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1. ATSDR > Public Health Assessments & Consultations

PUBLIC HEALTH ASSESSMENT
NEW HAMPSHIRE PLATING COMPANY

MERRIMACK, HILLSBOROUGH COUNTY, NEW HAMPSHIRE

ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The tables in this section list the contaminants of concern. The contaminants are evaluated in subsequent sections of this public health assessment, and it is determined whether exposure to them has public health significance. ATSDR selects and discusses contaminants using the following factors:

• concentrations of contaminants on and off the site;



• field data quality, laboratory data quality, and sample design;



• comparison of on- and off-site concentrations with comparison values for ⁽¹⁾ non-carcinogenic endpoints and ⁽²⁾ carcinogenic endpoints and;



• community health concerns.

In the data tables in the On-site and Off-site Contamination subsections, the fact that a contaminant is listed does not mean that it will cause illness or injury if exposures occur. Instead, the list specifies contaminants that will be further evaluated in the public health assessment.

The data tables include the following abbreviations:

CREG = Cancer Risk Evaluation Guide

EMEG = ATSDR Environmental Media Evaluation Guide

MCLG = EPA Maximum Contaminant Level Goal

MCL = EPA Maximum Contaminant Level

ppm = parts per million

ppb = parts per billion

RfD = EPA Reference Dose

RfC = EPA Reference Concentration

RMEG = Reference Dose Media Evaluation Guide

AHA = American Heart Association

ATSDR health assessment comparison values are contaminant concentrations in specific media used to select contaminants for further evaluation. Those values include environmental media evaluation guides (EMEGs), cancer risk evaluation guides (CREGs), reference dose media evaluation guides (RMEGs) and other relevant guidelines.

EMEGs are media-specific comparison values that are used to select contaminants of concern at hazardous waste sites. EMEGs are derived from the Minimal Risk Levels (MRLs) presented in the ATSDR Toxicological Profiles. An MRL is an estimate of daily human exposure to a chemical that is likely to be without a substantial risk of harmful (noncancerous) effects over a specified duration of exposure. EPA's reference dose (RfD) and reference concentration (RfC) are estimates of the daily exposure to a contaminant unlikely to cause illness or injury. RMEGs are media-specific comparison values that are used when EMEGs are not available. RMEGs are derived from RfDs.

CREGs are estimated contaminant concentrations based on the incidence of one excess cancer in a million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slope factors. EPA's maximum contaminant level goal (MCLG) is a drinking water health goal. Maximum contaminant levels (MCLs) are contaminant concentrations in water that EPA deems protective of public health (considering the availability and economics of water treatment technology) over a lifetime (70 years) at an ingestion exposure rate of 2 liters of water per day. MCLs are regulatory concentrations; MCLGs are not.

A. On-site Contamination

Between 1981 and 1991, various samples from on-site environmental media were analyzed. The collection and analyses of the samples were initiated by NHPC, NHDES, or EPA.

For purposes of this public health assessment, on site is considered within the site perimeter fence.

Waste Material-Lagoon Surface Water and Effluent (wastewater)

Between September 1981 and July 1986, 41 samples of lagoon water and 28 samples of effluent were analyzed. Between September 1983 and October 1984, samples of effluent from the NHPC operation, which discharged into the NHPC lagoon, and surface waters of the Lagoon #1 were collected monthly and analyzed for cyanide. Most of the other samples collected from those media were analyzed for volatile organic compounds (VOC) and for selected inorganic compounds ⁽¹⁾. The maximum contaminant concentrations for the on-site lagoon surface water and effluent are shown in Table 1. The data reflect contaminant levels before lagoon remediation (i.e., removal) began.

Table 1. Maximum Contaminant Concentration in On-site Waste
Materials-Lagoon Surface Water and Effluent Water

a- EMEG and RMEG comparison values reported for children.
b- Value for chromium +6 obtained from one sample of effluent--corresponding total chromium value was reported at 9.8 ppb.
NA- Not Available.

Waste Material-Lagoon Sludge

Between 1981 and early 1989, about 24 samples of lagoon sludge were obtained and analyzed primarily for selected heavy metals and cyanide. The most comprehensive sampling of the extent of contamination in the lagoon area was performed by EPA in October 1989. One objective of that sampling was to determine the vertical and lateral extent of contamination in the four on-site lagoons. A total of 163 sludge samples, at depths ranging from 0-12 feet, were obtained in a grid fashion from the four lagoons ⁽¹²⁾. The 0-foot samples were obtained within the first three inches of sludge ⁽¹³⁾. Of the 163 samples, 117 were analyzed for selected heavy metals (i.e., cadmium, chromium, lead, nickel, and zinc); 34 samples were analyzed for selected heavy metals and cyanide; and 12 samples were analyzed for cyanide only ⁽¹²⁾. On January 21, 1991, EPA collected five grab samples of lagoon sludge to determine concentrations of chromium (VI) in relation to total chromium concentrations. The results of that limited sampling indicate that most of the chromium in the lagoon sludge at the time of sampling was in the less toxic form (i.e., Cr (III)). The maximum contaminant concentrations in on-site lagoon sludge are shown in Table 2. Those data reflect contaminant levels before lagoon remediation (i.e., removal) began.

Soil

In May 1987, five soil samples were obtained from beneath the NHPC facility building. The composite samples were obtained at a maximum depth of 18 inches ⁽²⁾. In addition, during the comprehensive sampling of the lagoon sludge, which was performed by EPA in October 1989, some 34 samples were collected to determine the extent of contamination in the soil adjacent to the lagoons, and as part of an ecological study ^(11,12). Samples were collected at depths ranging from 0-12 feet. Surface soil samples were collected at a depth of 0-3 inches ⁽¹³⁾. The 1987 soil samples were analyzed for selected heavy metals and cyanide. Of the 34 samples collected in October 1989, 27 were analyzed for selected heavy metals, four for the same heavy metals and cyanide, and three for cyanide only ⁽¹²⁾.

Table 2. Maximum Contaminant Concentrations of Waste Material-Lagoon Sludge

a- EMEG and RMEG comparison values reported for children.
b- Depth of sample containing maximum concentration not known.
c- Surface sludge sample obtained from a depth of 0 - 3 inches.
d- RMEG for chromium (VI).
e- RMEG for chromium (III).
f- RMEG for copper cyanide.
g- RMEG for nickel.
NA- Not Available.

During April and May 1990, EPA investigated the extent and degree of soil contamination by VOCs and heavy metals at the site. The NHPC site (excluding lagoons) was partitioned into three plots of land, on which a 50-foot-square grid system was established. Soil samples (156) were collected by removing 2-4 inches of soil; the samples were screened on site for heavy metals. Soil samples (173) were collected at a depth of 2-2.5 feet and screened on site for VOCs. Thirty-two duplicate soil samples were collected and sent to the EPA laboratory for VOC analysis; 17 duplicate soil samples were sent to the EPA laboratory for heavy metal analysis. Three of the soil samples were also analyzed for cyanide ⁽¹⁴⁾. The maximum on-site surface soil contaminant concentrations are summarized in Table 3. Those values are for contaminant concentrations in soil that have not been remediated and remain on site.

Table 3. Maximum Contaminant Concentrations in On-site Surface Soil Samples
(0-3 inches)

a- EMEG and RMEG comparison values reported for children.
b- Value represents an on-site screening concentration only-- sample was not sent to laboratory for confirmation.
c- RMEG for chromium +6.
d- RMEG for chromium +3.

