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EPA Facility ID: NYD980753420
September 29, 2004

Pathway Analysis

This section of the PHA identifies potential and completed exposure pathways associated with past, present, and future uses of the site. An exposure pathway is the process by which an individual may be exposed to contaminants originating from a site. An exposure pathway has five elements: (1) a contaminant source, (2) environmental media and transport mechanisms, (3) a point of exposure, (4) a route of exposure, and (5) a receptor population.
The contaminant source is the origin of contaminant release to the environment (any waste disposal area or point of discharge). If the original source is unknown, the contaminant source is considered to be the environmental media (soil, air, biota, water) that are contaminated at the point of exposure. Environmental media and transport mechanisms carry contaminants from the source to points where people may be exposed. The point of exposure is a location where actual or potential human contact with a contaminated medium may occur. The route of exposure is the manner in which a contaminant actually enters or contacts the body (i.e., eating, drinking, breathing, touching). The receptor population includes people who are exposed or may be exposed to contaminants at a point of exposure.
Two types of exposure pathways are evaluated in a PHA. A completed exposure pathway exists when the criteria for all five elements of an exposure pathway are documented. A potential exposure pathway exists when any one of the five elements comprising an exposure pathway is not met or not known to have been met. An exposure pathway is considered to be eliminated, and therefore not evaluated, when any one of the five elements comprising an exposure pathway has not existed in the past, does not exist in the present, and will never exist in the future.
The main contaminants of concern associated with the MCW site are TCP and PCE. However, fluorenone, DNF, and TNF are potential contaminants of concern. They were detected in localized source areas at elevated concentrations and could act as a continuing source of contamination to groundwater and soil vapor. Known contaminant sources include subsurface drainage structures and associated soil contamination, soil contamination (primarily subsurface) that is likely associated with historic leaks and spills, and groundwater contamination from these structures and discharges. The locations of the two historic "surface" soil samples are now covered and inaccessible for direct human exposure. More recent shallow soil samples did not show evidence of contamination from MCW. The environmental media/mechanisms of contaminant transport are subsurface groundwater and soil vapor.
Completed Exposure Pathways
No completed exposure pathways have been documented for the MCW site. Past exposures to contaminated surface soil and chemical residues in and around buildings on the property may have occurred. Contamination was present. While at the site, individuals may have had contact with contaminants. The extent of past exposures, if any, are unknown and therefore cannot be evaluated. Areas of known surface contamination are now covered by C&D and soil piles. Other areas of the site appear to have disturbed through heavy equipment operations during the past 10 years and appear to have at least a slight covering of C&D/soil-gravel material. The two buildings at the site most likely to have residual contamination (the laboratory and the production buildings) are very decrepit, structurally unsound, and seldom used.
Potential Exposure Pathways
We identified a number of potential exposure pathways at the site. These pathways, which are discussed below, will be addressed by the remedy that the EPA selected for the site in its 2003 Record of Decision.
Pathways Related to Contaminated Leach Pits, Lagoons, and Subsurface Structures
Workers and others who service or clean drainage structures, or who otherwise dig into contaminated sediments, source area soils, or structures, could be exposed to contaminants at the MCW site. All of these areas are covered, no longer used, and generally inaccessible. There are no known plans for construction activities on the property. Future construction activities would not likely occur until the site is remediated and a question of site ownership is resolved.
