A case-control study of occupational and environmental risk factors for Parkinson's disease in the Emilia-Romagna region of Italy

A questionnaire-based case-control study was carried out on 86 patients with neurologist-confirmed idiopathic Parkinson's disease (PD) and 86 controls similar in sex and age. The control group was recruited in outpatient specialist centers of the same University Hospital (glaucoma, psoriasis vulgaris, essential arterial hypertension and renal diseases). Exposure was defined as occupational or residential contact with a given factor for at least 10 consecutive years prior to the onset of PD. Smoking habits were defined by exclusion of those subjects who never smoked. The following risk factors were identified: cranial trauma (OR: 2.88; 95% CI: 0.98-8.49), well water use (OR: 2.78; 95% CI: 1.46-5.28) and occupational exposure to industrial chemicals (OR: 2.13; 95% CI: 1.16-3.91). Among industrial chemicals, only organic solvents were identified as significant risk factors for PD (O.R. : 2.78, 95% C.I. : 1.23-6.26). Whereas no exposure to neurotoxic metals occurred among controls, making the assessment of the O.R. impossible, exposure pesticides and herbicides was similar in the two groups (O.R. : 1.15; 95% C. : 0.56-2-36). Smoking habits was negatively associated with PD (OR: 0.41; 95% CI: 0.22-0.75), confirming the "protective" role of tobacco smoking suggested by many studies. As a whole, these results support the role of environmental factors in the etiology of PD.     

Sex and reproduction in the nematode C. elegans]

BACKGROUND: An exploratory, case-control study was used to investigate a new hypothesis about suicide among farm operators. This hypothesis suggested a biologically plausible link between exposures to certain pesticides and the occurrence of suicide among farm operators. These analyses were based on data from the Canadian Farm Operator Cohort. METHODS: Canadian male farm operators who committed suicide between 1971-1987 (n = 1,457) were compared with a frequency matched (by age and province) sample of control farm operators (n = 11,656) who were alive at the time of death of individual cases. Comparisons focused on past exposures to pesticides reported to the 1971 Canada Census of Agriculture. RESULTS: Multivariate logistic regression analyses indicated no associations between suicide and (1) acres sprayed with herbicides, (2) acres sprayed with insecticides, and (3) the costs of agricultural chemicals purchased; after controlling for important covariates. There was, however, a suggestive increase in risk for suicide associated with herbicide and insecticide spraying among a subgroup of farm operators who were most likely to be directly exposed to pesticides: OR = 1.71 (95% CI = 1.08-2.71) for 1-48 vs. 0 acres sprayed. Additional risk factors that were identified included seasonal vs. year-round farm work (OR = 1.68; 95% CI = 1.15-2.46); and high levels of paid labor on the farm (e.g., OR = 1.61; 95% CI = 1.24-2.10, for > 13 vs. 0 weeks per year). Factors that were protective included marriage (odds ratio (OR) = 0.69; 95% confidence interval (CI) = 0.58-0.81), having more than one person resident in the farm house (e.g., two vs. one person; OR = 0.62; 95% CI = 0.42-0.92); and higher levels of education (e.g., postsecondary vs. primary; OR = 0.40; 95% CI = 0.17-0.96). CONCLUSIONS: This study does not provide strong support for the main hypothesis under study, that exposure to pesticides is an important risk factor for suicide among farmers. Although secondary to the main hypothesis, a number of other risk factors for suicide were suggested. These have implications for the future study and targeting of suicide prevention programs in rural Canada.     

The N-terminus of Nef from HIV-1/SIV associates with a protein complex containing Lck and a serine kinase

A multi-center case-referent study was conducted on the relation between paternal occupational exposure and spina bifida in offspring. Cases were born between 1980 and 1992 in The Netherlands. Referents were recruited from hospitals and from the general population. Postal questionnaires were used to gather information on occupation and potential confounders. Through job-specific telephone interviews with 122 case fathers and 411 referent fathers, detailed exposure information was collected on specific tasks, the use of chemical or physical agents, frequency of exposure, and use of protective equipment. The study yielded statistically significant associations between spina bifida and low exposure to welding fumes (OR = 1.6, 95% CI: 1.0-2.6) and low exposure to UV radiation during welding (OR = 2.6, 95% CI: 1.2-5.6), and suggestive findings of an association between spina bifida and moderate or high exposure to cleaning agents, moderate or high pesticide exposure (OR = 1.7, 95% CI: 0.7-4.0), and stainless steel dust (OR = 2.0, 95% CI: 0.8-5.2). No associations were identified for other paternal occupational exposures, such as organic solvents.     

