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The tables in this section list the contaminants of concern. The contaminants are evaluated insubsequent sections of this public health assessment, and it is determined whether exposure tothem has public health significance. ATSDR selects and discusses contaminants using thefollowing 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 acontaminant 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 healthassessment.

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 mediaused to select contaminants for further evaluation. Those values include environmental mediaevaluation guides (EMEGs), cancer risk evaluation guides (CREGs), reference dose mediaevaluation guides (RMEGs) and other relevant guidelines.

EMEGs are media-specific comparison values that are used to select contaminants of concern athazardous waste sites. EMEGs are derived from the Minimal Risk Levels (MRLs) presented inthe ATSDR Toxicological Profiles. An MRL is an estimate of daily human exposure to achemical that is likely to be without a substantial risk of harmful (noncancerous) effects over aspecified 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. RMEGsare media-specific comparison values that are used when EMEGs are not available. RMEGs arederived from RfDs.

CREGs are estimated contaminant concentrations based on the incidence of one excess cancer ina million persons exposed over a lifetime. CREGs are calculated from EPA's cancer slopefactors. EPA's maximum contaminant level goal (MCLG) is a drinking water health goal. Maximum contaminant levels (MCLs) are contaminant concentrations in water that EPA deemsprotective of public health (considering the availability and economics of water treatmenttechnology) 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. Thecollection 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 perimeterfence.

Waste Material-Lagoon Surface Water and Effluent (wastewater)

Between September 1981 and July 1986, 41 samples of lagoon water and 28 samples of effluentwere analyzed. Between September 1983 and October 1984, samples of effluent from the NHPCoperation, which discharged into the NHPC lagoon, and surface waters of the Lagoon #1 werecollected monthly and analyzed for cyanide. Most of the other samples collected from thosemedia were analyzed for volatile organic compounds (VOC) and for selected inorganiccompounds (1). The maximum contaminant concentrations for the on-site lagoon surface waterand 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
RefComparison Valuea
Cadmium17.0 1.007EMEG
Chromium (VI)5.3b1.050EMEG
Chromium-total 15.0710.0EMEG
Total Cyanide140.07.200RMEG

a- EMEG and RMEG comparison values reported for children.
b- Value for chromium +6 obtained from one sample of effluent--corresponding total chromiumvalue 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 analyzedprimarily for selected heavy metals and cyanide. The most comprehensive sampling of theextent of contamination in the lagoon area was performed by EPA in October 1989. Oneobjective of that sampling was to determine the vertical and lateral extent of contamination in thefour on-site lagoons. A total of 163 sludge samples, at depths ranging from 0-12 feet, wereobtained in a grid fashion from the four lagoons (12). The 0-foot samples were obtained within thefirst 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 heavymetals 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 thatmost 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 inTable 2. Those data reflect contaminant levels before lagoon remediation (i.e., removal) began.


In May 1987, five soil samples were obtained from beneath the NHPC facility building. Thecomposite samples were obtained at a maximum depth of 18 inches (2). In addition, during thecomprehensive 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 tothe lagoons, and as part of an ecological study (11,12). Samples were collected at depths rangingfrom 0-12 feet. Surface soil samples were collected at a depth of 0-3 inches (13). The 1987 soilsamples were analyzed for selected heavy metals and cyanide. Of the 34 samples collected inOctober 1989, 27 were analyzed for selected heavy metals, four for the same heavy metals andcyanide, and three for cyanide only (12).

Table 2.

Maximum Contaminant Concentrations of Waste Material-Lagoon Sludge
Contaminant Maximum
Ref. Comparison Valuea
(ppm) Source
Cadmium 89,200b/16,000c 1,12 40 EMEG
Chromium-total 28,000c 12 300d/50,000e RMEG
Copper 62,000b 1 300f RMEG
Lead 1,100b/430c 12 NA NA
Nickel 16,000c 12 1,000g RMEG
Tin 26,000c 12 NA NA
Zinc 160,000c 12 20,000 RMEG
Total Cyanide 23,700c 12 1,000 RMEG

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 byVOCs and heavy metals at the site. The NHPC site (excluding lagoons) was partitioned intothree 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 heavymetals. 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 VOCanalysis; 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 soilcontaminant concentrations are summarized in Table 3. Those values are for contaminantconcentrations 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)
Ref.Comparison Valuea
Chromium-total470/800b 11300c/50,000dRMEG
Lead448 14NANA

a- EMEG and RMEG comparison values reported for children.
b- Value represents an on-site screening concentration only-- sample was not sent to laboratoryfor 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 bysweeping 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 NHPCbuilding. Ambient air throughout the building was screened for VOCs and combustiblegases--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 collectedand screened for VOCs; three soil samples were collected and screened for heavy metals; andone duplicate sample was collected and sent to the EPA laboratory for VOC and heavy metalanalysis. In addition, four bulk asbestos samples were taken--two from an air-cell-type pipeinsulation and two from ceiling tiles. Asbestos was found at a maximum 30 % in one pipeinsulation sample--the type of asbestos found was chrysotile. Asbestos was not found in twoceiling tile samples (14). The maximum contaminant concentrations in the NHPC building weredetected in samples of dust and other small particles--those data are summarized in Table 4.

Table 4.