Building Interior Contamination

On February 2, 1990, EPA collected four interior building samples from the NHPC facility. Three samples were taken from the laboratory, main shop, and the line and zinc room by sweeping dusts and other small particles; one sample was taken from the office vacuum cleaner. The samples were analyzed by X-ray fluorescence for selected heavy metals (total chromium, lead, nickel, zinc, cadmium, and tin) ⁽¹⁵⁾. In addition, on May 4, 1990, EPA entered the NHPC building. Ambient air throughout the building was screened for VOCs and combustible gases--no VOCs were detected above background, and oxygen levels were in the normal range.

Soil samples were taken from a trench in the NHPC building. Four soil samples were collected and screened for VOCs; three soil samples were collected and screened for heavy metals; and one duplicate sample was collected and sent to the EPA laboratory for VOC and heavy metal analysis. In addition, four bulk asbestos samples were taken--two from an air-cell-type pipe insulation and two from ceiling tiles. Asbestos was found at a maximum 30 % in one pipe insulation sample--the type of asbestos found was chrysotile. Asbestos was not found in two ceiling tile samples ⁽¹⁴⁾. The maximum contaminant concentrations in the NHPC building were detected in samples of dust and other small particles--those data are summarized in Table 4.

Table 4. Maximum Contaminant Concentrations in NHPC Building
Interior

a- EMEG and RMEG comparison values reported for an adult.
b- RMEG for chromium +6.
c- RMEG for chromium +3.
NA- Not Available.

On-Site Groundwater - Monitoring Wells

Between 1981 and 1990, groundwater quality has been investigated on numerous occasions. During that period, about 20 on-site overburden (shallow) aquifer monitoring wells were installed and sampled. In addition, two on-site bedrock monitoring wells were installed and sampled. Sampling of those wells was initiated by NHPC, NHDES, and EPA. In June 1990, 13 on-site monitoring wells were analyzed for total cyanide, dissolved metals (filtered samples), and VOCs; some were also analyzed for base neutral and acid extractable compounds (i.e., semi-volatile organic compounds)⁽¹⁶⁾. Most of the samples collected before June 1990 were analyzed for VOCs, heavy metals, and total cyanide--those samples were not filtered before analysis. Groundwater samples from on-site bedrock monitoring wells were not analyzed for heavy metals. Samples collected in December, 1993 as part of the RI/FS were analyzed for VOCs, total metals and cyanide. Five metals and eight VOCs were detected at levels above their respective MCLs.

The maximum contaminant concentrations detected in on-site groundwater samples were from the overburden aquifer (Table 5). Some of the maximum inorganic contaminant concentrations reported in Table 5 were detected in unfiltered samples. Several contaminants of concern were also detected in samples of water from the bedrock aquifer. Trichloroethene (115 ppb) was the only VOC detected at levels above comparison values in samples of on-site bedrock aquifer groundwater (Table 5). Cyanide and 1,1,1-trichloroethane were detected, but were not above comparison values.

Table 5. Maximum Contaminant Concentrations in On-site
Groundwater Monitoring Wells

a- EMEG and RMEG values reported for children.
b- RMEG for chromium (VI)
c- RMEG for chromium (III)
d- EPA Action Level
e- RMEG for free cyanide
NA- Not Available

On-Site Ambient Air

During the excavation and treatment of soils and sludge material performed by EPA from June to November 1990, ambient air samples were collected. A system of 11 on-site and five off-site (perimeter) monitoring stations was designed. On any given day, only part of the monitoring system would operate, depending on the location of on-site activities and wind direction. Real-time measurements were also obtained on-site to measure organic vapors and hydrogen cyanide generation. No detectable concentrations of organic vapors or hydrogen cyanide were measured. One of the off-site monitoring stations is located directly behind the nearby child daycare center. The monitoring devices at those stations sampled for cadmium, chromium, and cyanide dusts. Conditions during collection of most samples were hot (greater than 80 ^oF)and dry⁽¹⁸⁾. Such conditions probably are a worst-case scenario for generation of VOCs and dusts (particulates). A summary of the contaminant concentration ranges for on-site ambient air is shown in Table 6.

Table 6. Range of Contaminant Concentrations in On-site Air Samples

a- CREG reported for chromium (VI).
ND- Not Detected.
NA- Not Available.

B. Off-site Contamination

Off-Site Surface Water

Between 1982 and 1990, NHDES collected 24 surface water samples from Horseshoe Pond, which were analyzed for VOCs, selected heavy metals, and cyanide ^(1,18). The 1982 samples from Horseshoe Pond contained the three highest concentrations of cyanide found in any sample of water from Horseshoe Pond (i.e., 50, 160, and 580 ppb). One 1982 pond sample contained cadmium at 2 ppb. A more recent analyses of water from Horseshoe Pond carried out under the RI/FS in July of 1993 yielded non-detect results for cyanide, VOCs and metals including cadmium ⁽¹⁸⁾.

Between 1986 and 1988, NHDES collected five water samples from the Merrimack River upstream from, adjacent to, and downstream of the site. Those samples also were analyzed for VOCs, selected heavy metals and cyanide. One sample from the Merrimack River taken prior to the RI/FS showed cyanide at a concentration of 12 ppb ⁽¹⁾. Sampling of Merrimack river surface water during the RI/FS detected no cyanide, VOCs or metals. Contaminant concentrations in off-site surface water are summarized in Table 7.

Table 7. Range of Contaminant Concentrations in Off-Site Surface Water

a-Maximum concentrations reported were detected in 1982
samples from Horseshoe Pond
b- EMEG and RMEG values reported for children
c- RMEG for chromium +6
d- RMEG for chromium +3
e- RMEG for free cyanide
NR- Not Relevant
ND- Not Detected

Off-Site Sediment

During February 1991, EPA collected ten grab samples of sediment from the Merrimack River. The samples were taken upstream from, adjacent to, and downstream of the site. The samples were analyzed for cadmium, total chromium, chromium +6, and total cyanide ⁽¹⁹⁾. Sediment sampling of Horseshoe Pond was conducted in July of 1993 as part of the RI/FS. Sediment samples were taken in a radial pattern around the pond and analyzed for metals, cyanide, VOCs and semi-volatile organic chemicals (SVOCs)⁽⁴²⁾. Contaminant concentrations in off-site sediment from the Merrimack River and Horseshoe Pond are summarized in Table 8.

Table 8.Range of Contaminant Concentrations in Off-Site Sediment

a- EMEG and RMEG comparison values reported for children.
b- EMEG for chromium +3
c- RMEG for copper cyanide
d- PAH detected in single Horseshoe Pond sediment sample(HP-07)
ND- Not Detected
NA- Not Available

Off-Site Soil

During on-site sampling by EPA in 1990, three samples of off-site soil were collected adjacent to Wright Avenue across the street from NHPC (i.e., the YMCA property). Those off-site samples were obtained and screened in the same manner as on-site soil samples. One duplicate sample was sent to the EPA laboratory for heavy metal analysis and confirmation. Heavy metals were not detected above background levels in any of the three off-site samples.

Off-Site Ambient Air

See the discussion concerning on-site ambient air for details of off-site air sampling performed at the site. During the June through August 1990 excavation period, cyanide was detected eight times at off-site monitoring stations. Cyanide was detected three times at the day care center monitoring station; the maximum cyanide value detected was 0.026 mg/m³--this was the maximum value detected off-site. Cadmium was detected in only one on- or off-site sample--the day care center ⁽¹⁷⁾. Contaminant concentration ranges for off-site ambient air are summarized in Table 9.

