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The 5-acre Silresim site is in Lowell, Massachusetts, and was previously the location of a chemical waste reclamation facility. A total of 132 chemicals have been detected on site and in the surrounding 60-acre study area. Groundwater and soil (surface and subsurface) are contaminated primarily with volatile organic compounds (VOCs) and metals. Low levels of polynuclear aromatic hydrocarbons (PAHs), dioxins/furans, polychlorinated biphenyls (PCBs), and pesticides have also been detected. VOCs, amines, phenols, and dimethylformamide (DMF) were detected in the ambient air during the various studies. Generally, the concentrations of ambient air contaminants did not differ significantly between samples collected in the site vicinity and background samples collected throughout the city.

A descriptive epidemiologic study was conducted by the Massachusetts Department of Public Health (MDPH) as part of this health assessment. Available cancer incidence data were examined for the city and for census tracts within a one-mile radius of the site. Incidence rates were calculated for cancers of the bladder, liver, lung, and prostate, as well as for soft tissue sarcoma, leukemia, Hodgkin's disease, and non-Hodgkin's lymphoma (NHL). Within the one mile radius, significant elevations in lung cancer were observed in men and women in several areas, and an apparent elevation in liver cancer was observed in one area. However, the liver cancer cannot be assigned any statistical significance due to the small number of cases. Examination of occupational and smoking status information from MDPH's cancer registry indicates that life-style factors may have played a role in the lung cancer cases.

Populations with the greatest potential for past exposure to contaminants originating from the site are the company's workers, workers in neighboring facilities, children who might have played on site or in the study area, and nearby residents. Past exposure pathways of particular concern are: (1) occupational exposure of the on-site workers primarily through inhalation and dermal absorption; (2) ingestion and inhalation exposures of children who might have played in the study area; and (3) inhalation exposures of nearby workers and residents. Although past exposures most likely did occur, the chemicals and dosages are difficult to determine due to the lack of monitoring data before the interim remedial activities.

Current exposures and potential health impacts are limited because of the interim remedial measures, fencing and capping of the site, and site security. EPA has investigated the groundwater plume to determine if the volatilization of contaminants into the basements of nearby structures is a current or future concern. The groundwater plume has not reached the residences around the site and therefore, residents are not being exposed to site related contaminants via this route. The potential for other effects during or following remediation activities will be assessed once additional information is available, and the health assessment will be modified by amendment if warranted. Based on the available information, this site represents no apparent public health hazard.

The Public Health Assessment for the Silresim Chemical Corporation site, Lowell, Massachusetts, has been evaluated by ATSDR's Health Activities Recommendation Panel for appropriate follow-up with respect to health activities. The Panel determined that community health and physician education are indicated. No health studies are indicated at this time. The MDPH will conduct public meetings upon request to educate residents and workers in the site vicinity about the exposure pathways and adverse health effects potentially associated with the chosen remeditation. The MDPH will send a follow-up letter to the residents of the house where the contaminated private well is located. This letter will emphasize the historical contamination of the private well and remind the current residents that the well should not be used for drinking water purposes. The MDPH will conduct health professionals education in relation to the site.


A. Site Description and History

1. Site Location and Current Physical Appearance

The Silresim National Priorities List (NPL) site at 86 Tanner Street in Lowell, Middlesex County, Massachusetts, is about 25 miles northwest of Boston (figure A-1). The site was placed on the U.S. Environmental Protection Agency (EPA) Proposed NPL in December, 1982. The site is the location of the former Silresim Chemical Corporation, which operated as a chemical waste reclamation and disposal facility from 1971 to 1977. Currently, the site is an approximately 5-acre area enclosed by a chain link fence topped with barbed wire. The EPA study area, however, extends beyond the actual site to include approximately 60 acres.

Within the site boundaries are the following areas of concern:

    1. A water purge tank, a work-staging area, a storage trailer, several empty 55-gallon drums, and a pile of crushed stone have been on site as of November 1991; work was performed on site in November 1990. There are no permanent structures currently on site.

    2. Ten PVC riser pipes extend from a venting system below the clay cap to approximately 2 feet above the cap surface. Carbon filters are attached to each of the vent openings. According to EPA, the filters are old and probably saturated. However, based on vent sampling results (November 1986) and the air flow rates within the vents, EPA determined that it was not necessary to filter the vent emissions [55].

