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PUBLIC HEALTH ASSESSMENT

MOHAWK TANNERY SITE
NASHUA, HILLSBOROUGH COUNTY, NEW HAMPSHIRE


SUMMARY

The former Mohawk Tannery facility (a.k.a., Granite State Leathers) is located on a 30-acre parcel at 11 Warsaw Avenue in Nashua, New Hampshire. The facility produced tanned hides for leather between 1924 and 1984 and is currently inactive. The property is bordered by the Nashua River to the west and southwest, by residences to the southeast and east, and by a small landfill (the Fimbell Door Landfill) to the north.

On May 11, 2000, the U.S. Environmental Protection Agency (EPA) proposed the Mohawk Tannery Site for the National Priorities List (NPL). Under 42 U.S.C. 9604, the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) must perform a Public Health Assessment for all sites proposed for the NPL within one year. The New Hampshire Department of Health and Human Services (DHHS) completed this Public Health Assessment under its cooperative agreement with ATSDR.

What kind of chemical contamination has been found on the site?

At the Mohawk Tannery facility, animal hides were treated with chemicals to create leather products from 1924 to 1984. Wastewater from the tanning process contained several toxic substances. The contaminated wastewater was stored in two lagoons on the western side of the site before it was discharged to the Nashua River. The sludge that accumulated in these lagoons was occasionally dredged and buried in five disposal areas on the site.

The main contaminants at the site are chromium, phenols/cresols, and dioxin. Chromium and phenols/cresols were used in the tanning process, as tanning agents and fungicides, respectively. Dioxin was not used in the tanning process but is a common impurity in chlorinated phenols. None of these chemicals is very soluble in water. Therefore, the contamination onsite is relatively immobile (i.e., does not tend to leach out of soil into groundwater). However, dioxin and, to a lesser extent, phenols/cresols do not degrade over time and, because of their chemical properties, can accumulate in the tissues of humans, animals, and fish.

How might I be exposed to chemical contamination on the site?

There are four known ways that people can currently be exposed to chemicals from the site:

  • Walking or playing inside the fenced portion of the site.
  • Swimming or wading in the Nashua River near the site.
  • Eating fish caught from the Nashua River near the site.
  • Breathing odor-causing compounds in the air near the site.

What health effects might result from exposure to chemical contamination at the site?

None of the current exposures at the site is expected to cause adverse health effects. Therefore, DHHS has categorized current conditions at the site as No Apparent Public Health Hazard according to ATSDR's hazard classification system. However, site remediation is needed because, in the future, changes in the land use or a large flood of the Nashua River could increase exposures to levels that could potentially cause adverse health effects.

  • People who trespass on the site could be exposed to low concentrations of dioxin and other contaminants in the open lagoon; however, these exposures are not expected to affect their health.
  • People who swim or wade in the section of the Nashua River near the site would be exposed to elevated concentrations of chromium and other contaminants, but these exposures would not cause adverse health effects.
  • People who eat fish from the Nashua River near the site would be exposed to low concentrations of dioxins in the fish tissue. As long as fish from this area are not a large portion of a person's diet, these exposures will not cause adverse health effects.
  • Odors near the site are likely caused by hydrogen sulfide, methyl mercaptan, and ammonia in the air. Exposures to these compounds, while a nuisance, are unlikely to result in long-term, serious, adverse health effects. However, sensitive individuals (e.g., asthmatics) may have experienced acute symptoms, such as nausea, headaches, cough, wheezing, and eye-nose-throat irritation, from past exposures when the odors were very strong.

Could current or past exposures to chemical contamination at the site have caused an increased rate of cancer in the community?

No. Current or past exposures to cancer-causing chemicals on the site (e.g., dioxin) are not expected to result in an increased cancer risk. Moreover, DHHS obtained data from the New Hampshire State Cancer Registry and performed a risk ratio analysis on all cancer types combined for the community near the site. This analysis did not find a statistically significant difference in cancer rates between the community and the rest of Nashua.

Is the site being cleaned up?

Yes. From October 2000 to January 2001, EPA performed a Time-Critical Removal Action at the site which removed 55 drums of hazardous materials, asbestos-containing material from the former facility building, corrosive acid from a storage tank, and hazardous materials from the former clarifier facility. EPA also fixed portions of the fence around the site and boarded up the former clarifier building. EPA is working with the New Hampshire Department of Environmental Services (DES) on a cleanup strategy for the rest of the contamination at the site.

Where can I get more information?

The text and appendices of the Public Health Assessment contain more information about the health issues discussed in this summary. To ask questions about this Public Health Assessment or to obtain extra copies of this document, please contact Dennis Pinski in the DHHS Bureau of Health Risk Assessment at (603) 271-4664 or (800) 852-3345 ext. 4664 (toll-free in N.H.). You can also send an email to the Bureau at healthrisk@dhhs.state.nh.us or visit its website at http://www.dhhs.state.nh.us/bhra where the report is available online. Additional copies of this Public Health Assessment will be available at the Reference Desk at the Nashua Public Library at 2 Court Street, Nashua NH 03060 (603-594-3412).

Public comment period for the Draft Public Health Assessment was held April 15, 2001 through May 15, 2001. No written comments were received by DHHS during this period of time.

If you would like more information on the site cleanup efforts, please contact Neil Handler of the EPA at (617) 918-1334 or John Splendore of the DES at (603) 271-5569.


I. PURPOSE

On May 11, 2000, the U.S. Environmental Protection Agency (EPA) proposed the Mohawk Tannery Site for the National Priorities List (NPL).

Under 42 U.S.C. 9604, the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) must perform a Public Health Assessment for all sites proposed for the NPL within one year. A Public Health Assessment is a triage tool used to determine if any actions are needed to protect the community surrounding the hazardous waste site, and to determine if follow-up health activities (e.g., health studies, medical surveillance) should be done. To achieve this goal, this assessment contains three types of evaluations: (1) the identification of pathways of exposure to site contaminants and an evaluation of their public health implications; (2) a summary of relevant and available health outcome data (i.e., cancer registry data); and (3) an evaluation of specific community health concerns about the site.

The New Hampshire Department of Health and Human Services (DHHS) completed this Public Health Assessment under its cooperative agreement with ATSDR.


II. BACKGROUND

(A) Site Description and History

The former Mohawk Tannery facility (a.k.a., Granite State Leathers) is located on a 30-acre parcel at 11 Warsaw Avenue in Nashua, New Hampshire. The facility produced tanned hides for leather between 1924 and 1984 and is currently inactive [15]. The property is bordered by the Nashua River to the west and southwest, by residences to the southeast and east, and by a small landfill (the Fimbell Door Landfill) to the north. The site property consists of two parcels of equal size. The northern parcel contains the former tannery facility and waste disposal areas. The southern parcel is undeveloped. There are no records of waste disposal or leather treatment on the southern property [1].

Leather tanning at the Mohawk Tannery facility produced wastewater containing chromium and other contaminants that was eventually discharged to the Nashua River. Between 1924 and the 1960's, it is not known how or if contaminants were removed from the wastewater before the wastewater was pumped to the river. By the 1960s, the alkaline and acidic waste streams were mixed in two on-site surface impoundments (also called lagoons) to allow for some neutralization and sedimentation before discharge. During the 1970s and early 1980s, more advanced treatment facilities were constructed. For example, in 1981, a secondary clarifier unit was built north of the lagoons to further treat the wastewater before discharge [1].

The lagoons, which have been designated Areas I and II, were periodically dredged to remove the sludge that accumulated in these basins. The sludge and other waste products were buried in five areas on the northern part of the site (known as Areas III, IV, V, VI, and VII) [1]. All of these five disposal areas are currently covered with sand [8]. The southern lagoon, Area II, was taken off line in 1971, and was covered with a layer of logs and 1-2 feet of sand [1]. The northern impoundment, Area I, is still an open lagoon with standing water most of the year. The sludge in Area I was observed to be 6 to 9 feet thick. In Area II, the sludge extends as far as 12-14 feet below the surface. In both areas, the sludge appeared to be a wet, gray or black, clay-like material mixed with hair, humus, and sand [12].

The northern part of the site, which contains the former tanning facility and waste disposal areas, is surrounded by a fence to the north, east, and south and the Nashua River to the west. However, there have been gaps and breaks in the fence. The gate at the end of Fairmount Street is often left open or unlocked. Environmental regulatory staff have observed children riding bikes on the site property in the past.

There are no barriers to access (e.g., fences) around the undeveloped southern part of the property.

There are several businesses that occupy space in the former tannery building. For example, in August 1999, an auto-repair business was observed operating on-site in violation of local zoning ordinances [15]. These businesses operate out of the former tannery building which is on the eastern side of the property on top of a hill. This building is not near the contaminated lagoons (Areas I and II) or disposal areas, which are at lower elevations on the western side of the site.

From October 2000 to January 2001, EPA performed a Time-Critical Removal Action at the site which removed 55 drums of hazardous materials, asbestos-containing material from the former facility building, corrosive acid from a storage tank, and hazardous materials from the former clarifier facility. EPA also fixed portions of the fence around the site and boarded up the former clarifier building.

EPA is working with the New Hampshire Department of Environmental Services (DES) on a cleanup strategy for the site.

(B) DHHS Involvement

After the site was proposed for listing on the NPL, DHHS began work on a Public Health Assessment. To that end, DHHS staff have performed site visits, conducted outreach activities with the nearby community, and completed a Health Consultation. Highlights of DHHS involvement to date are provided below.

  • February 8, 2001 - DHHS distributed an educational needs assessment survey to the residents in the neighborhood near the site. The objective of the survey was to gather community health concerns and questions regarding the site so that these could be addressed in the public health assessment.

  • February 21, 2001 - DHHS staff visited the site to observe current conditions.

