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PETITIONED PUBLIC HEALTH ASSESSMENT

NEWTOWN COMMUNITY
GAINESVILLE, HALL COUNTY, GEORGIA


SUMMARY

The Agency for Toxic Substances and Disease Registry (ATSDR) was petitioned to evaluate health concerns of residents living in the Newtown Community in Gainesville, Georgia. The petition was filed by the Newtown Florist Club, a 50 year old organization in the Newtown community. Area residents expressed concern over high rates of cancer, lupus and respiratory diseases that community members believe may be caused by emissions from nearby industrial facilities and the location of the community over a landfill.

Residents have concerns regarding past air emissions and their potential impact on past, current, and future health conditions. As a result, ATSDR evaluated outdoor air concentrations of pollutants collected by the state from an air monitor at the Fair Street Elementary School in 1997 and simulated historical air concentrations based on available data and air modeling. The air monitor data were analyzed in a previous public health assessment, released final on March 15, 2001 [1]. The March 2001 public health assessment also addressed groundwater, soil, and biological issues. Simulated historical air concentrations and measured particulate concentrations are evaluated in this public health assessment.

ATSDR based its modeling on historical information collected from the Environmental Protection Agency's (EPA) Toxic Release Inventory (TRI) and air permit files. In addition, ATSDR evaluated two nationwide air models generated by EPA in 1990 and 1996, which estimated emissions and concentrations of hazardous air pollutants in different areas of the United States. These estimates were used to calculate a hypothetical cancer risk and non-cancer hazard in the Newtown Community.

ATSDR reviewed air pollutant emissions and air data between 1983 and 1998 in the Newtown community. Hazardous air pollutants present in the community are the result of emissions to the atmosphere from stationary sources (e.g. manufacturing plants) and mobile emissions (e.g., car, trucks, and lawn equipment). Many of the more toxic contaminants identified in this evaluation are a product of mobile emissions in Newtown. This is a common problem in urban areas throughout the United States.

The estimates of modeling historical air emissions in this document are limited. Older historical emission rates and potential exposures could not be evaluated because TRI emissions data are only available from 1986 to present. Facility air permit records were also somewhat limited and are available from 1983 to present. Many residential concerns are about exposures that occurred previous to this time period. ATSDR is unable to make conclusions about the risk of adverse health effects that may occur as a result of exposure to emissions previous to these dates.

ATSDR does not expect a noticeable increase in cancer from exposure to modeled or measured levels of hazardous air pollutants in ambient air in the Newtown community. However, other respiratory effects may be experienced by residents from the air quality in the south side of Gainesville. Respiratory health is probably most impacted by mobile emissions in the community.


SITE DESCRIPTION AND HISTORY

Introduction

On April 10, 1995, a member of the Newtown Florist Club petitioned the Agency for Toxic Substances and Disease Registry (ATSDR) to investigate the potential public health impact of combined industrial emissions on the Newtown Community [2]. A finalized version of a public health assessment was released to the public on March 15, 2001. The purpose of the health assessment was to identify potential human exposures and to recommend appropriate public health follow-up activities. ATSDR evaluated community concerns and available soil, methane gas, groundwater, tap water, stormwater runoff, air, and biological data and determined the potential and extent of residential exposure to environmental contamination. Recent environmental data do not suggest a threat to human health. Moreover, the environmental ambient air data may not have been representative of community exposures. ATSDR recommended further evaluation of particulate concentrations in ambient air; potential past exposures to industrial emissions; and whether or not the current ambient air monitor is in an optimal location for measuring community concentrations of air pollutants. This document evaluates the follow-up to these recommendations.

Background

Newtown is a residential area located in the southeastern section of Gainesville, Hall County, Georgia. Before 1936, the area currently known as Newtown was reported to be the site of the Gainesville/Hall County landfill. In 1936, a tornado passed through the community and destroyed many homes. Debris from the tornado were disposed of in the landfill, the fill materials were burned, and the landfill was covered with soil. No records of the landfill existing before the 1936 tornado can be found, and the landfill does not exist in city planning maps dated 1930. Approximately 75 homes were rebuilt on top of the debris landfill and the surrounding area with federal Reconstruction Finance Corporation loans within a few years following the tornado [3,4].

The Newtown Community is located in an industrial and commercial area of Gainesville, Georgia. Within three miles of the community, there are 14 facilities required to report to the TRI, and 56 additional businesses that are regulated by EPA because they handle, store, or use hazardous materials [5]. The area directly south of Newtown is zoned heavy industrial. To the east and west, properties are zoned as a mixture of general business, light industrial, and residential; the properties include a number of businesses, restaurants, and industries. To the north of the community, properties are zoned as residential. A railroad track borders the community to the south/southeast and provides rail access to the many facilities in the area. The railroad track is within 20 feet of the community playground. There is a hospital and a school within 0.25 miles of the community. For maps of the community, refer to Appendix A.

Demographics

Newtown is a community consisting of a 10 block area with 143 households and a population of 350. The community is predominately African-American. The median age is about 5 years older than the median age for the county (40.2 and 35 years of age, respectively). The area appears to be relatively stable in that the median length of residence is over 18 years, in contrast to the county which has a median length of residence of 9.7 years [6-9]. For additional demographic information, see Appendix B.

Community Health Concerns

Specific health concerns expressed by Newtown residents were related to exposure to toxic emissions, discharges, and fallout from surrounding industries. Residents believe a number of health conditions in the community may be attributable to industrial emissions, including lupus, cancer, kidney failure, respiratory ailments such as chronic bronchitis and asthma, and heart conditions. The community was built over a landfill in 1936, and residents have concerns about exposure to contamination from landfill soils and gases [1]. In addition, a junkyard nearby is a source of concern for many residents who believe stormwater runoff from the site may be contaminating community soils with metals, oil, grease, and gasoline. Residents have also expressed concern about lead contamination of their homes and drinking water. Finally, for a number of years, residents noticed a fine dust that settled on houses and cars that could have been attributed to two different facilities located within one-tenth of a mile from the community. They believe exposure to this dust has compromised their respiratory health.

The ATSDR Public Health Assessment, dated March 31, 2001, addressed these community concerns except for past industrial emissions and dust which are addressed here.


DISCUSSION

Discussion Section 1: General Information Regarding Ambient Air and Health

Contaminants in Air

Chemical contaminants and particulates are introduced into air through both natural and man-made processes. Sometimes, the same contaminants can be present in air from both processes. For instance, carbon dioxide is a natural component of air and is also produced through human processes. Particulates in ambient air can also be naturally occurring or the by-product of human processes.

Hazardous air pollutants (HAPs) have been defined by law to include 189 toxic air pollutants that are emitted by a variety of industrial sources and motor vehicles. In general, hazardous air pollutants can include all toxic air pollutants. Hazardous and toxic air pollutants are generally defined as those pollutants that are known or suspected to cause cancer or other non-cancer health effects.

Toxic air pollutants may exist as particulate matter (airborne dust) or as gases. Toxic air pollutants include metals which are normally attached to small particles that are suspended in air and organic compounds that are present in the air as a gas or adsorbed on to particles. An example is benzene, which is in gasoline [10, 11].

An exposure assessment of air pollution requires the identification of the pollution sources and the types of pollutants emitted, information on the movement of the pollution in the air, and location of people in relation to contaminant sources.

Potential Sources of Air Pollution

Outdoor Sources

There are a number of outdoor sources of air contamination and pollution. These sources include: industrial, commercial, mobile (on and off road), agricultural, and sources that are naturally occurring.

Table l: Examples of Outdoor Pollution Sources

Sources of outdoor pollution Examples
industrial facility stack emissions and point emissions
commercial dry cleaner emissions, beauty parlors, auto shops, house painting, roofing, and asphalt paving
mobile automobiles, airplanes, buses, construction equipment, lawn mowers, leaf blowers, trains
agricultural pesticide spraying, plowing, windblown dusts
natural radon gas, naturally occurring metals in air, methane gas

Indoor Sources

In addition to outdoor sources, people can be exposed to indoor air pollutants sources. Sometimes the levels of air pollution indoors is higher than the levels outside. In a recent study, the average levels of benzene exposure, was three times as high indoors as outdoors [12]. Its chief source was cigarette smoke, the greatest source of indoor pollutants. Other major sources of indoor air pollution include incomplete combustion from cooking and heating systems, household deodorizers, dry-cleaned clothes, air fresheners and cleaners, insect repellents and treated and manufactured wood and wood products. Some of these sources emit polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds, which are known carcinogens [12]. Examples of indoor sources of air pollution are illustrated in the table below.

