air data from all three air monitoring stations. When the air concentrations in 2000-2002 (shown in Tables 5 and 6) are compared to health values for the chemicals that may be related to emissions from Metachem (in Table 12), one can tell that the off-site concentrations of these chemicals that the public is exposed to are below levels that would cause health effects.
The Delaware Annual Air Quality Report–2000 also provided charts of the annual averages of eight VOCs monitored at the Wilmington MLK air station from 1991 to 2000 (see Figure 3). Before 1996, the concentrations of all eight chemicals were substantially higher than the concentrations detected in 2000. Most of the chemical concentrations in air have steadily declined since 1996 (17).
The DNREC air monitoring stations do not collect samples for dioxin compounds, a class of
chemicals the community is particularly concerned about. In September 2002, EPA collected
eight air samples out-of-doors at the Metachem site and analyzed them for dioxins and furans.
The dioxin toxicity equivalent (TEQ) concentrations in the on-site air samples ranged from 0.025
to 0.133 pg/m3. An indoor air sample recently taken in the Metachem warehouse contained 0.49
pg/m3 dioxin TEQ (20). In November 2002, the four air samples EPA took at the site perimeter
ranged in dioxin concentrations from
0.02 to 0.04 pg/m3 TEQ. All of these
on-site concentrations are below
concentrations that are expected to
cause adverse health effects. If one
assumes that the Metachem facility is
the source of the dioxins that were
measured in the outdoor air samples, then concentrations at the closest residence would be many
times lower and probably not detectable. Public health effects are not expected from exposure to
such low concentrations of dioxin compounds.
All of the air data reviewed by ATSDR staff indicate that the off-site concentrations of the organic chemicals that could have been released from the Metachem site are not currently (or in the last four years) at levels likely to cause adverse health effects in the general population of New Castle County. While the general public is not expected to be exposed to chemicals from Metachem by the air pathway, this may not be true in the past for on-site workers or for employees of companies nearby. During the two major spills and their cleanup and during the operation of the waste recycling unit from 1996 to 1999, workers in the area around the site may have been exposed by the air pathway to levels of benzene and chlorinated benzene products above health-based screening values. Because the concentration of chemicals that workers were potentially exposed to is not known, this health assessment discusses the toxicology of the chemicals known to be released from the Metachem site (see the section on the Toxicity of Site-Related Chemicals).
EPA hired Battelle Memorial Institute in Columbus, Ohio, to evaluate several different air sampling methods to determine their usefulness in monitoring air concentrations of chemicals at Superfund sites. The various sampling methods were used to take air samples at five Superfund sites in Delaware July 24 to August 9, 1989. One of the sites used in the study was Standard Chlorine, Inc. and the large industrial complex where the facility is located (21, 22).
Samples were taken at the fence lines of Standard Chlorine (now called Metachem) and the Star Enterprises' (now called Motiva) oil storage facility. Samples were also taken by several other sampling methods in the communities near the site. The community sampling locations were the William Bubby Sadler ball field about 1 mile southeast of the industrial complex and two locations 2-3 miles north-northeast of the complex. The locations of the northern samples were at a DNREC monitoring station adjacent to Highway 9 about 2 miles northeast of the complex, and in the backyard of a residence in Llangollen Estates approximately 3 miles north of Standard Chlorine.
Table 7 contains the data for the fence line samples taken at Metachem and Motiva and the average of the samples taken in the community. The fence line samples were collected "only when there were indications that an 'event' was occurring, such as smells, data from real-time instrumentation or obvious plumes."(22) The fence line data, therefore, provide some information on concentrations of chemicals to which on-site workers were typically exposed in the late 1980s. The report and articles published about the Delaware study do not give the concentrations measured at the Llangollen Estates location; they say only that "the concentrations at the sites 1-3 miles away from specific sources are essentially at background levels, generally not exceeding 2 ppb."(22) The average air concentrations for chemicals related to the Metachem site are all less than 1 ppb at the other air monitoring stations (see Table 7).
A comparison of the fence line air concentrations of the Metachem chemicals in Table 7 to the inhalation health comparison values in Table 12 indicates that none of the chemicals are likely to cause adverse health effects in workers or the community.