Pathways Related to Contaminated Soil
Surface Soil
Individuals who work at or visit the site could be exposed to contaminated surface soil that may be present at the site; however, no such soil is known to be exposed at the present time. An area of known contaminated surface soil (two historic sample locations) is currently covered with piles of C&D debris and soil and rock. Other areas of the site appear to have been graded and covered with varying amounts of soil and gravel since MCW ended operations at the site. If existing cover material is removed or contaminated soil otherwise becomes exposed at the surface, exposure could occur. Exposure routes potentially include ingestion of, inhalation of, or direct contact with contaminated soil particles. If gardening were to occur at the site under a future change-of-use scenario, exposure could theoretically occur through plant uptake of near-surface contaminants and subsequent consumption of contaminated fruit or vegetables.
Subsurface Soil
Exposure pathways potentially associated with contaminated subsurface soil-primarily through construction or excavation-are the same as those for contaminated leach pits, lagoons, and subsurface structures. If construction activities occur at the site before site remediation, subsurface contaminants could be brought to the surface, thereby increasing the potential for exposure.
Pathways Related to Contaminated Groundwater
Private Wells
Persons who use contaminated well water could be exposed to site-related VOCs by ingestion (drinking), by contact (bathing), or by inhalation of volatilized contaminants (cooking or showering). The two private wells known to be in use near the MCW contaminant plume have been tested on a number of occasions. No VOCs were detected in these wells at concentrations above drinking water standards. These wells could, however, become contaminated in the future.
Public Water Supply Well
Groundwater contamination in Long Island is a particular concern because groundwater is the sole source of public water there. If SCWA's Carleton Avenue well field is ever affected by site-related contaminants in off-site groundwater, anyone served by that public water supply well could be exposed in the same manner as those using contaminated private wells. Monitoring data from the supply well for the previous 20 years have not shown any detectable levels of VOCs.
Pathways Related to Contaminated Soil Vapor
Significantly elevated concentrations of VOCs are present in soil vapor beneath the MCW site. Individuals who spend time in the on-site buildings could be exposed to VOCs through inhalation of indoor air contaminated by subsurface vapors. Whether such vapors have seeped into the buildings in the past or at present is unknown. People reportedly spend minimal amounts of time in the potentially affected on-site structures. Exposures could occur if new structures are built at the site without proper site remediation or engineering controls.
Elevated concentrations of VOCs are present in soil vapor immediately south of the MCW site near three homes. The levels detected, although low, suggest that indoor air quality would be measurably affected if vapor intrudes into the homes. Soil vapor concentrations can fluctuate over time, potentially resulting in some health effects. The extent of the subsurface VOC vapor plume in the direction of the house immediately east of the site is not known. The remedy selected in the EPA's March 2003 Record of Decision includes additional off-site soil vapor monitoring, as necessary.
Pathways Related to Contaminated Structures and Sewer Catch Basin
People who spent time in the on-site buildings in the past may have been exposed to residual contaminants, if present, in dust and on building surfaces. The two buildings with the greatest likelihood of contamination are the former laboratory and former production buildings. Both are in danger of collapse and are seldom entered, making current exposures unlikely. Exposure routes could include ingestion of, inhalation of, and direct contact with contaminated materials.
People who enter the sewer catch basin at the entrance to the site-mainly for maintenance or cleaning activities-could be exposed to sediments containing elevated levels of arsenic.