Maximum Contaminant Concentrations in NHPC Building Interior
Ref.Comparison Valuea

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 wereinstalled and sampled. In addition, two on-site bedrock monitoring wells were installed andsampled. Sampling of those wells was initiated by NHPC, NHDES, and EPA. In June 1990, 13on-site monitoring wells were analyzed for total cyanide, dissolved metals (filtered samples), andVOCs; 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 wereanalyzed for VOCs, heavy metals, and total cyanide--those samples were not filtered beforeanalysis. Groundwater samples from on-site bedrock monitoring wells were not analyzed forheavy metals. Samples collected in December, 1993 as part of the RI/FS were analyzed forVOCs, total metals and cyanide. Five metals and eight VOCs were detected at levels above theirrespective MCLs.

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

Table 5.

Maximum Contaminant Concentrations in On-site Groundwater Monitoring Wells
RefComparison Valuea
Total Cyanide1,5507200eRMEG
Xylenes-o and p1,500110,000LTHA
Isobutyl ketone3577NANA

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 toNovember 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 monitoringsystem 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 hydrogencyanide generation. No detectable concentrations of organic vapors or hydrogen cyanide weremeasured. One of the off-site monitoring stations is located directly behind the nearby childdaycare center. The monitoring devices at those stations sampled for cadmium, chromium, andcyanide dusts. Conditions during collection of most samples were hot (greater than 80 oF)anddry(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 isshown in Table 6.

Table 6.

Range of Contaminant Concentrations in On-site Air Samples
Ref.Comparison Value
Total CyanideND-0.0329NANA
Total ChromiumND-0.00398.0X10-8CREGa

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 fromHorseshoe Pond contained the three highest concentrations of cyanide found in any sample ofwater from Horseshoe Pond (i.e., 50, 160, and 580 ppb). One 1982 pond sample containedcadmium at 2 ppb. A more recent analyses of water from Horseshoe Pond carried out under theRI/FS in July of 1993 yielded non-detect results for cyanide, VOCs and metals includingcadmium (18).

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

Table 7.

Range of Contaminant Concentrations in Off-Site Surface Water
Range (ppba)
RefComparison Valueb
Total cyanideND-5801,18200dRMEG
Volatile organiccompoundsND1,18NRNR

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 sampleswere analyzed for cadmium, total chromium, chromium +6, and total cyanide (19). Sedimentsampling of Horseshoe Pond was conducted in July of 1993 as part of the RI/FS. Sedimentsamples were taken in a radial pattern around the pond and analyzed for metals, cyanide, VOCsand semi-volatile organic chemicals (SVOCs)(42). Contaminant concentrations in off-sitesediment from the Merrimack River and Horseshoe Pond are summarized in Table 8.

Table 8.

Range of Contaminant Concentrations in Off-Site Sediment
Range (ppm)
Comparison Valuea
Chromium (VI)NDNANA
Total cyanideNDNANA

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 toWright Avenue across the street from NHPC (i.e., the YMCA property). Those off-site sampleswere obtained and screened in the same manner as on-site soil samples. One duplicate samplewas sent to the EPA laboratory for heavy metal analysis and confirmation. Heavy metals werenot 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 atthe site. During the June through August 1990 excavation period, cyanide was detected eighttimes at off-site monitoring stations. Cyanide was detected three times at the day care centermonitoring station; the maximum cyanide value detected was 0.026 mg/m3--this was themaximum value detected off-site. Cadmium was detected in only one on- or off-site sample--theday care center (17). Contaminant concentration ranges for off-site ambient air are summarized inTable 9.

Table 9.

Range of Contaminant Concentrations in Off-site Air Samples
Ref.Comparison Value
Total cyanideBD-0.02617NANA
Total ChromiumBD178.3X10-8CREGa
    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 numerousoccasions. During that period, 36 off-site surficial aquifer monitoring wells were installed andsampled. In addition, three off-site bedrock monitoring wells were installed and sampled. Onebedrock 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 samplesfrom off-site monitoring wells were analyzed for total cyanide, dissolved metals (filteredsamples), 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 wereanalyzed for VOCs, heavy metals, and total cyanide. Further sampling was carried out inDecember, 1993 as part of the RI/FS. The maximum contaminant concentrations detected inoff-site groundwater were from samples taken from the overburden aquifer--those concentrationsare shown in Table 10.

Several VOCs were detected above their comparison values in groundwater samples fromoff-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 thetrichloroethene were detected in water samples from the Jones Chemical Production well. Several heavy metals and cyanide were detected at concentrations below their respectivecomparison 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 productionwell, both on Daniel Webster Highway, were analyzed for VOCs. The private well wasresampled in August of 1993 (43). Two nearby MVWD municipal water supply wells aremonitored monthly for lead and copper and annually for VOCs, radon, and other prioritycompounds (20). No contaminants were detected in samples from these two off-site municipalwells.

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

Table 10.

Maximum Contaminant Concentrations in Off-site
Groundwater Monitoring Wells
Ref.Comparison Valuea
Total Cyanide3901200RMEG
    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.

Table 11.

Maximum Contaminant Concentrations in Off-site
Private Water Supplies
Ref.Comparison Value

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

C. Toxic Release Inventory Data

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

D. Quality Assurance and Quality Control

Data on quality assurance/quality control (QA/QC) techniques used during preparation of thispublic health assessment were not available for review. It is believed, however, that most of thedata 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 havepassed strict QA/QC requirements.