Table 5. Air Toxics Summary Data from MLK Monitoring Station (Wilmington) for the Year 2000 and from the Ball Field Monitoring Station (Delaware City) for the Year 2001 (17, 19)
| Compound in parts per billion (ppb) | Wilmington Monitoring Station (ppb) | Delaware City Monitoring Station (ppb) | ||||
| Average | Maximum | Minimum | Average | Maximum | Minimum | |
| Dichlorodifluoromethane | 0.63 | 1.27 | 0.48 | 0.57 | 1.04 | 0.29 |
| Chloromethane | 0.56 | 0.84 | 0.42 | 0.66 | 3.63 | 0.17 |
| 1,2-Dichloro-1,1,2,2-tetrafluoroethane | 0.02 | 0.04 | 0.01 | 0.02 | 0.04 | ND |
| Chloroethene | 0.02 | 0.22 | 0.00 | 0.35 | 1.56 | 0.01 |
| 1,3-Butadiene | 0.12 | 0.37 | 0.00 | 0.08 | 0.27 | 0.00 |
| Bromomethane | 0.05 | 1.20 | 0.01 | 0.02 | 0.14 | 0.00 |
| Chloroethane | 0.02 | 0.08 | 0.01 | 0.02 | 0.20 | 0.00 |
| Trichloroflluoromethane | 0.32 | 0.50 | 0.25 | 0.32 | 0.59 | 0.11 |
| 1,1-Dichloroethene | 0.00 | 0.01 | 0.00 | 0.00 | 0.04 | ND |
| Methylene chloride | 0.40 | 1.71 | 0.09 | 0.12 | 0.35 | 0.04 |
| 1,1,2-Trichloro-1,2,3-trifluoroethane | 0.10 | 0.19 | 0.08 | 0.09 | 0.14 | 0.07 |
| 1,1-Dichloroethane | 0.00 | 0.01 | 0.00 | 0.00 | 0.01 | ND |
| cis-1,2-Dichloroethene | 0.00 | 0.01 | 0.00 | 0.00 | 0.01 | ND |
| Chloroform | 0.04 | 0.09 | 0.02 | 0.02 | 0.05 | 0.01 |
| 1,2-Dichloroethane | 0.01 | 0.02 | 0.00 | 0.02 | 0.07 | 0.00 |
| 1,1,1-Trichloroethane | 0.07 | 0.11 | 0.05 | 0.05 | 0.08 | 0.03 |
| Benzene | 0.55 | 1.41 | 0.23 | 0.49 | 1.64 | 0.15 |
| Carbon tetrachloride | 0.11 | 0.16 | 0.09 | 0.10 | 0.15 | 0.08 |
| 1,2-Dichloropropane | 0.00 | 0.01 | 0.00 | 0.00 | 0.01 | ND |
| Trichloroethene | 0.11 | 2.35 | 0.01 | 0.14 | 3.21 | ND |
| cis-1,3-Dichloropropene | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | ND |
| trans-1,3-Dichloropropene | 0.00 | 0.01 | 0.00 | 0.00 | 0.00 | ND |
| 1,1,2-Trichloroethane | 0.00 | 0.01 | 0.00 | 0.00 | 0.00 | ND |
| Toluene | 1.27 | 5.31 | 0.46 | 0.75 | 2.92 | 0.23 |
| 1,2-Dibromoethane | 0.00 | 0.01 | 0.00 | 0.00 | 0.00 | ND |
| Tetrachloroethene | 0.12 | 0.47 | 0.02 | 0.03 | 0.13 | 0.01 |
| Chlorobenzene | 0.01 | 0.10 | 0.00 | 0.06 | 0.35 | 0.00 |
| Ethylbenzene | 0.18 | 0.53 | 0.06 | 0.09 | 0.71 | 0.02 |
| meta & para-Xylene | 0.60 | 3.76 | 0.21 | 0.29 | 2.51 | 0.05 |
| Styrene | 0.05 | 0.25 | 0.01 | 0.02 | 0.04 | 0.00 |
| 1,1,2,2-Tetrachloroethane | 0.00 | 0.02 | 0.00 | 0.00 | 0.00 | ND |
| ortho-Xylene | 0.23 | 0.66 | 0.08 | 0.10 | 0.91 | 0.02 |
| 1-Ethyl-4-methylbenzene | 0.05 | 0.19 | 0.01 | 0.02 | 0.18 | 0.00 |
| 1,3,5-Trimethylbenzene | 0.08 | 0.30 | 0.02 | 0.03 | 0.18 | 0.00 |
| 1,2,4-Trimethylbenzene | 0.21 | 0.76 | 0.06 | 0.09 | 0.55 | 0.01 |
| Chloromethylbenzene/Benzyl chloride | 0.00 | 0.01 | 0.00 | 0.00 | 0.01 | 0.00 |
| 1,3-Dichlorobenzene | 0.01 | 0.04 | 0.00 | 0.01 | 0.03 | 0.00 |
| 1,4-Dichlorobenzene | 0.04 | 0.11 | 0.01 | 0.08 | 0.47 | 0.00 |
| 1,2-Dichlorobenzene | 0.01 | 0.06 | 0.00 | 0.05 | 0.34 | 0.00 |
| 1,2,4-Trichlorobenzene | 0.00 | 0.01 | 0.00 | 0.01 | 0.04 | 0.00 |
| Hexachloro-1,3-butadiene | 0.00 | 0.01 | 0.00 | 0.00 | 0.00 | ND |
Table 6. 2002 Air Toxics Summary Data from
the MLK-Wilmington, the Ball Field in Delaware City, and Lums Pond Monitoring
Stations (23)
| Compound in parts per billion (ppb) | Wilmington Monitoring Station | Delaware City Monitoring Station | Lums Pond Monitoring Station | |||
| Maximum ppb | Average ppb | Maximum ppb | Average ppb | Maximum ppb | Average ppb | |
| Benzene | 0 .83 | 0.36 | 2.17 | 0.35 | 0.75 | 0.18 |
| Chlorobenzene | 0.02 | 0.00 | 0.27 | 0.02 | 0.02 | 0.00 |
| 1,3-Dichlorobenzene | 0.00 | 0.00 | 0.04 | 0.00 | 0.01 | 0.00 |
| 1,4-Dichlorobenzene | 0.05 | 0.02 | 0.18 | 0.02 | 0.08 | 0.01 |
| 1,2-Dichlorobenzene | 0.01 | 0.00 | 0.22 | 0.01 | 0.01 | 0.00 |
| 1,2,4-Trichlorobenzene | 0.00 | 0.00 | 0.04 | 0.00 | 0.00 | 0.00 |
Table 7. Battelle Delaware Air Study for
EPA in 1989 (21, 22)
| Compound in parts per billion (ppb) | Fence line Data (10 samples) Standard Chlorine (ppb) | Fence line Data (2 samples) Texaco/Motiva (ppb) | Average Concentrations at 2 Monitoring Stations (ppb) |
| Dichloromethane | 1-12 | NA | 0.99 |
| Benzene | 1-51 | NA | 0.58 |
| Chlorobenzene | 7-260 | NA | 0.25 |
| p-Dichlorobenzene | 12-247 | NA | 0.61 |
| o-Dichlorobenzene | 4-154 | NA | 0.13 |
| Trichlorobenzene | 1-41 | NA | 0.04 |
| Butane | NA | 22-103 | 2.22 |
| Isopentane | NA | 13-444 | 2.37 |
| Pentane | NA | 7-200 | 1.05 |
| 2-Methylpentane | NA | 2-50 | 0.53 |
| 3-Methylpentane | NA | 2-25 | 0.37 |
| Methylcyclopentane | NA | 1-13 | 0.17 |
| NA = not available (samples at this location
not analyzed for this chemical) ppb = parts per billion |
|||
Dermal Pathway (Soil, Sediment, Surface Water, Products, and Waste Issues)
Metachem employees and remediation workers may come in contact with on-site and off-site soil
and sediment that are contaminated from process leaks and the two major spills that occurred at
the site. Because there are no residences near the northwest portion of the industrial area and
there are marshes along the banks of the
Red Lion Creek and its tributaries, it is
highly unlikely that the public will
come into contact with the
contaminated soil and sediment.
