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Calculating Risks from ambient air concentrations:

Carcinogenic (Cancer) effects:
For carcinogens (cancer-causing substances), risks are estimated as the probability over time that an individual will develop cancer over their lifetime as a result of exposure or a potential carcinogen. In other words, the additional risk a person may experience due to exposure to a contaminant that he would of otherwise not experienced.

A "slope factor" was used to calculate risk for contaminants of concern in Newtown. A slope factor is a very conservative estimate of probability that a person will develop cancer as a result of exposure to a specific chemical. It is assumed, when calculating cancer risk, that the slope factors is directly related to the intake concentration of the contaminant of concern (that at the exposure goes up or down, the slope factor goes up or down accordingly). Most simply, the cancer risk here was calculated with the following equation:

Risk=CDI x SF

Risk= probability of a person developing cancer

CDI= Chronic daily intake averaged over 70 years

SF= slope factor

This calculation is very conservative and assumes the worst case, namely that an individual is exposed for 24 hours a day, 365 days a year, every day of their lives. This gives us confidence that the "true risk" of residents will not exceed the risk estimate derived through the use of this model and is most likely less than predicted.

Non-cancer effects:

The measure used to describe the potential for a person to experience non-cancer adverse health effects is different than the way cancer risk is calculated. This number is not a probability of developing disease with lifelong exposure, but rather a ratio of the measured contaminant concentration (exposure level) divided by the reference dose. A reference dose is the highest dose at which no non-cancer effects have been observed in scientific studies. This ratio is called the hazard quotient. The formula for this calculation is as follows:

Non-cancer hazard quotient= E/RfD

E= exposure level (measured contaminant in air in this case)

RfD= reference dose

The noncancer hazard quotient assumes that there is a level of exposure below which it is unlikely for even sensitive populations, like the elderly and children, to experience negative health effects. If the exposure level (E) exceeds this threshold they, there may be a concern for potential effects. In other words, if the ratio is greater than one, non-cancer risk is higher than the reference dose, and if it is less than one, it is lower. A hazard quotient below one means that the measured level in the ambient air of the community is unlikely to cause adverse health effects , but that does not necessarily mean a hazard quotient above one will result in health effects. Toxicologists and the health assessor must look at the concentrations of the contaminant in air and research the relevant scientific literature to determine if negative health effects are likely at the maximum concentration measured in the community.

This explanation is intended to describe the methodology of the calculation of risk from cancer and non-cancer illnesses given site specific measured concentrations. Thus, for our purposes, these numbers are not conclusively accurate. Risk calculations are accurate when they are based on true measurements, and are used as a screening only when they are based on modeled measurements. This investigation used these calculations as a screening tool only, to identify significantly elevated hypothetical risks in this area from facility emissions. True risk can only be calculated with real and not modeled data.

ATSDR evaluated cancer trends in this community in depth with community-specific data in the first Newtown PHA released last year. ATSDR did not identify statistically significant increases of cancer diagnosed in the community.


Sampling results for ambient air in and around the Newtown Community as reproduced from the March 2001 Final Public Health Assessment for the Newtown Community

Table 1. Contaminants exceeding ATSDR comparison values from Georgia DNR air monitoring*

1997 Air Monitoring Data from the Fair Street School Monitor

Contaminants range of detection levels (µg/m3)* detection frequency total number of samples comparison value*
benzene 0.1-2.6 5 21 .25 µg/m3 EPA RBC
methylene chloride 3.8-46.9 2 21 4.1 µg/m3 EPA RBC
hexachlorobutadiene 7.5-7.5 1 22 .09 µg/m3 EPA RBC
arsenic 0.002-0.018 12 22 .0045 µg/m3 EPA RBC
cadmium 0.00071-0.0042 2 22 .0001 µg/m3 EPA RBC

*Comparison value used is in micrograms per cubic meter, EPA RBC are Environmental Protection Agency Risk Based Concentrations.

