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Past gas manufacturing activities at the former Merrill Gas Company, in Lincoln County, Wisconsin, left behind substantial environmental contamination, particularly in sediments of the adjacent Wisconsin River. Coal tars in affected river sediments are regularly released and pose a health concern for people who touch them. One-time contact with a coal tar can cause skin and eye irritation and increase sensitivity to sunburn. Actions should be taken to prevent people from coming in contact with coal tars in river sediments. Warning signs should be placed along the river bank to warn people about the contamination. Remediation activities at this former MGP site should include measures to control and monitor air emissions.


The former Merrill Gas Company is on the current Lincoln Wood Products facility, which is along the Wisconsin River, in the city of Merrill, Lincoln County, Wisconsin. In May 2000, the first phase of an environmental investigation was conducted to determine the degree and extent of contamination in subsurface soils, groundwater, and river sediments on and adjacent to the Lincoln Wood Products property that is attributed to past manufactured gas plant (MGP) operations (1). Subsurface soil samples were collected at five soil boring points on the former MGP site. Laboratory analysis of the soil samples found elevated concentrations of diesel range organic compounds (DROs) and polycyclic aromatic hydrocarbons (PAHs) in subsurface soils. However, no one comes into contact with soil at the depth that was sampled; therefore, contact with subsurface soil is not discussed further. If the soil is remediated, then people living near by could be exposed to contaminants released into the air when excavation occurs.

Groundwater samples were collected from six groundwater monitoring wells and four hand-driven, sand-point wells. Analysis of groundwater samples found elevated concentrations of PAHs and volatile organic compounds (VOCs), with several VOCs and PAHs above their respective Wisconsin Groundwater Quality Public Health Enforcement Standards and Agency for Toxic Substances and Disease Registry (ATSDR) comparison values (2). No one is using contaminated groundwater for any purposes; therefore, contact with contaminants in groundwater is not discussed further.

Field observations of sediments were recorded at 15 boring locations, situated at five-foot intervals and along six different transects that ran perpendicular from the shoreline of the Wisconsin River. Observers reported "heavy-to-light sheens and petroleum-like odors" at five of these sediment boring locations. Sediment samples were collected at nine boring locations to a depth of 18 inches. Elevated VOC and PAH concentrations were detected in eight of the sediment samples, with the highest concentrations measured in samples where oil-like sheens and petroleum odors were observed. Although higher levels of VOCs and PAHs were found, all levels were below those associated with noncancer effects if contaminants were to be ingested or inhaled. However, even small amounts of coal tar products that get on the skin can increase a person's sensitivity to sun and could cause serious sunburn. Small amounts of coal tar products can also cause eye irritation. Therefore, contact with contaminated sediments is evaluated further.

On November 15, 2000, representatives of the Department of Natural Resources (DNR), Lincoln County Health Department, and Department of Health and Family Services (DHFS), visited the property. Former Merrill Gas Company buildings are on the northwest corner of the Lincoln Wood Products property and are approximately 100 to 200 feet from the eastern bank of the Wisconsin River. Employees of Lincoln Wood Products park their vehicles on a lot that is south of the former MGP buildings and west of the other buildings on the property. During the site visit, the air temperature hovered near freezing, the ground was hard but not thoroughly frozen, and a very narrow and thin layer of ice had formed along the shoreline. Across the Wisconsin River, staff could see Ott's Park, which has a picnic area and boat ramp, but it has no swimming beach. People regularly fish from boats and wade along the Wisconsin River, including stretches of the river in Merrill. The river bottom along the shoreline of the Lincoln Wood Products property are mostly sandy, with small areas of silt. Agency staff walked through the vegetated areas along the river bank and did not notice any indication of contamination or disturbed soils. The DHFS representative waded in shallow water along the shore, where the bottom was mostly sandy, with dark organic matter at several locations. At several locations, gas occasionally bubbled from the sandy bottom. At times, the bubbles deposited an oily film on the water's surface. This oily film had the distinct coal tar odor of petroleum and naphthalene. At those locations, staff used a stick to prod the bottom and observed additional gas bubbles that deposited an oily, coal tar-type, non-aqueous phase liquid (NAPL) on the surface. This action also produced a coal tar odor of petroleum and naphthalene. A sheen on the surface of the water resulted from staff wading through shoreline sediments at other locations.