  • February 21, 2001 - DHHS held a public availability session at the Amherst Street Elementary School in Nashua. Residents of the community were provided the opportunity to meet with DHHS staff, in a confidential setting, to discuss their health concerns and questions regarding the Mohawk Tannery site. The public availability session was held at the end of a public meeting hosted by EPA and DES.

  • March 12, 2001 - DHHS completed a Health Consultation for EPA on sludge characterization data collected in 2000.

(C) Demographics

Nashua is the second largest city in New Hampshire. According to the U.S. Census, the population of Nashua in 1990 was 79,662 persons. Children less than 5 years old and adults over 65 years old accounted for 18% of the population. The age distribution for the population is summarized in the following table.

Age (years) Persons Percentage
Less than 5 6,425 8%
5 to 17 12,775 16%
18 to 64 52,378 66%
65 to 84 7,279 9%
85 and greater 805 1%
Total 79,662 100%

The total number of people living within one mile of the Mohawk Tannery Site in 1990 was 1,470, which is less than 2% of the town population.

Almost three-quarters of Nashua residents have lived in their current homes for less than 10 years. The average number of years of residence is summarized below.

Years Living in Home Percent of Population
1 year 23%
3 to 5 years 34%
6 to 10 years 14%
11 to 20 years 16%
21 to 30 years 7%
31+ years 6%

However, the DHHS survey indicated that the average length of residence was longer for the people in the community near the site. Of those who responded to the survey, 62% had lived in their home longer than 10 years.

(D) Quality Assurance/Quality Control (QA/QC)

In preparing this document, DHHS relied on the information provided in the referenced documents. Only data collected using appropriate sampling and laboratory methods were considered in this analysis. Data with demonstrated QA/QC problems were excluded from summary tables or exposure calculations unless they provided unique and relevant information. DHHS has confidence in the data for the site because the tests were performed by certified laboratories. Measurements of exposure point concentrations were taken directly from laboratory data sheets to avoid transcription errors.

The health outcome data used in this evaluation were also checked for quality control purposes, and measures were taken to ensure that these data were appropriate.


III. ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

An integral element of every public health assessment is a review of environmental contamination on the site. In the following section, the results from environmental testing at the Mohawk Tannery Site are summarized for each different media (e.g., waste, groundwater, soils, etc.).

Concentrations of chemicals in each of the media have been compared to media-specific health-based comparison values to decide whether any of the compounds need further evaluation. Health-based comparison values are derived using information on the toxicity of the chemical and assuming frequent opportunities for exposure to the contaminated media (e.g., a residential setting). For non-cancer toxicity, DHHS typically uses ATSDR's Minimal Risk Levels or EPA's Reference Doses, which are estimates of daily human exposure to a contaminant that is unlikely to cause adverse non-cancer health effects over a lifetime. Cancer risk comparison values are based on EPA's chemical-specific cancer potency factors and an estimated excess lifetime cancer risk of one in one million.

If the concentration of a chemical is less than its comparison value, it is unlikely that exposure would result in adverse health effects, and further evaluation of exposures to that chemical is not warranted. If the concentration of a chemical exceeds a comparison value, adverse health effects from exposure are not necessarily expected, but potential exposures to that chemical at the site should be evaluated. As a result, the following summary of environmental data highlights the chemicals that have been found on the site at concentrations above health-based comparison values. Please see Appendix F for more information on health comparison values.

In the Discussion section later in this document, there will be an evaluation of the public health implications of exposure to contaminants with concentrations greater than health comparison values.

(A) Site Conceptual Model - An Overview of the Mohawk Tannery

A site conceptual model is a general description of the processes and the conditions that have been observed at a particular site. It is meant to provide the reader with an overview of the site so that the detailed information provided in the following sections can be taken in context.

At the Mohawk Tannery facility, animal hides were treated with chemicals to create leather products from 1924 to 1984. Wastewater from the tanning process contained several toxic substances. The contaminated wastewater was stored in two lagoons on the western side of the site before it was discharged to the Nashua River. The sludge that accumulated in these lagoons was occasionally dredged and buried in five disposal areas on the site.

The main contaminants at the site are chromium, phenols/cresols, and dioxin. Chromium and phenols/cresols were used in the tanning process, as tanning agents and fungicides, respectively. Dioxin was not used in the tanning process but is a common impurity in chlorinated phenols. None of these chemicals is very soluble in water. Therefore, the contamination onsite is relatively immobile (i.e., does not tend to leach out of soil into groundwater). However, dioxin and, to a lesser extent, phenols/cresols do not degrade over time and, because of their chemical properties, can accumulate in the tissues of humans, animals, and fish.

(B) Tannery Sludge and Wastes

Contaminated sludges are present in the two lagoons adjacent to the Nashua River where tannery wastewater was stored. Five other areas of the site contain contaminated sludge because sludge from the lagoons was dredged and buried in these areas.

Sludges in the disposal areas and lagoons onsite have been tested several times between 1975 and 2000.

  • 1975: Five sludge samples from Area I were analyzed for chromium [1].
  • 1983: One sample of the sludge being sent to the Fimbell Door Landfill was tested for metals, volatile organic compounds (VOCs), and acid-extractable organic compounds [1].
  • 1985: Seven sludge samples from various locations were tested for VOCs and acid-extractable organic compounds [2].
  • 1986: Eight sludge samples from the Mohawk Tannery site and the Fimbell Door Landfill were analyzed for dioxins and furans [3].
  • 1989: Five samples from Areas I, II, VI, and VII were tested for metals, VOCs, and base-neutral extractable organics [6].
  • 1999: One sample of sludge from the former clarifier facility and five samples of drummed wastes were tested for metals, VOCs, and base-neutral organic compounds [9].
  • 2000: Six samples from Areas I and II were tested for dioxins and furans and hazardous waste characteristics. A composite sample from each area was tested for semi-volatile organic compounds, total chromium and hexavalent chromium [12]
  • 2000: One sample of sludge from the clarifier facility was tested for arsenic, chromium (total and hexavalent), and dioxin [13].

The maximum concentrations of chemicals detected in the sludges from Areas I-VII, sludges from the clarifier facility, and drummed wastes are presented in Tables 1, 2, and 3, respectively. The major compounds of health concern in these sludges are chromium, phenols/cresols, and dioxin. These compounds of concern were identified because either the maximum concentration was greater than a health comparison value or the chemical was a major component of the tanning process.

(1) Chromium

Chromium is the most common heavy metal waste from the tanning process [21]. In the environment, chromium can be in two different forms: trivalent chromium and hexavalent chromium. Determining the form of chromium at a site is important because trivalent chromium is much less toxic than hexavalent chromium.

In the disposal areas and lagoons onsite, the maximum concentration of total chromium (trivalent and hexavalent combined) was 31,000 milligrams per kilogram (mg/kg). There were similarly high concentrations of total chromium in the clarifier waste (31,000 mg/kg) but lower concentrations in the drummed wastes (328 mg/kg).

Although the concentrations of total chromium are higher than background (33 mg/kg) [18], tests indicate that virtually all (99%) of the chromium in the sludge is in the relatively non-toxic trivalent form. This is consistent with the fact that almost all of the chromium used in leather tanning is trivalent [21]. The health comparison value for trivalent chromium in residential soils is 80,000 mg/kg. The highest concentrations of total chromium detected on the site (31,000 mg/kg) are below this level. The highest concentrations of hexavalent chromium in the disposal areas and the clarifier were 18 and 250 mg/kg, respectively. These levels are below or approximately equal to the comparison value for hexavalent chromium (200 mg/kg).

Therefore, while the concentrations of total chromium in some areas of the site are well above background, they are still below levels of health concern because the chromium is mostly in the trivalent form. Regardless, EPA should continue to test for total and hexavalent chromium during the Remedial Investigation of the site to fully characterize the nature and extent of chromium contamination.

(2) Phenols/Cresols

Phenols and cresols are biocides (e.g., fungicides) that are used in the tanning process [21].

The highest concentration of pentachlorophenol (510 mg/kg) was almost 100 times greater than its comparison value (6 mg/kg). Pentachlorophenol was also detected in the drummed wastes at 28 mg/kg.

Two other phenols or cresols were detected in the sludges with maximum concentrations greater than comparison values: 2,4,6-trichlorophenol (140 mg/kg) and 4-methylphenol (930 mg/kg). The comparison values for these compounds are 60 mg/kg and 390 mg/kg, respectively.

(3) Dioxin

Dioxin is a common impurity in technical-grade pentachlorophenol [25].

Dioxin is actually a class of 30 similar compounds (called "congeners") that share a common mechanism of toxicity [31]. In order to assess the combined effects of all the dioxin congeners, the toxic equivalent (TEQ) concentration of the sample was calculated using the most recent toxic equivalency factors from the World Health Organization [32].

In 2000, the sludges from Area I, Area II, and the former clarifier facility were tested for dioxins [12,13]. The average dioxin TEQ concentrations in Area I (110 nanograms per kilogram, or ng/kg(1)) were much lower than those from Area II (2,630 ng/kg), but still greater than ATSDR's comparison value for residential soils (50 ng/kg). The TEQ of the clarifier sludge (73 ng/kg) was similar to Area I. In Areas I and II, 52-71% of the dioxin TEQ was from two congeners: 1,2,3,6,7,8-Hexachlorodibenzodioxin and 1,2,3,4,6,7,8-Heptachlorodibenzodioxin. The most potent congener, 2,3,7,8-Tetrachlorodibenzodioxin, accounted for only 5% of the TEQ on average.

