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A complete exposure pathway consists of the following five elements: 1) a source of contamination (that is, a source from which contaminants are, or have been, released); 2) environmental media receiving contamination and transport mechanisms; 3) a point of exposure (a point of human contact with the contaminated medium or media); 4) a route of exposure (ingestion, inhalation, or skin contact); and 5) receptors (human(s) present at a point of exposure and in contact with contaminants). When one or more of the five elements are missing, a pathway is considered to be potential (for example, pathways which are not presently complete, but could become so under conditions which might reasonably occur). Pathways are eliminated from further consideration if one of the elements can be ruled out (for example, a human receptor is known not to exist at a point of exposure to contaminated media) or if exposure is improbable (for example, if zoning restricts drilling of wells).

A. Completed Exposure Pathways

1. Groundwater (private wells)

Before the 1980's contaminant movement off-site via groundwater was not measured. Therefore, it is unknown at what levels or for how long site contaminants may have been in groundwater near the site that was used for potable purposes. During ground-water monitoring from 1984-88, samples from shallow monitoring wells in residential areas downgradient of the site have contained cPAH, nPAH, and PCP at concentrations near or above federal and state drinking water advisory levels. Since wood-treating operations began at the Joslyn site in the 1920's, contaminant plumes have moved from the site. This is suggested by water quality surveys of the downgradient residential areas conducted by MDH in 1961 and 1979 (MDH 1990), in which phenol was found in some residential wells. PAHs were not tested for in groundwater before the RI.

Most residents in the area downgradient of the Joslyn site began receiving water from the municipal system in the early 1960's, but several were not supplied by that system until the late 1970's and early 1980's. A well search in the area downgradient of the Joslyn site in 1985 identified six wells used for potable water and thirty-seven residential wells used for nonpotable purposes such as lawn and garden watering. In most cases the depths of these residential wells could not be ascertained. The six potable well water supply systems were converted to municipal water in 1988. No action has been taken to investigate potential contamination of the remaining nonpotable residential wells, or to monitor their use.

Some of the nonpotable residential wells near the eastern and southern site borders were contaminated at low levels when last sampled in 1980. Nearby shallow monitoring wells have contained high concentrations of PCP (maximums of 950 µg/L to the east of the site, 180 to the south) and nPAH (maximums of 64 µg/L to the east, 46 µg/L to the south). Dioxins and furans found in the DNAPL, the floating-oil layer, and in shallow groundwater sampled from well U2 have also migrated off site: low levels of dioxins furans as well as PCP were detected in August 1990 groundwater samples from off-site monitoring wells (W122, W124, W125, and W128).

The results of the RI groundwater analyses did not indicate elevated levels of metals (arsenic, chromium, and copper) in filtered samples of groundwater. These samples may not be entirely representative of metal levels in residential wells if the wells do not allow similar filtereing to occur before water is used from the tap. In the filtered samples, none of these three metals exceeded their respective RAL. Metals, like dioxin and furans, are expected to be less mobile in groundwater than PCP and nPAHs. However, it is possible that these contaminants are also present in the nearby residential wells, because they have been detected at low levels in off-site monitoring wells and soluble metal salts were used for a short time at the site. Metals could also be present simply as naturally ocurring elements.

Owners of some 38 private wells downgradient of the site reported using groundwater for outdoor use. These wells may contain low-levels of site-related contaminants, particularly PCP and PAHs. The potential for these wells to intercept groundwater contaminants depends upon their locations and depths as well as the mobility of contaminants and direction of groundwater migration. Outdoor (nonpotable) use of contaminated water from residential wells in washing cars, watering gardens and lawns, filling children's swimming pools, or other outdoor activities may result in human dermal exposure or incidental ingestion and occasional drinking from the hose. To a lesser extent, there might also be some potential for dermal exposure via contaminated lawns or indirect exposure through ingestion of garden produce. Some low-molecular-weight PAHs are volatile or semi-volatile, so low-level inhalation exposure from outdoor water use is also possible.

2. Air

Fugitive dusts from stockpiled contaminated soils on-site may become airborne during soil handling and treatment. Contaminated dusts from the site may be inhaled by workers on site or by people downwind near the site. Dust monitoring at the site perimeter and in the breathing zone of remediation workers has not shown high levels of airborne dusts on site. Because measured levels of total suspended particulates (TSP) across the site did not frequently exceed national ambient air quality standards, and it is assumed that measurements of TSP overestimate PM10 (the fraction to which the standards apply), available monitoring data do not suggest that nuisance dusts are significant off-site. However, if contaminants are adsorbed to dusts, the occupational standards and the national ambient air quality standards for nuisance dusts may not be protective against harmful effects of exposure to the contaminants.

Volatilization of contaminants from any free product or highly contaminated materials may not be insignificant to persons in the immediate area; as shown by a 1991 air sample taken near an excavation of contaminated soil. Remediation workers exposed to the highly contaminated soils have reportedly used respiratory protection. Although air monitoring data for specific known site contaminants have not detected airborne contaminant levels of concern for occupational settings, sampling has been limited. These limited data do suggest that off-site levels are likely to be very low, although workplace standards are not appropriate comparison levels for the general population.

Contaminated groundwater is treated in the control building before discharge to the sanitary sewer. Although most of the contaminants found in groundwater at the Joslyn site are not highly volatile, volatilization of some of the low-molecular-weight PAHs (for example, naphthalene) may be considerable. Air samples from within the control building did not find significant levels of PCP, phenol or naphthalene in a 1991 sample, despite strong odors reported in the building.

B. Potential Exposure Pathways

1. Soil

Until remediation is complete, contaminated soil at the site provides a potential route for movement of contaminants to groundwater and air. The excavated soil is stockpiled on the site's surface atop a plastic liner and is covered with plastic. Stockpiled and excavated contaminated soil is thin spread on the ground surface in the LTU. Other small quantities of contaminated soil remain buried at depth.

