Proportionate mortality of crop and livestock farmers in the United States, 1984-1993

Occupational Exposures and Risks of Non-Hodgkin Lymphoma: A Meta-Analysis

Non-Hodgkin lymphoma (NHL) is a heterogeneous group with different types of diseases. It remains unclear as to what has led to an increase in incidences of NHL, however, chemical substance exposure is known to be one of the risk factors for the disease. Therefore, we performed a systematic review and meta-analysis including case-control, cohort, and cross-sectional observational epidemiological studies to verify the association between occupational exposure to carcinogens and NHL risk. Articles between the years 2000 and 2020 were collected. Two different reviewers performed a blind selection of the studies using the Rayyan QCRI web app. Post-completion, the selected articles were extracted and analyzed via the RedCap platform. Our review resulted in 2719 articles, of which 51 were included in the meta-analysis, resulting in an overall OR of 1.27 (95% CI 1.04-1.55). Furthermore, it was observed that the main occupation associated with the increased risk of NHL was that in which workers are exposed to pesticides. We therefore conclude that the evidence synthesis of the epidemiological literature supports an increased risk for NHL, regardless of subtype, considering occupational exposure to certain chemical compounds, mainly pesticides, benzene, and trichlorethylene, and certain classes of work, primarily in the field of agriculture.

Farming, Pesticides, and Brain Cancer: A 20-Year Updated Systematic Literature Review and Meta-Analysis

Twenty additional years of epidemiologic literature have become available since the publication of two meta-analyses on farming and brain cancer in 1998. The current systematic literature review and meta-analysis extends previous research and harmonizes findings. A random effects model was used to calculate meta-effect estimates from 52 studies (51 articles or reports), including 11 additional studies since 1998. Forty of the 52 studies reported positive associations between farming and brain cancer with effect estimates ranging from 1.03 to 6.53. The overall meta-risk estimate was 1.13 (95% CI = 1.06, 1.21), suggesting that farming is associated with a 13% increase in risk of brain cancer morbidity or mortality. Farming among white populations was associated with a higher risk of brain cancer than among non-white populations. Livestock farming (meta-RR = 1.34; 95% CI = 1.18, 1.53) was associated with a greater risk compared with crop farming (meta-RR = 1.13; 95% CI = 0.97, 1.30). Farmers with documented exposure to pesticides had greater than a 20% elevated risk of brain cancer. Despite heterogeneity among studies, we conclude that the synthesis of evidence from 40 years of epidemiologic literature supports an association between brain cancer and farming with its potential for exposure to chemical pesticides.

Excessive Pesticide Use Likely to Cause the Onset of Myasthenia Gravis in the Moroccan Agricultural Population

BACKGROUND AND OBJECTIVE

As pesticides have been and are widely used in agriculture. This work consists of highlighting one of the probable consequences of these xenobiotics. The aim of the study is possible association between the onset of autoimmune disorders and the exposure of rural populations to toxic substances will be discussed.

MATERIALS AND METHODS

To carry out this work, the data recorded in the medical records of myasthenic men and women living in the countryside were used. Of all the 117 cases withdrawn from the specialties hospital in Rabat (Morocco), 77% lived in urban areas and 23% in rural areas.

RESULTS

The result of the analysis of the files of rural inhabitants revealed a male predominance, unlike previous data on the distribution of myasthenia gravis by sex, women were in the lead in terms of quantity for this disease.

CONCLUSION

These findings may lead to highlight exposure to pesticides and their accumulation during the time spent by these agricultural workers in the fields and sometimes without appropriate personal protective equipment.

Association between intake of fruits and vegetables by pesticide residue status and coronary heart disease risk

BACKGROUND

Fruit and vegetable (FV) intake is recommended for the prevention of coronary heart disease (CHD). FVs are also an important source of exposure to pesticide residues. Whether the relations of FV intake with CHD differ according to pesticide residue status is unknown.

OBJECTIVE

To examine the associations of high- and low-pesticide-residue FVs with the risk of CHD.

METHODS

We followed 145,789 women and 24,353 men free of cardiovascular disease and cancer (excluding non-melanoma skin cancer) at baseline and participating in three ongoing prospective cohorts: the Nurses' Health Study (NHS: 1998-2012), the NHS-II (1999-2013), and the Health Professionals Follow-up Study (HPFS: 1998-2012). FV intake was assessed via food frequency questionnaires. We categorized FVs as having high- or low-pesticide-residues using a validated method based on pesticide surveillance data from the US Department of Agriculture. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (95%CI) of CHD in relation to high- and low-pesticide-residue FV intake.

RESULTS

A total of 3707 incident CHD events were identified during 2,241,977 person-years of follow-up. In multivariable-adjusted models, a greater intake of low-pesticide-residue FVs was associated with a lower risk of CHD whereas high-pesticide-residue FV intake was unrelated to CHD risk. Specifically, compared with individuals consuming <1 serving/day of low-pesticide-residue FVs, those consuming ≥4 servings/day had 20% (95CI: 4%, 33%) lower risk of CHD. The corresponding HR (comparing ≥4 servings/day to <1 serving/day) for high-pesticide-residue FV intake and CHD was 0.97 (95%CI: 0.72, 1.30).

CONCLUSIONS

Our data suggested exposure to pesticide residues through FV intake may modify some cardiovascular benefits of FV consumption. Further confirmation of these findings, especially using biomarkers for assessment of pesticide exposure, is needed.

Helicobacter suis Is Associated With Mortality in Parkinson's Disease

Helicobacter pylori has been implicated in the pathogenesis of Parkinson's disease (PD). Its eradication, in a randomized placebo-controlled trial, improved PD hypokinesia. Helicobacter species zoonosis might explain excess mortality from PD and non-Hodgkin lymphoma in livestock, but not arable, farmers. Indeed, Helicobacter is causally-associated with gastric lymphoma. We have previously shown that the relative-frequency, H. suis to H. pylori, was 10-times greater in 60 PD-patients than in 256 controls. We now go on to evaluate the pathological significance of H. suis, detected in gastric-biopsy DNA-extracts by ureA-based species-specific qPCR, validated by amplicon sequencing. The methodology had been cross-validated by a carR-based PCR. The pathological significance is put in context of H. pylori detection [urea-breath-test (UBT) with biopsy-culture, and, if negative, PCR], and the potential reservoir in pigs. Here, we explore, in these 60 PD-patients, associations of H. suis status with all-cause-mortality, and with orthostatic cardiovascular and blood profiling. H. suis had been detected in 19 of the 60 PD-patients on one or more occasion, only two (with co-existent H. pylori) being UBT positive. We found that the hazard-of-death (age-at-diagnosis- and gender-adjusted) was 12 (95% CI 1,103) times greater (likelihood-ratio test, P = 0.005) with H. suis-positivity (6/19) than with negativity (2/40: one lost to follow-up). UBT-values did not influence the hazard. H. suis-positivity was associated with lower standing mean-arterial-pressure [6 (1, 11) mmHg], H. pylori-positivity having no effect. The lower total lymphocyte count with H. pylori-positivity [-8 (-1, -14) %] was not seen with H. suis, where T-cell counts were higher [24 (2, 52) %]. Regarding the potential zoonotic reservoir in the UK, Helicobacter-like-organism frequency was determined in freshly-slaughtered pigs, nature ascertained by sequencing. Organisms immunostaining for Helicobacter, with corkscrew morphology typical of non-H. pylori Helicobacter, were seen in 47% of 111 pig-antra. We conclude that H. suis is associated with all-cause-mortality in PD and has a potential zoonotic reservoir.

Overall and cause-specific mortality in a cohort of farmers and their spouses

OBJECTIVES

Lower mortality rates compared with the general population have been reported for Agricultural Health Study (AHS) participants (enrolled 1993-1997) followed through 2007. We extended analysis of mortality among AHS participants (51 502 private pesticide applicators, their 31 867 spouses and 4677 commercial pesticide applicators from North Carolina and Iowa) through 2015 and compared results using several analytical approaches.

METHODS

We calculated standardised mortality ratios (SMRs), causal mortality ratios (CMR) and relative SMRs (rSMR) using state-specific mortality rates of the general populations as the referent.

RESULTS

Over the average 16 years of follow-up (1999-2015), 9305 private applicators, 3384 spouses and 415 commercial applicators died. SMRs and CMRs, with expected deaths calculated using the person-time among the cohort and the general population, respectively, indicated lower overall mortality in all study subgroups (SMRs from 0.61 to 0.69 and CMRs from 0.74 to 0.89), although CMRs indicated elevated mortality in private applicators from North Carolina and in ever-smokers. In SMR analyses, there were fewer than expected deaths from many causes, but deaths from some external causes including transportation-related injuries and mechanical forces were elevated in private applicators. CMRs indicated higher than expected deaths from prostate cancer, lymphohaematopoietic cancers, Parkinson's and Alzheimer's disease, and chronic glomerulonephritis in private applicators, and non-Hodgkin's lymphoma in spouses (from 1.19 to 1.53). rSMR results were generally elevated, similar to CMR findings.

