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The Agency for Toxic Substances and Disease Registry (ATSDR) conducted an evaluation of theMetachem Products site in New Castle, Delaware, in response to public health concernsexpressed by a representative of a citizens group in the area. A spokesperson for the group "StopMetachem Products LLC" expressed concerns about whether people in the area were beingexposed to chemicals from the Metachem Products plant. A previous evaluation of the site, whenthe 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 beenraised by people in the community and (2) additional data are now available. This healthassessment 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.


Site Description and History

The Metachem site is 3 miles northwest of Delaware City, Delaware. The site is approximately46 acres in size and is located near the south bank of Red Lion Creek. In 1965, Standard Chlorineof Delaware, Incorporated, built a chemical plant on what was then farmland. The site is in thenorthwest portion of a large industrial area that is bordered on the north by Red Lion Creek, onthe east by the Delaware River, and on the south and west by farmland. Among the companies inthe area are the Motiva Refinery (also known as Getty Refining and Star Enterprises); ICIAmericas; Stauffer Chemical Company; American Mirrex; Zeneca, Incorporated; OccidentalChemical (formerly Diamond Shamrock Company, also known as OxyChem); and Air Productsand Chemicals, Incorporated. Most, if not all, of the companies in the area have wells fordrinking water, industrial process water, and/or groundwater monitoring (2-4).

According to the 2000 census, 144 individuals live within one mile of the Metachem site.On the north side of the site on the other sideof Red Lion Creek, there are farms and 46residences within a 1-mile radius of theMetachem site (see Figure 1). A few moreresidences 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 benzenecompounds, including chlorobenzene, 1,4-dichlorobenzene, 1,2-dichlorobenzene, and lesseramounts of 1,3-dichlorobenzene and trichlorobenzene. Although operations have varied over theyears, these chemicals were still the primary products produced at the facility by Metachem untilrecently (2, 6).

A release of approximately 5,000 gallons of chlorobenzene occurred in 1981.In September 1981, a release of approximately 5,000 gallons of chlorobenzene occurred at theStandard Chlorine Site while workers were filling a railroad tank car. Some of the chemical ranoff in surface ditches at the northwest andsouthwest corners of the plant (see Figure 2) andentered a tributary of the Red Lion Creek. Inresponse to the spill, the company took measuresto prevent the discharge from reaching the RedLion Creek. Under the direction of the DelawareDepartment of Natural Resources and Environmental Control (DNREC), Standard Chlorineconducted a groundwater investigation and found that the groundwater beneath the site wascontaminated with other chlorinated benzene compounds, in addition to chlorobenzene. Theprimary source for the other chlorinated benzenes found was believed to be a process drainagecatch basin that leaked before it was repaired in 1976 (2).

Standard Chlorine installed a groundwater recovery and treatment system in 1982. This systemwas upgraded over time, and in 1986 the current groundwater recovery and treatment system wasinstalled. The recovery wells are supposed to pump water from the shallow aquifer to controlplume migration and prevent contamination of the deeper Potomac Aquifer, which is a source fordrinking water in the area. However, the system has not been operated continuously. StandardChlorine and Metachem monitored the groundwater recovery and treatment system, and themonitoring has been documented in quarterly reports to the U.S. Environmental ProtectionAgency (EPA), Region III, and DNREC since 1988 (2, 7). These reports document that the wellswere seldom pumped in 2001 and during the first part of 2002. The system is still not operatingcontinuously. EPA is evaluating the effectiveness of the system and what upgrades are needed.

In 1986 approximately 400,000 gallons of 1,4-dichlorobenzene and about 169,000 gallons of trichlorobenzene were released.The second major release at the StandardChlorine facility occurred on January 5, 1986.Approximately 400,000 gallons of 1,4-dichlorobenzene and about 169,000 gallons oftrichlorobenzene were released when a 375,000gallon tank split open. The tank collapsed and damaged three nearby tanks, causing those tanksto spill some of their contents. The spilled chemicals flowed across the plant property and off thesite to an unnamed tributary to Red Lion Creek (see Figure 2). The tributary is to the west of thefacility. Some of the contaminants migrated from the mouth of the tributary along the southernshoreline of Red Lion Creek. In response to the 1986 spill, DNREC and Standard Chlorine tookthe following emergency actions: (1) booms, dikes, and a filter fence along the mouth of thewetland coves were used to contain and minimize further discharge; (2) some of the material thathad flowed off the site was recovered; (3) pre-excavation sampling was conducted and an earthendike 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-linedcontainment pond was constructed to store dredged materials (2, 7).

Standard Chlorine of Delaware sold the plant to Metachem Products in 1998.The Standard Chlorine site was proposed to theU.S. Environmental Protection Agency'sNationalPriorities List for Uncontrolled HazardousSubstances (NPL) on September 18, 1985. The sitewas formally added to the NPL on July 1, 1987, making the site a "Superfund site" for which theEPA had authority to oversee clean-up activities. Metachem Products bought the facility fromStandard Chlorine of Delaware in 1998. As part of the purchase agreement, Metachem assumedliability for the Superfund clean-up requirements that might be required at the site by EPA (2).

From 1996 to 1999 the recycling unit may have released up to 266 pounds of benzene a day.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).