The biological land treatment of contaminated soil will substantially lower the contaminant levels in the top 3 feet of site soil, and thereby decrease the levels of contaminants leaching from soil to groundwater. Leachate from soil is expected to be removed by the groundwater pump-out system. However, if contaminant leaching from treated soil is substantial, the MPCA may request that an impermeable cap be placed over the soil treatment area at closure.

Currently, the fence around the site prevents the general public from contacting contaminated soils stockpiled or spread in the LTU. While the fence is believed to be fairly effective in restricting site access, it should be fixed along the north side where it has been cut from the pole.

On-site staff working with the contaminated soil may be exposed to contaminants via dermal contact or incidental ingestion. Persons on- and off-site could also inhale fugitive dusts. Currently, measures are taken to minimize these potential exposures. On site staff who work with the soils wear protective clothing and respirators. Dust is controlled by sprinkling with water and by covering the stockpiled soils awaiting treatment.

After soil treatment goals are achieved by bioremediation, PAHs and PCP will still be present, but at much reduced levels. In addition, the low levels of metals, dioxins, and furans will not be removed by soil treatment. After treatment, soils will be covered with a three-foot cap of clean soil and vegetated. Assuming that the soil used in covering the treated soils does not is free of contaminants, and that the cover and treated soil are not disturbed, human exposure to remaining soil contaminants will be unlikely.

2. Surface Water/Sediments -- Shingle Creek

Shingle Creek, which runs north-south about 1 mile east of the Joslyn site, receives storm-water runoff from residential, commercial, and industrial areas. The creek may have received PAHs and PCP from the site via the Highway 100 drain-tile system in the past. Although the distance between the drain-tile system and Shingle Creek is large, high concentrations of PCP in the monitoring well closest to the drain-tile system (W112) indicate that in the past the drain-tile system may have diverted contaminated groundwater from the site into the storm-sewer system and then into Shingle Creek.

Sediments and waters of Shingle Creek may have been contaminated with PAHs and PCP from shallow groundwater that reached the drain-tile system in the past. As late as 1990, the levels of PCP and nPAHs found in the drain tile waters showed the presence of site contaminants. When the levels in the drain tile ditch were highest, the outfall and creek were not sampled. In 1991, 1992, and 1993, water samples from the creek (including upstream) and the drain system outfall showed no appreciable difference from levels of PCP, nPAHs, and cPAHs in the drain-tile system. The majority of samples from all three sampling locations found cPAHs above Aquatic Life Criteria standards for the creek; however, several years of sampling have not shown that contamination from the Joslyn site has increased the general level of contamination in the creek.

If appreciable amounts of site contaminants reached Shingle Creek in the distant past some may still remain bound to sediments or accumulated in living organisms. It is unknown if this occurred to any significant extent in the past, or if people might be exposed in ways that pose health risks due to chemicals. Without any information to determine if contaminants remain in the creek or if people use the creek in ways which might result in exposure to contaminants, it is unknown if there is any health risk associated with this potential route.

3. Biota

Wildlife (ducks, geese, etc.) use the wetland at the northwest border of the site where the non-conforming soils were detected and removed. This area was investigated and contaminated sediments and soils were excavated. Wildlife may also use the ponds and Shingle Creek.

If site contaminants remain undetected in the wetland sediments, ponds, creek bed, or food chain due to past releases from the site, the wildlife may have been or could become contaminated to an unknown extent. PCP is expected to bioaccumulate in aquatic organisms to some degree, although metabolism is also expected. PCP biomagnification in the aquatic food chain has not been evident in the literature (ATSDR 1989c), but in general, consumption of aquatic or semi-aquatic organisms which bioconcentrate the chemical may be an important means of exposure under conditions of significant contamination of aquatic media. Several PAHs and polychlorinated dioxins also have high potential for bioaccumulation (EPA 1979). The importance of potential food chain impacts on humans is likely to be low because any remaining contamination in Shingle Creek and Twin Lakes is not expected to be great, but also cannot be ruled out fully due to a lack of sampling data

C. Pathways Eliminated from Consideration

1. Municipal Water

Results of groundwater monitoring have indicated the presence of low levels of PAHs in the deep sand aquifer and the St. Peter bedrock at the site, and just downgradient of the site. The Prairie du Chien-Jordan bedrock aquifers beneath the St. Peter have not been tested on-site. However, the bedrock aquifers between the site and the Mississippi River are thought to be used only for industrial and residential nonpotable purposes. The St. Peter and Prairie du Chien-Jordan aquifers discharge to the Mississippi River.

The Prairie du Chien-Jordan bedrock aquifers are important sources of drinking water for the Twin Cities metropolitan area. The municipal well nearest to the site draws from the Jordan and is about 1 mile to the northeast of the site. Ground-water flow is east-southeast, so the municipal well should not be affected by site contaminants. Since no municipal wells are in the path of groundwater flow between the site and the Mississippi River, the low-level contamination in the St. Peter bedrock unit between the site and the river is not likely to cause a threat to the metropolitan drinking water supply.

2. Surface Water

  a. Twin Lakes

Surface runoff from the site to Twin Lakes is unlikely because of the relatively flat topography of the site. Runoff is also minimized by internal site drainage caused by berm barriers and absorptive, sandy soil that water can easily infiltrate. Groundwater in both the upper and lower aquifers also flows away from the lakes toward the site.

Low levels of both cPAH and nPAH were detected in 1985 lake water samples--but the source is unknown. The levels of PAHs exceeded the Aquatic Life Criteria Surface Water Quality Guidelines. But because the control sample taken from the north end of the lake contained the highest PAH levels, PCP was not detected, and the flow of groundwater is away from the lake, these findings suggest the site does not have a significant impact on water quality in the lake.