    3. Although the site topography is generally level, the clay cap covering most of the site elevates it approximately 3 feet above the surrounding ground level. Erosion of the cap has occurred due to a lack of a drainage blanket or an organic topsoil layer [21,55]. Adverse effects of erosion, such as washed-out gullies in the clay surface, sediment in the clay cap drainage system, discharges of sediment to the River Meadow Brook, and pooling of runoff on the property north of the site have been observed in the past [56]. Based on site conditions, it does not appear as if the cap erosion has resulted in the generation and migration of contaminated fugitive dusts around the site. Generally, the DEP is responsible for cap maintenance and has overseen some cap repairs in the past. However, following sampling activities in 1991, the EPA completed limited repairs to the more deeply rutted areas of the clay cap.

    4. A small triangular section of the northeast corner, where the Boston and Maine Railroad tracks cross the site, is covered with crushed stone. Crushed stone has also been placed in certain areas outside the site fence in an attempt to stabilize the clay cap erosion and to cover areas of surface soil contamination.

Bordering the site are the following properties (see figure A-2): (1) the Lowell Iron and Steel property to the north, (2) Boston and Maine Railroad tracks to the east, (3) Lowell Used Auto Parts to the south, (4) the River Meadow Brook and industrial property across Tanner Street to the west, and (5) residential areas to the south, east, and northeast of the site on Canada, Maple, Autumn, and Main Streets approximately 300 to 500 feet from the Silresim perimeter fence. A pond and a wetland area are east of the site, between the perimeter fence and the residential areas.

2. Site History and Remediation History

a. Operational Activities

The Silresim Chemical Corporation was established in 1971 as a chemical waste reclamation facility and was granted a hazardous waste collection and disposal permit by the Massachusetts Department of Water Pollution Control (DWPC) in 1973. The facility was involved in the collection, hauling, storage, laboratory analysis, processing, off-site incineration, recycling and disposal of industrial chemical wastes throughout New England, New York and New Jersey [21-23,44]. Distillation towers, an evaporation system, an oil separator, and ancillary equipment were used for the various processes [18,20,21]. According to EPA records, a fractionization column was on site but was never used because of a lack of proper permits. In 1978, fire gutted one laboratory building, thereby making this building inaccessible [2,13-15,17,23,61].

Silresim owned a fleet of trucks for the collection and hauling of both bulk and drummed waste. Unloading facilities consisting of 530,000 gallons of total tank storage capacity were on site. The chemicals were recycled or converted to forms suitable for disposal by off-site incineration or landfilling [21-23]. Silresim maintained eight systems to handle the treatment of a number of hazardous wastes. Wastes that could not be treated or recovered were stored on site and reportedly transported to another treatment facility that could handle the wastes. Silresim also maintained a 50,000-gallon inventory of waste oil, which was used as fuel to generate steam. Before ceasing operations in 1978, Silresim had received and recycled a variety of chemicals, including, but not limited to, halogenated organic solvents, oil wastes, cyanide solutions, metal sludges, and pesticide wastes [21,22,44]. Refer to Appendix B for a more comprehensive list of chemicals and products found on site in 1978.

Some of the known waste storage and disposal practices at Silresim are summarized in the following sections. For additional information, refer to the EPA letter regarding an inventory of hazardous waste management facilities and the report by Fred C. Hart Associates Inc. [13,24].

b. Site Regulatory History

Between 1973 and 1976, Silresim was cited for various permit violations because the volume of on-site waste began to exceed the storage/recycling capacity of the facility. A site inspection in October 1975, revealed site deterioration and non-compliance with previous recommendations. This situation led to the issuance of a new permit in 1976, which limited the quantities and types of waste handled by Silresim. The facility contested the permit modifications, which were subsequently lifted in April 1976, on the condition that a compliance schedule for site cleanup and improved operations be established.

During October 1976, the bank which held the mortgage on Silresim decided to close the facility. However, after determining that the property was a net loss, the bank ordered the removal of the drums and allowed the facility to re-open. According to the Hart report [23], state inspectors surmised that Silresim emptied the drums into storage tanks on site and then discarded the emptied drums under its permit, which allowed removal of an average of 1,000 drums per month. DWPC staff observed the following conditions on site, which give an indication of the waste storage and disposal practices: (1) extensive and repeated spills of materials (i.e., oils, solids, and sludges) over the grounds and equipment; (2) drums, stacked vertically up to four high, were leaking, corroded, split, and ruptured; (3) materials were flowing, or showed evidence of flowing, onto adjacent properties; (4) lack of on-site facilities for treatment of runoff or process discharge; and (5) foul chemical odors throughout the site.