Boating or other recreational uses of Red Lion Creek downstream of the site may result in brief,
intermittent exposure to contaminated surface water. Because of the existence of the marshes
along the banks of Red Lion Creek, swimming and other activities that would result in longer
dermal exposure to the surface water and sediments are not considered likely.
Employees of the companies adjacent to Metachem (Air Products to the west and OxyChem to
the east) may come into contact with off-site soil and sediment contaminated by
chemicals from Metachem if they
wander through the unfenced area north
of the Metachem plant or along the
unnamed tributary west of Air Products
and Metachem. According to ATSDR
staff members' observations during site visits, it is very unlikely that employees of other
industries in the area would trespass or wander onto Metachem's unfenced property because of
the dense thickets of briars and other vines and the marshes in that area of the site.
The two major spills ran primarily in drainage ditches to the west into the unnamed tributary of
Red Lion Creek. During the 1986 spill, however, materials also flowed across the site to the
eastern drainage ditch and northward to the unnamed tributary (see Figure 2). Employees said
that in a loading dock area on site the chemicals were about four feet deep. According to the EPA
Record of Decision, the concentrations of total chlorinated benzene compounds in on-site surface
soils (inside the existing plant fence) range
from 1.2 milligrams per kilogram (mg/kg)
to 68,427 mg/kg (see Table 8). Typically,
the concentrations of chlorinated benzene
were much lower in the subsurface. The
concentrations of total chlorinated benzene
compounds in surface soils outside the existing plant fence and the concentrations of total
chlorinated benzene compounds in off-site sediments are shown in Table 8. More recent soil and
sediment samples taken during 2002 and 2003 generally contained lower concentrations of
chlorinated benzene compounds; however, the data clearly show that the site is contaminated and
continues to need remediation (24). Remediation workers should wear appropriate personal
protective equipment to prevent dermal exposure to highly contaminated equipment, soil, and
sediment both on and off the site.
From the data and figures ATSDR has reviewed, it appears that the OxyChem ball field to the east of the site was not contaminated by the spills from Metachem (2). Figure 5 shows an aerial view of the Metachem site and the ball field.
Table 8. Total Chlorinated Benzene Concentrations in Surface Soil and Sediment (2)
| Media | Minimum (mg/kg) | Maximum (mg/kg) | Mean (mg/kg) |
| On-site soils | 1.2 | 68,427 | 4,452 |
| Off-site soils | 1.0 | 87,691 | 3,742 |
| Off-site sediments | 0.5 | 178,228 | 4,199 |
| mg/kg = milligrams per kilogram On-site = within fenced plant Off-site = unfenced areas of the site |
|||
During the remedial investigation, low levels of chlorinated benzene compounds were detected in
surface water samples collected from Red Lion Creek and the unnamed tributary to Red Lion
Creek. The concentrations ranged from 10 to 360 micrograms per liter (2). The higher
concentrations were generally in samples collected from surface water in the unnamed tributary
where public exposure is very unlikely.
Recent surface water sampling data are not
available. Because the groundwater that
discharges to the tributary and creek is still
contaminated and the sediments have not
been remediated, the surface water is likely
to still contain low levels of chlorinated benzene compounds. Boating or other recreational use, if
any, of Red Lion Creek down stream from the site may result in brief, intermittent exposure to
surface water, but the chemical concentrations in Red Lion Creek are too low for dermal contact
with the water to be a health concern.
Metachem submitted a report to the State of Delaware, Dioxin and Furan Testing Data, dated March 29, 2001 (25), that contains all the dioxin and furan data that were in the Metachem files at that time. In 1996, a number of process samples were analyzed. Some process samples contained dioxins and furans, while samples from other parts of the process contained no detectable quantity of dioxins or furans; the same was true for the waste samples taken in 1996. The concentrations of dioxins and furans detected were extremely small. Results were reported in picograms per gram (pg/g) concentrations. In 2002 and 2003, EPA contractors sampled and analyzed soils, sediments, products, and waste products for dioxins and furans. Table 9 contains the EPA dioxin data. Because the manufacturing wastes are disposed of at a hazardous waste facility, the local community is not likely to be exposed to the wastes.
Table 9. EPA 2002 and 2003 Dioxin and PCB Data (24, 43)
| Media | Dioxin TEQ | PCB |
| On-site Soils (6-12 inches) | 0.5-23.1 ppb | <1.0-13.0 ppm |
| On-site Equipment | Boilers: 6.5-82.9 ppt Column area: 8-1844 ppb |
Column area: not detected |
| Products | 1-22 ppt | 0.09-37 ppm |
| Process Wastes | 6.5-20.5 ppb | 6.7-530 ppm |
| Unfenced Soils & Piles | 0.36-2.20 ppm | |
| Off-site Sediments | 0.2-1.3 ppb | 0.055-1.0 ppm |
| PCB = polychlorinated biphenyl ppb = parts per billion ppm = parts per million ppt = parts per trillion TEQ = toxicity equivalent |
||
The Metachem dioxin report also contained analytical data of dioxin concentrations in products manufactured by Metachem and other chlorobenzene manufacturers (25). Product data are included in this discussion in Table 10 because the two large spills that occurred in the 1980s contaminated both on-site and off-site soils, along with groundwater and portions of Red Lion Creek. The concentrations of dioxin-like compounds in the samples are extremely low and will not contribute significantly to the toxicity of the products or the contaminated soil, sediment, surface water, or groundwater. The toxicity of the chemical products themselves would be a greater health hazard. Because Metachem's process materials and products are used by other industrial and manufacturing companies–not sold directly to the public–the public is not likely to be exposed to the products or process materials. One exception is paradichlorobenzene, which other companies mold into moth balls, deodorizers, etc. that are then sold to the public chemically unchanged.
