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HEALTH CONSULTATION

ACRE MIDDLE SCHOOL SITE
(a/k/a FORMER COLONEL GAS PROPERTY
LOWELL, MIDDLESEX COUNTY, MASSACHUSETTS


BACKGROUND AND STATEMENT OF ISSUES

The City of Lowell, Massachusetts provided ATSDR with the results from environmental sampling conducted at the "Acre Middle School Site." The City plans on building a 600 student middle school on the property, and has requested that the Agency for Toxic Substances and Disease Registry (ATSDR) determine if contamination will pose a public health threat based on future use of the site [1]. A clean-up action is planned to address environmental contamination at the site [2].

The Acre Middle School Site is approximately 6.45 acres located in a mixed commercial/industrial and residential area. Numerous commercial and industrial facilities have been located on the site dating back to the 1800's [2]. The former Colonial Gas property is located immediately adjacent and west of the proposed school site [2]. In addition, a portion of the former Colonial over laps on to the Acre Middle School site [2]. Currently, the site is partially fenced, and much of the site is either paved or covered with buildings [3]. The population near the site is served by a public water system.

Environmental sampling at the Colonial Gas site, and later at the Acre Middle School site, began in the mid 1980s [2]. The latest and most comprehensive sampling at the site occurred from July 2000 to September 2001 as part of a Phase II/III investigation. Soil and ground water samples were collected and analyzed for volatile organic compounds (VOCs), semi-volatile compounds (semi-VOCs), and inorganic compounds.

Phase II/III Sampling Results

Soil sampling on site identified areas containing elevated levels of polycyclic aromatic hydrocarbons (PAHs) and metals in the surface and subsurface soils. PAHs(1) were detected up to 33 parts per million (ppm) in the surface soil (Sample CG-OD-7-0-2), and 86 ppm in the subsurface soil (Sample OP-SB3-4-6) [2]. Lead was detected in the surface soil and subsurface soil at a maximum concentration of 9,900 ppm (Sample OP-MW3-0-2) and 21,000 ppm (Sample OP-SB16-2-4), respectively [2]. Arsenic was detected up to 51 ppm in the surface soil (Sample OP-MW3-0-2). The VOCs measured in the soils on site were low, and ranged from the parts per billion (ppb) to the low ppm range [2].

Samples collected from the groundwater monitoring wells on site showed very low levels of VOCs. The majority of the samples collected from the groundwater were below the analytical detection limit, with a few samples detecting VOCs in the low ppm range. Cyanide was detected in several groundwater monitoring wells on the southern portion of the site[3].


DISCUSSION

ATSDR was requested to assess the contamination at the site with respect to future development of the site as a school. Since ATSDR does not have the plans for the future development for the site, to include locations of playgrounds and other high concern exposure points, conservative assumptions were made regarding potential exposure scenarios.

Environmental testing of surface and subsurface soil identified elevated levels of PAHs and lead. Potentially exposed populations in the future will include children attending the middle school, adult workers, visitors, and nearby residents. Exposure to contaminants from the site are likely to occur from direct contact with the soil and/or dust. Ingestion of soil, particularly by children, is likely to result in the highest level of exposure. Inhalation of contaminated dust would also contribute to the overall exposure to contamination at the site. Inhalation and/or ingestion of VOCs are not of concern at this site since VOC concentrations measured in both the soil and groundwater are low. In addition, area residents do not utilize the groundwater as a potable water source. At the low concentrations detected in the soil and groundwater, the VOC's are unlikely to pose a future inhalation threat by migrating and accumulating in a building space.