In May 2002, Metachem closed the plant.Until recently, Metachem operated thechlorobenzene manufacturing facility, which hadair and water discharge permits. In May 2002,Metachem notified EPA and the state that it was closing the manufacturing operations and filingfor bankruptcy. Metachem removed materials from some of the processing equipment, but leftmost of the chemicals and wastes on the site (6).

EPA Site Activities

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 sitehas two components: an interim action for groundwater and a final action for contaminated soiland sediment. The interim action for groundwater specified containment of groundwater tominimize the continued release of contaminants. It included the following requirements:

  • Construct a subsurface physical barrier such as a trench or slurry wall to containgroundwater and dense nonaqueous phase liquids (DNAPLs).

  • Install low-volume recovery wells to remove pools of DNAPLs identified duringremedial design.

  • Repair and upgrade (if necessary) the existing groundwater pump-and-treat system.

  • Treat contaminated groundwater in the existing waste water treatment plant and treat all air emissions that might occur during the treatment process.

  • Establish institutional controls to include deed restrictions and a GroundwaterManagement Zone.

  • Determine the extent of groundwater contamination.

  • Evaluate the technical practicability of remediating groundwater to health-basedconcentrations of chlorinated organics (2).

The record of decision designated the preferred final action for soil and sediment to be biologicaltreatment. Standard Chlorine was supposed to bioremediate the soil and sediment along thewestern drainage gully, the eastern drainage ditch, the area adjacent to Catch Basin 1, along therailroad tracks, and along the unnamed tributary to Red Lion Creek. In addition, StandardChlorine was to bioremediate the soil in the waste piles and in the sedimentation basin using insitu (in place) or ex situ (excavated) treatment. If it was determined that bioremediation wouldnot be feasible for the site (based on the results of treatability studies or further testing) the recordof decision designated a preferred contingency remedy: low temperature thermal desorption (2).

Numerous complaints have been received about odors and air emissions from the site.Over the years, EPA Region III and DNREChave received numerous complaints about odorsand air emissions from the Metachem facilityfrom an individual who lives in Newark,Delaware, which is approximately 10 miles west of the site. The resident formed a citizensgroup, 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 variouscomplaints and issues raised by the Coalition and discusses the investigations and actions takenby EPA to address the complaints (10). In July 2000, the EPA Office of Inspector General'sengineering and science staff evaluated Metachem's chlorobenzene manufacturing process todetermine "...the potential for the chlorobenzene process to 'poison' the surrounding community(especially in regards to chlorinated dioxins)..."(11).

In 2001 ATSDR was petitioned to conduct a public health assessment of Metachem.One allegation the engineering and science staff investigated was whether the chlorobenzeneemissions from the manufacturing process could be converted by sunlight into dioxins andfurans. The staff found that the chemical literature indicates that sunlight degradeschlorobenzenes into hydrocarbons and hydrochloric acid. Regarding the production of dioxinsduring the manufacturing process, the staff found that the feedstock for the hydrogenationprocess 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 favorablefor the generation of additional dioxins. However, the conditions in the reactor will also notdestroy dioxin that may be entrained in the feed stock. More importantly, the hydrogenationreactor is designed to dechlorinatepolychlorinated-benzene rings and will alsoprobably dechlorinate the more chlorinateddioxin/furan congeners into the lowerchlorinated dioxin/furan congeners (for example, pentachloro- to tetrachloro- and hexachloro- topentachloro-, and so on), a process that could increase the toxicity of the dioxin mixture. Thestaff concluded, "Air emissions of dioxin/furans are an insignificant pathway since the chemicalproperties of dioxin/furans do not favor their partition into the vapor phase. Therefore, the onlysignificant source for the release of dioxin/furans from the Metachem facility are the smallamount of dioxin/furans that are potentially entrained in the chlorobenzene products. Since thesechlorobenzene 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 underthe 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 productsfrom the facility, cleaning and decontaminating the facility (tanks, pipes, equipment, andconcrete structures), operating the waste water treatment facility, and providing site security(6,12).

ATSDR Site-Related Activities

ATSDR first became involved with the site when the Standard Chlorine Site was listed as anNPL site in 1987. The agency prepared a draft preliminary public health assessment and releasedit for public comment August 16, 1988 (13). The Preliminary Health Assessment for StandardChlorine Company, Delaware City, New Castle County, Delaware was issued as a finaldocument March 16, 1989 (1). ATSDR concluded that the site posed a potential public healththreat 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 andfishing may be at increased risk of possible adverse health risks through direct contact with thewater and through ingestion of fish that bioaccumulate site-related contaminants. ATSDRrecommended that future site investigations include (1) characterization of the site and impactedoff-site areas to evaluate the potential human exposure pathways and (2) a characterization of thehydrogeology of the area (1).

In June 2001, ATSDR received several letters from the spokesperson for the Stop MetachemProducts LLC (previously the Coalition to Stop Metachem's Polluting) asking the agency to lookinto 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 petitionfor a public health assessment. The agency agreed to review the health concerns described in thepetitioner's letters, review any new information about the Standard Chlorine/Metachem site, anddetermine whether an update of the public health assessment was indicated (14). ATSDR staffhave reviewed information available since the preliminary health assessment was published andprepared this updated public health assessment to address site conditions and communityconcerns.

