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PUBLIC HEALTH ASSESSMENT

GRAND STREET MERCURY SITE
HOBOKEN, HUDSON COUNTY, NEW JERSEY


ENVIRONMENTAL CONTAMINATION AND OTHER HAZARDS

The data in this section list the site contaminants of concern. ATSDR and NJDHSS evaluate these contaminants in the subsequent sections of the Public Health Assessment to determine whether exposure to them has public health significance. ATSDR and NJDHSS select and discuss these contaminants based upon the following factors:

  1. Concentrations of contaminants on and off the site.
  2. Comparison of on-site and off-site concentrations with health assessment comparison values for (1) non-carcinogenic endpoints and (2) carcinogenic endpoints.

Comparison values for Public Health Assessments are contaminant concentrations in specific media that are used to select contaminants for further evaluation. EPA's Reference Dose (RfD) and Reference Concentration (RfC) are estimates of the daily exposure to a contaminant that is unlikely to cause adverse health effects. The environmental contamination section includes sampling data from a variety of media sources including: soil; air; and building. Contaminants of concern are selected by comparing contaminant levels detected at the site to public health assessment comparison values. Selected contaminants are further evaluated in subsequent sections of the Public Health Assessment to determine whether exposure to these contaminants are likely to result in harmful health effects in humans.

A. On-site Contamination

    Soil

In April 1996, USEPA collected on-site soil samples from the parking lot and sediment samples from the building to determine the nature and extent of mercury contamination. Mercury was detected in every soil sample at concentrations ranging from 0.77 to 290 milligrams of mercury per kilogram of soil (mg/kg). The highest concentrations of mercury were detected next to the building. The USEPA also collected sediment samples from floor drains and sump pits in the basement of the building. The results indicated presence of mercury in all of the floor drains and sump pits, ranging in concentrations from 36 to 2,540 mg/kg.

    Air Monitoring in Buildings

Using a Jerome Model 411-X portable mercury analyzer, a private consultant (Enpak Services) surveyed the building in March 1995. The analytical range of the instrument was between 0.001-0.888 mg/m3. Detectable levels of mercury vapors were found on floors 3, 4, and 5. In breathing zone areas, the highest level of mercury detected was 0.005 mg/m3 (fifth floor); in source areas, the highest level of mercury was 0.888 mg/m3, which was found in the subflooring of a fifth floor unit.

On December 22, 1995, NJDHSS officials conducted a site visit to the 722 Grand Street building. During the visit, a survey of mercury vapors was performed during the visit using a Bacarach Mercury Vapor Analyzer. Surveying was performed on floors 3, 4, and 5. The maximum levels of mercury vapor detected for floors 3, 4, and 5 were .01 mg/cubic meter, 0.045 mg/cubic meter, and 0.050 mg/cubic meter, respectively (instrument detection limit: 0.01 mg/cubic meter) indicating the presence of mercury vapor at levels of public health concern.

On December 27,1995, using a Jerome 431 Mercury Vapor Analyzer, USEPA staff surveyed 15 units, the attached townhouse, and hallways on each floor. Air concentrations of mercury were measured at several locations in each unit at a height of 6 inches and 5 feet above the floor. Detectable levels of mercury vapor (up to 0.013 mg/m3) were found in 9 apartment units. Detectable concentrations of mercury were not found in the hallways. USEPA personnel observed two separate puddles of mercury on a tar layer in the subflooring of a fifth floor apartment unit.

The USEPA initiated periodic air monitoring throughout the building in January 1996, which is on-going. Almost 2,000 air samples have been collected, and approximately seventy percent of those samples identified mercury in air throughout the main building and townhouse. The concentrations of mercury in air ranges from nondetect to 0.3 mg of mercury per cubic meter of air.

    Sampling of Building Structures

The USEPA used X-Ray Fluorescence technology to identify the extent to which mercury may have penetrated wooden components in the roof and wooden support beams in three condominium units. The results indicated mercury contamination ranging from 0.790 to 6,300 mg/kg, throughout these structural components. The USEPA also used X-Ray Fluorescence technology to identify the extent to which mercury may have penetrated exposed brick walls. The USEPA collected samples from 14 locations on the fourth and fifth floors. The results indicated mercury contamination ranging from 39.8 to 9,110 mg/kg, throughout these structural components.

B. Off-Site Contamination

    Soil

The USEPA collected soil samples from a residential yard and basement adjacent to the GSMS. The average concentration detected was below USEPA's residential risk-based concentration standard of 23.5 mg/kg (ranging in concentrations from 5.5 mg/kg to 30.4 mg/kg).

