II. BACKGROUND AND STATEMENT OF ISSUES

II. BACKGROUND AND STATEMENT OF ISSUES

This investigation provides a review of potential exposure pathways to chemicals from the OCRR site as well as a review of the pattern of cancer in East Bridgewater through comparison of the incidence of eight cancer types with the incidence of these cancers in the state of Massachusetts as a whole. Additionally, available information about risk factors, including environmental factors, related to the development of cancer was evaluated. To evaluate concerns about potential environmental exposures from the OCRR site, MDPH contacted Region 1 of the United States Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (MDEP) to obtain and review available environmental data. Information about Alloy Castings Company was obtained from the MDEP and the East Bridgewater Board of Health; however, there was no available environmental data related to the company. Therefore, evaluation of community concerns in relation to this company was limited to a qualitative evaluation of the geographic pattern of cancer diagnoses in neighborhood areas surrounding the company.

Cancer incidence rates were calculated for the town of East Bridgewater during the years 1982–2000, the time period for which the most recent and complete cancer incidence data were available from the Massachusetts Cancer Registry (MCR) at the initiation of this analysis. The town of East Bridgewater is divided into three smaller areas, or census tracts (CTs). A census tract is a smaller geographic subdivision of a city or town designated by the United States Census Bureau. Because age group and gender specific population information is necessary to calculate cancer incidence rates, the census tract is the smallest geographic area for which cancer rates can be accurately calculated. Both the OCRR site and Alloy Castings Company are located in CT 5231, in the southwest area of the town. East Bridgewater CT 5231 comprises an area of approximately 25 square kilometers and has a total population of 2,872 (U.S. Census Bureau 2000). Refer to Figure 1.

The results of this descriptive analysis can be useful in identifying cancer patterns or trends in a geographic context, to determine if a common etiology (i.e., cause associated with the development) is possible, and may serve to identify areas where further public health investigations or actions may be warranted. Descriptive analyses may also indicate that an excess of known risk factors associated with a disease, such as environmental exposures, exists in a certain geographic area. This descriptive analysis of cancer incidence data cannot be used to establish a causal link between a particular risk factor (either environmental or nonenvironmental) and the development of cancer. In addition, this analysis cannot determine the cause of any one individual's cancer diagnosis. The purpose of this evaluation is to report the findings on the patterns of cancer in East Bridgewater, with a particular focus on the neighborhoods in the vicinity of the OCRR site and the Alloy Castings Company, and discuss them in the context of the available environmental information to determine whether recommendations for further public health action are needed.

III. OBJECTIVES

The specific objectives of this investigation were as follows:

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  To evaluate opportunities for environmental exposure(s) to nearby residents to contamination identified at the OCRR site;
  

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  To evaluate the incidence rates of eight cancer types (leukemia, non-Hodgkin’s lymphoma and cancers of the bladder, brain and central nervous system [CNS], breast, kidney, liver, and lung and bronchus) in East Bridgewater and in areas near the OCRR site and Alloy Castings Company to determine if cancer is occurring more or less often than expected;
  

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  To evaluate the geographic distribution of individuals diagnosed with cancer in East Bridgewater in order to determine if there are any patterns in particular areas of town or in relation to areas of potential environmental concern;
  

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  To review available descriptive information from the Massachusetts Cancer Registry (MCR) for individuals diagnosed with cancer in East Bridgewater to see if there are any particular characteristics related to known or suspected risk factors, including environmental factors, for developing these diseases; and
  
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  To discuss the results of this evaluation in the context of the available scientific and medical literature on cancer and the contaminants of concern in order to determine whether further investigation or public health action is warranted.