Because site contaminants may have been reached Twin Lakes in the past and biota and sediments of the Lakes and adjacent wetlands have not been sampled, human consumption of potentially contaminated wildlife is considered an indeteminate risk (see Pathways Analyses Section B.3), albeit an unlikely one.

  b. Ryan Lake/Ryan Creek

Ryan Lake is located about one-half mile to the southeast of the site, and Ryan Creek flows northeast from Ryan Lake. Although the lake and creek are located in the path of ground-water flow, they sit above the water table and thus would only recharge, not receive, groundwater. Therefore, a pathway for contamination of Ryan Lake or Ryan Creek is unlikely.

3. Agricultural Produce

No farms are located near the site, so there are no farm crops or livestock of concern.


A. Toxicological Evaluation

The primary contaminants in site groundwater and soil are PAHs and PCP. Metals, dioxins, and furans have also been detected in some on-site soil and a few groundwater samples.

A summary of the information gathered from the scientific literature on the relevant routes of exposure and the toxicity of PAHs and PCP is presented below. The majority of this toxicological information was obtained from studies in which laboratory animals were exposed to the chemicals. It is necessary to use animal data since exposure and toxicity data for humans for many chemicals is extremely limited (if available at all).

The purpose of the following toxicological summaries is to provide information about potential human health effects that may result from exposure to these chemicals. However, it is important to realize that several factors determine whether or not harmful effects will occur and their severity if they occur. These factors include: the dose of the chemical (that is, the amount taken into the body), the length of exposure to the chemical, the route of intake of the chemical (for example, ingestion or inhalation), simultaneous exposure to other chemicals (for example drugs, environmental pollutants, or chemicals in the workplace), and individual characteristics such as age, sex, nutritional status, family traits (genetics), and general state of health.

Unless otherwise referenced, the following toxicological information was obtained from ATSDR Toxicological Profiles for Polycyclic Aromatic Hydrocarbons and Pentachlorophenol.

1. Polycyclic Aromatic Hydrocarbons (PAHs)

PAHs are found throughout the environment. The primary source of many PAHs in air is the incomplete combustion of wood and fossil fuels. PAHs are products of common sources as motor vehicle exhaust, wood burning stoves and furnaces, cigarette smoke, industrial smoke and soot, and charcoal-broiled foods. PAHs found in the wood preservative creosote include chrysene, naphthalene, phenanthrene, fluoranthene, pyrene, acenaphthene, methylnaphthalenes, and anthracene (ATSDR 1990e). Most human exposure is to a mixture of PAHs, as opposed to a single PAH compound.

Smaller PAHs with two rings, such as naphthalene, have a higher vapor pressure and are more water soluble than those with five rings, such as benzo[a]pyrene (B[a]P) (EPA 1979). While there will be some volatilization of the smaller PAHs, those with larger structures are unlikely to volatilize appreciably (Southworth 1979). Dissolved PAHs will breakdown in light rapidly. PAHs are very persistent in sediment and aquatic systems; for example, the half-life for B[a]P in hydrocarbon-contaminated sediments is about 2.4 years, but may be 10-400 times longer in uncontaminated sediments (Herbes and Schwall, 1978). In soil, biodegradation is the major fate, but it is a slow process.

There are essentially no experimental or clinical data that provide evidence for a direct association between human exposure (ingestion, inhalation, or skin contact) to individual PAHs and adverse health effects. Therefore, in order to try to predict adverse responses in humans following exposure to PAHs, toxicologists must rely on reported effects in humans (primarily cancer) after exposure to complex mixtures of PAHs and on information derived from studies in which high doses of PAHs were administered to animals. However, even when animal studies are reviewed, it is evident that there are very little data on the potential non-carcinogenic and carcinogenic effects of many PAHs (ATSDR 1989b, 1990a, 1990b, 1990d, 1990e, 1990f, 1990g). The carcinogenic PAH benzo[a]pyrene (B[a]P) has been the most-studied PAH in animals, and the toxicity of it and other PAHs in humans is often inferred from its toxicity (ATSDR 1990b, 1990g). The following profile on PAHs discusses the carcinogenic and non-carcinogenic effects of PAHs for which data are available.

B[a]P absorption following inhalation (Sun et al. 1982) and ingestion (Hecht et al. 1979) is nearly complete. Studies suggest dermal absorption may be also appreciable (IARC 1973; Kao et al. 1985). With a few exceptions where dermal absorption is slower, data indicate that absorption of other PAHs is quantitatively similar to that of B[a]P. Distribution is quantitatively dependent on the route of exposure (ATSDR 1987a) and on the associated medium (Sun et al. 1982). Orally administered B[a]P, benz[a]anthracene, chrysene, and dibenz[a,h]anthracene primarily distribute to blood, liver, lung, and kidney (ATSDR 1989b, 1990a, 1990d, 1990f).

The non-carcinogenic PAH naphthalene has produced nausea, vomiting, abdominal pain, diarrhea, and even death when ingested in large doses following suicide attempts and accidental ingestion of naphthalene-containing mothballs by children (ATSDR 1990h).

Orally administered B[a]P at 120 mg/kg-day for 180 days produced adverse effects on the bone marrow of mice (ATSDR 1989b). These effects included a decrease in all types of blood cells and aplastic anemia. B[a]P has also been shown to cause allergic reactions when applied to the skin of mice (ATSDR 1989b). Oral administration of certain PAHs has been shown to cause changes in liver function in laboratory animals; such changes are not considered to be serious. Death may occur as a result of the hematopoietic toxicity of B[a]P (Robinson et al. 1975). Exposure to naphthalene can result in cataracts and hemolytic anemia. Results of studies employing dermal exposure are difficult to interpret but may indicate appreciable toxicity via this route.

There are no studies available on either the reproductive or developmental effects (that is, the production of birth defects) of either B[a]P or any other PAH in humans (ATSDR 1989b, 1990g). The results of studies using experimental animals suggest that oral exposure during pregnancy to very large doses of B[a]P is associated with an impairment of reproductive ability and the production of birth defects (ATSDR 1989b). Oral exposure of pregnant animals to B[a]P demonstrates transplacental transfer of the chemical (Shendrikova and Aleksandrov 1974) and has resulted in adverse reproductive outcomes (Rigdon and Rennels 1964; Legraverend et al. 1984) and developmental toxicity in offspring (MacKenzie and Angevine 1981). Other PAHs have also been demonstrated to cause reproductive toxicity (EPA 1982).