Table 9.Range of Contaminant Concentrations in Off-site Air Samples

a- CREG reported for chromium +6.
BD- Not Detected.
NA- Not Available.

Off-Site Groundwater - Monitoring Wells

Between 1981 and 1990, groundwater quality near the site had been investigated on numerous occasions. During that period, 36 off-site surficial aquifer monitoring wells were installed and sampled. In addition, three off-site bedrock monitoring wells were installed and sampled. One bedrock production well, used by Jones Chemical Inc. as a source of industrial cooling water, was also sampled. Off-site sampling of the monitoring wells was initiated by NHPC, NHDES, EPA, and several commercial entities that abut the NHPC property. In June of 1990, 32 samples from off-site monitoring wells were analyzed for total cyanide, dissolved metals (filtered samples), and VOCs. Some were also analyzed for base neutral and acid extractable compounds (i.e., semi-volatile organic compounds) ⁽¹⁶⁾. Most of the samples collected before June 1990 were analyzed for VOCs, heavy metals, and total cyanide. Further sampling was carried out in December, 1993 as part of the RI/FS. The maximum contaminant concentrations detected in off-site groundwater were from samples taken from the overburden aquifer--those concentrations are shown in Table 10.

Several VOCs were detected above their comparison values in groundwater samples from off-site bedrock monitoring wells (Table 10). The VOCs detected included chloroform (8 ppb), 1,2-dichloroethene (2 ppb), and trichloroethene (115 ppb) ⁽¹⁾. The 1,2-dichloroethene and the trichloroethene were detected in water samples from the Jones Chemical Production well. Several heavy metals and cyanide were detected at concentrations below their respective comparison values in groundwater samples drawn from the bedrock aquifer.

Off-Site Public and Private Water Supply Wells

In March 1990, samples from a private drinking water well and the Jones Chemical production well, both on Daniel Webster Highway, were analyzed for VOCs. The private well was resampled in August of 1993 ⁽⁴³⁾. Two nearby MVWD municipal water supply wells are monitored monthly for lead and copper and annually for VOCs, radon, and other priority compounds ⁽²⁰⁾. No contaminants were detected in samples from these two off-site municipal wells.

Maximum contaminant concentrations detected in the two samples taken from the off-site private well are summarized in Table 11. VOC contamination was also detected in the Jones Chemical supply well but is not included in the table below since this well is not used for domestic purposes. No contaminants detected in the Jones Chemical production well exceeded their respective MCLs.

Table 10. Maximum Contaminant Concentrations in Off-site
Groundwater Monitoring Wells

a- EMEG and RMEG comparison values reported for children.
b- RfD for chromium (VI).
c- RfD for chromium (III).
d- EMEG for free cyanide.
NA- Not available.

a- Maximum concentrations reported for two samples from the off-site private drinking water well on Daniel Webster Highway.

C. Toxic Release Inventory Data

To identify facilities that could contribute to the air, surface water, and soil contamination near the NHPC site, ATSDR searched the 1987, 1988, and 1989 Toxic Release Inventory (TRI). TRI is a database developed by EPA from chemical release (air, water, and soil) information provided by certain industries. In this case, TRI contained information about air releases in the Merrimack area and in the zip code in which the site is located. However, because these releases were from facilities at least one mile from the site, and the most significant release was from a facility at least two miles from the site, it is not likely that those contaminants affected air quality in the vicinity of the NHPC site ⁽²¹⁾.

D. Quality Assurance and Quality Control

Data on quality assurance/quality control (QA/QC) techniques used during preparation of this public health assessment were not available for review. It is believed, however, that most of the data in this assessment were produced by qualified laboratories contracted by NHDES or EPA. Furthermore, all of the samples collected or analyzed by the NHDES or EPA contractors have passed strict QA/QC requirements.

E. Physical and Other Hazards

No physical hazards were apparent at the site. Any remaining equipment or other hazards in the NHPC building are well secured.

PATHWAYS ANALYSES

To determine whether nearby residents are exposed to on-site contaminants or to those migrating from a site, ATSDR evaluates the environmental and human components that lead to human exposure. This pathways analysis consists of five elements: source of contamination; transport through an environmental medium; a point of exposure; a route of exposure, and an exposure population. The first three elements pertain to environmental pathways,--the two remaining elements pertain to human exposure pathways.

ATSDR categorizes exposure pathways as either completed or potential. For a completed pathway to exist, five elements must be present and there must be evidence that exposure to a contaminant has occurred, is occurring, or will occur. A pathway is potential when at least one of the five elements is missing, but could exist. Potential pathways indicate that exposure to a contaminant could have occurred, could be occurring, or could occur in the future. An exposure pathway is eliminated if at least one of the five elements is missing and will never be present. Table 12 identifies the completed exposure pathways at NHPC; Table 13 identifies the site's potential exposure pathways. The discussion following the two tables address only pathways important and relevant to the site. Also discussed are some of the eliminated pathways and those about which there is community concern.

TABLE 12. COMPLETED EXPOSURE PATHWAYS

( ) - Estimated exposed population.

TABLE 13. POTENTIAL EXPOSURE PATHWAYS

A. Completed Exposure Pathways

NHPC Waste Material Pathway

Since children played on-site before site restrictions were in place, they were probably exposed to on-site waste material. Waste materials included lagoon sludge, soils, and surface water. The greatest exposure to contaminants was from the waste materials in the lagoon system, although soils at other on-site locations also were probable points of exposure. It is likely that exposure to lagoon sludge contaminants varied depending on the dryness of the sludges (Table 12).

The lagoon system, soils near the lagoon, and the undefined wetlands are contaminated primarily because of the discharge of effluent to the lagoon system. When the lagoon system overflowed, that discharge contaminated the near lagoon soils and the undefined wetlands. Contamination of other on-site soils probably resulted from other disposal methods or from leaks from pipes or storage tanks. The results of the extensive characterization of on-site soils near the perimeter of the site and the lack of a mechanism for transport of contaminants to off-site soils indicate that most, if not all, of the soil contamination is confined to on-site areas.

Soil ingestion is an important route of exposure for children who played on-site, particularly for children younger than 6 years ⁽²²⁾. Soil ingestion typically is greater for young children because of their greater hand/mouth activity. Because the ages of the children who played on site are not known, however, it is difficult to determine the amount of soil they might have incidentally ingested. Furthermore, given the climatic conditions of New Hampshire, it is likely that cold weather and snow precluded recreational activities and contact with contaminated media at the site during part of the years that children probably were exposed. Children could have been exposed to contaminants at the site from the early 1960s until 1987-1989, when the lagoon fence was erected and remedial actions began. The number of children who played on site and how often they played there are not known. Given current conditions at the site, it is highly improbable that children now have appreciable exposure.

As shown in Tables 2 and 3, on-site surface sludge and soils have been contaminated with high levels of heavy metals and cyanide. In addition, high levels of VOCs and heavy metals were found in the NHPC effluent and in surface water in the lagoons (Table 1). EPA has remediated the most significant contaminant concentrations in the lagoon system (Table 2). The contaminant concentrations shown in Table 3 remain on site.

Ambient Air Pathway

Children who attended the Former Avanti Day Care Center that abuts the NHPC site possibly were exposed in the past to contaminated ambient air during site remediation activities that occurred during summer, 1990 (Table 12). According to ambient air monitoring data at an off-site sampling location behind the day care center, however, contaminants were detected only four times during this time period. Cyanide was detected three times at a maximum value of 0.026 mg/m³; cadmium was detected once at a concentration of 0.0003 mg/m³. Those concentrations probably reflect a worst-case scenario of off-site dust generation at the site because they were detected during remedial activity (i.e., when soils are disturbed) and during hot and dry conditions. When remediation was not taking place on site, the lagoons were usually wet because of discharge from the NHPC site and because they are natural water discharge areas. Localized dust generation during dry periods was reported when remedial workers walked on the dried lagoon sludge. There were no reports, however, of dust bowl-like conditions at the site.