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-November2002. The first comment period ended January 31, 2003. Comments were received from twocommunity members.

ATSDR staff tried to visit the site and meet with concerned residents a couple of times during thewinter, but they had to cancel the travel because of bad snow storms. On March 12, 2003, stafftoured 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 theDelaware City Fire Hall. A second day of meetings was scheduled for May 1, 2003, at theGunning Bedford Middle School cafeteria. Two public availability sessions were held from3:00-4:30 pm and 7:00-9:00 pm. A press briefing was planned for 4:30-5:00 pm, but no pressshowed up. The public comment period was extended until May 16, 2003. All comments relatedto the potential health effects caused by the Metachem facility that were received in writing ordiscussed 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, ATSDRstaff observed an elderly gentleman fishing from the Red Lion Creek bank where highway 9crosses the creek. The staff stopped and advised the man that he should not eat any fish caught inthe creek or in the Delaware River. So far, he had not caught any fish. ATSDR staff noticed thatthe 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 haveoccurred during the operating life of the Standard Chlorine and Metachem facility, that maycurrently be occurring, or that might occur in the future. This assessment evaluates the potentialpathways by which the public might be exposed to chemicals from the site, including theexposures about which the community has expressed concerns. A separate section will discusseach of the ways (pathways) that persons could be exposed to chemicals from Metachem: byinhaling 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 eatingor drinking food or ground water that is contaminated (ingestion pathway). Each pathway sectionwill discuss the potential for exposure in the past, as well as whether exposure is currentlyoccurring.

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 healtheffects 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

Community Concerns

The community is concerned that the manufacturing process generated dioxins that were releasedinto the air along with the chlorinated benzene products manufactured at the facility. Thepetitioner specifically mentioned concerns about air releases of the following chemicals: 2,3,7,8-dioxins, dioxins, benzene, 1,3-dichlorobenzene, paradichlorobenzene, and chlorobenzene. Someresidents believe releases from the facility have caused public exposure at levels that causedhealth effects. Health effects mentioned were cancer (ovarian, liver, kidney, breast, cervical,leukemia, and bone), diabetes, autism, high blood pressure, and obesity. Community membersalso 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 significantquantity of data related to the Metachem site and New Castle County, where the facility islocated and the petitioner resides.

ATSDR obtained from the EPA Web page an AIRData report containing data extracted from theJune 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 released68,271 total pounds of HAPs into the air in 1996. While this sounds like a lot of air pollution, itwas 1.17% of all point source air emissions in Delaware. Industries in Delaware released a totalof 5,851,291 pounds of HAPs that year. Table 2 shows the hazardous air pollutants released byStandard Chlorine in 1996 (16).

Table 2.

Site Pollutant Emissions in 1996 (16)
PollutantEmissions (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 seasondaily emissions provided by the DNREC Division of Air and Waste Management for 1996, asshown in Table 3 (17). Note that the site emissions in Table 2 are in pounds per year and thequantities in Table 3 are given in tons per day.

Volatile organic compounds (VOCs) are the primary contributors to the formation of ozone. Thepeak ozone season is the summer, so that Delaware conducts air sampling for VOCs, nitrogenoxide 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, chemicalmanufacturing plants, refineries, auto assembly plants, solid waste landfills, and large buildingheating systems that have stacks or vents. Metachem is in the point source category. Tables 2 and3 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)

Table 3.

1996 Statewide Peak Ozone Season Daily Emissions (17)
Source Category Pollutant Emissions in Tons Per Day (TPD)
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

Stationary or Area Sources include sources such as dry cleaners, auto shops, gas stations, printshops, painting operations, degreasing and other solvent-using operations, small building heatingsystems, and other small businesses that may each emit small quantities of VOCs or CO. Addedtogether, the VOC emissions from these sources are greater than those from larger industrialplants, and those emissions contribute significantly to the formation of ozone.

The Mobile Source category includes automobiles, trucks, motorcycles, ships, recreationalboats, trains, airplanes (commercial, military, and private), tractors and other farm equipment,engines on construction equipment, and such items as lawn mowers, chain saws, and leafblowers. Most engines in this category have no emission controls and are considered highemitters of VOCs.

Biogenic Sources include emissions from plant life in the area, such as crops, trees, grasses, andother vegetation. While biogenic sources emit significant quantities of VOCs into the atmospherethat may contribute to ozone formation, they also remove significant amounts of CO, sulphurdioxide, NOx, ozone, and particulate matter from the air and also cool the air, thus reducingpollution from other sources (17).

In 2001 ATSDR was petitioned to conduct a public health assessment of Metachem.According to the EPA 1999 Toxics ReleaseInventory report for Delaware, Metachemreleased 106,159 pounds of reportablechemicals, which was 1.28% of the total on-site releases (to air, water, and land) in thestate in 1999 (see Table 4).

Table 4.