B[a]P has been extensively evaluated for genotoxic effects, and the results have been overwhelmingly positive (ATSDR 1989b). These studies show B[a]P and PAH mixtures are capable of producing heritable genetic damage and cancer. Other cPAHs have similarly been shown to produce genotoxic effects. Noncarcinogenic PAHs such as naphthalene do not demonstrate genotoxicity.

The majority of the research on the health effects of PAHs has focused on their ability to cause cancer. Elucidation of the mechanism of B[a]P metabolism and carcinogenicity has allowed the development of a predictive model for carcinogenic potential of other PAHs (Jerina et al. 1980). Those PAHs with two or three rings are less likely to be carcinogenic, although some, such as fluoranthene, are cocarcinogens with B[a]P (EPA 1982). When ingested by mice and rats, the PAHs benzo[a]pyrene benz[a]anthracene, dibenz[a,h]anthracene, and 7H-dibenzo[c,g]carbazole induced liver, lung, forestomach and breast tumors (NTP 1989). B[a]P exposure has resulted in tumors in experimental animals by all studied routes of exposure, including oral, dermal, injection, inhalation, and transplacental (IARC 1973, 1983).

Results of epidemiological studies show increased lung cancer in workers exposed to air emissions containing PAHs and other carcinogenic compounds (Mazumdar et al. 1975; Hammond et al. 1976). Dermal exposure to shale oils and coal tar (which contain PAHs in addition to other carcinogens) has been associated with an increased incidence of skin tumors in workers (IARC 1985). Workers exposed by skin contact to creosote (composed primarily of PAHs) have also developed skin tumors (NTP 1989). When applied to the skin, all fifteen PAHs listed below induced skin tumors in mice.

The National Toxicology Program of the U.S. Department of Health and Human Services has determined that the following fifteen PAHs may reasonably be anticipated to cause cancer in humans (NTP 1989):

Benzo[a]anthracene Benzo[b]fluoranthene Benzo[j]fluoranthene
Benzo[k]fluoranthene Benzo[a]pyrene Dibenz[a,h]acridine
Dibenz[a,j]acridine Dibenz[a,h]anthracene 7H-Dibenzo[c,g]carbazole
Dibenzo[a,e]pyrene Dibenzo[a,h]pyrene Dibenzo[a,i]pyrene
Dibenzo[a,l]pyrene Indeno[1,2,3-cd]pyrene 5-Methylchrysene

This list does not correspond exactly to those PAHs selected as carcinogenic (cPAHs or termed as List 1 PAHs) in data reports for the Joslyn site (Appendix A). Site-related environmental media samples were analyzed for six of the fifteen carcinogenic PAHs shown above. One of those tested for, benzo[k]fluoranthene, was included in the totals of nPAHs (termed List 2 in sampling reports) in reports of investigation and monitoring data. Samples from on- and off-site environmental media have not been analyzed for the remaining nine carcinogenic PAHs.

Recommended Allowable Levels (RALs) (see Environmental Contamination and Other Hazards subsection for a discussion of RALs) have been developed by MDH for five nPAHs (MDH 1991):

nPAHs RAL (µg/L)
Acenapthene 4000
Anthracene 2000
Fluoranthene 300
Fluorene 300
Naphthalene 30

For the other nPAHs, RALs are set to be protective against unknown health effects (there is little or no toxicological data on them). For the nPAHs other than the five listed above, the RAL is 0.3 µg/L. This RAL is compared to their total concentration in the drinking water sample. For all cPAHs (see list above), the RAL is 0.03 µg/L. Again, this RAL is compared to the total concentration of cPAHs in the water sample. For example, if each of the fifteen cPAHs were found in a private drinking water well at 0.0025 µg/L (or greater), the RAL would be exceeded (total cPAHs of 0.0375 µg/L vs. the RAL of 0.03 µg/L) and appropriate actions would be taken by MDH.

The Threshold Limit Value (TLV) for occupational exposure to coal dust is 2 mg/m3; the TLV for occupational exposure to coal tar pitch volatiles is 0.2 mg/m3 (ACGIH 1990). If ambient air is sampled broadly for PAHs or specifically for cPAHs in air at the Joslyn site during excavation and remediation of contaminated soils can be compared to these values for initial screening of monitoring results. However, occupational standards may not be adequately protective of the general population.

The MPCA Aquatic Life Criteria for the protection of human health for ambient water levels of PAHs are a maximum sum of 0.07 µg/L for cPAHs and a maximum sum of 17.0 µg/L for nPAHs at the time the Record of Decision (ROD) was completed for the Joslyn site. These criteria apply to surface waters used for fishing but not as a drinking water source. Since the writing of the ROD, the criteria number for nPAHs was replaced by compound specific levels for acenaphthene (12 µg/L), anthracene (0.029 µg/L), fluoranthene (1.1 µg/L), phenanthrene (2.1 µg/L), and naphthalene (81 µg/L proposed). Currently, no comparison values are available for PAHs in soil or sediments.

2. Pentachlorophenol

Pentachlorophenol (PCP) is readily absorbed into the body following ingestion, inhalation, and skin contact (EPA 1985a). Virtually all of an administered dose is quickly absorbed from drinking water (Braun et al. 1978; Meerman et al. 1983). PCP is bound to protein in the plasma and accumulates in the liver, kidney, brain, spleen, and fat (Braun et al. 1977). PCP is not readily metabolized and is excreted in the urine primarily as unchanged PCP (Braun et al. 1978). Chlorophenols exert their acutely toxic effect by uncoupling oxidative phosphorylation from the electron transport system. In humans this has resulted in profuse sweating, fever, weight loss, and gastrointestinal complaints. Heart failure can also occur. Long-term inhalation of PCP in the workplace has been reported to result in abdominal pain, nausea, vomiting, eye and nose irritation, and decreased kidney function.