CONCLUSIONS

AHS participants experienced lower overall mortality than the general population.Mortality from a few specific causes was increased in private applicators, specifically when CMR and rSMR approaches were used.

Lifetime Pesticide Use and Antinuclear Antibodies in Male Farmers From the Agricultural Health Study

Farming and pesticide use have been associated with systemic autoimmune diseases, and while certain organochlorine insecticides and other pesticides are suspected to influence risk, the role of specific pesticides in the development of systemic autoimmunity is not known. We measured serum antinuclear autoantibodies (ANA) by immunofluorescence on Hep-2 cells in 668 male farmers in the study of Biomarkers of Exposure and Effect in Agriculture (BEEA; 2010-2013), an Agricultural Health Study (AHS) subcohort. We examined ANA in relation to lifetime use of 46 pesticides first reported at AHS enrollment (1993-1997) and updated at intervals through BEEA enrollment. Odds ratios (OR) and 95% confidence intervals (CI) were estimated after adjusting for age, state, education, season of blood draw, current pesticide use, and correlated pesticides. Having ANA antibodies (3 or 4+ intensity at a 1:80 dilution, 21% of study participants) was associated with a reported history of seeking medical care due to exposure to pesticides (OR 2.15; 95%CI 1.17, 3.95), use of the fumigant methyl bromide (OR 3.16; 95%CI 1.05, 9.5), and use of petroleum oil/distillates (OR 1.50; 95%CI 1.00, 2.25). Using a higher threshold (3 or 4+ at a 1:160 dilution, 9%) ANA positivity was associated with the carbamate insecticide aldicarb (OR 4.82; 95%CI 1.33, 17.5) and greater combined use of four cyclodiene organochlorine insecticides (top tertile of intensity-weighted lifetime days vs. no use; OR T3 3.20; 95%CI 1.10, 9.27). By contrast, greater use of non-cyclodiene organochlorine insecticides was inversely associated with ANA (1:80 dilution 3 or 4+, OR T3 0.24; 95%CI 0.08, 0.72). Specific autoantibodies (to extractable nuclear antigens and anti-dsDNA), measured on those with ANA detected at the 1:80 dilution 3 or 4+, were seen in 15 individuals (2%), and were associated with use of two or more cyclodiene organochlorine insecticides and several other pesticides (e.g., carbofuran, ethylene dibromide). These findings suggest that specific pesticide exposures may have long-term effects on ANA prevalence and support the hypothesis that certain organochlorine insecticides may increase the risk of developing systemic autoimmunity.

Pesticide use, allergic rhinitis, and asthma among US farm operators

OBJECTIVE

The objective of the study is to examine associations between use of specific pesticides and lifetime allergic rhinitis and current asthma in US primary farm operators.

METHODS

The 2011 Farm and Ranch Safety Survey data from 11,210 primary farm operators were analyzed. Pesticide use on the farm was determined using an affirmative response to the question of whether the operator ever mixed, loaded, or applied pesticides on their farm in the 12 months prior to the interview. Operators who answered "yes" were further asked about the specific trade name and formulation identifiers of the product they used and personal protective equipment (PPE) used. Data were weighted to produce national estimates. Adjusted prevalence odds ratios (PORs) were calculated using logistic regression. The referent group included operators who did not use any pesticides in the 12 months prior to the interview.

RESULTS

Of an estimated 2.1 million farm operators, 40.0% used pesticides, 30.8% had lifetime allergic rhinitis, and 5.1% had current asthma. Insecticide and herbicide use were significantly associated with lifetime allergic rhinitis and current asthma. The use of 2,4-dichlorophenoxyacetic acid (POR = 1.5; 95% CI 1.2-1.9) and carbaryl (POR = 2.3; 1.4-3.7) was significantly associated with lifetime allergic rhinitis. Of operators using pesticides, 64.9% used PPE the last time they mixed, loaded, or applied pesticides.

CONCLUSIONS

Pesticide use was associated with lifetime allergic rhinitis and current asthma among farm operators. Further studies are needed to clarify the dose-response relationship between pesticide use and adverse respiratory health effects.

Farming tasks and the development of rheumatoid arthritis in the agricultural health study

OBJECTIVES

Farming has been associated with rheumatoid arthritis (RA). Some studies have evaluated the effects of pesticides, but other agricultural exposures may also affect immune response.

METHODS

We investigated non-pesticide agricultural exposures in relation to RA in licensed pesticide applicators (n=27 175, mostly male farmers) and their spouses (n=22 231) in the Agricultural Health Study (AHS) cohort (1993-1997) who completed at least one follow-up survey through 2015. Incident RA cases (n=229 applicators and 249 spouses) were identified based on self-report confirmed by use of disease-modifying antirheumatic drugs or medical records. Hazard Ratios (HRs) and 95% Confidence Intervals (CIs) were estimated by Cox proportional hazard models adjusting for applicator status, state, smoking, education and specific pesticide use, allowing estimates to vary by median age when hazards assumptions were not met.

RESULTS

Overall, RA was associated with regularly applying chemical fertilisers (HR=1.50; 95% CI 1.11 to 2.02), using non-gasoline solvents (HR=1.40; 95% CI 1.09 to 1.80), and painting (HR=1.26; 95% CI 1.00 to 1.59). In older applicators (>62 years), RA was associated with driving combines (HR=2.46; 95% CI 1.05 to 5.78) and milking cows (HR=2.56; 95% CI 1.01 to 6.53). In younger participants (≤62 years), RA was inversely associated with raising animals as well as crops (HR=0.68; 95% CI 0.51 to 0.89 vs crops only). Associations with specific crops varied by age: some (eg, hay) were inversely associated with RA in younger participants, while others (eg, alfalfa) were associated with RA in older participants.

CONCLUSION

These findings suggest several agricultural tasks and exposures may contribute to development of RA.

Baseballs, tennis balls, livestock farm manure, the IDH1 mutation, endothelial cell proliferation and hypoxic pseudopalisading (granulomatous) necrosis: Mycobacterium avium subspecies paratuberculosis and the epidemiology, cellular metabolism and histology of diffuse gliomas, including glioblastoma

An increased rate of diffuse gliomas, including glioblastoma, has been noted in livestock farmers in Western countries. Some researchers have suggested that a zoonotic virus or bacteria present in the livestock animal’s feces or manure may be a possible etiologic factor. Mycobacterium avium subspecies paratuberculosis (MAP), the cause of a chronic enteropathy in domestic livestock and a probable zoonosis, is heavily excreted in an infected animal’s feces or manure, contaminating soil and ground on the animal’s farm. Once excreted in an animal’s feces, MAP lasts indefinitely in a dormant but viable form, and easily spreads outside farms to the surrounding environment. MAP’s presence throughout the soil in countries where MAP infection of domestic livestock is extensive and long-standing may explain the increased rates of glioblastoma in tennis and baseball players who handle balls coated with MAP-contaminated dirt. MAP infection is consistent with glioblastoma’s two defining histopathologic characteristics: endothelial cell proliferation and pseudopalisading necrosis. MAP is a non-tuberculous or atypical mycobacterium, which can cause hypoxic necrotizing granulomas, granulomas that resemble areas of pseudopalisading necrosis. There are known bacterial causes of endothelial cell proliferation. Almost unique amongst intracellular bacteria, MAP’s variant isocitrate dehydrogenase 1 (IDH1) enzyme, a type 2-oxoglutarate ferredoxin oxidoreductase, can use a host cell’s cytosolic α-ketoglutarate in its own Krebs or tricarboxylic acid cycle. MAP’s ability to use a host cell’s α-ketoglutarate may explain the survival advantage of the cytosolic IDH1 enzyme mutation for patients with diffuse gliomas including glioblastoma, astrocytoma, and oligdendroglioma, a mutation that results in a reduced supply of cytosolic α-ketoglutarate. MAP may therefore be one possible infectious cause of glioblastoma and the other histologic categories of diffuse glioma.

