PUBLIC HEALTH ASSESSMENT
LEHIGH VALLEY RAILROAD DERAILMENT SITE
(a/k/a LEHIGH VALLEY RAILROAD
TOWN OF LEROY, GENESEE COUNTY, NEW YORK
A December 1970 railroad derailment in the Town of LeRoy, Genesee County, spilled 30,000 gallons of trichloroethene and caused extensive groundwater contamination. Little remediation was conducted at the time of the spill and there was no follow-up regarding the spill until January 1991. An investigation conducted in 1991 found that the trichloroethene had migrated at least 3.5 miles from the spill site and contaminated over 35 private water supply wells. Bottled water was immediately provided to users with trichloroethene levels above the New York State Department of Health drinking water standard, and individual wholehouse treatment systems were subsequently installed.
The Lehigh Valley Railroad Derailment site was a public health hazard in the past because of exposures to trichloroethene in some private drinking water supply wells at levels that could pose an increased risk of cancer and noncancer effects. Also, studies suggest, but cannot prove, that the developing fetus may have increased sensitivity to the effects of trichloroethene. The site currently presents no apparent public health hazard because treatment systems were installed to reduce exposures. These actions will help to ensure that potential risks are minimized.
The New York State Department of Health (NYS DOH) and the Department of Environmental Conservation (NYS DEC) have met with the community several times to inform them of the contamination, to provide advice and to listen to their concerns. Residents continue to be concerned about past exposures in private drinking water wells and progress toward a long-term source of alternate drinking water.
In 1992, the NYS DOH released the results of a health and exposure survey of residents living near the site. The proportion of the exposed persons reporting symptoms was slightly higher than unexposed persons, but not statistically significantly higher. The site is being considered for inclusion in the NYS Volatile Organic Compounds (VOC) Registry. Also, the NYS DOH Cancer Surveillance Program is studying cancers in the area, comparing observed numbers of cases to expected numbers of cases for total cancers and specific types of cancers.
A March 1997 Record of Decision calls for the installation of a public water supply line to the affected area. The NYS DOH and the Agency for Toxic Substances and Disease Registry (ATSDR) will work with the US Environmental Protection Agency (US EPA) and NYS DEC to ensure that all private wells which are contaminated or considered to be at risk will be connected to the waterline. NYS DOH and the county health departments will continue monitoring affected wells until the waterline is extended. Also, selected private wells will be monitored to determine whether the plume migrates and contaminates additional wells.
The purpose of this public health assessment is to evaluate past and potential future exposures to site-related contaminants. It fulfills the congressional mandate for a public health assessment for each site, within one year of being proposed to the National Priorities List (NPL). For Lehigh Valley, the only completed exposure pathway is for ingestion of trichloroethene in drinking water from private drinking water wells. Water from these wells was contaminated for a period of up to about 20 years, until carbon filters were installed to remove contaminants. The primary health concerns are for past exposures to trichloroethene in private drinking water wells and the need for a long-term alternative to using contaminated groundwater as a source for drinking water.
The Lehigh Valley Railroad Derailment site is in a rural area in the Town of LeRoy, Genesee County, near the Livingston and Monroe County borders (Figure 1, Appendix A). Residences are situated throughout the area.
In December 1970, a train derailed at the intersection of the railroad and Gulf Road. Two 15,000 gallon tank cars containing trichloroethene ruptured and spilled their contents onto the ground in an area with private drinking water wells. In early 1971, residents adjacent to the spill site complained of solvent-like odors in their drinking water. Based on the odors and some limited sampling, the railroad company provided either a carbon filter or a cash settlement to those with affected water supplies. The only remediation by the railroad company at the spill site was to construct ditches and berms in the spill area, which were flooded with water in an attempt to flush the trichloroethene out of the ground. No further remediation occurred.
