PUBLIC HEALTH ASSESSMENT
GROVELAND, ESSEX COUNTY, MASSACHUSETTS
The presence of hazardous contamination on the site is not necessarily indicative that actual exposure to site-related contaminants is ongoing. Detected contamination levels are reported in this section and compared with specific health reference values (eg. MCLs, EMEGs). These comparison values represent those levels below which no adverse health effects (other than cancer) has been identified or those levels to which exposure has been associated with a cancer risk of less than one in one million. Contaminants of concern are those that were detected at levels above comparison values. The health risks of such exposure are evaluated in subsequent sections of this public health assessment. Some contamination levels detected did not exceed their respective comparison (or guidance) values. These levels are reported for the sake of completeness and to preserve historical perspective.
The data tables in this section include the following acronyms:
- VOC-Volatile Organic Compounds
Vinyl Cl-Vinyl Chloride
HML-Haverhill Municipal Landfill
MCL-Maximum Contaminant Level
EMEG-Environmental Media Evaluation Guides
ug/l-micrograms per liter
ug/kg-micrograms per kilogram
TCE belongs to a class of chemicals known as Volatile Organic Compounds (VOCs). The VOC contamination levels that were detected prior to the shutdown of the municipal wells are presented in Table 1. No other VOC contamination was detected. The TCE levels detected in waters drawn directly from the Station 1 municipal well in May of 1979 were not appreciably different from those detected in waters drawn from a faucet at the Groveland Town Hall during the same time frame9,10. As shown in Table 2, virtually no TCE was detected in municipal waters drawn directly from the station 1 well after August of 19871.
Table 3 presents historical data of ground water monitoring conducted in the immediate vicinity of the Valley factory. Historically, the highest TCE levels were detected in ground water immediately beneath the southern end of the factory and also at a point 50 feet east of the factory. TCE levels were also elevated in ground water immediately above the bedrock surface 100 feet north of the factory. The contamination levels in this well appeared to have subsided. As presented in Table 4, 11,000 micrograms per liter (ug/l) of TCE were detected in this well when monitored in 1990.
Trichloroethylene and 1,2-DCE are currently the predominant VOC contaminants in the vicinity of the Mill Pond and the Valley plant area. Table 4 also shows that currently the highest TCE contamination levels are detected at or underneath the bedrock surface. TCE levels greater than 1,000 ug/l were detected in ground water as far as 1,690 feet north of the Valley factory. Further north, TCE levels decrease sharply in both deep overburden and bedrock ground water and TCE levels exceeded 100 ug/l in only one well. Waters drawn from one monitoring well screened in the deep overburden immediately south of the Station 2 municipal well contained TCE levels of 150 ug/l1.
Generally, ground water monitored near the top of the water table had considerably less TCE contamination than did ground water at or below the bedrock surface. TCE levels detected at or near the water table level did, however, exceed those considered to be safe.
The contour and location of the ground water plume containing TCE contamination levels of 100 ug/l or greater, as determined from monitoring conducted in 19901, did not differ significantly from that which was derived from the monitoring conducted prior to 19852. Based on the monitoring conducted in 1990, the contamination plume containing TCE levels of 5 ug/l or greater extends 3,900 feet north of the Valley plant, along Johnson Creek to the Merrimac River (see Figure 2). At the Valley plant, the plume is 350 feet in width and widens to 1,300 feet near the Station 2 municipal well.
As presented in Table 4, TCE and 1,2-DCE were the predominant contaminants emanating from the Valley plant. Significant levels of other VOC contamination were seldom detected within these plume waters that were external to the Valley site. Shallow bedrock waters monitored 300 feet north of Mill Pond contained 6 ug/l of PCE.
VOC contamination was detected away from the TCE contamination plume and the levels detected are presented in Table 5. VOC contamination was detected in monitoring wells on the Chesterton property however it does not appear to be migrating since none of these contaminants were detected immediately downgradient of the property1. PCE contamination was detected in ground water southeast of the Haverhill Municipal Landfill(HML). TCE levels have been detected in one well near Station 2 downgradient of the landfill. No TCE levels, however, have been detected in wells drilled between the landfill and Station 2. The landfill is a separate NPL site and the contamination associated with this site will be addressed in a forthcoming public health assessment.
Heavy metal contamination was detected sporadically throughout the site. There were no evident trends of metal contamination migration with the possible exception of that evidenced in the wells close to the Haverhill Municipal Landfill. The analyses for metals were conducted on both unfiltered and filtered ground water samples. In all but one instance, metal concentrations of filtered samples were significantly reduced indicating the possibility that metal contamination is not dissolved in ground water but bound to suspended sediment in the ground water sample. As presented in Table 6, the background concentrations of metals, which were monitored in unfiltered off-site waters drawn from a monitoring well south of Salem Street approached or exceeded safe drinking water standards1.