Abnormal Plasma Cell Disorders in Refinery Waste Workers

A monoclonal gammopathy of undetermined significance (MGUS) may develop into a multiple myeloma or a correlated lymphoproliferative malignancy with a progress rate of 1% per year. The immune status, occupational-environmental risk factors, and hereditary factors may influence the risk of developing MGUS. We investigated the prevalence of MGUS in 77 refinery waste workers. They were all males, averagely aged 36, with a mean working history of 18.5 years and working in the dump for about 4.2 years. After analyzing the results of standard serum electrophoresis migrations, 16% of cases (n = 12) showed levels beyond the normal ranges. In all 12 samples we observed an increase of gamma component: 67%, IgG; 17%, IgM; 8%, IgA; 8%, oligoclonal. Workers were exposed to hazardous refinery waste. After the biological monitoring of urine samples for metals and t,t-muconic acid, no extra-range values were observed. The multivariate analysis shows, however, that cigarette smoking and residence near industrial sites are significantly (p < 0.001) associated with a high risk of MGUS development; while no association was found with occupational exposure. Additional attention might be paid in particular to these conditions in epidemiological studies and further larger, prospective, population-based researches appear warranted to evaluate the strength of any positive association.

Childhood Residential and Agricultural Pesticide Exposures in Relation to Adult-Onset Rheumatoid Arthritis in Women

Farming and pesticide exposure may influence risk of rheumatoid arthritis (RA); the role of early-life pesticide exposure is unknown. The Sister Study includes a US national cohort of women aged 35-74 years (enrolled 2004-2009); we examined childhood pesticide exposure in women in this cohort with adult-onset RA. Cases (n = 424) were compared with 48,919 noncases. Data included pesticide use at the longest childhood residence through age 14 years, farm residence of at least 12 months with agricultural pesticide exposure through age 18 years, and maternal farm experience. Odds ratios and 95% confidence intervals were adjusted for age, race or ethnicity, education, smoking, and childhood socioeconomic factors. Cases with RA reported more frequent and direct (personal) residential pesticide use in childhood (for infrequent/indirect pesticide use, odds ratio (OR) = 1.1; for frequent/direct use, OR = 1.8; P for trend = 0.013). Compared with women without residential farm history, odds of having RA increased for those reporting a childhood-only farm residence with personal exposure to pesticides used on crops (OR = 1.8, 95% confidence interval: 1.1, 2.9) or livestock (OR = 2.0, 95% confidence interval: 1.2, 3.3). Our findings suggest adult-onset RA may be related to childhood exposure to residential and agricultural pesticides, and support further investigations of lifetime pesticide use in RA.

Clinical characteristics of chronic lymphocytic leukemia occurring in chornobyl cleanup workers

The recently demonstrated radiation-induction of chronic lymphocytic leukemia (CLL) raises the question as to whether the amount of radiation exposure influences any of the clinical characteristics of the disease. We evaluated the relationship between bone marrow radiation doses and clinical characteristics and survival of 79 CLL cases diagnosed during 1986-2006 in a cohort of 110 645 male workers who participated in the cleanup work of the Chornobyl nuclear accident in Ukraine in 1986. All diagnoses were confirmed by an independent International Hematology Panel. Patients were followed up to the date of death or end of follow-up on 31 October 2010. The median age at diagnosis was 57 years. Median bone marrow dose was 22.6 milligray (mGy) and was not associated with time between exposure and clinical diagnosis of CLL (latent period), age, peripheral blood lymphocyte count or clinical stage of disease in univariate and multivariate analyses. Latent period was significantly shorter among those older at first exposure, smokers and those with higher frequency of visits to the doctor prior to diagnosis. A significant increase in the risk of death with increasing radiation dose was observed (p = 0.03, hazard ratio = 2.38, 95% confidence interval: 1.11,5.08 comparing those with doses ≥22 mGy to doses <22 mGy). After adjustment for radiation dose, survival of CLL cases was significantly shorter among those with younger age at first exposure, higher peripheral blood lymphocyte count, more advanced clinical stage of disease and older age at diagnosis (all p < 0.05). This is the first study to examine association between bone marrow radiation doses from the Chornobyl accident and clinical manifestations of the CLL in Chornobyl cleanup workers. The current study provides new evidence on the association of radiation dose and younger age at first radiation exposure at Chornobyl with shorter survival after diagnosis. Future studies are necessary with more cases in order to improve the statistical power of these analyses and to determine their significance. Copyright © 2016 John Wiley & Sons, Ltd.

Rheumatoid Arthritis in Agricultural Health Study Spouses: Associations with Pesticides and Other Farm Exposures

BACKGROUND

Farming has been associated with rheumatoid arthritis (RA), but the role of pesticides is not known.

OBJECTIVES

We examined associations between RA and pesticides or other agricultural exposures among female spouses of licensed pesticide applicators in the Agricultural Health Study.

METHODS

Women were enrolled between 1993 and 1997 and followed through 2010. Cases (n = 275 total, 132 incident), confirmed by a physician or by self-reported use of disease modifying antirheumatic drugs, were compared with noncases (n = 24,018). Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression models adjusted for age, state, and smoking pack-years.

RESULTS

Overall, women with RA were somewhat more likely to have reported lifetime use of any specific pesticide versus no pesticides (OR = 1.4; 95% CI: 1.0, 1.6). Of the 15 pesticides examined, maneb/mancozeb (OR = 3.3; 95% CI: 1.5, 7.1) and glyphosate (OR = 1.4; 95% CI: 1.0, 2.1) were associated with incident RA compared with no pesticide use. An elevated, but non-statistically significant association with incident RA was seen for DDT (OR = 1.9; 95% CI: 0.97, 3.6). Incident RA was also associated with the application of chemical fertilizers (OR = 1.7; 95% CI: 1.1, 2.7) and cleaning with solvents (OR = 1.6; 95% CI: 1.1, 2.4), but inversely associated with lifetime livestock exposure as a child and adult (OR = 0.48; 95% CI: 0.24, 0.97) compared with no livestock exposure.

CONCLUSIONS

Our results suggest that specific agricultural pesticides, solvents, and chemical fertilizers may increase the risk of RA in women, while exposures involving animal contact may be protective. Citation: Parks CG, Hoppin JA, De Roos AJ, Costenbader KH, Alavanja MC, Sandler DP. 2016. Rheumatoid arthritis in Agricultural Health Study spouses: associations with pesticides and other farm exposures. Environ Health Perspect 124:1728-1734; http://dx.doi.org/10.1289/EHP129.

Association between Parkinson's Disease and Cigarette Smoking, Rural Living, Well-Water Consumption, Farming and Pesticide Use: Systematic Review and Meta-Analysis

Objective

Bradford Hill’s viewpoints were used to conduct a weight-of-the-evidence assessment of the association between Parkinson’s disease (PD) and rural living, farming and pesticide use. The results were compared with an assessment based upon meta-analysis. For comparison, we also evaluated the association between PD and cigarette smoking as a “positive control” because a strong inverse association has been described consistently in the literature.

Methods

PubMed was searched systematically to identify all published epidemiological studies that evaluated associations between Parkinson’s disease (PD) and cigarette smoking, rural living, well-water consumption, farming and the use of pesticides, herbicides, insecticides, fungicides or paraquat. Studies were categorized into two study quality groups (Tier 1 or Tier 2); data were abstracted and a forest plot of relative risks (RRs) was developed for each risk factor. In addition, when available, RRs were tabulated for more highly exposed individuals compared with the unexposed. Summary RRs for each risk factor were calculated by meta-analysis of Tier 1, Tier 2 and all studies combined, with sensitivity analyses stratified by other study characteristics. Indices of between-study heterogeneity and evidence of reporting bias were assessed. Bradford Hill’s viewpoints were used to determine if a causal relationship between PD and each risk factor was supported by the weight of the evidence.

Findings

There was a consistent inverse (negative) association between current cigarette smoking and PD risk. In contrast, associations between PD and rural living, well-water consumption, farming and the use of pesticides, herbicides, insecticides, fungicides or paraquat were less consistent when assessed quantitatively or qualitatively.

Conclusion

The weight of the evidence and meta-analysis support the conclusion that there is a causal relationship between PD risk and cigarette smoking, or some unknown factor correlated with cigarette smoking. There may be risk factors associated with rural living, farming, pesticide use or well-water consumption that are causally related to PD, but the studies to date have not identified such factors. To overcome the limitations of research in this area, future studies will have to better characterize the onset of PD and its relationship to rural living, farming and exposure to pesticides.

Occupation and Risk of Non-Hodgkin Lymphoma and Its Subtypes: A Pooled Analysis from the InterLymph Consortium

BACKGROUND

Various occupations have been associated with an elevated risk of non-Hodgkin lymphoma (NHL), but results have been inconsistent across studies.

OBJECTIVES

We investigated occupational risk of NHL and of four common NHL subtypes with particular focus on occupations of a priori interest.

METHODS

We conducted a pooled analysis of 10,046 cases and 12,025 controls from 10 NHL studies participating in the InterLymph Consortium. We harmonized the occupational coding using the 1968 International Standard Classification of Occupations (ISCO-1968) and grouped occupations previously associated with NHL into 25 a priori groups. Odds ratios (ORs) adjusted for center, age, and sex were determined for NHL overall and for the following four subtypes: diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and peripheral T-cell lymphoma (PTCL).