E. Physical and Other Hazards

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


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

ATSDR categorizes exposure pathways as either completed or potential. For a completedpathway to exist, five elements must be present and there must be evidence that exposure to acontaminant has occurred, is occurring, or will occur. A pathway is potential when at least oneof the five elements is missing, but could exist. Potential pathways indicate that exposure to acontaminant could have occurred, could be occurring, or could occur in the future. An exposurepathway 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'spotential exposure pathways. The discussion following the two tables address only pathwaysimportant and relevant to the site. Also discussed are some of the eliminated pathways and thoseabout which there is community concern.

Table 12.

NHPC Waste
NHPC On-siteactivities
Surface water
On-site Lagoons and
Skin contact
playing on site(20)
Ambient AirNHPC
AirDay Care CenterInhalationChildren (20)Past
Interior NHPC
Dusts and Othersmall particlesWork SurfacesInterior NHPCBuildingIngestion NHPC
workers (30)
Private Well
(Daniel Web.Hwy)
Site-unrelatedGroundwater Residential
Skin contact
Residents usingprivate well

( ) - Estimated exposed population.

Table 13.

NHPC Waste
Lagoon Waste
AirOn-site Lagoons InhalationChildren PlayingOn-sitePast
Private WellsNHPCGroundwaterPrivate Wells
Skin contact
Users of Private
wells in Litchfield
Merrimack RiverNHPCFish
Surface Water
Merrimack RiverIngestion
Skin contact
Recreational use ofMerrimack River Past
NHPC WorkersWork Surfaces/Interior NHPCBuilding AirInterior NHPCBuilding InhalationNHPC workersPast
Pond (Surfacewater and
NHPCSediment Surfacewater Horseshoe PondIngestion
Skin contact
Recreational users ofHorseshoe PondPastPresentFuture
Horseshoe Pond(Fish)Site-unrelatedmercuryGroundwater
Surface Water
FishIngestionConsumers of fish fromHorseshoe PondPast

A. Completed Exposure Pathways

NHPC Waste Material Pathway

Since children played on-site before site restrictions were in place, they were probably exposedto on-site waste material. Waste materials included lagoon sludge, soils, and surface water. Thegreatest exposure to contaminants was from the waste materials in the lagoon system, althoughsoils at other on-site locations also were probable points of exposure. It is likely that exposure tolagoon 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 primarilybecause 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 ofother on-site soils probably resulted from other disposal methods or from leaks from pipes orstorage tanks. The results of the extensive characterization of on-site soils near the perimeter ofthe site and the lack of a mechanism for transport of contaminants to off-site soils indicate thatmost, 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 forchildren younger than 6 years (22). Soil ingestion typically is greater for young children becauseof their greater hand/mouth activity. Because the ages of the children who played on site are notknown, however, it is difficult to determine the amount of soil they might have incidentallyingested. Furthermore, given the climatic conditions of New Hampshire, it is likely that coldweather and snow precluded recreational activities and contact with contaminated media at thesite during part of the years that children probably were exposed. Children could have beenexposed to contaminants at the site from the early 1960s until 1987-1989, when the lagoon fencewas erected and remedial actions began. The number of children who played on site and howoften they played there are not known. Given current conditions at the site, it is highlyimprobable that children now have appreciable exposure.

As shown in Tables 2 and 3, on-site surface sludge and soils have been contaminated with highlevels of heavy metals and cyanide. In addition, high levels of VOCs and heavy metals werefound in the NHPC effluent and in surface water in the lagoons (Table 1). EPA has remediatedthe most significant contaminant concentrations in the lagoon system (Table 2). Thecontaminant 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 possiblywere exposed in the past to contaminated ambient air during site remediation activities thatoccurred during summer, 1990 (Table 12). According to ambient air monitoring data at anoff-site sampling location behind the day care center, however, contaminants were detected onlyfour times during this time period. Cyanide was detected three times at a maximum value of0.026 mg/m3; cadmium was detected once at a concentration of 0.0003 mg/m3. Thoseconcentrations probably reflect a worst-case scenario of off-site dust generation at the sitebecause they were detected during remedial activity (i.e., when soils are disturbed) and duringhot and dry conditions. When remediation was not taking place on site, the lagoons were usuallywet 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 thedried 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 heavymetals (Table 4) through ingestion of dusts and other small particles on work surfaces in thebuilding (Table 12). The number of employees who worked at the site during its years ofoperation is not known. No future exposure pathways exist as the building was demolished inDecember of 1994.

Private Well Pathway

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

Since the contaminated private well is believed to supply a multiplex dwelling (presumably fourresidential units), ATSDR estimates that approximately 12 persons were exposed to severalvolatile organic chemicals (VOCs) by ingestion, inhalation, and skin contact. Since thosecontaminants evaporate into the air from water during showers or baths, people are exposed asthey breathe the air in their homes. In addition, the contaminants are absorbed through the skinduring showers and/or baths, increasing exposure (23). Although the source of the private wellcontamination is not known, and only two water samples from the well have been analyzed, it isimpossible 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 completelycharacterize 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 childrenbreathed VOCs and soil dusts containing heavy metals and cyanide (Table 13). The source ofthe VOCs was the effluent and surface water in the lagoons; the soil dusts were from the lagoonsludge, near-lagoon soils, and other on-site areas with soil contamination. The primary points ofexposure were the waste materials in the lagoon system and other on-site areas with soilcontamination. Table 12 and the Completed Exposure Pathways section provide additionaldetails 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 towhich the children might have been exposed. Because this pathway relates, in part, to localizedambient 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 heavymetals and VOCs in the on-site soils, sludge, effluent, and surface water (Tables 1-3), however, itis reasonable to assume that the ambient air pathway contributed to the total exposure of childrenwho 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. Contaminatedgroundwater in the overburden aquifer has migrated from on-site source areas south, east, andsoutheast. The direction of contaminant migration is consistent with groundwater hydrology inthe site area. The direction of contaminant migration in the fractured bedrock aquifer is notknown. 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 thebedrock and overburden aquifers intercept to form one aquifer system, however, it is likely thatsome contaminated groundwater moves in the same direction as groundwater in the overburdenaquifer (1). Hence, it is possible that contaminated bedrock groundwater has moved toward andunder 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 ahalf-mile radius of the site. These wells represent potential points of exposure to contaminatedgroundwater, particularly if they are bedrock wells (Table 13). The current bedrock monitoringnetwork does not, however, allow for characterizing that pathway. The Draft RI/FS has notadequately addressed this issue. It is unlikely that the two Litchfield public water wells, whichare operated by the SNHWC, could become contaminated because they are about 3-4 miles fromthe site, and they do not draw water from the bedrock aquifer.