Table 2: Examples of Indoor Pollution Sources

Sources of indoor pollution Examples
combustion smoking, cooking, fireplaces, heating the house
particle resuspension dusting, vacuuming, sweeping, beating rug
hobbies model cars, woodworking, painting
consumer products home cleaning agent fumes, home pesticides, particle boards glues used in furniture
building materials fiberglass or asbestos insulation, carpet
heating fireplaces, natural gas, gas dryers
natural radon

Personal exposure to indoor air contaminants depends on the amount of time a person spends inside their house, the concentrations of contaminants present in the home, and the rate of air exchange between the inside and outside of the house.

How did ATSDR evaluate air quality in Newtown?

ATSDR evaluated air quality in Newtown using three sets of information. These included air pollutant release data, ambient air models, and measured air contaminant and particulate concentrations. This information is discussed in more detail in following sections.

  1. Air Pollutant Release Data

Government agencies have a number of ways to monitor emissions from industrial facilities. ATSDR utilizes databases and permit files that record air pollutant release data. Air pollutant release data are information about environmental pollutants that are released into the air from manmade and natural indoor and outdoor sources. Each database contains emissions or compliance data for facilities regulated by the EPA or by the state of Georgia.

ATSDR obtained air pollutant release data from the following sources:

  • The EPA Aerometric Retrieval System Facility Subsystem (AIRS/AFS)
  • The EPA Toxic Release Inventory (TRI) database
  • Air permit and compliance files from Georgia Department of Natural Resources (Ga DNR), Division of Air Quality

These data sources are explained on pages 8 through 10.

  1. Ambient Air Dispersion Models

Air dispersion models are mathematical equations that predict (simulate or model) the movement of contaminants. The data generated determine how chemicals are spread through air. Data needed for these air dispersion models include weather (meteorological) data and the amount of pollutants released to the air over time.

For this evaluation, ATSDR reviewed results from two existing EPA models. ATSDR also generated model results based on the information collected from the Air Pollutant Release data described above. The purpose of these models was to recreate past air concentrations in the Newtown community from air pollutants emitted from nearby industries, and determine a range of contaminant levels for residential exposure. Using the meteorological data, emissions data (air pollutant release data), and the contaminant concentrations generated by the ATSDR and EPA models, ATSDR created a plausible and realistic exposure scenario for Newtown residents.

The three models used in this evaluation are:

  • The Agency for Toxic Substances and Disease Registry (ATSDR) Air Dispersion Model
  • The EPA Cumulative Exposure Project (CEP)
  • The EPA National Air Toxic Assessment (NATA)
  1. Measured Ambient Air Concentrations

ATSDR obtained air data collected by the Georgia Department of Natural Resources (Ga DNR). These data include ambient air samples collected at the Fair Street School monitoring station for priority pollutants, as well as particulate concentrations. ATSDR used the contaminant concentrations to measure the accuracy of modeled contaminant predictions, as well as to assess air quality conditions in the community. ATSDR evaluated the air data in detail in the previous public health assessment released in March 2001. However, particulate data have become available since the initial release of that document and are evaluated here.

The Fair Street School monitor is 0.20 miles from Newtown and is geographically elevated from Newtown. ATSDR evaluated the similarity of modeled and monitored concentrations at the school. The air models also allowed ATSDR to compare measured and modeled concentrations at the monitor with modeled concentrations in the community. These comparisons, along with meteorological data, helped ATSDR determine the optimal location for a monitoring station within the community.

Addressing Previous Recommendations and ATSDR Comparison Values

ATSDR made recommendations to further evaluate air in the previous public health assessment for this site (released in March 2001). These recommendations included further evaluation of particulate concentrations in ambient air; potential past exposures to industrial emissions; and whether the current ambient air monitor is at an optimal location for measuring community contaminant concentrations. These recommendations were addressed using the following methodologies:

  • Evaluate particulates in air emissions. ATSDR evaluated particulates in air emissions by reviewing the ambient air monitoring data collected by the Georgia Department of Environmental Protection from February 1999 to March 2000.

  • Evaluate past exposures using models to recreate estimates of past contaminant concentrations. Past air contaminant concentrations were estimated three ways: (1) ATSDR conducted air dispersion modeling of past air emissions; (2) ATSDR obtained and analyzed EPA's 1990 nationwide air modeling of toxic air pollutants; and (3) ATSDR obtained and analyzed EPA's 1996 nationwide air modeling of toxic air pollutants. The nationwide air modeling was specific enough to apply at the county and census tract level.

  • Determine if the current location of the air monitor is in a sufficient location to measure contaminant levels of residential air in Newtown. ATSDR evaluated the air monitor in relation to the air emission sources. The optimal location of the air monitoring station was determined through the use of the ATSDR and EPA air models and meteorological data.

The object of the first two recommendations was to obtain past air concentrations. These air concentrations were then screened with ATSDR comparison values (CVs). The purpose of the third recommendation was to determine whether the current air monitor location is sufficient to estimate contaminant concentrations and resulting exposures to Newtown residents.

CVs are concentrations of chemicals that are considered safe levels of exposure, even for sensitive populations such as children and the elderly. ATSDR selects those contaminants which exceed CVs for further evaluation. While concentrations at or below a particular CV might be considered safe, it does not necessarily follow that any concentration that exceeds a CV would be expected to result in adverse health effects in the community. CVs typically contain built-in safety factors that make them 10-1000 times lower than levels that have been observed to cause adverse health effects in animals or humans. In addition, ATSDR also screened modeled air concentrations using the standard risk assessment methodologies of cancer risk and hazard indexes. Cancer risks and hazard indexes are explained in more detail in Section 3.

Discussion Section 2- Air Pollutant Release Data

As discussed previously, air pollutant release data are information about environmental pollutants that are released into the air from manmade and natural indoor and outdoor sources. In this section, ATSDR evaluates the manmade air releases from industrial and commercial operations in the Newtown area. Air pollutant releases from mobile sources, home activities, and other activities are evaluated in Section 3. Indoor air pollution is not evaluated in this report.

The Air Pollutant Release Databases used for this evaluation include:

  • The EPA Aerometric Retrieval System Facility Subsystem (AIRS/AFS)
  • The EPA Toxic Release Inventory (TRI) database
  • Air permit and compliance files from Ga DNR, Division of Air Quality

The purpose and usefulness of these databases are explained in detail in this section. ATSDR used these databases to identify facilities that are major emitters in southern Gainesville, GA. These facilities were included in the ATSDR air dispersion modeling.

The Aerometric Retrieval System and Facility Subsystem (AIRS/AFS)

What is a point source? -- A point source is a stationary location or fixed facility such as an industry or municipality that discharges pollutants into air or surface water through pipes, ditches, lagoons, wells, or stacks, or a single identifiable source such as a ship or a mine.The AIRS/AFS database contains emissions and compliance data on air pollution point sources regulated by the EPA, the state, and local regulatory agencies under the Clean Air Act. AIRS/AFS contains data on industrial facilities, power plants, and other similar sources. In general, emissions data are provided for criteria air pollutants (sulfur oxides, nitrogen oxides, particulate matter, carbon monoxide, volatile organic compounds, and lead) and select hazardous air pollutants [13]. More information about the AIRS/AFS database is provided in Appendix C.

ATSDR found 106 facilities in the AIRS/AFS database for Hall County [13]. Of these 106 facilities, ten are considered to be significant sources (Appendix C, Table 1). Because they are significant sources of air pollutant emissions, the AIRS/AFS database contains specific information about these pollutants and where they are released.

Of these ten facilities, only four were located within four miles of the Newtown Community. The adequacy of the four mile limit is illustrated in Appendix D and discussed in Section 3. These facilities are listed in the table below.

Table 3. Major Sources for Air Pollutants Within 4 Miles of Newtown Community

Facility Address City Industry Type Stacks Estimated emissions of volatile organic compounds (tons/year)
Benjamin Blatt 2100 Atlanta Hwy Gainesville Weaving Mills, Cotton 4 56
Cargill 949 Ridge Road Gainesville Soybean Oil Mills 2 0
Milliken & Co New Holland 1750 Jesse Jewell Parkway Gainesville Weaving Mills, Cotton 1 3
Moreno Press 3915 Old Mundy Mill Road Oakwood Commercial Printing 2 197

The Toxic Release Inventory database (TRI)

What are fugitive emissions? -- Fugitive emissions are air emissions from locations other than stacks, vents, chimneys, or other fixed locations designed for releasing emissions. Examples include pump and valve leaks at oil refineries, fumes escaping out a window at a paint factory, or fumes evaporating from the gas tank during refilling.The TRI is a database of information collected by EPA from selected manufacturing and waste management facilities. Certain types of businesses are required to report the use and release of about 650 toxic chemicals to EPA. The TRI includes air emissions data from point sources and fugitive emissions [5]. More information about the TRI database is provided in Appendix C.