RESULTS

We confirmed previously reported positive associations between NHL and farming occupations [field crop/vegetable farm workers OR = 1.26; 95% confidence interval (CI): 1.05, 1.51; general farm workers OR = 1.19; 95% CI: 1.03, 1.37]; we also confirmed associations of NHL with specific occupations such as women's hairdressers (OR = 1.34; 95% CI: 1.02, 1.74), charworkers/cleaners (OR = 1.17; 95% CI: 1.01, 1.36), spray-painters (OR = 2.07; 95% CI: 1.30, 3.29), electrical wiremen (OR = 1.24; 95% CI: 1.00, 1.54), and carpenters (OR = 1.42; 95% CI: 1.04, 1.93). We observed subtype-specific associations for DLBCL and CLL/SLL in women's hairdressers and for DLBCL and PTCL in textile workers.

CONCLUSIONS

Our pooled analysis of 10 international studies adds to evidence suggesting that farming, hairdressing, and textile industry-related exposures may contribute to NHL risk. Associations with women's hairdresser and textile occupations may be specific for certain NHL subtypes.

CITATION

't Mannetje A, De Roos AJ, Boffetta P, Vermeulen R, Benke G, Fritschi L, Brennan P, Foretova L, Maynadié M, Becker N, Nieters A, Staines A, Campagna M, Chiu B, Clavel J, de Sanjose S, Hartge P, Holly EA, Bracci P, Linet MS, Monnereau A, Orsi L, Purdue MP, Rothman N, Lan Q, Kane E, Seniori Costantini A, Miligi L, Spinelli JJ, Zheng T, Cocco P, Kricker A. 2016. Occupation and risk of non-Hodgkin lymphoma and its subtypes: a pooled analysis from the InterLymph Consortium. Environ Health Perspect 124:396-405; http://dx.doi.org/10.1289/ehp.1409294.

Agent Orange Exposure and Monoclonal Gammopathy of Undetermined Significance: An Operation Ranch Hand Veteran Cohort Study

IMPORTANCE

Multiple myeloma has been classified as exhibiting "limited or suggestive evidence" of an association with exposure to herbicides in Vietnam War veterans. Occupational studies have shown that other pesticides (ie, insecticides, herbicides, fungicides) are associated with excess risk of multiple myeloma and its precursor state, monoclonal gammopathy of undetermined significance (MGUS); however, to our knowledge, no studies have uncovered such an association in Vietnam War veterans.

OBJECTIVE

To examine the relationship between MGUS and exposure to Agent Orange, including its contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), in Vietnam War veterans.

DESIGN, SETTING, AND PARTICIPANTS

This was a prospective cohort study conducted in 2013 to 2014, testing for MGUS in serum specimens collected and stored in 2002 by the Air Force Health Study (AFHS). The relevant exposure data collected by the AFHS was also used. We tested all specimens in 2013 without knowledge of the exposure status. The AFHS included former US Air Force personnel who participated in Operation Ranch Hand (Ranch Hand veterans) and other US Air Force personnel who had similar duties in Southeast Asia during the same time period (1962 to 1971) but were not involved in herbicide spray missions (comparison veterans). Agent Orange was used by the US Air Force personnel who conducted aerial spray missions of herbicides (Operation Ranch Hand) in Vietnam from 1962 to 1971. We included 479 Ranch Hand veterans and 479 comparison veterans who participated in the 2002 follow-up examination of AFHS.

EXPOSURES

Agent Orange and TCDD. Serum TCDD levels were measured in 1987, 1992, 1997, and 2002.

MAIN OUTCOMES AND MEASURES

Risk of MGUS measured by prevalence, odds ratios (ORs), and 95% CIs.

RESULTS

The 479 Ranch Hand veterans and 479 comparison veterans had similar demographic and lifestyle characteristics and medical histories. The crude prevalence of overall MGUS was 7.1% (34 of 479) in Ranch Hand veterans and 3.1% (15 of 479) in comparison veterans. This translated into a 2.4-fold increased risk for MGUS in Ranch Hand veterans than comparison veterans after adjusting for age, race, BMI in 2002, and the change in BMI between 2002 and the time of blood draw for TCDD measurement (adjusted OR, 2.37; 95% CI, 1.27-4.44; P=.007).

CONCLUSIONS AND RELEVANCE

Operation Ranch Hand veterans have a significantly increased risk of MGUS, supporting an association between Agent Orange exposure and multiple myeloma.

Parkinson's Disease and Pesticides Exposure: New Findings From a Comprehensive Study in Nebraska, USA

BACKGROUND

The association between exposure to agricultural pesticides and Parkinson's Disease (PD) has long been a topic of study in the field of environmental health. This research takes advantage of the unique Nebraska PD registry and state-level crop classification data to investigate the PD-pesticides exposure relationship.

METHODS

First, Geographic Information System and satellite remote sensing data were adopted to calculate exposure to different pesticides for Nebraska residents. An integrated spatial exploratory framework was then adopted to explore the association between PD incidence and exposure to specific pesticide ingredients at the county level.

RESULTS

Our results reveal similarities in geographic patterns of pesticide exposure and PD incidence. The regression analyses indicate that, for most Nebraska counties, PD incidence was significantly associated with exposure to certain pesticide ingredients such as alachlor and broxomy. However, the results also suggest that factors other than pesticide exposure may help further explain the risk of PD at the county level.

CONCLUSIONS

We found significant associations between PD incidence and exposure to different pesticide ingredients. These results have useful implications for PD prevention in Nebraska and other agricultural states in the United States.

Occupational Characteristics and Patterns as Risk Factors for Parkinson's Disease: A Case Control Study

BACKGROUND

Associations have been reported between the risk of Parkinson's disease (PD) and employment in certain fields. Most studies have focused on toxic exposures as potential causal explanations. However, PD also has been associated with personality characteristics that may influence occupational choices and patterns.

OBJECTIVE

This study evaluates the role of personality as indicated by occupational choices and employment patterns in the risk for PD.

METHODS

In-person interviews were conducted to assess occupational histories and early-adult personality indicators among 89 PD patients and 99 controls.

RESULTS

PD cases had fewer lifetime jobs than controls (mean for cases = 4.38 ± 2.20; mean for controls = 5.00 ± 2.26; p = 0.03). Among women, PD was positively associated with more complex work with people (OR = 1.45, 95% CI 1.12-1.89), representing a 95% increased risk for PD comparing women with the greatest complexity of work with those requiring the least complexity of work with people. Women PD cases also performed less complex work with things compared with controls (OR = 0.69 (95% CI 0.53-0.90)), translating into a 13-fold increased risk for PD among women whose work involved the least complex work with things compared with the most. The numbers of jobs and job types were associated with taking more activity risks as a young-adult (r = 0.19, p = 0.02; r = 0.26, p = 0.001, respectively).

CONCLUSIONS

Cases with PD held fewer lifetime jobs compared with controls. Occupational complexity was associated with the risk for PD among women, but not men. Further consideration of the possible influence of personality on occupational choices is warranted.

Overview of the National Occupational Mortality Surveillance (NOMS) system: leukemia and acute myocardial infarction risk by industry and occupation in 30 US states 1985-1999, 2003-2004, and 2007

BACKGROUND

Cancer and chronic disease are leading causes of death in the US with an estimated cost of $46 billion.

METHODS

We analyzed 11 million cause-specific deaths of US workers age 18-64 years in 30 states during 1985-1999, 2003-2004, and 2007 by occupation, industry, race, gender, and Hispanic origin.

RESULTS

The highest significantly elevated proportionate leukemia mortality was observed in engineers, protective service, and advertising sales manager occupations and in banks/savings &loans/credit agencies, public safety, and public administration industries. The highest significantly elevated smoking-adjusted acute myocardial infarction mortality was noted in industrial and refractory machinery mechanics, farmers, mining machine operators, and agricultural worker occupations; and wholesale farm supplies, agricultural chemical, synthetic rubber, and agricultural crop industries.

CONCLUSIONS

Significantly elevated risks for acute myocardial infarction and leukemia were observed across several occupations and industries that confirm existing reports and add new information. Interested investigators can access the NOMS website at http://www.cdc.gov/niosh/topics/NOMS/.

Gender in occupational health research of farmworkers: a systematic review

Background

Farmwork is one of the most hazardous occupations for men and women. Research suggests sex/gender shapes hazardous workplace exposures and outcomes for farmworkers. This paper reviews the occupational health literature on farmworkers, assessing how gender is treated and interpreted in exposure-outcome studies.

Methods

The paper evaluates peer-reviewed articles on men and women farmworkers' health published between 2000 and 2012 in PubMed or SCOPUS. Articles were identified and analyzed for approaches toward sampling, data analysis, and use of exposure indicators in relation to sex/gender.