In 1989, the New York State Department of Health (NYS DOH) sampled a private water supply as part of an investigation for another nearby site. The sample contained trichloroethene. Based on reports of trichloroethene being spilled at the 1970 Lehigh Valley Railroad Derailment, a private well sampling program was initiated to determine if this was the source of the contamination. In 1991, the NYS DOH, in cooperation with the Genesee, Livingston and Monroe County Health Departments, sampled private water supplies to the east of the spill site. These sample results showed that the trichloroethene plume had migrated from the Lehigh Valley Railroad Derailment site and that several wells were contaminated with trichloroethene above the NYS DOH and United States Environmental Protection Agency (US EPA) drinking water standard of 5 micrograms per liter (mcg/L) for public water supplies. The NYS DOH and the New York State Department of Environmental Conservation (NYS DEC) requested assistance from the US EPA, which subsequently installed granular activated carbon (GAC) treatment systems on 35 private water supplies. The NYS DEC installed GAC treatment systems on 3 additional private water supply wells.
Groundwater is the sole source for drinking water in this rural area. Due to the shallow overburden and highly fractured bedrock, contaminants from the site have migrated about 3.5 miles to the east and discharge via springs into the trout stream, Spring Creek. Since January 1991, over 120 private residential and commercial drinking water supply wells in the area have been tested. Thirty-eight of these water supplies contained trichloroethene above the NYS DOH drinking water standard (Figure 1, Appendix A). GAC treatment systems were installed on all 38 water supply wells. The NYS DEC is currently responsible for the operation and maintenance of the treatment systems.
In November 1991, the site was added to the NYS Registry of Inactive Hazardous Waste Disposal Sites. On March 28, 1997, the NYS DEC signed a Record of Decision (ROD) (NYS DEC 1997) for the Lehigh Valley Railroad Derailment site. The remedial action plan for the site includes:
- Design and construction of a waterline extension which will connect all affected and threatened residences to a public water supply. The waterline extension for this site will extend from a new waterline to be built from the Monroe County Water Authority water main in Bergen down Route 19 to the Village of LeRoy. Water supply may be temporarily supplied by the Village of LeRoy until the water main is installed down Route 19. The waterline extension will be designed to provide fire flow for the current demand.
- Tentative expansion of the waterline extension component of the remedy will include the section from Spring Street, west along George Street/Flint Hill Road to Lime Rock Road. A final determination of the route will be made based upon additional engineering and hydrogeologic analyses to be conducted during the design phase of the waterline extension.
- Design of source control measures which will include a detailed pilot study.
- Excavation and treatment (vapor extraction) of about 10,000 cubic yards of trichloroethene-contaminated soil at the former spill site. This will include removal and replacement of a portion of Gulf Road. Treated soil will be placed back on site.
- Installation of a bedrock vapor extraction system within the approximately 10 acre non-aqueous phase liquid (NAPL) zone.
- Initiation of a long term monitoring program designed to protect human health and the environment during and after construction of the above remedial plan.
Due to the scope of the contamination problems noted at the site, the NYS DEC also nominated the site for the NPL, better known as the Federal Superfund List. US EPA proposed the site to the NPL in July 1998; the site was added to the NPL in January 1999.
In January 1991, the NYS DOH, with representatives from the Genesee, Monroe and Livingston County Health Departments and NYS DEC, visited the site to familiarize themselves with the area of the spill and locations of private drinking water wells in the area. There were no obvious physical hazards associated with the site. There was evidence that the railroad track bed was being used by all-terrain vehicle operators for recreation. In June 1991, NYS DOH again visited the site with representatives of the US EPA to familiarize them with the site and the locations of private wells in the area.
A site visit was made by Mr. David Napier of the NYS DOH during October 1996. Conditions had not changed since previous site visits. The site is accessible, but there is no evidence of trespass and no obvious physical hazards associated with the site. Representatives from NYS DOH and county health departments collected water samples from private wells in the area on a quarterly basis from October 1991 through 1994. Since 1994, sampling has been conducted on a semi-annual basis. The sampling is to monitor the status of the contaminant plume, to evaluate potential exposures, and if necessary, request the installation of additional treatment systems. In March 1999, NYS DOH collected 32 water samples from private wells around the periphery of the site. These data were used to determine if any additional wells were contaminated that would need to be connected to the public waterline extension.