Optimization of energy-dependent processes in mitochondria from rat liver and brain after inhalation of negative air ions

BACKGROUND: Bone cancers in children are serious and highly fatal conditions, yet relatively little is known about their causes or methods of prevention. METHODS: The relationship between parental occupation and bone cancer in offspring was explored in a case-control study. Cases were identified from the Ontario Cancer Registry; population-based controls were matched on sex and age. Data were collected from their parents through the use of a mailed self-administered questionnaire. RESULTS: The odds ratio estimates (OR) for bone cancer were elevated for fathers in the social sciences (OR = 2.5, 95% confidence interval [CI]: 0.7-8.4). Risk of Ewing's sarcoma was significantly high among children with fathers in social sciences (OR = 6.2, 95% CI: 1.6-24.5) and mothers in teaching (OR = 3.1, 95% CI: 1.1-8.7) or farming (OR = 7.8, 95% CI: 1.9-31.7). Osteosarcoma risk was increased for fathers in farming (OR = 2.1, 95% CI: 0.8-5.7), and mothers in managerial and administrative work (OR = 2.3, 95% CI: 0.6-8.1), and product fabricating, assembling, and repairing (OR = 2.0, 95% CI: 0.6-7.2). CONCLUSIONS: Certain methodological problems plague studies of bone cancer in children (e.g. small studies, low statistical power, analysis of multiple occupational categories, difficulty in identifying specific carcinogenic agents). These associations require further investigation, especially as elevated risks have been reported previously for agricultural occupations.     

Occupational exposures and amyotrophic lateral sclerosis. A population-based case-control study

This population-based case-control study was conducted in three countries in western Washington State to evaluate associations between workplace exposures and the risk of amyotrophic lateral sclerosis (ALS). Cases (n = 174) were all newly diagnosed with ALS by neurologists during 1990-1994, and controls (n = 348), who were matched according to age (+/-5 years) and sex, were identified via random-digit dialing or Medicare enrollment files. Four industrial hygienists blindly assessed detailed lifetime job histories for exposures to metals, solvents, and agricultural chemicals. Case-control comparisons were made for jobs held between 15 years of age and 10 years prior to the cases' dates of diagnosis. After adjustment for age and education, ever exposure to agricultural chemicals was associated with ALS (odds ratio (OR) = 2.0, 95% confidence interval (CI) 1.1-3.5); this association was observed separately in men (OR = 2.4, 95% CI 1.2-4.8) but not in women (OR = 0.9, 95% CI 0.2-3.8). Among men, the odds ratio for low exposure to agricultural chemicals (below the median level for exposed controls) relative to no exposure was 1.5 (95% CI 0.4-5.3), and for high exposure, it was 2.8 (95% CI 1.3-6.1) (p for trend = 0.03). Similar analyses based on the panel's assessment of exposures to metals and solvents showed no associations. These findings suggest an association between ALS and agricultural chemicals in men.     

Diet and Parkinson's disease. II: A possible role for the past intake of specific nutrients. Results from a self-administered food-frequency questionnaire in a case-control study

In a case-control study, we compared the past dietary habits of 342 Parkinson's disease (PD) patients recruited from nine German clinics with those of 342 controls from the same neighborhood or region. Data were gathered with a structured interview and a self-administered food-frequency questionnaire. Nutrient intakes were calculated from the reported food intakes through linkage with the German Federal Food Code and analyzed using multivariate conditional logistic regression to control for total energy intake, educational status, and cigarette smoking. At the macronutrient level, patients reported higher carbohydrate intake than controls after adjustment for total energy intake, smoking, and educational status (OR = 2.74, 95% confidence interval [CI]: 1.30-6.07, for the highest versus lowest quartile, p trend = 0.02). This was reflected in higher monosaccharide and disaccharide intakes at the nutrient level. There was no difference between patients and controls in protein and fat intake after adjustment for energy intake. We found an inverse association between the intakes of beta-carotene (OR = 0.67, 95% CI: 0.37-1.19, p trend = 0.06) and ascorbic acid (OR = 0.60, 95% CI: 0.33-1.09, p trend = 0.04) by patients, although only the trend for ascorbic acid intake reached statistical significance. There was no difference between groups for alpha-tocopherol intake after adjustment for energy intake. We also found that patients reported a significantly lower intake of niacin than controls (OR = 0.15, 95% CI: 0.07-0.33, p trend < 0.00005). Our results suggest that if antioxidants play a protective role in this disease, the amounts provided by diet alone are insufficient. Although the interpretation of the inverse association between niacin intake and PD is complicated by the high niacin content in coffee and alcoholic beverages, which were also inversely associated with PD in this study, the strength of this association and its biologic plausibility warrant further investigation.     