The 2000 test results confirm the findings of the 1986 site investigation that tested for dioxin in sludge from various locations, including Areas I and II [3]. In the 1986 tests, dioxin was not detected in Area I, but was found in Area II at a maximum possible TEQ(2) of 13,300 ng/kg. In other disposal areas onsite, the maximum possible dioxin TEQ was in 5.76 ng/kg. Most of the dioxins and furans that were detected in 1986 were in the hexachlorinated and heptachlorinated congener groups. Tetrachlorodibenzodioxins and furans were not detected in any of the 1986 samples.

(4) Other Compounds

In the sludge and waste, the maximum concentrations of arsenic (35.6 mg/kg) and some individual polycyclic aromatic hydrocarbons (PAHs) (e.g., 0.54 mg/kg for benzo[a]pyrene) were higher than their comparison values (0.5 mg/kg for arsenic, 0.1 mg/kg for benzo[a]pyrene). However, the measured concentrations are essentially equal to background levels for these compounds. In New Hampshire, the background concentration of arsenic in soil is 11 mg/kg [18]. The average arsenic concentration in Areas I, II, VI, and VII from the Weston Site Investigation in 1989 was 12.2 mg/kg. In the clarifier sludge, the maximum arsenic concentration was 15 mg/kg. The background level for total PAHs (i.e., the sum of the individual PAH compounds) is 25 mg/kg for urban areas in New England [22]. The maximum concentration of total PAHs in sludge (8.2 mg/kg) was lower than this background level.

Naphthalene and hexachlorobenzene were both detected in drummed wastes. The maximum concentration of naphthalene (1,100 mg/kg) was slightly higher than its comparison value (1,000 mg/kg). Similarly, the comparison value for hexachlorobenzene is 0.4 mg/kg and the maximum concentration detected was 0.51 mg/kg. The drums in which these chemicals were detected have subsequently been removed from the site.

(C) Soil

(1) Northern Parcel

The only time soil (not sludge) on the site was tested was in 2000 when the sandy layer of fill material above the sludge in Area II was tested for total chromium [13] (Table 4). The maximum total chromium concentration in the sand was 1,800 mg/kg. Based on the sludge data, it is reasonable to assume that the chromium in the sand is in the less toxic trivalent form. The comparison value for trivalent chromium in soil is 80,000 mg/kg. Therefore, the chromium in the sandy layer is expected to be below a level of health concern.

The few soil tests that have been done in Area II are not sufficient to characterize the entire site. Without soil tests across the site, it cannot be verified that exposures to contaminated soils are not occurring. This is especially important in the area near the main facility where several businesses currently operate. There are no data to show whether or not the soils in this area are contaminated.

(2) Southern parcel

Although there has been limited soil testing onsite, there have been scores of test pits and borings to identify the areas of waste disposal. No sludge or waste was encountered in the 19 borings and test pits on the southern parcel [1,2]. Moreover, there is no record that wastes were handled or disposed on the southern (undeveloped) parcel [1]. Therefore, no soil contamination is expected on the southern parcel.

(D) Nashua River Surface Water

Water in the Nashua River near the site was tested in July and September 1985 [2]. Samples were collected from three locations along the edge of the site and tested for metals, VOCs, and acid-extractable organics. Three compounds were detected in these samples at concentrations greater than comparison values: arsenic (max: 2 micrograms per liter, or ug/L), silver (max: 60 ug/L), and methylene chloride (max: 9 ug/L) (Table 5).

The arsenic and silver detections in 1985 do not appear to be related to the site. The maximum arsenic concentration (2 ug/L) was equal to background levels in rivers and streams [24]. The highest concentration of silver (60 ug/L) was found upstream of the discharge point for the contaminated wastewater.

Another source of information relevant to Nashua River contamination is an analysis of the tannery wastewater that was discharged to the river. On March 6, 1981, the tannery wastewater was tested for metals, cyanide, phenols, VOCs, acid-extractable organics, base-neutral extractable organics, pesticides, and polychlorinated biphenyls [8] (Table 6). The only compound detected at concentrations greater than comparison values for drinking water was methylene chloride at 177 ug/L. The comparison value for this compound is 5 ug/L.

Based on tests of tannery wastewater and river water samples, contamination of surface water in the Nashua River appears to have been relatively low and limited to methylene chloride. However, both tests were done in the 1980s by which time the wastewater was treated onsite before discharge. Therefore, these results may not be representative of conditions in the past before the on-site treatment systems were in operation.

(E) Nashua River Sediment

In 1993, 20 sediment samples were collected from the river and the tannery wastewater discharge pipe and were tested for chromium, cadmium, lead, and phenols [7] (Tables 7 and 8). The sample from the discharge pipe was expected to have the highest contamination.

For total chromium, the concentrations were higher in the discharge pipe (3,290 mg/kg) than in the river (313 mg/kg, max). The chromium concentrations were also higher in the downstream sediments than those collected upstream of the discharge point. Based on these measurements, DES concluded that there had been a release of chromium to the river that had resulted in elevated chromium concentrations in the sediments. The chromium in the sediments is expected to be mostly in the trivalent form, and the concentrations are below the comparison value for trivalent chromium (80,000 mg/kg).

Cadmium was the only other compound detected above a health comparison value. The maximum cadmium concentration in the river sediments was 18.7 mg/kg. However, the average cadmium concentration in the river sediments (5 mg/kg) and the cadmium concentration in the discharge pipe (3.5 mg/kg) were both less than the comparison value (10 mg/kg). Therefore, the average cadmium concentrations in the river appear to be below levels of health concern.

Pentachlorophenol (or other phenols/cresols) was not detected in any sediment samples (at a measurement sensitivity of 0.4-9.6 mg/kg).

The sediments were not tested for dioxin. However, the likely source of dioxin at the site is from trace contamination of technical grade pentachlorophenol. Since pentachlorophenol was not detected in the sediments, it is unlikely that the sediments would contain significant dioxin contamination.

(F) Nashua River Fish

In October and November 1986, fish were collected from the Nashua River and analyzed for dioxins [4] (Table 9). This was prompted by the detection of dioxin in onsite sludges earlier that year, including sludges in the outfall leading directly to the river. The fish were collected with a gillnet from three stations: one-half mile upstream of the site, at the site, and downstream of the site. Although one station was upstream of the site, the researchers acknowledged that fish could easily travel between the three stations. At each station, three white suckers (aged 4-9 years old) were taken and composited into a single homogeneous sample. Older white suckers were chosen as the test species because they are a bottom feeder which tends to bioaccumulate toxins such as dioxin.

The most potent congener group, Tetrachlorodibenzodioxins, was not detected in the fish samples at detection limits of 3.7-6.1 ng/kg (parts-per-trillion). The only congener group detected was Tetrachlorodibenzofurans, which had concentrations ranging from 56 ng/kg upstream, 71 ng/kg near the site, to 54 ng/kg downstream of the site. The results of the study were reported as congener groups, not individual congeners. Therefore, it could not be verified whether the toxic "2,3,7,8" isomer of this dioxin group was present in the samples. The comparison value for Tetrachlorodibenzofurans in fish tissue is 0.21 ng/kg.

 

Dioxin has many sources in the environment. In the late 1980s (the same time that the fish near Mohawk Tannery were tested), EPA completed the National Study of Chemical Residues in Fish. The purpose of the study was to measure toxic pollutants (including dioxins) in benthic and game fish nationwide. For 2,3,7,8-TCDF, a member of the tetrachlorodibenzofurans congener group, the average and maximum concentrations were 13.6 and 404 ng/kg, respectively. At the Mohawk Tannery site, the average concentration of TCDF congeners was 60 ng/kg. This congener was detected in 89% of all the sites tested nationwide. The EPA report showed that pulp and paper mills using chlorine bleach pulp appeared to be the dominant source of dioxins in fish [26]. Therefore, the relationship between the contamination at the Mohawk Tannery site and the dioxin in fish from the Nashua River is unclear.

(G) Groundwater

Groundwater monitoring wells were installed and tested in 1984 and 1985 [1,2]. Samples from these wells have been tested for VOCs, metals, and acid-extractable organics. The compounds that have been detected in the groundwater are listed in Table 10.

The metal with the highest concentration relative to its comparison value is arsenic. The maximum concentration of arsenic was 1,000 ug/L and the current N.H. drinking water criterion is 10 ug/L. Since arsenic was not a major contaminant detected in the sludge, the likely source of this arsenic is arsenic minerals in the soil that have been dissolved under the anaerobic conditions beneath the lagoons.

Several chlorinated solvents were also detected in the groundwater. Tetrachloroethene, trichloroethene, and 1,2-dichloroethane had maximum concentrations of 250, 30, and 86 ug/L, respectively.

Groundwater flow beneath the site is in a south or southwest direction, toward the Nashua River and away from the community. Therefore, residents near the site should not be exposed to contaminated groundwater. Furthermore, the majority of residents within 4 miles of the tannery (97%) obtain drinking water from municipal supplies [8].

In 1994, DES contacted the local water company in order to identify any private wells in the vicinity of the site. The water company found several homes in the area that potentially had private wells. DES surveyed the owners of these homes and discovered that two of the homes did, in fact, use private wells for drinking water (18 Bitirnas St., 28 Bitirnas St.). Even though these wells were far upgradient from the site, DES tested them in October 1994 for metals and VOCs. No compounds were detected [8]. DES plans to test the water from these two wells again in 2001.

A third private well was brought to the attention of DES during a public meeting in February 2001. This well, located at 2 Tampa Street, will be tested by DES in 2001. No contamination is expected because of its location relative to the site. However, DHHS supports testing private wells near the site as a prudent precaution.