Table 2. Contaminants of Concern for ATSDR Exposure Investigation of Air in and around the Newtown Community

Contaminants Exceeding ATSDR Comparison Values in Analysis of SUMMA Canisters

contaminant range of detection levels (ppb)1 detection frequency total number of samples comparison values
methylene chloride2 0.34-5.5 10 10 300 ppb ATSDR Chronic EMEG
benzene 0.65-23 6 10 0.1 ppb ATSDR CREG
4 ppb ATSDR Intermediate EMEG
2-butanone 1.2-1200 5 10 1000 ppb ATSDR chronic inhalation RMEG/RFC
toluene 1.1-1300 9 10 400 ppb ATSDR chronic EMEG
freon 11 0.28-0.38 10 10 No Cvs are available
freon 113 0.60-0.89 8 10 No Cvs are available
4-ethyl toluene2 0.78-0.79 2 10 No Cvs are available

1 ppb=parts per billion
2 The highest concentration of this contaminant was in a sample blank. This suggests other levels of this contaminant that were measured may be inaccurate.

Table 3. Particulate dust concentrations, Georgia EPD 2000

2000-2001 Ga EPD PM 2.5 Respirable Dusts in Air (µg/m3)1


concentration range

24-hour average concentration EPA recommended levels
february 2000 7.9-24.4 15.9 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
march 2000 7.1-19.0 14.1 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
april 2000 4.5-25.8 15.3 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
may 2000 8.1-25.8 15.4 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
june 2000 12.9-43.4 21.8 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
july 2000 10.7-34.8 23.8 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
august 2000 9.7-34.4 27.1 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
september 2000 4.5-28.8 19.2 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
october 2000 5.2-24.6 16.8 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
november 2000 4.6-29.5 18.6 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
december 2000 8.0-17.4 12.1 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
january 2001 5.7-26.4 12.9 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
february 2001 9.1-32.9 18.1 65 µg/m3 (24 hour)
15 µg/m3 (annual average)
march 2001 7.5-28.8 17.7 65 µg/m3 (24 hour)
15 µg/m3 (annual average)

1 µg/m3= micrograms per cubic meter of air


Response to Public Comments

The Agency for Toxic Substances and Disease Registry (ATSDR) issued a public health assessment draft for public comment on February 12, 2002 for the Newtown Community in Gainesville, Georgia. Between February 12, 2002 and April 11, 2002 the public had the opportunity to provide comments on the draft public health assessment. Since that time, ATSDR has addressed comments and reader evaluations from residents (via the Newtown Florist Club), The Lawyer's Committee for Civil Rights Under Law, and the Georgia Department of Natural Resources, Division of Air Quality. These comments/questions are presented below. Comments are printed in italics.

Comments from Ga DNR, Division of Air Quality

  1. Comment: "The Georgia EPD would like to comment on the discussion concerning the siting of the air toxic monitoring site in Gainesville. Several factors must be considered in siting an ambient air-monitoring site, including the factors of access, security, power supply, and safety as stated in the report. However, these are not the critical parameters in siting an ambient air-monitoring site. The most critical factors include area of representativeness, unobstructed airflow, and the availability of an area for establishing a site. Establishing a monitoring site is a compromise activity taking into account various issues in order to establish the best possible site. The Fair Street School site is the result of those compromises.
  2. Establishing an air monitoring site in the area suggested in the report indicates that the ATSDR interest is in conducting a microscale project. Data collected on a microscale means that the data is only pertinent to an area ranging from the immediate vicinity to 100 meters. Since Newtown is larger than 100 meters, the data from the microscale site would not apply to the whole community. This is reflected in the maps included in the report that show differences in concentrations of various pollutants and cancer risks across the Newtown area. In order to characterize the air quality for the whole Newtown area, a neighborhood (medium) scale project was indicated. Neighborhood scale site provide data that is representative of an area ranging from 100m to 0.5 kilometers. The Fair Street school site is located within that area. The ATSDR report indicates that the Fair Street School site met the objectives of a neighborhood scale project and did well characterizing the annual exposure of the residents in Newtown and surrounding areas."

ATSDR Response: Because the air quality measured at a single site is based on a sample of air from a very small volume, it is useful to know over how large an area this value can be considered representative. The concept of "representativeness" is the idea that the physical dimension of the area within which a monitoring station is located that pollutant concentrations are reasonably similar. 'Similar' refers to extreme concentrations that are within 25% of the mean for the area. If greater variability (larger values) occurs, the area would need to be subdivided until this similarity criterion is met. The modeled concentrations indicate a difference of at least 100% for arsenic from Conagra and between 400 and 1000% for manganese from Purina between the community and the Fair Street School air monitor.