The waste water treatment effluent and the activated carbon from the waste water treatment plant were analyzed for dioxins and furans in 1999. The effluent had no detectable dioxins or furans. Using one-half the detection limits to calculate the toxicity equivalent (TEQ) yielded a dioxin TEQ of 0.0003 parts per billion (ppb) or 0.3 pg/g. The activated carbon contained detectable concentrations of some dioxin and furan congeners. Adding one-half the detection limit for nondetected congeners to the detected amounts, the calculated dioxin TEQ was 0.745 ppb or 745 pg/g for the activated carbon sample (25). The public is not exposed to the activated carbon, but the analytical data are included in this discussion because of the petitioner's interest in dioxin at the site. The report did not indicate how long the activated carbon had been in use when the sample was taken; therefore, it is not possible to estimate the amount of dioxin-like compounds removed on a daily or hourly basis–that is, what concentration of dioxins might be in the effluent during a malfunction of the activated carbon unit. The Metachem waste water treatment effluent is a permitted discharge to the Delaware River, but there is little potential for dermal exposure to the discharge during recreational use of the Delaware River because of rapid dilution in the large volume of water in the river.
Table 10. Dioxin Toxicity Equivalents (TEQ) in Chlorobenzene Products (25)
| Chemical Product | Date (mo/yr) |
TEQ (pg/g) |
TEQ Calculation for Nondetects Used | |
| Detection Limit | Zero | |||
| 1,2,4-Trichlorobenzene | 04/1994 | <1100 | X | |
| Chlorobenzene | 12/1986 | 0 | X | |
| Dichlorobenzene | 12/1986 | 50 | X | |
| Trichlorobenzene | 01/1987 | 201,300 | X | |
| 1,2,4-Trichlorobenzene | 06/1996 | 0 | X | |
| 1,2,3-Trichlorobenzene | 11/2000 | 0.83 | X (0.71 pg/g) | |
| 1,2,3-Trichlorobenzene | 11/2000 | 0.74 | X (0.74 pg/g) | |
| 1,2,3-Trichlorobenzene | 11/2000 | 0.80 | X (0.80 pg/g) | |
| 1,2,4-Trichlorobenzene | 12/2000 | 0.66 | X (0.66 pg/g) | |
| 1,2,3-Trichlorobenzene | 12/2000 | 1.75 | X (1.75 pg/g) | |
| 1,2,3-Trichlorobenzene | 12/2000 | 2.89 | X (2.89 pg/g) | |
| 1,2,3-Trichlorobenzene | 12/2000 | 1.22 | X (1.22 pg/g) | |
| mo/yr = month/year pg/g = picogram or 10-12 grams per gram = parts per trillion (ppt) |
||||
Ingestion Pathway (Groundwater and Food Chain Issues)
People have expressed concerns that they might be exposed to contaminants from Metachem by eating crops grown in the fields around the industrial area, by eating fish from Red Lion Creek and the Delaware River, and by drinking contaminated groundwater. This section examines the data available on the site-related chemicals present in each of these media.
The petitioner and local residents are
concerned about whether it is safe to eat
crops grown in the fields around the
industrial area where Metachem is
located. They question whether dioxin or chlorinated benzenes from Metachem have
accumulated in soil and in produce grown near the plant. ATSDR does not have data from the
analysis of crops grown in the area or soil samples taken from the fields where food crops are
grown. However, EPA Region III provided soil data taken in off-site areas around the plant to
identify the areas affected by the company and needing to be remediated. When one gets away
from the areas where spilled products exist, the soil concentration of total chlorinated benzenes
quickly falls below the detection limit of 0.5 mg/kg (2).
One would expect to find higher concentrations of settled airborne contaminants in undisturbed surface soil near the facility than in cultivated soil a half mile or more from the facility. Nearby soils could be affected by deposition from fugitive emissions as well as stack emissions. ATSDR considers that produce grown in the fields near the site present no public health hazard for two reasons. First, the surface soil near Metachem, except for the areas affected by the Metachem spills, does not present a health hazard. Second, farm practices, such as aeration, irrigation, and fertilization, are conducive to biodegradation of organic compounds (like chlorinated benzenes, if any are present), making it unlikely that organics from Metachem have accumulated in the soil or in the crops in farmland near the facility. Although ATSDR thinks that it is unlikely that Metachem contaminants have accumulated in the soil or crops in the farmland near the site, analyses of soil and crop samples from these areas could be conducted to provide a more definitive answer to this community concern.
Contaminants from the Metachem spills and
other industrial discharges have
bioaccumulated in edible marine life in Red
Lion Creek. In 2000-2001, an ecological risk
assessment was conducted for the Metachem
site. The assessment included analyzing
samples of fish collected from Red Lion Creek (26). The following types of fish were caught and
analyzed: mummichog, pumpkinseed, brown bullhead, and American eel. Table 11 lists only the
chemicals detected in the fish tissue samples.
A fish consumption advisory issued on May 2, 1986, by the Delaware Department of Natural Resources and Environmental Control (DNREC) and the Delaware Division of Public Health recommended that people not consume fish taken from Red Lion Creek downstream of Route 13. The state currently advises that individuals limit their consumption of fin fish caught in Red Lion Creek between Route 13 and the Delaware River to no more than three 8-ounce meals per year. The state also advises against eating any fin fish caught in the Delaware River (27). If people comply with the Delaware fish advisories, ATSDR does not expect any adverse health effects to result from eating fish caught near Metachem.