For Hall County, ATSDR located 39 facilities in the TRI database [5]. Of the 39 facilities, ATSDR investigated the emissions of 24 facilities because they were within 4 miles of the Newtown Community. ATSDR reduced the set further and only focused on those facilities releasing more than 500 pounds per year of a chemical. This set resulted in 20 facilities, some of which are in close proximity to the community. Table 2 in Appendix C lists these facilities.

The air permit and compliance files from the Georgia Department of Natural Resources

ATSDR visited the office of the Ga DNR, in the Division of Air Quality to search the files for air permits and compliance information for facilities reporting to the TRI. These files contain air permit applications, air permits, compliance reports, and letters concerning air releases from facilities regulated under the Clean Air Act by the State of Georgia. ATSDR reviewed the files of selected companies in Hall County identified by the AIRS/AFS and TRI databases to verify information or to obtain additional data. Files for the following facilities were reviewed: Cargill; Conagra; Georgia Chair; Purina; Benjamin Blatt/Chicopee/Johnson and Johnson Manufacturing; and the New Holland Milliken plant.

Section 3- Air Models Used in the ATSDR Evaluation of Air Quality in Newtown

ATSDR implemented a model based on data collected from the air pollutant release data (Section 2). This model, along with the Cumulative Exposure Project (CEP) and the National Air Toxic Assessment (NATA) EPA models mentioned in Section 1 were used to obtain an estimate of past air concentrations in the Newtown community from air pollutants emitted into the air from nearby industry, and to determine a range of contaminant levels residents could be exposed. Each of the three models is explained here in detail.

  1. ATSDR's Air Dispersion Model

What is a stack? -- A stack is a source where facility emissions are released into air. A stack is similar to a chimney at a home. Residents have probably seen stacks rising above a plant with smoke (usually steam that appears white) being pumped out. --- Why is stack information important? -- Stack information is important in determining how a contaminant is dispersed in air, such as the stack height and width. The higher the stack, the further out emissions are dispersed. Conversely, the shorter the stack, the more likely the contamination is falling closer to the plant. Also, emission rates from stacks (how much per time, at what speed, and under how much pressure) determine how much is released to the air and how the chemicals disperse in the air.ATSDR uses the air pollutant release data from the sources discussed in the previous section in an air dispersion model to recreate historic air concentrations of the Newtown community. ATSDR modeled the air pollutant releases of 25 chemicals from the 20 facilities identified in the previous section using the emission rates listed in Table 1 (list of facilities and chemicals). The stack data for these facilities are listed in Table 2, Appendix D. The chemicals emitted, their emission rates, and stack parameters were obtained from data collected in the three data sources described in the previous section. For a few of the facilities, the same information differed between sources. In addition, the emission rates and the chemicals emitted varied from year to year. ATSDR simplified these variations by doing the following:

  • ATSDR used stack information from the GA EPD files when available because they were the most accurate. If stack information was not available, ATSDR selected the parameters from the other sources that would have produced the highest ground-level air concentrations. If the air emissions were identified as fugitive emissions, by definition, stack parameters were not available but assumed to be emitted from the roof of a 2-story building (approximately 20 feet) at a very slow speed.

  • Reported chemicals and their emission rates were obtained from the AIRS/AFS database, the TRI database, and permit and compliance records. The reported chemicals and their emissions rates often varied between data sources for the same year and between years. In these cases, ATSDR selected the highest emission rates and selected each chemical identified regardless of the year. In some cases, the emission rates from one facility for one chemical in one year (e.g., toluene in 1988) were combined with a second chemical in a different year (e.g., methanol in 1986). This combination produced a maximum worst case emission scenario which would produce a worst case air concentration people could have been exposed to. As a result, chemicals with predicted low concentrations below CVs could be removed from further evaluation with high confidence that they do not pose a health threat to residents. Chemicals with concentrations above comparison values were evaluated further.

Hazard Quotient (HQ): A comparison of a persons daily chemical exposure to the Minimum Risk Level (MRL) or Reference Air Concentrations (RfC). The value is used as an assessment of the associated cancer and noncancer toxic effects of chemicals, e.g., kidney or liver dysfunction. It is independent of a cancer risk, which is calculated only for those chemicals identified as carcinogens. A hazard index or quotient of 1 or less is generally considered safe. A ratio greater than 1 suggests further evaluation. The HQ is used as a screening value and overestimates the potential hazard. --- Hazard Index (HI): A summation of the Hazard Quotients for all chemicals being evaluated to determine the cumulative effects of different chemicals. A Hazard Index of 1.0 or less means that no adverse human health effects (noncancer) are expected to occur. A ratio greater than 1 suggests further evaluation. The HI is used as a screening value and overestimates the potential hazard.This information together with facility locations, and meteorological information (wind speed, wind direction, etc.) were entered into a modeling program. A hypothetical exposure scenario reflected the maximum air contaminant concentrations and maximum impact areas. Examples of the modeled air concentrations for arsenic, manganese, and hexane are shown in Figures 1, 2, and 3 in Appendix D. Arsenic and manganese were selected because the predicted ambient concentrations contributed the most health risk. Hexane is included at the request of residents. The air concentrations from each facility varies as a result of the facility's location, chemicals emitted, emission rates, and stack parameters.

ATSDR estimated an overall hypothetical health risk using standard risk assessment methods to investigate the impact of all contaminants in ambient air. The air concentrations for each chemical from each facility was converted to a hypothetical cancer risk and/or a non-cancer hazard quotient.The cancer risks were summed to create a total hypothetical cancer risk from all companies and for all chemicals. Similarly, the non-cancer hazard quotients were summed to create an overall hazard index. Hypothetical cancer risks and non-cancer hazards of the modeled concentrations are illustrated in Figures 4 and 5, Appendix D. These hypothetical values were used as a screening tool to focus the investigation on contaminants that were present in sufficient quantity and toxicity to warrant further investigation. These contaminants were identified as "contaminants of concern" (COCs).

As seen in Appendix D, facilities closer than 4-miles seem to have the largest influence on historical air concentrations.

Meteorological Data

Meteorological data consists of two main components; surface data and upper air data. For the preceding discussion and figures, ATSDR used the surface data from the Atlanta Hartsfield Airport and upper air data from the Athens Ben Epps Airport. The Atlanta Hartsfield Airport data were used based on recommendations from the state. Athens Airport was used for upper air data because it was the only data available in the state that matched with the years of the surface data.

After the modeling was completed, surface meteorological data from the Gainesville Lee Gilmer Airport became available. ATSDR evaluated the effects of using the Gainesville data on the results by comparing wind roses and modeling the emissions of hexane from Cargill and manganese from Purina. The wind roses show a slightly different pattern (Figure 6, Appendix D) with a greater wind from the west in the Gainesville surface meteorological data (See Appendix D for issues regarding the meteorological data obtained from the Gainesville airport. This different pattern has the effect of stretching out the dispersion of emissions from Cargill and Purina in a eastern direction with a much smaller stretch in the western direction). Figures 1-3, Appendix D overlays the predicted concentrations using both sets of meteorological data and show this stretching effect. The predicted concentrations of manganese from Purina using either meteorological data (Atlanta or Gainesville) was about the same because of the close proximity of the plant to the community. In the case of hexane from Cargill, the predicted air concentrations using the Atlanta meteorological data were greater because the Atlanta meteorological data creates a greater dispersion to the north. As a result, all the emissions, except for those from Purina (Purina is located to the east of Newtown) are expected to have predicted higher concentrations in the Newtown community when using the Atlanta meteorological data. Because the Atlanta meteorological data produces greater predicted concentrations in the Newtown community, ATSDR used the original modeling results in the rest of this document to make a conservative health evaluation. For comparison purposes, Figure 6, Appendix D shows wind direction and speed for both the Atlanta Hartsfield Airport and the Gainesville Lee Gilmer Airport.

  1. EPA's Cumulative Exposure Project

EPA conducted the Cumulative Exposure Project (CEP) for the continental United States to examine the toxic contamination to which Americans are exposed cumulatively through air, food, and drinking water. The study estimated exposure levels for different communities nationwide. The air component was the only one completed. The air toxic component of the CEP is an assessment of estimated 1990 outdoor concentrations of 147 air pollutants. Concentrations were reported as an average for each census tract. The values for the Newtown Community census tract are presented in Table 1, Appendix E. The air toxic component is presented here as another estimate of air concentrations of these contaminants people could have been exposed to in Newtown. While ATSDR's model included site-specific facility emissions only, the CEP included mobile emissions and other facility emissions (see Appendix E).

As was done for the ATSDR air dispersion modeling, ATSDR calculated an overall hypothetical health risk using the hazard index and cancer risk for each of 147 air contaminants. The results for Hall County are shown in Figures 1 and 2, Appendix E.