ATSDR agrees that the "Middle Scale" approach is appropriate here. Middle Scale defines the concentration typical of areas up to several city blocks in size with dimensions ranging from approximately 100 m to 0.5 km. Upwind and downwind monitors can be placed in this range, however it would be more effective (when looking for maximum impact to a population) to place the monitor in a predominately downwind location or in a location between the sources of concern and community of concern.

  1. Comment: "Another critical parameter not mentioned in the report is unobstructed airflow. The Newtown Community is densely built, and generally does not allow for free airflow. However, several sites in the Newtown Community were investigated as possible sites for air monitoring including the playground. These sites either did not meet physical siting criteria or we were not given permission to establish a site on the property. The Fair Street School meets all of the physical siting criteria of unobstructed airflow, probe height, and availability."

ATSDR Response: Residents report that they lobbied Georgia DNR to place an air monitor within the Newtown Community. Residents did not perceive an effort by Georgia DNR to locate the monitor within the community.

  1. Comment: "Since the modeling, with its associated assumptions, indicates minimal differences in concentrations between a site located in the suggested area and those detected at the Fair Street School site, the Georgia EPD will have difficulty in justifying moving the site or establishing a new site in the suggested area."

ATSDR Response: As mentioned in Comment 1, the modeled concentrations of contaminants in air are significantly different between those modeled in the Newtown Community and those modeled at the Fair Street School monitor. Arsenic concentrations were twice as high in the community, manganese concentrations were between 4 and 10 times higher in the community, and hexane concentrations were between 2.5 and 5 times higher in the community than at the location of the Fair Street monitor.

However, as Ga DNR indicated, the purpose of the air monitor is no longer to measure the emissions that Newtown residents are exposed to.

Comments from the Newtown Florist Club

  1. Comment: "Considering the fact that ATSDR is not a regulatory agency, their report will still carry a substantial weight, and therefore the ability to create barriers to showing a connection to industry emissions and the increased occurrence of illness. When the state [Georgia] released its study early in 1991, it attributed high levels of cancer and illness to lifestyle choices. However, the study failed to document any investigations which could support that conclusion. The general populace and public policy makers adopted the conclusion as fact. In the current report they state inexplicably that current emissions are not likely the proximate cause of cancers or illness in the Newtown Community..."

ATSDR Response: ATSDR was unable to obtain an original copy of the 1990 study of cancer incidence in the Newtown Community by the Georgia Department of Human Resources (Ga DHR). Ga DHR could not locate the entire original document for ATSDR's review, but ATSDR was able to review the summary report. The summary report associated elevated mouth and throat cancer to lifestyle choices of residents. Nowhere in the summary of the study is there mention of an investigation of lifestyle choices of residents, nor was ATSDR able to obtain a questionnaire used in the analysis of lifestyle of residents. If, as residents allege, these behaviors were not investigated, but associations were made between disease and lifestyle on an assumptive basis, the study conclusions should be regarded as incomplete.

Because of the high level of concern residents had for the validity of this study, ATSDR reproduced an investigation of cancer incidence in the community. The findings of this study are presented in the first Newtown Public Health Assessment (March 15, 2001), pages 14-15 and pages I-9 through I-14. This analysis was of cancer incidence in the community from 1980 through 1996 (all data that were available at the time). The cancer rates in our analysis were not statistically significantly elevated above other African-American populations in the state of Georgia or in the National Surveillance Epidemiology and End Results (SEER) study states and cities. Moreover, there was no statistically significant elevation of a specific cancer or family of cancers; the patterns of cancer follow the trends of the comparison populations and common cancers in the United States.

The most frequently occurring cancers in this community were those of the prostate, colorectum, breast, and cervix. These cancers are also among the most commonly reported cancers in the United States, and most are very common in aging populations. The median age in Newtown is about 5 years older than in the county (40.2 and 35 years of age, respectively). Incidence and death rates from cancer increase markedly with advancing age, so a population with more elderly residents is likely to experience a higher incidence and death rate from cancer. With the exception of mouth and throat cancers, the cancer rates noted are within average ranges given the age and sex distribution of Newtown's population. No new cancers of the mouth and throat have been diagnosed in the community since 1987.

"In the current report they state inexplicably that current emissions are not likely the proximate cause of cancers or illness in the Newtown Community..."