(H) Ambient Air

While the tannery was in operation, residents in the community could often smell odors coming from the site. In 1977, consultants for the City of Nashua concluded that the main source of these odors was hydrogen sulfide [14]. In a typical tannery, to remove hair from the hides, the hides were first treated with an alkaline solution of calcium hydroxide (lime), sodium sulfhydrate, and sodium sulfide. The hides were later treated with a sulfuric acid solution to prepare them for the tanning agent [21]. Mixing the alkaline and acidic wastes from these treatments would have produced hydrogen sulfide gas.

The odors have decreased since the tannery closed in 1984. However, the residents report that on occasion they still smell odors from the site. The sludge in the Area I lagoon and other disposal areas contain high concentrations of hydrogen sulfide. If this sludge is disturbed in the future for remediation, EPA and DES plan to control hydrogen sulfide gas emissions to prevent strong odors.

In addition to hydrogen sulfide, other compounds could have contributed to the odors. At a former glue manufacturing plant where decaying animal hide piles produced odors, it was determined that reduced sulfur compounds such as methyl mercaptan were contributors to the smell. Another chemical than may have caused odors is ammonia, which is produced when organic matter (e.g., animal hides) decompose [14].

There have not been any reports of large amounts of dust blowing off the site. Consequently, exposure to the major site contaminants - chromium, pentachlorophenol, and dioxin - from inhaling airborne particulates is not a concern at this site.

Therefore, based on the tannery manufacturing process, an odor investigation in 1977, and experience at similar sites, the likely source of odors at the site are hydrogen sulfide, methyl mercaptan, ammonia, and related compounds. However, no recent or historic air sampling data are available to document the concentrations of these compounds in the air on the site or in the site vicinity.

(I) Asbestos Waste Landfill

At the end of Intervale Street, there is a landfill of asbestos-containing material (ACM). This landfill (sometimes called the "Sprague property") is partially located on the Mohawk Tannery site. It was created in 1983 when the EPA covered 2-5 feet of ACM wastes with 2 feet of sand and gravel and 1 foot of topsoil and grass [2]. As long as the ACM remains covered, there is no exposure and, consequently, no public health hazard.

This landfill is one of hundreds like it in the Nashua area. ACM wastes from the Johns Manville asbestos manufacturing facility in Nashua were given away as fill material. Many people used this fill in their yards. In the 1980s, EPA removed much of the ACM fill from residential properties and buried it in small landfills in the area. The ACM landfill on the Sprague property was one of these small landfills.

The DES Solid Waste Compliance Bureau is responsible for managing these ACM landfills. Each landfill is inspected every two years, or more frequently if necessary. Inspectors confirm that the cap over the ACM is still intact and note any erosion or land use changes that might indicate a potential hazard in the future. The landfill at the end of Intervale Street, as well as several other ACM landfills near the Fimbell Door Landfill, were last inspected in 1999. For more information on the DES program and the laws governing ACM landfills, contact the DES Solid Waste Compliance Bureau at 271-2925.

(J) Physical Hazards

A physical hazard is something that is capable of causing immediate physical injury. For example, high stacks of drums, deep holes with steep sides, and structurally unstable buildings would be considered physical hazards.

(1) Clarifier Tank

In the former clarifier facility, there is a concrete tank with dimensions of 20 feet wide, 60 feet long, and 8-10 feet deep. Until recently, this tank was partially filled with contaminated water and sludge. If a person fell into this tank, it would be nearly impossible to get out without aid.

In 2000, EPA removed all the water and sludge from the tank, placed a plastic fence around the edge of the tank, and boarded up the building to prevent people from gaining access to it. These controls will protect the public from this hazard in the near term, but must be maintained in the future until the tank is removed.

(2) Collapsed Section of Tannery Building

The roof on the southern wing of the main building has collapsed. Inside this section of the building there are hanging pipes and beams, debris, and some asbestos-containing material. In 1999, tests showed that the former tannery building had asbestos in wallboard (33% amosite), transite board (15% chrysotile), and pipe wrap (25% amosite, 10% chrysotile) [9]. Some of these asbestos-containing materials were in friable condition. When asbestos-containing material is friable, the asbestos fibers are loose and can become airborne. In contrast, non-friable asbestos fibers are bound in the material which prevents exposure.

EPA removed the friable material from the intact portions of the building during the time-critical removal action in 2000. However, EPA did not remove asbestos-containing material from the collapsed portion of the building because this area was not structurally sound.

The collapsed portion of the building is approximately 50 feet from the nearest residence. There is a fence around the site to keep trespassers out, but the gate to the site is often left open. According to EPA, the asbestos-containing material in this area is non-friable and, therefore, not currently a health hazard. For non-friable ACM, the asbestos fibers are encapsulated by the material and, therefore, cannot become airborne and inhaled. However, if this material remains exposed to the elements for an extended period of time, the material may break down and asbestos fibers may become loose and be carried by the wind into the nearby community.

Therefore, the collapsed portion of the building is a physical hazard. Trespassers in this area could be physically harmed by sharp debris or a complete collapse. Asbestos-containing material in the area is not a hazard currently but could become friable in the future if left exposed to the elements.

(3) Open Lagoon in Area I

The lagoon in Area I contains standing water most of the year. The sediments in the lagoon are very soft and several feet deep. Therefore, the lagoon in Area I may be a physical hazard to trespassers because, if they fall into the lagoon, they may not be able to get out without assistance.


IV. PATHWAYS OF HUMAN EXPOSURE

(A) Completed Exposure Pathways

Environmental contamination cannot affect a person's health unless he or she comes into contact with it. Likewise, human contact with environmental contamination is only possible when a completed exposure pathway exists. A completed exposure pathway exists when all of the following five elements are present: (1) a source of contamination; (2) transport through an environmental medium; (3) a point of exposure; (4) a route of human exposure; and (5) an exposed population. For the Mohawk Tannery Site, the completed exposure pathways are listed in the following table.

Completed Exposure Pathways

Name Source Environmental Transport and Media Exposure Point Exposure Route Exposed Population Time Frame
Onsite Trespasser Pathway Tannery Waste Sludge, Soil, and Waste Onsite, in lagoons and disposal areas Ingestion
Dermal
Trespassers on the site Past
Present
Future
River Water/ Sediments Pathway Tannery Waste Sediments and Surface Water Nashua River Ingestion
Dermal
Swimmers
Waders
Past
Present
Future
Fish Consumption Pathway Tannery Waste Fish Tissue Nashua River Ingestion People who eat fish from this river Past
Present
Future
Ambient Air Pathway Tannery Waste Ambient Air Odors Community east of the site Inhalation Residents in this community Past
Present
Future

In the following sections, each of these completed pathways of exposure will be outlined in more detail. The public health implications of the exposures will be evaluated in the Discussion section.

(1) Onsite Trespasser Pathway

There is evidence that people trespass on the site despite the perimeter fence. These people could be exposed to contaminants in the sludge lagoon in Area I. The other disposal areas are covered with sand so the sludge in these areas cannot be contacted under current conditions. Due to the properties of the chemicals, most of the exposure would occur from ingesting small amounts of soil and waste.

(2) Nashua River Water and Sediments Pathway

During the tannery operations, wastewater was discharged to the Nashua River. Elevated concentrations of chromium have been detected in the river sediments as a result. Therefore, children or adults periodically wading or swimming in the river near the site could have been exposed to contaminants that accumulated in the sediments or the water. The route of exposure would have been ingestion of small amounts of sediment that stuck to a person's hands, ingestion of small amounts of water, and, to a lesser extent, absorption of chemicals through bare skin.

(3) Fish Consumption Pathway

People who eat fish from the portion of the Nashua River near the Mohawk Tannery site could be exposed to dioxins in the fish tissue.

(4) Ambient Air Pathway

Some residents have experienced odors from the site. These odors were greatest when the tannery was still operating (before 1984) but are still reported by some residents. Based on the tannery manufacturing process, an odor investigation in 1977, and experience at similar sites, the likely source of odors are hydrogen sulfide, methyl mercaptan, ammonia, and related compounds. However, no recent or historic air sampling data are available to document the concentrations of these compounds in the air on the site or in the site vicinity. If the sludges in Areas I and II are disturbed in the future, EPA and DES plan to control hydrogen sulfide emissions to prevent the strong odors from recurring.

(B) Potential Exposure Pathways

Potential exposure pathways are routes along which exposure could be possible except that one or more of the five critical elements is missing. In some cases, this means that the exposure is not possible now but may be possible if conditions change in the future. In other cases, an exposure may be possible but cannot be confirmed because data are not available. The potential exposure pathways that exist at the Mohawk Tannery are summarized in the following table.

Potential Exposure Pathways

Name Source Environmental Transport and Media Exposure Point Exposure Route Exposed Population Time Frame
Residential Use Pathway Tannery Waste Sludge and Soil Onsite, in lagoons and disposal areas Ingestion
Dermal
Potential future residents onsite Future
Onsite Worker Pathway Tannery Waste Waste and Soil Onsite, near buildings Ingestion
Dermal
Workers at businesses on the site Past
Present
Future
Future Flood Pathway Tannery Waste Sediments and Surface Water Nashua River Ingestion
Dermal
Residents downstream during a flood Future

(1) Future Residential Use Pathway

The site is zoned for residential use and is abutted by residential properties. If the site were redeveloped as a residential property, the future residents would be exposed to chemicals in Area I and the other disposal areas onsite.

(2) Onsite Worker Pathway

Several businesses currently occupy space in the former tannery facility. Employees of these businesses may be exposed to soil contamination and waste due to the former tannery operations. The soil around the former tannery facility has not been tested for contaminants. Therefore, it is not known whether or not contamination is present in the area where the businesses are operating.

(3) Future Flood Pathway

The sludge in Areas I and II has been placed unsecured into lagoons in the 100-year floodplain for the Nashua River. A major flood could wash these sludges into the river, which would contaminate the river sediments. Soils in the floodplain of the river could also become contaminated as a result. Downtown Nashua is one mile downstream of the site.