Human exposure to low levels of PCP results in local irritation. Dusts can be particularly irritating to eyes and nose at concentrations greater than 1 mg/m3. Severe or prolonged exposure may result in contact dermatitis and chloracne. Long-term inhalation of PCP vapor at concentrations ranging from 0.3 to 180 µg/m3 did not produce any neurological effects in humans. There is no clear epidemiological evidence to indicate that inhalation of PCP vapor produces cancer in humans.

No toxicological data are available describing the effects in humans following long-term ingestion of PCP. However, numerous organs and tissues in experimental animals such as the liver, kidney, central nervous system (brain), heart, blood and the immune system have been adversely affected following ingestion of large doses of PCP. Highly purified PCP has not been shown to adversely effect the ability of experimental animals to reproduce or to produce birth defects in animals whose mothers ingested PCP during pregnancy. There is no convincing evidence that ingestion of PCP causes cancer in humans; PCP has, however, been shown to be carcinogenic in mice following long-term ingestion. Based on these animal studies, the U.S. EPA designates PCP as a Group B2 carcinogen (probable human carcinogen) by the ingestion route.

Most of the information on adverse effects produced following skin contact with PCP come from case reports of persons either exposed in the workplace or in the home following the misuse of PCP-containing solutions. Organs most often affected in these situations include the liver, kidney, blood, lungs, and the central nervous system. Skin contact with PCP can cause severe skin irritation with swelling and pain.

The toxicity of PCP can be difficult to characterize because often the PCP formula used in wood treatment is contaminated with low levels of other chemicals known to be toxic. Technical-grade PCP contains from 85 to 99% PCP with different chlorophenol impurities (tetrachlorophenol, trichloro- phenol, chlorinated phenoxyphenols, and trace amounts of dibenzo-p-dioxins and dibenzofurans).

Liver and kidney effects (increased weights and pigmentation) at low doses (3 mg/kg/day) were seen in animals exposed to a technical grade of PCP that contained high levels of dioxins, but effects were not seen in animals exposed to an improved technical grade (Johnson et al. 1973; Schwetz et al. 1978). Technical-grade PCP produced altered immune response in mice, but pure PCP did not (Kerkvliet et al. 1982). PCP has been shown to be embryotoxic and teratogenic in animal studies (Schwetz et al. 1974; Schwetz et al. 1978).

Results of studies on the mutagenicity of PCP are conflicting, but most of them (both human and nonhuman animal studies) have produced negative results. There is no convincing evidence that ingestion of PCP causes cancer in humans; PCP has, however, been shown to cause cancer in mice following long-term ingestion (ATSDR 1989c). Based upon these animal studies, the U.S. EPA designates PCP as a Group B2 carcinogen (it is a probable human carcinogen by the ingestion route) (IRIS 1993). Because studies regarding the toxicity of PCP in humans after long-term inhalation have not been performed, the effects in humans of lengthy exposure to PCP in air are not known. There is no convincing evidence that indicates inhalation of PCP vapor produces cancer in humans (ATSDR 1989c).

Based on a study that indicated that 3 mg/kg/day is a No Adverse Effect Level for reproductive effects, the EPA Office of Drinking Water has estimated a Lifetime Health Advisory of 220 µg/L for drinking water (reference dose 0.03 mg/kg/day; EPA 1987). The RAL set by MDH for the non-carcinogenic effects of PCP is 200 µg/L (MDH 1991) and a RAL based upon protecting against carcinogenic effects is proposed for 3.0 µg/L. The maximum concentration of PCP detected in the groundwater of the surficial aquifer has been 25,000 µg/L.

3. Site-Specific Implications

In the past people may have been exposed to site contaminants through activities at the site or through contact with contaminated off-site media such as groundwater used for drinking and household purposes. MDH is not able to predict if adverse health effects will occur in humans who may have been exposed in the past, because there is no reliable or representative information available regarding levels of contaminants to which people may have been exposed by any route. The duration of likely and potential past exposures is also unknown.

The highest level of PCP detected in off-site groundwater was 950 µg/L: This level is above health-based guidelines for drinking water exposure. It is possible that a person who regularly consumed and or had skin contact with water contaminated at this level may have experienced acute adverse health effects such as irritation. Other health effects may be possible but cannot be predicted without more information than is available. The odor threshold for PCP in water (level at which it can first be smelled) is around 850 µg/L (ATSDR 1989c), so if any wells had higher concentrations than that, users probably would have smelled a slight chemical odor.

The highest level of total PAHs detected in off-site groundwater was 250 µg/L and it is possible regular users could experience adverse health effects if their well was as contaminated and they used contaminated water for a prolonged period. Long term exposure to even much lower levels of carcinogenic PAHs, such as those recently found in off-site monitoring wells south of the site, could result in cancer or other health effects.

The maximum concentration of cPAH detected in the surficial aquifer at the Joslyn site has been 6,200 µg/L; however, these on-site wells are not used for drinking. The maximum cPAH concentration detected in the lower aquifer was 0.031 µg/L in 1985; this level has not been detected in the lower aquifer since, but recent samples from on site deep wells have yielded increasing levels of cPAHs up to 0.026 µg/L. In recent years, the levels of PAHs in off-site monitoring wells 125 and 126 have increased to exceed Minnesota health-based drinking water guidelines (RALs). MDH considers this groundwater to be unacceptable for human consumption. A risk assessment for continued nonpotable use of private wells near the site was conducted in 1990 by Barr Engineering and an addendum was prepared in 1991. The assessment concluded that the health risk from continued non-potable use of the wells was not significant (Barr 1990b, 1991).