1999 Toxics Release Inventory for Delaware (18)
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 thatalso contribute to the air pollution in Delaware, it is not surprising that local residents can smellchemicals when they are outdoors. Hydrogen chloride is the only chemical in the top tenchemicals 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 samplesand 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 onWrangle Hill Road southeast of the industrial area (19), and an air monitoring station at LumsPond State Park (20). The ball field is about one mile southeast of Metachem, halfway betweenthe industrial park and Delaware City. Table 5 presents a summary of results of air data from thestations at Wilmington and the Delaware City ball field for 2000 and 2001. Table 6 presents asummary of the 2002 air data from all three air monitoring stations. When the air concentrationsin 2000-2002 (shown in Tables 5 and 6) are compared to health values for the chemicals thatmay be related to emissions from Metachem (in Table 12), one can tell that the off-siteconcentrations of these chemicals that the public is exposed to are below levels that would causehealth 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 concentrations of organic chemicals from Metachem that were measured in the air are not likely to cause public health effects in residents. The same may not be true for on-site workers in the past.The DNREC air monitoring stations do not collect samples for dioxin compounds, a class ofchemicals the community is particularly concerned about. In September 2002, EPA collectedeight 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 0.025to 0.133 pg/m3. An indoor air sample recently taken in the Metachem warehouse contained 0.49pg/m3 dioxin TEQ (20). In November 2002, the four air samples EPA took at the site perimeterranged in dioxin concentrations from0.02 to 0.04 pg/m3 TEQ. All of theseon-site concentrations are belowconcentrations that are expected tocause adverse health effects. If oneassumes that the Metachem facility isthe source of the dioxins that weremeasured in the outdoor air samples, then concentrations at the closest residence would be manytimes lower and probably not detectable. Public health effects are not expected from exposure tosuch low concentrations of dioxin compounds.

All of the air data reviewed by ATSDR staff indicate that the off-site concentrations of theorganic chemicals that could have been released from the Metachem site are not currently (or inthe last four years) at levels likely to cause adverse health effects in the general population ofNew Castle County. While the general public is not expected to be exposed to chemicals fromMetachem by the air pathway, this may not be true in the past for on-site workers or foremployees of companies nearby. During the two major spills and their cleanup and during theoperation of the waste recycling unit from 1996 to 1999, workers in the area around the site mayhave been exposed by the air pathway to levels of benzene and chlorinated benzene productsabove health-based screening values. Because the concentration of chemicals that workers werepotentially exposed to is not known, this health assessment discusses the toxicology of thechemicals 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 airsampling methods to determine their usefulness in monitoring air concentrations of chemicals atSuperfund sites. The various sampling methods were used to take air samples at five Superfundsites 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 StarEnterprises' (now called Motiva) oil storage facility. Samples were also taken by several othersampling methods in the communities near the site. The community sampling locations were theWilliam Bubby Sadler ball field about 1 mile southeast of the industrial complex and twolocations 2-3 miles north-northeast of the complex. The locations of the northern samples wereat 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 StandardChlorine.

Table 7 contains the data for the fence line samples taken at Metachem and Motiva and theaverage of the samples taken in the community. The fence line samples were collected "onlywhen there were indications that an 'event' was occurring, such as smells, data from real-timeinstrumentation or obvious plumes."(22) The fence line data, therefore, provide someinformation on concentrations of chemicals to which on-site workers were typically exposed inthe late 1980s. The report and articles published about the Delaware study do not give theconcentrations measured at the Llangollen Estates location; they say only that "the concentrationsat the sites 1-3 miles away from specific sources are essentially at background levels, generallynot exceeding 2 ppb."(22) The average air concentrations for chemicals related to the Metachemsite 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)

Soil and Sediment

It is unlikely that the public will come in contact with contaminated soil, sediment, or water.Metachem employees and remediation workers may come in contact with on-site and off-site soiland sediment that are contaminated from process leaks and the two major spills that occurred atthe site. Because there are no residences near the northwest portion of the industrial area andthere are marshes along the banks of theRed Lion Creek and its tributaries, it ishighly unlikely that the public willcome into contact with thecontaminated 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 marshesalong the banks of Red Lion Creek, swimming and other activities that would result in longerdermal exposure to the surface water and sediments are not considered likely.

On-site soils are very contaminated. Remediation workers should wear appropriate personal protective equipment to prevent exposure.Employees of the companies adjacent to Metachem (Air Products to the west and OxyChem tothe east) may come into contact with off-site soil and sediment contaminated bychemicals from Metachem if theywander through the unfenced area northof the Metachem plant or along theunnamed tributary west of Air Productsand Metachem. According to ATSDRstaff members' observations during site visits, it is very unlikely that employees of otherindustries in the area would trespass or wander onto Metachem's unfenced property because ofthe dense thickets of briars and other vines and the marshes in that area of the site.

Barriers and signs should be placed at any paths, clearings, or roads that lead into the contaminated areas that are currently unfenced.The two major spills ran primarily in drainage ditches to the west into the unnamed tributary ofRed Lion Creek. During the 1986 spill, however, materials also flowed across the site to theeastern drainage ditch and northward to the unnamed tributary (see Figure 2). Employees saidthat in a loading dock area on site the chemicals were about four feet deep. According to the EPARecord of Decision, the concentrations of total chlorinated benzene compounds in on-site surfacesoils (inside the existing plant fence) rangefrom 1.2 milligrams per kilogram (mg/kg)to 68,427 mg/kg (see Table 8). Typically,the concentrations of chlorinated benzenewere much lower in the subsurface. Theconcentrations of total chlorinated benzenecompounds in surface soils outside the existing plant fence and the concentrations of totalchlorinated benzene compounds in off-site sediments are shown in Table 8. More recent soil andsediment samples taken during 2002 and 2003 generally contained lower concentrations ofchlorinated benzene compounds; however, the data clearly show that the site is contaminated andcontinues to need remediation (24). Remediation workers should wear appropriate personalprotective equipment to prevent dermal exposure to highly contaminated equipment, soil, andsediment both on and off the site.