Five contaminants presented the greatest hypothetical health risk: benzene, 1,3-butadiene, carbon tetrachloride, chloroform, and formaldehyde. The predominant source of these contaminants is on-road vehicles. The second highest source contributor was waste disposal, treatment, and recovery, which includes residential and commercial open burning. The emissions, displayed by emissions category is presented in Figure 3, Appendix E.

The five contaminants posing the greatest hypothetical risk to residents were not identified in the ATSDR air dispersion model, because they are released from mobile sources. ATSDR did not model mobile emissions because we wanted to determine the impact of facilities on the community. We evaluated our results and those of the EPA models to compare an exposure scenario with and without mobile emissions. This allowed us to evaluate the impact of mobile emissions on residential air, as well as the impact of facility emissions on residential air.

ATSDR compared the hypothetical cancer risk and noncancer hazard index generated from the CEP model to results from all census tracts in Georgia. The results are shown in Appendix E, Figures 4 for carcinogens (cancer-causing agents) and Appendix E, Figure 5 for noncarcinogens. It is obvious in these two maps that people living in larger cities and near industrial areas have substantially higher hypothetical risk of cancer and other types of illnesses. Interestingly, much of the risk reported in the CEP modeling effort is from on-road mobile emissions (cars, trucks, buses, etc.). For cancer in Georgia, the estimated cancer risk ranged from 0.00003 to 0.0012. The average is 0.0001 and the median is 0.0007. From this, we have determined that the Gainesville average of 0.00012 is about average for the state.

The non-cancer hazard index in Georgia ranges from 1.38 to 10.4. The average is 8.9 and the median is 7.4. Figures 6 and 7, Appendix E show a comparison of Gainesville with five other cities for cancer and non-cancer risk. From this, we can see that Gainesville value of 8.2 is about average for the state. These data suggest that the residents in the Gainesville area do not experience a significantly higher theoretical risk of disease from air emissions than other similar cities in Georgia, or in Georgia as a whole. Although the data do not suggest elevated risk above other industrial areas in the state, it is possible that the types of contaminants present in Gainesville (as in many cities) can cause non-life threatening respiratory illness and discomfort. More specific information about this model and the results is supplied in Appendix E.

  1. EPA's National Air Toxic Assessment

ATSDR also evaluated the calculated estimates of historical air concentrations with EPA's National-Scale Air Toxic Assessment (NATA). The EPA National-Scale Air Toxic Assessment (NATA) is a followup to the EPA Cumulative Exposure Project with many changes including a more extensive emission inventory and modeling based on 1996 emissions. The NATA model is limited and more general in that 33 compounds were modeled instead of 147 compounds in the CEP and the data are available only at the county level instead of the tract level. Detailed information is available from EPA at http://www.epa.gov/ttn/atw/ .

In addition to ATSDR's air dispersion modeling, ATSDR calculated an overall hypothetical health risk using the hazard index and cancer risk for each of the 33 air contaminants.

The cancer risk and non-cancer hazard index for 1996 is presented in Figures 1 and 2 (Appendix F) respectively. These figures illustrate the total hypothetical risk and hazard index as well as the risk and hazard indexes from each source. The total cancer risk is 0.000056 and the noncancer hazard index is 5. These measurements are about the same as the CEP model discussed above even though the number of modeled compounds is less than the CEP model.

The above model revealed very similar results to the CEP model. The model suggests that four chemicals contribute 85% of hypothetical health risk: 1,3 butadiene, carbon tetrachloride, formaldehyde, and benzene (in order from largest to smallest contributor). The predominant source of these contaminants with the exception of carbon tetrachloride is mobile sources, on and off-road. The main source of carbon tetrachloride is background emissions. Background concentrations which are are represented by inclusion of concentration values measured at "clean air locations" remote from the impact of local manmade sources. Background concentrations only exist for air pollutants with very low reactivity (i.e. how quickly it is removed through chemical transformation) in the environment. For the noncancer health outcomes, the predominant hazard is from acrolein which is formed from the breakdown of 1,3-butadiene which is emitted from on-road vehicles. Waste disposal, treatment, and recovery operations and non-road mobile emissions are the second and third major sources of acrolein. Waste disposal, treatment, and recovery operations include waste incineration (municipal residential, or commercial/institutional), open burning on-site or at dumps (residential and commercial), wastewater treatment, and emissions from landfills. No waste incineration plants are currently located in Hall County.

Section 4- Measured Results and Their Comparison to Models

Priority Pollutants

ATSDR evaluated contaminant levels measured by the Fair Street School monitoring station which is described in the previous Newtown public health assessment. We concluded that "...although many metals and volatile organic compounds (VOCs) were detected in these monitoring efforts, the data revealed that these contaminants were detected far below levels at which adverse health effects have been observed in humans... Furthermore, most were detected infrequently [1]".Because levels rarely exceeded CVs and were not found with a high level of frequency, ambient air contaminant levels detected by the Fair Street School monitor are not a threat to human health. However, the location of the Fair Street School monitor may not be representative of Newtown ambient air conditions, and an investigation of this sampling location was warranted.

ATSDR provided residents with self-collection canisters to monitor ambient air in addition to the sampling data from the monitoring station. Benzene was the only contaminant that exceeded ATSDR's health based guidelines, but was far below any concentration which has been observed to cause health effects. However, ATSDR did identify elevations of other contaminants outside the boundaries of the community. For this sampling effort, ATSDR concluded that "...data analyzed for the ATSDR exposure investigation do not indicate a health hazard in residential ambient air. However, the isolated elevations of VOCs detected in air may warrant the relocation of the state air monitor closer to the community so that these contaminants may be more closely monitored...[1]" In other words, the monitor may not detect the higher concentrations ATSDR measured nearer to the facilities, given its location. Appendix I, Tables 1 and 2 illustrate these results.

Particulate Matter

ATSDR evaluated particulates in air emissions by evaluating the ambient air monitoring data collected by the Georgia Department of Environmental Protection from February 1999 to March 2000. Air monitoring technology has the capability of monitoring air particles in a range of sizes, measured in micrometers. PM10 refers to particulates that are 10 micrometers in diameter or less, and PM2.5 refers to dust particulates that are 2.5 micrometers in diameter or less. Total suspended particulates (TSP) refers to the particulate concentration of particulates of all sizes. The TSP procedure captures measurable particulates as small as 0.1 micrometers (40 CFR50- Appendix B). EPA has established regulatory guidelines of particulate concentrations that are safe to breathe in ambient air. Until 1987, EPA had specific regulations for TSP of 150 µg/m3 (micrograms per cubic meter) for 24-hour averages and 75 µg/m3 for annual averages. In 1987, EPA developed more specific guidelines based on PM10. The current EPA PM10 acceptable levels are 150 µg/m3 24-hour average and 50 µg/m3 annual average.

With recent studies linking inhalation of fine particles to adverse health effects in children and other sensitive populations, EPA proposed regulating ambient air concentrations of PM2.5 in 1997. These health-based regulations require annual average concentrations of PM2.5 to be less than 15 ug/m3 and 24-hour average concentrations to be less than 65 ug/m3. Although many different sources emit PM2.5, these particulates are primarily emitted by combustion sources (e.g., motor vehicles, power generation, boilers and industrial furnaces, residential heating). Fine particles are also formed in the air from other pollutants. Although EPA's promulgation of the PM2.5 standard is still under legal review, ATSDR uses the proposed standard, and the scientific evidence that supports this standard to evaluate inhalation exposures to PM2.5 [14] because the scientific data indicate that these smaller particles--less than 2.5 microns in diameter--are more respirable and largely responsible for the health effects of greatest concern [10].

In the Newtown community, PM2.5 was sampled continuously for 14 months (February 1999 to March 2000) at the Fair Street School location, and 24-hour averages were taken every day during that time. The measured PM2.5 results for this time period were below the EPA proposed standard of 65 µg/m3 (24-hour average). However, the annual average for 1999 was 18.4 µg/m3 and for 2000 it was 16 µg/m3, both of which exceed the EPA recommended annual concentration of 15 µg/m3. See Table 3, Appendix I for particulate sampling data. It appears that the summer months (June-August) had the highest concentrations of PM 2.5 dust.

ATSDR discusses the health issues relating to these concentrations in the Health Implications Section (Section 6).

Comparison of Modeled Results with Measured Results

ATSDR compared the air modeling results with air concentrations measured by Ga DNR to evaluate the performance of the models and the representativeness of the model results. However, there were several limitations of this comparison, which include:

  1. The air monitoring data are from 1997 and the ATSDR air modeled results are from a worst case condition from emissions data collected from 1983 to 1998; The CEP model results are from emissions in 1990; and the NATA results are from emissions in 1996.