NHPC Building Pathway

Former workers at the NHPC facility were probably exposed to high concentrations of heavy metals (Table 4) through ingestion of dusts and other small particles on work surfaces in the building (Table 12). The number of employees who worked at the site during its years of operation is not known. No future exposure pathways exist as the building was demolished in December of 1994.

Private Well Pathway

Contaminated water from one private well, located one-half mile southwest of the site represents possible past, current, and future exposure pathways (Table 12). That well is believed to be drawing water from the overburden aquifer. Since most, if not all, of the contaminated overburden groundwater is being discharged to the Merrimack River and Horseshoe Pond, it is not likely that contamination of the private well is related to the NHPC site. Therefore, it is likely that another unknown source of contamination exists and is contributing to the contamination of this well. No private wells used for domestic purposes or public water wells are believed to exist in the area of overburden groundwater contamination.

Since the contaminated private well is believed to supply a multiplex dwelling (presumably four residential units), ATSDR estimates that approximately 12 persons were exposed to several volatile organic chemicals (VOCs) by ingestion, inhalation, and skin contact. Since those contaminants evaporate into the air from water during showers or baths, people are exposed as they breathe the air in their homes. In addition, the contaminants are absorbed through the skin during showers and/or baths, increasing exposure ⁽²³⁾. Although the source of the private well contamination is not known, and only two water samples from the well have been analyzed, it is impossible to determine the duration and actual concentrations of exposure over time. Hence, additional sampling and analyses of water from the private well are needed to completely characterize this pathway.

B. Potential Exposure Pathways

NHPC Waste Material Pathway

Because children played on site before site restrictions were in place, it is possible that children breathed VOCs and soil dusts containing heavy metals and cyanide (Table 13). The source of the VOCs was the effluent and surface water in the lagoons; the soil dusts were from the lagoon sludge, near-lagoon soils, and other on-site areas with soil contamination. The primary points of exposure were the waste materials in the lagoon system and other on-site areas with soil contamination. Table 12 and the Completed Exposure Pathways section provide additional details on the exposure of children who once played on site.

No ambient air data for VOCs and soil dust are available to characterize the concentrations to which the children might have been exposed. Because this pathway relates, in part, to localized ambient air contamination in the past, sometimes caused by the use of all-terrain vehicles (ATVs) on site, those data will never be available. Given the high concentrations of heavy metals and VOCs in the on-site soils, sludge, effluent, and surface water (Tables 1-3), however, it is reasonable to assume that the ambient air pathway contributed to the total exposure of children who once played on site.

Private Well Pathway

The results of groundwater monitoring in the overburden and bedrock aquifers indicate that on- and off-site groundwater is contaminated with VOCs, heavy metals, and cyanide. Contaminated groundwater in the overburden aquifer has migrated from on-site source areas south, east, and southeast. The direction of contaminant migration is consistent with groundwater hydrology in the site area. The direction of contaminant migration in the fractured bedrock aquifer is not known. The bedrock aquifer monitoring network consists of two on-site and four off-site wells. Because the fractured bedrock is expected to influence groundwater flow in the bedrock aquifer, the localized movement of contaminants in groundwater cannot be characterized ⁽¹⁾. Since the bedrock and overburden aquifers intercept to form one aquifer system, however, it is likely that some contaminated groundwater moves in the same direction as groundwater in the overburden aquifer ⁽¹⁾. Hence, it is possible that contaminated bedrock groundwater has moved toward and under the Merrimack River; it is not known if the bedrock aquifer discharges to the river.

There are 43 private wells across the river in Litchfield, New Hampshire that are within a half-mile radius of the site. These wells represent potential points of exposure to contaminated groundwater, particularly if they are bedrock wells (Table 13). The current bedrock monitoring network does not, however, allow for characterizing that pathway. The Draft RI/FS has not adequately addressed this issue. It is unlikely that the two Litchfield public water wells, which are operated by the SNHWC, could become contaminated because they are about 3-4 miles from the site, and they do not draw water from the bedrock aquifer.

Groundwater contamination has been detected in monitoring wells on the YMCA property. A future potential exposure pathway exists for this property relative to the installation and use of drinking water wells.

Merrimack River Pathway

Surface Water and Sediment

The results of groundwater monitoring and hydrogeologic investigations indicate that groundwater contaminated with VOCs, cyanide, and possibly heavy metals, has migrated from on-site contaminant source areas to off-site areas east and southeast of the site. Some of those contaminants have probably discharged into the Merrimack River. To date, surface water and sediment monitoring data have not shown elevated levels of site-related contaminants, except cyanide in one surface water sample (12 ppb). Sampling of Merrimack River surface water conducted during the RI/FS yielded non-detect levels of VOCs, metals and cyanide. Sediment samples taken from the river during the RI/FS were non-detect for VOCs and within background ranges for metals.

Fish

Potential past, present, and future exposure to site contaminants that may bioaccumulate in fish is possible for individuals who have eaten or eat fish from the Merrimack River (Table 13). As indicated previously, however, the only contaminant detected at elevated levels in sediment and surface water samples from the Merrimack River was cyanide, at 12 ppb. Fish bioaccumulate very little cyanide into their bodies ⁽²⁴⁾. Cyanide was detected in surface water only once at low levels; it was not detected at all in sediment samples. Therefore, it is not likely that fish are bioaccumulating cyanide at levels of public health concern.

NHPC Workers Pathway

Former NHPC workers might have been exposed in the past by way of inhalation of heavy metal-contaminated particles in indoor air (Table 13).

Data exist estimating ingestion exposure to dusts and other small particles in the NHPC building. However, no known data exist on dust in air inside the building to determine potential workers' exposure while NHPC was operating. Complete analysis of the indoor air pathway is not possible because current indoor air conditions do not represent conditions when the facility was operating (i.e., when workers were exposed). Specifically, remedial actions in the building have probably reduced ambient air dust levels; it is likely that the highest levels of contaminated dusts in ambient air were generated when workers disturbed contaminated work surfaces. Furthermore, given the high concentrations of heavy metals on work surfaces, ambient air exposure could have been significant.

Horseshoe Pond Pathway

Surface Water and Sediment

Results of groundwater monitoring and hydrogeologic investigations indicate that groundwater containing VOCs, cyanide, and possibly heavy metals has migrated from on-site contaminant source areas to off-site areas south of the site. Contaminated groundwater probably discharges at the northern shore of the outer bank of Horseshoe Pond. People swim near residential areas about 500 feet across the lake from the discharge point (Figure 1).

Surface water samples obtained in 1982 showed elevated levels of cyanide (up to 580 ppb). Cadmium was detected in one sample at 2 ppb. Analyses of the most recent surface water samples taken during the RI/FS in July, 1993 did not detect VOCs, metals or cyanide above detection limits. Sediment sampling of Horseshoe Pond was conducted in July, 1993 as part of the RI/FS. Samples were taken in a radial pattern around the pond. Several metals were detected at concentrations similar to background levels. Arsenic detected in one sample at a slightly higher level than background (15.6 ppm) is thought to result from naturally occurring sources. No on-site source of arsenic has been identified.