From the data and figures ATSDR has reviewed, it appears that the OxyChem ball field to theeast of the site was not contaminated by the spills from Metachem (2). Figure 5 shows an aerialview 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

Surface Water

Chemical concentrations in Red Lion Creek are too low for dermal contact with the water to be a public health concern.During the remedial investigation, low levels of chlorinated benzene compounds were detected insurface water samples collected from Red Lion Creek and the unnamed tributary to Red LionCreek. The concentrations ranged from 10 to 360 micrograms per liter (2). The higherconcentrations were generally in samples collected from surface water in the unnamed tributarywhere public exposure is very unlikely.Recent surface water sampling data are notavailable. Because the groundwater thatdischarges to the tributary and creek is stillcontaminated and the sediments have notbeen remediated, the surface water is likelyto still contain low levels of chlorinated benzene compounds. Boating or other recreational use, ifany, of Red Lion Creek down stream from the site may result in brief, intermittent exposure tosurface water, but the chemical concentrations in Red Lion Creek are too low for dermal contactwith the water to be a health concern.

Products and Process Wastes

Metachem submitted a report to the State of Delaware, Dioxin and Furan Testing Data, datedMarch 29, 2001 (25), that contains all the dioxin and furan data that were in the Metachem filesat that time. In 1996, a number of process samples were analyzed. Some process samplescontained dioxins and furans, while samples from other parts of the process contained nodetectable 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 inpicograms per gram (pg/g) concentrations. In 2002 and 2003, EPA contractors sampled andanalyzed soils, sediments, products, and waste products for dioxins and furans. Table 9 containsthe EPA dioxin data. Because the manufacturing wastes are disposed of at a hazardous wastefacility, 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
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 byeating crops grown in the fields around the industrial area, by eating fish from Red Lion Creekand the Delaware River, and by drinking contaminated groundwater. This section examines thedata available on the site-related chemicals present in each of these media.


ATSDR considers the produce grown in the fields near the site to be no public health hazard.The petitioner and local residents areconcerned about whether it is safe to eatcrops grown in the fields around theindustrial area where Metachem islocated. They question whether dioxin or chlorinated benzenes from Metachem haveaccumulated in soil and in produce grown near the plant. ATSDR does not have data from theanalysis of crops grown in the area or soil samples taken from the fields where food crops aregrown. However, EPA Region III provided soil data taken in off-site areas around the plant toidentify the areas affected by the company and needing to be remediated. When one gets awayfrom the areas where spilled products exist, the soil concentration of total chlorinated benzenesquickly falls below the detection limit of 0.5 mg/kg (2).

One would expect to find higher concentrations of settled airborne contaminants in undisturbedsurface soil near the facility than in cultivated soil a half mile or more from the facility. Nearbysoils could be affected by deposition from fugitive emissions as well as stack emissions. ATSDRconsiders that produce grown in the fields near the site present no public health hazard for tworeasons. First, the surface soil near Metachem, except for the areas affected by the Metachemspills, does not present a health hazard. Second, farm practices, such as aeration, irrigation, andfertilization, are conducive to biodegradation of organic compounds (like chlorinated benzenes, ifany are present), making it unlikely that organics from Metachem have accumulated in the soil orin the crops in farmland near the facility. Although ATSDR thinks that it is unlikely thatMetachem 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 moredefinitive answer to this community concern.


Eat no more than three 8-ounce meals of fin fish caught in Red Lion Creek per year.Contaminants from the Metachem spills andother industrial discharges havebioaccumulated in edible marine life in RedLion Creek. In 2000-2001, an ecological riskassessment was conducted for the Metachemsite. The assessment included analyzingsamples of fish collected from Red Lion Creek (26). The following types of fish were caught andanalyzed: mummichog, pumpkinseed, brown bullhead, and American eel. Table 11 lists only thechemicals detected in the fish tissue samples.

A fish consumption advisory issued on May 2, 1986, by the Delaware Department of NaturalResources and Environmental Control (DNREC) and the Delaware Division of Public Healthrecommended 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 LionCreek 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 peoplecomply 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 Columbia aquifer is very contaminated beneath the site and north to Red Lion Creek.The uppermost aquifer beneath Metachem is the Columbia aquifer. In most areas the depth togroundwater in this aquifer ranges from 30 to 60 feet below ground surface. Some members ofthe community commented that it isshallower in some areas. The generaldirection of groundwater flow in theColumbia is to the north-northwest and northtoward the unnamed tributary and Red LionCreek. The Columbia aquifer beneath the site and northward to Red Lion Creek is verycontaminated with chemicals from process leaks and the two large spills at Metachem. There is alayer 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 DNRECshow that there are a number of drinkingwater wells within aAll the shallow drinking water wells in the vicinity of Metachem and its plume have been closed. mile of Metachemthat pump water from the Columbiaaquifer 30-40 feet below ground. However, industries near Metachem purchase drinking waterfrom 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 ofDNREC).