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

Merrimack River Pathway

Surface Water and Sediment

The results of groundwater monitoring and hydrogeologic investigations indicate thatgroundwater contaminated with VOCs, cyanide, and possibly heavy metals, has migrated fromon-site contaminant source areas to off-site areas east and southeast of the site. Some of thosecontaminants have probably discharged into the Merrimack River. To date, surface water andsediment monitoring data have not shown elevated levels of site-related contaminants, exceptcyanide in one surface water sample (12 ppb). Sampling of Merrimack River surface waterconducted during the RI/FS yielded non-detect levels of VOCs, metals and cyanide. Sedimentsamples taken from the river during the RI/FS were non-detect for VOCs and within backgroundranges for metals.


Potential past, present, and future exposure to site contaminants that may bioaccumulate in fish ispossible for individuals who have eaten or eat fish from the Merrimack River (Table 13). Asindicated previously, however, the only contaminant detected at elevated levels in sediment andsurface water samples from the Merrimack River was cyanide, at 12 ppb. Fish bioaccumulatevery little cyanide into their bodies (24). Cyanide was detected in surface water only once at lowlevels; it was not detected at all in sediment samples. Therefore, it is not likely that fish arebioaccumulating 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 heavymetal-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 notpossible because current indoor air conditions do not represent conditions when the facility wasoperating (i.e., when workers were exposed). Specifically, remedial actions in the building haveprobably reduced ambient air dust levels; it is likely that the highest levels of contaminated dustsin ambient air were generated when workers disturbed contaminated work surfaces. Furthermore, given the high concentrations of heavy metals on work surfaces, ambient airexposure could have been significant.

Horseshoe Pond Pathway

Surface Water and Sediment

Results of groundwater monitoring and hydrogeologic investigations indicate that groundwatercontaining VOCs, cyanide, and possibly heavy metals has migrated from on-site contaminantsource areas to off-site areas south of the site. Contaminated groundwater probably discharges atthe northern shore of the outer bank of Horseshoe Pond. People swim near residential areasabout 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 watersamples taken during the RI/FS in July, 1993 did not detect VOCs, metals or cyanide abovedetection limits. Sediment sampling of Horseshoe Pond was conducted in July, 1993 as part ofthe RI/FS. Samples were taken in a radial pattern around the pond. Several metals were detectedat concentrations similar to background levels. Arsenic detected in one sample at a slightlyhigher 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 futureexposures to contaminants in these media are expected to be minimal.


As indicated previously, the only contaminants detected at elevated levels in surface watersamples from Horseshoe Pond were cyanide and cadmium. Fish bioaccumulate very littlecyanide (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 metalsincluding arsenic, cadmium, chromium, copper, lead, nickel and zinc. Cadmium was notdetected in any samples. Slight elevations in lead (HP-04) and arsenic (HP-06) concentrationswere noted when compared to a representative background sample (HP-01). These increases aremost likely due to background variability and do not represent a site related source. Lead andarsenic do not bioaccumulate in in the edible portion of fish and do not represent a hazard via thispathway.

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


A. Toxicological Evaluation

This section discusses health outcome data, health effects in individuals exposed to particularcontaminants, and specific community health concerns. To evaluate health effects, ATSDR hasdeveloped minimal risk levels (MRLs) for contaminants commonly found at hazardous wastesites. The MRL is an estimate of a level of daily human exposure to a contaminant below whichnon cancerous adverse health effects are unlikely. MRLs are developed for each route ofexposure (e.g., ingestion and inhalation) and for the length of exposure (e.g., acute, less than 14days; intermediate, 15 - 364 days; and chronic, 365 days or more). Because ATSDR has nomethodology to determine amounts of chemicals absorbed through the skin, the Agency does nothave MRLs for skin exposure. ATSDR presents information on MRLs in its series ofToxicological Profiles on hazardous substances. These chemical-specific profiles provideinformation on health effects, environmental transport, human exposure, and regulatory status. The following discussion uses information obtained from the ATSDR Toxicological Profiles toidentify 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, itwas assumed that the children would ingest 200 milligrams (mg) of soil or sludge (dried), duringan exposure period of 4 days. Exposures were estimated for 6-month periods. A surface wateringestion rate of 5 ml was used to estimate incidental ingestion of surface water by childrenplaying in the lagoons.