Elevated metal levels were detected in ground water 300 feet downgradient of the Station 1 municipal well. It is important to note, however, that unsafe metal levels were not detected in waters drawn from the Station 1 well or those wells immediately upgradient to the Station 1 well when this monitoring was conducted in 1990.
From 1978 through 1990, MDEP monitored municipal waters drawn from a tap at the Groveland Town Hall for metal contamination. Monitoring was conducted seven times during this period and arsenic levels ranged from ND to 2 ug/l. Lead levels ranged from ND to 4 ug/l. The maximum lead and arsenic levels were below the MCLs of 50 ug/l established for both of these metals.
Monitoring for VOC and metal contamination was conducted on waters drawn from one private well known to be drilled within site boundaries. Trichloroethylene (4.5 ug/l) was detected in these waters which were sampled in July of 1991. No elevated metal levels were detected.
Surface water samples recovered from Mill Pond in 1982 contained TCE and 1,1,1-TCA levels of 3,200 and 3,400 ug/l respectively. When these waters where monitored one year later, however, 1,1,1-TCA levels subsided to trace detection levels. It is possible that these contaminants either evaporated or were diluted. In 1984, water samples were recovered from a stagnant mill race, downstream from Mill Pond and TCE (763 ug/l) as well as 1,2-DCE (160 ug/l) were detected. No mention is made of subsequent monitoring in this area2.
Surface waters and sediments were monitored again in 1990. The results of this investigation are presented in Table 7. No other appreciable levels of VOCs were detected in waters either upstream or downstream of these areas where VOC contamination was detected during the monitoring conducted in 1990. The metal levels detected in stream waters flowing through the site did not approach those that would be of health concern. In addition, no elevated VOC or metal levels were detected during monitoring of site-associated stream sediments1.
No soil monitoring was conducted on the site in 1990, however, extensive soil monitoring was compiled at the Valley site in 1984. The results of this investigation are presented in Table 8. These contaminants were also detected in ground water monitored at the Valley Plant in 1984.
To date, no air monitoring has been conducted on the site.
No fish have been sampled from site associated surface waters for food chain contamination monitoring.
Given the extensive monitoring and the vast area within the site, no off-site monitoring was conducted.
The conclusions presented in this public health assessment are based on the data reviewed. The validity of the conclusions is dependent on the quality of the data provided.
No risk of site-related injury was observed during the site visit conducted in April of 1992.
To identify possible facilities that could contribute to the air,
surface water and soil contamination at the Groveland Wells site,
the Toxic Release Inventory (TRI) data base was searched. TRI is
developed by the USEPA from the chemical release information
provided by certain industries. No off-site releases of
contaminants were reported. A summary of contaminants released to
air by on-site industries are presented in Table 9.
In this section, various transport means of environmental hazards from the contamination source to human receptor populations are presented. If such migration and uptake by some members of the population is believed to occur, the environmental pathway is considered to be complete. Complete exposure pathways are summarized in Table 10. The presence of a complete environmental pathway, however, does not necessarily mean that hazardous exposure has occurred or is ongoing. Potential pathways are those which may have been completed in the past or may become complete in the future. Exposure indicated by these pathways, however, is not currently believed to be ongoing. These pathways are identified in Table 11. Estimates of the number of exposed persons for completed pathways and the number of potentially exposed persons for potential exposure pathways is presented in Table 12.
The extent of public health risk depends not only on the presence of exposure but also on the toxicity of the contaminants and the dosages to which the receptor population is exposed. These two factors are discussed in the Public Health Implications section.
Residents from Groveland and West Newbury were probably exposed to TCE-contaminated municipal water prior to the shutdown of the two existing municipal wells in 19799,10. At that time the municipal well at Station 1 was the primary water source. Station 2 was used on an intermittent basis to supplement the water needs of the two communities during the summer months. Water from these wells was pumped to a holding tank and from there it was distributed to the residences and businesses of both Groveland and West Newbury12. It is unlikely that TCE contamination detected in the municipal wells evaporated from the holding tank or was dissipated through the distribution system since TCE levels detected in waters drawn from a faucet at the Groveland Town Hall in 1979 were nearly the same as those detected in waters drawn directly from the municipal well at Station 1 at the same time (Table 1). These wells were used from 1965 to 1979 and ingestion of TCE probably occurred at some point during this time. Inhalation and dermal absorption of TCE likely occurred during bathing activities within this time frame as well.
The exact dose and duration of this exposure can not be currently determined with any degree of certainty. Low levels of TCE were detected in waters drawn from a faucet at the Groveland Town Hall and increased nearly tenfold within a year. It can not currently be established, however, that the low levels detected in 1978 were indicative of advancing TCE contamination and that prior to that point in time, ground waters drawn from the municipal wells contained less than 13 ug/l, the levels detected at the town hall in 1978. In order to substantiate this assertion, it would have been necessary to have conducted extensive monitoring of ground water in the area at that time.