alpha-1-Microglobulin: epidemiological indicator for tubular dysfunction induced by cadmium?

OBJECTIVES: To evaluate the suitability of alpha-1-microglobulin as a marker for cadmium induced renal dysfunction. METHODS: alpha-1-Microglobulin was studied in a cross sectional survey in relation to the body burden of cadmium. Concentrations of alpha-1-microglobulin in 24 h urine of 831 people aged 2-87 years were analysed in association with urinary cadmium excretion, cadmium blood concentration, age, sex, occupational and smoking history, and estimated creatinine clearance. Participants came from a population residentially exposed to cadmium and from two control populations matched for socioeconomic status. RESULTS: The excretion of alpha-1-microglobulin/24 h ranged from 0.1 mg to 176.3 mg and 44.4% of samples showed concentrations near the detection limit. Ordinal logistic regression analysis of people of all ages identified a high risk only for males compared with females (odds ratio (OR) 2.14; 95% confidence interval (95% CI) 1.56 to 2.94), age group, and duration of living on contaminated soil (OR 1.03/year; 95% CI 1.02 to 1.04), but not urinary cadmium excretion (OR 1.30; 95% CI 0.96 to 1.77) as significant predictors. For people < or = 50 years of age a weaker effect of sex (OR 1.76; 95% CI 1.13 to 2.73) and age group and an effect of similar magnitude for the duration of soil exposure (OR 1.03; 95% CI 1.01 to 1.04) were found. Also, the urinary cadmium excretion (OR 2.26; 95% CI 1.38 to 3.70) and occupational exposure (OR 1.71; 95% CI 1.03 to 2.83) were found to be significant in this younger age group. The estimated creatinine clearance had no significant impact on the alpha-1-microglobulin excretion. CONCLUSION: alpha-1-Microglobulin is a suitable marker for early tubular changes only for people < or = 50 years. It may not be sufficiently specific for cadmium, and therefore not a suitable surrogate for cadmium exposure in epidemiological studies.     

A case-control study of multiple myeloma and occupation

Lifetime job histories from a population-based, case-control study were analyzed to investigate the relationship between multiple myeloma and employment in various occupations and industries. Interviews were obtained from 89% (692) of eligible incident cases and 83% (1683) of eligible controls. An elevated risk was observed among persons ever employed as painters [odds ratio (OR) = 2.1, 95% confidence interval (CI) = 1.2-3.6], particularly for those employed for 10 or more years (OR = 4.1, 95% CI = 1.8-10.4). A small excess risk was observed among agricultural workers employed for 10 or more years (OR = 1.3, 95% CI = 1.0-2.2), with a higher relative risk observed among farm laborers (OR = 1.8, 95% CI = 1.0-4.0). Among agricultural workers who reported having been highly exposed to pesticides, the OR was 5.2 (95% CI = 1.6-21.1). Some evidence, based on smaller numbers, was also found to support an association with firefighting and employment in the petroleum- and coal-products manufacturing industries. Little evidence was found to support the previously noted association with wood exposure, and no evidence for an association with employment in the rubber or petroleum refining industries was found. This study lends further support to previously reported associations between multiple myeloma and employment among painters and agricultural workers.     