(C) Eliminated Exposure Pathways

DHHS considered three other pathways of concern. Exposures through these pathways are not possible. Therefore, these pathways were eliminated from further evaluation.

Eliminated Exposure Pathways

Name Source Environmental Transport and Media Exposure Point Exposure Route Exposed Population Time Frame
Private Well Pathway Tannery Waste Private wells Tap water Ingestion
Dermal
Inhalation
Residents with private wells Past
Present
Future
Undeveloped Southern Parcel Pathway Tannery Waste Soil Wetlands south of the Tannery Ingestion
Dermal
Neighbors who use this area Past
Present
Future
Asbestos Landfill Pathway Asbestos Waste Ambient Air "Sprague" property Inhalation Neighbors who use this area Future

(1) Private Well Pathway

Groundwater flow beneath the site is in a south or southwest direction, toward the Nashua River and away from the community. Therefore, residents near the site should not be exposed to contaminated groundwater. Furthermore, the majority of residents within 4 miles of the tannery (97%) obtain drinking water from municipal supplies [8]. The few private wells in the vicinity of the site have been or will soon be tested by DES.

(2) Undeveloped Southern Parcel Pathway

There is no evidence of soil contamination on the undeveloped southern portion of the site. Therefore, if people enter this area on foot, they would not be exposed to contamination.

(3) Asbestos Landfill Pathway

At the end of Intervale Street, there is a small landfill of buried asbestos-containing material (ACM). Currently, the ACM waste is covered by several feet of soil so there are no exposures to it. DES staff visit this landfill every 2 years to ensure that the soil covering it remains in place. As long as this management practice is maintained, there will be no exposure to this waste.


V. DISCUSSION - ADULT AND CHILDREN'S HEALTH ISSUES

Based on the review of environmental data and conditions at the site, there are several completed and potential pathways by which people could be or could have been exposed to chemicals from the site. In the following sections, the public health implications of these exposures will be discussed.

  • In Section A, the actual or potential exposures to these chemicals will be evaluated using estimates of exposure and the toxicological and epidemiological data available for these chemicals. As part of the ATSDR Child Health Initiative, the susceptibility of young children to the chemical exposures will be a large component of the toxicological and epidemiological review.
  • In Section B, data on cancer diagnoses for the community near the site and the Town of Nashua will be presented.
  • Finally, health questions from the community are answered in Section C.

The combination of these different evaluations provides the weight of evidence to support DHHS' determinations regarding public health hazards associated with exposures.

(A) Public Health Implications of Exposure

In this subsection, we discuss the known adverse health effects that have been associated with the types of exposures that are or were possible at this site. To understand how adverse health effects could be caused by a specific chemical, it is helpful to review factors related to how the body processes such a chemical. Those factors include the exposure concentration (how much), the duration of exposure (how long), the route of exposure (breathing, eating, drinking, and/or skin contact), and the multiplicity of exposure (combinations of contaminants). Once exposure occurs, a person's individual characteristics such as age, gender, diet, general health, lifestyle, and genetics, influence how the body absorbs, distributes, metabolizes, and excretes the chemical. Together these factors determine the potential health effects that can be caused by the chemical.

To evaluate potential health effects, ATSDR has developed Minimal Risk Levels (MRLs) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of daily human exposure to a contaminant that is likely to be without a measurable risk of adverse, non-cancerous effects. MRLs are developed for oral and inhalation exposure routes, and for different durations of exposure (acute: 14 days or fewer; intermediate: 15-364 days; chronic: 365 days or more). Acute MRLs are typically higher than chronic MRLs because of the shorter duration of exposure.

ATSDR publishes MRLs in its series of chemical-specific documents called Toxicological Profiles - documents that describe health effects, environmental transport, human exposure, and regulatory status of a chemical. The preparers of this Public Health Assessment have reviewed the profiles for the contaminants of concern at the site.

We may also use EPA's chemical specific Reference Doses (RfDs) and Reference Concentrations (RfCs) to determine if non-cancer health effects are possible. RfDs, which are analogous to ATSDR's MRLs, are estimates of daily human exposure to a contaminant that is unlikely to result in adverse non-cancer health effects over a lifetime. For chemicals that are considered to be known, probable, or possible human carcinogens, DHHS uses EPA's chemical-specific cancer potency values to determine a theoretical estimate of excess lifetime cancer risk associated with exposure to the contaminant.

In the following subsections, the completed and potential pathways of exposure will be evaluated in detail.

(1) Completed Exposure Pathways

There are four completed pathways of exposure at the site. These are ways people have been or are being exposed to contamination at the site.

  • Onsite Trespasser Pathway
  • Nashua River Water and Sediments Pathway
  • Fish Consumption Pathway
  • Ambient Air Pathway

(i) Onsite Trespasser Pathway

One quarter of the community members who completed the DHHS survey indicated that they walk on the Mohawk Tannery property (Appendix D).

Someone walking (trespassing) on the site could be exposed to contaminants in soil by ingesting small amounts of contaminated soil or waste on their hands. To a lesser extent, some of the chemicals could also be absorbed through the skin. Adolescents are the most likely population to trespass on the site. Therefore, DHHS used exposure parameters for adolescents from EPA and DES guidance documents to estimate the exposures [18-20]. These exposures were assumed to continue over 9 years because this is the median amount of time that Americans live in one place [19].

The only chemical of potential concern for people who trespass on the site is dioxin. For the other contaminants in the sludges, typical exposures would have been less than levels thought to be without risk of adverse effects (e.g., Minimal Risk Levels from ATSDR or Reference Doses from EPA). See Table 11 for a summary of estimated exposures to each contaminant compared to health comparison values.

(a) Dioxin

The maximum concentration of dioxin detected on the site (4,598 ng/kg) is in the buried sludges in Area II. However, exposure to these sludges is not currently possible unless someone were to dig through 1-2 feet of soil. In Area I, the only area where sludges are accessible, the dioxin concentration was 156 ng/kg. Exposure to this concentration of dioxin while trespassing would result in an exposure of 0.04 picograms(3) per kilogram per day (pg/kg-d) which is well below ATSDR's Minimal Risk Level of 1 pg/kg-d.

Moreover, ATSDR's experience with dioxin is that residential exposures to soil with 1,000 ng/kg (1 part-per-billion) or less of dioxin do not produce increased body burdens or any indication of adverse health effects. The maximum concentration of dioxin in Area I is 156 ng/kg, which is well below 1,000 ng/kg.

Therefore, people who contact dioxin in the sludge while trespassing on the site are not likely to experience any adverse health effects. This conclusion is consistent with the 1986 ATSDR Health Consultation regarding the 1986 dioxin testing results [11] and the 2001 ATSDR Health Consultation regarding the characterization of sludges in Areas I and II in 2000 [17].

(ii) Nashua River Water and Sediments Pathway

According to the DHHS survey, a few community members (9.1% of respondents) swim or wade in the Nashua River, although not necessarily in the area by the site (Appendix D).

People who wade or swim in the Nashua River near the site could be exposed to site contaminants in sediments, and possibly surface water. DHHS estimated these exposures using similar assumptions as were used to evaluate the trespasser pathway. However, exposures to contaminants in both sediment and water were combined.

The combined exposures to contaminants detected in the river were below levels of health concern (e.g., Minimal Risk Levels or Reference Doses) (See Table 12). Arsenic and methylene chloride are known or probable human carcinogens. However, exposures to these compounds in the river would not result in a significant increased risk of cancer, based on theoretical cancer potency factors from EPA.

Therefore, people who swim or wade in the section of the Nashua River near the site are not likely to experience any adverse health effects as a result.

(iii) Fish Consumption Pathway

None of the survey respondents reported eating fish from the Nashua River, but some stated that they engage in sport fishing (Appendix D).

Dioxins are the only contaminants that have been measured in fish from the river near the site. See Table 13 for estimates of exposure to dioxins from eating the fish from the Nashua River.

(a) Dioxin

In 1986, tetrachlorodibenzofurans (TCDF) were detected in the fish in the river near the site at concentrations between 54 and 71 ng/kg. These concentrations were elevated above background (13.6 ng/kg) but the source of the dioxin is unclear.

In the area near the site, there is no evidence of subsistence fishermen who rely on sport fish as a major component of their diet. Consequently, it is appropriate to estimate exposures using the average amount of sport-caught freshwater fish eaten by a recreational fisherman (approximately 6.5 pounds per year, which averages out to 8 grams per day) [20]. The likely exposures to TCDF from consuming fish at this rate would be 9.5 picograms per kilogram per day (pg/kg-d), which is less than the Minimum Risk Level for TCDF (10 pg/kg-d)(4). Moreover, 9.5 pg/kg-d is an overestimate of actual exposure at the Mohawk Tannery site because fishermen would not exclusively eat fish caught from the Nashua River. Therefore, based on the available data, exposures to dioxin from eating fish from the river near the site are not likely to result in adverse health effects.

Although unrelated to the Mohawk Tannery site, DHHS has a state-wide advisory for the consumption of freshwater fish from New Hampshire water bodies to protect the public from mercury, a contaminant that is found in fish throughout the state. The general population is advised to limit their consumption of freshwater fish to four 8-ounce meals per month. Young children (under 7 years old) should eat only one 3-ounce meal per month. Finally, women who are pregnant, or who may become pregnant, and women who are breastfeeding their children should eat only one 8-ounce meal of freshwater fish per month. However, it is important to remember that fish is still an important part of a healthy diet. Fish are high in protein and low in saturated fat and cholesterol.

(iv) Ambient Air Pathway

Approximately one-half of the survey respondents reported smelling odors from the site (Appendix D). The odors were generally described as "sulfuric" and "nauseating".