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 (0.07mg/kg, estimated dose for children weighing 35 kg or approximately 77 pounds) severelyirritates the stomach, leading to vomiting and diarrhea. Cadmium build up causes kidneydamage in some people, and can lead to problems in calcium metabolism. As a result, bonesbecome fragile and break easily. Skin contact with cadmium is not known to cause illness orinjury in people or animals. The kidney is the main target organ of cadmium toxicity afterextended oral exposure (27). Human studies have shown that prolonged cadmuim exposure canlead to a high incidence of abnormal kidney function, indicated by protein in the urine and adecrease in kidney function. Kidney abnormalities may increase in severity even after exposurehas 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 driedsludge, and their estimated exposure dose exceeded the chronic MRL of 0.0002 mg/kg/day forcadmium ingestion. The estimated dose suggests that there is a possibility of mild kidneydamage, indluding proteinuria, to occur. Proteinuria is the presence of increased protein in theurine. The estimated exposure dose for cadmium in the surface water and soil was below thechronic MRL for ingestion. However, that dose exceeds the emetic dose of 0.07 mg/kg/day andmay lead to vomiting in some cases. No severe illness or injury would be expected. Noevidence exists that people or animals exposed orally to cadmium have an increased incidence ofcancer.


Chromium, a naturally occurring element found in animals, plants, rocks, and soil and involcanic dust and gases, was found in surface water, sludge, and soil on site. Chromium exists inthree forms: chromium (II), chromium (III), and chromium (IV) Chromium (III) compounds arestable 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 thepresence of oxidizable organic matter.

Inhaling or ingesting small amounts of chromium will not cause illness or injury. ATSDR doesnot 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 ofchromium (III) at 1.00 mg/kg/day (28). An RfD is an estimate of the daily human exposure to acontaminant, 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 inindividuals who are chromium sensitive. Those individuals may have dermatitis or skin irritationand inflammation. Chromium sensitivity, which is uncommon, usually develops after prolongedcontact.


Copper, a reddish metal that occurs naturally in rock, soil, water, sediment, and air, as well as inplants and animals, is an essential element for all known living organisms including people andother animals. Food naturally contains copper. An individual typically will ingest about 1mgcopper a day through normal eating and drinking. Children at NHPC were exposed to copper insurface water and sludge on the site. ATSDR does not have MRLs for copper, and EPA has noRfD for its ingestion. Children playing in surface water and sludge at NHPC should notexperience severe health effects as a result of their copper exposure. Minor health effects thatcould occur following infrequent exposure to copper include diarrhea, abdominal pain, andvomiting (29).


Lead, a naturally occurring bluish-gray metal found in small amounts in the earth's crust, wasfound in sludge and soils at NHPC. Lead exposure is particularly dangerous for unborn childrenand young children because they are more sensitive to it during their development (25). TheAmerican Academy of Pediatrics considers lead a significant hazard to the health of children inthe United States (30). The Centers for Disease Control (CDC) guidance on blood lead levels inchildren is 10 g/dl. ATSDR has no MRL, and EPA has no RfD for lead. Blood lead levels werenot measured in children who played on the site. However, estimates of blood lead levels forchildren 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 adversehealth effects (44).


Nickel, a hard, silvery white metal with no characteristic odor or taste, has properties that make itdesirable for combining with other metals to form mixtures called alloys. Nickel is frequentlyalloyed with iron, copper, chromium and zinc (31). Rivers and lakes normally have lowconcentrations of nickel. Children at the site were exposed to nickel in surface water and sludgein lagoon areas at the site. Children could have been exposed to nickel in soil at the site bygetting it on their skin or by eating it in dirt.

ATSDR does not have MRLs for nickel; they will be derived when sensitive endpoints (targetorgans) can be established. EPA does have an RfD for nickel (soluble salts) ingestion. Theestimated doses of nickel to which children at the site were exposed do not exceed the RfD. Skincontact may cause red, irritated skin. Studies have shown that inhalation of nickel refinery dustand nickel subsulfide may cause cancer. No human or animal studies indicate that nickelingestion can cause cancer. Children playing on the site are not expected to become ill or injuredas a result of nickel exposure.


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 associatedwith harmful effects. Too much exposure to tin compounds can cause stomachaches, bloodchanges, liver and kidney effects, and skin and eye irritation (32). Children playing at NHPC wereexposed to tin in surface water and sludge on site. No specific populations unusually susceptibleto health effects of inorganic tin compounds have been identified. ATSDR does not have MRLsfor tin. EPA's RfD for tin ingestion is 0.62 mg/kg/day (32). The estimated doses of the children'stin exposure were well below the RfD; therefore, illness or injury are not expected.


Zinc, one of the most abundant trace metals in humans, is found in all tissues and tissue fluidsand is part of many enzyme systems (33). Children were exposed to zinc at NHPC in surfacewater, dried sludge, and soil on site. The children's estimated exposure to zinc in the lagoonsludge was lower than the RfD comparison values for ingestion of zinc. Therefore, no illness orinjury 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 othersubstances in the presence of zinc was not found (33).