The contaminants of concern regarding future development of this site as a school are the lead, and to a lesser degree, PAHs. Lead was detected at a maximum concentration of 9,900 ppm in the surface soil, and 21,000 ppm in the subsurface soil. Elevated levels of lead in soil can pose a health threat, particularly to children. Children are more likely to ingest larger amounts of soil relative to body weight, and have developing nervous systems that are susceptible to the deleterious effects of lead [4]. The Centers for Disease Control and Prevention (CDC) has reported that blood lead levels in young children have been raised, on average, about 5 micrograms per deciliter (µg/dL) for every 1,000 ppm of lead in soil or dust, and may increase 3 to 5 times higher than the mean response depending on play habits and mouthing behavior [5]. Blood lead levels of 10 µg/dL and above have been associated with adverse health effects such as developmental and hearing impairment, and reductions in intelligence quotient (IQ) in children [4,5]. Children attending the middle school, and children from nearby residential areas may come in contact with the soil while playing on the school grounds. The contaminated soil can also be tracked home on the shoes potentially exposing other members of the family.

The PAHs detected at the site also pose a concern, but to a much lesser degree than the lead. The PAHs are a group of chemicals that are formed during the incomplete burning of coal, oil, gas, wood, garbage, or other organic substances. There are more than 100 different PAHs. In general, they occur as complex mixtures (for example, as part of combustion products such as soot), not as single compounds. You may be exposed to PAHs in the soil at sites such as this one, where a former manufactured-gas facility operated. PAHs are, for the most part, readily metabolized and eliminated. The acute toxicity of PAHs is relatively low. For example, a dose of 1 milligram of benzo(a)pyrene (the most toxic PAH) per kilogram body weight (mg/kg) is a No-Adverse Effect-Level (NOAEL) in animals and humans [6]. To receive a dose numerically equivalent to this NOAEL, a 10-kg child would have to consume daily 5,000 mg of soil containing 2,000 ppm benzo(a)pyrene. Such a scenario is very unlikely. Inhalation of complex PAH mixtures (e.g., cigarette smoke, roofing tar or coal tar pitch volatiles, and coke oven emissions) may cause cancer in humans, but the doses required are typically high and of long duration. In summary, the PAH levels may pose some risk to health, but it is likely to be minimal. The clean-up action planned for this site should further reduce the risk from exposure to PAHs.


CHILD HEALTH INITIATIVE

ATSDR considers the unique susceptibility of children in the evaluation of all hazardous waste sites. Children may have higher levels of exposure since they are more likely to inhale and ingest contaminated soil. Infants and toddlers are also more susceptible to the adverse effects of some contaminants which must be considered when assessing exposure to environmental contaminants. Since children are particularly susceptible to the deleterious effects of lead, a major contaminant at this site, recommendations were provided at this site to ensure that children are protected from future exposure.


CONCLUSIONS

Based on the future use of the site as a school, ATSDR concludes the following:

  1. The levels of lead detected in the soil, and to a lesser extent, the PAHs, pose a "Public Health Hazard" for future use of the site as a school.

  2. The contamination in the groundwater does not pose a health threat since (1) the residents near the site do not receive there drinking water from private wells, and (2) VOC concentrations are low, and unlikely to migrate into buildings at sufficient concentrations.

RECOMMENDATIONS

None.


PREPARERS OF REPORT

Prepared by:

Tim Walker, MS, RS, CIH
Environmental Health Specialist
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation

Reviewed by:

Susan Moore, Chief
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation


REFERENCES

  1. Letter from the City of Lowell to Gary Perlman, ATSDR Region One Representative, December 6, 2001.

  2. Release Abatement Measurement Plan, 294 School Street, Lowell, Massachusetts, TRC, November 2000.

  3. E-mail comments on Acre Middle School Site Draft Health Consultation from Gary Perlman, ATSDR Region I Representative, April 18, 2002.

  4. Toxicological Profile for Lead, Update, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, April 1993.

  5. Preventing Lead Poisoning in Young Children, A Statement by The Centers for Disease Control - October 1991, U.S. Department of Health and Human Services, Public Health Service.

  6. Toxicological Profile for Polycyclic Aromatic Hydrocarbons (PAHs) Update, U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry, August 1995.

1. PAHs were converted to benzo (a) pyrene equivalents using a weighted toxicity equivalent factor (TEF) approach.


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