Use of a crop and job specific exposure matrix for estimating cumulative exposure to triazine herbicides among females in a case-control study in the Central Valley of California.

AIMS: To determine if a job exposure matrix (JEM) could be developed using the California Department of Pesticide Regulation Pesticide Usage Database in conjunction with crop, time, and county specific self reported work history and to determine if this was a feasible method to obtain exposure estimates to triazine herbicides. METHODS: Agricultural work histories were gathered from women enrolled in a population based case-control study of ovarian cancer cases and random controls. The work histories were used in conjunction with the database to construct job exposure matrices which took into account weightings for job type, work location, and crop. RESULTS: Cumulative exposure estimates were determined for 98 study subjects. Mean exposure estimates were similar for cases and controls. The exposure estimates were robust and insensitive to varying job weight assumptions. The estimates from the original weights were highly correlated with those constructed using the conservative and maximum weights. Estimates from all three schemes produced similar multivariate age adjusted odds ratios comparing cases and controls. There was a high degree of agreement in categorised quartiles of exposure between the original and conservative, and original and maximum weights. CONCLUSIONS: The exposure estimate from the JEM provides a ranking of exposure within the study population that can be utilised as an "exposure score" with which to compare groups. Although it is not an absolute exposure measurement, it does offer a substantial advance over dichotomous categories based on self report of herbicide use, particularly when subjects are unlikely to recall specific names and dates of use of herbicides.

Development of a life events/icon calendar questionnaire to ascertain occupational histories and other characteristics of migrant farmworkers.

BACKGROUND: Specialized methods are necessary to collect data from migrant farmworkers for epidemiologic research. METHODS: We developed a questionnaire that collected lifetime occupational histories and other lifestyle risk factors via a life events/icon calendar, and administered the questionnaire to a convenience sample of 162 migrant farmworkers in nine areas of the U.S. RESULTS: The average duration of the interviews was about 1 h 30 min, with an average of 45 min for the work history section. The occupational histories covered a median of 27.6 years per person for men and 20.8 years per person for women. The median number of years spent in farm jobs was 11.3 for men and 5.8 for women. The median number of farm jobs (crop/task combination) per person was 59 among men and 27 among women. Many farmworkers performed the same crop/task combinations at multiple times throughout their lives, yielding a median of 13 unique farm jobs and 8 unique crops among men and 7 jobs and 5 crops among women. CONCLUSIONS: The project demonstrated that it is feasible to collect detailed work histories and other risk factor data from farmworkers, documented the complexity of work histories encountered among farmworkers, and yielded recommendations for refining a questionnaire that will facilitate future epidemiologic research on farmworkers.

Organophosphate pesticide residues in urine of farmworkers and their children in Fresno County, California.

BACKGROUND: Childhood cancer, notably leukemia, brain cancer, non-Hodgkin's lymphoma, soft tissue sarcoma, and Hodgkin's disease, has been associated with pesticide exposure, often with greater relative risks than among exposed adults, suggesting greater susceptibility in children. These differences in risk may be due to developmental factors or differences in pesticide exposure. METHODS: A feasibility study was conducted to determine levels of pesticide metabolites in urine of adults (n = 18) and children (n = 9) in Fresno County, California, an intensely agricultural county in the Central San Joaquin Valley. Spot urine samples were obtained and analyzed for six metabolites of organophosphate (OP) pesticides using gas chromatography with flame photometric detection methods. The metabolites of OP pesticides included DMP, DEP, DMTP, DMDTP, DETP, and DEDTP. RESULTS: Levels were generally low for both adults and children for most metabolites tested. Frequencies of detection ranged from 0 to 37%, with mean levels ranging from non-detectable to 13.22 ppb. However, levels of several metabolites were higher in children than in adults. The most frequently detected metabolite, DMP, was found among 44% of the children and 33% of the adults. DMTP was detected among 33% of the children and 28% of the adults. CONCLUSIONS: These results are difficult to interpret given the sampling variation associated with the small sample size. Nevertheless, because OP pesticides have been associated with increased cancer risk in animal and human studies, these results indicate a need to closely monitor children's exposure to environmental chemicals.