The NYS DOH estimated, from the 1990 Census (US Bureau of the Census 1991), that 3,807 people live within one mile of the wells which have detectable levels of trichloroethene contamination. Of this population, 96.3 percent is of the white race, 2.8 percent of the black race and 0.9 percent of other races. Within this area, 9.1 percent of the population is under 6 years of age, 18.9 percent is 6 to 10 years of age, 60.4 percent is 20 to 64 years of age and 11.6 percent is 65 years of age or older. In 1990, there were 856 females of reproductive age (ages 15-44) within one mile of the contaminated wells. The median household income in LeRoy (US Bureau of the Census 1992), where the derailment occurred, was $31,603 in 1989, with 6.5 percent of the population living below the poverty level.
As part of a 1993 Remedial Investigation, NYS DEC's consultant (Rust Environment and Infrastructure of New York (1996)) installed 55 monitoring wells at 17 locations. Up to four wells were installed at each location to monitor groundwater at different depths. In the area adjacent to the spill site, trichloroethene was detected at a maximum concentration of 58,000 mcg/L. The average level of trichloroethene in the spill area ranged from 1,000 to 10,000 mcg/L depending on the depth of the well. Due to the high levels of trichloroethene, these samples had to be diluted for analysis. A breakdown product of trichloroethene, cis-1,2-dichloroethene, was not detected in most samples, possibly due to the dilution. Outside of the spill area, the maximum level of trichloroethene detected was 2,100 mcg/L; most samples contained trichloroethene below 100 mcg/L.
The NYS DOH has collected water samples at 140 private wells in the area. Trichloroethene was detected in 49 private wells at concentrations from 0.5 to 7,200 mcg/L. Although a couple of samples had high levels, most of the contaminated wells contain trichloroethene at levels between 5 and 100 mcg/L. Concentrations from 0.5 to 38 mcg/L of cis-1,2-dichloroethene were detected in a few private wells adjacent to the site. Although carbon treatment systems were provided to some of the residents with contaminated wells by the railroad company immediately after the spill, there was no follow-up testing and maintenance of the systems. Residents with contaminated water supplies may have been exposed to site-related contaminants via ingestion, inhalation, and dermal contact for up to about 20 years.
Subsurface soils (1-6 feet below ground surface) at the spill site are contaminated with trichloroethene at levels up to 550 milligrams per kilogram (mg/kg) (Dunn Geoscience and Engineering 1993b). The soil contaminated area encompasses an irregularly-shaped source area of about 1.5 acres, with an average concentration of 100 mg/kg of trichloroethene. The maximum concentration of 550 mg/kg was detected in soil in a bedrock fracture. The potential for exposure to these levels of trichloroethene is unlikely because the contaminant was only detected in on-site subsurface soil, not in surface soil. However, since the site has not been remediated, the contaminated subsurface soil, along with pure product within the bedrock, continues to act as a source of contamination to the groundwater. Contamination measured to date in Spring Creek has been less than 3.0 mcg/L which is below levels of health concern (Dunn Geoscience and Engineering 1993a).
In 1991, the NYS DOH held three public informational meetings and distributed fact sheets to community members and interested parties. The purpose of the meetings was to inform them of the contamination, to provide advice and to listen to their concerns. Affected residents were advised not to drink the water and on how to take additional precautions to reduce potential exposure from cooking and bathing. Bottled water was provided to people whose wells contained trichloroethene above the NYS DOH drinking water standard until treatment systems were installed. The NYS DEC has assumed responsibility for sampling these water supplies and operation and maintenance of the treatment systems. The NYS DOH and the Genesee, Livingston and Monroe County Health Departments sample additional private wells in the area to monitor the contaminant plume and determine if additional wells are contaminated.