Based on Horseshoe Pond sediment and surface water sampling, past, current and future exposures to contaminants in these media are expected to be minimal.

Fish

As indicated previously, the only contaminants detected at elevated levels in surface water samples from Horseshoe Pond were cyanide and cadmium. Fish bioaccumulate very little cyanide ⁽²⁴⁾. Since some fish species are bottom feeders, they are in close contact with sediment; therefore, the potential exists for fish to bioaccumulate site-related contaminants (e.g., cadmium) discharging into Horseshoe Pond.

This potential is estimated to be minimal based on recent sediment and surface water sampling. Sediment samples taken from Horseshoe Pond during the RI/FS were analyzed for several metals including arsenic, cadmium, chromium, copper, lead, nickel and zinc. Cadmium was not detected in any samples. Slight elevations in lead (HP-04) and arsenic (HP-06) concentrations were noted when compared to a representative background sample (HP-01). These increases are most likely due to background variability and do not represent a site related source. Lead and arsenic do not bioaccumulate in in the edible portion of fish and do not represent a hazard via this pathway.

It should be noted that NH DPHS has issued a health advisory for the ingestion of mercury in largemouth bass taken from Horseshoe Pond (see Appendix D-5). Mercury was not analyzed for in any sediment or surface water samples and is not thought to be a site related contaminant.

PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

This section discusses health outcome data, health effects in individuals exposed to particular contaminants, and specific community health concerns. To evaluate health effects, ATSDR has developed minimal risk levels (MRLs) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of a level of daily human exposure to a contaminant below which non cancerous adverse health effects are unlikely. MRLs are developed for each route of exposure (e.g., ingestion and inhalation) and for the length of exposure (e.g., acute, less than 14 days; intermediate, 15 - 364 days; and chronic, 365 days or more). Because ATSDR has no methodology to determine amounts of chemicals absorbed through the skin, the Agency does not have MRLs for skin exposure. ATSDR presents information on MRLs in its series of Toxicological Profiles on hazardous substances. These chemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status. The following discussion uses information obtained from the ATSDR Toxicological Profiles to identify health effects that might be related to site exposures.

Children Playing on the Site

ATSDR has determined that children playing on site were exposed to several contaminants (Table 14). Each contaminant is discussed by route of exposure. To estimate exposure dose, it was assumed that the children would ingest 200 milligrams (mg) of soil or sludge (dried), during an exposure period of 4 days. Exposures were estimated for 6-month periods. A surface water ingestion rate of 5 ml was used to estimate incidental ingestion of surface water by children playing in the lagoons.

Cadmium

Children were exposed to cadmium at the site through ingestion of NHPC surface water/effluent, NHPC waste material/lagoon sludge, and surface soil. Ingesting very high cadmium levels (0.07 mg/kg, estimated dose for children weighing 35 kg or approximately 77 pounds) severely irritates the stomach, leading to vomiting and diarrhea. Cadmium build up causes kidney damage in some people, and can lead to problems in calcium metabolism. As a result, bones become fragile and break easily. Skin contact with cadmium is not known to cause illness or injury in people or animals. The kidney is the main target organ of cadmium toxicity after extended oral exposure ⁽²⁷⁾. Human studies have shown that prolonged cadmuim exposure can lead to a high incidence of abnormal kidney function, indicated by protein in the urine and a decrease in kidney function. Kidney abnormalities may increase in severity even after exposure has ended. Growing children are particularly sensitive to cadmium exposure.

As shown in Table 14 (at the end of this section), children were exposed to cadmium in dried sludge, and their estimated exposure dose exceeded the chronic MRL of 0.0002 mg/kg/day for cadmium ingestion. The estimated dose suggests that there is a possibility of mild kidney damage, indluding proteinuria, to occur. Proteinuria is the presence of increased protein in the urine. The estimated exposure dose for cadmium in the surface water and soil was below the chronic MRL for ingestion. However, that dose exceeds the emetic dose of 0.07 mg/kg/day and may lead to vomiting in some cases. No severe illness or injury would be expected. No evidence exists that people or animals exposed orally to cadmium have an increased incidence of cancer.

Chromium

Chromium, a naturally occurring element found in animals, plants, rocks, and soil and in volcanic dust and gases, was found in surface water, sludge, and soil on site. Chromium exists in three forms: chromium (II), chromium (III), and chromium (IV) Chromium (III) compounds are stable and are found in aerobic environments (e.g., top soil, surface water, ground water). Chromium (III) is an essential nutrient that helps the body use sugar, protein, and fat ⁽²⁸⁾. Chromium (VI) is the second most stable form; it is found naturally in anaerobic environments, such as sediments. Chromium (IV) compounds are readily reduced to chromium (III) in the presence of oxidizable organic matter.

Inhaling or ingesting small amounts of chromium will not cause illness or injury. ATSDR does not have an intermediate or chronic MRL for chromium. EPA has set its reference dose (RfD) for chronic ingestion of chromium (VI) at 0.005 mg/kg/day and for chronic ingestion of chromium (III) at 1.00 mg/kg/day ⁽²⁸⁾. An RfD is an estimate of the daily human exposure to a contaminant, over a lifetime, below which non-cancer health effects are unlikely to occur. Chromium ingestion by children playing on site should not cause illness or injury, except in individuals who are chromium sensitive. Those individuals may have dermatitis or skin irritation and inflammation. Chromium sensitivity, which is uncommon, usually develops after prolonged contact.

Copper

Copper, a reddish metal that occurs naturally in rock, soil, water, sediment, and air, as well as in plants and animals, is an essential element for all known living organisms including people and other animals. Food naturally contains copper. An individual typically will ingest about 1mg copper a day through normal eating and drinking. Children at NHPC were exposed to copper in surface water and sludge on the site. ATSDR does not have MRLs for copper, and EPA has no RfD for its ingestion. Children playing in surface water and sludge at NHPC should not experience severe health effects as a result of their copper exposure. Minor health effects that could occur following infrequent exposure to copper include diarrhea, abdominal pain, and vomiting ⁽²⁹⁾.

Lead

Lead, a naturally occurring bluish-gray metal found in small amounts in the earth's crust, was found in sludge and soils at NHPC. Lead exposure is particularly dangerous for unborn children and young children because they are more sensitive to it during their development ⁽²⁵⁾. The American Academy of Pediatrics considers lead a significant hazard to the health of children in the United States ⁽³⁰⁾. The Centers for Disease Control (CDC) guidance on blood lead levels in children is 10 g/dl. ATSDR has no MRL, and EPA has no RfD for lead. Blood lead levels were not measured in children who played on the site. However, estimates of blood lead levels for children exposed to maximum lead levels in surface soil/sludge are not expected to reach 10 g/dl. Therefore, exposure to lead from on-site sources at NHPC are not expected to result in adverse health effects ⁽⁴⁴⁾.

Nickel

Tin , a soft, white, silvery metal found in small amounts in the earth's crust, is insoluble in water. Because simple tin compounds enter and leave the body rapidly, they are not usually associated with harmful effects. Too much exposure to tin compounds can cause stomachaches, blood changes, liver and kidney effects, and skin and eye irritation ⁽32). Children playing at NHPC were exposed to tin in surface water and sludge on site. No specific populations unusually susceptible to health effects of inorganic tin compounds have been identified. ATSDR does not have MRLs for tin. EPA's RfD for tin ingestion is 0.62 mg/kg/day ⁽³²⁾. The estimated doses of the children's tin exposure were well below the RfD; therefore, illness or injury are not expected.