Cancer incidence in the United Farmworkers of America (UFW), 1987-1997.

BACKGROUND: The purpose of this study was to evaluate cancer incidence in the membership a largely Hispanic farmworker labor union in California, the United Farmworkers of America (UFW) and to examine cancer-site specific distributions as well as histology and stage of cancer at diagnosis in this group. METHODS: An electronic record linkage was conducted between a membership roster of the UFW and the database of the California Cancer Registry, the population-based cancer registry in California for the years 1987-1997. Based upon the results of the linkage, morbidity odds ratios were calculated using the distribution of cancer in the California Hispanic population as the reference to determine if risk of specific cancers was higher or lower in the UFW. Time since first joining the union was evaluated, as was the proportional distribution of histologic subtypes and stage at diagnosis, again comparing the experience of the UFW membership to the California Hispanic population. RESULTS: Several types of cancer were elevated in the UFW membership in comparison to the California Hispanic population. Morbidity odds ratios and 95% confidence limits were elevated for leukemia (O.R. = 1.59: 95% C.I. = 1.07-2.37), stomach cancer (O.R. = 1.69: 95% C.I. = 1.24-2.27), uterine cervix cancer (O.R. = 1.63: 95% C.I. = 1.11-2.44) and uterine corpus cancer (O.R. = 1.68: 95% C.I. = 1.05-2.67). Brain cancer was also elevated although not significantly so (O.R. = 1.57: 95% C.I. = 0.96-2.53). CONCLUSIONS: Risk of leukemia, stomach, cervix and uterine cancers was elevated in California farmworkers. The histologic distribution of leukemia and brain cancers within the UFW membership did not differ from the distribution in the general California population although small numbers of cancers in the UFW hindered interpretation of these results. Members of the UFW experienced later stage of disease at diagnosis in comparison to California Hispanics for most major cancer sites but not for breast cancer.

The influence of urbanization, age, ethnicity, and income on the early diagnosis of breast carcinoma: opportunity for screening improvement.

BACKGROUND: Because most risk factors for breast carcinoma are not readily amenable to primary prevention, and early diagnosis is a powerful prognostic determinant, screening for the disease is crucial. Consequently, assessment of the progress and comprehensiveness of screening and other breast carcinoma early detection activities is important. The relative frequency of early diagnosis may provide a useful indicator of such activities. Nationwide, time trends in the early diagnosis of breast carcinoma have been improving for decades, but not all population subgroups may have benefited equally. METHODS: Using 1994-1997 data from the California Cancer Registry (CCR), a review of diagnostic patterns of in situ and local stage breast carcinoma was undertaken. For analytic purposes, the CCR includes 10 regional registries and 36 county reporting groups. Three early diagnostic measures were designated, including in situ breast carcinoma with tumor size < 10 mm in greatest dimension, in situ breast carcinoma, and localized breast carcinoma with tumor size < 21 mm in greatest dimension. These are referred to hereinafter as early diagnosis breast carcinomas. RESULTS: The percentage of early diagnosis breast carcinomas differed markedly by age, ethnicity, diagnosis year, and county of residence. Lower percentages of early diagnosis breast carcinomas were diagnosed in older women age >/= 85 years. Hispanic women were diagnosed with lower levels of in situ breast carcinoma. Hispanic and black women were diagnosed with less localized breast tumors of small size. There was an increase in the percentage of early diagnosis breast carcinomas over the 4-year observation period. Lower percentages of early diagnosis breast carcinomas were reported for the nonurban county/county groups, which were characterized by greater distances, lower population density, and lower household incomes. CONCLUSIONS: The authors conclude that elderly women, Hispanic and black women, and women who reside in nonurban areas should be targeted as high-priority subpopulations for mammographic screening.

Correlation analysis of pesticide use data and cancer incidence rates in California counties.

