Illness Indicators in Lompoc, California: An Evaluation of Available Data - June 1998

EXECUTIVE SUMMARY

An evaluation of available health data for Lompoc, California, was performed in response to a request from the California Department of Pesticide Regulation to "evaluate which illnesses in the Lompoc area are occurring at a higher rate than would normally be expected." This request to the Office of Environmental Health Hazard Assessment (OEHHA) was prompted by concerns expressed by some members of the community that Lompoc had an unhealthy environment brought about, in the residents’ perception, by use of pesticides in agricultural areas located close to residential areas. Some Lompoc residents have complained of a broad spectrum of health problems, including (among many others) asthma, bronchitis, otitis (ear infections), and several types of cancers, as well as a wide range of non-specific symptoms, such as nausea, headache, and lethargy. In addition, some residents reported that infants and children were sick more often than adults, and females more often than males.

The purpose of this evaluation was to determine if certain illnesses were elevated in Lompoc compared to other areas in California. Illnesses were examined that predominated in the complaints received from Lompoc residents. Although this evaluation was not intended to be a comprehensive evaluation of the health status of Lompoc residents, it was a first step in verifying the health concerns raised by residents and in defining which illnesses may need further study. Moreover, the results of this evaluation would provide direction for future studies designed to examine causality since that was not the intent of this evaluation.

This evaluation was based on readily available sources of health data. Accordingly, several county- or state-maintained databases were identified from which data were obtained for analysis. These data include cancer incidence data for 1988 to 1995 from the California Cancer Registry (CCR); birth defects data for 1987 to 1989 from the California Birth Defects Monitoring Program (CBDMP); information on live births for 1988 to 1994 from the California Department of Health Services (DHS); and hospital discharge data for 1991 to 1994 from the Office of Statewide Health Planning and Development (OSHPD).

Of these databases, OEHHA found that the cancer incidence and hospital discharge data were most relevant for evaluating the health complaints of the Lompoc residents. Incidence rates of lung and bronchus cancers were significantly elevated in Lompoc compared to expected numbers based on regional incidence rates. This elevation was about 37% above the expected incidence and was statistically significant at the 99% level. The incidence rates for other cancers (i.e., stomach, liver, breast, brain and other central nervous system, thyroid, female genital, male genital, kidney, Hodgkin’s disease, non-Hodgkin’s lymphoma, multiple myeloma, and leukemia) were not significantly elevated.

The hospital discharge data analysis showed Lompoc to have elevated proportions of hospital discharges for bronchitis, asthma, and perinatal respiratory disease relative to the total of all non-birth or non-birth-related hospital discharges. This elevation showed up when Lompoc was compared to Santa Barbara County excluding Lompoc, Ventura, San Luis Obispo, Mendocino, or Humboldt plus Del Norte counties. Bronchitis and asthma discharges were elevated approximately equally when the two discharge categories were analyzed separately by International Classification of Diseases (ICD-9) codes (for bronchitis, odds ratio (OR)=1.69, i.e., 69% increase, and for asthma OR=1.58, i.e., 58% increase). Bronchitis discharges were significantly elevated in the youngest and oldest age groups (<5 and ³ 60 years old), while asthma discharges were significantly elevated only among adults older than 25 years. There was no difference between seasonal variation of Lompoc and seasonal variation of the comparison counties when bronchitis or asthma discharges were compared by admission quarter.

The excess proportion of hospital discharges for respiratory illness in Lompoc was not explained by age (although age was a partially confounding factor), sex, race/ethnicity, admission quarter (a measure of seasonal variation), or admission year, although the excess was greater in some years than others. The pattern of elevated respiratory discharges, which was demonstrated using multiple county comparisons, essentially was replicated in the individual county comparisons. A discriminant function analysis corroborated these findings by showing that residence in Lompoc was associated with elevated bronchitis and asthma discharges independent of age, race/ethnicity, sex, and admission quarter. An additional analysis comparing several nearby towns or towns located farther away but surrounded by agriculture to the five-county control area showed that Lompoc appears unique in having elevated proportions of hospital discharges for bronchitis, asthma, and perinatal respiratory disease.