MDH reviewed the two risk assessment reports and agrees that the levels of chemicals estimated to be present in the vicinity of the private wells near the site pose no immediate health concern to persons using the wells on a seasonal basis for nonpotable purposes which result in no direct contact with chemicals potentially in the water. However, because contaminant levels and water usage were only inferred or estimated and nearby residents may use groundwater from private wells more extensively than assumed in the risk assessment, MDH feels that potential health risks cannot be ruled out if contaminated wells are used in ways that result in exposure to even low levels of contaminants such as the carcinogenic PAHs and the dioxins and furans. Given that the small (but also uncertain) risk associated with continued use of this contaminated groundwater is avoidable by selective usage, it may be considered to be unacceptable to some current or future users. Thus, MDH believes users should be informed about the situation and allowed to decide what level of risk they chose to accept.

There is no data on contaminants in the residential wells themselves and very little information about off-site groundwater quality at the specific locations of private wells which may be used. The carcinogenic risks were not assessed in an entirely conservative manner because: 1) several carcinogenic PAHs have not been analyzed for; 2) carcinogenic PAHs were not considered in the risk assessment even though their levels exceeded Minnesota health-based recommended limits for private drinking water wells (RALs) in at least one off-site monitoring well (W126) as recently as 1991; 3) the excess cancer risk due to low levels of dioxins and furans should have been combined with that due to potential exposure to cPAHs; 4) unmeasured past exposure to carcinogenic agents in the wells was not considered, although it contributes to the lifetime risk of long-term residents who may still use their wells. In addition, if the groundwater is used more extensively than was assumed for the non-potable use scenarios evaluated then the risk may be underestimated.

The recently measured chlorinated dioxins and furans in groundwater expressed as toxicity equivalents of 2,3,7,8-TCDD (TCDD-EQ) ranged from 0.0000003 to 0.0000039 µg/L; which are below the health based-comparison values shown in Table 8 (Appendix B). Therefore, the health risk associated with these levels of dioxins and furans appears to be insignificant, based upon the toxic equivalency method of estimating risk from exposure to mixtures of these related compounds. This conclusion, however, is based upon results from only five samples taken at a single time. If these measured concentrations do not accurately represent the concentrations in private wells or if the levels of dioxins and/or furans were to increase and humans were known to use this groundwater, there may be a health concern due to these chemicals as well as to the carcinogenic PAHs.

In the past, if humans had direct contact with the highly contaminated soil on the site, they may have experienced immediate or short-term health effects such as those described for PCP. If past exposure to soil or contaminated dust was frequent and prolonged, long-term chronic or latent effects could still occur due to past exposures. MDH is not aware of any reports of health effects experienced by current or former residents of the area.

Air monitoring at the site does not suggest that dust generation and volatilization are significant on or off-site, if the results reported are generalizable and representative. The dust levels (total dust) measured on-site are not entirely comparable to standards for the respirable particulate fraction (PM10). Although dust levels measured on site suggested that national air standards for PM10 were not exceeded off-site, these standards may not be adequately protective for some sensitive individuals, such as those with asthma or other respiratory conditions. This may be true, especially if irritant chemicals are attached to the dust particles. Therefore the risk from airborne contaminants and dusts is likely to be low, but might be significant for some individuals if they are actually exposed -- a factor which is not known.

Recent groundwater monitoring results, and past site visit observations (odors, breached security fence), and an understanding of site-specific pathways (for example, continued nonpotable use of downgradient private wells) suggest that some individuals could currently be exposed to very low levels of site-related contaminants. However, available information do not suggest that under current conditions of contamination and groundwater use people are exposed to site contaminants frequently enough or to levels sufficient to cause significant health effects. For groundwater however, this is based upon inferred groundwater quality at the point of use, and estimated or past reported use. Thus, the available data on contaminant concentrations and potential exposures are not sufficient to rule out the potential for adverse health effects, although unlikely, due to past, current, and future exposures to low or unknown levels of contaminants.

At the present time, the greatest potential for a health risk to a person other than a site worker involves a trespasser who could be exposed directly to contaminated media on site.

B. Health Outcome Data Evaluation

From the available incidence data described in the Community Health Concerns Section, it would not be possible to conclude that the site has, or has not, affected the health of nearby populations. Thus, a review of available health-outcome data is not warranted at this time.

C. Community Health Concerns Evaluation

Although no specific health-related concerns are known at this time, members of the public living near the site have not shown much interest in the site and may not be very aware of the contamination at the site. The only interest known at this time relates to odors detectable off-site. These odors have been confirmed by MDH and MPCA staff during a site visit, however, there are no representative air sampling data available for assessing this issue.


Based on information reviewed, MDH and ATSDR have concluded that under current conditions the Joslyn site poses an indeterminate health risk. The indeterminate risk classification is selected indicating "that available data do not indicate that people are being or have been exposed to levels of site contaminants that would be expected to cause adverse health effects, but data or information are not available for all environmental media to which people could be exposed." If humans are or were exposed to hazardous substances in contaminated groundwater, volatilized from waste water, and those in on-site surface soil, they may be at risk of adverse health effects. This potential risk is considered to be low, because such exposures are not likely to be frequent or extensive due to precautions taken by the site owner to minimize or prevent such exposures from ocurring. The greatest potential health risks involve any trespassers onto the site or any on-site workers who do not follow prescribed safety precautions.

Access to contaminated media on-site is currently well restricted and Joslyn has significantly increased efforts to control the property. In the past, trespassers had vandalized the fence and thereby compromised the safety measures. In response Joslyn has recently (Spring 1993) authorized additional fencing, additional warning signs, regular inspection and repair of fences, increased security patrols from both a private security guard and from the local police force (personal communication with Mr. Carl Grabinski of Joslyn). These increased efforts should discourage trespassing and alert the public of contaminants within the fenced area.