On March 4, 1997, the NYS DEC and NYS DOH held a public meeting to discuss a proposed remedial action plan for the site. The components of the proposal are: 1) extension of public water supply lines to the affected area, 2) excavation and on-site treatment of contaminated soils at the spill site, and 3) installation of bedrock vapor extraction wells to remove trichloroethene from the bedrock. On January 27, 1999 NYS DEC held a public meeting with residents to discuss the design of the waterline extension. Residents continue to be concerned about past exposures to trichloroethene in private drinking water and progress toward a long-term source of alternate drinking water.
The public was invited to review a draft of this public health assessment during the public comment period, which ran from July 14 to August 15, 2000. We received no comments from residents or organizations.
To evaluate the potential health risks from contaminants of concern associated with the Lehigh Valley Railroad Derailment site, the NYS DOH assessed the risks for cancer and noncancer health effects. The risks of health effects depend on contaminant concentration, exposure route, exposure frequency and duration. Additional information on the NYS DOH assessment for this site is in Appendix B.
Prior to 1991, we do not know for how long or at what concentrations people were exposed to trichloroethene in their private water supply wells. However, exposure to trichloroethene may have occurred for a period of about 20 years, from 1971 when solvent-like odors were detected in some residents' drinking water to 1991 when trichloroethene was detected in about 35 wells.
Trichloroethene was detected in the private wells at concentrations from 0.5 to 7,200 mcg/L. Although a couple of samples had high levels, most of the contaminated wells contain this contaminant at levels between 5 and 100 mcg/L. A break-down product of trichloroethene, cis-1,2-dichloroethene, was also detected in a few wells adjacent to the site at concentrations from 0.5 to 38 mcg/L. Levels above 5 mcg/L exceed NYS DOH public drinking water supply standards for each of these chemicals.
Past, current and potential future exposures to contaminants in drinking water supplies has/can occur via ingestion, dermal contact and inhalation from uses such as drinking, cooking, showering, bathing or other household uses. Although exposure varies depending on an individual's lifestyle, each of these exposure routes contributes to the overall daily intake of contaminants and, thus, increases the potential for chronic health effects.
Trichloroethene causes cancer in laboratory animals exposed to high levels over their lifetimes. Chemicals that cause cancer in laboratory animals may also increase the risk of cancer in humans who are exposed to lower levels over long periods of time. Some limited data from studies of people who ingested this and other chemicals in drinking water are suggestive, although inconclusive, that exposure to trichloroethene in drinking water may increase the risk of cancer in humans. Based on the human and animals studies and limited sampling of private wells, people drinking water over a period of 20 years containing trichloroethene at levels ranging from about 5 mcg/L to 100 mcg/L (the range of water concentrations most representative of people's potential exposure) may have a low increased risk of developing cancer. Toxicological data are inadequate to assess the carcinogenic potential of cis-1,2-dichloroethene (ATSDR, 1996).
Trichloroethene and cis-1,2-dichloroethene also can produce a variety of non-carcinogenic effects, primarily to the liver, kidneys and nervous system. Chemicals that cause health effects in humans and/or animals after high levels of exposure may also pose a risk to humans who are exposed to lower levels over long periods of time. Although the risks of non-carcinogenic effects from past exposures to trichloroethene in private drinking water supply wells are not completely understood, the existing data suggest that risks would be minimal for persons exposed to trichloroethene in drinking water at levels ranging from about 5 mcg/L to 100 mcg/L. The risks of noncarcinogenic effects to persons exposed to cis-1,2-dichloroethene at levels up to 38 mcg/L would be minimal.
The NYS DOH maintains several health outcome data bases which could be used to generate site-specific data, if warranted. These data bases include the cancer registry, the congenital malformations registry, the heavy metals registry, the occupational lung disease registry, vital records (birth and death certificates) and hospital discharge information.
In May 1991, the NYS DOH initiated a health and exposure survey for residents living near the site. Questionnaires were distributed to 89 households from which water samples were collected as part of the investigation of the site. Of these, 74 households participated in the survey for an overall response rate of 83.1 percent. Questionnaires were completed by 226 individuals in these households. The questionnaire asked for information about water usage, historical water problems and individual health information. The survey data were separated into groups according to exposure status. The unexposed group included 151 individuals in households with no detectable level of contamination in the water. The exposed group included 75 individuals in households with a detectable level of contamination in the water. A summary of the results of the survey was released in November 1992 (NYS DOH 1992). The proportion of the exposed persons reporting symptoms was slightly higher than the proportion of unexposed persons reporting symptoms, but the difference was small. The difference was not statistically significant, but the power of the statistical test was low due to the small number of people in the investigation.