Cyanides are compounds composed of a common structure, which is formed when elementalnitrogen and carbon are combined. They are produced by certain bacteria, fungi, and algae andare found in many foods and plants. Of the cyanide compounds, hydrogen cyanide, sodiumcyanide, and potassium cyanide are those most likely to be found in the environment as a resultof 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 shorttime 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 theexact half-life of cyanide in water is not known, it is believed to be short (24). Most cyanides inwater form hydrogen cyanide and evaporate. Some cyanides in water are transformed into lessharmful chemicals by microorganisms in the water or by forming a complex with metals, such asiron. ATSDR does not have MRLs for cyanide ingestion. The estimated dose of cyanide towhich children playing on the site were exposed does not exceed the chronic oral RfD of 0.02mg/kg/day. No data indicate that cyanides are carcinogenic. EPA has assigned cyanide a Dclassification, i.e., it is not possible to determine the potential of cyanide to cause cancer inpeople. The children's ingestion of cyanide at the estimated dose is not expected to cause illnessor injury.

Carbon Tetrachloride (CCL4)

CCL4, a clear, heavy liquid with a sweet odor, evaporates readily; therefore, CCl4 is not oftenfound in liquid form in the environment. Most CCl4 is found as a gas in the atmosphere. Smallamounts also are found dissolved in water. In air, CCL4 concentrations of 0.1 ppb are commonaround the world; higher concentrations (0.2 to 0.6 ppb) are found in cities (35). Children at theNHPC 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 MRLis 0.007 mg/kg/day (35). ATSDR does not have a chronic MRL; EPA's RfD is 0.0007mg/kg/day. The estimated dose of children who contacted surface water containing CCl4 doesnot exceed either the MRLs or the RfD. Hence, no non-carcinogenic adverse health effects areexpected 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, theestimated exposure to this compound is expected to result in a negligible increase in carcinogenicrisk.

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

1,2-DCE, a clear, synthetic liquid not found naturally in the environment, evaporates at roomtemperature; it has a pleasant smell and sweet taste. Small amounts of 1,2-DCE released intowater 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 improperdisposal 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 MRLis 0.005 mg/kg/day (36). The estimated dose of 1,2-DCE to which people may have been exposedin surface water was less than the acute MRL. Neither illness or injury is expected followingacute 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, orexist dissolved in water and other chemicals. It also may exist as a liquid in soil and as a vaporin air. 1,1,1-TCA has a sweet yet sharp odor. Animal studies have not shown that 1,1,1-TCA inthe 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 couldbe harmful to humans. EPA has assigned 1,1,1-TCA a carcinogenic classification of D, i.e., itcannot 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 surfacewater 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 tocause illness or injury.

Trichloroethene (TCE)

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

Table 14.

Comparison of Estimated Exposure Dose of Children Playing on Site to Health Guidelines
ContaminantExposurePathwayHealth Guideline for Ingestion (mg/kg/day)
ValueSourceExceeded byEstimatedExposure Dose?
CadmiumLagoon SurfaceWater0.0007Chronic OralMRLNo
Cadmium Sludge0.0007Chronic OralMRLYes
CadmiumSurface Soil0.0007Chronic OralMRLNo
Chromium (VI)Surface Water0.005Chronic Oral
Chromium-TotalSurface Water 0.005/ 1.00Chronic Oral
Chromium TotalSludge0.005/ 1.00Chronic Oral
Chromium TotalSoil0.005/ 1.00Chronic Oral
LeadSludge depthunknownNANANA
Lead SludgeNANANA
NickelSurface Water0.02 Chronic Oral RfDNo
NickelSludge0.02Chronic Oral RfDNo
TinSurface Water0.62Oral RfDNo
Tin Sludge0.62Oral RfDNo
ZincSurface Water0.3Oral RfDNo
ZincSludge0.3Oral RfDNo
ZincSoil0.3Oral RfDNo
Cyanide Surface Water0.02Chronic OralRfDaNo
CyanideSludge0.02Chronic OralRfDaNo
CCl4Surface Water0.2
Acute MRL
Inter. MRL
1,2-DCESurface Water0.02Chronic Oral RfDNo
TCESurface Water0.7Inter. MRLNo

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 andcadmium during site remediation. Exposure was by way of inhalation.


As reported earlier in this public health assessment, cyanide was detected in ambient air threetimes at the day care center monitoring station; the maximum concentration measured was 0.026mg/m3. There are no MRLs for acute, intermediate, or chronic exposure to cyanide by way ofinhalation; similarly, EPA has no RfDs for cyanide. At least nine states, however, haveregulations and/or guidelines for acceptable ambient air concentrations of cyanide and itsderivatives (34). The amount of cyanide detected at the day care center is well below the lowestreported 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 thoseconcentrations could cause illness or injury.


Cadmium was also detected in ambient air at the day care monitoring station (maximumconcentration: 0.0003 mg/m3) (Table 15). Although the maximum concentration detectedexceeds the chronic MRL, cadmium was detected only once in the ambient air around the daycare center probably as a result of ongoing remedial activities at the time. Based on this data, noadverse health effects are anticipated to result from cadmium exposure of children at the AvantiDay Care Center.

Table 15.

Comparison of Estimated Exposure Doses of Children at the Day Care Center to Health Guidelines
ContaminantExposurePathwayHealth Guideline (mg/m3)
Ambient Air
Inhal. MRL
Cyanidea Off-site
Ambient Air

    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 dustand other small particles over an estimated 20 year period beginning in 1962. To estimateingestion exposure, it was assumed that the typical worker ingested about 200 mg of dust/dayduring 260 days of exposure over the course of a year. Indoor air monitoring data were notprovided to ATSDR; as a result, an estimated inhalation dose could not be calculated.