California, the leading agricultural state in the United States, has maintained a population-based cancer registry since 1988, and it also maintains a comprehensive, state-wide pesticide reporting system. Data on cancer incidence and pesticide use reporting are available, by county, for all 58 counties in California. Average annual age-adjusted cancer incidence rates (1988-1992), on a county-, sex-, and race/ethnicity-specific basis, were obtained from the California Cancer Registry (CCR), which maintains the population-based cancer registry throughout California. Pesticide use data (i.e., pounds of active ingredient applied annually in each county) were obtained from the California Department of Pesticide Regulation for 1993. Investigators used Pearson product-moment correlation coefficients (r) to correlate age-adjusted incidence rates for selected cancers with the use data for selected pesticides. For most sex- and race/ethnicity-specific groups, the correlation coefficients were very close to zero or negative in sign, indicating no correlation between pesticide use and cancer incidence. There were, however, several exceptions, particularly in Hispanic males for whom the following correlations were observed: leukemia and atrazine (r=.40), leukemia and 2,4-dichlorophenoxyacetic acid (r=.41), leukemia and captan (r=.46), atrazine and brain cancer (r=.54), and atrazine and testicular cancer (r=.41). For black males, we observed the following: atrazine and prostate cancer (r=.67) and Captan and prostate cancer (r=.49). In females, only a few of the correlations were elevated. Although most of the correlations examined in this analysis were not elevated, several of those in the Hispanic and black male populations were. These segments of the population have traditionally been employed as farm workers in California and have had the greatest potential for exposure to pesticides. This was an ecological study for which no data about exposure to pesticides at the individual level were available for analysis. In addition, no latency period was allowed between potential exposure and diagnosis with cancer. However, the results obtained in two minority groups who represented the majority of farm workers in the fields suggested that additional research studies, in which more rigorous study designs are used, should be conducted in those groups.

Cancer incidence in the Hmong of Central California, United States, 1987-94.

The Hmong are an ethnic minority in China, some of whom migrated to the mountainous areas of North Vietnam, Laos, and Thailand in the 19th and 20th centuries. Because of their support for the United States during the Vietnam war, many Laotian Hmong fled to Thailand and eventually were re-settled in the US after the end of that conflict. Approximately 100,000 Hmong currently live in the US, of whom about half reside in the Central Valley of California. The purpose of this study was to measure cancer incidence in this unique new immigrant population. Using the resources of the Cancer Registry of Central California (CRCC), a population-based cancer registry, cancer incidence in the Hmong was evaluated by calculating age-adjusted incidence rates as well as by calculating proportional incidence ratios. Compared with all races combined, elevated rates of cancer in the Hmong were observed for the following sites: nasopharynx, stomach, liver, pancreas, leukemia, and non-Hodgkin's lymphoma. Cervical cancer incidence overall was elevated, but more noteworthy, invasive cervix cancer rates were much higher than expected. Lower cancer rates were found for breast, prostate, and colorectal cancer. Hmong also experienced advanced stage and grade of disease at diagnosis for many cancer sites in addition to cervical cancer, which may be explained by cultural factors, including avoidance of Western medical care and low rates of participation in screening programs. This population should be followed closely and monitored for patterns of cancer incidence in the future since it provides a natural laboratory for studies of cancer etiology as this population gradually becomes acculturated to the Western lifestyle.

Estimated long-term ambient concentrations of PM10 and development of respiratory symptoms in a nonsmoking population.