Results

18% of articles reported on and interpreted sex/gender differences in health outcomes and exposures. Sex/gender dynamics often shaped health outcomes, yet adequate data was not collected on established sex/gender risk factors relating to study outcomes.

Conclusion

Research can better incorporate sex/gender analysis into design, analytical and interpretive approaches to better explore its mediation of health outcomes in light of emerging calls to mainstream gender research. Am. J. Ind. Med. 57:1344–1367, 2014. © 2014 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

A review of prostate cancer incidence and mortality studies of farmers and non-farmers, 2002-2013

OBJECTIVES

To review the recent literature on the incidence and mortality of prostate cancer in farmers compared to non-farmers.

METHODS

Searches were conducted in seven electronic databases for observational studies published from 2002 to 2013. Studies were assessed against eligibility criteria and a narrative summary of findings presented.

RESULTS

Eighteen primary research articles were included in the review. Four of ten mortality studies and two of nine incidence studies reported statistically significant increases in prostate cancer risk in farmers. However, nearly half of all studies reported non-significant reductions in farmers' risk. Additionally, one study reported significantly increased and decreased risk using different outcome measures. Results varied considerably by geographic region, study design and degree of control for confounders, affecting comparability and strength of findings.

CONCLUSIONS

The overall evidence for increased prostate cancer risk in farmers was weak.

Cancer incidence in California farm workers, 1988-2010

BACKGROUND

Farmers and farm workers have previously been found to experience decreased risk of some causes of death but elevated risks of certain types of cancer. A previous report on cancer incidence in a farm worker labor union between 1987 and 1997 found increased leukemia, brain, stomach, and uterine cervix cancer rates in this working population.

METHODS

A roster of farm workers was created and electronically linked to the database of the California Cancer Registry. Proportionate cancer incidence (PCIR), stage, and age at diagnosis and histological subtypes of cancer were compared between the United Farm Workers (UFW) members and the Hispanic population of California as well as to the non-Hispanic whites (NHW).

RESULTS

In this population of 139,000 farm workers in California, more than 3,600 cancer diagnoses were recorded between 1988 and 2010. Proportionately more cancer was noted in the UFW than among California NHW for kidney and renal pelvis cancer (PCIR = 1.60), liver (PCIR = 4.24), prostate (PCIR = 1.13), and uterine cervix cancer (PCIR = 2.08). Proportionately less breast (PCIR = 0.85), lung (PCIR = 0.75), skin melanoma (PCIR = 0.18), and urinary bladder cancer (PCIR = 0.59) was found. Stage at diagnosis was more advanced in the farm workers for several cancer sites, although, not for colorectal cancer.

CONCLUSIONS

These farm workers experience proportionally more prostate, kidney and renal pelvis, brain, liver, stomach, cervix and leukemia and less breast, melanoma, and colorectal cancer than reference populations. For many sites, cancer is not diagnosed as early in the farm workers as in the comparison groups, except for colorectal cancer in females and melanoma in males.

Parkinson's disease and occupation: differences in associations by case identification method suggest referral bias

METHODS

We used a population-based sample of 403 Parkinson's disease cases and 405 controls to examine risks by occupation. Results were compared to a previous clinic-based analysis.

RESULTS

With censoring of jobs held within 10 years of diagnosis, the following had significantly or strongly increased risks: social science, law and library jobs (OR = 1.8); farming and horticulture jobs (OR = 2.0); gas station jobs (OR = 2.6); and welders (OR = 3.0). The following had significantly decreased risks: management and administration jobs (OR = 0.70); and other health care jobs (OR = 0.44).

CONCLUSIONS

These results were consistent with other findings for social science and farming occupations. Risks for teaching, medicine and health occupations were not elevated, unlike our previous clinic-based study. This underscores the value of population-based over clinic-based samples. Occupational studies may be particularly susceptible to referral bias because social networks may spread preferentially via jobs.

Suicide by occupation: systematic review and meta-analysis

BACKGROUND

Previous research has shown that those employed in certain occupations, such as doctors and farmers, have an elevated risk of suicide, yet little research has sought to synthesise these findings across working-age populations.

AIMS

To summarise published research in this area through systematic review and meta-analysis.

METHOD

Random effects meta-analyses were used to calculate a pooled risk of suicide across occupational skill-level groups.

RESULTS

Thirty-four studies were included in the meta-analysis. Elementary professions (e.g. labourers and cleaners) were at elevated risk compared with the working-age population (rate ratio (RR) = 1.84, 95% CI 1.46-2.33), followed by machine operators and deck crew (RR = 1.78, 95% CI 1.22-2.60) and agricultural workers (RR = 1.64, 95% CI 1.19-2.28). Results suggested a stepwise gradient in risk, with the lowest skilled occupations being at greater risk of suicide than the highest skill-level group.

CONCLUSIONS

This is the first comprehensive meta-analytical review of suicide and occupation. There is a need for future studies to investigate explanations for the observed skill-level differences, particularly in people employed in lower skill-level groups.

Significantly higher frequency of Helicobacter suis in patients with idiopathic parkinsonism than in control patients

BACKGROUND

There is increased proportional mortality from Parkinson's disease amongst livestock farmers. The hypokinesia of Parkinson's disease has been linked to Helicobacter pylori. H. suis is the most common zoonotic helicobacter in man.

AIM

To compare the frequency of H. suis, relative to H. pylori, in gastric biopsies of patients with idiopathic parkinsonism (IP) and controls from gastroenterology services.

METHODS

DNA extracts, archived at a Helicobacter Reference Laboratory, from IP patient and gastroenterology service biopsies were examined anonymously for H. suis, using species-specific RT-PCR.

RESULTS

Relative risk of having H. suis in 60 IP patients compared with 256 controls was 10 times greater than that of having H. pylori. In patients with IP and controls, respectively, frequencies of H. suis were 27 (exact binomial 95% C.I. 15, 38) and 2 (0, 3)%, and of H. pylori, 28 (17, 40) and 16 (12, 21)%. Excess of H. suis in IP held when only the antral or corporal biopsy was considered. Of 16 IP patients with H. suis, 11 were from 19 with proven H. pylori eradication, 3 from 17 pre-H. pylori eradication, 2 from 24 H. pylori culture/PCR-negative. Frequency was different between groups (P = 0.001), greatest where H. pylori had been eradicated. Even without known exposure to anti-H. pylori therapy, H. suis was more frequent in IP patients (5/41) than in controls (1/155) (P = 0.002). Partial multilocus sequence typing confirmed that strains from IP patients (6) and control (1) differed from RT-PCR standard strain.

CONCLUSIONS

Greater frequency of H. suis in idiopathic parkinsonism appears exaggerated following H. pylori eradication. Multilocus sequence testing comparison with porcine strains may clarify whether transmission is from pigs/porcine products or of human-adapted, H. suis-like, bacteria.

Occupational exposures and mortality from cardiovascular disease among women textile workers in Shanghai, China

BACKGROUND

Exposure to textile fiber dusts, like particulate air pollution, may be associated with cardiovascular disease (CVD) mortality. Bacterial endotoxin, a potent inflammagen found in cotton dust, may be a specific risk factor.

METHODS

Female textile workers (N = 267,400) in Shanghai, China were followed for CVD mortality (1989-2000). Factory exposures were approximated by sector classifications based on materials and processes. Quantitative endotoxin and cotton dust measures were available for a subcohort (n = 3,188). Cox proportional hazards modeling was used to estimate hazard ratios (HR) and 95% confidence interval (CI).

RESULTS

Slightly elevated mortality risk for the cotton sector was seen for ischemic stroke (HR = 1.12, 95% CI: 0.97-1.31) and hemorrhagic stroke (HR = 1.12, 95% CI: 1.02-1.23). Similar hemorrhagic stroke mortality risk was observed in high dust sectors (HR = 1.12, 95% CI: 1.02-1.24). No association was observed for ischemic heart disease.

CONCLUSIONS

Exposures in textile factories may have contributed to CVD mortality among this cohort. The specific components of these exposures that may be harmful are not clear and should be further investigated.

Leukocyte-subset counts in idiopathic parkinsonism provide clues to a pathogenic pathway involving small intestinal bacterial overgrowth. A surveillance study

BACKGROUND

Following Helicobacter pylori eradication in idiopathic parkinsonism (IP), hypokinesia improved but flexor-rigidity increased. Small intestinal bacterial-overgrowth (SIBO) is a candidate driver of the rigidity: hydrogen-breath-test-positivity is common in IP and case histories suggest that Helicobacter keeps SIBO at bay.