Environmental monitoring and hydrogeological investigations were conducted between 1981 and 1991. These studies identified migratory pathways of TCE through ground water towards the municipal wells. Historical data presented in Table 3 demonstrate that the highest TCE levels were detected in ground water at or near the vicinity of the Valley factory. In 1990, the highest TCE levels detected off the Valley property were in ground water at or below the bedrock surface. Since TCE is heavier than water and in this area does not appear to be adhering to soils to a significant extent, it is thought that contamination may have migrated downward through the subsurface soils on the Valley property towards the bedrock surface1. It is also possible that this contamination may have migrated in a non-dissolved state and settled at the bedrock surface and in fissures beneath the bedrock surface. The contamination has, over time, dispersed into ground water and migrated northward along and under the bedrock surface1. This is evidenced by the data presented in Table 4 and in Figure 2, which presents TCE contamination contours.
TCE contamination migration through ground water may be impacted by the soil composition in the area. Hydrogeological studies have shown that generally, deposits near the bedrock surface are more coarse and more conductive to water flow and soils near the land surface which are finer grained and ground water flow is slower at this level1. This may help to explain the presence of TCE contamination at lower depths, and the relative absence of TCE in waters near the top of the water table, away from the Valley site.
Hydraulic gradients, or areas of ground water elevations and depressions, influence the direction of ground water flow and consequent TCE contamination. Natural ground water flow in the aquifer is towards the Merrimac River to the north. This major water body ultimately receives the surface and ground water from northeastern Massachusetts and southern New Hampshire. Hydraulic gradients in the aquifer are such that ground waters migrate from east and west towards the center of the aquifer which slopes downward towards the Merrimac. Environmental monitoring has shown that the migration of TCE contamination is oriented towards Mill Pond from the Valley plant. After this point the direction of contamination flow is heavily influenced by the direction of ground water flow which in this area is aligned with that of Johnson Creek flowing northward toward the Merrimac1,2.
The operation of the municipal wells prior to their shutdown may have affected the lateral migration patterns of TCE in ground water. TCE levels of 118.8 ug/l were detected in the well at Station 1 when it was shut down in 1979. At that time TCE levels in Station 2 were 10.8 ug/l. During this period the Station 2 well was being used only on an intermittent basis to supplement the production from the well at Station 1. As a result of the shutdown of the well at Station 1, the well at Station 2 was used on a regular basis. Five months later, TCE levels of 108.7 ug/l were detected in Station 2. It is possible that the direction of TCE contamination movement was northeasterly as a result of the operation of the well at Station 1. When the first municipal well shutdown and the Station 2 well increased its output, the direction of the TCE contamination plume may have shifted northward1.
The impact of the operation of the on-site municipal wells on local ground water flow was also demonstrated in the pump tests conducted for the USEPA in 1990. After continual pumping of the Station 1 well for 11 days at a steady rate of 400 gallons per minute, decreases in the ground water levels were observed as far as 2,000 feet southwest towards Mill Pond. Decreases in water levels were also observed 1,100 feet eastward and northward. These drawdowns, or localized depressions in ground water levels, in turn cause the migration of ground water from higher water table elevations toward the well. VOC levels were monitored in nearby wells before and after the pump test. Although no VOC contamination was detected in waters drawn from Station 1 either at the beginning or end of this test, there was a small increase in TCE levels at the end of the test which were detected in nearby monitoring wells west of station 1.
Since the municipal well at Station 1 was restored in 1987, the MDEP has been regularly monitoring the waters drawn from this well for VOC contamination. Virtually no VOC contamination has been detected in this well since a malfunction of the filtration unit was repaired in 1987. In addition, although metals have been detected throughout the site, no metal levels above those which are considered safe have been detected in municipal waters drawn from the well at station 1. It is not possible to determine whether Groveland and West Newbury residents were exposed to heavy metal contamination prior to 1978 since no monitoring for these contaminants was conducted during this time frame.
Municipal waters drawn from a tap at the Groveland Town Hall were monitored for metal contamination seven times from 1978 to 1990. During this period, arsenic was detected twice and lead was detected once. Since these contaminants were not consistently detected and a source of metal contamination has not yet been identified, a mechanism for metal migration can not be established. In addition to ground water contamination, it is possible that lead could also be detected as a result of it leaching from the plumbing within the building from where the waters were drawn. Chronic exposure to arsenic and lead is not likely to be ongoing since these metals have not been consistently detected in municipal waters drawn by MDEP.
As previously stated, monitoring of waters drawn the Groveland municipal well at Station 1 indicate that TCE exposure via ingestion, inhalation or dermal absorption is not currently ongoing. In addition, since the third Groveland municipal well was drilled in another aquifer distant to those at Stations 1 and 2, it is not likely that site associated TCE contamination has infiltrated these waters. All waters drawn for municipal wells throughout the Commonwealth are continued to be monitored for VOCs and metals to ensure their safety.
It is reported that one private well exists in the northern section of the site and waters from this well are used for bathing and laundering purposes only. Since TCE was detected in waters drawn from this well some degree of exposure via skin contact and/or inhalation is ongoing13. Exposure to metals is not ongoing at this residence since no hazardous heavy metal levels were detected in these waters.