The likely source of odors at the site are hydrogen sulfide, methyl mercaptan, ammonia, and related compounds. From the time of tannery operations through the present, residents in the neighborhood could have been exposed to these compounds in air. The following sections contain more information on these compounds. However, no recent or historic air sampling data are available to document exposure concentrations currently or in the past.

(a) Hydrogen Sulfide

Hydrogen sulfide has a "rotten-egg" smell and can be an irritant to the eyes, lungs and respiratory tract. It is created naturally by the breakdown of organic matter. It is also found in human and animal waste, such as near sewage treatment facilities or livestock manure areas. People can smell minute amounts of hydrogen sulfide - sometimes at concentrations as low as 0.5 parts-per-billion (ppb) in air [27].

While people can smell very low concentrations of hydrogen sulfide, exposures that can seriously affect a person's health occur at higher concentrations. In two laboratory experiments, healthy persons experienced no significant health effects when exposed to hydrogen sulfide concentrations of up to 5,000 ppb. Some asthmatics have experienced mild bronchial restriction at 2,000 ppb. Hydrogen sulfide has not been shown to cause cancer in humans [27].

Some sensitive populations may experience symptoms at lower concentrations. At concentrations near 50 ppb, the odor can be offensive for some people which can trigger nausea and headaches. These are not long-term health effects, and will go away if the odor is stopped or the person leaves the area. There are also many other causes of nausea and headaches besides hydrogen sulfide odors. A series of studies in polluted communities in Finland found associations between low-level hydrogen sulfide exposures (less than 40 ppb) and cough, breathlessness, wheezing, headaches, and eye-nose-throat irritation. However, these communities were exposed to a combination of reduced sulfur compounds, particulate matter, and sulfur dioxide, not just hydrogen sulfide [27]. Asthmatics are anticipated to be more sensitive to hydrogen sulfide exposures than the general population [27].

Residents have reported that, although odors are still noticeable on occasion, the strong odors occurred in the past when the tannery was operating. The hydrogen sulfide concentration in the air that caused the past odors is unknown. For reference, the concentration of hydrogen sulfide in the air around landfills is typically 15 ppb [37]. The highest concentration of hydrogen sulfide in "severely polluted" towns with pulp mills in the South Karelia Air Pollution Study was 40 ppb [27]. Considering mixing and dilution in the atmosphere, there is no reason to expect that the concentrations near the Mohawk Tannery site would have been significantly higher than have been observed at these other sites.

Therefore, exposures to hydrogen sulfide in the air near the site are unlikely to result in any long-term, serious, adverse health effects. However, sensitive individuals may have experienced acute symptoms, such as nausea, headaches, cough, wheezing, and eye-nose-throat irritation, from past exposures when the odors were very strong. If the sludges onsite are disturbed in the future, EPA and DES plan to control hydrogen sulfide emissions in order to keep the concentration of this gas in the surrounding community below levels of health concern and to eliminate odors to the greatest extent possible.

(b) Methyl Mercaptan

At the Industriplex Site in Woburn, Massachusetts, decaying animal hides left at an abandoned glue manufacturing plant produced odors [34]. Hydrogen sulfide and methyl mercaptan were identified as the probable sources of the odors. The concentration of hydrogen sulfide in the hide piles was 100 times greater than the concentration of methyl mercaptan. Therefore, while methyl mercaptan likely contributed to the odors, the predominant source of the odors at this site was hydrogen sulfide.

Methyl mercaptan (also known and methanethiol) contains reduced sulfur atoms like hydrogen sulfide. It has a putrid smell, like rotten cabbage, that can be detected at concentrations as low as 1.6 ppb [28]. Exposure to elevated concentrations of methyl mercaptan can cause similar effects as hydrogen sulfide, but methyl mercaptan is less toxic than hydrogen sulfide [35].

Therefore, like hydrogen sulfide, if methyl mercaptan was the source of the odors in the past, it is unlikely that exposures to this compound in the air would cause any long-term adverse health effects. Methyl mercaptan is less toxic than hydrogen sulfide and, based on tests at the Industriplex site, unlikely to have higher concentrations than hydrogen sulfide.

(c) Ammonia

Ammonia is a colorless gas with a sharp odor. The odor is familiar to most people because ammonia is used in household cleaners [29]. Ammonium sulfate and ammonium chloride are used in one step of the tanning process [21].

Ammonia is an upper respiratory irritant in humans. Exposures to levels exceeding 50,000 ppb result in immediate irritation to the nose and throat; however, tolerance appears to develop with repeated exposure. ATSDR has derived a Minimal Risk Level of 300 ppb for chronic exposures. This is based on a study that found that chronic exposure to 12,500 ppb of ammonia in air had no effect on pulmonary function or odor sensitivity in a group of workers in a soda ash factory [29].

Significant concentrations of ammonia in the ambient air are only expected near ammonia production plants, ammonia transport or storage facilities, and farm fields after fertilizer is applied [29]. Therefore, it is unlikely that past exposures to ammonia in the air near the site were high enough to result in long-term, adverse health effects.

(2) Potential Exposure Pathways

DHHS has identified three potential pathways of exposure at the site. These are ways that people might be or might have been exposed to contaminants; however, either conclusive evidence of exposure is lacking or the exposure has not yet occurred.

  • Future Residential Use Pathway
  • Onsite Worker Pathway
  • Future Flood Pathway

(i) Future Residential Use Pathway

Frequent exposures to contaminated sludges would be possible if the site were redeveloped for residential housing or other uses (e.g., a park). Exposures to the buried sludges would be possible because development of the property would likely involve excavating into areas with sludge to install basements, utility corridors, and landscaping.

For a young child, residential exposures to the maximum detected concentration of dioxin in Area II (4,598 ng/kg) would be approximately 100 times greater than ATSDR's chronic Minimal Risk Level. This could lead to an increased body burden of dioxin and, potentially, to adverse health effects. The increased risks of developing cancer from such an exposure would be moderate to high, and would exceed EPA's acceptable risk range of 1 in 10,000 to 1 in 1,000,000.

Exposures to other contaminants in the sludge would incrementally increase the health risks from exposure. However, the greatest risks would be from dioxin.

Therefore, potential future residents of the site would be exposed to concentrations of dioxin that could produce adverse health effects.

(ii) Onsite Worker Pathway

Several businesses occupy space in the former tannery building. Workers at these businesses might be exposed to contamination from the former tannery operations. No environmental tests have been done in the area used by the businesses. Therefore, it is uncertain whether the occupants are being exposed to chemicals in this workplace. Environmental tests are needed to resolve this uncertainty.

(iii) Future Flood Pathway

Sludges in the two onsite lagoons (Areas I and II) are in the 100-year floodplain of the Nashua River. If a 100-year flood were to occur, the contaminated sludges could be washed into the river. This would lead to increased exposures to contaminants in the sediments and water. Also, contamination would be deposited in presently uncontaminated areas across the floodplain. Since downtown Nashua is only one mile downstream of the site, it would be prudent to remove the sludges from these areas as soon as possible to eliminate the chance that this event might occur.

(3) ATSDR Child Health Initiative

Children are at a greater risk than adults from certain kinds of exposure to hazardous substances emitted from waste sites. They are more likely to be exposed for several reasons (e.g., they play outdoors more often than adults, thus increasing the likelihood that they will come into contact with chemicals in the environment). Due to their smaller stature, children may breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in higher doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if certain toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care.

At the Mohawk Tannery Site, children are more likely to be exposed to contaminants because children, not adults, are more likely to trespass on the site. To account for this, DHHS used exposure factors for children/adolescents when estimating exposures for people who trespass on the site or who play in the Nashua River near the site.

(B) Health Outcome Data Review

A health outcome data review is used to determine the general status of a community's health. The objective is to determine if the rates of disease in a community are higher than expected for that community using data for the State as a comparison.

(1) Methodology

The health outcome evaluation for the Mohawk Tannery Site is based on an analysis of cancer data from the New Hampshire State Cancer Registry (NHSCR). The NHSCR maintains statistics for twenty-three types of cancer in New Hampshire [38]. Cancer information for Nashua, NH was requested for the types of cancer that are known or suspected to be related to the primary contaminants of concern at the Mohawk Tannery site. The cancers for which data were requested and received are: Non-Hodgkins lymphoma, stomach, lung, buccal cavity, pancreas, multiple myeloma, thyroid, leukemia, rectal, kidney, bladder and liver.

Cancer data was requested for a five year time period (1993 through 1997) from the Bureau of Health Statistics and Data Management, which maintains all data files that are disseminated from the NHSCR. The five-year time period that was requested was used for three main reasons; (1) to ensure that disease trends can be calculated and adequately evaluated for a relatively small population both state-wide and for the city of Nashua, (2) taking into account the latency period involved with most cancers (between 10-30 years), the most recent five-year time period will give a good cross-section of data for a time period when it is expected that most excess cases of cancer would present, and (3) this specific five-year period was needed to match with data that were used for the standard comparison population.

Due to the fact that the population of Nashua (1999 Office of State Planning estimate: 83,900) makes up approximately 7% of the total state population (1999 Office of State Planning estimate: 1,201,000), published cancer rates for the State of New Hampshire could not be used as a comparison since they contain so many cases from Nashua. Instead, data used for estimates of United States' cancer rates were obtained from the Surveillance, Epidemiology and End Results (SEER) program of the National Cancer Institute. These data were used as the comparison group [39]. Specifically, cancer rates for the United States' white population were used as the comparison because this was most consistent with the demographic information derived by the United States Census Bureau for the city of Nashua, in which approximately 95% of the population would be considered white [43]. The SEER program began data collection in 1973 and currently contains over 2 million cases. Incidence data derived from SEER are based on 9 geographic regions (Connecticut, Iowa, New Mexico, Utah, Hawaii - the metropolitan areas of Detroit, Atlanta, San Francisco - Oakland, and Seattle-Puget Sound, which make up 9.5% of the total U.S. population [39].