Public Health Implications

Evaluation for Adult and Children's Health Issues
Sampling to date shows the levels of contaminants in on-site surface soil do not exceed public health assessment comparison values for exposure by incidental ingestion of soil. The area of known surface soil contamination is currently covered by C&D debris and piles of dirt. Therefore, exposure to these levels in soil is unlikely unless site conditions change. We do not know the extent and nature of exposures that may have occurred in the past. There are no known exposures to contaminants detected in groundwater or soil vapor.
Elevated levels of several contaminants were detected in the subsurface soil. Some of these contaminant levels exceed public health assessment comparison values for exposure by incidental ingestion of soil. Other contaminants in subsurface soil exceed levels we would typically expect to find in the environment, but we currently have no comparison values or toxicity information for these chemicals. Exposure to the contaminants in subsurface soil under current site conditions is unlikely. If, however, these materials were dug up and became available for human contact, exposure to the contaminants could increase. The Recommendations and Public Health Action Plan sections of this document suggest measures that can reduce the potential for exposure to the contaminants in the subsurface soil.
Health Outcome Data Evaluation
NYSDOH has not evaluated health outcome data specifically for the MCW site. No completed exposure pathways have been identified for this site. On-site workers and trespassers may have been exposed to contaminants in surface soil, but is information is inadequate concerning levels of exposure and the number and identity of workers and trespassers. NYSDOH maintains several health outcome databases, which could be used to generate health outcome data for a specific area, if appropriate. These databases include the Cancer Registry, the Congenital Malformations Registry, vital records (birth and death certificates), and hospital discharge information.
Community Health Concerns Evaluation
Community members from neighborhoods near the MCW site attended a public meeting held by NYSDEC and NYSDOH in May 1999 and some contacted NYSDOH by phone. Concerns raised by these members of the public are summarized below. The public was invited to review the draft of this public health assessment during the public comment period, which ran from April 12, 2004 through May 28, 2004. We received no comments from the public during that period.
Concern that health effects from exposures to VOCs at MCW be monitored
As previously noted, there have been no documented exposures to site-related contaminants. The previous section, Health Outcome Data Evaluation, discusses information about disease incidence near chemical plants in general and in the general vicinity of the site. That section also notes some ongoing disease incidence investigation activities by NYSDOH.
Concern that schools above contaminated groundwater may be affected
TCP concentrations are the highest among contaminants of concern related to the MCW site in off-site groundwater. Although TCP and other VOCs volatilize from contaminated soil and sediment, TCP does not readily volatilize from groundwater. This is supported by the soil vapor results from NYSDEC's 2000 remedial investigation report. TCP was detected in soil vapor samples collected from beneath the site near contaminated subsurface structures and soil. However, no TCP was detected in off-site soil vapor samples. The off-site soil vapor samples were collected from an area above the more highly-contaminated groundwater, suggesting that TCP off-gassing from shallow groundwater near the site was not a concern. This would be even less of a concern with distance from the site as the groundwater contamination concentrations tend to decrease and the contamination migrates deeper into the subsurface groundwater.
Concern that on-site buildings will collapse
Residents have noted that on-site buildings are in an advanced state of decay and in danger of collapse. Individuals in or near the buildings at the time of collapse could be injured. The site occupant stated that individuals seldom enter the two buildings that appear to be most in danger of collapse. Trespassing at the site appears to be minimal. The buildings should be evaluated and condemned, razed, or stabilized, as appropriate. One of the buildings (the former laboratory) will be demolished and removed from the site as part of the EPA's selected remedy.
Concern that water in a nearby recharge basin is contaminated
Chemicals and wastewater were historically discharged into subsurface drainage structures at the site. Surface spills and discharges at the site would likely have either evaporated or, given the permeable nature of soil at the site, migrated downward into the ground. Consequently, subsurface soil and groundwater are contaminated beneath the site. However, some surface contamination may have entered storm drains near the site and moved to a receiving basin or stream. The recharge basin in question (about 18 blocks south on Beech Street), is unlikely to have received runoff from the site.