The possibility of future ingestion, inhalation or dermal absorption of contaminants detected in the aquifer in the absence of appropriate remediation, can not currently be dismissed. As previously stated, ground water and TCE contamination migrate toward the Merrimac River. External factors that cause localized lowering of ground water levels such as the pumping of the municipal wells at Stations 1 and 2 can create hydraulic gradients which in turn can shift the direction of contamination migration towards these wells. Continual use of the Station 1 well similar to that in 1979 may once again draw TCE contamination towards it1.
Land usage in the area can also alter local ground water and contamination patterns by affecting the rate of precipitation permeation into ground. Sand and gravel pits are predominant in the aquifer region and no vegetative ground cover is likely to be present in areas where active mining is ongoing. As a result, precipitation will more readily permeate subsurface soils and elevate ground water levels in these areas. As these mining operations shut down in time, ground cover in the area will be restored and precipitation infiltration will be reduced, possibly altering the direction of local ground water flow1.
Exposure to other VOC contamination may be possible in the future since TCE is undergoing breakdown by microbial organisms in subsurface soils. This is evidenced by the detection of 1,2-DCE, a breakdown product of TCE, in the majority of ground water samples that contained TCE. It is not likely that 1,2-DCE co-migrated with TCE from the Valley site since the two compounds have different chemical properties such as water solubilities and soil adhesion tendencies which affect their environmental mobility in ground water. It is possible that TCE will undergo further breakdown to vinyl chloride, a known human carcinogen14, which has been detected in small amounts in ground water at the Valley factory.
In the absence of effective TCE removal from the aquifer in which the Station 1 and 2 municipal wells are situated, the future direction of TCE migration can not be predicted given the uncertainties discussed above. The USEPA has proposed remediation to ensure the future safety of the waters at the Station 1 municipal well which includes the construction of several ground water extraction wells to be placed throughout the aquifer. Waters will be pumped to units which will degrade TCE by treatment with ultraviolet light and an oxidizing agent15. It is anticipated that by implementing this remedial alternative, safe TCE levels will be attained within 30 years. The breakdown products of the photolysis/chemical degradation process include carbon dioxide, water and extremely dilute levels of hydrochloric acid16. Hazardous exposure to these breakdown products is not likely.
It is not currently possible to determine whether exposure to ground water metal contamination will occur in the future since no source nor transport mechanism for these elements can currently be determined. Arsenic and lead, naturally occurring elements, have been detected intermittently in on-site ground water as well as in those waters monitored upgradient to the site. They also were detected in monitoring wells downgradient of the Station 1 municipal well, but were not detected in the Station 1 well itself.
The reduction of metal levels after filtration may indicate that metals may not be migrating in solution with ground water but may be bound to soils suspended in ground water. There is disagreement among environmental scientists on the interpretation of filtered versus non-filtered ground water monitoring results. Since no unnatural source of arsenic or lead has yet been identified and the transport mechanism of these metals is still uncertain, the possibility of future arsenic or lead migration toward the Station 1 municipal well can not be determined.
Ground water removed from extraction wells during the TCE remediation process will be treated with agents which cause the precipitation of ground water metals. These waters will then be filtered to remove the metal contaminants. It is reported that VOC and metal levels in regional ground waters will be periodically monitored in order to ascertain that the operation of these wells is not drawing contaminants towards Station 115.
Currently two extraction wells are operating at the northern end of Mill Pond where the bedrock contour drops off sharply and ground water TCE contamination levels are elevated. The operation of these wells appears to have decreased TCE contamination levels in nearby waters above the bedrock surface. TCE levels in ground water monitored from a bedrock well drilled in close proximity to the extraction wells, however, continues to remain consistently high. It may be possible that contaminated ground water in bedrock cannot be accessed from overburden ground water at this point. It is not currently certain whether these wells will be used by EPA in the planned remediation.
It is anticipated that the treatment system will not completely remove TCE and that the effluent from the system will contain low but detectable levels of VOCs. It is planned that this effluent will be discharged to Johnson Creek. This is also currently being done at the Mill Pond extraction point. The stream waters which accept the effluent from this plant, had the highest VOC levels detected on the site, however, the discharge levels were within those permissible by the National Pollutants Discharge Elimination System (NPDES)1. It is anticipated that waters discharging from the proposed ultraviolet light/oxidation system will contain lower TCE levels than those currently draining from the air stripping unit at Johnson Pond. No appreciable VOC levels were detected immediately downstream of this discharge point.
Stream waters also do not exhibit appreciable levels of VOCs in stream areas were ground water is expected to discharge. It is possible that dermal exposure and incidental ingestion of surface water contamination could occur during wading activities. It is uncertain, however, whether these activities are actually ongoing. In addition, the surface waters north of Mill Pond where TCE contamination was detected were discolored and did not appear conducive to ingestion. Waters emanating from the PVC pipe from the extraction plant did not exhibit this discoloration and could possibly be mistaken for a spring outlet. No evidence of consumption of these waters was noted on the site visit conducted in April of 1992.