Zinc

Zinc, one of the most abundant trace metals in humans, is found in all tissues and tissue fluids and is part of many enzyme systems ⁽³³⁾. Children were exposed to zinc at NHPC in surface water, dried sludge, and soil on site. The children's estimated exposure to zinc in the lagoon sludge was lower than the RfD comparison values for ingestion of zinc. Therefore, no illness or injury from exposure to the estimated dose is expected.

Many different metals and nutrients affect the absorption, distribution, and excretion of zinc. Information about interactions resulting in increased zinc toxicity or increased toxicity of other substances in the presence of zinc was not found ⁽³³⁾.

Cyanides

Cyanides are compounds composed of a common structure, which is formed when elemental nitrogen and carbon are combined. They are produced by certain bacteria, fungi, and algae and are found in many foods and plants. Of the cyanide compounds, hydrogen cyanide, sodium cyanide, and potassium cyanide are those most likely to be found in the environment as a result of industrial activities. Cyanide salts and hydrogen cyanide are used in electroplating ⁽²⁴⁾. Cyanide is a powerful and rapid-acting poison. Exposure to high levels (1.52 mg/kg) for a short time damages the brain, lungs, and heart, and may cause coma and death. Cyanide's effects, regardless of exposure route, are similar after inhalation, ingestion, or skin contact ⁽³⁴⁾.

Children playing at NHPC were exposed to cyanide in surface water and sludge. Although the exact half-life of cyanide in water is not known, it is believed to be short ⁽²⁴⁾. Most cyanides in water form hydrogen cyanide and evaporate. Some cyanides in water are transformed into less harmful chemicals by microorganisms in the water or by forming a complex with metals, such as iron. ATSDR does not have MRLs for cyanide ingestion. The estimated dose of cyanide to which children playing on the site were exposed does not exceed the chronic oral RfD of 0.02 mg/kg/day. No data indicate that cyanides are carcinogenic. EPA has assigned cyanide a D classification, i.e., it is not possible to determine the potential of cyanide to cause cancer in people. The children's ingestion of cyanide at the estimated dose is not expected to cause illness or injury.

Carbon Tetrachloride (CCL₄)

CCL4, a clear, heavy liquid with a sweet odor, evaporates readily; therefore, CCl₄ is not often found in liquid form in the environment. Most CCl₄ is found as a gas in the atmosphere. Small amounts also are found dissolved in water. In air, CCL₄ concentrations of 0.1 ppb are common around the world; higher concentrations (0.2 to 0.6 ppb) are found in cities (35). Children at the NHPC site were exposed to CCl4 as a result of ingesting surface water and contacting (skin) surface water on the site. The acute oral MRL for CCL₄ is 0.2 mg/kg/day; the intermediate MRL is 0.007 mg/kg/day (35). ATSDR does not have a chronic MRL; EPA's RfD is 0.0007 mg/kg/day. The estimated dose of children who contacted surface water containing CCl₄ does not exceed either the MRLs or the RfD. Hence, no non-carcinogenic adverse health effects are expected after exposure at the estimated doses to CCL₄ at the site.

Although CCL₄ is classified by the EPA as a Group B2 probable human carcinogen, the estimated exposure to this compound is expected to result in a negligible increase in carcinogenic risk.

1,2-Dichloroethane (1,2-DCE)

1,2-DCE, a clear, synthetic liquid not found naturally in the environment, evaporates at room temperature; it has a pleasant smell and sweet taste. Small amounts of 1,2-DCE released into water or onto soil first evaporate into the air. Since it is readily broken down by sunlight, 1,2-DCE does not stay in the air very long. 1,2-DCE remaining on soil after a spill or improper disposal can move through the ground into water; it can remain in water or soil for long periods. ATSDR does not have intermediate and chronic MRLs for ingestion of 1,2-DCE; the acute MRL is 0.005 mg/kg/day ⁽³⁶⁾. The estimated dose of 1,2-DCE to which people may have been exposed in surface water was less than the acute MRL. Neither illness or injury is expected following acute exposure to 1,2-DCE at the estimated dose.

1,1,1-Trichloroethane (1,1,1-TCA)

1,1,1-TCA is a colorless synthetic chemical. In the environment, it can be a liquid or a vapor, or exist dissolved in water and other chemicals. It also may exist as a liquid in soil and as a vapor in air. 1,1,1-TCA has a sweet yet sharp odor. Animal studies have not shown that 1,1,1-TCA in the air or water causes cancer or affects reproduction; however, some studies are not complete. Swallowing large amounts of 1,1,1-TCA has caused liver damage and death in animals and could be harmful to humans. EPA has assigned 1,1,1-TCA a carcinogenic classification of D, i.e., it cannot be classified with regard to whether it causes cancer in humans.

There are no MRLs or RfDs for 1,1,1-TCA, but because 1,1,1-TCA levels in NHPC surface water were very low, any ingestion by children playing on the site would have been negligible. Therefore, exposure at the dose estimated to have existed at NHPC would not be expected to cause illness or injury.

Trichloroethene (TCE)

TCE is a nonflammable, colorless liquid at room temperature with an odor similar to ether or chloroform. The nervous system is probably most susceptible to illness or injury as a result of chronic TCE exposure. TCE exposure at the NHPC site occurred by way of ingestion and by skin contact with surface water. The most recent monitoring study at NHPC found levels of 0.04 ppm in surface water and 0.03 ppm in groundwater. ATSDR has derived an intermediate MRL for TCE ingestion of 0.1 mg/kg/day, using what is known about TCE's ability to cause liver damage. An EPA workgroup is reviewing the oral reference dose (RfD) for TCE. EPA classified TCE as B2, a potential human carcinogen, i.e., TCE has caused cancer in one animal species; that classification has since been withdrawn pending further review. The estimated dose of TCE from surface water believed to have existed at NHPC is much lower than the intermediate MRL. Therefore, no non-carcinogenic adverse health effects are anticipated as a result of this type of exposure. Carcinogenic risk from this type of TCE exposure is expected to be negligible.

Table 14.Comparison of Estimated Exposure Dose of Children Playing on Site to Health Guidelines

a = Free Cyanide and Hydrogen Cyanide
NA = Not available

Children at the Former Avanti Day Care Center

Children at the Former Avanti day care center were occasionally exposed to cyanide and cadmium during site remediation. Exposure was by way of inhalation.

Cyanide

As reported earlier in this public health assessment, cyanide was detected in ambient air three times at the day care center monitoring station; the maximum concentration measured was 0.026 mg/m3. There are no MRLs for acute, intermediate, or chronic exposure to cyanide by way of inhalation; similarly, EPA has no RfDs for cyanide. At least nine states, however, have regulations and/or guidelines for acceptable ambient air concentrations of cyanide and its derivatives ⁽³⁴⁾. The amount of cyanide detected at the day care center is well below the lowest reported state regulation (0.1 mg/m3 for a 1-hour exposure, 0.2 mg/m3 for an 8-hour exposure, and 0.08 mg/m3 for a 24-hour exposure). It is unlikely that cyanide exposure at those concentrations could cause illness or injury.

Cadmium

Cadmium was also detected in ambient air at the day care monitoring station (maximum concentration: 0.0003 mg/m3) (Table 15). Although the maximum concentration detected exceeds the chronic MRL, cadmium was detected only once in the ambient air around the day care center probably as a result of ongoing remedial activities at the time. Based on this data, no adverse health effects are anticipated to result from cadmium exposure of children at the Avanti Day Care Center.