Cervical root compression monitoring by flexor carpi radialis H-reflex in healthy subjects

BACKGROUND: Contrasting results have been published regarding the risk of breast cancer among teachers and nurses. Confounding by reproductive factors may explain the increased risk observed among women in these occupations as information on those factors were not available in most studies. METHODS: We examined the risk of premenopausal breast cancer among teachers and nurses using occupational histories in a case-control study where information on established risk factors was available. RESULTS: Having ever held a teaching job was not related to breast cancer (OR = 0.74, 95% CI = 0.44-1.28) and women who worked for 10 years or less in this occupation had a non-significant deficit of risk (OR = 0.52, 95% CI = 0.27-1.02). No elevation in risk was found in association with having ever been a nurse (OR = 0.85, 95% CI = 0.45-1.61) or with duration of nursing. Although direct comparison of established risk factors among teachers and nurses and other women in the study showed some evidence of differential distribution, especially when comparing teachers to other women, adjustment for reproductive variables and other breast cancer risk factors did not change the results of this study. CONCLUSION: These findings suggest that teachers and nurses are not at an increased risk of breast cancer. This study also suggests that established risk factors for premenopausal breast cancer may not explain the elevation of risk found in other studies of teachers and nurses. However, this conclusion is limited by the fact that in the present study teachers and nurses had lower than expected breast cancer risk with or without adjustment for established risk factors. Limitations of this study such as low response rates and limited statistical power should be considered in the interpretation of these findings.     

Risk factors for renal cell carcinoma in Denmark. I. Role of socioeconomic status, tobacco use, beverages, and family history

Risk factors for renal cell carcinoma were examined in a population based case-control study in Denmark. A total of 368 cases and 396 age- and gender-matched controls were interviewed in their homes. Increased risk was associated with low socioeconomic status. For men, an increasing risk with decreasing socioeconomic status was seen (odds ratio [OR] = 2.2, 95 percent confidence interval [CI] = 1.0-4.6 for men in the lowest socioeconomic stratum cf the highest). For women, the risk was lower in the highest socioeconomic stratum compared with the rest (OR = 2.4, CI = 0.9-5.9 for the lowest strata cf the highest). Cigarette smoking was a risk factor in men with an OR = 2.3 (CI = 1.1-5.1) for cigarette smokers with a total consumption of more than 40 pack-years compared with nonsmokers. Family history of kidney cancer was associated with an increased risk in both genders (for men, OR = 4.1, CI = 1.1-14.9; for women, OR = 4.8, CI = 1.0-23). Observations were inconsistent regarding coffee and alcohol consumption, and we found no association with tea drinking. The association with socioeconomic status remained after adjustment for other factors.     

Paracrine stimulation of cell growth by cholecystokinin/gastrin through cholecystokinin-B receptor on GH3 cells in vitro

Self-reported reproductive histories of male employees of a lead-zinc smelter were related to pre-conception measures of lead exposure to examine associations between paternal occupational lead exposure and adverse pregnancy outcome. The participants reported 2,021 pregnancies which resulted in 1,684 normal live births, 12 stillbirths, 30 birth defects, 203 spontaneous abortions, and 92 "other" outcomes. Birth defects and stillbirths were combined for the analysis. The risk of a stillbirth or birth defect was elevated for pre-conception employment in a high-lead-exposure compared with a low-lead-exposure job (odds ratio = 2.7, 95% confidence interval = 0.7, 9.6). A similar risk was found for pre-conception blood lead levels of 25-39 μg/dL and >/= 40 μg/dL when compared with blood lead levels of < 25 μg/dL (OR = 2.9, 95% CI = 0.6, 13.3, and OR = 2.5, 95% CI = 0.5, 11.6, respectively). No association was found between pre-conception lead exposure and spontaneous abortion. A relatively low response rate to the questionnaire and potentially erroneous reporting of reproductive outcomes by male workers are limitations of the study.     

Identification and characterization of a constitutive HSP75 in sea urchin embryos

STUDY OBJECTIVE: To evaluate the influence of occupational exposure to carcinogens in explaining the association between socioeconomic status and lung cancer. DESIGN: A prospective cohort study. Data on diet, other lifestyle factors, sociodemographic characteristics and job history were collected by means of a self administered questionnaire. Follow up for incident cancer was established by record linkage with a national pathology register and with regional cancer registries. SETTING: Population originating from 204 municipalities in The Netherlands. PARTICIPANTS: These comprised 58 279 men aged 55-69 years in September 1986. After 4.3 years of follow up there were 470 microscopically confirmed incident lung cancer cases with complete data on dietary habits and job history. MEASUREMENTS AND MAIN RESULTS: Estimation of occupational exposure to asbestos, paint dust, polycyclic aromatic hydrocarbons, and welding fumes was carried out by two experts, using information on job history from the baseline questionnaire. Socioeconomic status was measured by means of highest attained level of education and two indicators based on occupation. In the initial multivariate analyses of socioeconomic status and lung cancer, adjustment was made for age, smoking habits, intake of vitamin C, beta-carotene and retinol, and history of chronic obstructive pulmonary disease or asthma. Additional adjustment for occupational exposure to the four carcinogens mentioned above did not change the inverse association between the level of education and lung cancer risk (initial model: RR highest/lowest level of education = 0.53; 95% CI 0.34, 0.82; additional model: RR highest/lowest level of education = 0.53; 95% CI 0.34, 0.84). Nor was the association between the two occupation based indicators of socioeconomic status and lung cancer risk influenced by occupational exposure to carcinogens. The effect of occupational exposure on the association between the level of education and lung cancer risk did not differ between ex-smokers and current smokers. CONCLUSIONS: Occupational exposure to asbestos, paint dust, polycyclic aromatic hydrocarbons, and welding fumes could not explain the inverse association between socioeconomic status and lung cancer risk. More research which explicitly addresses possible explanations for the association between socioeconomic status and lung cancer risk is needed.     