In July 1977, due to further non-compliance, DWPC initiated action to close the facility. Throughout the fall of that year, various permit violations at Silresim included, but were not limited to, these: 1) discharging of VOCs into the sewer system, and 2) acceptance of pesticide wastes.

c. Remediation History

Silresim declared bankruptcy in December 1977, and the state hazardous waste collection and disposal permit was revoked. After the property was abandoned in January 1978, the DEP erected a chain link fence around the site and hired 24-hour security in order to prevent access to the site and limit exposure.

During March 1978, DWPC hired Coastal Services Inc. to perform interim containment measures on site. Berms and absorbent-filled trenches were constructed to alleviate surface runoff and to attempt to prevent further spreading of wastes to adjacent properties. In December of that year, Newco Chemical Systems Inc. began to remove and dispose of all drums and tanks on site. Clean-up activities were halted in 1980 due to a shortage of available funds. Site cleanup was completed in 1981 by Jet-Line services under a bond approved by the state legislature for hazardous waste cleanup.

Perkins-Jordan Inc. completed a Hydrogeologic Investigation (HI), a Remedial Action Study, and an Addendum to each of those studies between February 1982 and March 1983 [44-47]. The reports concluded that extensive remedial action was not warranted and that air emissions, not the groundwater plume, would have the largest effect on receptor sites. Perkins-Jordan concluded that a clay cap was the most effective technique for reducing air emissions and preventing infiltration, thereby decreasing the contaminants' effects on local receptors.

In December 1982, Silresim Chemical Corporation was placed on the EPA National Priorities List (NPL). A Remedial Action Master Plan was completed in April 1983. The Interim Remedial Measures (IRMs) consisting of the demolition of existing buildings and aboveground tanks at the site [8] was an EPA lead activity. All work was performed by EPA contractors. The site was graded, covered with gravel, and a clay cap was installed in December 1984 as part of the IRMs.

The various phases of the Remedial Investigation/Feasibility Studies (RI/FS) were conducted during the period from 1986 to 1988 to address various on- and off-site contaminant concerns. During the initial stages of Phase I, dioxin-contaminated soil was discovered at the southeastern corner of the site [44]. As a result, EPA expanded the fence line to enclose the area of dioxin contamination. EPA contractors subsequently placed a 6- to 8-inch-thick layer of crushed stone for 10-20 feet around the perimeter of the expanded fence line to limit potential exposure to surface soils in that zone. A supplemental Remedial Investigation was conducted in June 1991 to determine the extent and distribution of dense, non-aqueous phase liquids (DNAPL) in the bedrock and overburden aquifers.

EPA released the draft report on proposed remedial actions in June 1991. An EPA Record of Decision (ROD) for the site was signed on September 19, 1991.

B. Site Visit

On November 20, 1990, a site visit was conducted at the Silresim Chemical Corporation site by two MDPH Environmental Analysts (Anne Fox, William Strohsnitter) and the EPA Remedial Project Manager. During the course of the site visit, the current site status (interim remediation activities and evidence of transport mechanisms) and appearance (physical hazards and security) were noted. Interim remediation techniques that were inspected consisted of:

  • The integrity of the clay cap and air venting system.

  • The gravel and crushed stone barriers in the northeastern and southeastern corners of the site and in certain areas around the perimeter fencing.

Other observations included the presence of the grass lawn covering the clay cap, the location of River Meadow Brook and East Pond, the location of nearby businesses and residences, the grading of the site, and the overall maintenance of the site. Within the vicinity of nearby businesses, there were strong chemical odors on the day of the site visit. The physical hazards and site-security observations are presented in the "Environmental Contamination and Other Hazards Section."

Site conditions have changed since the 1990 visit. Currently, remedial activities are ongoing and a air monitoring system, with alarm, has been installed.

C. Demographics, Land Use, and Natural Resource Use

1. Demographics

The Silresim Chemical Corporation site is in the south central section of Lowell, one mile north of Chelmsford, 2 miles east of Tewksbury, and approximately 2.25 miles south of Dracut. The 1980 U.S. Census indicated that 92,418 individuals live within the city of Lowell. The closest residences are approximately 300 to 500 feet to the south, east, and northeast of the site perimeter fence on Canada, Maple, Autumn, and Main streets [44].