In December 2002 and January 2003, the Delaware Division of Public Health, Office of DrinkingWater sampled the water from wells within a 1.5-mile radius of the Metachem facility. Thesamples were all collected from inside taps of homeowners, either a kitchen sink or a bathroomsink, or at a hand sink if the sample was collected from a business. The samples were not filteredprior to analysis. EPA Method 524.2 was used to analyze the samples for 62 volatile organiccompounds (VOCs), which included chlorobenzene compounds (29, 30). Fourteen samplescontained no VOC contaminants. Two samples had low levels of VOCs that were below drinkingwater 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 waterstandard is 5 ppb and 80 ppb for DCA and trihalomethanes, respectively. The Delaware Divisionof Public Health concluded that "contaminants from the Metachem facility have not impacted thedrinking water wells in the vicinity. Therefore, drinking from these wells does not exposeindividuals to increased health risk from volatile organic chemicals."(29)

All drinking water wells within 1.5 miles have been sampled. There is no current public health hazard from the ingestion of groundwater.Because no one is currently drinkinggroundwater near the Metachem plume ofcontamination, there is no current publichealth hazard from the ingestion ofgroundwater. Unless deed restrictions andprohibition of the use of the Columbia aquifer for drinking water in the vicinity of Metachem areenforced, however, public exposure to contaminated groundwater could occur in the future.

Since 1982, Standard Chlorine and then Metachem have intermittently pumped and treated thecontaminated 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 hadpumped a cumulative total of 470,179,000 gallons of groundwater and recovered a total of141,834 kilograms of chlorinated benzene compounds (28). However, the groundwater is stillvery contaminated. EPA and DNREC are evaluating how to remediate the groundwater under thesite.

Toxicity of Site-Related Chemicals

This section will discuss the predominant chemicals released from the Standard Chlorine andMetachem facility: chlorobenzene, 1,4-dichlorobenzene, 1,2,4-trichlorobenzene, hydrogenchloride, and benzene. The residents of New Castle County should not be concerned that theymight have any of the health effects discussed in this section because it is unlikely that evenduring the spills that residents were exposed to any of these chemicals at levels that would causehealth effects. The toxicity section is included because of the potential that workers at thefacility, or near it, may have been exposed to significant concentrations of these chemicals duringspills 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 ToxicRelease Inventory data), and 5,000 gallons of it were released onto the ground in 1981 whenworkers were filling a railroad car. It is primarily used as a chemical intermediate in themanufacture of other products.

Chlorobenzene is a colorless, flammable liquid with an aromatic, almond-like odor. Whenreleased to the air, it is slowly broken down by reactions with other chemicals and sunlight or itcan be removed by rain. In water, chlorobenzene will rapidly evaporate or be broken down bybacteria. When released to soil, it is broken down rapidly by bacteria, but some of thechlorobenzene will evaporate to the air and some may filter into the groundwater. It does notbuild up in the food chain (31).

In studies of workers exposed to high levels of chlorobenzene in the air, the workers complainedof headaches, nausea, sleepiness, numbness, and vomiting. In studies of animals, central nervoussystem effects reported included unconsciousness, tremors, restlessness, and death. In studies ofanimals exposed for longer periods of time, liver and kidney damage was reported. The limiteddata 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 notproduce cancer in animal studies conducted with rats and mice, liver nodules that can lead tocancer were produced in male rats. EPA has determined that chlorobenzene is not classifiable asto human carcinogenicity because there is inadequate evidence in studies of both humans andanimals (31, 32).

There is very little information on how children react to chlorobenzene exposure, but childrenwould probably show the same effects as adults. There is a report that a 2-year-old male whoswallowed 5 to 10 cubic centimeters of chlorobenzene became unconscious, did not respond toskin stimuli, and had muscle spasms, but recovered uneventfully. There is no credible evidencethat chlorobenzene causes birth defects (32).


1,4-Dichlorobenzene (also known as paradichlorobenzene) is a household chemical commonlycalled mothballs that is used to control moths, mold, and mildew and to deodorize restrooms andwaste containers. At room temperature, it is a white solid that slowly changes to a vapor whenexposed to air. It is the vapor that acts as a deodorizer and insect killer. Most people can smell itat very low levels and can recognize the smell as that of mothballs. On January 5, 1986, about400,000 gallons of 1,4-dichlorobenzene was spilled at the site. In air, 1,4-dichlorobenzene breaksdown to harmless products in about a month (33, 34). Table 12 provides additional informationon this chemical. There is no evidence that moderate use of 1,4-dichlorobenzene will result inharmful health effects. Harmful effects, however, may occur from high exposures. Very highusage in the home can cause dizziness, headaches, and liver problems. There are cases of peoplewho ate 1,4-dichlorobenzene products regularly for months to years. These people had adversehealth effects, such as skin blotches and lower numbers of red blood cells (33, 34). People shouldnot eat 1,4-dichlorobenzene.