METHODS

In a surveillance study, we explore relationships of IP-facets to peripheral immune/inflammatory-activation, in light of presence/absence of Helicobacter infection (urea-breath- and/or stool-antigen-test: positivity confirmed by gastric-biopsy) and hydrogen-breath-test status for SIBO (positivity: >20 ppm increment, 2 consecutive 15-min readings, within 2h of 25G lactulose). We question whether any relationships found between facets and blood leukocyte subset counts stand in patients free from anti-parkinsonian drugs, and are robust enough to defy fluctuations in performance consequent on short t½ therapy.

RESULTS

Of 51 IP-probands, 36 had current or past Helicobacter infection on entry, 25 having undergone successful eradication (median 3.4 years before). Thirty-four were hydrogen-breath-test-positive initially, 42 at sometime (343 tests) during surveillance (2.8 years). Hydrogen-breath-test-positivity was associated inversely with Helicobacter-positivity (OR 0.20 (95% CI 0.04, 0.99), p<0.05).In 38 patients (untreated (17) or on stable long-t½ IP-medication), the higher the natural-killer count, the shorter stride, slower gait and greater flexor-rigidity (by mean 49 (14, 85) mm, 54 (3, 104) mm.s-1, 89 (2, 177) Nm.10-3, per 100 cells.μl-1 increment, p=0.007, 0.04 & 0.04 respectively, adjusted for patient characteristics). T-helper count was inversely associated with flexor-rigidity before (p=0.01) and after adjustment for natural-killer count (-36(-63, -10) Nm.10-3 per 100 cells.μl-1, p=0.007). Neutrophil count was inversely associated with tremor (visual analogue scale, p=0.01). Effect-sizes were independent of IP-medication, and not masked by including 13 patients receiving levodopa (except natural-killer count on flexor-rigidity). Cellular associations held after allowing for potentially confounding effect of hydrogen-breath-test or Helicobacter status. Moreover, additional reduction in stride and speed (68 (24, 112) mm & 103 (38, 168) mm.s-1, each p=0.002) was seen with Helicobacter-positivity. Hydrogen-breath-test-positivity, itself, was associated with higher natural-killer and T-helper counts, lower neutrophils (p=0.005, 0.02 & 0.008).

CONCLUSION

We propose a rigidity-associated subordinate pathway, flagged by a higher natural-killer count, tempered by a higher T-helper, against which Helicobacter protects by keeping SIBO at bay.

Suicide and pesticide use among pesticide applicators and their spouses in the agricultural health study

BACKGROUND

An association may exist between pesticide exposure and suicide.

OBJECTIVE

We sought to evaluate the existence of an association between pesticide use and suicide using data from the Agricultural Health Study (AHS), a prospective cohort study of licensed pesticide applicators and their spouses in Iowa and North Carolina.

METHODS

Via linkage to state mortality files and the National Death Index, we identified 110 suicides occurring between enrollment in the AHS (from 1993 to 1997) and 31 May 2009, among 81,998 cohort members contributing 1,092,943 person-years of follow-up. The average length of follow-up was 13.3 years. AHS participants provided data on pesticide use and potential confounders via self-administered questionnaires at enrollment. We evaluated several measures of pesticide use: use of any pesticide, ever use of 50 specific pesticides, cumulative lifetime days of use and intensity-adjusted cumulative lifetime days of use of 22 specific pesticides, and ever use of 10 functional and chemical classes of pesticides. We used Cox proportional hazards regression models to estimate adjusted hazard ratios and 95% confidence intervals.

RESULTS

After adjusting for age at enrollment, sex, number of children in family, frequency of alcohol consumption during the past 12 months, and smoking status, we found no association between prior pesticide use and suicide in applicators and their spouses. Results were the same for applicators and spouses together or for applicators alone and were consistent across several measures of pesticide use.

CONCLUSIONS

Our findings do not support an association between moderate pesticide use and suicide.

Epidemiology and etiology of Parkinson's disease: a review of the evidence

The etiology of Parkinson's disease (PD) is not well understood but likely to involve both genetic and environmental factors. Incidence and prevalence estimates vary to a large extent-at least partly due to methodological differences between studies-but are consistently higher in men than in women. Several genes that cause familial as well as sporadic PD have been identified and familial aggregation studies support a genetic component. Despite a vast literature on lifestyle and environmental possible risk or protection factors, consistent findings are few. There is compelling evidence for protective effects of smoking and coffee, but the biologic mechanisms for these possibly causal relations are poorly understood. Uric acid also seems to be associated with lower PD risk. Evidence that one or several pesticides increase PD risk is suggestive but further research is needed to identify specific compounds that may play a causal role. Evidence is limited on the role of metals, other chemicals and magnetic fields. Important methodological limitations include crude classification of exposure, low frequency and intensity of exposure, inadequate sample size, potential for confounding, retrospective study designs and lack of consistent diagnostic criteria for PD. Studies that assessed possible shared etiological components between PD and other diseases show that REM sleep behavior disorder and mental illness increase PD risk and that PD patients have lower cancer risk, but methodological concerns exist. Future epidemiologic studies of PD should be large, include detailed quantifications of exposure, and collect information on environmental exposures as well as genetic polymorphisms.

Insecticide use and risk of rheumatoid arthritis and systemic lupus erythematosus in the Women's Health Initiative Observational Study

OBJECTIVE

Farming and agricultural pesticide use has been associated with 2 autoimmune rheumatic diseases, rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). However, risk associated with other residential or work place insecticide use is unknown.

METHODS

We analyzed data from the Women's Health Initiative Observational Study (n=76,861 postmenopausal women, ages 50-79 years). Incident cases (n=213: 178 for RA, 27 for SLE, and 8 for both) were identified based on self-report and use of disease-modifying antirheumatic drugs at year 3 of followup. We examined self-reported residential or work place insecticide use (personally mixing/applying by self and application by others) in relation to RA/SLE risk, overall and in relation to farm history. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were adjusted for age, race, region, education, occupation, smoking, reproductive factors, asthma, other autoimmune diseases, and comorbidities.

RESULTS

Compared with never used, personal use of insecticides was associated with increased RA/SLE risk, with significant trends for greater frequency (HR 2.04, 95% CI 1.17-3.56 for ≥6 times/year) and duration (HR 1.97, 95% CI 1.20-3.23 for ≥20 years). Risk was also associated with long-term insecticide application by others (HR 1.85, 95% CI 1.07-3.20 for ≥20 years) and frequent application by others among women with a farm history (HR 2.73, 95% CI 1.10-6.78 for ≥6 times/year).

CONCLUSION

These results suggest residential and work place insecticide exposure is associated with the risk of autoimmune rheumatic diseases in postmenopausal women. Although these findings require replication in other populations, they support a role for environmental pesticide exposure in the development of autoimmune rheumatic diseases.

Mortality in the agricultural health study, 1993-2007

Comparing agricultural cohorts with the general population is challenging because the general healthiness of farmers may mask potential adverse health effects of farming. Using data from the Agricultural Health Study, a cohort of 89,656 pesticide applicators and their spouses (N = 89, 656) in North Carolina and Iowa, the authors computed standardized mortality ratios (SMRs) comparing deaths from time of the enrollment (1993-1997) through 2007 to state-specific rates. To compensate for the cohort's overall healthiness, relative SMRs were estimated by calculating the SMR for each cause relative to the SMR for all other causes. In 1,198,129 person-years of follow-up, 6,419 deaths were observed. The all-cause mortality rate was less than expected (SMR(applicators) = 0.54, 95% confidence interval (CI): 0.52, 0.55; SMR(spouses) = 0.52, 95% CI: 0.50, 0.55). SMRs for all cancers, heart disease, and diabetes were significantly below 1.0. In contrast, applicators experienced elevated numbers of machine-related deaths (SMR = 4.15, 95% CI: 3.18, 5.31), motor vehicle nontraffic accidents (SMR = 2.80, 95% CI: 1.81, 4.14), and collisions with objects (SMR = 2.12, 95% CI: 1.25, 3.34). In the relative SMR analysis for applicators, the relative mortality ratio was elevated for lymphohematopoietic cancers, melanoma, and digestive system, prostate, kidney, and brain cancers. Among spouses, relative SMRs exceeded 1.0 for lymphohematopoietic cancers and malignancies of the digestive system, brain, breast, and ovary. Unintentional fatal injuries remain an important risk for farmers; mortality ratios from several cancers were elevated relative to other causes.

Endotoxin and cancer

Exposure to endotoxin, a component of gram-negative bacterial cell walls, is widespread in many industrial settings and in the ambient environment. Heavy-exposure environments include livestock farms, cotton textile facilities, and saw mills. In this article, we review epidemiologic, clinical trial, and experimental studies pertinent to the hypothesis that endotoxin prevents cancer. Since the 1970s, epidemiologic studies of cotton textile and other endotoxin-exposed occupational groups have consistently demonstrated reduced lung cancer risks. Experimental animal toxicology research and some limited therapeutic trials in cancer patients offer additional support for an anticarcinogenic potential. The underlying biological mechanisms of anticarcinogenesis are not entirely understood but are thought to involve the recruitment and activation of immune cells and proinflammatory mediators (e.g., tumor necrosis factor α and interleukin-1 and -6). In view of the current state of knowledge, it would be premature to recommend endotoxin as a cancer-chemopreventive agent. However, further epidemiologic and experimental investigations that can clarify further dose-effect and exposure-timing relations could have substantial public health and basic biomedical benefits.