The extracted waters at Mill Pond are also pumped to an air stripping tower. Emissions from this air stripping tower, however, are not currently filtered and no air monitoring has been conducted in the area. The nearest residence is 350 yards northwest of this air stripping tower. It is then uncertain as to whether or not nearby residents are being exposed to emissions from the system.
Emissions of 1,1,1-TCA and PCE have also been reported at the A.W. Chesterton Company. It is also not certain whether a completed exposure pathway exists in this are since no air monitoring has been conducted in this area. Given the past use of VOC at the Valley plant and their detection in soils underneath the factory, it is possible that these compounds could be volatilizing into indoor air at the factory. In the absence of indoor air monitoring at the factory, it is not possible to determine whether exposure via inhalation is occurring.
As previously stated, streams within the site boundaries were
stocked with fish in the early 1950s2. It is not certain whether
fishing activities are still ongoing. VOCs are known to accumulate
in aquatic organisms but only to a limited extent. Since it is not
certain whether fishing is ongoing in the one area where elevated
TCE levels were detected and actual TCE contamination levels in
edible fresh water organisms were not monitored, it is not
currently possible to ascertain whether ingestion of fish harvested
from Johnson Creek constitutes a completed exposure pathway.
In this section the potential health risks posed to the public as a result of possible exposure to site contaminants are evaluated. In addition, available health data pertinent to the site are presented. The possible impact of environmental exposure on disease rates is discussed in this section. Finally, citizen concerns specifically voiced to public health officials are addressed.
Exposure to hazardous compounds detected in site-related environmental media at the Groveland site could precipitate disorders of the liver, kidney, circulatory system and nervous system. It must be emphasized, however, that hazardous exposure to on-site contaminants is not currently occurring. Each environmental pathway and its human health implications are discussed below.
1a. Ground Water Ingestion
Animal and/or human studies have demonstrated an effect on liver, kidney and central nervous system (CNS) function caused by ingestion of TCE17. Regular ingestion of maximum TCE levels (50,000 ug/l) detected in one well monitored in 1990 at the Valley factory, would precipitate liver and kidney dysfunction. Since these waters are not known to be consumed, it is extremely unlikely that acute liver and kidney disease resulting from TCE ingestion is a significant health concern associated with the site.
No substantial human evidence exists, to date, associating TCE ingestion with an increased incidence of adverse reproductive outcomes. One study did observe an elevated rate of congenital anomalies in a Massachusetts community whose drinking water was contaminated with numerous chlorinated hydrocarbons17. This study, however, had numerous methodological limitations, and as a result, cannot be considered conclusive. In 1988, the Woburn Environment and Birth Study (WEBS) began to extensively investigate the association between exposure to these ground water contaminants and risk of adverse reproductive outcomes. The findings of this study may lend a better understanding of the impact of exposure to chlorinated hydrocarbons on reproductive outcome. Ingestion of TCE in animal studies did demonstrate an association between TCE ingestion and decreased litter size17.
Although investigations of TCE exposure in humans, to date, have failed to present conclusive evidence of carcinogenicity, animal studies have associated TCE exposure with an increased risk of liver and kidney cancer. It is unlikely that humans would be environmentally exposed to the TCE levels that were necessary to induce cancer in laboratory animals. Nonetheless, it is possible that a small but finite number of liver or kidney cancers could develop in humans as a result of low level TCE exposure. To protect human health, a maximum contaminant level (MCL) for TCE in ground water has been established based on the suspected carcinogenicity of this compound. The MCL is founded on estimations of the human cancer risk resulting from a lifetime (i.e., 70 years) of low level TCE exposure which is in turn derived from animal study findings.
The TCE levels detected in the Groveland municipal water in 1979 exceeded the MCL for TCE. It is unlikely, however, that Groveland residents were exposed to these levels for seventy years. It may be possible that the residents of Groveland and West Newbury were not exposed to TCE for a long enough duration such that cancer incidence rates in these towns would be impacted. Currently, unsafe exposure to TCE via ingestion of municipal well water is not occurring.
Based on animal studies, ingestion of 1,2-DCE at levels detected in ground water on the site is associated with a reduction in red blood cell count. This risk, however, assumes regular ingestion for an extended period18. Currently, this scenario is not likely, since no drinking water wells are known to exist in those areas where elevated 1,2-DCE levels were detected.
Ingestion of arsenic levels detected in on-site ground water has been associated with an increased risk of kidney and liver disease, as well as with the development of vascular and skin lesions, gastrointestinal irritations, anemia and neuropathy. The severity of these effects increase with prolonged ingestion19. Exposure to arsenic levels that have been associated with these adverse health effects is not occurring via ingestion of municipal waters.