This site is being considered for inclusion in the NYS VOC Exposure Registry. The registry is currently being piloted on selected sites before additional sites are included. If this site is selected in the future, residents of households who were exposed in the past to VOCs from private well drinking water supplies will be asked by the NYS DOH to participate.
The exposure registry allows long-term follow-up on the health status of persons with documented exposures to VOCs from this site as well as persons exposed to VOCs at other selected sites in New York State. An exposure registry such as this one is a resource for research that may help us learn whether exposures to VOCs are related to health effects. People who are enrolled in the Registry will be kept informed of any research results that come from the Registry data.
Also, in 1995, in response to citizen concerns about the number of cancer cases in their community, the Genesee County Public Health Director asked the NYS DOH Cancer Surveillance Program for an investigation of cancer in the Hamlet of Limerock, Town of LeRoy. A study of cancers diagnosed from 1993 to 1997 among residents of ZIP code 14482, comparing observed numbers of cases to expected numbers of cases for total cancers and specific types of cancer, is expected to be completed in 2001.
The ATSDR Child Health Initiative emphasizes examining child health issues in all of the agency activities, including evaluating child-focused concerns through its mandated public health assessment activities. The ATSDR and the NYS DOH consider children when evaluating exposure pathways and potential health effects from environmental contaminants. We recognize that children are of special concern because of their greater potential for exposure from play and other behavior patterns. Children sometimes differ from adults in their susceptibility to the effects of hazardous chemicals, but whether there is a difference depends on the chemical. Children may be more or less susceptible than adults to health effects from a chemical and the relationship may change with developmental age.
The possibility that children or the developing fetus may have increased sensitivity to trichloroethene (the primary contaminant associated with the Lehigh Valley Railroad Derailment site) was taken into account when evaluating the potential health risks associated with the site. The potential for trichloroethene to cause adverse effects in children and/or the offspring of laboratory animals has been assessed in several studies.
For laboratory animals, when pregnant animals are exposed by ingestion and/or inhalation to large amounts of trichloroethene, adverse effects on the normal development of the offspring are observed (ATSDR, 1997). In most, but not all of these studies, the high amounts of trichloroethene also caused adverse health effects on the parent animal. The estimated levels of exposure to trichloroethene at concentrations of 5 mcg/L up to 100 mcg/L in private water supply wells near the Lehigh Valley Railroad Derailment site were compared to the exposure levels in the animal studies in which adverse health effects were observed, and were lower.
Human studies on exposure to trichloroethene in drinking water during pregnancy suggest that there may be an association between oral trichloroethene exposure and childhood leukemia and birth defects (e.g., neural tube defects, oral cleft defects and congenital heart defects) (ATSDR, 1997). In each of these studies, the mothers were exposed to chemicals other than trichloroethene; therefore, the observed effects on the developing fetus may have been from some factor other than trichloroethene. Thus, these studies suggest, but cannot prove, that the developing fetus may have increased sensitivity to the effects of trichloroethene. The actions taken to reduce exposure to trichloroethene in private wells will help ensure that the potential risks are minimized.
Based on the Agency for Toxic Substances and Disease Registry's public health hazard category classification (see Appendix C), the Lehigh Valley Railroad Derailment site was a public health hazard in the past because of exposures to trichloroethene in some private drinking water supply wells at levels that could pose an increased risk of cancer and noncancer effects. Studies suggest, but cannot prove, that the developing fetus may have increased sensitivity to the effects of trichloroethene. Exposure to trichloroethene has occurred via ingestion, inhalation and dermal contact for possibly as long as about 20 years. The actions taken to reduce exposure to trichloroethene in private wells will help ensure that the potential risks are minimized. The site currently presents no apparent public health hazard because treatment systems were installed to reduce exposures. Future exposure could occur if trichloroethene migrates into additional private water supply wells, if new wells are installed within the contaminant plume or if treatment systems are not maintained.