ATSDR Response: ATSDR acknowledges in the two Newtown Public Health Assessments that other illnesses besides cancer could be a result of emissions in the area. It has been verified that Lupus is elevated in this community (Kardestuncer and Frumpkin, 1997), and anecdotal evidence from many residents indicates that respiratory illness and asthma are also very common. In this Public Health Assessment, there is a section devoted to the many health effects that are observed in urban populations. Many of the respiratory ailments and diseases reported by residents may be associated with exposure to urban air. At this time, Lupus has no well established environmental causes. See page I-9 through I-14 of the 2001 Public Health Assessment for a further discussion of lupus and cancer.

  1. Comment: "The report should also state explicitly and in no uncertain terms that the findings preclude the fact that an unknown emission or agent which was released before 1987, when industry came under compliance under the Toxic Release Inventory, could be the cause of the increased level of cancer, lupus, and other diseases. In fact, it is very possible that an agent could have been present and we are just beginning to see the latent effects of that agent."

ATSDR Response: ATSDR agrees with Comment 5 completely. We attempted to identify this limitation in both the Summary and Conclusions sections of both Public Health Assessments. To make the point more clear in this document, bullet 4 of the Conclusions section will be moved to the beginning of the section. Paragraph 5 on page 1 of the Summary is devoted entirely to this point.

  1. Comment: "How did ATSDR come to the conclusion that most pollution is from mobile emissions, based on the fact that the air monitor is located in an area where 90% of the time the wind is blowing away from industry in the Newtown Community?"

ATSDR Response: This conclusion was based on emissions inventory of these facilities and three independent air models. It was not based on data from the monitoring station!

  1. Comment: "We feel ATSDR should be pressured to have EPD move the air monitor closer in the Newtown Community where industry is located."

ATSDR Response: ATSDR agrees that the monitor should be moved. However, ATSDR has no authority to require EPD to move the monitoring location. As mentioned on page 18, paragraph 2, when ATSDR made its recommendation to the state, we were told the "purpose of the monitor had changed", and that its purpose was no longer to measure ambient air quality for Newtown residents, but was now a "regional air quality monitoring station".

  1. Comment: "Under study methods you indicate that the study sought to determine whether or not cancer rates in the community are statistically different compared to US rates for African-Americans. If industry is generally located more in African American and poor neighborhoods, why wasn't a comparison made to white populations of similar size?"

ATSDR Response: It is most appropriate to compare a community of primarily one ethnicity to another community of the same ethnicity. The reason for this is because there are extreme variations in genetics, diet, behavioral patterns, health practices, lifestyle choices, and disease rates between ethnicities. Overall, African Americans are more likely to develop cancer than persons of any other racial or ethnic group. For example, African American women have a higher incidence rate of colon and rectum cancers than Caucasian women. However, Caucasian American women have a higher rate of breast cancer than African American women. African American males have a higher incidence rate of prostate cancer than any other racial group. American Indians have lower cancer rates than any other ethnic or racial group. This illustrates the difficulty in deriving a "normal rate" by using rates of other races/ethnicities.

Unless a comparative study is conducted, epidemiologic studies use populations of the same race when defining "normal rates" in a population. Newtown's cancer rates were similar to other African American populations (urban and rural, exposed and unexposed communities) across the United States (SEER database, 2000). Since the cancer rates in Newtown are within normal ranges in the US population, and contaminants in air that have been measured are not at levels that have been observed to cause cancer, ATSDR has concluded that the two do not appear to be related.

Comments from the Lawyers' Committee for Civil Rights Under Law

  1. Comment: "ATSDR's Assessment is void of any environmental justice considerations or recommendations. We, therefore, recommend that ATSDR incorporate its environmental justice responsibilities into its Assessment. Specifically, ATSDR must do more to address adverse, disparate impacts in Newtown. The Executive order itself requires that ATSDR implement its programs, policies, and activities that affect human health or the environment so as to "identify", "address", "and "ensure" that they do not result in disproportionately high and adverse effects on minority and low-income populations. Moreover, ATSDR's own environmental justice program purports that "preventing" adverse health effects and environmental injustices in minority populations is a priority."

ATSDR Response: The documents written for the investigations that have taken place in this community were written in accordance with Agency guidance. The excerpt above, from Executive Order 12898, was intended for the regulatory agencies that have authority and jurisdiction to enforce environmental rules, permits for facilities, and the siting of facilities. ATSDR is an advisory rather than a regulatory agency, and therefore can only make recommendations to enforcement agencies (such as USEPA and Georgia EPD). Since ATSDR is not a regulatory agency, it cannot enforce laws or regulate facilities.