The extent of groundwater and soil contamination has been generally characterized; well enough for design and implementation of several remediation activities. The existing monitoring well network is extensive on-site and extends mainly in the direction of groundwater flow from the site (to the south and east). However, it is unknown how far to the south or southeast site contaminants could have migrated in the past, if this ocurred. Sampling following a 1979 fire east of the site did not show PAHs or PCP in three shallow wells, giving recent data on the probable eastward limit on site contamination of the upper aquifer. It is also unknown how deep contaminants may have migrated or what their current levels are in the deeper groundwater units off-site because only three wells monitor the lower aquifer on-site and another two off-site. Despite repeated detections of PCP (1987-1989) and nPAHs (1986-1991) in samples from off-site middle sand well W223, the corresponding deep well W323 (the only deep well in the direction of the greatest measured off-site concentrations) was not sampled since 1988.

It has not been determined if arsenic and/or chromium are present in residential wells at levels of concern because the groundwater monitoring data collected from filtered samples of monitoring wells may underestimate the levels that could occur in private wells. These compounds, if they are present in groundwater used by private wells of the area, are not a health concern unless people use their wells for regular consumption.

There is no current use of groundwater on-site and no potable use known in the areas of detected off-site groundwater contamination. However, if in the past high levels of groundwater contaminants moved beyond the area of groundwater monitoring, people who used or may be using groundwater in the direction of any such flow may have been or might currently be exposed to site contaminants at unknown concentrations.

The risk from continued non-potable use of contaminated groundwater near the site is likely to be very low, but available data are not adequate to rule out the potential for unquantified current and future risks. Due to this uncertainty, MDH feels well owners should be educated about potential risks associated with continued use of the private wells near the site or in the direction of the plume that was detected off-site. At the very least, users of groundwater in the vicinity of the site should be informed about a few simple precautions they can use which could limit the potential for exposure.

Contaminated groundwater below the site is being remediated through a shallow pump-out system. The capture zone for the shallow groundwater is believed to approximate the shape of the southeastern site boundary and extend into the residential area to the south. Extraction of the DNAPL under the middle of the site is also planned to begin soon. Product removed from the DNAPL wells will be shipped to an off-site facility for disposal.

Investigation is planned to locate the terminus of the pipeline traced to the site's northern edge. The possibility of any off-site contamination due to the pipeline will be evaluated when the investigation is conducted.

It is unknown if contaminants from the site may have reached Shingle Creek in the past (prior to monitoring efforts) at significant levels. As recently as 1990, elevated levels of PCP and nPAHs in the drain tile waters showed site contamination of the system; however, since 1991, sampling did not show an appreciable contribution of site contaminants to the existing contamination in the creek which is unrelated to the Joslyn site. It is unknown if there is any exposures to creek waters or sediments that could pose a health concern if contaminants are present. The importance of this data gap is judged to be low unless both: a) there are, or have been, large amounts of contaminants reaching the creek; and b) there is reason to think that people are exposed extensively to creek sediments or water in the vicinity of the drain tile outfall. The likelihood of site contaminants reaching the drain tile in the future is lessened by the on-site groundwater pump-out system.

Although it may be unlikely, it is unknown if any site contaminants reached Twin Lakes in the past. MDH is unaware of sediment or biota testing that can show that sediments in the nearby wetland fringe or lake area do not contain bound contaminants (e.g. PAHs or PCP). Water sampling during the RI did not detect elevated levels of PCP or PAHs that could be linked to the site in the water column and thus it appears unlikely that high levels of contaminants are present in the Twin Lakes system. However, this represents a data gap considered to be of minor importance unless a large amount of undiscovered contaminants could be involved: There is no information which suggests this is the case.

The soil treatment is expected to reduce contaminant concentrations in treated soil to goals of 100 mg/kg cPAH compounds and 150 mg/kg PCP, but will not reduce dioxin, furan, or metals content of soils. After treatment, soils will remain on-site, covered with three feet of clean soil material and vegetated. As long as the cap of clean soil remains undisturbed, direct contact with contaminants remaining in the soil will not be possible.

The possibility of human exposure to contaminated fugitive dusts is minimized by frequently wetting the soil, and by the plastic cover over the soil stockpile. Dust from site traffic is also minimized by application of binders and water sprinkling during dry periods. Remediation workers are required to follow health and safety plans for site activities which are intended to be protective. Estimates of theoretical health risks to the population surrounding the site from air-borne exposure dioxins and furans were negligibly low as calculated by Barr in a Risk Evaluation report (Appendix C of Barr 1993). Potential risks to on-site workers were great enough to reinforce the need for adherence to personal protection requirements outlined in the site safety plan.

Contaminants that can volatilize may be released into the air from free product, highly contaminated soil (before and during treatment), or extracted groundwater. Inhalation of volatile contaminants is possible, especially on-site in the immediate proximity of the contaminated materials. Again, site workers are expected to adhere to the requirements of the safety plan appropriate to their activities. People working or living in the site's immediate vicinity may also be exposed to very low levels of volatilized compounds, which might be experienced as occasional odors.


  1. The groundwater remediation operations must be continued until clean-up goals for groundwater have been achieved and approved by MPCA. Institutional controls on groundwater use should be initiated near the site to prevent potential future use of contaminated downgradient aquifers. The area of groundwater contamination should be referred to the MDH Well Drilling Advisory Program for consideration of any additional appropriate control measures.
  2. Regular monitoring of off-site groundwater quality should be continued. Careful attention should be given to contaminant concentrations in monitoring wells south and east of the site. If monitoring results indicate that contaminants are migrating further from the site, the monitoring well network and the well-search area may need to be expanded.

  3. Contaminants in groundwater which are already off-site (to the south and east) will not be removed by the groundwater remedy. Therefore, any continued or new use of the groundwater near the Joslyn site (in areas which could reasonably be impacted by the offsite plume remnant) should be monitored, restricted, or users informed as appropriate based upon the levels of any contaminants and confidence in future groundwater quality.
  4. MDH recommends that any regular users of private wells in the vicinity of the Joslyn site avoid using private well water in ways that result in frequent or extensive skin or eye contact with water and swallowing (for example bathing, playing in a swimming pool, washing of body or face) or intentional drinking. Periodic usage is unlikely to pose any significant risk, but regular direct contact with well water might pose a low, (yet unquantified) risk that is easily avoidable if well users are informed and selective in their usage. MDH will prepare a general notification to be given to area well owners explaining this precautionary advice.