Once the data were received, it was reviewed for potential data quality issues. After this review, a total of 25 cases were removed from the original data set of 1,703. The data that were removed included all in situ cases of cancer (i.e, cancer cells that have not moved into the surrounding tissues), except for bladder cancer, which has not been removed, following both the state (NHSCR) and national (SEER) reporting methodology used.

The number and percentage of the total for each cancer type reviewed in this analysis are shown in Table 14.

(i) Risk Ratio Analysis

A risk ratio (RR) analysis was completed on the community surrounding the Mohawk Tannery site. The RR evaluates the incidence of cancer among an exposed group as compared to the incidence in a non-exposed group. The exposed, for the purposes of this analysis, were defined as residents living within Nashua city census tracts:

33 011 0104 613
33 011 0104 614
33 011 0104 615
33 011 0104 616
33 011 0104 617
33 011 0104 618
33 011 0104 619
33 011 0104 620

These census tracts are comprised of 579 persons and make up approximately 0.3 miles of area primarily east of the Mohawk Tannery site. The population of Nashua outside of the identified census tracts represents the non-exposed group (1995 New Hampshire Office of State Planning Estimate - 80,791). These census tracts were selected based on the localized nature of the contamination at the site as well as to address residents' concerns about exposures to site contaminants in this neighborhood. Although this determination of the exposed group is crude, it covers the population with the greatest opportunities for exposure to site contaminants. Moreover, there are distinct land boundaries (i.e., a rail road and the Nashua River) that separate the selected census tracts from the rest of Nashua. Further explanation of the RR technique is provided in Appendix C.

(ii) Standardized Morbidity Ratio Analysis

Following the site level analysis, a descriptive epidemiological analysis was conducted at the city level using the Standardized Morbidity Ratio technique (SMR). A detailed discussion of this technique is available in Appendix C. The data were reviewed, for each type of cancer analyzed according to gender and age (0-14, 15-24, 25-34, 35-39, 40-44, 45-49, 50-54, 55-59, 60-64, 65-69, 70-74, 75-79, 80-84, and 85+ years). This process allows for a comparison between the observed number of cancer cases in Nashua, per cancer type, to the expected number of cases derived using the comparison population (U.S. white population).

DHHS relies heavily on the quality of the NHSCR data to conduct descriptive epidemiological analyses for both the SMR and RR calculations. There were no independent interviews of persons living in Nashua and no individual medical record reviews. Therefore, these analyses could be subject to reporting errors (e.g., random misclassification). It should also be noted that the SMR and RR analyses performed are descriptive in nature and should not be confused with an in-depth epidemiological study. An epidemiologial study normally lasts for several years and involves interviews with individual study participants. However, while these methods have limitations, they satisfy the objectives of this public health assessment in that they can determine whether or not potential health impacts around the site would warrant further epidemiological investigation or surveillance.

(2) Results

(i) Risk Ratio Analysis

Too few cases of individual cancer types were observed within the census tracts (8 cases total) to complete statistically meaningful analyses. Therefore, the risk ratio (RR) analysis was performed using all cancer types combined (Table 15). The results of this analysis was that there was no statistically significant difference in cancer incidence in the community living near the Mohawk Tannery as compared to the rest of Nashua.

(ii) Standardized Morbidity Ratio Analysis

Standardized morbidity ratios (SMR) for the city of Nashua as a whole were calculated for each type of cancer. The findings from this analysis are illustrated in Table 16. Rates for the following types of cancer were statistically elevated for the city.

  • Rectal Cancer in males (SMR 1.55) and females (SMR 1.89)
  • Pancreatic Cancer in females (SMR 1.8)
  • Lung Cancer in females (SMR 1.5)
  • Kidney Cancer in males (SMR 1.54)
  • Bladder Cancer in females (SMR 2.16)
  • Buccal Cavity & Pharynx Cancer in females (SMR 1.76)
  • Liver Cancer in females (SMR 2.51)

SMR values in the 1-2 range indicate a weak association. Moderate or strong associations are indicated by SMR values in the 3-5 and 6-8 ranges, respectively (see Appendix C).

(3) Discussion

The risk ratio calculation for all cancer types combined showed no increased risk of cancer for the community near the Mohawk Tannery. However, for the city of Nashua as a whole, several cancer types had slightly elevated rates.

It is unknown why there are excess cancers in Nashua, NH, particularly among the female population. A closer inspection of the age-specific data reveals that the rates seem to be consistently higher among females in the sixth decade of life and older.

Female Cancer Incidence 1993-1997


Trends in the age distribution of cancer cases for the state of New Hampshire minus the city of Nashua were also evaluated and the above-mentioned phenomenon was also apparent. Interestingly, this trend was also seen for males in the two cancers that were elevated, but occurred during the seventh decade of life as opposed to the sixth. Since a diagnosis of cancer is more common in these age categories, the age distributions for the city of Nashua and the SEER data were compared [42]. The age structure of Nashua and the SEER population were similar, and in the 60+ age groups for females, the SEER population was approximately 6% higher than the Nashua population. Therefore, a difference in the age distribution between Nashua and the SEER data is not a likely explanation for the elevated rates in Nashua. Due to the fact that the analyses completed were not based on data that contained information about other risk factors associated with cancer, it is not possible to make any other comparisons between Nashua and the reference population (SEER data).

Cancer is not a single disease, but is made up of over 100 various types [40]. It is characterized by the uncontrolled growth and spread of abnormal cells. It can start in one of many different organs or tissues in the body and if it is not controlled through therapeutic methods, can spread (metastasize) to other organs throughout the body [41]. Based on research studies conducted on humans and animals, it has been determined that a variety of risk factors can be linked to increases in the chance of getting cancer. Risk factors are different for each different type of cancer. However, some factors that are generally accepted to increase the risk of cancer include: tobacco smoking, family history of cancer, gender, race, certain hormones in the body, viruses, nutrition, exposure to radiation or some chemicals, sexual behavior, and excessive sunlight exposure [42].

The etiology of cancer is a multi-step process in which several (between 4-7) distinct genetic events must occur for the initiation and development of disease to begin. A carcinogen, such as exposure to an environmental contaminant, can cause one or more of these genetic changes. However, this may or may not complete the necessary genetic events that must occur for cancer to fully develop. For example, the action of carcinogens is such that an initiating agent must first enter a cell in the body and act on the DNA (deoxyribonucleic acid) of that cell creating a mutation in the cell. Following this mutation, a promoting agent must act on the mutated cell so that the cell begins to rapidly reproduce making copies of itself including the genetic mutation (proliferate). Sometimes a cell must experience several attacks from the same or different initiators before it will move to the mutation phase.

Picture of cells denoting Initiating agent --> Mutation --> Promoting agent --> Cell Proliferation.

Researchers have found that the timing for introduction of an initiator or a promoter is important in that if the promoter enters the cells first, before the initiating agent, no cancerous growth will occur. Similarly, if the initiator and promoter phases are complete, but the promoter agent is removed from the cells, only benign (non-cancerous) tumors will occur. In between the cell mutation and proliferation phase, damaged cells can repair themselves before they form into a cancerous tumor. However, this repair takes time and must be completed before another promoter acts on the cell. There are some known carcinogens, such as cigarette smoke, which contain both initiators and promoters that act on the cells simultaneously. In this case, cells have little opportunity to repair themselves before rapid and uncontrolled growth of cells begins. Following the initiation and promotion phases are the progression and conversion phases in which mutated cells progress and convert to tumor cells. At this point, tumor cells can produce cancer. There are two types of cancer at this stage of development: in situ (cancer cells that have not moved into the tissues) and invasive (cancer cells within the tissues) [41]. Invasive cancer is the type that is most often reported and analyzed.

In conclusion, the ability of hazardous waste contaminants to cause cancer is dependent on the types, amounts and nature of the chemicals present and their relationship to an exposed individual's cells. The degree of cancer hazard, as defined in a toxicological sense, is dependent on the concentration of a contaminant, the intensity and the duration of the exposure that a person receives, as well as individual physiology. These factors are important issues in the etiology of cancer. Environmental factors are often implicated as the primary or contributing cause of cancer, however very few have been proven to be the cause of cancer. In fact only 1% to 4% of all cancer mortality can be attributed to environmental factors or pollution, while approximately 75% can be accounted for by personal behavior or lifestyle choices [41]. Current scientific research does not provide an absolute means of separating the effects of factors such as: heredity, gender, hormonal influences, natural occurring carcinogens in plants and animals, synthetic carcinogens, sexual habits and reproductive systems, personal lifestyle, and a whole host of other factors associated with human cancers; from each other in order to pinpoint one cause of cancer.

The American Cancer Society estimates that there were 1,220,100 new cases of invasive cancer in 2000 with an estimated 552,200 deaths. In New Hampshire it is estimated that there were 5,500 new cases and 2,500 deaths in 2000 [40]. It has been further estimated that there are approximately 8.4 million persons living in the United States today with some type of cancer. Nationally, the trends for both incidence and mortality are decreasing. In New Hampshire, the trends in cancer rates (i.e. the most common types) are comparable to those of the SEER rates, which are used by the American Cancer Society to estimate national cancer trends [38]. There were a total of 24,989 cases of cancer reported to the NHSCR over the years of 1993-1997 [38].

(4) Summary of Health Outcome Data Review

  1. A risk ratio analysis for all cancer types combined found there to be no statistically significant increased risk of cancer for the community in the census tracts around the Mohawk Tannery.