The role of agricultural pesticide use in the development of non-Hodgkin's lymphoma in women

Non-Hodgkin's lymphoma has been found to be associated with agricultural pesticide use in men, but little is known about the risk in women. In a recent population-based, case-control study conducted in eastern Nebraska, no increased risk of non-Hodgkin's lymphoma was found in women who had ever lived or worked on a farm (odds ratio [OR] = 1.0). Neither the use of insecticides (OR = 0.8) nor herbicides (OR = 0.7) on the farm was associated with non-Hodgkin's lymphoma; however, the number of women who mixed or applied pesticides was small, particularly in comparison to men on farms. Small nonsignificant associations were observed among the women who personally handled insecticides (OR = 1.3) or herbicides (OR = 1.2). Women who personally handled organophosphate insecticides had a significant 4.5-fold increased risk of non-Hodgkin's lymphoma. Use of chlorinated hydrocarbon insecticides was associated with an OR of 1.6; however, the use on dairy cattle was associated with a 3-fold increased risk. Pesticide-related risks were greater among women with a family history of cancer, particularly a history of lymphatic or hematopoietic cancer among first-degree relatives.     

Nontyrosine crystalloids in fine-needle aspiration specimens of the parotid gland: a report of two cases and review of the literature

Transitional-cell carcinoma is the dominant histological type of malignant tumors of the urinary bladder. There is limited information on risk factors for non-transitional-cell carcinoma (NTCC) of the bladder. We used data from 9 case-control studies on bladder cancer from 6 European countries to examine the association between NTCC, tobacco smoking and occupation. Information on 146 cases diagnosed with NTCC were matched by age, gender and study center to 727 non-cancer population or hospital controls and also with 722 transitional-cell-bladder-cancer controls. Lifetime smoking and occupational history were evaluated. A statistically significant excess risk for NTCC was observed for current smoking [odds ratio (OR) = 3.61, 95% confidence interval (CI) 2.08-6.28]. The risk increased with higher tobacco consumption (OR for highest tertile of pack-years = 7.01, 95% CI 3.60-13.66). The risks were higher for squamous-cell carcinomas than for other types of NTCC. Among major occupational groups, a significant excess risk was seen for field-crop and vegetable-farm workers (OR = 2.06, 95% CI 1.03-4.10). These results indicate that NTCC of the bladder is associated with smoking and specific occupations. The risk pattern seems to differ, in part, from that observed for transitional-cell carcinoma of the bladder.     

Older persons'' preferences for site of treatment in acute illness

OBJECTIVES: The objective of this pooled analysis was to examine whether exposure to DDT was associated with the risk of non-Hodgkin's lymphoma among male farmers. METHODS: Data from three case-control studies from four midwestern states in the United States (Nebraska, Iowa, Minnesota, Kansas) were pooled to carry out analyses of 993 cases and 2918 controls. Information on use of agricultural pesticides and other risk factors was based on interviews. Non-farmers (people who had never lived or worked on a farm) were used as a reference category. RESULTS: There were 161 cases and 340 controls who reported use of DDT on animals or crops, or on both, yielding an odds ratio (OR) of 1.2 (95% confidence intervals (95% CI) 1.0 to 1.6). Farmers who had used DDT for > or = 15 years had an OR of 1.5 (95% CI 1.0 to 2.3). Adjustment for respondent status and use of other pesticides resulted in slightly reduced ORs. Analyses by the number of days of use a year was limited to the Nebraska data. The most notable increase was found among farmers who used DDT for > or = 5 days a year (OR 2.6, 95% CI 1.1 to 5.9); however, additional adjustment for use of organophosphates, phenoxyacetic acids, and the individual pesticides lindane, malathion, and atrazine reduced the ORs to 1.0, 0.9, 1.1, 1.6, and 1.9 respectively. CONCLUSIONS: No strong consistent evidence was found for an association between exposure to DDT and risk of non-Hodgkin's lymphoma. It seems that the excess risk initially found may be explained by use of other pesticides.     