- The remedial action plan presented in the NYS DEC Record of Decision (ROD) should be carried out to provide an alternate water supply and permanently dissociate people from the contaminated water.
- The affected private drinking water supply wells and treatment systems should be tested periodically and maintained to ensure that a continuous supply of potable water is provided. The treatment systems should remain in use until the raw groundwater in the affected wells consistently meets NYS DOH drinking water standards, or until an acceptable permanent alternate drinking water supply is provided.
- Changes in groundwater flow or groundwater table level, due to man-made or natural activities (i.e., flood or drought), could cause the contaminant plume to migrate and affect additional wells. Therefore, other potentially contaminated water supplies should continue to be monitored.
- The NYS DEC should continue to monitor the nature and extent of the contamination, including the site's impact on nearby streams and creeks (i.e., Spring Creek).
- A formal mechanism should be developed to ensure that potential groundwater users are informed of the contaminated groundwater.
The Public Health Action Plan (PHAP) for the Lehigh Valley Railroad Derailment site describes the actions to be taken by ATSDR and/or the NYS DOH following completion of this public health assessment. The purpose of the PHAP is to ensure that this public health assessment not only identifies public health hazards, but provides a plan of action designed to mitigate and prevent adverse human health effects resulting from present and/or future exposures to hazardous substances at or near the site. ATSDR and/or the NYS DOH will ensure that this plan is implemented. The public health actions for the Lehigh Valley Railroad Derailment site are as follows:
- ATSDR and the NYS DOH will coordinate with the NYS DEC and US EPA to implement the recommendations in this public health assessment.
- ATSDR will provide follow-up to this PHAP as necessary, outlining the actions completed and those in progress. The follow-up report will be placed in repositories that contain copies of this public health assessment, and will be provided to persons who request it.
- NYS DOH staff have had many one-to-one discussions with residents via phone calls and during sampling visits to individual homes. NYS DOH staff have also discussed health effects and community health concerns at public meetings conducted for this site. The NYS DOH will continue to conduct these and other community health education as appropriate.
- The NYS DOH and County Health Departments will periodically test private water supply treatment systems to ensure that a continuous supply of uncontaminated water is available until a permanent drinking water supply is provided.
- The NYS DOH is developing a registry of persons exposed to volatile organic compounds (VOCs) in drinking water. People who were exposed to VOCs through ingestion of contaminated drinking water will be considered for inclusion in the registry.
ATSDR will reevaluate and expand the PHAP as needed. New environmental, toxicological, or health outcome data, or the results of implementing the above proposed actions may determine the need for additional actions at the site.
Agency for Toxic Substances and Disease Registry (ATSDR). 1997. Toxicological Profile for Trichloroethylene. U.S. Department of Health and Human Services. Atlanta, Georgia: U.S. Public Health Service.
Agency for Toxic Substances and Disease Registry (ATSDR). 1996. Toxicological Profile for 1,2-Dichloroethene. Update. U.S. Department of Health and Human Services, Atlanta, Georgia.
Agency for Toxic Substances and Disease Registry (ATSDR). 1995. Toxicological Profile for Trichloroethene. Update Draft. U.S. Department of Health and Human Services, Atlanta, Georgia.
Agency for Toxic Substances and Disease Registry (ATSDR). 1992. Public Health Assessment Guidance Manual. U.S. Department of Health and Human Services, Atlanta, Georgia.
Dunn Geoscience and Engineering Co., P.C. 1993a. Domestic Well and Initial Environmental Sampling Report, Lehigh Valley Railroad Derailment Site RI/FS.
Dunn Geoscience and Engineering Co., P.C. 1993b. Site Soil Investigation Report, Lehigh Valley Railroad Derailment Site RI/FS.