Subsurface drainage structures, soil, groundwater, soil vapor, and possibly buildings at the MCW site are contaminated with VOCs (primarily PCE and TCP) and several fluorenones at levels potentially of health concern. While individuals working at the site or trespassing at the site in the past may have been exposed to these contaminants, no exposures have been documented. Because data on possible historic exposures are not available, past exposures, if any, cannot be evaluated. Current occupants at the site are not known to be exposed, and significant exposures do not appear likely, judging from current site activities and because the two locations of known surface contamination are covered with soil and gravel. Additional data are needed to better determine the potential for exposure under future scenarios involving changes in site use and/or conditions. Future construction activities, particularly those involving excavation, could increase the potential for exposure to subsurface contaminants.
Groundwater contamination, consisting primarily of TCP, is migrating from the site. Private water supply wells and a public water supply well near the site have not been adversely affected by site-related contaminants. These wells could, however, become contaminated in the future.
Contaminated soil vapor beneath the MCW site is primarily limited to on-site areas. VOCs in soil vapor do not currently appear to be a significant threat to indoor air in homes adjacent to the site; however, additional testing is needed.
At least two on-site buildings appear to be in danger of collapse. These buildings may be contaminated from former MCW activities but are seldom entered. Demolition of one building-the former laboratory-began in August 2004. The other building will be structurally evaluated. Two radioactive metals, thorium and uranium, were listed as chemicals used in the laboratory. These materials were confined to the laboratory and if they were used, it was at low levels that did not require a license. A perimeter radioactive survey was performed at the lab building in 2003 with negative results. Another survey is planned by EPA after demolition.
On the basis of ATSDR's current guidance for assigning a health hazard category to a site (Appendix C), the MCW site poses no public health hazard at the present because there are no known exposures to site-related contaminants. Significant contamination is present beneath and near the site, however, and future exposure is possible if contaminated groundwater or soil vapor migrate into supply wells or basements. Additionally, changes in site use and/or construction activities at the site could result in exposure to subsurface contaminants. Consequently, the site poses an indeterminate public health hazard for the potential future exposures. Individuals working or trespassing at the site in the past may have been exposed to contaminants; however, because data on historic exposures are not available, past exposures, if any, cannot be evaluated.
The public was invited to review the draft of this public health assessment during the public comment period, which ran from April 12, 2004 through May 28, 2004. We received no comments from the public during that period.


  1. Source areas and subsurface drainage structures at the site should be remediated. This will substantially diminish the potential for future construction-related exposures and also eliminate the ongoing source of VOC contaminants to soil vapor and groundwater.

  2. Until the site is remediated, exposures to subsurface contamination should be minimized by proper engineering controls and monitoring during excavation and by proper handling of all contaminated subsurface materials. Although contamination in an adjacent sewer basin may not be site related, the appropriate municipal agency(ies) should be notified about the need for proper precautions during maintenance activities.

  3. All soil and sediment analysis for the MCW site should include fluorenones, TCP, DNF, and TNF. Consideration should also be given to testing groundwater and soil vapor for fluorenone, DNF, TCP and TNF, if appropriate based on chemical properties.

  4. A private well survey of the nearby homes should be done to determine the actual number of private wells in use. Owners of homes with wells should be encouraged to connect to public water, if available, to reduce the use of wells that are vulnerable to site and non-site related contaminants.

  5. Routine monitoring of public water supply wells, as required by NYSDOH's Part 5 public water supply regulations, should continue.

  6. Highly-contaminated groundwater should be treated to remove the ongoing contaminant source to Long Island's sole source aquifer and the continuing threat to private and public water supply wells.

  7. Soil vapor should be retested to evaluate current conditions beneath the site. This should include evaluating vapors near homes to the south and east of the site. If warranted based on the results from soil vapor, indoor air should also be tested for the presence of site-related contaminants.

  8. Buildings at the site could present a physical hazard should they be used in the future. All on-site buildings should be inspected for structural integrity and razed or stabilized, as appropriate.

Public Health Action Plan

The Public Health Action Plan (PHAP) for the MCW site contains a description of actions to be taken by ATSDR and/or NYSDOH following completion of this PHA. The purpose of the PHAP is to ensure that this PHA identifies public health hazards and provides a plan of action designed to mitigate and prevent adverse human health effects resulting from potential exposures to hazardous substances at or near the site. Included is a commitment on the part of ATSDR and/or NYSDOH to follow up on this plan to ensure that it is implemented. The public health actions taken and planned by ATSDR and/or NYSDOH are as follows:

Public Health Actions Taken
  1. Potentially affected private water supply wells have been tested on several occasions by SCDHS for site related contaminants.

  2. Potentially affected public water supply wells have been routinely monitored by the SCWA pursuant to NYSDOH and SCDHS requirements.