Chronic ingestion of arsenic contamination has also been associated with an increased risk of skin cancer development19. Arsenic has not been detected in monitored water drawn from the municipal wells. From 1978 to 1990 municipal waters drawn from a tap at the Groveland Town Hall were monitored seven times for metal contamination. Low arsenic levels were detected twice during this period. Chronic arsenic exposure via ingestion of municipal waters is therefore not likely to be occurring. In addition, no known use of ground waters is occurring from those wells where arsenic was detected.
Exposure to 1,1,1-TCA was believed to be associated with an increased risk of adverse reproductive outcomes20,21. 1,1,1-TCA was detected in municipal drinking water in Santa Clara County, California which served census tracts where increased rates of adverse pregnancy outcomes were observed. This concern diminished when the water distribution patterns were considered and it was determined that the areas receiving contaminated drinking water did not correlate with those where the elevated rates of adverse reproductive outcomes where observed21. The likelihood of hazardous exposure to this compound at the Groveland site is diminished further when it is considered that the 1,1,1-TCA levels detected on the A.W. Chesterton property were markedly lower than those detected in Santa Clara. It should also be considered that there has been no established off-site migration of this compound at the Groveland site.
Ingestion of elevated lead levels detected in the aquifer is associated with adverse neurobehavioral effects in children and increased blood pressure in adult males22. This is significant when it is considered that lead, especially in children, is not rapidly excreted and can accumulate in various organs and is stored in bones and teeth. Blood lead levels which are responsible for neurotoxicity are maintained in equilibrium with body lead stores21. Elevated lead levels have not been detected, however, in municipal or private ground water that is currently known to be consumed.
In summary, exposure to elevated levels of TCE, 1,2-DCE, arsenic and lead could potentially impact the hepatic, renal, nervous and circulatory systems. It is highly improbable that hazardous exposure to these substances is ongoing at this time.
1b. Ground Water Vapor Inhalation
Volatilization of TCE in shower waters would result in human exposure via inhalation. It is difficult to ascertain the levels of such exposure. Noncancerous adverse health outcomes such CNS, liver and kidney disorders have been associated with inhalation of TCE levels in the parts per million range17. Considering the municipal ground water TCE contamination levels that were detected in the past, such exposure via inhalation is unlikely.
It is uncertain whether or not TCE inhalation may be associated with increased risk of cancer development. Based on animal studies, inhalation of TCE has been associated with increased bladder, nasopharyngeal and oropharyngeal cancer risk. Inhalation of TCE has also been associated with increased risk of non-Hodgkin's lymphoma17. Since it is not known to what extent Groveland and West Newbury residents were exposed to TCE via inhalation, it is not possible to determine whether or not an elevated cancer risk is associated with this route.
Vinyl chloride, which can be produced via anaerobic degradation of TCE, is a known human carcinogen. Studies of workers exposed to vinyl chloride have demonstrated an increased incidence of liver angiosarcoma14. Inhalation of vinyl chloride from ground water may be a future concern if the contamination in ground water is not remediated. The actual health effects associated with past TCE inhalation or vinyl chloride inhalation in the future can not be assessed since levels of exposure to these compounds can not be ascertained.
The air stripping unit at the Mill Pond extraction system is releasing TCE into ambient air since granulated activated carbon filtration is not being implemented. Plausible TCE emission levels have been derived from models considering extraction rates and efficiencies of the air stripping unit. Cancer risk was then derived by USEPA using air transport modeling. A low but finite excess cancer risk was determined when exposure scenarios pertinent to the site were considered1. Such scenarios included an ambient air exposure to these levels, 24 hours a day, every day over the course of a lifetime. TCE monitoring in ambient air near the air stripping unit may help to more accurately determine cancer risk via this exposure route.
3. Surface Waters and Sediments
Exposure to TCE contamination levels in the surface waters where water is discharged from the air stripping unit at Mill Pond is not associated with any known acute health hazards. These levels are associated with an elevated cancer risk if ingested over the course of a lifetime. There is no indication, however, that this is currently occurring. Contamination levels detected in site-related sediment did not approach those that would pose health concerns.
Although fish in streams and ponds associated with the site were not monitored, it is unlikely that they will contain hazardous contamination levels. Low contamination levels were detected in these waters. In addition, site-related contaminants are not known to accumulate in fresh water organisms to a significant extent.
Cancer incidence data from the Massachusetts Cancer Registry were reviewed for the period between 1982 and 1988. The observed number of cancer cases in Groveland and West Newbury were compared with those that would be expected in these municipalities based on the state-wide cancer experience. Comparisons were made in cancers from specific anatomical sites that would be of concern based on past exposure scenarios associated with the site.