DNR informed DHFS of an anecdotal report from a warden who had heard about an adolescent who, while wading along this shoreline several years ago, disturbed sediments and had direct skin contact with an oily sheen. Although the report was unclear whether this individual was fishing, anglers commonly wade in the river and wear only shorts or a swimsuit during warm weather. The warden had heard that shortly afterwards the adolescent's skin became substantially irritated and inflamed. The warden did not personally observe the injury but was given the information some time after the incident occurred from a relative of the adolescent. DNR was not able to locate any written reports of this alleged incident. The person who reported the incident to the warden reportedly wished to remain anonymous.


Past MGP activities at the former Merrill Gas Company have apparently left behind substantial environmental contamination. While shallow groundwater at several locations has a number of VOCs and PAHs that are well above the Wisconsin enforcement standards, no one is drinking this water. There are no known nearby drinking water wells that are impacted or threatened. Subsurface soils have elevated concentrations of certain PAHs. The subsurface soil sample with the highest observed PAH concentrations (SB-2) might be a concern if people had daily, unlimited contact for many years. However, a health concern does not exist because the contaminated soil sample was collected from a depth of 3 to 5 feet. Sediment samples have elevated concentrations of PAHs and VOCs, but none were at a level of health concern.

Although the highest concentrations of PAHs and VOCs that were measured in sediments are not at levels that might be a human health concern, the presence of coal tars/NAPLs in sediments that are released into water is of concern for anyone who has direct contact with the coal tar. People who wade, swim, or play in water along the riverbank of the former Merrill Gas Company unknowingly can come in contact with coal tars/NAPLs released from disturbed sediments. Regular skin contact with PAHs that are typically present in coal tars/NAPLs can increase a person's lifetime risk for certain skin cancers, but people are unlikely to regularly allow their skin to become coated with coal tars. Additionally, oily coal tars/NAPLs are strong dermal irritants that can be readily absorbed. A single instance of direct contact with coal tars/NAPLs can cause dermal inflammation and heighten a person's sensitivity to sunburn. A person with coal tars on their hands can easily rub their eyes, resulting in severe eye irritation. The symptoms of skin inflammation that were reported for the adolescent who waded at this location are consistent with other reported cases of direct contact with coal tars (3). The ATSDR toxicological profile on creosote also addresses aromatic mixtures that includes coal tars and summarizes that coal tar product "exerts its acute toxic effects in humans primarily via dermal contact, causing structural damage to the tissues that it comes in contact with, such as the skin and eyes," and that "animal studies corroborate these observations." Also this toxicological profile reported that "longer periods of dermal exposure to coal tar products seem to be associated with dermal irritation and noncancerous lesions, and skin cancer in both humans and animals (4)."

Actions are needed to prevent people from coming in contact with coal tars/NAPLs released from sediments along the river bank of the former Merrill Gas Company. An interim intervention should be to place warning signs at regular intervals on the river bank and adjacent to affected sediments so that unsuspecting people are alerted about the contamination. The signs should face multiple directions so that both boaters and people on land will be aware of the contaminated sediments and the need to avoid touching coal tar/NAPL slicks. The signs should also provide instructions that those who get tar on their skin should wash immediately with plenty of soapy water and avoid exposing affected skin to sunlight. Agency staff agree that the signs posted along the lakefront at Kreher Park, in the city of Ashland, are a good example of the appropriate health risk messages that should be communicated.