Table 11. Summary of Red Lion Creek Fish Tissue Analyses in 2000-2001 (26)
| Parameter | Mummichog | 5 Pumpkinseed | Brown Bullhead | 5 American Eel | |||
| mg/kg† | Min. | Max. | Min. | Max. | Min. | Max. | |
| 1,4-Dichlorobenzene | 1 .2* | 1.1 | 2.0 | 0.54 J | 1.5 J | 2.0 | 5.8 |
| 1,3-Dichlorobenzene | 0.45 J* | 0.22 J | O.42 J | 0.12 J | 0.26 J | 0.33 J | 0.9 |
| 1,2-Dichlorobenzene | 0.59 J* | 0.3 J | 0.51 J | 0.2 J | 0.36 J | 0.56 J | 1.6 |
| 1,2,4-Trichlorobenzene | 1.0* | 0.45 J | 0.7 | 0.32 J | 0.35 J | 0.49 J | 1.6 |
| 1,2,3-Trichlorobenzene | 0.56 J* | 0.26 J | 0.39 J | 0.2 J* | 0.27 J | 0.7 | |
| 1,2,4,5-Tetrachlorobenzene | 0.66 U* | 0.66 U | 0.67 U | 0.67 U* | 0.13 J | 0.93 J | |
| 1,2,3,4-Tetrachlorobenzene | 0.14 J* | 0.13 J | 0.16 J | 0.67 U* | 0.12 J | 0.41 J | |
| Pentachlorobenzene | 0.66 U* | 0.66 U | 0.67 U | 0.67 U* | 0.11 J | 0.67 U | |
| † All concentrations are in milligrams per
kilogram (mg/kg) J = Concentration estimated * Only one sample analyzed for this chemical U = Chemical not detected at this Bold font means concentration is above detection limit detection limit Min. = Minimum Max. = Maximum |
|||||||
The uppermost aquifer beneath Metachem is the Columbia aquifer. In most areas the depth to
groundwater in this aquifer ranges from 30 to 60 feet below ground surface. Some members of
the community commented that it is
shallower in some areas. The general
direction of groundwater flow in the
Columbia is to the north-northwest and north
toward the unnamed tributary and Red Lion
Creek. The Columbia aquifer beneath the site and northward to Red Lion Creek is very
contaminated with chemicals from process leaks and the two large spills at Metachem. There is a
layer of product in the groundwater in some areas under the site (2, 28). Figure 4 shows the plume of contaminants from Metachem as of September 2002.
Well permit data obtained from DNREC
show that there are a number of drinking
water wells within a mile of Metachem
that pump water from the Columbia
aquifer 30-40 feet below ground. However, industries near Metachem purchase drinking water
from the local utility and their production wells are about 130 feet deep in the Potomac aquifer,
which is not contaminated (2, 24, 25, and personal communication with staff members of
DNREC).
In December 2002 and January 2003, the Delaware Division of Public Health, Office of Drinking Water sampled the water from wells within a 1.5-mile radius of the Metachem facility. The samples were all collected from inside taps of homeowners, either a kitchen sink or a bathroom sink, or at a hand sink if the sample was collected from a business. The samples were not filtered prior to analysis. EPA Method 524.2 was used to analyze the samples for 62 volatile organic compounds (VOCs), which included chlorobenzene compounds (29, 30). Fourteen samples contained no VOC contaminants. Two samples had low levels of VOCs that were below drinking water standards and were unrelated to Metachem. One sample had 1.55 ppb 1,2-dichloroethane (DCA) and the other sample contained 71.89 ppb total trihalomethanes. The drinking water standard is 5 ppb and 80 ppb for DCA and trihalomethanes, respectively. The Delaware Division of Public Health concluded that "contaminants from the Metachem facility have not impacted the drinking water wells in the vicinity. Therefore, drinking from these wells does not expose individuals to increased health risk from volatile organic chemicals."(29)
Because no one is currently drinking
groundwater near the Metachem plume of
contamination, there is no current public
health hazard from the ingestion of
groundwater. Unless deed restrictions and
prohibition of the use of the Columbia aquifer for drinking water in the vicinity of Metachem are
enforced, however, public exposure to contaminated groundwater could occur in the future.
Since 1982, Standard Chlorine and then Metachem have intermittently pumped and treated the contaminated groundwater. Product recovered from the water was burned in the facility's boiler, and groundwater was treated in the waste water treatment plant. By the end of 2001, they had pumped a cumulative total of 470,179,000 gallons of groundwater and recovered a total of 141,834 kilograms of chlorinated benzene compounds (28). However, the groundwater is still very contaminated. EPA and DNREC are evaluating how to remediate the groundwater under the site.
Toxicity of Site-Related Chemicals
This section will discuss the predominant chemicals released from the Standard Chlorine and Metachem facility: chlorobenzene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene, hydrogen chloride, and benzene. The residents of New Castle County should not be concerned that they might have any of the health effects discussed in this section because it is unlikely that even during the spills that residents were exposed to any of these chemicals at levels that would cause health effects. The toxicity section is included because of the potential that workers at the facility, or near it, may have been exposed to significant concentrations of these chemicals during spills or other releases from the Metachem facility.
Chlorobenzene, also called monochlorobenzene, was one of the major products made at the facility. It was the one typically released in the largest quantity each year (according to Toxic Release Inventory data), and 5,000 gallons of it were released onto the ground in 1981 when workers were filling a railroad car. It is primarily used as a chemical intermediate in the manufacture of other products.
Chlorobenzene is a colorless, flammable liquid with an aromatic, almond-like odor. When released to the air, it is slowly broken down by reactions with other chemicals and sunlight or it can be removed by rain. In water, chlorobenzene will rapidly evaporate or be broken down by bacteria. When released to soil, it is broken down rapidly by bacteria, but some of the chlorobenzene will evaporate to the air and some may filter into the groundwater. It does not build up in the food chain (31).
In studies of workers exposed to high levels of chlorobenzene in the air, the workers complained of headaches, nausea, sleepiness, numbness, and vomiting. In studies of animals, central nervous system effects reported included unconsciousness, tremors, restlessness, and death. In studies of animals exposed for longer periods of time, liver and kidney damage was reported. The limited data available indicate that chlorobenzene does not cause birth defects or infertility (31).
It is not known whether chlorobenzene causes cancer in people. Although chlorobenzene did not produce cancer in animal studies conducted with rats and mice, liver nodules that can lead to cancer were produced in male rats. EPA has determined that chlorobenzene is not classifiable as to human carcinogenicity because there is inadequate evidence in studies of both humans and animals (31, 32).
