Cancer Incidence Rates in Eddy and Lea Counties

New Mexico, 1970-1994

Issued: April 6, 1998

INTRODUCTION

This study was conducted by investigators with the Epidemiology & Cancer Control Program, University of New Mexico Health Sciences Center (Table 1), under a contract with New Mexico State University (NMSU), with funding by the Carlsbad Environmental Monitoring & Research Program (CEMRP), under a grant from the U.S. Department of Energy (DOE) to NMSU (DE-FG04-91AL74167). This research is part of a larger CEMRP project to implement independent health and environmental monitoring in the vicinity of the WIPP, and to make the monitoring results available to all interested parties.

The purpose of this study was to present an assessment of baseline cancer rates in Eddy and Lea counties. Cancers related to exposure to ionizing radiation and hazardous chemicals were stratified by sex and ethnicity, and analyzed by (1) describing geographic variation in cancer incidence found in New Mexico for the period 1970 to 1992, and (2) describing temporal variation in cancer incidence in Eddy and Lea counties for the period between 1970 and 1994.

Cancer and Toxic Exposure

For an individual to experience adverse health effects from an exposure to a substance, the substance must be toxic to humans, the individual must come into contact with the substance, and the individual must come into contact with high enough concentrations of the substance for a long enough duration to cause a biological effect (OTA 1991). Exposure to chemically hazardous and radioactive materials is associated with a variety of acute and chronic health conditions such as irritation and burning of the skin, eyes, and respiratory system; organ and nervous system damage; exacerbation of pre-existing conditions such as infections and allergies; birth defects; and cancer (Sax 1981; Sax 1987). In addition, exposure to a combination of toxic and radioactive materials may result in compounded adverse health effects, and some chemicals sensitize tissues to radioactive materials (Mettler 1995). Of these adverse health effects, cancer, a group of diseases distinguished by the uncontrolled growth of abnormal cells, is of paramount concern.

About 1 in 3 people alive today will develop cancer (Brownson 1993); at least 8 million Americans presently living have had or do have the disease (ACS 1995). Cancer cells may be created when a cell undergoes a permanent change by internal means or outside exposure. If a cell is damaged by exposure to a carcinogenic substance and survives but cannot repair itself, it is permanently altered and has the potential to become cancerous. It is likely that most adults develop many altered cells in their lifetimes that don't become cancerous (Craighead 1995). However, if a cell becomes cancerous it ceases to react normally to signals from the body, and begins to multiply rapidly and destroy healthy tissue (ACS 1995). If this growth is not stopped by treatment such as surgery, radiation therapy, or chemotherapy, the cancer can be fatal.

The likelihood of developing cancer increases with age (ACS 1995); Americans over the age of 65 have 10 times the risk of developing cancer than Americans under 65 (NCI 1993). In addition, in the US, men have a higher risk of developing cancer than women; blacks have a higher risk than whites; and Hispanics, American Indians, and Asians have a lower risk than other ethnic and racial groups (NCCDPHP 1992). However, there are some exceptions. For instance, some types of cancer occur frequently at a younger age, such as leukemia, Hodgkin's and non-Hodgkin's lymphoma, and cancer of the brain and nervous system, kidney, and bone (NCI 1993; Schofield and Cotran 1994; ACS 1995); females have a higher risk than males for particular cancers, such as thyroid cancer (NCI 1993); and American Indians have higher incidence rates for stomach, cervical, kidney, and gallbladder cancer than non-Hispanic whites (NCCDPHP 1992).

Other factors affecting the risk of developing cancer include tobacco use; lifestyle; diet; occupational and other exposures to ionizing radiation and toxic chemicals; and exposure to certain viruses including human immunodeficiency virus (HIV), Epstein-Barr virus, hepatitis-B and C, human papillomavirus, and human T-lymphotropic virus (NCI 1993). In the early 1980s, tobacco alone was estimated to be responsible for as many as 30% of all cancer cases (Doll and Peto 1981). In 1995, tobacco use was estimated to be responsible for 87% of lung cancers in the US (ACS 1995) (the leading type of cancer death in both sexes), and tobacco use also causes mouth, larynx, pharynx, esophagus, pancreas, cervix, kidney, and bladder cancers. On the other end of the scale, viruses and occupational exposures to toxic chemicals are each thought to account for about 5% of cancer deaths (NCI 1993). Environmental exposures, including contamination of air, water, and food are believed to account for a relatively small portion of cancer deaths (probably about 2 to 5%) (Doll and Peto 1981).

Although the risk of developing cancer generally increases with age, childhood cancers are of concern. One reason for this is that children are more sensitive to toxic substances and environmental exposures than adults (Bearer 1995). Children experience different and sometimes higher exposures than adults because they breathe air from lower zones where there are heavier gases and particles; they have a different metabolic rate, causing oxygen consumption and rates of absorption of nutrients and contaminants to be greater; they consume more food, and thus more contaminants, per unit of body weight; they consume more dairy products and produce, and the contaminants associated with these foods; young children are more likely than adults to put inedible items, such as dirt and paint, in their mouths; and infants have more absorptive stomachs and skin and less effective kidneys than adults. In addition, children are more susceptible than adults to exposures simply because they are growing and their cells are multiplying rapidly.

