HEALTH CONSULTATION
BIG BEAVER FALLS SCHOOL SITE
BEAVER FALLS, BEAVER COUNTY, PENNSYLVANIA
The Pennsylvania Department of Environmental Protection (PADEP) asked the Pennsylvania Department of Health (PADOH) and the Agency for Toxic Substances and Disease Registry (ATSDR) to evaluate preliminary environmental data from the Big Beaver Falls School Site (site) and determine if the site poses a health hazard to students, faculty, and visitors. Lead, arsenic, antimony, and benzo(a)pyrene were detected in surface soil (0-2 feet) at maximum concentrations of 2,540 milligrams per kilogram (mg/kg), 237 mg/kg, 36.4 mg/kg, and 3.2 mg/kg, respectively. There is no exposure to contaminated groundwater beneath the site. The site is used for outdoor athletic field events (practices) and receives occasional visitors from the community.
Based upon preliminary data, the site does not appear to pose a public health threat to students, faculty, visitors, and the community at large under a school use scenario of 180 days per year. Over the next few years, the school district plans to make certain improvements to the property, including filling and regrading the site with clean soil to construct new baseball and football fields. If completed, that action will reduce or eliminate future exposure to contaminated soil on the site.
BACKGROUND AND STATEMENT OF ISSUES
The Big Beaver Falls School Site is on 8th Avenue at 16th Street adjacent to the Big Beaver High School in Beaver Falls, Pennsylvania (Figures 1 and 2). The 30- acre site consists of several properties the school district wishes to improve or expand, including the former elementary school, the middle school, and high school athletic fields (Figure 3). The site is bounded by residential and industrial development to the north, east and south, and a creek (Walnut Bottom Run) and railroad tracks to the west (Figure 3). According to the 2000 census, Beaver Falls has a population of 9,920 [1]. The schools have a combined total enrollment of 1,291 students, and the schools and the rest of the town are served by a state approved public water supply.
From the early 1900s to the late 1970s, the site was used by the school as well as a variety of industrial enterprises. Some included a chemical company (acid works), an asbestos protected metal company, a septic tank company, a scrap yard, and a drilling company [2](Figure 4). Since the completion of the new high school in the 1980s, the site has been used only by the school and occasional site visitors. The past industrial uses have contaminated on-site soil and groundwater, and now there is a potential exposure risk to students and others, particularly through the soil where the proposed football field is to be constructed in the southwestern portion of the site (Figure 4).
As part of the school's expansion project, the former elementary school building, now empty, will be structurally connected to the middle school and renovated for future occupancy. According to PADEP, the best estimate of a time frame for project completion, is two to three years. The contractor inadvertently discovered contaminated surface (0-2 feet) soil (lead to 2,540 mg/kg, arsenic to 237 mg/kg, antimony to 36.4 mg/kg, benzo(a)pyrene to 3.2 mg/kg) when, as part of the general (Phase 2) site investigation, he was trying to determine potential hazards to work crews. Reported contaminant levels are based on a preliminary, non-comprehensive soil sampling effort. Still, surface soil does not appear to be contaminated at levels of health concern over the entire site. Soil was collected in discrete, 2-foot composite samples at each sampling point. Lead, for example, was detected in only 2 of the 11 samples (SB-11 and SB-13, Figure 4), and benzo(a)pyrene in only one. SB-11 and SB-13 (where the highest arsenic concentration was detected) are outside the boundaries of both proposed playing fields. The proposed football field site and the land immediately surrounding it (Figure 4) have been owned and used by the school district since construction of the middle school over 65 years ago. Therefore, an exposure risk from recreational use may have existed there (apparently unknown to anyone) for that entire time. Students from kindergarten through grade 12 use the property during the months when school is in session. Currently the field is used for soccer, football, and other practices, but not for officially scheduled games.
Given the above circumstances, the PADEP asked ATSDR and PADOH to evaluate the site and determine if the intended use poses a health hazard to students, faculty, and occasional site visitors.
On October 11 and 12, 2001, J. E. Godfrey of PADOH visited the site, the latter visit with a PADEP representative. On October 11 (afternoon), the athletic fields were buzzing with activity and a full dress football practice was underway. The perimeter of the practice field is bounded by an 8-foot high chain link fence, but it is breached in at least one place along the west (back) side and provides no real security.