Pesticide use and myocardial infarction incidence among farm women in the agricultural health study

OBJECTIVE

To evaluate the relationship between pesticide use and myocardial infarction (MI) among farm women.

BACKGROUND

Little is known about the potential association between pesticide use and cardiovascular outcomes.

METHODS

We used logistic regression to evaluate pesticide use and self-reported incident nonfatal MI among women in the Agricultural Health Study.

RESULTS

Of those MI-free at enrollment (n = 22,425), 168 reported an MI after enrollment. We saw no association with pesticide use overall. Six of 27 individual pesticides evaluated were significantly associated with nonfatal MI, including chlorpyrifos, coumaphos, carbofuran, metalaxyl, pendimethalin, and trifluralin, which all had odds ratios >1.7. These chemicals were used by <10% of the cases, and their use was correlated, making it difficult to attribute the risk elevation to a specific pesticide.

CONCLUSION

Pesticides may contribute to MI risk among farm women.

Suicide in selected occupations in Queensland: evidence from the State suicide register

OBJECTIVE

Prior research has suggested an association between suicide and certain occupations. The aim of the present study was to report on suicide rates in selected occupations in Queensland (QLD).

METHOD

Suicide mortality data from the QLD Suicide Register and population data from the Australian Bureau of Statistics were obtained for the period 1990-2006. Suicide rates were calculated for each occupational group and compared to rates within the general population (15-64 year age group) and the employed population of QLD.

RESULTS

There was significantly higher risk of suicide for male subjects in the agricultural, transport and construction sectors of QLD. High suicide rates were also found in female nurses, artists, agricultural workers and cleaners, while education professionals (of both genders) appeared at lower risk.

CONCLUSIONS

The significantly higher suicide rates for employees of the agriculture, construction, and transport industries indicate a need for further research into the occupation-specific conditions and individual or other social-environmental factors that may accentuate suicide risk within these professions. Use of higher quality occupational data is also warranted in future studies.

Endotoxin and cancer

OBJECTIVE

Exposure to endotoxin, a component of gram-negative bacterial cell walls, is widespread in many industrial settings and in the ambient environment. Heavy-exposure environments include livestock farms, cotton textile facilities, and saw mills. Concentrations are highly variable in non-occupational indoor and outdoor environments. Endotoxin is a potent inflammagen with recognized health effects, including fever, shaking chills, septic shock, toxic pneumonitis, and respiratory symptoms. Somewhat paradoxically, given the putative role of inflammation in carcinogenesis, various lines of evidence suggest that endotoxin may prevent cancer initiation or limit tumor growth. The hypothesis that components of bacteria may retard cancer progression dates back to William B. Coley's therapeutic experiments ("bacterial vaccine") in the 1890s.

DATA SOURCES

In this article, we review epidemiologic, clinical trial, and experimental studies pertinent to the hypothesis that endotoxin prevents cancer. Since the 1970s, epidemiologic studies of cotton textile and other endotoxin-exposed occupational groups have consistently demonstrated reduced lung cancer risks. Experimental animal toxicology research and some limited therapeutic trials in cancer patients offer additional support for an anticarcinogenic potential. The underlying biological mechanisms of anticarcinogenesis are not entirely understood but are thought to involve the recruitment and activation of immune cells and proinflammatory mediators (e.g., tumor necrosis factor alpha and interleukin-1 and -6).

CONCLUSIONS

In view of the current state of knowledge, it would be premature to recommend endotoxin as a cancer-chemopreventive agent. Nonetheless, further epidemiologic and experimental investigations that can clarify further dose-effect and exposure-timing relations could have substantial public health and basic biomedical benefits.

Pesticide exposure and risk of monoclonal gammopathy of undetermined significance in the Agricultural Health Study

Pesticides are associated with excess risk of multiple myeloma, albeit inconclusively. We included 678 men (30-94 years) from a well-characterized prospective cohort of restricted-use pesticide applicators to assess the risk of monoclonal gammopathy of undetermined significance (MGUS). Serum samples from all subjects were analyzed by electrophoresis performed on agarose gel; samples with a discrete or localized band were subjected to immunofixation. Age-adjusted prevalence estimates of MGUS were compared with MGUS prevalence in 9469 men from Minnesota. Associations between pesticide exposures and MGUS prevalence were assessed by logistic regression models adjusted for age and education level. Among study participants older than 50 years (n = 555), 38 were found to have MGUS, yielding a prevalence of 6.8% (95% CI, 5.0%-9.3%). Compared with men from Minnesota, the age-adjusted prevalence of MGUS was 1.9-fold (95% CI, 1.3- to 2.7-fold) higher among male pesticide applicators. Among applicators, a 5.6-fold (95% CI, 1.9- to 16.6-fold), 3.9-fold (95% CI, 1.5- to 10.0-fold), and 2.4-fold (95% CI, 1.1- to 5.3-fold) increased risk of MGUS prevalence was observed among users of the chlorinated insecticide dieldrin, the fumigant mixture carbon-tetrachloride/carbon disulfide, and the fungicide chlorothalonil, respectively. In summary, the prevalence of MGUS among pesticide applicators was twice that in a population-based sample of men from Minnesota, adding support to the hypothesis that specific pesticides are causatively linked to myelomagenesis.

Multiple myeloma and farming. A systematic review of 30 years of research. Where next?

Background

Multiple myeloma has been linked to farming for over thirty years. However, there is little clarity about the magnitude of the risk, nor about the specific agricultural exposures which contribute to the risk.

Methods

We have carried out a systematic review of case-control studies of multiple myeloma published from 1970 to October 2007. Studies were identified through database searches and from references in the literature.

Studies reporting risk estimates from farming, agricultural exposures, and exposure to animals were identified, and details abstracted. The impact of study heterogeneity, publication bias, variation in methods of case identification and exposure ascertainment between studies were considered in analysis.

Results

Case control studies showed a pooled odds ratio (OR) for working as a farmer of 1.39 95% CI 1.18 to 1.65. There was no graphic evidence of publication bias, for pesticide exposure 1.47; 95% 1.11 to 1.94, for DDT 2.19; CI 95% 1.30 to 2.95; for exposed to herbicides 1.69; 95 %CI 1.01 to 1.83. For working on a farm for more than ten years OR was 1.87; 95% CI 1.15 to 3.16.

Conclusion

Farmers seem to have increase risk for MM. However, a major limitation of this analysis is the presence of significant heterogeneity across the studies and the evidence of publication bias in some models.

A pooled analysis using individual level data could provide more power and permit the harmonization of occupational and exposure coding data.

Domestic and farm-animal exposures and risk of non-Hodgkin's lymphoma in a population-based study in the San Francisco Bay Area

OBJECTIVE

To assess the association between animal exposures and non-Hodgkin's lymphoma (NHL).

METHODS

Exposure data were collected from 1,591 cases and 2,515 controls during in-person interviews in a population-based case-control study of NHL in the San Francisco Bay Area. Odds ratios (OR) and 95% confidence intervals (95% CI) were adjusted for potential confounders.

RESULTS

Pet owners had a reduced risk of NHL (OR, 0.71; 95% CI, 0.52-0.97) and diffuse large-cell lymphoma large cell (DLCL; OR, 0.58; 95% CI, 0.39-0.87) compared with those who never had owned a pet. Ever having owned dogs and/or cats was associated with reduced risk of all NHL (OR, 0.71; 95% CI, 0.54-0.94) and of DLCL (OR, 0.60; 95% CI, 0.42-0.86). Longer duration of cat ownership (P(trend) = 0.008), dog ownership (P(trend) = 0.04), and dog and/or cat ownership (P(trend) = 0.004) was inversely associated with risk of NHL. Ownership of pets other than cats and dogs was associated with a reduced risk of NHL (OR, 0.64; 95% CI, 0.55-0.74) and DLCL (OR, 0.58; 95% CI, 0.47-0.71). Exposure to cattle for >or=5 years was associated with an increased risk of NHL (OR, 1.6; 95% CI, 1.0-2.5) as was exposure to pigs for all NHL (OR, 1.8; 95% CI, 1.2-2.6) and for DLCL (OR, 2.0; 95% CI, 1.2-3.4).

CONCLUSIONS

The association between animal exposure and NHL warrants further investigation in pooled analyses.

Ethnic, racial, and gender variations in health among farm operators in the United States

PURPOSE

The purpose of this study was to collect baseline prevalence data on the health problems faced by minority, white, and female farm operators.