Posting signs is an interim public health intervention because people can still come in contact with contaminated sediments. Undisturbed sediments will also continue to release coal tars/NAPLs, which can float away and come in contact with people at downstream locations. Consequently, contaminated sediments should be cleaned up as a permanent intervention. Remediation activities at any former MGP site need to be carefully planned in order to control and monitor air emissions. A number of constituents of MGP waste are volatile and can escape into the atmosphere whenever contaminated groundwater, soils, sediments, or wastes are uncovered. Air emissions have been problematic at other MGP sites that have undergone remediation. Certain contaminants related to MGP sites, such as naphthalene, can be released into air at safe levels but cause strong odors. Nearby residents and businesses should be informed prior to starting remediation actions. In addition to air monitoring and on-site control measures, MGP remediation actions implemented during winter months can be an effective air management strategy because low air temperatures can minimize the air release and dispersal of odors and volatile compounds. Also, during winter months, people who work or live nearby have lower airborne exposures because they tend to spend less time outside and keep windows closed.


DHFS recognizes that children are especially sensitive to exposure to some contaminants. At the former Merrill Gas Company property, children who walk in or play along the river bank with impacted sediments are at risk of exposure to high levels of coal tars present in sediments. Children can have a greater exposure than adults because they typically play outside for longer periods and are attracted to playing in water, resulting in a greater duration of a single exposure than adults. Children also have a two-to-three times greater ratio of body surface area by body weight than adults (5), so a similar dermal exposure can have a heightened effect on a child.


Past manufactured gas activities at the former Merrill Gas Company have left behind substantial environmental contamination that poses a public health hazard for anyone who has direct skin contact with coal tar. One-time contact with a coal tar can cause skin and eye irritation and increase sensitivity to sunburn.

  1. Even though analysis of sediments did not find other contaminants at levels that pose a human health concern, coal tars are present in sediments and are regularly released into water as an oily film. A permanent intervention should be implemented to prevent people from contacting the coal tars in sediments.

  2. Hazard warning signs should be placed along the river bank as an interim intervention to warn people about the contamination.

  3. Remediation activities at this former MGP site should include measures to control and monitor air emissions.


  1. DHFS will continue to work with the Lincoln County Health Department to evaluate the human health implications of possible exposures at the former Merrill Gas Company Site.

  2. DHFS will work with the DNR and Lincoln County Health Department to ensure that the affected river bank is properly posted with warning signs.

  3. DHFS will continue to work cooperatively with DNR and Lincoln County Health Department on remediation activities at the former Merrill Gas Company Site, particularly to ensure that any emissions are appropriately controlled and monitored.

  4. DHFS will provide health education about the former Merrill Gas Company Site to nearby residents and workers.


  1. Gannett Fleming, Inc. Investigative Status Report and Work Plan for Second Phase of Site Investigation, Lincoln Woods Products, Merrill. BRRTS No. 02-35-000028. File #26871.000. Submitted to Charles Weister, Wisconsin DNR. Madison, WI: Gannett Fleming. October 27, 2000.

  2. Wisconsin Administrative Code. Chapter NR140. Groundwater Quality. March 2000.

  3. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Polycyclic Aromatic Hydrocarbons. Atlanta, GA: ATSDR. August 1995.

  4. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Wood Creosote, Coal Tar Creosote, Coal Tar, Coal Tar Pitch, and Coal Tar Pitch Volatiles. Update - Public Comment Draft. Atlanta, GA: ATSDR. September 2000.

  5. U.S. Environmental Protection Agency. Exposure Factors Handbook. EPA/600/P?95/002Fa. Office of Research and Development. Washington, DC: U.S. EPA. August 1997.


Henry Nehls-Lowe, MPH
Bureau of Environmental Health
Division of Public Health
Wisconsin Department of Health & Family Services


This public health consult on the Former Merrill Gas Company site was prepared by the Wisconsin Department of Health and Family Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health consultation was begun.

Gail D. Godfrey
Technical Project Officer, SPS, SSAB, DHAC

The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.

Lisa C. Hayes

Table of Contents The U.S. Government's Official Web PortalDepartment of Health and Human Services
Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

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