ATSDR has followed Agency guidance on environmental justice issues. These are listed below with examples:

  • Demographics: To develop a comprehensive demographic profile of communities living near hazardous waste sites and other sources of hazardous substances.

ATSDR thoroughly reviewed and presented demographic information in the first Newtown PHA released Final on March 15, 2001. This information was stated briefly in the current PHA. Maps and tables regarding demographics can be found in Appendix B of both documents.

  • Health Studies and Applied Research: To determine the relationship between identified adverse human health outcomes and hazardous substances in disadvantaged communities and persons of color.

The relationship emphasized in the above goal was the basis of over three years of research by the current Newtown Community Investigation Team.

  • Community Involvement and Risk Communication: To develop and execute environmental risk communication and education programs to mitigate and prevent adverse health effects from hazardous substances in disadvantaged communities and people of color.

ATSDR has been extremely pro-active to communicate its findings and progress to the Newtown Florist Club and other community members by using newspapers, fact sheets, mailouts, meetings, and frequent telephone calls to the petitioner. In addition, a health education effort ("Health Fair") was completed in September 2002.

  • Training and Education: To increase the numbers and racial and ethnic diversity of persons in professional disciplines encompassing environmental public health. This includes assisting with curriculum development in academic institutions, faculty support through research projects, seminars and workshops in toxicology and other disciplines, and short-term training for professionals in disciplines related to identifying and preventing environmental hazards.

This goal is not related to site specific health assessments, but relates to the many programs and grants ATSDR participates in to increase the participation of minority health professionals in environmental medicine.

ATSDR has done everything within its power and authority to assist the Newtown Community, and has made recommendations accordingly.

  1. Comment: "ATSDR may suggest that its environmental justice responsibilities are satisfied by discussing the community's demographics in the Assessment or recommending future activities such as conducting health education activities in the community. That response, however, is inadequate. While it is true that ATSDR's acknowledgment of the demographics of the affected community may "identify" an environmental justice issue, its proposal to conduct health education neither "addresses", "ensures" against, nor "prevents any adverse disparate impacts on Newtown. This deficiency alone demands that ATSDR revise its Assessment to adequately respond to the existing adverse disparate impacts in Newtown by, at a minimum, accurately assessing the true risks of the community."

ATSDR Response: In addition to our response for Comment 9, ATSDR would also like to suggest that health risk of residents living in Newtown has been investigated as thoroughly as available data would allow. Rates of cancer, Lupus, and the incidence of respiratory conditions, possibly associated with residential exposure to urban air, have been evaluated in both the first and second assessment. ATSDR used all available data, and at times requested additional data, to complete this investigation.

  1. Comment: "We agree that a proper assessment of the current risks posed to Newtown residents requires an assessment of past historical exposure. This is particularly important with respect to the Newtown Community for two reasons. First, many of Newtown's residents are longtime residents, who have lived in the neighborhood since the 1936 tornado. For that reason, the median length of residence is twice the median of the county, over 18 years compared to 9 years respectively. In addition, more than half of its residents are over 65 years old. Indeed, this longtime residency, with respect to Newtown, also means longtime exposure."

ATSDR Response: Please note (second to last sentence): census data indicate that approximately one-fifth of the community is 65 years of age or older, not one-half as indicated above.

ATSDR discusses historical exposure being an important consideration repeatedly in both health assessments. However, there are no environmental data to assess historical exposure prior to 1986. Cancer data were only available from 1980 to present. Neither of these measurements indicate a current significant threat to human health, nor an elevated pattern of cancer. ATSDR did estimate 30 years of constant exposure over a 70-year lifetime when calculating cancer and non-cancer risk (i.e., cancer risk, hazard quotient and hazard index), which are theoretical cumulative risks from multiple contaminants. These risks were not elevated above risks from other similar cities and much lower than larger cities, including Macon and Atlanta.

  1. Comment: "Second, an assessment of past exposure is crucial given the history of industrial development in Newtown. As noted by ATSDR, "the community was built over a landfill in 1936," and "is located in an industrial and commercial area." ATSDR specifically notes that "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." What ATSDR fails to note, however, is the time period in which these facilities began operating in Newtown. The largest and closest facilities to the community, such as Purina and Cargill, began operating in the mid 1950s. This long-term exposure together with the longtime residency proves that an accurate evaluation of past exposure is critical to a proper assessment of risk in the Newtown Community."