  3. NYSDOH has worked with NYSDEC during the site investigations to ensure that potential exposure pathways are addressed.

  4. NYSDOH has worked with EPA during the development of remedial measures to ensure that current and potential exposure pathways will be minimized, eliminated, or otherwise effectively addressed.
Public Health Actions Proposed
  1. NYSDOH will work with SCDHS to ensure that potentially affected water supply wells continue to be tested for site-related contaminants.

  2. NYSDOH will work with EPA, NYSDEC, and SCDHS to ensure that appropriate notifications are made about the need for proper controls during maintenance and excavation activities at and near the MCW site.

  3. NYSDOH will work with EPA during the implementation of remedial measures to ensure that community members are not exposed to contaminants during clean-up activities.

  4. ATSDR and NYSDOH will coordinate with the appropriate agencies regarding actions to be taken in response to those recommendations provided in this PHA for which no plan of action has yet been developed.

  5. ATSDR and NYSDOH will provide follow-up to the PHAP as needed, outlining the actions completed and those in progress. Follow-up reports will be placed in repositories that contain copies of this health assessment, and will be provided to persons who request it.


[EPA] US Environmental Protection Agency (Region 2). 2003. Record of Decision, MacKenzie Chemical Works Superfund Site, Central Islip, Suffolk County, New York. New York, New York.
NUS Environmental Corporation. 1983. Potential hazardous waste site: executive summary and preliminary assessment. Pittsburgh, Pennsylvania
[NYSDEC] New York State Department of Environmental Conservation. 1992. Phase II investigation, MacKenzie Chemical site. Albany, New York.
[NYSDEC] New York State Department of Environmental Conservation. 2000. Remedial investigation/feasibility study, MacKenzie Chemical site. Albany, New York.
[NYSDOH] New York State Department of Health. 1993. Sanitary Code, Title 10, Part 5, NYCRR Drinking Water Supplies. Albany, New York.
[NYSDOH] New York State Department of Health. 2003. Tetrachloroethene (perc) in indoor and outdoor air (fact sheet). Albany, New York. Available at URL:
[SCDHS] Suffolk County Department of Health Services. 1993. Results of profile drilling downgradient of MacKenzie Chemical, internal memorandum. Hauppauge, New York.
US Bureau of the Census. 2001. 2000 Census of population and housing summary file 1(SF1). US Department of Commerce. Washington, DC.
US Bureau of the Census 2002. 2000 Census of population and housing summary file 3 (SF3). US Department of Commerce. Washington, DC.
Windholz M, Budavari S, Stroumtsos LY, Fertig MN, editors. 1976. The Merck Index: an encyclopedia of chemicals and drugs, 9th ed. Rahway, New Jersey: Merck and Co., Inc.

Preparers of Report

New York State Department of Health Authors
Zwelonke Ian Ushe
Assistant Sanitary Engineer
Bureau of Environmental Exposure Investigation
Thomas Johnson, Ph.D.
Research Scientist
Bureau of Toxic Substance Assessment
Steven P. Forand
Research Scientist
Bureau of Environmental and Occupational Epidemiology
Rebecca G. Mitchell
Assistant Sanitary Engineer
Bureau of Environmental Exposure Investigation
William Gilday, P.E.
Assistant Sanitary Engineer
Bureau of Environmental Exposure Investigation
Agency for Toxic Substances and Disease Registry
Regional Representative
Arthur Block
Regional Operations
Office of the Assistant Administrator
Technical Project Officer
Greg Ulirsch
Technical Project Officer
Division of Health Assessment and Consultation
Superfund Site Assessment Branch


This Public Health Assessment was prepared by the New York State Department of Health under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health assessment was initiated.

Technical Project Officer, SSAB, DHAC
The Division of Health Assessment and Consultation (DHAC), ATSDR, has reviewed this public health assessment, and concurs with its findings.


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