C. Physical and Other Hazards

On-going actions by USEPA have secured and stabilized the site. To address physical hazards on-site, USEPA has boarded and/or secured all points of access to the building.


PATHWAYS ANALYSIS

To determine whether nearby residents or residents at the site are exposed to site related contaminants, ATSDR/NJDHSS evaluate the environmental and human components that lead to human exposure. This pathways analysis consists of five elements: (1) a source of contamination; (2) transport through an environmental medium; (3) a point of human exposure; (4) route of human exposure; and (5) an exposed population. The ATSDR/NJDHSS classify exposure pathways into three groups: (1) "completed pathways", that is, those in which exposure has occurred, is occurring, or will occur; (2) "potential pathways", that is, those in which exposure might have occurred, may be occurring, or may yet occur; and (3) "eliminated pathways", that is, those that can be eliminated from further analysis because one of the five elements is missing and will never be present, or in which no contaminants of concern can be identified. A summary of the pathways for the GSMS are discussed below. See Table I .

A. Completed Exposure Pathways

    Past Residential Air Pathway

Air monitoring in the building has indicated the presence of elevated concentrations of mercury. In addition, pools of elemental liquid mercury have been observed under floor boards on the fifth floor, which indicates that there is a substantial reservoir of mercury in the building. Site data and information indicate that a completed exposure pathway via inhalation did exist at the GSMS in the past. Currently this pathway is interrupted as residents have been relocated.

Table I. Completed Exposure Pathways

EXPOSURE PATHWAY ELEMENTS TIME
SOURCE ENVIRONMENTAL
MEDIA

 

POINT OF
EXPOSURE

 

ROUTE OF
EXPOSURE

 

EXPOSED
POPULATION

 

GSMS
Air
Indoors
residences)

Inhalation

Residents
Past


PUBLIC HEALTH IMPLICATIONS

A. Toxicological Evaluation

    Introduction

In this section, NJDHSS will discuss the health effects in persons exposed to specific contaminants. To evaluate health effects, ATSDR has developed a Minimal Risk Level (MRL) for contaminants commonly found at hazardous waste sites. The MRL is an estimate of daily human exposure to a contaminant below which non-cancer, adverse health effects are unlikely to occur. MRLs are developed for each route of exposure, such as ingestion and inhalation, and for the length of exposure, such as acute (less than 14 days), intermediate (15 to 364 days), and chronic (greater than 365 days). ATSDR presents these MRLs in the Toxicological Profiles. These chemical-specific profiles provide information on health effects, environmental transport, human exposure, and regulatory status. In the following discussion, NJDHSS used ATSDR Toxicological Profiles for the contaminants of concern at the site. The NJDHSS will use a USEPA Reference Concentration (RfC) as a health guideline, when a MRL is not available.

    Air Exposure

Indoor air mercury levels in the breathing zone ranged from non-detectable to 0.05 mg/m3. At other residential properties contaminated with mercury, ATSDR has recommended that indoor air mercury levels should be below 0.0003 mg per cubic meter in order to protect human health. Mercury levels above 0.0003 mg/m3 exceed ATSDR's chronic Minimal Risk Level (MRL) and EPA's Reference Concentration (RfC). Therefore, indoor air levels in the breathing zone at the Grand Street property exceed an acceptable level. At floor level, where children might crawl and play, mercury levels were even higher. Gross mercury contamination inside the 722 Grand Street building is the likely source of mercury exposure, with exposures occurring primarily by inhalation of contaminated indoor air.

B. Health Outcome Data Evaluation

Associations between urinary mercury levels and health effects have been studied in adults with occupational exposures to mercury. Urine mercury concentrations of 20-100 µg/L may be associated with subtle neurological changes, even before overt symptoms occur. Early signs and symptoms of exposure to mercury might include decreased responses on tests of nerve conduction, brain-wave activity, and verbal skills. Urine concentrations of mercury in unexposed adults were less than 20 µg/L. This level was exceeded by 69% of the residents of the building, which indicates that they were being exposed to levels of mercury of health concern. Based on the elevated urine mercury levels, ATSDR offered clinical evaluations to building residents at the Environmental and Occupational Health Sciences Institute (EOHSI) Clinical Center in Piscataway, New Jersey. These evaluations included medical testing and follow-up urine mercury analyses. Individual results are confidential and were provided only to the participants.

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