New York State Department of Health. 1992. Lehigh Valley Railroad Spill: Summary of the Health and Exposure Survey Report. November.
New York State Department of Environmental Conservation. 1997. Record of Decision, Lehigh Valley Railroad Derailment Site.
Rust Environment & Infrastructure of New York. 1996. Remedial Investigation Report, Lehigh Valley Railroad Derailment Site.
United States Bureau of the Census. 1991. 1990 Census of Population and Housing Summary Tape File 1B. United States Department of Commerce.
United States Bureau of the Census. 1992. 1990 Census of Population and Housing Summary Tape File 3A, CD-ROM. United States Department of Commerce.
New York State Department of Health
Public Health Specialist (Environment)
Bureau of Environmental Exposure Investigation
Donald W. R. Miles
ATSDR Grant Coordinator
Bureau of Environmental Exposure Investigation
Joel H. Kaplan
Bureau of Toxic Substance Assessment
Thomas B. Johnson, Ph.D.
Bureau of Toxic Substance Assessment
Agency for Toxic Substances and Disease Registry
Office of the Assistant Administrator
Technical Project Officer
Technical Project Officer
Division of Health Assessment and Consultation
Superfund Site Assessment Branch
The public health assessment for the Lehigh Valley Railroad Derailment site 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.
Greg V. Ulirsch
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation (DHAC), ATSDR, has reviewed this public health assessment and concurs with its findings.
Lisa C. Hayes
(for) Acting Chief, SSAB, DHAC, ATSDR
To evaluate the potential health risks from contaminants of concern associated with the Lehigh Valley Road Derailment site, the New York State Department of Health assessed the risks for cancer and noncancer health effects.
Increased cancer risks were estimated by using site-specific information on exposure levels for the contaminant of concern and interpreting them using cancer potency estimates derived for that contaminant by the US EPA or, in some cases, by the NYS DOH. The following qualitative ranking of cancer risk estimates, developed by the NYS DOH, was then used to rank the risk from very low to very high. For example, if the qualitative descriptor was "low", then the excess lifetime cancer risk from that exposure is in the range of greater than one per million to less than one per ten thousand. Other qualitative descriptors are listed below:
Excess Lifetime Cancer Risk
|equal to or less than one in a million||very low|
|greater than one in a million to less than one in ten thousand||low|
|one in ten thousand to less than one in a thousand||moderate|
|one in a thousand to less than one in ten||high|
|equal to or greater than one in ten||very high|
An estimated increased excess lifetime cancer risk is not a specific estimate of expected cancers. Rather, it is a plausible upper bound estimate of the probability that a person may develop cancer sometime in his or her lifetime following exposure to that contaminant.
There is insufficient knowledge of cancer mechanisms to decide if there exists a level of exposure to a cancer-causing agent below which there is no risk of getting cancer, namely, a threshold level. Therefore, every exposure, no matter how low, to a cancer-causing compound is assumed to be associated with some increased risk. As the dose of a carcinogen decreases, the chance of developing cancer decreases, but each exposure is accompanied by some increased risk.
There is general consensus among the scientific and regulatory communities on what level of estimated excess cancer risk is acceptable. An increased lifetime cancer risk of one in one million or less is generally considered an insignificant increase in cancer risk.
For noncarcinogenic health risks, the contaminant intake was estimated using exposure assumptions for the site conditions. This dose was then compared to a risk reference dose (estimated daily intake of a chemical that is likely to be without an appreciable risk of health effects) developed by the US EPA, ATSDR and/or NYS DOH. The resulting ratio was then compared to the following qualitative scale of health risk:
Qualitative Descriptions for
Noncarcinogenic Health Risks
Ratio of Estimated Contaminant
Intake to Risk Reference Dose
|equal to or less than the reference dose or minimal risk level||minimal|
greater than one to five times the reference dose or minimal risk level
|greater than five to ten times the reference dose or minimal risk level||moderate|
|greater than ten times the reference dose or minimal risk level||high|
Noncarcinogenic effects unlike carcinogenic effects are believed to have a threshold, that is, a dose below which adverse effects will not occur. As a result, the current practice is to identify, usually from animal toxicology experiments, a no-observed-effect-level (NOEL). This is the experimental exposure level in animals at which no adverse toxic effect is observed. The NOEL is then divided by an uncertainty factor to yield the risk reference dose. The uncertainty factor is a number which reflects the degree of uncertainty that exists when experimental animal data are extrapolated to the general human population. The magnitude of the uncertainty factor takes into consideration various factors such as sensitive subpopulations (for example, children or the elderly), extrapolation from animals to humans, and the incompleteness of available data. Thus, the risk reference dose is not expected to cause health effects because it is selected to be much lower than dosages that do not cause adverse health effects in laboratory animals.