Site- and season-specific regressions of particulates less than 10 mu in diameter (PM10) on total suspended particulates (TSPs) were formed throughout California during years when both were monitored. The regressions were then applied to monitored TSPs for the years 1973 to 1987, and indirect estimates of PM10 were formed. These estimates of PM10 were validated by interpolating them to other monitoring stations. The split-halves correlation between the estimated and monitored mean concentrations, obtained when both were first cumulated for a 2-y period, was .86. Indirect estimates of PM10 at monitoring stations were interpolated, by month, to zip code centroids of home and work location and were cumulated for a cohort of 3,914 California Seventh-day Adventist (SDA) nonsmokers. Multivariate analyses, adjusted for several covariates, showed statistically significant (p < .05), but small, positive associations between PM10 and development of (a) definite symptoms of overall airway obstructive disease, (b) chronic productive cough, and (c) increased severity of airway obstructive disease and asthma. The relative risk (RR) associated with 1,000 h/y (42 d) exposure to concentrations of PM10 that exceeded 100 micrograms/m3 for development of airway obstructive disease was 1.17 (95% confidence interval [CI]: 1.02, 1.33); for development of productive cough, the RR was 1.21 (CI 1.02, 1.44); and for development of asthma, the RR was 1.30 (CI, 0.97, 1.73). Stronger associations were observed for those who were exposed occupationally to dusts and fumes. The RR of developing airway obstructive disease as an adult for those who had airway obstructive disease as a child was 1.66 (CI 1.15, 2.33).

Cancer incidence among California Seventh-Day Adventists, 1976-1982.

Cancer incidence was monitored in a population of 34,000 Seventh-day Adventists in California. By religious belief, Adventists do not consume tobacco, alcohol, or pork and approximately one-half adhere to a lacto-ovovegetarian lifestyle. Only a small percentage are pure vegetarians. Comparisons of cancer-incidence rates in this population with an external reference population were completed by calculating standardized morbidity ratios (SMRs) for all cancer sites. Also, within the population, relative risks were calculated by using data obtained from a detailed lifestyle questionnaire that members of the study population completed. For all cancer sites combined in males, the SMR was lower in the Adventists (SMR = 0.73). The SMR was also lower in males for most individual cancer sites. However, prostate cancer risk was higher. For females, the all-cancer SMR was lower but not significantly so (SMR = 92). Most site-specific SMRs were lower, although not as much as the male SMRs. The SMR for endometrial cancer was significantly higher in female Adventists.

Chronic disease associated with long-term concentrations of nitrogen dioxide.

A prospective epidemiologic cohort study of 6,000 residentially stable and non-smoking Seventh-day Adventists (SDA) in California was conducted to evaluate long-term cumulative levels of ambient nitrogen dioxide (NO2) in association with several chronic diseases. These diseases included respiratory symptoms, cancer, myocardial infarction (MI), and all natural causes mortality. Cumulative ambient concentrations of NO2 were estimated for each study subject using monthly interpolations from fixed site monitoring stations and applying these estimates to the monthly residence and work place zip code histories of study participants. In addition, a personal NO2 exposure study on a randomly selected sample of 650 people in southern California was conducted to predict total personal NO2 exposure using household and lifestyle characteristics and ambient NO2 concentrations. It was found that good predictability could be obtained (correlation coefficient between predicted and observed values = 0.79) from a model predicting personal NO2. The resulting regression equations from the personal NO2 exposure study were applied to the epidemiologic study cohort to adjust ambient concentrations of NO2.

Long-term ambient concentrations of total suspended particulates, ozone, and sulfur dioxide and respiratory symptoms in a nonsmoking population.

Seventh-day Adventist nonsmokers, who, subsequent to 1966, had resided within 8 km (5 miles) of their 1977 residence (N = 3,914), completed the National Heart and Lung Institute (NHLI) respiratory symptoms questionnaire in 1977 and again in 1987. For each participant, cumulative ambient concentrations of total suspended particulates (TSP), ozone, and sulfur dioxide (SO2) in excess of several cutoff levels were estimated by month and by interpolating ambient concentrations from state air-monitoring stations to their residential and workplace zip codes for the month. Statistically significant relationships between ambient concentrations of TSP and ozone, but not SO2, were found with several respiratory disease outcomes. Multivariate analyses adjusted for past and passive smoking and occupational exposures. Results are discussed within the context of standards setting for TSP and ozone.

Chronic respiratory disease associated with long-term ambient concentrations of sulfates and other air pollutants.