There is very little information on how children react to chlorobenzene exposure, but children would probably show the same effects as adults. There is a report that a 2-year-old male who swallowed 5 to 10 cubic centimeters of chlorobenzene became unconscious, did not respond to skin stimuli, and had muscle spasms, but recovered uneventfully. There is no credible evidence that chlorobenzene causes birth defects (32).
1,4-Dichlorobenzene (also known as paradichlorobenzene) is a household chemical commonly called mothballs that is used to control moths, mold, and mildew and to deodorize restrooms and waste containers. At room temperature, it is a white solid that slowly changes to a vapor when exposed to air. It is the vapor that acts as a deodorizer and insect killer. Most people can smell it at very low levels and can recognize the smell as that of mothballs. On January 5, 1986, about 400,000 gallons of 1,4-dichlorobenzene was spilled at the site. In air, 1,4-dichlorobenzene breaks down to harmless products in about a month (33, 34). Table 12 provides additional information on this chemical. There is no evidence that moderate use of 1,4-dichlorobenzene will result in harmful health effects. Harmful effects, however, may occur from high exposures. Very high usage in the home can cause dizziness, headaches, and liver problems. There are cases of people who ate 1,4-dichlorobenzene products regularly for months to years. These people had adverse health effects, such as skin blotches and lower numbers of red blood cells (33, 34). People should not eat 1,4-dichlorobenzene.
There is no direct evidence that 1,4-dichlorobenzene can cause cancer in humans. However, in studies of animals given very high levels of the chemical in water, the animals developed liver and kidney tumors. Therefore, ATSDR considers that 1,4-dichlorobenzene may reasonably be anticipated to be a carcinogen. EPA classifies it as a Group C carcinogen, that is, a possible human carcinogen (33, 34).
Products that contain 1,4-dichlorobenzene should be stored out of the reach of young children. Children should not be allowed to play with mothballs (or other products containing 1,4-dichlorobenzene) or rub the materials on their skin. Adults in a household that use toilet deodorizers containing 1,4-dichlorobenzene should make sure that children do not drink water from the toilet bowl or play with the water. There is very little information on how children react to 1,4-dichlorobenzene exposure, but children would probably show the same effects as adults. There is no credible evidence that it causes birth defects (33, 34).
At room temperature, 1,2,4-Trichlorobenzene is a nonflammable, colorless liquid. It is used as a chemical intermediate, in septic tank and drain cleaners, as a solvent, and in dielectric fluids, cleaners, degreasers, and lubricants. It evaporates slowly when exposed to air, so that it is likely to stay in soil and water if it is released to the environment. It is persistent in the environment because it strongly adsorbs to soils. Trichlorobenzene is expected to bioaccumulate in aquatic organisms. Once in the air, it breaks down photochemically with an estimated half-life of approximately 18.8 days (35). In January 1986, about 169,000 gallons of trichlorobenzene were spilled during the tank collapse and release at Standard Chlorine.
Trichlorobenzene is readily absorbed when oral, inhalation, and dermal exposure occur. Direct contact with the chemical irritates the skin and may cause dermatitis. Its vapors irritate the eyes and respiratory tract. In studies of animals given high oral or dermal doses, tremors and convulsions, followed by death, occurred. Animal studies have also shown that trichlorobenzene can adversely affect the liver, kidneys, and the adrenal gland (35).
There is no direct evidence that 1,2,4-trichlorobenzene can cause cancer in humans. Large amounts of it in the diet of animals caused cancer in mice but not in rats. From this conflicting animal data it is not possible to determine the potential of trichlorobenzene to cause cancer in humans (35). Household products containing 1,2,4-trichlorobenzene should be kept out of the reach of children.
Hydrogen chloride is a colorless to slightly yellow, nonflammable gas with a sharp, irritating odor. When hydrogen chloride dissolves in water, it forms hydrochloric acid, also known as muriatic acid. Hydrochloric acid is a component of commercial chemicals used to clean and disinfect swimming pools and to clean mortar off bricks. It is also used in electroplating metals; in refining mineral ores; in leather tanning; in refining fats, soaps, and edible oils; and in manufacturing polymers, plastics, rubber, fertilizers, dyes, and chlorinated solvents (36).
Atmospheric moisture causes hydrogen chloride to form a dense white vapor when it comes in contact with air. The vapor is corrosive, and air concentrations above 5 parts per million (ppm) can cause irritation. Its odor and highly irritating properties generally provide adequate warning for acute, high-level exposures. However, at the permissible exposure limit of 5 ppm set by the Occupational Safety and Health Administration, only 50% of exposed persons can perceive hydrogen chloride's odor, so that smell alone may not provide adequate warning (36).
Both hydrogen chloride and hydrochloric acid are corrosive and can cause severe chemical burns on contact. Hydrogen chloride is not absorbed through the skin. Hydrogen chloride gas can irritate the lungs, causing a cough and shortness of breath. Breathing high levels of the gas or vapor can lead to a buildup of fluid in the lungs, which may cause death. Because hydrochloric acid is corrosive, it can cause eye damage, even blindness, if splashed in the eyes. Skin contact can cause severe burns and scarring. Ingestion of concentrated hydrochloric acid can cause severe injury to the mouth, throat, esophagus, and stomach. A single small exposure from which a person recovers quickly is not likely to cause delayed or long-term effects. Patients who breathe a large amount of hydrogen chloride may develop permanent lung injury. If hydrochloric acid is swallowed, a patient may permanently have trouble swallowing (36).
There is no data that suggest hydrogen chloride causes cancer or diabetes. Because ingestion of concentrated hydrochloric acid can cause severe corrosive injury to the lips, mouth, throat, esophagus, and stomach, victims may not be able to swallow or eat for some time, so weight loss is more likely to occur than obesity.
Children are more vulnerable than adults to toxicants affecting the skin. Children exposed to the same levels of hydrogen chloride gas as adults may receive a larger dose because they have greater lung volume to body weight ratios than adults. In addition, they may be exposed to higher levels than adults in the same location because of their short stature and because hydrogen chloride is heavier than air and higher levels of hydrogen chloride are found nearer to the ground (36).