ATSDR Response: See the response to Comment 11.

  1. Comment: "Although its apparent that assessing historic exposure is necessary in determining true risk in Newtown, ATSDR's Assessment does not do so. Historic exposure was evaluated only by simulated and estimated data, both of which are extremely limited. Only emissions and data between 1983 and 1998 were reviewed. As a result, the Assessment could not accurately predict their potential impact on past, current, and future health conditions. Therefore, the conclusions that no health risks exist in Newtown, even with the qualifier limiting it to "currently or since 1986," is simply not accurate. This inaccuracy should be corrected."

ATSDR Response: For a discussion about ATSDR's review of "historic exposure" see the response to Comment 11.

Addressing the extent of data reviewed, we direct the reviewer to the first Public Health Assessment, released in March 2001. ATSDR reviewed a significant amount of measured data, as well as the "simulated and estimated data" mentioned above. This document evaluated existing cancer and lupus studies (1990, 1995); data from biological sampling (1994); and data from air (1997), groundwater (1993, 1994), tap water (1999), stormwater runoff (1993) and soil (1993, 1994) conducted by the Georgia Department of Natural Resources, the Georgia Department of Human Resources, the Georgia State University, and the City of Gainesville Public Utilities Department. In addition, ATSDR conducted limited surface soil sampling in the community playground, and ambient air sampling in the area. ATSDR also collected and reviewed cancer incidence data for the Newtown Community from 1980-1996. (see Introduction paragraph on page 2). These data suggest that residents within the community are not, and have not been since 1986 (as far back as data would allow investigation), exposed to contaminants at levels of health concern in any of the media sampled. Furthermore, cancer rates do not suggest elevated rates of cancer in the community for at least the past 20 years. Lupus rates, as mentioned before, are elevated, however lupus has many suspected causes, with no well established environmental links.

  1. Comment: "We commend ATSDR for attempting to address cumulative exposure in its Assessment given that the Newtown Florist Club specifically petitioned ATSDR "to investigate the public health impact of combined industrial emissions on the Newtown Community." We are also pleased that ATSDR conceded to its inability to evaluate cumulative exposure, and also acknowledged that "a mixture of these contaminants [present in Newtown] could potentially cause health effects at low levels." Given the many contaminants in Newtown, residents suffer health effects due to the cumulative industrial area where they live."

ATSDR Response: Thank You. Indeed, residents living in any urban and/or industrial area have higher exposures due to the cumulative exposures in the industrial areas where they live (emissions, car exhaust, etc).

  1. Comment: "We also commend ATSDR for acknowledging that "little is known about how these pollutants interact in order to fully evaluate health risks posed by cumulative air toxic exposure." Yet, given the cumulative exposure in Newtown, ATSDR should have incorporated this acknowledgment within its conclusions. It did not however. Instead, ATSDR concluded that air pollution in Newtown "are not likely to cause health effects..." That conclusion is not supported by its own discussion."

ATSDR Response: ATSDR agrees that the lack of current knowledge on the health effects of mixtures of contaminants should be added to the conclusions of the document. This limitation has been added to the Conclusions section.

The reviewer should note that nowhere in this document does ATSDR claim that air pollution in Newtown is "not likely to cause health effects". ATSDR did conclude that "air contaminant concentrations resulting from routine releases of chemicals from industries in the area of the Newtown community are not likely to cause adverse health effects currently or since 1986" and that "based on 1990 and 1996 emissions, mobile sources including cars and trucks are creating the greatest health threat for Newtown residents". Furthermore, there is a section devoted to health effects residents may experience given their industrial and urban exposures (pages 29-31). ATSDR is confident about these conclusions because of the additive nature of the non cancer and cancer risks calculated by estimating worst-case situations for all emissions, contaminants, and all facilities.

  1. Comment: "For instance, ATSDR itself states that its "calculations assume residents are only exposed to each chemical separately." But immediately thereafter states "That is not the case in Newtown." Although it acknowledges the inconsistency between its calculations and the conditions, ATSDR nevertheless evaluates risk to residents due to exposure to eight chemicals separately. This single-chemical approach ultimately leads ATSDR to conclude that no significant health risks exist. That conclusion, however, is inaccurate because it fails to incorporate the cumulative exposure in Newtown and the uncertainty in evaluating that exposure."