Seventh-day Adventist (SDA) non-smokers who had resided since 1966 within five miles of their 1977 residence (n = 3914) completed a standardized respiratory symptoms questionnaire in 1977 and again in 1987. For each participant, cumulative ambient concentrations from 1977 to 1987 of suspended sulfates (SO4) in excess of several cutoffs as well as mean concentrations were estimated by interpolating monthly ambient concentration statistics from state air monitoring stations to the individual's residential and workplace zip codes. There were significant associations between ambient concentrations of suspended sulfates and development of new cases of asthma, but not new cases of overall airway obstructive disease (AOD) or chronic bronchitis. Comparison of previous analyses, in this population, of respiratory disease symptoms and total suspended particulates (TSP), ozone, and sulfur dioxide (SO2), and multipollutant analyses of these pollutants with SO4, indicated these results were not due to a surrogate relationship with other air pollutants. Development of definite symptoms of AOD and chronic bronchitis was most strongly related to TSP.

Allergy and cancer: organ site-specific results from the Adventist Health Study.

The relation between allergy and risk of cancer was evaluated in a cohort study of 34,198 Seventh-day Adventists in California. Information on prevalence of asthma, hay fever, and reactions to chemicals, medications, bee stings, and poison oak (or ivy) was obtained by questionnaire in 1976. The reported allergies must have been serious enough to require treatment by a physician. The cohort was then followed for 6 years (1977-1982). Both stratified analysis and Cox proportional hazards regression analyses were utilized to evaluate the relation of allergy to cancer after taking into account several potentially confounding variables. For all cancer sites combined in males, there was a 33% increased risk associated with reaction to medications. In contrast, among females, reaction to medications was associated with a 21% decrease in risk. Both results were statistically significant. Prostate and breast cancer risk were elevated in persons who reported any type of allergic history, as was risk of lymphatic or hematopoietic cancers and sarcoma. For each of these types of cancer, risk increased with increasing numbers of allergies. However, ovarian cancer risk was decreased in persons with any allergic history and increasing numbers of allergies was associated with decreasing risk of this form of cancer. These results suggest that the association between allergy and cancer is complex and depends on the specific allergy and the specific organ site under consideration.

Ambient air pollution and cancer in California Seventh-day Adventists.

Cancer incidence and mortality in a cohort of 6,000 Seventh-day Adventist nonsmokers who were residents of California were monitored for a 6-y period, and relationships with long-term ambient concentrations of total suspended particulates (TSPs) and ozone (O3) were studied. Ambient concentrations were expressed as mean concentrations and exceedance frequencies, which are the number of hours during which concentrations exceeded specified cutoffs (e.g., federal and California air quality standards). Risk of malignant neoplasms in females increased concurrently with exceedance frequencies for all TSP cutoffs, except the lowest, and these increased risks were highly statistically significant. An increased risk of respiratory cancers was associated with only one cutoff of O3, and this result was of borderline significance. These results are presented in the context of setting standards for these two air pollutants.

Long-term ambient concentrations of total suspended particulates and oxidants as related to incidence of chronic disease in California Seventh-Day Adventists.

Cancer incidence and mortality in a cohort of 6000 nonsmoking California Seventh-Day Adventists were monitored for a 6-year period, and relationships with long-term cumulative ambient air pollution were observed. Total suspended particulates (TSP) and ozone were measured in terms of numbers of hours in excess of several threshold levels corresponding to national standards as well as mean concentration. For all malignant neoplasms among females, risk increased with increasing exceedance frequencies of all thresholds of TSP except the lowest one, and those increased risks were highly statistically significant. For respiratory cancers, increased risk was associated with only one threshold of ozone, and this result was of borderline significance. Respiratory disease symptoms were assessed in 1977 and again in 1987 using the National Heart, Lung and Blood Institute respiratory symptoms questionnaire on a subcohort of 3914 individuals. Multivariate analyses which adjusted for past and passive smoking and occupational exposures indicated statistically significantly (p less than 0.05) elevated relative risks ranging up to 1.7 for incidence of asthma, definite symptoms of airway obstructive disease, and chronic bronchitis with TSP in excess of all thresholds except the lowest one but not for any thresholds of ozone. A trend association (p = 0.056) was noted between the threshold of 10 pphm ozone and incidence of asthma. These results are presented within the context of standards setting for these constituents of air pollution.