The measure used to describe the potential for noncancer health effects to occur in an individual is expressed as a ratio of estimated contaminant intake to the risk reference dose. If exposure to the contaminant exceeds the risk reference dose, there may be concern for potential noncancer health effects because the margin of protection is less than that afforded by the reference dose. As a rule, the greater the ratio of the estimated contaminant intake to the risk reference dose, the greater the level of concern. A ratio equal to or less than one is generally considered an insignificant (minimal) increase in risk.
|CATEGORY / DEFINITION||DATA SUFFICIENCY||CRITERIA|
|A. Urgent Public Health Hazard
This category is used for sites where short-term exposures (< 1 yr) to hazardous substances or conditions could result in adverse health effects that require rapid intervention.
|This determination represents a professional judgement based on critical data which ATSDR has judged sufficient to support a decision. This does not necessarily imply that the available data are complete; in some cases additional data may be required to confirm or further support the decision made.||Evaluation of available relevant information* indicates that site-specific conditions or likely exposures have had, are having, or are likely to have in the future, an adverse impact on human health that requires immediate action or intervention. Such site-specific conditions or exposures may include the presence of serious physical or safety hazards.|
|B. Public Health Hazard
This category is used for sites that pose a public health hazard due to the existence of long-term exposures (> 1 yr) to hazardous substance or conditions that could result in adverse health effects.
|This determination represents a professional judgement based on critical data which ATSDR has judged sufficient to support a decision. This does not necessarily imply that the available data are complete; in some cases additional data may be required to confirm or further support the decision made.||Evaluation of available relevant information* suggests that, under site-specific conditions of exposure, long-term exposures to site-specific contaminants (including radionuclides) have had, are having, or are likely to have in the future, an adverse impact on human health that requires one or more public health interventions. Such site-specific exposures may include the presence of serious physical or safety hazards.|
|C. Indeterminate Public Health Hazard
This category is used for sites in which "critical" data are insufficient with regard to extent of exposure and/or toxicologic properties at estimated exposure levels.
|This determination represents a professional judgement that critical data are missing and ATSDR has judged the data are insufficient to support a decision. This does not necessarily imply all data are incomplete; but that some additional data are required to support a decision.||The health assessor must determine, using professional judgement, the "criticality" of such data and the likelihood that the data can be obtained and will be obtained in a timely manner. Where some data are available, even limited data, the health assessor is encouraged to the extent possible to select other hazard categories and to support their decision with clear narrative that explains the limits of the data and the rationale for the decision.|
|D. No Apparent Public Health Hazard
This category is used for sites where human exposure to contaminated media may be occurring, may have occurred in the past, and/or may occur in the future, but the exposure is not expected to cause any adverse health effects.
|This determination represents a professional judgement based on critical data which ATSDR considers sufficient to support a decision. This does not necessarily imply that the available data are complete; in some cases additional data may be required to confirm or further support the decision made.||Evaluation of available relevant information* indicates that, under site-specific conditions of exposure, exposures to site-specific contaminants in the past, present, or future are not likely to result in any adverse impact on human health.|
|E: No Public Health Hazard
This category is used for sites that, because of the absence of exposure, do NOT pose a public health hazard.
|Sufficient evidence indicates that no human exposures to contaminated media have occurred, none are now occurring, and none are likely to occur in the future|