Rates of seven common birth defects were not significantly increased in Lompoc nor were there any patterns among cases to suggest a common underlying cause. A review of the birth profiles indicated that more than 90% of babies born to mothers in Lompoc had normal birthweights and most mothers received prenatal care.

The four databases analyzed were considered the most appropriate for providing health-related and reliable information for the objectives at hand. Nevertheless, they are subject to many limitations. For cancer incidence, data on risk factors such as diet, smoking habits, or lifestyle, are not collected by the CCR; however, such factors may have a profound influence on the incidence and types of cancers observed in a population. Approximately 85% of lung cancers can be attributed to tobacco use; therefore information on smoking habits is critical to determining potential causes for the increased incidence of lung cancer in Lompoc.

Birth defects data specific for Lompoc (Zip Codes 93436 and 93438) were only available for 1987 to 1989, the years in which Santa Barbara County was included in the CBDMP. The conclusions reached by the CBDMP are based on a relatively small number of births (2,492) and have limited statistical power. Additionally, any changes in environmental conditions or birth defects patterns that might have occurred since 1989 cannot readily be analyzed due to lack of available data. When evaluated in conjunction with birth defects data, the birth profile data may offer additional insight into possible causes of birth anomalies (e.g., risk factors related to maternal age), although they do not provide definitive cause and effect relationships. However, analysis of these data did not reveal any useful information pertaining to the symptoms or illness complaints described to OEHHA staff by residents.

It is possible that the results obtained in the hospital discharge data analysis might partially be due to a statistical artifact; that is, some statistically significant findings can emerge by chance alone. OEHHA tried to address this possibility through the use of multiple statistical methods and reference groups, as well as multiple comparison areas. Since the same basic discharge patterns were identified using different analytical methods, we do not believe that false positive results are a likely explanation of our findings. Calculating incidence rates of hospital discharges would be a more direct approach to addressing the issue of increased illness in Lompoc. However, we were not able to obtain reliable population estimates for Lompoc for the years following the 1990 Census, and using the estimates we did obtain would have introduced an unknown source of error into the rate calculations, resulting in low confidence in the incidence rate estimates. Other aspects of the data analysis that we were unable to address with the available OSHPD database include differences in admission criteria applied by local physicians or insurance carriers, multiple admissions of patients for the same diagnosis, personal factors (e.g., occupational history, potential environmental exposures, dietary habits, tobacco use), and specific location of residence. Moreover, hospital admissions most likely cover more severe illnesses, whereas the majority of complaints received from residents were related to respiratory symptoms and other minor illnesses that would not require hospitalization. This analysis, therefore, could not fully address the issues relating to the health status of Lompoc residents.

Considering the limitations of the overall database available for evaluation, and notwithstanding the limitations of the hospital discharge data analysis itself, we found that the hospital discharge data analysis most directly addressed the objective of this evaluation- to determine if certain illnesses were elevated in Lompoc compared to other areas. The analysis was based upon a large sample size (647,290 hospital discharges), covered a four-year period (1991 through 1994), and used five counties as comparisons. Several methods of analysis were used, which provided similar results, increasing confidence in the interpretation of the data. The analysis focused upon physician diagnoses of illnesses, and the hospital discharge database is subject to extensive quality assurance, as it is maintained as an official record by the State of California.

This analysis shows elevated hospital discharges for respiratory illnesses and increased incidence rates for lung and bronchus cancers in Lompoc relative to comparison areas. Elevated respiratory illnesses are consistent with some of the community concerns that prompted this evaluation; however, this analysis did not address whether there were any specific cause(s) for the elevated illnesses. The findings of this report may be useful in determining the direction and scope of any future investigation, such as focusing on disease incidence, a wider range of illness severity (symptoms and mortality), and obtaining personal histories of residents, including occupational and other pertinent exposures, and tobacco use. Environmental correlates of residence in Lompoc, such as meteorological conditions, seasonal differences, and ambient environmental contaminants, should be investigated.

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