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Recent epidemiological studies have suggested an increased risk of non-Hodgkin lymphoma (NHL) from carbamate insecticide use among farmers. To further explore the possible relationships, we conducted a pooled analysis of three population-based case-control studies conducted in four midwestern states in the United States. A total of 985 white male subjects and 2895 control subjects were included in this analysis. Unconditional logistic regression was used to estimate the association and control for confounding. Compared with nonfarmers, farmers who had ever used carbamate pesticides had a 30% to 50% increased risk of NHL, whereas farmers without carbamate pesticide use showed no increased risk. Analyses for individual carbamate pesticides found a more consistent association with Sevin but not carbofuran, butylate, or S-ethyl dipropylthiocarbamate plus protectant. Among farmers using Sevin, the risk of NHL was limited to those who personally handled the product, those who first used the product for > or = 20 years before their disease diagnosis, and those who used the product for a longer period. These associations persisted after adjusting for other major classes of pesticides. These results suggest an increased risk of NHL associated with carbamate pesticide use, particularly Sevin. Further investigation of the association is warranted.

Purpose: The purpose of this study was to evaluate the role of physical activity in the development of non-Hodgkin's lymphoma (NHL)., Methods: Incident NHL cases and population-based controls were identified from three case-control studies conducted in four midwestern states: Iowa, Kansas, Minnesota, and Nebraska. A total of 1177 cases (993 men, 184 women) and 3625 controls (2918 men, 707 women) were interviewed. Usual occupation (all states) and lifetime occupational histories (Iowa and Minnesota only), obtained from interviews, were classified for energy expenditure (EE) and sitting time. Odds ratios (OR) and 95% confidence intervals were calculated comparing moderate and high activity levels with sedentary levels., Results: There was no evidence of an association between NHL and occupational physical activity measured either by EE or sitting time. Among men, the OR associated with usual occupation moderate and high EE were 1.1 and 1.0, respectively. For sitting time, the OR were also 1.1 and 1.0 for moderate and high activity, respectively. Among women, slight nonsignificant elevations in risk of NHL were observed among the high energy level and high activity sitting categories. The trends were not significant. There was no evidence of confounding or effect modification by vital status, hair dye use, or solvent exposure. Among subjects with lifetime occupational histories, there were no significant increases or trends for cumulative or average EE or sitting time. There was no association between occupational physical activity and NHL., Conclusion: Research on nonoccupational physical activity, which in the U.S. is likely the more important component of daily activity than occupational activity, may still be warranted given the laboratory evidence linking physical activity and immune function, an important factor in the etiology of NHL.

We conducted a study of occupation and mortality from reproductive cancers among women, based on death certificates from 24 US states for the period 1984-1993. There were 9,523 cervical cancer deaths, 12,335 endometrial cancer deaths, and 25,212 ovarian cancer deaths. Usual occupation and industry, which were obtained from death certificates, were coded using the 1980 Bureau of Census classification system. Mortality odds ratios (MORs) and 95% confidence intervals (CIs) were calculated, using all non-cancer deaths as the referent disease category. In general, jobs involving professional or administrative occupations were related to increased risk of mortality from endometrial and ovarian cancer, while cervical cancer mortality was increased among women employed in manufacturing, service, farm work, and health care technician and aide occupations. Associations with some occupations involving exposure to chemicals and metals, such as the associations between cervical cancer and employment in printing, typesetting, and machine operating occupations, deserve further attention. Similarly, further investigations should be made into the excess of ovarian cancer observed in several occupations in health care, an industry that has numerous hazardous exposures, including radiation, chemotherapeutic drugs, and viruses. The study results reflect, in part, socioeconomic factors and reproductive patterns but may also indicate a possible etiologic role for occupational chemical exposures.

In response to reports linking non-Hodgkin's lymphoma (NHL) and the herbicide 2,4-dichlorophenoxyacetic acid, a retrospective cohort mortality study of 32,600 employees of a lawn care company was conducted. The cohort was generally young with short-duration employment and follow-up. In comparison to the US population, the cohort had significantly decreased mortality from all causes of death combined (307 deaths), arteriosclerotic heart disease, and accidents. There were 45 cancer deaths (59.6 expected, standardized mortality ratio [SMR] = 0.76, 95% confidence interval [CI] = 0.55, 1.01). Bladder cancer mortality was significantly increased, but two of the three observed deaths had no direct occupational contact with pesticides. There were four deaths due to NHL (SMR = 1.14, CI = 0.31, 2.91); three were male lawn applicators (SMR = 1.63, CI = 0.33, 4.77), with two of the applicators employed for three or more years (SMR = 7.11, CI = 1.78, 28.42). No other cause of death was significantly elevated among lawn applicators as a group or among those employed for three or more years. Although based on very small numbers and perhaps due to chance, the NHL excess is consistent with several earlier studies.

The increasing incidence of non-Hodgkin's lymphoma (NHL) in the United States is only partially explained by known risk factors. Nitrate is a contaminant of drinking water in many rural areas. We evaluated its association with NHL after accounting for dietary nitrate intake. For 156 cases and 527 controls who used Nebraska community supplies, average nitrate exposure was estimated from 1947 through 1979. Longterm consumption of community water with average nitrate levels in the highest quartile (> or = 4 mg per liter nitrate-nitrogen) was positively associated with risk [odds ratio (OR) = 2.0; 95% confidence interval (CI) = 1.1-3.6]. Dietary nitrate, which came mainly from vegetables, was not associated with NHL risk, after adjusting for vitamin C and carotene intakes. Persons with a lower intake of vitamin C were at slightly higher risk of developing NHL than persons whose daily intake was > or = 130 mg, for all levels of intake of drinking water nitrate; our findings were similar for the combined effect of water nitrate and carotene intake. Nitrate levels in private wells were measured at the time of the interview for 51 cases and 150 controls but were not associated with the risk of NHL after adjusting for pesticide use on the farm. These findings indicate that longterm exposure to elevated nitrate levels in drinking water may contribute to the risk of NHL.

Epidemiologic studies of farmers have linked pesticides with certain cancers. Information on exposures from many of these studies was obtained by interview of farmers or their next-of-kin. The reliability and validity of data on pesticide use obtained by recall, often years after the event, have been questioned. Pesticide use, however, is an integral component in most agricultural operations, and the farmers' knowledge and recall of chemicals used may be better than for many other occupations. Contrary to general belief, many farmers typically use only a few pesticides during their lifetimes and make only a few applications per year. Data from U.S. Department of Agriculture surveys indicate that herbicides are applied to wheat, corn, soybeans, and cotton and that application of insecticides to corn averages two or fewer times per year. In epidemiologic studies at the National Cancer Institute, the proportion of farmers ever reporting lifetime use of five or more different chemicals was 7% for insecticides and 20% for herbicides. Surrogate respondents have often been used in epidemiologic studies of cancer; they are able to recall pesticide use with less detail than the farmers themselves. The pesticides reported by surrogates were the same as reported by subjects themselves, but with less frequency. Comparison of reporting by cases and controls provided no evidence of case-response (differential) bias; thus, inaccurate recall of pesticide use by subjects or surrogates would tend to diminish risk estimates and dilute exposure-response gradients.