The cities of Lowell, Lawrence, and Methuen obtain their drinking water from the Merrimack River. The intake for the Lowell Water Utility is 3.5 miles upstream from the confluence of the Merrimack and Concord rivers. The intake areas for Lawrence and Methuen are 8.5 and 7.5 miles downstream from the confluence of the two rivers, respectively [23,44,51]. According to DEP/DWPC records, more than 100,000 people obtain their potable water from the Lowell Water Utility System [31].

Eleven schools in Lowell (Ames School, Butler Junior High School, Cardinal O'Connell School, Eliot Alternative School, Laura Lee School, Lincoln School, Molloy School, Morse Street School, Rogers School, Sacred Heart School, and St. Stanislaus School) are within a one-mile radius of the site. The Laura Lee School is a public pre-school for special needs students. The Eliot Alternative School is also a special-needs school for students with behavioral disorders [52].

There are no hospitals within a one-mile radius of the Silresim site. St. John's and St. Joseph's hospitals in Lowell are both within a two-mile radius of the site. Of the 12 nursing homes within the city of Lowell, only one is within one mile of the Silresim site. Four of the five elderly housing complexes within the city are also within one mile of the site. In Lowell, there are 51 multiple-unit family housing projects and two mixed (elderly and family) multiple-unit housing projects. Thirty-five multiple-family projects and one multiple-unit mixed project are within one mile of the site [48,50].

2. Land Use

Currently, the Silresim site is fenced to prevent access by unauthorized personnel. It has been reported that children have used the area near the railroad tracks as a shortcut walkway and the pond to the east of the site as a recreational area [16,24]. Neither the railroad tracks nor the pond are within the site fence, but both are included in the study area (see figure A-2). Land use near the site is a mixture of residential and commercial/industrial. A variety of industrial activities are practiced near the site, including metal processes (engraving, plating, and fabrication) and auto repair/salvaging. River Meadow Brook is immediately west of this industrial area. The Boston and Maine Railroad tracks are east of the site, and undeveloped wetland is situated beyond the railroad tracks. Within the Department of Environmental Protection (DEP) "List of Confirmed Disposal Sites and Locations to be Investigated, March 1990," many DEP sites are listed within a mile of the Silresim site [37]. The four DEP sites closest to Silresim are Astro Circuits to the north on Hale Street; Brady Business Forms and "Property" to the northeast on Lincoln Street; and Gas Station and Oil Company to the south on Main Street.

3. Natural Resource Use

The City of Lowell has obtained municipal water from the Merrimack River since 1960. The Lowell Water Utility also provides water to approximately 75% of the town of Dracut, 35% of the town of Tewksbury, and to less than one percent of residents in the town of Tyngsboro [51]. Treated surface water from the Merrimack River is pumped to an intermediate capped reservoir in the Christian Hill Section of Lowell, approximately two miles northeast of the site. Water flows from the reservoir throughout Lowell via gravity [51]. Lowell's pumping station supplied water to approximately 130,000 persons in Lowell, Tewksbury, Tyngsboro, and Dracut at an average rate of 4,917.2 billion gallons per year for the years 1980-1990.

According to the Superintendent of Lowell Water Utility, the only private well near Silresim is at the Lowell Car Wash on the corner of Plain and Tanner Streets. This well supplies process water for the car wash and is not used as a potable water source. Historically, one private well was on Main Street near the Silresim site. That well was installed primarily for gardening purposes; however, the residents stated that they were using the well as a source of potable water due to the cost of the municipal water supply. According to DEP and City of Lowell records, the well on Main Street was tested and several organic compounds were found, ranging in concentration from 1.7 to 72.0 parts per billion (ppb) [29,34,50]. In 1982, DEP and the Lowell Board of Health recommended that the well not be used as a source of potable water [29,34,50]. The private well on Main Street was removed in September 1986.

No other information is available for those two private wells (e.g., the installation depths or whether the wells were installed in bedrock or overburden). Although required by state law to report the installation of private domestic water supply wells to the local board of health, it should be emphasized that the ownership of such wells is self-reported, and that other wells may exist. Enforcement of the law by towns within the state is variable. Older private wells are not likely to be reported.