  2. Emissions used in the ATSDR air modeling were based on worst case maximums when data existed. On the other hand, data not reported to EPA or Ga DNR could not be modeled. The measured air concentrations represent an average concentration over a given sampling period. The modeled concentrations are annual averages.

  3. The air monitor was located on the top of a school at 5 meters above the ground (16 feet above ground on the school roof) while the air modeled calculated concentrations at 1.5 meters above the ground (near the breathing zone for an adult). The CEP and NATA results are at levels modeled at the ground surface.

  4. The ambient monitor sampled air that included all sources. The ATSDR air modeling only included point source emissions. As a result, mobile emissions were not included in the ATSDR air model. The CEP and NATA results included all known sources. The CEP model included many more chemicals than the monitoring station at the Fair Street School. The NATA model included only 33 chemicals some of which were not sampled.

Mobile emissions are an important source of air contamination in urban settings. ATSDR did not model them in its analysis because we were interested in estimating the level of risk contributed by facility emissions only. Therefore, we used EPA's Cumulative Exposure Project and the EPA's National Air Toxic Assessment which did include mobile emissions. The comparison of these models allowed the comparison of emissions from facilities only from those contributed by other sources. Thus, the exposure scenario for facility emissions as compared to all source emissions emerges. See Table 3, Appendix D for a comparison table of measured and ATSDR modeled concentrations. As illustrated, formaldehyde and acrolein are two important chemicals that are not reported to be emitted by facilities and are not sampled at the Fair Street monitor. 1,3-Butadiene is sampled and analyzed for but the results for 1997 were not reported because the results did not pass quality assurance/quality control standards.

Table 4. Comparison of results-ambient concentrations versus modeled concentrations

Modeled levels of ambient air contaminant sources compared to measured concentrations (annual average-µg/m3)

Contaminant Measured air concentrations 1997
(mean)
ATSDR modeled concentrations
(at the air monitor)
ATSDR modeled concentrations
(maximum in the Newtown Community)
EPA Cumulative Exposure Project concentrations
(average over census tract)
EPA National Air Toxic Assessment concentrations
(average of county)
hexane 2.06 4.05 14.72 (13.42)* 1.43 NA
manganese 0.022 .0058 0.075 (0.08) .0024 .0008
carbon tetrachloride <2.19 NA NA 1.015 0.88
benzene 1.1 NA NA 2.82 1.14
formaldehyde NA NA NA 1.01 0.854
1,3-butadiene NA NA NA 0.1392 0.05
acrolein NA NA NA 0.1346 0.0867

*Contaminants in parentheses are those calculated using Gainesville airport meteorology
ug/m3: micrograms per cubic meter of air

Discussion Section 5- Location of the Air Monitor and Monitoring Parameters

The location of the air monitor is important for determining the air contaminant concentrations to which Newtown residents would have been exposed. Based on the site specific air dispersion modeling, ATSDR concludes that a community exposure monitor would have been better located in an area ranging from the east to the southeast in or near the perimeter of the Newtown community to accurately reflect the exposures of residents to facility emissions. This conclusion is explained in the remainder of this section.

The existing location of the monitor is based on the Newtown Statement of Work (SOW) [15]. In the SOW, the purpose of the air monitor is to understand the effects of various sources both for the anthropogenic and biogenic compounds on the ambient air quality of Newtown and for the health of the community. However, in November 2001, GaDNR reported to ATSDR that the purpose of the current air monitor has changed. It is no longer a community exposure monitor, but instead is now being used as a general air toxics monitor.

The current air monitor is located on the roof of the Fair Street Elementary School located approximately 0.2 miles north of the Newtown community. Additionally, the school is elevated approximately 20 to 60 feet above the Newtown community. The SOW explains that the selection of the sampling sites was based on meteorological history, availability, access, security, power supply, and safety. The meteorological history was obtained by the State through the use of a portable meteorological station collecting wind direction, wind speed, ambient temperature, relative humidity, solar radiation, and barometric pressure from April 1995 through January 1996. The station was located on the roof of the Fair Street Elementary School. This station reported that undetectable winds (called 'calms') were the predominate wind ranging from 22 to 40% of the time. The second most predominant wind direction was from the west to northwest. The third most predominant wind direction was from the east. Based on the secondary and tertiary wind directions alone and the air modeling explained below, the current air monitor is not in an ideal location since the industry is located to the east, south and southeast of the Newtown community. These wind directions are illustrated with the map on page 19.

In 1997, the Federal Aviation Administration (FAA) in conjunction with the National Oceanographic and Atmospheric Administration (NOAA) started operating an automated surface observing meteorological system (ASOS) at the Gainesville Lee Gilmer Memorial Airport. The airport is approximately two miles southwest of Newtown. Wind rose data for years 1997 through 2000 are presented in Figure 6, Appendix D. These data concur with the data collected by the portable monitor in 1995 except that calms range from 10.6 to 11 percent instead of 22 to 40%. Seven of the 16 aggregated wind directions (plus calms) account for 71% of the time as shown below:

West 13.5%
Calms 11.3%
West Northwest 11.2%
East 9.8%
East Northeast 9.6%
West Southwest 8.0%
Northwest 7.7%
Total 71.1%

Monitor Location, Wind Rose and Location of Significant Point Sources
Monitor Location, Wind Rose and Location of Significant Point Sources

Based on this data, the air monitor is located in a predominantly upwind direction, 24.7% of the time. The second most frequent winds are from the East and East Northeast. These winds would pick up emissions from Purina with the biggest impact to west of Purina while the monitor is located to the northwest.

According to EPA [16], dispersion modeling is a good tool to identify candidate air monitor sites because the modeling identifies areas of maximum concentrations and most frequently impacted areas. ATSDR conducted air dispersion modeling to determine the impact of local facilities on Newtown ambient air. Figures 2 and 3, Appendix D presents the modeled air concentrations from Purina and Cargill emissions, respectively. As shown, concentrations in the community from Purina and Cargill could be 5 to 10 times higher than those measured at the current air monitor location. The maximum impacted areas from Cargill and Purina would be in areas ranging from the east to southeast.

The impact of emissions from cars is another factor in the location of the air monitor. In Section 6, emissions from mobile sources such as cars is identified as the predominant source of air toxic in the area. ATSDR's monitoring results were intended to represent the air quality of the Newtown community.

As in any urban area, heavy traffic exists in the Gainesville area. The roads with data on traffic volume surrounding the Newtown community include Myrtle Street to the north with 11,000 vehicles per day, US 129 or Athens Highway to the southwest with 35,000 vehicles per day, Athens Street to the southwest with 8,500 vehicles per day, and Interstate 985 to the south/southwest with about 30,000 vehicles per day [17]. The monitor in relation to these roads ranges from north to west. If the wind was blowing from the predominant wind direction (west, northwest), the air monitor would be upwind. However, with the distribution of the roads around Newtown, the most significant factor is the distance from the roads to the monitor. Because Newtown is closer to these roads than the current air monitor, the community is expected to have higher air concentrations of pollutants from the traffic than what is monitored.

Availability, access, security, power supply, and safety are also factors that need to be considered in siting the air monitor. While the school is excellent for these factors, the meteorology and location of sources are more important. Hence, the monitor was not in an optimal location for measuring exposures in the Newtown Community. Locations better suited for monitoring the Newtown Community, based solely on the meteorology and location of point sources, is illustrated in the Figure on Page 19.

According to GaEPD, the purpose of the air monitor, has changed from "understanding the effects of various sources both for the anthropogenic and biogenic compounds on the ambient air quality of Newtown and for the health of the community" [15] to monitoring the air in the general Gainesville area. Either way, the location of the monitor and the spatial distribution of air pollution must be considered when the results of the air monitor are applied to the Newtown Community.

The compounds monitored for by the GaEPD includes those listed in Table 3 (page D-7) and Table 1 (page E-4). These compounds were collected using EPA Methods TO13 and TO14 and a PUF method. These methods do not sample for two important chemicals of concern, acrolein and formaldehyde, that have been identified in the CEP air modeling. As a result, ATSDR would like to see additional chemicals sampled for. However, there are limitations in the available sampling methodology that makes analyzing for some compounds very difficult and/or very expensive.

Of the states reporting to EPA in 1997, eight measured urban air for acrolein and 16 for formaldehyde. For acrolein, several states tried to use method TO-11A but had difficulty getting results above the minimum detection levels, had poor recovery, or the samples were not stable [18]. However, method TO15 [19] may be a potential method to use.