Bladder cancer in a low risk population: results from the Adventist Health Study.

A cohort study of bladder cancer was conducted in a population of California Seventh-day Adventists. Most Seventh-day Adventists use neither tobacco nor alcohol yet experience a large degree of variation in dietary habits. Therefore, diet and other lifestyle habits were evaluated in this unique population. In 1976, 34,198 non-Hispanic white Seventh-day Adventists in California completed a detailed lifestyle questionnaire which included a 51-item food frequency section. This cohort was then followed until the end of 1982 during which time all newly diagnosed malignancies were detected. In order to evaluate the relation between several variables hypothesized to be associated with altered bladder cancer risk, age-, sex-, and smoking-adjusted relative risks (incidence rate ratios) were calculated using the method of Mantel-Haenszel adopted for person-time data. Multivariate analyses were conducted using the Cox Proportional Hazards Regression model. Between the return of the questionnaire and the end of follow-up, there were 52 histologically confirmed bladder cancers detected in the cohort. Increasing age, male gender, and a history of cigarette smoking were all significantly associated with increased bladder cancer risk. In addition, residence in a rural area was associated with significantly increased risk (relative risk (RR) = 1.80) as was high consumption of meat, poultry, and fish (RR = 2.57).

History of cigarette smoking and risk of leukemia and myeloma: results from the Adventist health study.

The risks of leukemia and myeloma associated with cigarette smoking were evaluated in a cohort study of 34,000 Seventh-day Adventists. Although Seventh-day Adventists do not smoke by church proscription, many are adult converts who smoked cigarettes prior to their baptism into the church. In comparison with those who never smoked, ex-smokers experience a relative risk of 2.00 (95% confidence interval = 1.01-3.95) for leukemia and 3.01 (95% confidence interval = 1.13-8.05) for myeloma. Risks increased in a dose-response fashion with increasing numbers of cigarettes smoked daily for both leukemia (trend P = .009) and myeloma (trend P = .005). Also, the risks of both leukemia and myeloma increased with the total duration of cigarette smoking. The cigarette smoking-leukemia relationship was strongest for myeloid leukemia, for which ex-smokers experienced a relative risk of 2.24 (95% confidence interval = 0.91-5.53). These data lend support to the hypothesis that cigarette smoke may induce malignant degeneration in bone marrow and its products.

Chronic disease among Seventh-day Adventists, a low-risk group. Rationale, methodology, and description of the population.

The Adventist Health Study is a prospective cohort study of 34,198 non-Hispanic white Seventh-day Adventists (13,857 men; 20,341 women, age 25-100 years) followed for 6 years (1977-1982). Within this population, 55.2% were lacto-ovovegetarian (consumed meat, poultry, or fish less than one time per week with no restrictions as to egg or dairy product consumption) in 1976 and most abstained from alcohol, tobacco, and pork products. Baseline data included demographic variables, information on current and past dietary habits, exercise patterns, use of prescription drugs, use of alcohol and tobacco, measures of religiosity, occupation and residential histories, anthropometric data, and menstrual and reproductive histories. Nonfatal case ascertainment was completed through review of self-reported hospitalizations obtained from annual self-administered mailed questionnaires and through computerized record linkage with two California population-based tumor registries. Fatal case ascertainment was completed via record linkage with computerized California state death certificate files, the National Death Index, and individual follow-up. During the 6 years of follow-up, 52.8% of the 34,198 study subjects reported at least one hospitalization. A total of 20,702 medical charts were reviewed for cancer and cardiovascular disease incidence and 1406 incident cancer cases and 2716 deaths from all causes were identified after baseline data collection.