Immunological markers among workers exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin

OBJECTIVES: To examine the association of immune cell number and function with occupational exposure to substances contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). METHODS: A cross sectional medical survey. The exposed participants were employed at two chemical plants between 1951 and 1972 in the manufacture of 2,4,5-trichlorophenate and its derivatives. The reference group consisted of people with no occupational exposure to phenoxy herbicides who lived within the communities of the workers. Data from a total of 259 workers and 243 unexposed referents were included in the analysis of immune function. Laboratory tests for immune status included enumeration of circulating leukocyte and lymphocyte populations, proliferative responses of circulating lymphocytes to mitogens and antigens, and serum concentrations of the major immunoglobulins and complement factor C3. RESULTS: The workers had substantial exposure to substances contaminated with TCDD, as indicated by a lipid adjusted mean serum TCDD concentration of 229 ppt compared with a mean of 6 ppt in the unexposed referents. Workers were divided into categories based on their serum TCDD concentration. For all categories except the lowest, with values of serum TCDD comparable with the unexposed referents, there were increased odds of having lower counts of CD26 cells (activated T cells) (odds ratio (OR) 1.0, 95% confidence interval (95% CI) 0.5 to 1.8 for TCDD < 20 ppt; OR 1.6, 95% CI 0.8 to 3.2 for TCDD 20-51 ppt; OR 2.7, 95% CI 1.4 to 5.1 for TCDD 52-125 ppt; OR 2.6, 95% CI 1.4 to 4.9 for TCDD 125-297 ppt; OR 2.4, 95% CI 1.3 to 4.6 for TCDD 298-3389 ppt). A less consistent finding was decreased spontaneous proliferation of cultured lymphocytes. However, increases were found in proliferation of lymphocytes in response to concanavalin and pokeweed in workers in the high TCDD category. Age, cigarette smoking, and alcohol were significant predictors of several immunological outcomes. CONCLUSIONS: Associations between serum TCDD concentration and both a decrease in circulating CD26 cells and decreased spontaneous background proliferation were the major findings of this study. These results are unlikely to be of clinical importance but may reflect limited evidence for an association between immunological changes in workers and high serum concentrations of TCDD, or chance findings resulting from the evaluation of multiple immunological variables.     

Nested case-control study of esophageal cancer in relation to occupational exposure to silica and other dusts

BACKGROUND: Standardized proportionate mortality ratio (SPMR) was found to be 2.2 (95% CI = 1.3-3.5) for esophageal cancer (EC) among workers exposed to refractory brick dust in a large iron-steel complex in China. METHODS: A nested case-control design within a cohort of industrial workers. One hundred and twenty-five EC cases and 250 controls were identified from the death registry file. Interviews were conducted of the next of kin for past exposure information on job, domestic, and lifestyle factors. History of occupational exposure to various dusts was reconstructed from personnel files and by interviewing colleagues utilizing a job-exposure matrix. RESULTS: After adjusting for confounders, occupational exposure to silica dust was the most important risk factor among all variables investigated, with a 2.8-fold risk and a clear dose-response by length of exposure. Alcohol drinking (OR = 1.8) and coal cooking (OR = 2.0) were risk factors and high consumption of fruit diet (OR = 0.5) and meat diet (OR = 0.6) were protective factors. CONCLUSIONS: The relationship between occupational exposure to silica dust and the risk of EC found in an earlier SPMR study was confirmed. Ingestion of silica particles after lung clearance may increase the risk of EC among workers exposed to silica.     