Benzene was a raw material used at the site in manufacturing chlorinated benzene products. Standard Chlorine installed a waste recycling unit that began operation in 1997 to recycle some manufacturing wastes. The air permit issued by DNREC allowed the recycling unit to release 11 pounds of benzene per day. The air permit also said that the unit should be tested within 180 days after being constructed. Metachem purchased the property in 1998. When Metachem tested the recycling unit in late 1999, benzene emissions from the recycling unit were about 266 pounds per day–far in excess of the permit limit. It is not known if the benzene emissions were as high as that for the entire 3-year operating life of the recycling unit (8, 9). Metachem purchased benzene from the nearby Motiva Refinery, which undoubtedly also had benzene releases throughout the years. Benzene is widely used in the United States; it ranks in the top 20 chemicals for production volume. Other sources of benzene include volcanoes, forest fires, crude oil, gasoline, and tobacco smoke.
Benzene is a clear, colorless-to-light yellow liquid with a sweet aromatic odor. It is volatile and highly flammable. Benzene vapor is heavier than air and may cause asphyxiation in enclosed, poorly ventilated, or low-lying areas. It reacts with other chemicals in the air and breaks down within a few days. Benzene does not build up in plants or animals (38, 39).
Most exposures to benzene occur by inhalation. Its odor threshold generally provides adequate warning of acutely hazardous concentrations (see Table 12). Unleaded gasoline and tobacco smoke are major sources of the public's exposure to benzene. Outdoor air contains low levels of benzene from automobile service stations, exhaust from motor vehicles, and industrial emissions. Indoor air generally contains higher levels of benzene from tobacco smoke and from products such as glues, paints, furniture wax, and detergents that contain the chemical (38, 39).
Breathing very high levels of benzene (20,000 ppm for 5 minutes) can result in death, while high levels (3,000 ppm for 5 minutes) cause drowsiness, dizziness, rapid heart rate, headaches, tremors, confusion, blurred vision, unconsciousness, coma, and death. However, most victims regain consciousness rapidly after they are removed from exposure. Eating or drinking foods containing high levels of benzene can cause vomiting; irritation of the mucous membranes, esophagus, and stomach; dizziness; sleepiness; convulsions; abdominal pain; rapid heart rate; and death. The estimated lethal oral dose is 100 milliliters (3.4 ounces or a little less than ½ cup), although as little as 15 milliliters (1 tablespoon) has caused death (38, 39).
Long-term exposure to high levels of benzene in the air causes effects on the bone marrow and can cause anemia and leukemia. It can also cause excessive bleeding and can affect the immune system, increasing the chance for infection. Epidemiologic studies have shown that benzene is a human carcinogen (38, 39).
Children are more vulnerable than adults to benzene absorbed through the skin. They may also receive a higher dose than adults in the same location because they are shorter than adults and benzene vapors accumulate in low areas. Chronic exposure may be more serious for children because of their potential longer latency period. Parents should minimize children's exposure to benzene by not smoking around children, keeping household products containing benzene out of the reach of children, and minimizing children's exposure to gasoline fumes and exhaust from gasoline engines.
| Parameter | Chlorobenzene (31, 32, 37) |
Dichlorobenzene (33, 34, 37) |
Trichlorobenzene (35, 37) |
Hydrogen Chloride (36, 37) |
Benzene (37, 38, 39) |
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| Odor threshold (ppm) | 0.22-1.76 | 0.18 | 0.3 | 0.77 | 1.5-5 | ||||||||||||||||||||||||
| Rural air background (ppb) | <0.02 | 0.00 | No data | No data | No data | ||||||||||||||||||||||||
| Urban air background (ppb) | 0.8 | 0.02-20 | 0.03 | No data | No data | ||||||||||||||||||||||||
| MLK station average (ppb) | 0.01 | 0.04 | 0.00 | No data | 0.55 | ||||||||||||||||||||||||
| Inhalation | PEL: 75 ppm TWA: 10 ppm |
PEL: 75 ppm TWA: 10 ppm MRLs: 0.8 ppm acute, 0.2 ppm intermediate, 0.1 ppm chronic RfC: 0.8 mg/m3 |
TLV: 5 ppm ceiling - irritation | PEL: 5 ppm ceiling - irritation 2002 - STEL changed to 2 ppm IDLH: 50 ppm |
STEL: 2.5 ppm PEL: 1 ppm TWA: 0.5 ppm IDLH: 500 ppm |
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| Drinking Water Limit (mg/L) | 0.1 | 0.075 | 0.07 | None | 0.005 | ||||||||||||||||||||||||
| Oral (mg/kg/day) | RfD: 0.02 chronic | MRL: 0.4 intermediate | RfD: 0.01 | None | |||||||||||||||||||||||||
| Carcinogen | EPA Group D Not carcinogen. A3=Animal carcinogen with unknown relevance to humans |
Possible - EPA Group C A3=Animal carcinogen with unknown relevance to humans |
Indeterminant. Carcinogen (liver tumors) for mice, but not for rats. | A4=not classifiable as a human carcinogen | A1=confirmed human carcinogen (leukemia) | ||||||||||||||||||||||||
| Diabetes | No data | No data | No data | No data | No data | ||||||||||||||||||||||||
| Obesity | Weight loss | Weight loss | Retarded weight gain | Weight loss–if ingested causes vomiting and diarrhea | Weight loss–if ingested causes vomiting and diarrhea | ||||||||||||||||||||||||
| Health Effects | Headache, nausea, sleepiness, numbness, vomiting, irritation of eyes & respiratory track | High exposure: headache, dizziness, liver problems, eye
& nose irritation. Chronic Ingestion: skin blotches & low red blood cells. |
Irritating to eyes & respiratory track, lethargy.