Workers who inhale cadmium for a long period (chronic inhalation) may have an increasedchance of developing lung cancer (27). The estimated exposure dose of adults working in thefacility exceeded ATSDR's chronic ingestion MRL of 0.0002 mg/kg/day. Since the estimatedexposures were high, those persons may have experienced (and may continue to experience)illness or injury, although none have been reported to ATSDR. Proteinuria, kidney tubuledysfunction, and reduced urine are some expected effects of exposure (27). Cigarette smokeexposes the general population to higher than average levels of cadmium. Smokers withoccupational exposure to cadmium are at highest risk for illness or injury. Although cadmium isclassified as a probable carcinogen when exposure is by way of inhalation, neither human noranimal studies provide sufficient evidence to determine whether cadmium causes cancer whenexposure is oral.


NHPC workers were exposed to chromium by ingesting dusts and other small particles at thefacility. More data are available on the effects of chronic inhalation exposure in people andanimals than there are on the effects of oral exposure. ATSDR was not provided with data onchromium concentrations in air inside NHPC. The respiratory system and the skin are theprimary 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 tochromium (III) and chromium (VI) compounds. This lack of toxicity may have been because ofthe poor absorption of chromium through the gastrointestinal tract. The estimated exposure doseof chromium of workers at the NHPC facility exceeded the chronic RfD for ingestion ofchromium (VI). However, exposure at the estimated doses is not expected to cause illness orinjury, except in chromium sensitive sub-populations. In that population, skin irritation isexpected. Chromium is classified as a human carcinogen, and occupational inhalation studiesindicate a correlation between long-term exposure to chromium (VI) compounds and lungcancer. Occupational studies generally are concerned with inhalation exposures. Cancer studieshave 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 wereexposed to chromium by way of inhalation. Lung cancer may occur long after exposure hasended. 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 highlevels of chromium in air. Occupational exposure to chromium (III) compounds may not be asgreat a concern as chromium (VI) exposure. Oral exposure to chromium is not believed to causecancer.


Workers were exposed to nickel inside the NHPC facility. Cancer of the lung and nasal sinus isthe 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 fromlung diseases in people who inhaled nickel while working (31). An increased rate of cancers of thelung and the nose were also observed in workers exposed to nickel. EPA classifies nickelrefinery dust and nickel subsulfide as Group A human carcinogens while nickel carbonyl isclassified as a Group B2 carcinogens.

ATSDR does not have MRLs for nickel ingestion. EPA's RfD (oral) for soluble nickelcompounds 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 healtheffects.


Workers at the NHPC facility also were exposed to tin by ingesting dust and other smallparticles. ATSDR does not have MRLs for tin ingestion. EPA's oral RfD for inorganic tin is0.62 mg/kg/day. The estimated exposure dose for workers at the NHPC facility was much lessthan that value, therefore, neither illness nor injury is expected.


Workers also were exposed to zinc inside the NHPC facility. No relationship between theoccurrence of cancer in humans and occupational exposure (primarily by way of inhalation) tozinc has been demonstrated (33). No data were available on respiratory effects in people oranimals following oral exposure to zinc or zinc compounds. Several studies have suggested thatingestion of zinc may cause symptoms of gastrointestinal distress or alterations ingastrointestinal 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 comparisonvalue 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
Contaminant Exposure
Health Guideline (mg/kg/day)
Value Source Exceeded by Estimated Exposure Dose?
Cadmium Dust/Small particles 0.004
Acute MRL
Chronic Oral MRL
Chromium Dust/Small particles 0.005 Chronic Oral MRL Yes
Zinc Dust/Small particles 0.3 Oral RfD No
Nickel Dust/Small particles 0.02 Chronic Oral
Tin Dust/Small particles 0.62 Oral RfD No

Recreators at Horseshoe Pond/Merrimack River

Sediment and Surface Water

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

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


Based on surface water and sediment sampling data, fish in the Horseshoe Pond and MerrimackRiver are not expected to bioaccumulate site related contaminants. However, it should be notedthat NHDPHS has issued a Fish Ingestion Advisory for Horseshoe Pond based on elevatedmercury levels in found in largemouth bass. The elevated mercury levels detected in HorseshoePond 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 to1,1-dichloroethane, 1,1-dichloroethene (DCE), 1,1,2,2-tetrachloroethane, 1,1,1-trichloroethanetetrachloroethene (PCE), and trichloromethane (chloroform) by way of inhalation, ingestionand/or dermal contact. Available MRLs and RfDs which are listed below for these VOCs werenot exceeded and thus no non-carcinogenic adverse health effects are anticipated to result fromthe use of this well.

Based on the March, 1990 sample of this private well, an ATSDR Health Consultation concludedthat no adverse health effects would result from use of this well. An additional sample taken inAugust, 1993 detected similar VOC contamination with some VOCs detected at higher levelsthan the previous sample. Although VOC levels detected in this more recent sampling are stillnot expected to result in non-carcinogenic adverse health effects, the continued presence ofmultiple 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 thatshowering use be minimized (43).

B. Health Outcome Data Evaluation

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

Table 17.

