HEALTH CONSULTATION
(A DuPont Barksdale Dynamite Plant Operation)
FORMER DUPONT CLADDING SITE AT CABIN LAKE
(a/k/a DUPONT BARKSDALE EXPLOSIVES PLANT)
WASHBURN, BAYFIELD COUNTY, WISCONSIN
The Wisconsin Department of Health and Family Services (DHFS) evaluated soil sampling data from the former DuPont cladding site near Cabin Lake, in Bayfield County, Wisconsin. Explosive and inorganic compounds detected in soils were very low and pose no apparent public health hazard. Given the low levels of contaminants in soils, meat from deer or other animals found at the site is safe for people to eat. Investigations at the Cabin Lake site were limited in scope. DHFS recommends discussion between the Department of Natural Resources (DNR) and E. I. DuPont de Nemours and Company (DuPont) about the need for additional investigations. DHFS will continue to evaluate new sampling data that may come from the Cabin Lake site. DHFS will also continue to coordinate with Wisconsin DNR and Bayfield County Health Department in addressing environmental health and public health issues that pertain to the former DuPont properties and communities in Bayfield County.
Since 1995, DHFS staff have been involved with public health evaluations of environmental contamination at the former DuPont Barksdale Works, in Bayfield County, Wisconsin. DuPont manufactured explosives at the 1,800-acre Barksdale plant site from 1905 to 1971. During discussions with the community and other agencies, DHFS received anecdotal reports that DuPont also conducted metal cladding operations at a remote location near Cabin Lake, within the Chequamegon National Forest. Citizen reports to DHFS included descriptions that the former DuPont cladding site near Cabin Lake is devoid of vegetation because wildlife continuously dig and ingest surface soils at the site. Several community members said the site was a good place to hunt because deer are attracted to something in the soils. DuPont also reported it previously conducted metal cladding operations at Cabin Lake. Explosive metal cladding is an industrial process that fuses different types of sheet metal using high explosives.
On the morning of May 25, 2001, staff from DHFS and DNR visited the Cabin Lake site. When walking onto the site, staff saw several deer fleeing from an approximately 3-4 acre clearing into the forest. A large portion of this clearing had little or no vegetative cover. In some locations, surface soils were loose and completely covered with deer hoof prints. These hoof marks were made since morning, when it had rained. Deer had apparently dug with their hooves down to deeper soils at a number of locations, with the deepest holes being 2-3 feet deep. Pieces of metal debris and short lengths of wires were randomly dispersed in soils across the property. Metal and wood debris protruded from the walls inside several holes, suggesting these soils were previously disturbed by human activities. During the site visit, agency staff saw a deer return to the open area of the site, walk into a dug depression, stop, and regularly lower its head, apparently ingesting soils.
On July 11, 2001, DHFS and DNR staff returned and collected soil samples from the Cabin Lake site. Six surface soil samples were collected from selected locations, including inside and near points that were dug by wildlife. These samples were submitted to the Wisconsin State Laboratory of Hygiene and analyzed using U.S. Environmental Protection Agency Method 8270C. This method targets 68 semivolatile organic compounds, including the two most common isomers of dinitrotoluene (2,4- and 2,6-dinitrotoluene). Trace amounts of di-n-butyl phthalate were found in soil samples. Di-n-butyl phthalate was also detected at similar concentrations in the laboratory blank, suggesting the compound was a laboratory artifact and not actually present in soils at the site (1).
On August 14, 2001, DuPont staff visited the Cabin Lake site and collected surface and sub-surface soil samples from 10 locations. These samples were analyzed for nitroaromatic and nitramine organic compounds, inorganic compounds, semivolatile organic compounds, and volatile organic compounds. DuPont reported their findings in September 2003 (2). These results are summarized in Table 1. DuPont concluded that none of the compounds found were "a threat to human health."
Table 1. Surface Soils Sampling, August 2001, Former DuPont Cladding Site at Cabin Lake, Bayfield County, Wisconsin. All Concentrations in Milligrams per Kilogram (mg/kg)
|
|
Highest Level Detected | Lowest Level Detected | Frequency of Detection |
Health Comparison Value |
| Explosives | ||||
| 2-amino 4,6-dinitrotoluene | 0.19 | 0.039 | 4/10 | 21.0* |
| 2,4-dinitrotoluene | 0.11 | - | 1/10 | 100.0† - child 1,000.0† - adult |
| 2,4,6-trinitrotoluene | 0.016 | - | 1/10 | 100.0† - child 1,000.0† - adult |
| Inorganic | ||||
| Copper | 411.0 | 8.1 | 10/10 | 2,000.0 ‡ - child 20,000.0 ‡ - adult |
| Lead | 114.0 | 6.3 | 10/10 | 400.0§ |
* U.S. Environmental Protection Agency's Region III Provisional
Health Value.
† Agency for Toxic Substances and Disease Registry's Chronic
Environmental Media Evaluation Guide.
‡ Agency for Toxic Substances and Disease Registry's Intermediate
Environmental Media Evaluation Guide.
§U.S. Environmental Protection Agency's Residential Soil Cleanup
Guideline for Lead.
DHFS concludes that the contaminants found in soils at the former DuPont cladding site at Cabin Lake pose no apparent public health hazard. Table 1 shows the results of the DuPont investigation and corresponding health-based environmental comparison values used by DHFS in evaluating the public health implications of the detected compounds. DHFS's conclusion is based on the fact that all detected explosive compounds were less than the lowest, human health-based comparison value. Lead and copper were also detected in samples from all locations, but at levels typical of those found in soil at this location and below levels associated with health effects.
People have asked DHFS whether wildlife that eat soils at the Cabin Lake cladding site may contain elevated levels of explosive contaminants. They then ask whether meat from this game is fit for human consumption. It is evident that deer and other animals are ingesting soils at the Cabin Lake site. Nitroaromatic explosive compounds do not bioaccumulate nor persist in animal tissues (3). These chemicals, when ingested by people or animals, are rapidly excreted through urine or feces. Given the low levels of contaminants found at the site, and their tendency not to accumulate in animal tissue, meat from deer or other animals at the site is safe to eat.
From the reported history of the cladding site at Cabin Lake, the presence of physical debris, and chemical residual contamination, it is apparent that past industrial operations have left environmental effects. Available sampling data did not reveal levels of contamination that would be of concern to human health, but the investigations were limited in scope. DHFS recommends further discussion between DNR and DuPont on whether there is a need for additional investigation of other environmental media at the Cabin Lake site.
Contaminants found at the former DuPont cladding site at Cabin Lake pose no apparent public health hazard to children who may regularly visit and play there. DHFS includes children when evaluating exposures to contaminants and considers children as the most sensitive portion of the population that was evaluated in this public health consultation. Additionally, DHFS considered that children may live near or regularly visit the former DuPont cladding site at Cabin Lake. The Cabin Lake site is remotely located within the Chequamegon National Forest, with the nearest home several miles away. Given the low accessibility of the Cabin Lake site to young children, any potential child health risks are much less than for a site in a residential or urban setting.
DHFS recommends that DNR further evaluate how people use the Cabin Lake site to determine whether other environmental media should be sampled.
Henry Nehls-Lowe, MPH
Epidemiologist
Bureau of Environmental Health
Division of Public Health
Wisconsin Department of Health and Family Services
This Former DuPont Cladding Site at Cabin Lake health consultation 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 Godfrey
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this health consultation and concurs with the findings.
Roberta Erlwein
Chief, SPS, SSAB, DHAC, ATSDR