Georgia monitors for formaldehyde at two air monitoring stations in DeKalb County as part of the photochemical assessment monitoring program (PAMS) in Georgia using Method TO-11A [20]. Monitoring for formaldehyde in areas of non-attainment for national ambient air quality standards is required by U.S. EPA. Georgia has been monitoring formaldehyde at one DeKalb County location since 1996 and a second station in DeKalb County since 1999. Mean concentrations from 1996 through 2000 have ranged from 1.1 to 9.9 µg/m3 (maximums have ranged from 6.3 to 39 µg/m3).

Although methods TO-11A and TO15 describe the analysis of formaldehyde and acrolein, respectively, the methods are reported to be trouble prone [21-23]. As a result, EPA may not includes these two compounds in the proposed national air toxics monitoring program [18,23]. EPA is also considering dropping formaldehyde from the PAMs requirements [22].

Since there are problems with monitoring acrolein and formaldehyde in urban air, ATSDR requests that Georgia Environmental Protection Division periodically review (at least annually) the available sampling and analytical methodology for these two compounds. Once the methodology meets the quality control and assurance requirements, ATSDR requests that air samples in Gainesville be collected and analyzed periodically for acrolein and formaldehyde.

Discussion Section 6- Health Implications Section- Contaminants of potential adverse health effects;
Individual chemical concentrations and their implications on health in this community

Contaminants of concern were identified by those contaminants contributing 10% or greater hypothetical cancer risk or noncancer health effects based on air monitoring, ATSDR's air modeling, or EPA's Cumalative Exposure Project (CEP) and National Air Toxic Assessment (NATA) models. In addition, hexane is included because of the community's concern. All health risk calculations were based on the highest level measured or monitored among EPA studies (the CEP and NATA), ATSDR's modeling, or Georgia EPD's air monitoring to form a worst-case risk estimate. These calculations assume that residents are only exposed to each chemical separately. That is not the case in Newtown. A section on the air quality in general and how it may effect Newtown residents is presented following the discussion of individual contaminants.

1,3-Butadiene

ATSDR does not expect adverse health effects from current levels of exposure to 1,3-butadiene. Exposure to 1,3 butadiene would most likely not cause noticeable increases in cancer or non-cancer health effects.

Chemical Properties
1,3-Butadiene is a colorless gas with a mild gasoline-like odor. 1,3-Butadiene is almost always found at low levels in urban air samples. In sunny weather, half of 1,3-butadiene is eliminated from air in about 2 hours. Because it is found in the exhaust of cars and trucks, it is always present at very low levels in the air around cities and towns. In high-traffic areas, the release of 1,3-butadiene to the atmosphere occurs continually. The average amount of 1,3-butadiene in the air is 0.3 parts of 1,3- butadiene per billion parts of air (ppb) in cities and suburban areas. These levels are not expected to cause health problems. The amount of 1,3- butadiene in the air may be much higher near polluted cities or near oil refineries, chemical manufacturing plants, and plastic and rubber factories where this chemical is made or used [24].

Very large amounts of 1,3-butadiene are produced every year from petroleum. 1,3-Butadiene is used to make man-made rubber, which is then used mostly for car and truck tires. It is also used to make other kinds of rubber and plastics. 1,3-Butadiene is also found in small amounts in gasoline. Some plastics or man-made rubbers may have very small amounts of 1,3-butadiene trapped in them. These levels are not expected to be high enough to cause health problems. Small amounts are found in the exhaust of automobiles and trucks at approximately 10 ppb air and in gasoline vapors at 4 ppb. 1,3-Butadiene is also found in cigarette smoke, and it may also be found in the smoke of wood fires [25,26]. The average amount of 1,3- butadiene in sidestream cigarette smoke is 205-361 µg/cigarette [27], with an average airborne yield of 400 µg/cigarette [24,28].

Health implications
Although 1,3-butadiene can cause serious health problems, the levels modeled and reported here do not suggest a threat to residents from exposure. The highest level modeled was 0.14 µg/m3 (0.062 ppb).No adverse health effects are known to be caused by 1,3-butadiene at concentrations below 6,000 ppb in air [24]. The ambient air monitoring conducted by the Ga DEP did not include the analysis of 1,3-butadiene.

Carbon tetrachloride

The levels of carbon tetrachloride in Newtown are not expected to result in cancer or other illnesses in Newtown.

Chemical properties
Carbon tetrachloride is a clear liquid with a sweet odor that evaporates very easily. It does not occur naturally but has been produced in large quantities to make refrigeration fluid and propellants for aerosol cans. Since many refrigerants and aerosol propellants have been found to affect the earth's ozone layer, the production of these chemicals is being phased out. In the past, carbon tetrachloride was widely used as a cleaning fluid (in industry and dry cleaning establishments), as a degreasing agent, and in households as a spot remover for clothing, furniture, and carpeting. Carbon tetrachloride was also used in fire extinguishers and as a fumigant to kill insects in grain. Most of these uses were discontinued in the mid-1960s. Until recently, carbon tetrachloride was used as a pesticide, but it was banned in 1986 [29].

Typical ambient air concentrations of carbon tetrachloride in rural areas are about 1 mg/m3 , with somewhat higher values in urban areas and near industrial sources [30-32]. A minimum risk level (MRL) of 50 ppb has been derived for intermediate inhalation exposure to carbon tetrachloride [29]. MRLs are an estimate of daily human exposure to a dose of a contaminant that is likely to be without appreciable risk of adverse noncancerous effects over a specified duration of exposure.

Health implications
Although carbon tetrachloride can cause serious health problems, the levels modeled and reported here do not suggest a threat to residents from exposure. No adverse health effects in acutely (exposure for 14 days or less) exposed humans has been observed in scientific studies below 50,000 ppb. No human or animal studies exist for chronic exposures (365 days a year or more). However, all established No-Adverse-Effect-Levels (NOAELs) for intermediate exposure in humans or animals are above 10,000 ppb. A NOAEL is a level at which no adverse health effects have been observed in humans or animals in toxicological or epidemiological studies. The observed levels were far below these effect levels, so ATSDR does not expect residents to suffer adverse non-cancer effects from carbon tetrachloride exposure.

Formaldehyde

The levels modeled in this community would not pose a health threat if they were measured to be actual concentrations.

Chemical properties
Formaldehyde is an important industrial chemical used to make other chemicals, building materials, and household products. Formaldehyde is a manmade and naturally occurring substance. Formaldehyde serves many purposes in products. It is used as a part of the glue or adhesive in pressed wood products (particle board, hardwood plywood, and medium density fiberboard (MDF)); preservatives in some paints, coatings, and cosmetics; the coating that provides permanent press quality to fabrics and draperies; the finish used to coat paper products; and certain insulation materials (urea-formaldehyde foam and fiberglass insulation). Formaldehyde can slowly be released from materials made with it. Products that may add formaldehyde to the air include particle board used as flooring underlayment, shelving, furniture and cabinets; MDF in cabinets and furniture; hardwood plywood wall panels, and urea-formaldehyde foam used as insulation [33]. Formaldehyde is present in many different consumer products; even cosmetics have a small amount of formaldehyde in them. Formaldehyde is also released into the air by burning wood, kerosene or natural gas, by automobiles, and by cigarettes.

Formaldehyde is normally present at low levels, usually less than 30 ppb, in both outdoor and indoor air [33]. The outdoor air in rural areas has lower concentrations while urban areas have higher concentrations. Most suburban areas have ambient concentrations ranging between 2 and 6 ppb, and near industry and heavy traffic, residents can be exposed to 10-20 ppb [34]. Generally, indoor residential formaldehyde concentrations are significantly higher than outdoor concentrations. Homes that contain large quantities of particle board or formaldehyde foam insulation (UFFI) have been measured at 20 ppb to 4,000 ppb. However, since the 1980s the use of UFFI has been reduced significantly. Newly constructed homes have levels between 35 ppb and 76 ppb. Older homes tend to have the lowest concentrations, at approximately 50 ppb [34].

Health implications
Formaldehyde was not analyzed in Ga DNR ambient air studies, so ATSDR analyzed the CEP modeled concentrations. The highest level modeled was 1.01 µg/m3 (0.82 ppb). No adverse health effects have been observed in humans below 80 ppb[34].

Benzene

ATSDR does not expect benzene concentrations in Newtown to result in cancer or non-cancer illnesses.

Chemical properties
Benzene, also known as benzol, is a colorless liquid with a sweet odor. Most people can begin to smell benzene in air at 1.5-4.7 parts of benzene per million parts of air (ppm). Benzene found in the environment is from both human activities and natural processes. Today, benzene in the air is mostly from manmade sources. Because of its wide use, benzene ranks in the top 20 in production volume for chemicals produced in the United States. Various chemicals and products are made from benzene including styrene (for Styrofoam® and other plastics), cumene (for various resins), and cyclohexane (for nylon and synthetic fibers). Benzene is also used for the manufacturing of some types of rubbers, lubricants, dyes, detergents, drugs, and pesticides. Natural sources of benzene include volcanoes, forest fires, and crude oil. Benzene is an emissions product of gasoline [11].