ATSDR Response: The reader may have misunderstood the aforementioned Health Implications Section. The ATSDR model estimates cumulative or additive risk from all facilities, all chemicals emitted, for the theoretical 70 year lifespan of a resident. These risks are categorized into cancer and non-cancer risks (see appendices E and F). The Health Implications Section was intended to simply discuss individual risk posed by each contaminant. The Air Quality Section, which begins on page 29, discusses in detail what we know about how general urban exposures of emissions from all urban sources, including mobile sources and facility sources, affects the health of residents in those areas. In effect, that section addresses what we DO know about chemical mixtures in urban/industrial ambient air and their effect on humans.

The ATSDR air modeling, as well as the USEPA Cumulative Exposure Project and National Air Toxics Assessment models, calculate risk based on additive exposures of each contaminant. For example, the Hazard Index, as defined on page 11 determines "the cumulative effects of different chemicals". In other words, this measurement of exposure to acceptable or unacceptable levels of contamination adds the potential risk of each chemical to derive an overall risk to multiple chemicals. This index was calculated in all the models used to evaluate Newtown.

  1. Comment: "Uncertainty exists regarding cumulative exposure risks not only due to ATSDR's single-chemical approach, but also due to its failure to adequately assess the true risks posed by combinations of multiple chemicals. This is because chemicals in the environment, or in the human body, sometimes react synergistically with one another, such that the combined effect is far more severe than the sum of the individual impacts. Scientists estimate that approximately 5% of pollutants react synergistically, and "because there are so many chemicals, the synergistic possibilities are huge."
  2. If ATSDR has studied the effects of chemical synergies relevant to Newtown, ATSDR should consider them in its Assessment. ATSDR should thus adopt an approach to cumulative exposure that incorporates the chemical synergies wherever data is [are] available. This approach has been adopted in some environmental laws. Furthermore, ATSDR should consider further research into chemical synergies. We recognize the task of investigating all possible chemical synergies is unreasonable, although investigating the synergistic effects of some of the most common combinations of chemicals would be useful. In addition, the shortage of information in this area is one reason, given the cumulative exposure existing in the community, for adopting a precautionary principle with respect to Newtown."

ATSDR Response: See the ATSDR response to Comment 16 where the "single-chemical" discussion is addressed. ATSDR reviewed a significant amount of scientific literature to evaluate potential synergistic effects in the community. ATSDR did not locate studies of residential communities (similar to Newtown) chronically exposed to very low levels of these types of contaminants for comparison. Most synergistic effect studies of toxic exposure are from occupational studies.

The levels measured or modeled in Newtown are between 100 and 100,000 times lower than those known to cause health effects for each chemical. Even if risk to these chemicals were additive, they are highly unlikely to reach a level of discernable risk. What is known about the "urban soup" of chemicals including car exhaust and other mobile emissions, plant emissions and other facility emissions (including dry cleaners, vehicle body shops, etc.), and the potential health effects expected from this exposure are discussed on pages 29-31. Because ATSDR found mobile emissions to be a significant exposure in this community, it is appropriate to consider these emissions as a significant exposure source. ATSDR determined that mobile emissions were the most significant source of exposure in the community by comparing models that reviewed and included mobile emissions as a source of overall risk, and our model, which only considered risk from facility emissions. Through this mechanism, it was determined that chemicals from mobile emissions were predicted to be present at higher concentrations than those released from facilities. ATSDR also explained to residents that industrial emissions have decreased in some area facilities in excess of 400% since the late 1980s (see TRI information at ), and that newer, more effective pollution prevention controls have been installed for area facilities. In short, past exposure scenarios are likely to be much different than they are today.

  1. Comment: "We agree that a proper assessment of air quality and exposure in the Newtown community depends on the proper location of the air monitor. ATSDR's approach to this assessment is commendable. In particular, we are pleased that ATSDR agrees that the location of sources and meteorology are more important to where an air monitor is located than other factors such as availability, access, security, power supply, and safety."

ATSDR Response: ATSDR has not stated that "the location of sources and meteorology are more important to where an air monitor is located than other factors such as availability, access, security, power supply, and safety". We believe these factors are extremely important when siting the location of an air monitor. However, we also believe that a location satisfying these criteria as well as one that will better represent the exposures of the community can be found within the parameters of the area we identified on page 19 of our assessment.