Table 15.Comparison of Estimated Exposure Doses of Children at the Day Care Center to Health Guidelines

^a There are no health guidelines for comparison with estimated exposure doses.
NA = Not available

Workers at NHPC

Workers at the NHPC site were exposed to cadmium, chromium, zinc, nickel, and tin (Table 16). Before operations ceased in 1985, exposure to contaminants occurred by way of ingestion of dust and other small particles over an estimated 20 year period beginning in 1962. To estimate ingestion exposure, it was assumed that the typical worker ingested about 200 mg of dust/day during 260 days of exposure over the course of a year. Indoor air monitoring data were not provided to ATSDR; as a result, an estimated inhalation dose could not be calculated.

Cadmium

Workers who inhale cadmium for a long period (chronic inhalation) may have an increased chance of developing lung cancer ⁽²⁷⁾. The estimated exposure dose of adults working in the facility exceeded ATSDR's chronic ingestion MRL of 0.0002 mg/kg/day. Since the estimated exposures were high, those persons may have experienced (and may continue to experience) illness or injury, although none have been reported to ATSDR. Proteinuria, kidney tubule dysfunction, and reduced urine are some expected effects of exposure ⁽²⁷⁾. Cigarette smoke exposes the general population to higher than average levels of cadmium. Smokers with occupational exposure to cadmium are at highest risk for illness or injury. Although cadmium is classified as a probable carcinogen when exposure is by way of inhalation, neither human nor animal studies provide sufficient evidence to determine whether cadmium causes cancer when exposure is oral.

Chromium

NHPC workers were exposed to chromium by ingesting dusts and other small particles at the facility. More data are available on the effects of chronic inhalation exposure in people and animals than there are on the effects of oral exposure. ATSDR was not provided with data on chromium concentrations in air inside NHPC. The respiratory system and the skin are the primary target organs for occupational exposure to chromium and its compounds ⁽²⁸⁾.

The literature did not report any target organ toxicity in animals from chronic oral exposure to chromium (III) and chromium (VI) compounds. This lack of toxicity may have been because of the poor absorption of chromium through the gastrointestinal tract. The estimated exposure dose of chromium of workers at the NHPC facility exceeded the chronic RfD for ingestion of chromium (VI). However, exposure at the estimated doses is not expected to cause illness or injury, except in chromium sensitive sub-populations. In that population, skin irritation is expected. Chromium is classified as a human carcinogen, and occupational inhalation studies indicate a correlation between long-term exposure to chromium (VI) compounds and lung cancer. Occupational studies generally are concerned with inhalation exposures. Cancer studies have shown that chronic inhalation of chromium (VI) compounds is carcinogenic in mice. Conversely, chronic oral exposure to chromium (VI) did not have significant carcinogenic effects ⁽²⁸⁾.

Although there are no data on indoor air quality at NHPC, it can be assumed that workers were exposed to chromium by way of inhalation. Lung cancer may occur long after exposure has ended. It is not clear which form(s) of chromium cause lung cancer in workers. Chromium (VI) is believed to be primarily responsible for increased lung cancer rates in workers exposed to high levels of chromium in air. Occupational exposure to chromium (III) compounds may not be as great a concern as chromium (VI) exposure. Oral exposure to chromium is not believed to cause cancer.

Nickel

Workers were exposed to nickel inside the NHPC facility. Cancer of the lung and nasal sinus is the most serious effect of chronic nickel exposure in humans, but it also effects the heart, blood, and kidneys, and may cause allergic reactions. The literature reports an increased death rate from lung diseases in people who inhaled nickel while working ⁽³¹⁾. An increased rate of cancers of the lung and the nose were also observed in workers exposed to nickel. EPA classifies nickel refinery dust and nickel subsulfide as Group A human carcinogens while nickel carbonyl is classified as a Group B2 carcinogens.

ATSDR does not have MRLs for nickel ingestion. EPA's RfD (oral) for soluble nickel compounds is 0.02 mg/kg/day. The estimated dose of nickel ingested by workers at NHPC, however, is much less than the RfD and should not cause non-carcinogenic adverse health effects.

Tin

Workers at the NHPC facility also were exposed to tin by ingesting dust and other small particles. ATSDR does not have MRLs for tin ingestion. EPA's oral RfD for inorganic tin is 0.62 mg/kg/day. The estimated exposure dose for workers at the NHPC facility was much less than that value, therefore, neither illness nor injury is expected.

Zinc

Workers also were exposed to zinc inside the NHPC facility. No relationship between the occurrence of cancer in humans and occupational exposure (primarily by way of inhalation) to zinc has been demonstrated ⁽³³⁾. No data were available on respiratory effects in people or animals following oral exposure to zinc or zinc compounds. Several studies have suggested that ingestion of zinc may cause symptoms of gastrointestinal distress or alterations in gastrointestinal tissues ⁽³³⁾. The type of zinc compound at the NHPC facility is unknown; however, the estimated ingestion dose of zinc at NHPC does not exceed the RfD comparison value of 0.3 mg/kg/day; therefore, no illness or injury is expected.

Table 16.Comparison of Estimated Exposure Dose of NHPC Workers to Health Guidelines

Recreators at Horseshoe Pond/Merrimack River

Sediment and Surface Water

Exposure to Merrimack River surface water and sediment contaminant levels in areas proximal to the site is not expected to result in adverse health effects. Concentrations of VOCs, metals and cyanide in Merrimack River surface water and sediment were either below detection or within the range of normal background.

Exposure to Horseshoe Pond sediment and surface water is not expected to results in any adverse health effects. Current levels of site related contaminants are either below detection or within the range of normal background. Maximum concentrations of cadmium (2 ppb) and cyanide (580 ppb) detected in Horseshoe Pond surface water during 1982 sampling are not expected to cause adverse health effects for recreators who have used the pond in the past.

Fish

Based on surface water and sediment sampling data, fish in the Horseshoe Pond and Merrimack River are not expected to bioaccumulate site related contaminants. However, it should be noted that NHDPHS has issued a Fish Ingestion Advisory for Horseshoe Pond based on elevated mercury levels in found in largemouth bass. The elevated mercury levels detected in Horseshoe Pond fish are not thought to be related to the NHPC site.

Private Well Users

Residents who use water from the private well on Daniel Webster Highway were exposed to 1,1-dichloroethane, 1,1-dichloroethene (DCE), 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethane tetrachloroethene (PCE), and trichloromethane (chloroform) by way of inhalation, ingestion and/or dermal contact. Available MRLs and RfDs which are listed below for these VOCs were not exceeded and thus no non-carcinogenic adverse health effects are anticipated to result from the use of this well.

Based on the March, 1990 sample of this private well, an ATSDR Health Consultation concluded that no adverse health effects would result from use of this well. An additional sample taken in August, 1993 detected similar VOC contamination with some VOCs detected at higher levels than the previous sample. Although VOC levels detected in this more recent sampling are still not expected to result in non-carcinogenic adverse health effects, the continued presence of multiple carcinogenic VOCs at the levels detected indicate a low increase in carcinogenic risk. This prompted NHDPHS to recommend that the well not be used for drinking purposes and that showering use be minimized ⁽⁴³⁾.

B. Health Outcome Data Evaluation

Health outcome data were not evaluated for this site because the population of concern (50-75 residents) is very small. As a result, it would be very unlikely that any health effects associated with the site could be detected. No previous health studies on the population near the NHPC site were identified during the gathering of data for this public health assessment, and no community concerns were expressed about possible health outcomes.