On the morning of October 12, the PADEP representative pointed out monitoring well and soil boring locations. The present topsoil is only a few inches thick, and in some places the subsurface fill material (concrete, rocks, and stumps) is directly exposed. The school district plans to fill and grade the area with clean topsoil so that new baseball and football fields can be constructed (Figure 4). That action will lessen or remove the current risk of exposure to lead, arsenic, and other contaminants in the existing surface soil. Because no one consumes or bathes in the groundwater beneath the site, heavy metal contamination in that medium (e.g. cadmium at 494 micrograms/liter (µg/L) is not a health concern and will not be discussed in this document.
In this section, PADOH discusses the effects that may occur in persons exposed to site-related contaminants. The ATSDR has developed health-based comparison values (CVs) that are chemical-specific concentrations, which determine environmental contaminants of health concern. We use CVs to determine which contaminants require further evaluation. These CVs include Environmental Media Evaluation Guides (EMEGs), and Reference Dose Media Evaluation Guides (RMEGs) for noncancerous health effects. If environmental media guides cannot be established because of a lack of available health data, other CVs, such as those from the U.S. Environmental Protection Agency (EPA), may be used to select a contaminant for further evaluation. While media concentrations less than a CV are unlikely to pose a health threat, media concentrations above a CV do not necessarily represent a health threat. Therefore, CVs should not be used as predictors of adverse health effects or for setting cleanup levels.
Lead was detected in only 2 out of 11 surface soil samples tested on the site. Lead levels in those samples (2,540 mg/kg, 1,620 mg/kg) were above the 400 mg/kg screening level used by EPA. To properly assess the human health threat associated with exposure to contaminated soil, it is important to have the shallow surface soil (0-3 inches) data. Since we do not have that data, we will use the maximum level of lead detected in the 0-2 feet interval, e.g., 2,540 mg/kg.
Although lead is a concern for adults, children are particularly susceptible to adverse health effects from lead exposure. Present scientific information suggests that blood lead levels of 10 to 25 micrograms per deciliter (ug/dL) may be related to delayed mental development, reduced intelligent quotient (IQ) scores, impaired hearing, and poor attention span.
To determine if the levels of lead are a concern at this site, we evaluated the potential exposure based on a recreational use scenario. We assumed that students are on the field for two hours per day, 180 days per year for 13 years. PADOH calculated a conservative oral reference dose estimate that corresponds to a residential exposure to 400 mg/kg of lead in soil, and using that as a screening value, compared it to potential recreational oral exposure. Dermal exposure and inhalation of fugitive dust are unlikely to contribute significantly to the hazard represented by ingestion of soil.
The estimated exposure for a child (15 kg) under the above described scenario is 0.00139 mg/kg/day. This is about 3.6 times lower than the level considered protective of public health. The estimated exposure for an adult (70 kg) is 0.000149 mg/kg/day. This is also about 3.6 times lower than the level considered protective of public health. The level of lead in the soil from preliminary sampling data, therefore, does not appear to pose a public health threat for the intended use of the site.
In general, the concentration of arsenic in soil varies widely across the United States, ranging from about 1 to 40 mg/kg, with an average value of about 5 mg/kg (4). At the site, arsenic is also variable, from a low of 12.5 mg/kg to a high of 237 mg/kg (Figure 4). However, soils near arsenic-rich geological deposits, some mining and smelting sites, or agricultural sites where arsenic pesticides were applied, may contain higher levels of arsenic.
Skin lesions appear to be the earliest observable sign of chronic exposure to arsenic (4). Arsenic is recognized as a human carcinogen by the U. S. Department of Health and Human Services and the World Health Organization's International Agency for Research on Cancer. The EPA also classifies arsenic as a human carcinogen.
ATSDR has developed a chronic oral minimal risk level (MRL) of 0.0003 mg/kg/day for non-cancerous health effects based on epidemiologic studies that demonstrate skin lesions in people exposed to arsenic. Doses below the MRL are not likely to cause any non-cancerous adverse health effects. Doses above the MRL require further evaluation to determine if adverse effects are likely to occur.
If children (15 kg) were to be exposed to arsenic in the school scenario described above at the maximum soil concentration (237 mg/kg), then the estimated exposure dose would be 0.000129 mg/kg/day, which is about 2.3 times lower than ATSDR's chronic oral MRL. If adults were to be exposed to arsenic, then the estimated oral exposure dose would be 0.0000139 mg/kg/day, which is about 22 times lower than ATSDR's chronic MRL. Therefore, exposure to arsenic for a school use scenario is unlikely to cause any non-cancerous adverse health effects either for children or adults.