Benzene levels in air can increase from burning coal and oil, benzene waste and storage operations, motor vehicle exhaust, evaporation from gasoline service stations, and use of industrial solvents. Since tobacco contains high levels of benzene, tobacco smoke is another source of benzene in air.

Benzene is widely distributed in the environment. The exposure scenario of most concern to the general public is low-level inhalation over long periods. This is because the general population is exposed to benzene mainly through inhalation of contaminated air, particularly in areas of heavy traffic and around gas stations, and through inhalation of tobacco smoke from both active and passive smoking [35-39]. Smoking has been identified as the single most important source of benzene exposure for the estimated 40 million U.S. smokers [40,41]. Smoking accounts for approximately half of the total benzene exposure of the general population [40]. Individuals employed in industries that make or use benzene, or products containing benzene, are probably exposed to the highest concentrations of atmospheric benzene [42-44]. Of the general population, those residing around certain chemical manufacturing sites or living near waste sites containing benzene may be exposed to concentrations of benzene that are higher than background air concentrations. In private homes, benzene levels in the air have been shown to be higher in homes with attached garages, or where the inhabitants smoke inside the house [11,45].

Studies have determined that median outdoor ambient air benzene concentrations in the United States range from 4.8 to 35 ppb, with the overall median being 12.6 ppb. These studies have also indicated that mobile sources were the major source of benzene in the vast majority of samples [46]. In California, motor vehicle exhaust and motor vehicle fuel evaporation accounted for 79.8% of the population exposure to ambient benzene [47].

In EPA's Total Exposure Assessment Methodology (TEAM) study, indoor population-weighted personal exposures to benzene exceeded exposures from outdoor air concentrations. The overall mean personal exposure was about 15 µg/m3 (4.7 ppb), compared to an overall mean outdoor concentration of only 6 µg/m3 (1.9 ppb). The study also reported that smoking significantly increased the dose of benzene in the home. The median level of benzene in 185 homes without smokers was 7 µg/m3 (2.2 ppb), and the median level of benzene in 343 homes with one or more smokers was 10.5 µg/m3 (3.3 ppb) [41]. This finding points to the possible significance of passive smoke as a source of benzene exposure. Indoor air samples taken from a smoke-filled bar contained 8.1-11.3 ppb of benzene [27]. These studies illustrate how approximately half of the residents in these studies were exposed to more benzene indoors than outside [11].

Health implications
The highest average concentration modeled in Gainesville, Hall County was 2.82 µg/m3 or 0.88 ppb (CEP 1990). Measured concentrations at Newtown in 1997 ranged from 0.1 - 2.6 µg/m3 or 0.3 - 0.8 ppb. No adverse effects are known to occur in animals or humans exposed to less than 530 ppb benzene in air [48].

Acrolein

The levels of acrolein modeled by EPA in the Newtown community would not present a health threat if residents were exposed to similar measured concentrations.

Chemical properties
Acrolein is a breakdown product of 1,3 butadiene and it is used to make other chemicals and pesticides. It is found in some livestock feeds and pesticides [49]. It is also used to control the growth of algae, weeds, and mollusks in recirculating process water systems, water towers, water treatment ponds, oil wells, and petroleum fuels. It is also used in the processes of the leather tanning industry, laboratories, metal manufacturing, perfume manufacturing, and the manufacturing of a number of different chemicals.

Acrolein is a gaseous constituent of cigarette smoke and has been detected at levels equivalent to 3-220 µg (micrograms) per cigarette. Acrolein is formed when fats are heated. It has also been found in foods and products such as raw cocoa beans, volatiles from cooked mackerel and white bread, and vegetable oils, wine, whiskey, and lager beer [49].

Health implications
At the highest levels modeled by the CEP (0.13 µg/m3 or 0.057 ppb) and NATA (0.087 µg/m3 or 0.038 ppb), it is not expected that residential exposure to acrolein will result in adverse health effects. Acrolein was not measured by ATSDR or Georgia Environmental Protection Division in past sampling efforts. Acrolein has been observed to cause non-serious effects in humans (irritated eyes, nose and throat) at exposure levels between 170 ppb to 430 ppb. Residents would have to be exposed to three thousand times the modeled concentrations of acrolein to experience these types of non-serious health effects [49].

Manganese

ATSDR does not expect any adverse health effects to arise from exposure to the levels of manganese measured or modeled in the Newtown area.

Chemical properties
Manganese is a naturally occurring substance and ubiquitous (common) constituent in the environment, occurring in soil, air, water, and food. Rocks containing high levels of manganese compounds are mined and used to produce manganese metal. This manganese metal is mixed with iron to make various types of steel. Some manganese compounds are used in the production of batteries, as an ingredient in some ceramics, pesticides, and fertilizers, and in dietary supplements. Eating a small amount of manganese each day is important in maintaining your health. The amount of manganese in a normal diet (typical American diet is between 1-10 mg/day) seems to be enough to meet a person's daily need. Consuming too little manganese can interfere with normal growth, bone formation, and reproduction.Too much manganese can also cause serious illness.

The main sources of manganese in the air are industrial emissions, combustion of fossil fuels, and reentrainment of manganese-containing soils [50-55]. The principal sources of industrial emissions are ferro alloy production and in iron and steel foundries. The principal sources of combustion emissions are in power plants and coke ovens [50,52,53].

Above-average exposures to manganese are most likely to occur in or near a factory or a waste site that releases significant amounts of manganese dust into air. Manganese is also released into air by combustion of unleaded gasoline which contains manganese as an anti-knock ingredient. Since these releases are particulate in nature, the fate and transport of the particles are determined mainly by the wind and the size and density of the particles [56].

Health implications
The highest estimated levels of manganese in ambient air was 0.08 µg/m3 based on ATSDR's air modeling. The highest level measured by the Fair Street School monitor was 0.022 µg/m3. ATSDR reviewed the scientific literature to identify the lowest level at which health effects were observed in humans (LOAEL) exposed to manganese in ambient air. The lowest LOAEL was 27 µg/m3, which is over 330 times greater than the concentration measured in the Newtown community [56]. All levels of manganese either measured or modeled were more than two orders of magnitude lower than the lowest effects levels.

n-Hexane

n-Hexane does not pose a health threat to residents based on data reviewed by ATSDR.

ATSDR did not identify n-hexane as a contaminant of concern during modeling or analysis of air monitoring results; however, it is a great concern for residents because it is used by Cargill, Inc. This information is provided to give residents information about n-hexane and what health effects can be expected due to the levels of exposure modeled in Newtown.

Chemical properties
n-Hexane is a chemical made from crude oil. Pure n-hexane is a colorless liquid with a unpleasant odor. It evaporates very easily in air, but does not dissolve well in water. It is flammable and can be explosive. It is usually mixed with other solvents to extract vegetable oil from crops, such as soybeans (this is why Cargill, Inc. uses Hexane), but has other industrial uses. It is present in gasoline as well as rubber cement in consumer products.

People can be exposed to small amounts of n-hexane while cooking with oils, breathing in ambient air near roads or in urban or industrial areas, or working in jobs that expose them to it. n-Hexane does not seem to cause cancer in humans, although is has been observed to cause other illnesses in high doses.

Health implications
The highest level modeled in the Newtown community was 14.72 µg/m3 (4.18 ppb). The lowest adverse effect level (LOAEL) in humans, or the lowest contaminant concentrations that have been observed to cause health effects in humans, at a chronic level, is 58,000 ppb. The highest level modeled here is 13,900 times lower than the LOAEL for chronic human exposure [57].

There was an acute incident that occurred in 1995 that residents believe was an accidental release of n-hexane that resulted in 25 residents visiting the local hospital. Over 100 residents were also evacuated from their homes. Residents reported that the exposure to the fumes resulted in respiratory discomfort, nausea, and burning, itchy eyes. The scientific literature reports that n-hexane exposure generally results in nerve disorders, with acute exposure to high levels (500,000-2,500,000 ppb) resulting in such health effects as numbness of hands and feet, and muscle weakness in the feet and lower legs. If it is severe, there is paralysis of the arms and legs. The lowest LOAEL for n-hexane is 58,000 ppb. Because residents reported symptoms that were not consistent with n-hexane exposure, it is possible that the exposure of area residents in 1995 was to a contaminant other than n-hexane. The compound that resulted in this event was never identified by state and federal officials.