    If area residents choose to use a private well, which may be or could become contaminated, in ways that result in regular exposure to any contaminants which may be present, MDH recommends that the residents test their water. Analyses for metals, dioxins, and furans should be included. Unfiltered samples should be used for metal analyses.

  5. If on-site soil is used to cap treated soil, it should be tested for PAHs, PCP, dioxins, furans, and heavy metals to ensure that it does not contain contaminants at levels that would pose a potential risk to human health. Soil from off-site sources should continue to be evaluated.
  6. When soil remediation is complete, measures should be taken to ensure that the clean soil cover is not disturbed. Any future development of the site should be planned so as not to expose treated soils at the surface.

  7. The Highway 100 drain-tile/storm sewer system should continue to be sampled for PAHs and PCP when the water table is elevated and water is flowing in the drain tile system. If contaminants that can be linked with the site are found in the system above appropriate MPCA criteria values for surface water, the outfall water and the creek should also be sampled. The contribution of contaminants in drain-tile water should be compared to background levels in the creek.

  8. MDH recommends sampling of sediments of Twin Lakes near the site to assess if any contaminants have concentrated in the sediments of the lake and wetlands adjacent to the site. Similarly, sediments of Shingle Creek should be tested for PCP that may have accumulated from past discharges.

  9. The contaminated subsurface soil remaining north of the drain line location should be removed or institutional controls placed upon land use. The terminus of the pipeline should also be located. If the pipeline runs off site, surrounding soils and those at its outfall should be sampled and analyzed for site contaminants (dioxins, furans, metals, chlorophenols, and PAHs). The potential for LNAPL and DNAPL should also be investigated in any such areas.

  10. The public is advised to respect the signs and fences at the Joslyn property. Access to the site should continue to be controlled to prevent unauthorized entry. The site fence should be inspected regularly and repaired if needed. MDH also recommends additional signs to discourage trespassing and warn outsiders of the potential hazards within and the fact that the site is private property.

  11. Measures to control airborne dusts, such as frequently wetting the soil and keeping the soil stockpile covered with plastic must be continued. Monitoring should be continued at the site's border to demonstrate continued effectiveness of dust control efforts.

  12. Air monitoring at the site's border, between the nearest residences and the contaminated soils in the LTU or the stockpiled soil, should be continued during periods of site work using appropriate sampling and analytic methods. Air samples should be tested for volatile PAHs and phenols, including PCP. Volatile contaminants should be identified and their maximum levels in the air quantified through representative sampling.

  13. Ongoing evaluation of worker safety and the need for personnel protection should be continued. All site work must be in accordance with 29 CFR 1910.120, and follow appropriate National Institute for Occupational Safety and Health and Occupational Safety and Health Administration guidelines.
  14. Workers involved in moving the stockpiled soils to the LTU or any other handling of contaminated soil should wear appropriate respiratory protection and clothing as required by the site safety plans. Breathing zone air of workers not wearing respirators should continue to be assessed to ensure compliance with occupational standards for dust and specific site contaminants.

    The control building should be adequately ventilated to prevent inhalation of contaminants volatilized from pump-out water above OSHA standards. The air in the control building should also continue to be monitored on a regular basis for airborne contaminants. The strong odors noted in the building should be characterized and quantified.

  15. Remediation and long-term care and monitoring plans approved by MPCA must be followed.

  16. In accordance with the Comprehensive Environmental Response Compensation, and Liability Act of 1980, as amended, The data and information developed in the Joslyn Manufacturing and Supply Company public health assessment have been evaluated by the Health Activities Recommendation Panel (HARP) for follow-up health activities. In the past, data suggest that people were exposed to site-related contaminants through the use of private wells for drinking water and other household purposes. Due to a lack of data, however, the duration and magnitude of this exposure is unknown. Therefore, HARP has determined that this site be referred for consideration of a dose reconstruction endeavor. In addition, a community health education effort is needed. This effort should be directed at private well users in particular, as well as others such as on-site workers and trespassers. When additional data become available, ATSDR and the Minnesota Department of Health will reevaluate this site for any additional follow-up activities.


The Minnesota Department of Health (MDH) and the Agency for Toxic Substances and Disease Registry (ATSDR) will monitor the progress of all the recommendations outlined above. More specifically, the following are part of the public health action plan for the Joslyn Manufacturing site:

Health Assessors will share groundwater sampling results with the MDH Well Drilling Advisory Program and will request consideration of any appropriate institutional controls on future well installation into groundwater which is or might be contaminated.

MDH will inform users of potentially contaminated groundwater near the site (private wells) about possible health risks and recommended usage.

MDH will assess the air pathway for off-site exposure to volatilized contaminants when additional sampling data become available.

When requested by MPCA, MDH will review sampling data and plans for any further site investigation or site closure actions.

As clean up of the site progresses, the MPCA, U.S. EPA, and /or the MDH will keep the local communities informed through facts sheets, mailings, news releases, or public meetings. Specifically, the MDH will prepare a fact sheet for citizens concerned about the Joslyn site. These fact sheets will be mailed with copies of this health assessment sent for public comment.

If necessary, due to changes in site conditions or land use, MDH will update the health assessment as appropriate.


David B. Jones, M.S.
Research Scientist
Minnesota Department of Health
Division of Environmental Health

ATSDR Regional Representative

Louise Fabinski
Regional Services
Office of the Assistant Administrator, ATSDR

ATSDR Technical Project Officer

Richard R. Kauffman, M.S.
State Programs Section
Remedial Programs Branch
Division of Health Assessment and Consultation, ATSDR


This Joslyn Manufacturing and Supply Company public health assessment was prepared by the Minnesota Department of Health 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 assessment was begun.

Technical Project Officer, SPS, RPB, DHAC

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

Director, DHAC, ATSDR


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Personal Communication with Carl Grabinski of Joslyn Corporation. 5/27/93.

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