Comparison of Estimated Exposure Dose of Private Well Users to Health Guidelines
Health Guideline (mg/kg/day)
ValueSourceExceeded byEstimatedExposureDose?
1,1-dichloroethanePrivate WellNANANA
DCEPrivate Well0.20
Inter. MRL
Chronic MRL
1,1,2,2-TetrachloroethanePrivate WellNANANA
1,1,1-trichloroethanePrivate WellNANANA
PCEPrivate Well0.1
Inter. MRL
Oral RfD
chloroformPrivate Well0.01chronic MRLNo

NA = Not available

C. Community Health Concerns Evaluation

  1. Is it advisable to eat fish from, swim in, or use water for irrigation from HorseshoePond or the Merrimack River?

    It is likely that contaminated groundwater is discharging to Horseshoe Pond at the northbank adjacent to the YMCA property. In 1982, several surface water samples from thepond's northern bank contained elevated levels of cyanide and cadmium. Analysis ofrecent samples taken in a radial pattern around the pond did not find these or any other siterelated contaminants at levels of concern. Analysis of Merrimack River surface water andsediment samples were below detectable levels for site-related contaminants. Based on thismore recent sampling, contact with sediment and surface water near Horseshoe Pond or theMerrimack River does not represent a public health hazard.

    The U.S. Fish and Wildlife Service sampled fish from Horseshoe Pond at the request ofEPA. Fish tissue was analyzed for the presence of PCBs and several metals. Cadmiumwas not detected at levels of public health concern. Mercury, however, was detected atlevels 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 datawas 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 sourceof 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 ownedby the YMCA?
    Who will monitor the groundwater beneath the property for contamination?

    Using information obtained during evaluation of contaminant movement from the NHPCsite (Environmental Pathways Section), it is unlikely that there has been any appreciablecontamination of soil or ambient air with site-related contaminants. Soil and ambient airwould be the likely media to which children would be exposed if a ball-field was built onthe YMCA property. Groundwater beneath the YMCA property is contaminated because ofthe site; however, children or others playing on the proposed ball-field would not beexposed to those contaminants unless the contaminated groundwater beneath the propertyis to be used as a source of drinking water (i.e. drinking fountain). Municipal watersupplies 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 theYMCA 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 HealthOfficer receive a copy of the results?

    Any future sampling of groundwater monitoring wells at the site will likely be performedby EPA; therefore, this concern will be forwarded to them. The Merrimack Health Officershould contact the EPA Remedial Project Manager for the site to arrange to receivemonitoring results as they are available.

  4. If the contaminated materials are not removed for 10 years, is there something thatcan 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 publichealth assessment evaluates not only past and current public health concerns, but also thosethat may arise in the future. The conclusions and recommendations of this public healthassessment, 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 ofremoval and remedial actions?
    Yes, the air around the site was contaminated during removal and remedial actions. Duringthe excavation and treatment of soils and sludge material, ambient air samples werecollected. No detectable concentrations of organic vapors or hydrogen cyanide weredetected. 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 remedialactivities 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 timethe NHPC building was demolished and removed. This has eliminated the storage tank asa possible source of groundwater contamination except for any residual soils that werepreviously 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 thebuilding and the site in general to trespassers.

    Demolition and removal of the NHPC building began in early December, 1994 and wascompleted before the end of the month. The removal operation also included regradingand a temporary cover over the former building location to prevent rainwater infiltration ofthe 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 usingmunicipal and/or private well water?

    One off-site well on Daniel-Webster Highway which has been sampled twice has shownlow levels of VOC contamination. Levels of VOCs in this well are below regulatoryguidelines 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 hasprompted NH DPHS to recommend that this well not be used for drinking purposes. Moresampling of this well is needed to update this analysis.

    ATSDR believes that no private domestic wells drawing water from the overburden aquiferare affected by contaminants migrating from the site in groundwater. Because of the lackof information on the extent of contamination and direction of groundwater flow in thebedrock aquifer, however, it cannot be determined if the NHPC site is affecting the qualityof water in private wells that draw from that aquifer. It is believed that people using waterfrom MVWD are being supplied drinking water of acceptable quality.

    A well survey is not needed because private wells in the area served by MVWD wereidentified in 1990 for the ATSDR Site Summary Report (7). Furthermore, information fromthe Merrimack Health Officer indicates that private wells probably would not be installedin the contaminated plume area west of the Merrimack River because municipal watersupplies are available (9).

  9. Are other sources of contamination near the NHPC site contributing to theproblem? Are those sources contributing to contamination of the Merrimack River?

    Evaluations performed at several industries and commercial properties near the NHPC siteindicate it is likely that other sources of contamination exist. Furthermore, numerousindustries and commercial enterprises are adjacent to NHPC and the Merrimack River, aswell as up- and downstream from the site. Therefore, it is likely that other sources arecontaminating the Merrimack River.

  10. Is the contamination of Lagoon #5 a health concern; should the area be fenced toprevent access?

    Lagoon #5 is also known as the undefined wetland north of Lagoon #3. Severalcontaminants have been detected in soils from the undefined wetland at concentrations ofpublic health concern. Children could have been exposed to contaminants found in theundefined wetland from the 1960s through 1987-1989. The site perimeter fence, built in1991, encloses Lagoon #5 and, therefore, limits exposure to those contaminants.

  11. How stable is and what is the life-expectancy of the liner covering thecontaminated soil in the on-site holding cell?

    Because the liner was installed and will be maintained by EPA, this concern has beenforwarded 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 siteperimeter 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 haveaccumulated in the raspberry plants outside the site perimeter fence. Therefore, raspberriesfrom those plants were probably safe to eat.

  13. What is the public health impact of residential gardening in areas adjacent to thesite?

    Our evaluation of the possible routes of contaminant migration (environmental pathways)from the NHPC site indicate it is highly unlikely that appreciable site contaminants havemigrated 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 onthose gardens. As a result, vegetables or fruits from those gardens are probably safe to eat.

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