  1. Comment: "We are concerned, however, that the air monitor will not be relocated by the Georgia Environmental Protection Division ("EPD"). This concern stems from EPD's decision to change the purpose of the air monitor. While the air monitor once was used to "understand [] the effects of various sources both for the anthropogenic and biogenic compounds on the ambient air quality in Newtown and for the health of the community," it has been changed to "monitor [] the air in the general Gainesville area." We question the reason for this change of purpose, and its meaning for Newtown. We recommend that ATSDR request a public statement from EPD explaining why the purpose of the air monitor was changed, and inform the EPA of it. We also recommend that ATSDR include within that request a demand that EPD move the air monitor to a proper location."

ATSDR Response: ATSDR has the same concerns as the reviewer regarding these issues. However, ATSDR has no authority to enforce regulations or make demands of the Georgia EPD. ATSDR's authority is to act as an advisory agency to state and federal partners, and in this case to make recommendations to move the monitor or place a new monitor in the area designated by our model to measure community exposures.

Per this recommendation, ATSDR contacted the USEPA to notify them of the change in the purpose of the monitor. USEPA Region 4 Office of Air Quality Planning and Standards informed ATSDR that Georgia EPD is entitled to change the purpose of the monitor at any time and that USEPA has no jurisdiction over state ambient air monitoring programs.

ATSDR invited Georgia EPD to comment on the change of purpose of the monitor and has submitted the following response, here to be included in the public record:

Several factors must be considered in siting an ambient air-monitoring site, including the factors of access, security, power supply and safety as stated by the commenter. However these were not the defining requirements for the establishment of the Newtown site. The Statement of Work goes into many siting requirements needed to obtain a representative sample. Because of the densely built area the siting criteria as described in 40CFR Part 58 Appendix E - Probe and Monitoring Path Siting Criteria for Ambient Air Quality Monitoring referenced in the Statement of Work could not generally be met in the area indicated in the report. Placing a monitor in an area where the samples may not be representative could give unreliable data. By siting the monitoring site at the school we were able to meet both the area of representativeness (neighborhood scale) and the requirements found in the referenced document.

The introduction section of the statement of work states that the air toxic monitoring would be conducted for a period of one year with data review and interpretation ongoing throughout the year. At the end of the year a decision would be made on the future of the site. The Fair Street School site was established and began taking samples in early 1997. Meetings were held on a quarterly basis with the Newtown community discussing the findings of the monitoring. At the end of the year the Division determined there was merit in the continuation of operating the Fair Street School site for comparison purposes to the rest of the Statewide Ambient Air Toxic network. The change in purpose has allowed and will allow continued monitoring in the Newtown area for an indefinite time. This continued monitoring provides information to the Newtown Community for a number of years instead of the one year originally proposed. The redesignation of the Fair Street School site does not change its area of representativeness (neighborhood). Moving the Fair Street School site will cause the historical data gathered and the comparison to the PM2.5 site data to be lost. The continuation of the monitoring allows for a yearly risk assessment of the area similar to the 1997 EPD assessment.


Agency for Toxic Substances and Disease Registry. Newtown Community Exposure Investigation. Spring 2000.

Dockery, D. Residential lead testing. City of Gainesville, Public Utilities Department, 1999.

Friddell, M. An investigation of environmental conditions at a previous landfill in the Newtown area of Gainesville, Georgia. Georgia Department of Natural Resources, Georgia Geologic Survey; 1993.

Geology 801B. Site characterization report at the former Newtown Dump, Gainesville, Georgia. University of Georgia Geology Department; June 1994.

Georgia Department of Natural Resources, Air Protection Branch. 1997 Priority pollutants monitoring station at the Fair Street School. January 1997-December 1997.

Kardestuncer, T and Frumpkin, H. Systemic lupus erythematosus in relation to environmental pollution: an investigation in an African-American community in North Georgia. Archives of Environmental Health, March/April 1997: 52(2): 85-90.

McKinley, T and Williams, D. Newtown neighborhood cancer investigation, Gainesville Georgia. Georgia Department of Human Resources, Office of Epidemiology, 1990.

Raw Data: Hair Sampling of 16 Newtown Residents. Morehouse School of Medicine, 1994.

Surface water runoff in the Newtown community of Gainesville, Georgia-priority pollutants scan and conventional pollutants analysis. City of Gainesville Public Utilities Department, 1995.

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