To evaluate the possible cancer risk associated with ingestion of arsenic contaminated soil, we calculated the theoretical cancer risk using EPA's Cancer Slope Factor (CSF) of 1.5 (mg/kg/day) -1 for arsenic. PADOH evaluated the cancer risk associated with exposure to arsenic for 13 years at 3.8x10-6, or a likely increase of about 4 cancers in 1,000,000 people. The cancer estimate was calculated using conservative assumptions about frequency and duration of site use previously stated. It is unlikely, however, that a person will be in contact with the highest level of arsenic contaminated soil over an entire school career, even if he plays on the site every school day. Based upon existing data, it appears that the current levels of arsenic do not pose a significant health threat for recreational use of the site. However, because arsenic is a human carcinogen, exposure to it should be eliminated or reduced to the lowest level possible.
Antimony concentrations were not above any CVs, so that chemical will not be discussed further.
Benzo(a)pyrene (B[a]P) was detected in only one soil sample at a maximum concentration of 3.5 mg/kg. B(a)P is a member of a group of chemicals known as polycyclic aromatic hydrocarbons (PAHs). PAHs are formed during the incomplete burning of coal, oil, garbage or other organic substances.
In humans, non-cancerous health effects that may result from eating or drinking foods containing low levels of B(a)P are unknown. ATSDR has not developed an MRL and EPA has not developed a reference dose. Existing studies in animals suggest that exposure doses at very high levels (several orders of magnitude above those at the site) are necessary to cause non-cancerous adverse health effects. Therefore, the level found in only one sample on site is unlikely to cause such effects.
B(a)P is classified as a probable human carcinogen by EPA, the Department of Health and Human Services, and the International Agency for Research on Cancer. If people ingest soil contaminated with B(a)P at 3.5 mg/kg under the school use scenario previously stated, there will be no significant increased cancer risk.
ATSDR and PADOH recognize that infants and children may be more sensitive to exposures than adults in communities with contamination in water, soil, air, or food. This sensitivity is a result of a number of factors. Children are more likely to be exposed because they play outdoors and they often bring food into contaminated areas. Children are shorter than adults, which means they breathe dust, soil, and heavy vapors close to the ground. Children are also smaller, resulting in higher doses of chemical exposure per body weight. The developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. Most importantly, children depend completely on adults for risk identification and management decisions, housing decisions, and access to medical care. Therefore, ATSDR and PADOH are committed to the special interests of children, and have evaluated child-specific scenarios at the Big Beaver Falls School Site.
Based upon the site preliminary data submitted for review, PADOH and ATSDR conclude that the site poses no apparent public health hazard to students, faculty, and occasional site visitors under a school use scenario of 2 hours per day for 180 days per year for 13 years. The school district plans to fill and grade the practice fields with clean soil which, if accomplished, will reduce or eliminate existing risks of exposure to contaminated soil.
Sample the on-site soil for hazardous chemicals at a depth of 0 to 3 inches. At PADEP's request, PADOH and ATSDR will evaluate those samples to make a final determination as to whether the site poses a health hazard through that medium.
The PADEP and PADOH will present the conclusions of this health consultation to the Big Beaver School District Administration. Should the Administration request it, PADEP and PADOH will present the conclusions to the community at large in an appropriate format, such as a public meeting or through printed materials.
1. United States Census Bureau. Census 2000.
2. Pennsylvania Department of Environmental Protection. August, 2001. Site Investigation Report, Big Beaver Falls School District, Beaver Falls, Beaver County, Pennsylvania.
3. Commonwealth of Pennsylvania. 1995. Land Recycling and Environmental Remediation Standards Act (Act 2).
4. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Arsenic (Update), U.S. Public Health Service. Atlanta, Georgia: ATSDR, September 2000.
J. E. Godfrey, P.G.
Licensed Professional Geologist
Pennsylvania Department of health
This Health Consultation for the Big Beaver Schools Site was prepared by the Pennsylvania Department of Health (PADOH) under a cooperative agreement with the federal Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the health consultation was initiated.
Roberta Erlwein
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation (DHAC), ATSDR, has reviewed this health consultation and concurs with its findings.
Lisa C. Hayes
for Richard E. Gillig
SectionChief, SPS, SSAB, DHAC, ATSDR
Figure 4. Constituents in Surface Soil