Long term dermal doses: dermatitis. High doses (animals oral or dermal): hepatic toxicity or tremors, convulsions & death. |
Irritating to eyes, respiratory track & skin. Chemical burns. Ingestion causes severe injury to mouth, throat, esophagus, & stomach. | Irritating to eyes, skin & respiratory track. High levels by inhalation or oral: nausea, vomiting, dizziness, drowsiness, rapid heart rate, tremors, headaches, anemia, confusion, unconsciousness & death. | ||||||||||||||||||||||||
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People in the community have expressed concern about inhaling chemicals released from Metachem, eating produce grown near the plant, and getting cancer or diabetes or becoming obese from exposure to Metachem emissions. They also asked if exposure could cause autism.
According to the air data ATSDR has reviewed, there
is no health hazard to the general public from
inhalation of chemicals released to the air by the
Metachem or Standard Chlorine facility, either
currently or in the past 10-12 years. ATSDR does not
know what concentration of chlorinated benzenes the workers at the site and at industries nearby
may have been exposed to during the two large spills that occurred in the 1980s and during the
remediation activities to clean up the chemicals. ATSDR also does not know what concentrations
of benzene that workers were exposed to on-site from 1996 to 1999 from the benzene recycling
unit. Acute or chronic inhalation exposures to benzene and chlorinated benzenes may or may not
have occurred to on-site employees or workers at nearby industries during those time periods.
The facility is being closed, so that no future inhalation hazard exists from the manufacturing process. However, depending on the type of remediation technology used, there may be fugitive air emissions during removal of chemicals currently on the site and during excavation and processing of the contaminated soil and sediment or during treatment of the groundwater or wastes left on the site. The Delaware Department of Natural Resources and Environmental Control, EPA, and their contractors are monitoring the air on the site in various sections of the plant and requiring personnel to wear personal protection equipment as needed to prevent inhalation and dermal exposure to contaminants. The levels they have measured on the site near the fence line indicate that volatile organic compounds off the site are not at levels of health concern at this time.
Local residents expressed concern about possible exposures occurring when EPA contractors started processing products left in tanks through some of the distillation columns. So far, there have been no air releases that would cause adverse health effects since operations began July 17, 2003.
There are unfenced areas of the Metachem property (between the plant fence and Red Lion Creek
and the tributary to the Red Lion Creek) where the
soil and sediment have high levels of chlorinated
benzenes (see Table 8). This area is a health hazard to
anyone who may wander in this area. On the basis of
ATSDR staff members' observations during their site
visits, it is very unlikely that employees of other
industries in the area would trespass or wander onto
Metachem's unfenced property because of the dense thickets of briars and other vines and the
existence of marshes in that area of the site.
From the limited off-site soil data currently
available for areas east of the plant, it appears
that the OxyChem ball field area is not
contaminated; therefore, use of the ball field is not a public health hazard. In the preliminary
public health assessment released for public comment, ATSDR expressed concern that children
or families who came to the OxyChem ball field might wander into the unfenced contaminated
areas of the Metachem site (15). ATSDR also recommended that barriers be constructed to
prevent site entry. This final health assessment has been changed to delete those concerns and
recommendations. ATSDR staff have visited these areas and are now convinced that the marshes
surrounding the site on three sides and the dense thickets of briars and vines are sufficient natural
barriers to prevent trespassing. Also, workers in the area said that the ballfield was seldom used
during the last year.
ATSDR classifies the ingestion pathway as
currently no apparent health hazard because (1)
a fish advisory has been in effect for fish caught
in the Red Lion Creek since 1986; (2) surface
water intakes on Red Lion Creek and shallow
wells in the vicinity of Metachem that were previously used for drinking water have been closed;
(3) all drinking water wells within 1.5 miles of the site have been recently sampled and found to
be uncontaminated; and (4) it is unlikely that the fields near the site and the crops grown in the
fields are contaminated with chemicals from the Metachem site.
In general, children are more susceptible to health effects from exposure to chemicals than
healthy adults. Hydrogen chloride vapors and most of the vapors of the chlorinated benzene
chemicals used or manufactured at the Metachem
plant are heavier than air; therefore, in the event
of another release, the concentrations will be
higher closer to the ground. If another spill or
release occurs at the Metachem site while the
OxyChem ball field is being used, the ball field
should be evacuated immediately. Particular
attention should be placed on evacuating any children who are present as quickly as possible. The
entire plant area and the soil and sediment outside of the Metachem fence to the north and west
of the plant are a health hazard because of contamination with site-related contaminants, so that
children should not be allowed to enter the site.
Concerns about Specific Diseases
The following sections will discuss the community's specific concerns about a link between the site and cancer, diabetes, autism, and obesity.
There is no scientific data to support the allegation that the chemicals used or manufactured by Metachem could cause obesity. In fact, if sufficient exposure to any of the chemicals from Metachem (see Table 12) occurs, it could cause weight loss due to nausea, diarrhea, and vomiting.
ATSDR found no scientific data to support the allegation that the chemicals used or manufactured by Standard Chlorine or Metachem cause autism.
ATSDR did not find any data that indicate that exposure to the chemicals manufactured by or released from Metachem (see Table 12) could cause diabetes.
The data from the toxicological studies done to date on chlorobenzene, 1,4-dichlorobenzene,
1,2,4-trichlorobenzene, and hydrogen chloride indicate cancer due to exposure to these chemicals
is not likely to occur in the communities in New Castle County. However, benzene is a chemical
known to cause leukemia in humans. Because the community is concerned about cancer, ATSDR
looked at the cancer incidence rates for all types of cancer in Delaware compared to the rates for
the general U.S. population. According to the data published by the Delaware Department of
Health and Social Services' Epidemiology Branch, from 1980 to 1998 the age-adjusted incidence
rates for Delaware were a little higher then for the U.S. population. Both the Delaware and U.S.
population cancer incidence rates steadily increased from 1980 to 1995 and slowly declined
between 1995 and 1998 (40). See Figure 6. Delaware is in a very industrialized area of the
country, so that it is not possible to identify a single cause or industry that might be responsible
for the higher cancer incidence rate in Delaware. For more information on cancer rates in
Delaware, see the Delaware Division of Public Health Web site at http://www.delaware-epi.org/ .
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