Fishing and boating are known to be recreational activities in some areas along the Merrimack and Concord Rivers. Swimming/wading by children is reported to occur in both River Meadow Brook and the East Pond. However, recreational activity is probably limited at East Pond for the following reasons: (1) the variable water level in the pond during warmer months; (2) the potential inaccessibility of the pond because of plant growth; and (3) various debris in the pond and surrounding area.

D. Health Outcome Data

Relevant health outcome data were obtained from the Massachusetts Cancer Registry. Cancer incidence data for the years 1982-1989 included types of cancer determined to be of concern based on the available scientific literature and community concerns. Analyses were made at the city and census tract levels. Population data were obtained from the regional office of the U.S. Census.


Community concerns about the Silresim site are evident: various groups are involved with site-related issues; numerous newspaper articles have reported on alleged health impacts, and a high volume of correspondence has been received by state and federal regulatory and health officials. Citizen and private-sector groups involved with the site, and their respective concerns, include these:

    1. Lowell Fair Share: Citizens from Lowell formed this group as a result of their concerns about possible health effects following exposure to Silresim site contaminants. The group is responsible for conducting an independent health survey to look at possible health effects in the Silresim area. Lowell Fair Share has also urged EPA to address various issues related to the Silresim site. Issues of concern to that group include the fencing and posting of the site to protect residents and others from contacting the site; removal of all tanks and drums from the site; and conduct of an in-depth health survey by contractors to determine the magnitude of health problems in neighborhoods around the site. Members of Lowell Fair Share in 1981 conducted a health survey of residents in the Silresim area in order to assess the extent of health problems they believed resulted from exposure to the site. The findings of that and several other studies are presented in the Health Outcome Data Evaluation subsection of the Public Health Implications section.

    2. Massachusetts Fair Share: This group is a state-wide organized coalition of advocates who advised and supported Lowell Fair Share at various times in order to urge state and federal governments to institute specific clean-up remedies for the Silresim site. Newsletters, door-to door canvassing, picketing, television appearances, and intensive lobbying were methods Massachusetts Fair Share used to gain support for their views.

    3. The Sacred Heart Parish: This loosely organized group of people from a parish approximately one mile east of the site worked closely with State Representative Edward LeLacheur. The main concerns of the group were health effects, economic impacts, and community image.

    4. The Silresim Task Force: This group was established in 1982 as a coalition of state and local officials and community representatives. The purpose of the task force was to improve communications between officials (both state and local) and residents regarding site activities. Massachusetts Fair Share, Lowell Fair Share, and the Sacred Heart Parish all had representatives on the Task Force.

    5. The Ayer City Homeowners Association: This group consists of residents living in the Ayer City section of Lowell, near the Silresim site. They worked closely with, and expressed concerns similar to, Lowell Fair Share and Massachusetts Fair Share.

Topics identified as being of particular public health concern include these: (1) the past, present, and potential future threat to public health due to site-related contaminants in the soil, air, and groundwater; (2) potential exposure to children who might play in the pond east of the site or in the brook west of the site; and (3) potential migration of contaminants into the Merrimack River, which is the drinking water source for the cities of Lowell, Lawrence, and Methuen.

Particular health issues have been reported in the local and Boston news media between 1981 and 1986. Many residents recount recurrent bouts with sore throats, skin irritations, ear infections, colds, bleeding, bronchitis, watery eyes, and headaches [10]. According to one report, within a seven-month period, two children had 13 double ear infections and 10 strep throats [11,39]. Another family reported two miscarriages, one child who died shortly after birth, and a woman with a blood-clotting disorder [11]. One child was taken to the hospital with what appeared to be chemical burns on his feet after running across a field near Silresim [5,24]. Several families stated that their health improved after authorities began to remove the chemicals from the site, or after they moved at the advice of their physicians [11,12,27,32,39,40,58,62]. Other news reports told of a resident and her daughter who were tested for PCBs and reportedly told that they had high levels in their tissue [62].

During preparation of this health assessment, a concerned parent contacted MDPH about a perceived elevated rate of Hodgkin's disease, non-Hodgkin's lymphona, and leukemia in children attending the Shaughnessy School in Lowell. Two cases of Hodgkin's disease and one case each of leukemia and lymphoma have been diagnosed since the Fall of 1990. Also, a former employee of Arrow Carrier contacted MDPH with a concern about elevated cancer rates in persons employed around Silresim during its time of operation. That employee was diagnosed with acute lymphocytic leukemia and knew of another former employee who also had cancer (colo-rectal).

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