Timing of menopause, reproductive years, and bone mineral density: a cross-sectional study of postmenopausal Japanese women

Age at menopause has been found to be associated positively with bone mineral density, and age at menarche has been found to be associated negatively with bone mineral density. However, there have been few studies on the relations of timing of menopause and length of the reproductive period with bone mineral density. The purpose of this study was to examine the relations of timing of menopause and reproductive years (calculated as age at menopause minus age at menarche) with mineral density of the second metacarpal bone in postmenopausal Japanese women. The study population consisted of 1,035 naturally menopausal women aged 40-70 years who were screened in 1996-1997. Using computed x-ray densitometry, the authors measured bone mineral density by analyzing radiographic films of the right second metacarpal bone. Using the women with early menopause (age < 49 years) as the reference group and adjusting for age, subjects with late menopause were at decreased risk for low bone mineral density (odds ratio (OR) = 0.69, 95% confidence interval (CI) 0.49-0.97). After adjustment for additional covariates (grip strength, physical activity, body mass index, smoking, and calcium intake), the association was unchanged (OR = 0.70, 95% CI 0.50-0.99). Postmenopausal women with more reproductive years (> or = 40 years) were at decreased risk for low bone mineral density compared with those with fewer reproductive years, after adjustment for age (OR = 0.73, 95% CI 0.40-1.30) and potentially confounding factors (OR = 0.76, 95% CI 0.41-1.37); the p-value for trend was not statistically significant. In multiple linear regression analysis, early menopause and fewer reproductive years were independent predictors of low bone mineral density. In this study, postmenopausal Japanese women who had a late menopause and more reproductive years were at decreased risk for low bone mineral density, and may therefore be less prone to osteoporosis.     

Factors associated with self-reported, pesticide-related visits to health care providers in the agricultural health study

To investigate factors associated with pesticide-related visits to health care providers (i.e., doctor or hospital visits), responses to self-administered questionnaires received from 35,879 licensed restricted-use pesticide applicators participating in the Agricultural Health Study were analyzed. (In Iowa, applicators are actually certified, whereas in North Carolina they are licensed; for ease of reference, the term license will be used for both states in this paper.) The cohort reported a total of more than 10.9 million pesticide-application days. These applications were associated with one or more pesticide-related health care visits by 2,214 applicators (7.0% of the applicator cohort for whom health care visit data were available). The odds of a pesticide-related health care visit were increased for commercial applicators compared to private applicators [odds ratio (OR = 1.77; 95% confidence interval (CI), 1.52-2.06) and for applicators who used insecticides 70 times or more in their lifetime compared to those who used insecticides less frequently (OR = 1.43; CI, 1.26-1.63). After adjusting for the number of applications in a logistic regression model, significantly higher odds of health care visits were observed among North Carolina applicators compared to Iowa applicators (OR = 1.35; CI, 1.17-1.52), among applicators who mixed their own pesticides (OR = 1.65; CI, 1. 22-2.23), and among applicators who personally repaired their pesticide application equipment at least once per year (OR = 1.12; CI, 1.06-1.25). Significantly lower odds were found among female versus male applicators (OR = 0.68; CI, 0.46-0.99) and among applicators who graduated from high school versus those who did not (OR = 0.82; CI, 0.71-0.94 for high school graduates and OR = 0.79; CI, 0.68-0.91 for those with at least some college). Several methods of pesticide application to crops, seed, or stored grain were also associated with significantly elevated odds ratios of health care visits. These observations suggest that several steps can be taken to reduce the number of health care visits resulting from occupational exposure to pesticides. The implications of this pattern of pesticide-related health care visits may have etiologic implications for cancer and other chronic diseases.     

Race, asthma, and persistent wheeze in Philadelphia schoolchildren

OBJECTIVES: Many studies show asthma to be more common in Black than in White children. This study assessed how much of this difference remains after adjustment for other potentially race-associated predictors of asthma. METHODS: We assessed the predictors of active diagnosed asthma and persistent wheeze in 1416 Black and White Philadelphia children aged 9 to 11 years, as reported by parents. RESULTS: Black race remained a significant predictor of active diagnosed asthma (odds ratio [OR] = 2.3; 95% confidence interval [CI] = 1.3, 4.1) but not of persistent wheeze (OR = 1.0; 95% CI = 0.6, 1.8). The excess risk of asthma in Black children was not appreciably altered by adjustment for other demographic and environmental factors. CONCLUSIONS: Black race is an important risk factor for active diagnosed asthma in these urban children, a relationship not explained by social factors. This finding and the lack of an association of race with persistent wheeze after adjustment for social factors suggest that race may be more important to the acquisition of an asthma diagnosis than to the prevalence of the symptoms.