  2. For the city of Nashua as a whole, a Standard Morbidity Ratio analysis found that the rates of several types of cancer were slightly higher than expected, particularly for females in the sixth decade of life and older. The standard morbidity ratios that were statistically elevated fell within the low risk/weak association category (SMR range of 1.5 to 2.51).

(5) Recommendations

  1. DHHS will contact the Nashua Public Health Department regarding the results of this analysis. We will offer consultation regarding any potential surveillance activities and act as a clearinghouse for health education information to the citizens of Nashua.

  2. DHHS also recommends that the citizens of Nashua try to reduce their chances of developing cancer by following the main prevention guidelines issued by the American Cancer Society [40], which include:

    • Cessation of tobacco use.
    • Reduction of excessive alcohol use.
    • Limited or protected exposure to sunlight.
    • Increasing physical activities.
    • Practicing good nutritional habits.
    • Preventing infection from sexually transmitted diseases.
    • Self-examinations for cancers of the breast and skin.
    • A cancer-related checkup every three years for people between the ages of 20-40 and every year for people age 40 and older. This checkup should include examinations for cancers of the thyroid, oral cavity, skin, lymph nodes, testes and ovaries. Other types of cancer (breast, colon, rectum, prostate and uterus) have specific guidelines for routine screenings, which can be requested by any health care professional.

For more information on the cancers or prevention recommendations discussed in this section please contact the following organizations:

National Cancer Institute
http://cancernet.nci.nih.gov

American Cancer Society
http://www2.cancer.org/crcGateway/index.cfm
1-800-ACS-2345

Centers of Disease Control and Prevention
Division of Cancer Prevention and Control
http://www.cdc.gov/cancer
1-888-842-6355

(C) Community Health Concerns

When performing any public health assessment, DHHS gathers health concerns from people living in the vicinity of the site. The health concerns that people express are then used to direct the focus of the public health assessment so that questions from the community are answered. At the Mohawk Tannery, DHHS accomplished this task through three activities:

  • On February 8, 2001, DHHS mailed an educational needs assessment survey to the residents in the community near the Mohawk Tannery site.
  • On February 21, 2001, DHHS held a public availability session at the Amherst Street Elementary School in Nashua. Residents of the community were provided an opportunity to meet with DHHS staff, in a confidential setting, to discuss their health concerns and questions regarding the Mohawk Tannery. The public availability session was held at the end of a public meeting hosted by EPA and DES.
  • On May 2, 2001, DHHS held a public meeting at the Amherst Street Elementary School to present the findings of the draft public health assessment and to solicit written comments and questions from members of the community.

Based on responses from the written survey and the availability session, the key findings of the community outreach program were:

  1. A larger percentage of residents are interested in the Mohawk Tannery site than was previously thought.
  2. Currently, most residents receive site information through newspapers, mail, and the local cable station.
  3. Most residents would prefer to receive site information through the mail and the local newspaper.
  4. Nearly all of the survey respondents expressed a desire for information on contaminants found on-site, health effects and the routes of exposure.
  5. Half of the respondents indicated that they smell odors coming from the site.
  6. Almost half of the respondents indicated that they walk on an adjacent property, while one quarter indicated that they walk on the Mohawk Tannery property itself.
  7. Slightly over ¾ of respondents are "very interested" in the site.
  8. Almost two-thirds of the respondents have lived in their homes over 10 years.
  9. Few families have young children under the age of six.
  10. Over one quarter of respondents indicated that they would like their family physician to receive information about the site and the health effects of the chemicals that exist there.
  11. Respondents were mainly concerned with:
    • The health effects of exposure to site contaminants for themselves, their families, and their pets;
    • Extent of the contamination.
    • Whether or not they have been exposed to site contaminants.
    • The association between "odors" and "exposure to chemicals".
    • Current activities regarding site clean up.

A public health assessment contains information on: (1) the site contaminants and possible exposure routes; (2) the extent of contamination; and (3) the adverse health effects that have been associated with exposures to the types of chemicals present.

The following is a list of questions from the written survey and availability session on other topics not already addressed in the document. Since residents' health concerns shared in either the survey or availability session are considered confidential, all comments have been paraphrased to protect the identity of the respondent.

Please see Appendix D for more information on DHHS' outreach activities in the community near the Mohawk Tannery site.

(1) List of Other Health Concerns or Questions

  1. Can exposure to the chemicals on the site cause cancer, specifically pancreatic cancer?

No. While several of the contaminants are known or suspected carcinogens, exposures to these chemicals at the site are not expected to result in increased cancer risk.

The etiology (i.e., the cause) of pancreatic cancer is unknown. It ranks 11th among all cancers diagnosed in the United States with approximately 28,300 new cases expected in 2000 [45, 40]. The median age at diagnosis is 70 years with cases occurring most frequently in males [45].

The main risk factor that has been established for pancreatic cancer is cigarette smoking, with a two-fold risk for smokers as compared to non-smokers [45]. Epidemiological studies on other risk factors associated with pancreatic cancer have been inconsistent but have found that high fat intake, excessive consumption of coffee (more than 5 cups a day) and some alcoholic beverages, a medical history of diabetes, pancreatitis, and cholecystectomy are also related to an increased risk of developing this disease [44].

  1. Can exposure to the chemicals on the site cause or worsen respiratory illness, specifically asthma and sinus problems?

Exposures to odor-causing chemicals in the air currently or in the past are not expected to cause long-term adverse health effects, such as asthma. However, sensitive individuals with pre-existing respiratory illnesses may have experienced short-term coughing, wheezing, and eye-nose-throat irritation in the past when the odors were very strong. Asthmatics are anticipated to be more sensitive to hydrogen sulfide exposures than the general population [27].

Experts now believe that the vast majority of asthma prevalence is considered atopic (due to an allergen), but that not all patients undergoing a diagnostic test show a positive response to specific allergens. The most common indoor allergens are: dust mites; pet dander, saliva or urine; cockroach or rodent antigens; fungi and molds. Outdoor allergens are most often pollen and molds. Risk factors that have been associated with asthma in adults are thought to be exercise-induced asthma, stress-induced asthma, changes in air temperature, and occupational sensitizers. Occupational exposure to both inorganic and organic chemicals in adults has been documented as a cause for asthma exacerbation [46]. However, the exposure levels of these occupational sensitizing agents are very high when compared to those that the average adult would experience in every day life. Environmental exposure to particulates and gases in the air such as sulfur dioxide, ozone, nitrogen dioxides, and acidic aerosols as well as direct cigarette smoke have been shown to exacerbate symptoms of asthma, however they have not been proven to cause the development of the disease. Passive cigarette smoke, commonly known as "secondhand smoke", as experienced by young children, has been established as a trigger that increases the risk of asthma and asthma exacerbations.[46]

  1. Could children who lived in the area while the tannery was in operation experience problems later in life?

Unlikely. Exposures to contaminants onsite may have been higher in the past while the tannery was operating but trespassing would also have been less likely because the site would have been occupied (not abandoned as it is today). Exposures to odor-causing compounds are not likely to cause any long-term, serious, adverse health effects.

  1. How is the health of former employees of the tannery affected?

This is uncertain. We do not know what these workers might have been exposed to. Anyone who worked at the facility who is concerned about their health should consult with their physician. DHHS can provide toxicological information to physicians as needed.

  1. What precautions should we be taking?

People should stay off the site.

  1. Can exposure to site contaminants cause skin rashes, headaches, loss of hair?

While these issues are important, they are considered symptoms of many conditions and not specific diseases in themselves. Therefore, the effect of site contaminants cannot be separated from other causes of these general symptoms.

  1. The neighbors said that the tannery used to haul the hides down the street in trucks. Water would drip out of the trucks onto the road. This water would be washed onto people's lawns. Is this a problem? Would this contaminate the neighbor's yards?

No. Trucks hauling hides through the community were either hauling (1) untreated hides to the tannery from the slaughterhouse or (2) finished leather from the tannery to customers. Untreated hides were preserved in salt or brine solutions. Finished leather was dry [21]. Therefore, any water dripping from the trucks was probably only a non-toxic salt solution.

  1. When actual cleanup begins, will we be subjected to any dangers? For instance, by walking on the site, walking downstream, or by boating on the river?

Before the cleanup begins, EPA will devise a detailed remedial plan which will include measures to ensure the safety of the neighboring residents. EPA will hold a public meeting to discuss this plan before the work begins.

  1. Can animals who enter the site bring home contamination and be a danger to us?

This is extremely unlikely. Most of the contaminated sludge on the site is covered by several feet of soil.

  1. Can private wells be tested for contamination?

Yes. If you live near the site and have a private well for your drinking water source, we recommend that you contact the Waste Management Division of the Department of Environmental Services (271-3503). Depending on how close you are to the site, DES may agree to test your well.

  1. Are there any short-term health effects that could occur following exposure to site contaminants?

Neither short-term nor long-term health effects are expected from current exposures. In the past when odors were very bad, some residents may have experienced short-term nausea, headaches, cough, wheezing, and eye-nose-throat irritation.



1. A nanogram is one billionth of a gram. Therefore, nanograms per kilogram is equivalent to parts per trillion.
2. The 1986 study only listed the concentration for each congener group (e.g., hexachlorinated dibenzodioxins), not individual congeners. To calculate the TEQ for these samples, we have assumed that only "2,3,7,8" isomers were present, which represents the maximum possible toxicity of the sample. Because of the uncertainty created by this assumption, Table 1 only lists the results of the dioxin tests in 2000, when individual dioxin congeners were measured.
3. A picogram is 1/1,000,000,000,000 of a gram.
4. The Minimum Risk Level for 2,3,7,8-TCDD divided by the Toxic Equivalency Factor for the 2,3,7,8-TCDF congener.


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