There is no direct evidence that 1,4-dichlorobenzene can cause cancer in humans. However, instudies of animals given very high levels of the chemical in water, the animals developed liverand kidney tumors. Therefore, ATSDR considers that 1,4-dichlorobenzene may reasonably beanticipated to be a carcinogen. EPA classifies it as a Group C carcinogen, that is, a possiblehuman 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 toiletdeodorizers containing 1,4-dichlorobenzene should make sure that children do not drink waterfrom the toilet bowl or play with the water. There is very little information on how children reactto 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 achemical 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 likelyto stay in soil and water if it is released to the environment. It is persistent in the environmentbecause it strongly adsorbs to soils. Trichlorobenzene is expected to bioaccumulate in aquaticorganisms. Once in the air, it breaks down photochemically with an estimated half-life ofapproximately 18.8 days (35). In January 1986, about 169,000 gallons of trichlorobenzene werespilled during the tank collapse and release at Standard Chlorine.

Trichlorobenzene is readily absorbed when oral, inhalation, and dermal exposure occur. Directcontact with the chemical irritates the skin and may cause dermatitis. Its vapors irritate the eyesand respiratory tract. In studies of animals given high oral or dermal doses, tremors andconvulsions, followed by death, occurred. Animal studies have also shown that trichlorobenzenecan 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. Largeamounts of it in the diet of animals caused cancer in mice but not in rats. From this conflictinganimal data it is not possible to determine the potential of trichlorobenzene to cause cancer inhumans (35). Household products containing 1,2,4-trichlorobenzene should be kept out of thereach of children.

Hydrogen Chloride

Hydrogen chloride is a colorless to slightly yellow, nonflammable gas with a sharp, irritatingodor. When hydrogen chloride dissolves in water, it forms hydrochloric acid, also known asmuriatic acid. Hydrochloric acid is a component of commercial chemicals used to clean anddisinfect 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 inmanufacturing polymers, plastics, rubber, fertilizers, dyes, and chlorinated solvents (36).

Atmospheric moisture causes hydrogen chloride to form a dense white vapor when it comes incontact 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 warningfor acute, high-level exposures. However, at the permissible exposure limit of 5 ppm set by theOccupational Safety and Health Administration, only 50% of exposed persons can perceivehydrogen 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 burnson contact. Hydrogen chloride is not absorbed through the skin. Hydrogen chloride gas canirritate the lungs, causing a cough and shortness of breath. Breathing high levels of the gas orvapor can lead to a buildup of fluid in the lungs, which may cause death. Because hydrochloricacid is corrosive, it can cause eye damage, even blindness, if splashed in the eyes. Skin contactcan cause severe burns and scarring. Ingestion of concentrated hydrochloric acid can cause severeinjury to the mouth, throat, esophagus, and stomach. A single small exposure from which aperson recovers quickly is not likely to cause delayed or long-term effects. Patients who breathe alarge amount of hydrogen chloride may develop permanent lung injury. If hydrochloric acid isswallowed, a patient may permanently have trouble swallowing (36).

There is no data that suggest hydrogen chloride causes cancer or diabetes. Because ingestion ofconcentrated 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 lossis more likely to occur than obesity.

Children are more vulnerable than adults to toxicants affecting the skin. Children exposed to thesame levels of hydrogen chloride gas as adults may receive a larger dose because they havegreater lung volume to body weight ratios than adults. In addition, they may be exposed to higherlevels than adults in the same location because of their short stature and because hydrogenchloride 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 andhighly 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 downwithin 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 adequatewarning of acutely hazardous concentrations (see Table 12). Unleaded gasoline and tobaccosmoke are major sources of the public's exposure to benzene. Outdoor air contains low levels ofbenzene from automobile service stations, exhaust from motor vehicles, and industrial emissions.Indoor air generally contains higher levels of benzene from tobacco smoke and from productssuch 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 highlevels (3,000 ppm for 5 minutes) cause drowsiness, dizziness, rapid heart rate, headaches,tremors, confusion, blurred vision, unconsciousness, coma, and death. However, most victimsregain consciousness rapidly after they are removed from exposure. Eating or drinking foodscontaining 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 andcan cause anemia and leukemia. It can also cause excessive bleeding and can affect the immunesystem, increasing the chance for infection. Epidemiologic studies have shown that benzene is ahuman carcinogen (38, 39).

Children are more vulnerable than adults to benzene absorbed through the skin. They may alsoreceive a higher dose than adults in the same location because they are shorter than adults andbenzene vapors accumulate in low areas. Chronic exposure may be more serious for childrenbecause of their potential longer latency period. Parents should minimize children's exposure tobenzene by not smoking around children, keeping household products containing benzene out ofthe reach of children, and minimizing children's exposure to gasoline fumes and exhaust fromgasoline engines.

Table 12.

Metachem Chemicals
Parameter Chlorobenzene
(31, 32, 37)
(33, 34, 37)
(35, 37)
Hydrogen Chloride
(36, 37)
(37, 38, 39)
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

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.
ppm parts per million ppb parts per billion PEL permissible exposure limit
TWA 8-hour, time weighted average MRL minimum risk level RfC reference concentration (air/inhalation)
TLV threshold limit value STEL short-term exposure limit mg/L milligrams per liter
IDLH immediately dangerous to life or health RfD reference dose (ingestion) mg/kg/day milligrams per kilogram per day


People in the community have expressed concern about inhaling chemicals released fromMetachem, eating produce grown near the plant, and getting cancer or diabetes or becomingobese from exposure to Metachem emissions. They also asked if exposure could cause autism.