No leukemia or kidney cancer cases were observed in Groveland during this time period nor were any liver cancer cases observed in West Newbury. Although lung cancer incidence in Groveland (10 observed and 17.4 expected) and West Newbury (8 observed and 11.4 expected) were lower than expected, these decreases were not statistically significant. When the observed number of cases of cancer for a specific anatomical site is fewer than five, it is not possible to calculate a stable rate for this disease. As a result, there were too few non-Hodgkin's lymphoma (Observed= 2, Expected= 3.7), liver (Observed= 2, Expected= 0.5), bladder (Observed= 4, Expected= 4.8) and laryngeal (Observed= 2, Expected= 1.9) cancer cases to determine whether the rates of these cancers were significantly elevated or diminished in Groveland. In addition, the number of leukemia (Observed= 3, Expected= 1.5), non-Hodgkin's lymphoma (Observed =1, Expected =2.4), kidney (Observed= 3, Expected= 1.6) and bladder (Observed= 4, Expected= 3.3) cancer cases in West Newbury were also too low to determine statistical significance.
While no birth defects registry exists at the MDPH, incidence of low birth weight (less than 2,500 grams) and infant deaths are recorded through the existing Registry of Vital Records and Statistics. Between 1977 and 1980 the towns of Groveland and West Newbury experienced three infant deaths of the 387 live births in the area or 7.8 infant deaths per 1,000 live births. The infant mortality for the state during this time period was 11.0 infant deaths per 1,000 live births. In 1985, there was one reported case of infant death in Groveland and none in West Newbury. The infant mortality rate for the two towns combined in 1985 was 8.7 infant deaths per 1,000 live births compared to 9.1 infant deaths per 1,000 live births for the entire state. See Table 13.
The incidence of low birth weight among infants born in West Newbury and Groveland between 1977 and 1980 was 28.4 per 1,000 live births. In 1985, the low birth weight incidence rate for Groveland and West Newbury combined was 43.5 per 1,000 live births. The low birth weight incidence rate for the entire state between 1977 and 1980 was 63.7 per 1,000 live births and 59.0 per 1,000 live births in 1985.
The High Risk Infant Identification Program within the Bureau of Parent, Child and Adolescent Health at the MDPH routinely reviews birth certificates which are coded for detectable birth anomalies prior to the infant's discharge from the hospital. Using the data from this program, it is possible to provide a crude estimate of the birth defects rate within a specific municipality and compare it to that for the entire state. Between 1977 and 1980, there were two children born in Groveland with congenital anomalies. No children born during this time period in West Newbury had any evident birth anomalies. The rate of birth anomalies per number of live births in Groveland and West Newbury between 1977 and 1980 was 5.2 cases per 1,000 live births compared with that of 9.6 cases per 1,000 births experienced by the entire state. In 1985, the incidence of congenital anomalies in Groveland and West Newbury was 17.1 (2 cases) per 1,000 live births. The rate of congenital anomalies for the entire state that year was 9.6 per 1,000 live births. It is not possible to evaluate the difference in these rates since the number of congenital anomaly cases born in Groveland and West Newbury were so small. As a result, the rates for these municipalities are somewhat unstable (ie. the presence or absence of another case would drastically affect the rate).
We have addressed each of the community health concerns as follows:
1) How long were the Groveland Wells at Stations 1 and 2 contaminated prior to detection?
The exact duration of this exposure can not be determined with any degree of certainty. The wells began operation in 1965 and consumption of contaminated waters ceased in 1979. Low levels of TCE were detected in waters drawn from a faucet at the Groveland Town Hall in 1978 and increased nearly tenfold within a year9,10. It can not be currently established, however, that the low levels detected in 1978 were indicative of advancing TCE contamination and that prior to that point in time, ground waters drawn from the municipal wells contained less than 13 ug/l, the levels detected at the town hall in 1978. In order to substantiate this assertion, it would have been necessary to have conducted extensive monitoring of ground water in the area at that time. More information regarding this issue is presented in the Completed Exposure Pathways Section under Ground Water Pathways-Past. According to officials at ATSDR, dose-reconstruction technology may be available in the future that would enable health officials to further address these concerns.
2) Is the Groveland municipal water currently safe to drink?
The Groveland municipal water is currently safe to drink. Since 1987, the MDEP has been monitoring all municipal wells in the Commonwealth for VOC contamination. Currently, there is no evident contamination of municipal drinking water. No unsafe TCE levels have been detected in waters drawn from the municipal well at Station 1 since 1987. Waters from the third Groveland municipal well, which is distant to those at Stations 1 and 2 are not hydrologically connected to the aquifer where TCE contaminated ground waters were detected.
3) Is there a birth defects registry in Massachusetts?
There is currently no formal birth defects registry in the Commonwealth. The MDPH agrees that access to such a registry would provide a more accurate determination of whether regional deviations in patterns of birth defects exist in certain areas of the Commonwealth. Such a registry would implement a verification scheme. In the absence of such a process, rates of birth defects can only be estimated. Staff from the Bureau of Parent, Child and Adolescent Health are currently seeking funding for this effort.
4) How can reliable rates of adverse reproductive outcomes be derived in Groveland since it is a small town? Is it possible to attribute one birth defect per year in a town this small to environmental exposure given statistical limitations?