Particulate Matter

Very sensitive residents may experience asthma attacks, difficult breathing, and aggravated emphysema due to exposure to urban air. However, the air quality in Newtown is at least as affected by mobile emissions (traffic) as it is by facilities, if not more so. Residents without pre-existing health conditions should not be affected by the levels of particulate dusts measured in Newtown.

Chemical properties
Particulate matter are fine dust molecules that originate from a variety of sources, including diesel trucks, power plants, wood stoves and industrial processes. The chemical and physical composition of these various particles vary widely. While individual particles in air cannot be seen with the naked eye, collectively they can appear as black soot, dust clouds, or grey hazes. Dust that is seen on cars or on the ground is evidence of particulates in air that have settled out. Those particles that are less than 2.5 micrometers in diameter are known as "fine" particles; those larger than 2.5 micrometers are known as "coarse" particles [58].

Fine particles result from fuel combustion (from motor vehicles, power generation, industrial facilities), and residential fireplaces or wood stoves. Fine particles are also formed in the atmosphere from gases such as sulfur dioxide, nitrogen oxides, and volatile organic compounds. Coarse particles are generally emitted from sources such as vehicles traveling on unpaved roads, materials handling, crushing and grinding operations, and windblown dust [58].

Health implications
Particulate matter is the term used for a mixture of solid particles and liquid droplets found in the air. Fine particles are of health concern because they easily reach the deepest recesses of the lungs. Batteries of scientific studies have linked particulate matter, especially fine particles (alone or in combination with other air pollutants), with a series of significant health problems.

The levels detected in Newtown, while not exceeding 24 hour PM2.5 EPA guidelines, did exceed annual average recommendations by a marginal amount. While ATSDR does not expect PM2.5 concentrations to cause serious health effects for residents, the levels reported could cause respiratory aggravation and exacerbate asthma for sensitive Newtown residents. For example, residents with asthma, emphysema, or decreased lung function could potentially experience discomfort on days when the particulate concentrations outside are significantly higher than health-based guidelines. However, this scenario is not generally the case in Newtown.

Based on the evaluation of the available site-specific data and modeled contaminant information, ATSDR concludes that particulate concentrations in air in and around the Newtown Community are unlikely to represent significant health risks.

Air quality in Newtown- Potential health effects of urban exposure

Although ATSDR does not expect health effects to occur from contaminants discussed in the previous section separately from one another, as a mixture these contaminants could potentially cause health effects at low levels. There are a number of studies that have analyzed the effect of ambient air on the health of people living in industrial and urban areas. These studies have documented associations between levels of common urban contaminants in air and the manifestation of health effects in area residents. EPA reports that despite major improvements in air quality over the past several decades, in 1997 there were still approximately 107 million people in the United States who lived in counties with monitored air quality above the national air quality standards [58].

Exposure to contaminants in urban air is associated with numerous effects on human health. The contaminants most likely to affect the health of residents in Newtown include: ground level ozone, nitrogen oxides (NOx), carbon monoxide (CO), volatile organic compounds (VOCs), especially formaldehyde, 1,3-butadiene, acrolein, benzene and benzene derivatives, as well as particulate dusts. ATSDR has identified on-road and off-road mobile sources as the major source of air pollution in the Newtown area. Mobile sources are the greatest contributing factor of each of these contaminants with the exception of particulate dusts. It is estimated that up to 30% of the automobiles on the road today produce the majority of emitted pollutants in the atmosphere [59].

Ground-level ozone is formed by the reaction of volatile organic compounds (VOCs) and nitrogen oxides (NOx) in the presence of heat and sunlight. It is formed easily in hot summer months. The VOCs and NOx that form ground-level ozone are emitted by a variety of sources, the most notable being motor vehicle and some industries (power plants, dry cleaners, refineries, etc.). Ground-level ozone has been associated with respiratory irritation (coughing, itchy throat, and a tightness in the chest), decreased lung function (making it more difficult to breathe), aggravated asthma and other lung diseases (like emphysema and bronchitis), and damage to the lining of the lungs [60-62].

Nitrogen oxides (NOx) can irritate the lungs, cause bronchitis and pneumonia, and lower a person's resistance to respiratory infections. VOCs like benzene, 1,3-butadiene and its breakdown product acrolein, and formaldehyde are commonly associated with car exhaust. Studies characterizing concentrations and exposure to numerous VOCs suggest that concentrations for most VOCs are higher indoor compared to levels found outdoors [11,40,63-67]. This is most likely because most people spend between 70 and 90 percent of their time indoors [63,68,69]. Also, VOCs are ubiquitous (common and widespread) throughout the environment, often in relatively high concentrations in urban areas. For example, in the EPA's Assessment System for Population Exposure Nationwide (ASPEN) study, model results showed that outdoor concentration estimates for benzene and formaldehyde were greater than the cancer benchmark concentration in over 90 percent of the census tracts [63].

Carbon monoxide (CO) is formed from the incomplete burning of carbon in fuels. It is a component of automobile exhaust, which contributes about 60 percent of CO nationwide. EPA (1997) reports that as much as 95 percent of all CO emissions in cities come from automobile exhaust. In humans, low-level exposures can result in headaches, fatigue, and flu-like symptoms. Because CO reduces oxygen in the bloodstream, the health threat from CO exposure is most serious for people who suffer from cardiovascular disease.

Particulate matter has many sources in the environment, such as factories, automobiles, construction, and windblown dust. Exposure to larger particulate dusts is associated with aggravated respiratory effects, such as asthma. Small, fine particles are associated with increased visits to hospitals for heart and lung disease, decreased lung function, and potentially premature death [58,62].

A study very similar to ATSDR's evaluation in Newtown attributed 70 percent of cancer risk in the community with polycyclic organic matter, 1,3-butadiene, formaldehyde, and benzene. The study revealed that these contaminants and most of the cancer and non-cancer risk originated from area and mobile sources [68]. Furthermore, the study concluded that although these contaminants are ubiquitous in the environment, that potential cancer and noncancer risks by ambient exposures were geographically concentrated throughout the study area in large urban areas with high population and automobile density. Interestingly, the study also noted that mobile emissions constituted over half of the source contributions to outdoor concentrations of acrolein (59%), benzene (60%), 1,3-butadiene (81%), formaldehyde (51%), and polycyclic organic matter (77%).

As a mixture, studies have reported that these contaminants can cause a number of health effects in area residents. Many studies have associated air pollution levels with reduced pulmonary function, respiratory illness and symptoms, and even increased mortality [70-77]. In adults and children, air pollution has been associated with increased emergency room visits and hospital admissions due to asthma [61,63,77,78]. For example, Wong et. al. (2001) noted a consistent and statistically significant association between asthma admissions to the hospital and daily levels of sulfur dioxide, nitrogen dioxide, and particulate dusts. Strachan (2000) reports that after an episode of high particulate and nitrogen dioxide pollution, mainly from automobiles, occurred in London (1991), that asthma admissions increased very slightly; however, other respiratory outcomes, including chronic bronchitis and emphysema among the elderly, had a larger increase in admissions. Some studies suggest that air pollution can cause people to become more sensitive to allergens in air and that air pollution may be a significant factor in the development and exacerbation of asthma [78]. Others acknowledge the occurrence of 'asthma days', which are days attributed to high outdoor allergen exposures. The effects of outdoor air pollutants on people with asthma attacks have been poorly quantified by epidemiologic studies [78,79].

Unfortunately, little is known about how these pollutants interact in order to fully evaluate health risks posed by cumulative air toxic exposure. However, many studies, like those mentioned above, have suggested that respiratory diseases and pulmonary dysfunction are sometimes a result of or exacerbated by exposure to ambient air pollution.

It is possible that Newtown residents could manifest symptoms like those discussed previously given the industrial area they reside in.

ATSDR's Child Health Initiative

Children are at greater risk than adults for certain kinds of exposure to hazardous substances emitted from waste sites and emergency events. They are more likely to be exposed for several reasons:

  • The developing systems of children can sustain damage if toxic exposures occur during certain growth stages.
  • Children play outside more than adults, and therefore have an increased likelihood of coming into contact with chemicals in the environment.
  • Since they are typically shorter than adults, children breathe more dust, soil, and heavy vapors close to the ground.
  • Children are also smaller, resulting in relatively higher doses of chemical exposure per body weight.

ATSDR evaluated the types and quantities of air contaminants detected in the community to determine how children might be exposed and whether levels detected in the community could be associated with any reproductive or developmental effects. ATSDR uses health based guidelines protective of the most susceptible population exposed to air contamination; children and the elderly. Although no levels of measured contaminants would be expected to result in adverse health effects for children, it is possible that unmeasured criteria pollutants could effect their respiratory health. The highly trafficked area near the community and numerous facilities may produce enough air pollution to exacerbate asthma in children. However, more data would be needed to determine whether or not this is occurring.



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