Because any cancer cases resulting from exposure to radioactive and hazardous waste from the WIPP would be superimposed on the much larger number of cancers caused by exposure to other carcinogens and the lifestyle factors described above, it may be difficult to determine whether the WIPP is contributing to cancer risk in the surrounding counties. Two ways to measure cancer occurrence in a community are to monitor counts of cancer cases and to monitor cancer incidence rates. Cancer incidence rates are the number of newly diagnosed cases of cancer occurring in a population over a period of time, divided by the number of people at risk for a particular cancer or cancers (Hennekens and Buring 1987). Cancer incidence rates are often the preferred method to monitor cancer in a community because they allow the comparison of cancer occurrence among populations of different sizes and may be adjusted to account for different age distributions. To investigate trends in cancer incidence rates after waste is placed in the WIPP, it is crucial to understand the history of incidence rates in the region surrounding the facility, both geographically and temporally.

Potentially Impacted Population

The people who live and/or work in Eddy and Lea counties are at the greatest risk of exposure in the event of release of radioactive and hazardous materials from the WIPP. The area surrounding the WIPP is rural, with approximately 36 people living within ten miles of the WIPP facility at the time of this study (Westinghouse 1995). Communities in Eddy and Lea counties include Carlsbad, Artesia, Hope, Jal, Eunice, Hobbs, Loving, Malaga, and Lovington. According to unpublished New Mexico Tumor Registry (NMTR) population estimates derived from US Bureau of Census figures (1990), Eddy County had a 1994 population of 52,789 people (including 31,759 non-Hispanic whites (i.e., Anglos) and 19,429 Hispanics), and Lea County had a 1994 population of 57,110 people (including 34,897 non-Hispanic whites and 18,887 Hispanics). All other races and ethnicities in 1994 comprised only about 2.5% of the population in Eddy County and 5.5% in Lea County. In Bureau of Census surveys, individuals identify their own race and ethnicity, and are asked whether they are of Hispanic origin.

At the time of this study, the WIPP employed about 1,000 people from surrounding communities (DOE 1996). Major industries in Eddy and Lea counties include oil and natural gas production and potash mining. Eddy County is one of the world's largest potash producers and one of New Mexico's largest oil and natural gas producers, and Lea County is New Mexico's largest oil and natural gas producer (BBER 1995). For the past two decades, population trends appear to have followed trends in the oil, natural gas, and potash industries in these counties. In general, in the 1970s, trends in industry and population fluctuated, with some overall increase. In the decade between 1980 and 1990, trends in industry and population rose to peak levels by about 1983, and then followed a fluctuating decline to the end of the decade. Since 1990, these trends have shown a slight increase. Although the number of people in the labor force remained fairly steady between 1980 and 1990, the number of people employed in mining decreased by 35.3% in Eddy County and by 31.8% in Lea County (BBER 1995). Lea County also experienced decreases in the number of people employed in agriculture; construction; manufacturing; transportation, communications, and public utilities; and finance, insurance, and real estate. The unemployment rate increased from 5.0 to 7.6 in Eddy County and from 2.8 to 7.2 in Lea County in this period. Possibly due to these economic factors, both counties experienced greater out-migration in the late 1980s than in-migration. In Lea County, natural population growth (births minus deaths) could not compensate for this out-migration, and the total population dropped down to the 1980 level.

Community Concerns

While there are some benefits, such as increased employment opportunities, of living near DOE facilities and nuclear power plants, residents in these communities often have a variety of associated concerns. The public may be worried about social issues, such as the stigma of living near a nuclear or hazardous waste facility, and economic issues, such as falling property values if a community is perceived as contaminated or unsafe (Guidotti and Jacobs 1993). In addition, concerns are voiced about the potential for adverse health effects from the daily operation of nuclear power plants and DOE facilities, as well as from accidents such as the radioactive emissions at the Three Mile Island nuclear plant in 1979 (Hatch et al. 1990; Jablon et al. 1990), and from the release of contaminants into the environment from accidents and improper disposal of waste at DOE facilities (OTA 1991).

These concerns are supported by a 1991 report by the Congress of the United States’ Office of Technology Assessment (OTA) which found that the DOE had a poor environmental record. At almost every facility in the DOE weapons manufacturing network, soil, air, and water are contaminated with both radioactive waste and hazardous chemical waste. In addition, the OTA found that issues have not been sufficiently investigated regarding the health impacts of this contamination. Thus, the public's concerns about the potential adverse health effects of contamination are difficult to alleviate because they cannot be substantiated or disproved. In its report, the OTA concluded that the DOE cannot have credibility with the public until, among other things, efforts are made to allow for independent oversight of public health and environmental safety issues, information about these issues is made readily accessible to the public, and the public is included in decision-making.