Analysts at MDPH attempted to circumvent this problem in two ways. Mortality of infants with congenial defects or birth complications from the towns of Groveland and West Newbury combined were considered. This is because citizens from West Newbury were at equal risk of exposure to drinking water contaminants as the citizens from Groveland.
In addition, the number of infant deaths from both towns for numerous years were combined in order to increase the size of the sample which would in turn stabilize the rate for such occurrences. This would also decrease the probability that such a rate was random. Nevertheless, this process still yielded insufficient numbers to evaluate statistical significance.
5) Is there a registry for neurobehavioral disorders? Teachers at the Bagnall Elementary School have observed abnormal behavioral patterns in students who were born shortly after TCE was detected in the Groveland Wells. Could school health records be reviewed to ascertain if there may have been changes in the health profile of the student body over time?
There is no registry for neurobehavioral disorders. One of the objectives of the Public Health Assessment is to determine the need for further investigation into the prevalence of adverse health outcomes associated with exposure to site contaminants in a particular region. If it is determined that further study is necessary, MDPH in conjunction with ATSDR will evaluate (with citizen input) the type of investigation to be undertaken. At this juncture in the Public Health Assessment process, it is not possible to review school records for possible neurobehavioral problems.
Surveillance efforts of the National Exposure Registry may in time provide information pertaining to a possible association between adverse health effects and TCE exposure. The Agency for Toxic Substances and Disease Registry has created the registry to obtain voluntary information from individuals who have been exposed to environmental hazards associated with NPL sites. The Agency is in the process of identifying such individuals who have been exposed to TCE throughout the country. The inclusion of interested residents from Groveland who have been exposed to TCE-contaminated water would add to the knowledge of all possible adverse health effects resulting such exposure. The subregistry has, however, reached full capacity and therefore no new individuals can be presently enrolled. Health information and pertinent findings pertaining to this subregistry should be disseminated to the citizens from the Groveland and West Newbury communities. If adverse neurobehavioral effects are reported by TCE exposed residents throughout the country, an investigation of such an association would be appropriate and the experience of the Groveland community should be considered.
6. Are citizens at an increased cancer risk as a result of past exposure to TCE in the Groveland municipal water? Can data from the Massachusetts Cancer Registry be used to accurately assess environmental impact on cancer rates in Groveland? Wouldn't the cancer rates in Groveland be invalidly lowered since exposed residents may have moved out of Groveland as a result of the municipal water contamination and residence of cancer cases in the registry is recorded at the time of diagnosis (and not at exposure)?
The TCE levels detected in municipal ground water in Groveland exceeded standards established by federal and state regulatory agencies. These standards are based on the findings of animal studies whose results were used in the absence of human evidence. The possible impacts of TCE exposure relating to cancer risk are discussed on page 20. To reiterate, it is possible that exposure to TCE in municipal ground water did not occur over a lifetime which is an assumption upon which the estimate of cancer risk resulting from TCE exposure is based. In addition, there were no elevations of cancer incidence rates for those cancers that were evaluated for statistical significance.
An unfortunate shortfall using surveillance data such as that from the Cancer Registry is that it must be assumed that migration in and out of the impacted towns will not influence the number of cancer cases residing in Groveland at the time of their diagnosis. Given the possibility that some time must elapse between that when environmental exposure occurs and when the cancer is detected (ie. the latency period), it is possible that Groveland residents may have left the town, developed cancer and were thus considered a resident of the town to which they moved. It is also possible, however, that people who were not long-term residents and therefore not at risk of TCE exposure may have moved into Groveland and were subsequently diagnosed with cancer. It is assumed that these two migration patterns offset each other. The MDPH will continue to monitor cancer rates in West Newbury and Groveland to determine whether the cancer incidence rates change over time.
7. Hauling of sand and gravel from mining operations on the site may have resulted in the release of site-related contaminants to areas away from the site. Will the MDPH conduct monitoring to assure that this did not happen?
Since neither the MDPH nor ATSDR are regulatory agencies they do not conduct environmental monitoring. As part of the findings of a public health assessment, it can be determined that the monitoring of environmental media was not adequate for public health assessment purposes. In these cases, the Public Health Assessment may recommend that the particular insufficiency be remedied. In this particular instance, however, it is unlikely that contamination associated with the Groveland wells site could be dispersed via the transport of gravel and soil from the mining operations east of the Valley plant. Ground water monitoring wells were drilled in the mining pit and in 1984 no TCE was detected in waters drawn from this well. This compound and other small chlorinated hydrocarbons are relatively water soluble and would either wash from soil via precipitation or would volatilize into ambient air. Since there was no TCE contamination detected in ground water near the gravel mines and TCE would more likely to be found in ground water than in soil or gravel, dispersion of TCE from mining operations would, in all likelihood, not pose a health concern.
On October 26, 1993, this Public Health Assessment was released for public review and commentary. No comments were received by MDPH during the comment period ending on November 25, 1993.