Table 17.Comparison of Estimated Exposure Dose of Private Well Users to Health Guidelines

NA = Not available

C. Community Health Concerns Evaluation

1. Is it advisable to eat fish from, swim in, or use water for irrigation from Horseshoe Pond or the Merrimack River?
   
   It is likely that contaminated groundwater is discharging to Horseshoe Pond at the north bank adjacent to the YMCA property. In 1982, several surface water samples from the pond's northern bank contained elevated levels of cyanide and cadmium. Analysis of recent samples taken in a radial pattern around the pond did not find these or any other site related contaminants at levels of concern. Analysis of Merrimack River surface water and sediment samples were below detectable levels for site-related contaminants. Based on this more recent sampling, contact with sediment and surface water near Horseshoe Pond or the Merrimack River does not represent a public health hazard.
   
   The U.S. Fish and Wildlife Service sampled fish from Horseshoe Pond at the request of EPA. Fish tissue was analyzed for the presence of PCBs and several metals. Cadmium was not detected at levels of public health concern. Mercury, however, was detected at levels which prompted the New Hampshire Division of Public Health Services (NHDPHS) to issue a Fish Ingestion Advisory for Largemouth Bass taken from the pond. The data was analyzed in a Health Consultation released by ATSDR in conjunction with NHDPHS (see Appendix D-5). The New Hampshire Plating Co. site is not believed to be the source of the elevated mercury levels in the fish taken from Horseshoe Pond.



2. Is it safe to build a ball-field on the property across the street from the site owned by the YMCA?
   Who will monitor the groundwater beneath the property for contamination?
   
   Using information obtained during evaluation of contaminant movement from the NHPC site (Environmental Pathways Section), it is unlikely that there has been any appreciable contamination of soil or ambient air with site-related contaminants. Soil and ambient air would be the likely media to which children would be exposed if a ball-field was built on the YMCA property. Groundwater beneath the YMCA property is contaminated because of the site; however, children or others playing on the proposed ball-field would not be exposed to those contaminants unless the contaminated groundwater beneath the property is to be used as a source of drinking water (i.e. drinking fountain). Municipal water supplies from the MVWD are now available in the NHPC area and at the YMCA property. Again, as indicated previously, a potential concern exists if the northern bank of the YMCA property is used for swimming.
   
   Any future groundwater monitoring of the site would likely be performed by EPA; therefore, this concern will be forwarded to them.



3. Who will sample the monitoring wells and how often? Will the Merrimack Health Officer receive a copy of the results?
   
   Any future sampling of groundwater monitoring wells at the site will likely be performed by EPA; therefore, this concern will be forwarded to them. The Merrimack Health Officer should contact the EPA Remedial Project Manager for the site to arrange to receive monitoring results as they are available.



4. If the contaminated materials are not removed for 10 years, is there something that can be done in the meantime to mitigate the contamination? Also, whatever is done, how often and by who will the site be inspected?
   
   Under Superfund legislation, the EPA is responsible for remediating the NHPC site; therefore, these concerns will be forwarded to them. It is important to note that this public health assessment evaluates not only past and current public health concerns, but also those that may arise in the future. The conclusions and recommendations of this public health assessment, therefore, are intended to stop or reduce future exposure to site contaminants.



5. Has there been appreciable contamination of air around the site as a result of removal and remedial actions?
   Yes, the air around the site was contaminated during removal and remedial actions. During the excavation and treatment of soils and sludge material, ambient air samples were collected. No detectable concentrations of organic vapors or hydrogen cyanide were detected. Cyanide and chromium were detected in on-site air samples at very low levels. Cyanide was detected eight times in off site samples; the highest level was 0.026 mg/m³. The levels of contamination measured in air around the site during removal and remedial activities are not of public health concern.



6. Could the on-site underground storage tank leak and cause further contamination?
   
   The on-site underground storage tank was removed by EPA in December 1994 at the time the NHPC building was demolished and removed. This has eliminated the storage tank as a possible source of groundwater contamination except for any residual soils that were previously contaminated by leaking of the underground tank.



7. Is the former NHPC building a public health concern if left standing?
   
   The site was fenced by EPA in 1991 which effectively limited the hazard posed by the building and the site in general to trespassers.
   
   Demolition and removal of the NHPC building began in early December, 1994 and was completed before the end of the month. The removal operation also included regrading and a temporary cover over the former building location to prevent rainwater infiltration of the soil.



8. Is drinking water of acceptable quality being provided to residents in the area? Should a well survey be conducted to determine the number of people using municipal and/or private well water?
   
   One off-site well on Daniel-Webster Highway which has been sampled twice has shown low levels of VOC contamination. Levels of VOCs in this well are below regulatory guidelines and are not anticipated to cause an non-carcinogenic adverse health effects. However, the presence of several Class C possible human carcinogens in this well has prompted NH DPHS to recommend that this well not be used for drinking purposes. More sampling of this well is needed to update this analysis.
   
   ATSDR believes that no private domestic wells drawing water from the overburden aquifer are affected by contaminants migrating from the site in groundwater. Because of the lack of information on the extent of contamination and direction of groundwater flow in the bedrock aquifer, however, it cannot be determined if the NHPC site is affecting the quality of water in private wells that draw from that aquifer. It is believed that people using water from MVWD are being supplied drinking water of acceptable quality.
   
   A well survey is not needed because private wells in the area served by MVWD were identified in 1990 for the ATSDR Site Summary Report ⁽⁷⁾. Furthermore, information from the Merrimack Health Officer indicates that private wells probably would not be installed in the contaminated plume area west of the Merrimack River because municipal water supplies are available ⁽⁹⁾.



9. Are other sources of contamination near the NHPC site contributing to the problem? Are those sources contributing to contamination of the Merrimack River?
   
   Evaluations performed at several industries and commercial properties near the NHPC site indicate it is likely that other sources of contamination exist. Furthermore, numerous industries and commercial enterprises are adjacent to NHPC and the Merrimack River, as well as up- and downstream from the site. Therefore, it is likely that other sources are contaminating the Merrimack River.



10. Is the contamination of Lagoon #5 a health concern; should the area be fenced to prevent access?
    
    Lagoon #5 is also known as the undefined wetland north of Lagoon #3. Several contaminants have been detected in soils from the undefined wetland at concentrations of public health concern. Children could have been exposed to contaminants found in the undefined wetland from the 1960s through 1987-1989. The site perimeter fence, built in 1991, encloses Lagoon #5 and, therefore, limits exposure to those contaminants.



11. How stable is and what is the life-expectancy of the liner covering the contaminated soil in the on-site holding cell?
    
    Because the liner was installed and will be maintained by EPA, this concern has been forwarded to EPA. It is believed that the holding cell is stable and that the life expectancy (20 years) is sufficient to contain the soils until a permanent remedy can be implemented.



12. Was it safe for on-site workers to eat raspberries from plants outside the site perimeter fence?
    
    Our evaluation of the possible routes of contaminant migration (environmental pathways) from the NHPC site indicates it is highly unlikely that appreciable site contaminants have accumulated in the raspberry plants outside the site perimeter fence. Therefore, raspberries from those plants were probably safe to eat.



13. What is the public health impact of residential gardening in areas adjacent to the site?
    
    Our evaluation of the possible routes of contaminant migration (environmental pathways) from the NHPC site indicate it is highly unlikely that appreciable site contaminants have migrated from the site to off-site soils in which residential gardens are planted. Furthermore, it is also highly unlikely that site-related contaminants were in water used on those gardens. As a result, vegetables or fruits from those gardens are probably safe to eat.

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