There is no health hazard to the general public from inhalation of chemicals released from Metachem.According to the air data ATSDR has reviewed, thereis no health hazard to the general public frominhalation of chemicals released to the air by theMetachem or Standard Chlorine facility, eithercurrently or in the past 10-12 years. ATSDR does notknow what concentration of chlorinated benzenes the workers at the site and at industries nearbymay have been exposed to during the two large spills that occurred in the 1980s and during theremediation activities to clean up the chemicals. ATSDR also does not know what concentrationsof benzene that workers were exposed to on-site from 1996 to 1999 from the benzene recyclingunit. Acute or chronic inhalation exposures to benzene and chlorinated benzenes may or may nothave 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 manufacturingprocess. However, depending on the type of remediation technology used, there may be fugitiveair emissions during removal of chemicals currently on the site and during excavation andprocessing of the contaminated soil and sediment or during treatment of the groundwater orwastes left on the site. The Delaware Department of Natural Resources and EnvironmentalControl, EPA, and their contractors are monitoring the air on the site in various sections of theplant and requiring personnel to wear personal protection equipment as needed to preventinhalation and dermal exposure to contaminants. The levels they have measured on the site nearthe fence line indicate that volatile organic compounds off the site are not at levels of healthconcern at this time.

Local residents expressed concern about possible exposures occurring when EPA contractorsstarted processing products left in tanks through some of the distillation columns. So far, therehave been no air releases that would cause adverse health effects since operations began July 17, 2003.

Unfenced areas of the Metachem site are a health hazard to anyone who trespasses in that area.There are unfenced areas of the Metachem property (between the plant fence and Red Lion Creekand the tributary to the Red Lion Creek) where thesoil and sediment have high levels of chlorinatedbenzenes (see Table 8). This area is a health hazard toanyone who may wander in this area. On the basis ofATSDR staff members' observations during their sitevisits, it is very unlikely that employees of otherindustries in the area would trespass or wander ontoMetachem's unfenced property because of the dense thickets of briars and other vines and theexistence of marshes in that area of the site.

The ball field is not a public health hazard.From the limited off-site soil data currentlyavailable for areas east of the plant, it appearsthat the OxyChem ball field area is notcontaminated; therefore, use of the ball field is not a public health hazard. In the preliminarypublic health assessment released for public comment, ATSDR expressed concern that childrenor families who came to the OxyChem ball field might wander into the unfenced contaminatedareas of the Metachem site (15). ATSDR also recommended that barriers be constructed toprevent site entry. This final health assessment has been changed to delete those concerns andrecommendations. ATSDR staff have visited these areas and are now convinced that the marshessurrounding the site on three sides and the dense thickets of briars and vines are sufficient naturalbarriers to prevent trespassing. Also, workers in the area said that the ballfield was seldom usedduring the last year.

To avoid exposure by ingestion the public should comply with the fish advisories for Red Lion Creek and the Delaware River.ATSDR classifies the ingestion pathway ascurrently no apparent health hazard because (1)a fish advisory has been in effect for fish caughtin the Red Lion Creek since 1986; (2) surfacewater intakes on Red Lion Creek and shallowwells 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 tobe uncontaminated; and (4) it is unlikely that the fields near the site and the crops grown in thefields are contaminated with chemicals from the Metachem site.

Children's Susceptibility

If children attend events at the OxyChem ball field, the children should be closely supervised and not allowed to play in the surrounding industrial areas.In general, children are more susceptible to health effects from exposure to chemicals thanhealthy adults. Hydrogen chloride vapors and most of the vapors of the chlorinated benzenechemicals used or manufactured at the Metachemplant are heavier than air; therefore, in the eventof another release, the concentrations will behigher closer to the ground. If another spill orrelease occurs at the Metachem site while theOxyChem ball field is being used, the ball fieldshould be evacuated immediately. Particularattention should be placed on evacuating any children who are present as quickly as possible. Theentire plant area and the soil and sediment outside of the Metachem fence to the north and westof the plant are a health hazard because of contamination with site-related contaminants, so thatchildren 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 thesite and cancer, diabetes, autism, and obesity.


There is no scientific data to support the allegation that the chemicals used or manufactured byMetachem could cause obesity. In fact, if sufficient exposure to any of the chemicals fromMetachem (see Table 12) occurs, it could cause weight loss due to nausea, diarrhea, andvomiting.


ATSDR found no scientific data to support the allegation that the chemicals used ormanufactured by Standard Chlorine or Metachem cause autism.


ATSDR did not find any data that indicate that exposure to the chemicals manufactured by orreleased 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 chemicalsis not likely to occur in the communities in New Castle County. However, benzene is a chemicalknown to cause leukemia in humans. Because the community is concerned about cancer, ATSDRlooked at the cancer incidence rates for all types of cancer in Delaware compared to the rates forthe general U.S. population. According to the data published by the Delaware Department ofHealth and Social Services' Epidemiology Branch, from 1980 to 1998 the age-adjusted incidencerates 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 declinedbetween 1995 and 1998 (40). See Figure 6. Delaware is in a very industrialized area of thecountry, so that it is not possible to identify a single cause or industry that might be responsiblefor the higher cancer incidence rate in Delaware. For more information on cancer rates inDelaware, see the Delaware Division of Public Health Web site at

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