METHODS

An occupational health survey of farm operators was conducted by the U.S. Department of Agriculture, National Agricultural Statistics Service between February and August 2000. A stratified random sample of farm operators from 50 U.S. states based on the 1997 Census of Agriculture was selected for telephone interview. Interviews were primarily conducted using a computer assisted telephone instrument system.

RESULTS

Population prevalences were calculated for 7137 farm operators. Prevalences were greatest for musculoskeletal discomfort, followed by respiratory problems, hearing loss, and hypertension. Generally, Latino and Asian American operators had lower prevalences for health problems than white non-Latino and white operators, respectively. African-American operators had greater prevalences for hypertension, and osteoarthritis, but lower prevalences for hearing loss, skin problems, heart problems, and cancer than white operators. American Indian or Alaska Native operators had higher prevalences for musculoskeletal problems, skin problems, and hypertension.

CONCLUSIONS

Prevalences for the different ethnicity and race groups are not the same. Studies that combine racial and ethnic groups, or study only white and non-Latino farm operators may overestimate or underestimate the prevalence of health conditions in the entire farm operator population.

Cancer mortality and farming in South Korea: an ecologic study

OBJECTIVE

The aim of this study was to examine the geographical difference of cancer mortality to determine any potential associations between cancer mortality and farming in South Korea.

METHODS

We calculated standardized mortality ratios (SMRs) based on age- and gender-specific cancer mortality rates for 245 geographic areas, using the registered death data from 2000 to 2004 that were obtained from the Korea National Statistical Office. Using the data from the Agriculture Census in 1995, we obtained the farming index. Poisson regression analysis was used to evaluate the associations between cancer mortality and farming after adjustment for socioeconomic factors.

RESULTS

The SMR analyses based on 62,403 annual average cancer deaths yielded regional variations for all cancers combined in men (SMR = 70-192) and women (SMR = 80-132). With increasing farming index we found significantly elevated cancer mortality of esophagus, stomach, brain, and leukemia for men, and of esophagus and stomach for women, whereas the SMR for colorectal and gall bladder cancers were inversely associated with farming. The results were similar when the analyses were repeated after the exclusion of metropolitan areas.

CONCLUSIONS

Our findings suggest a possible association between farming and mortality from a few cancer sites in South Korea.

Carcinogenicity of agricultural pesticides in adults and children

The role of specific agricultural pesticides in relation to adult and childhood cancers has not been firmly established due to the lack of precise exposure data in previous studies. Improvements in exposure assessment, disease classification, and application of molecular techniques in recent epidemiological evaluations is rapidly improving our ability to evaluate the human carcinogenicity of agricultural pesticides. The role of pesticide exposures in the etiology of human cancer is outlined by anatomical site and recent development in exposure assessment and molecular epidemiology are summarized and evaluated.

A population-based job exposure matrix for power-frequency magnetic fields

A population-based job exposure matrix (JEM) was developed to assess personal exposures to power-frequency magnetic fields (MF) for epidemiologic studies. The JEM compiled 2,317 MF measurements taken on or near workers by 10 studies in the United States, Sweden, New Zealand, Finland, and Italy. A database was assembled from the original data for six studies plus summary statistics grouped by occupation from four other published studies. The job descriptions were coded into the 1980 Standard Occupational Classification system (SOC) and then translated to the 1980 job categories of the U.S. Bureau of the Census (BOC). For each job category, the JEM database calculated the arithmetic mean, standard deviation, geometric mean, and geometric standard deviation of the workday-average MF magnitude from the combined data. Analysis of variance demonstrated that the combining of MF data from the different sources was justified, and that the homogeneity of MF exposures in the SOC occupations was comparable to JEMs for solvents and particulates. BOC occupation accounted for 30% of the MF variance (p << 10(-6)), and the contrast (ratio of the between-job variance to the total of within- and between-job variances) was 88%. Jobs lacking data had their exposures inferred from measurements on similar occupations. The JEM provided MF exposures for 97% of the person-months in a population-based case-control study and 95% of the jobs on death certificates in a registry study covering 22 states. Therefore, we expect this JEM to be useful in other population-based epidemiologic studies.

Chronic lymphocytic leukemia radiogenicity: a systematic review

OBJECTIVE

Chronic lymphocytic leukemia (CLL) is generally considered to be non-radiogenic and is excluded from several programs that compensate workers for illnesses resulting from occupational exposures. Questions about whether this exclusion is justified prompted a Congressional mandate to the National Institute for Occupational Safety and Health (NIOSH) to, further, examine the radiogenicity of CLL. This study revisits the question of CLL radiogenicity by examining epidemiologic evidence from occupationally and medically-exposed populations.

METHODS

A systematic review of radiation-exposed cohorts was conducted to investigate the association between radiation and CLL. Exploratory power calculations for a pooled occupational study were performed to examine the feasibility of assessing CLL radiogenicity epidemiologically.

RESULTS

There is a bias against reporting CLL results, because of the disease's presumed non-radiogenicity. In medical cohort studies that provide risk estimates for CLL, risk is elevated, though non-significantly, in almost all studies with more than 15 years average follow-up. The results of occupational studies are less consistent.

CONCLUSIONS

Studies with adequate follow-up time and power are needed to better understand CLL radiogenicity. Power analyses show that a pooled study might detect risk on the order of radiation induced non-CLL leukemia, but is unlikely to detect smaller risks.

Occupation and the risk of non-Hodgkin lymphoma

Although thus far no occupational agents have been classified as established causes of non-Hodgkin lymphoma (NHL), employment as a farmer, teacher, dry cleaner, meat worker, printer, or wood worker has been associated with elevated risk in the peer-reviewed literature. We conducted several meta-analyses to assess risk in these occupations and industries from articles published in MEDLINE up to August 1, 2006. The summary risk estimates suggest a homogeneous excess risk for NHL among workers in the printing industry [relative risk (RR), 1.86; 95% confidence interval (95% CI), 1.37-2.52] and wood workers (RR, 1.15; 95% CI, 1.00-1.31). Considerable heterogeneity but elevated risks were found for farmers (RR, 1.11; 95% CI, 1.05-1.17), especially in animal husbandry (RR, 1.31; 95% CI, 1.08-1.60), and teaching (RR, 1.47; 95% CI, 1.34-1.61). An increased risk was absent for employment in the meat processing industry (RR, 0.99; 95% CI, 0.77-1.29). These results suggest that although excess risk is found for employment in the printing industry, wood processing industry, teaching, and farming, it is unlikely that occupation represents a major risk factor for NHL in most populations. At present, no conclusive evidence of causal relations between occupations and increased NHL risk exists; this can be ascribed to methodologic problems in studying the link between NHL risk and occupation, including heterogeneity of disease and exposure circumstances and low statistical power. Implementing state-of-the-art exposure assessment technologies, including biomarker-based assessment, and aiming to identify susceptible subgroups can increase the statistical power enough to analyze etiologically relevant NHL subtypes and provide clues on possible causal agents in future studies. These goals can be best attained within the framework of large-scale, international collaborative projects.

Mortality among pesticide applicators exposed to chlorpyrifos in the Agricultural Health Study

BACKGROUND

Chlorpyrifos is one of the most widely used organophosphate insecticides in the United States. Although the toxicity of chlorpyrifos has been extensively studied in animals, the epidemiologic data are limited.

OBJECTIVE

To evaluate whether agricultural chlorpyrifos exposure was associated with mortality, we examined deaths among pesticide applicators in the Agricultural Health Study, a prospective study of licensed pesticide applicators in Iowa and North Carolina.

METHODS

A total of 55,071 pesticide applicators were included in this analysis. Detailed pesticide exposure data and other information were obtained from self-administered questionnaires completed at the time of enrollment (1993-1997). Lifetime chlorpyrifos use was divided into tertiles. Poisson regression analysis was used to evaluate the exposure-response relationships between chlorpyrifos use and causes of death after adjustment for potential confounders.

RESULTS

A total of 1,851 deaths (588 among chlorpyrifos users) were observed during the study period, 1993-2001. The relative risk (RR) of death from all causes combined among applicators exposed to chlorpyrifos was slightly lower than that for nonexposed applicators (RR = 0.90; 95% confidence interval, 0.81-1.01). For most causes of death analyzed, there was no evidence of an exposure-response relationship. However, the relative risks for mortality from suicide and non-motor-vehicle accidents were increased 2-fold in the highest category of chlorpyrifos exposure days.

CONCLUSIONS

Our findings of a possible association between chlorpyrifos use and external causes of death were based on small numbers. However, the findings may reflect a link between chlorpyrifos and depression or other neurobehavioral symptoms that deserves further evaluation.

Multiple myeloma: A review of the epidemiologic literature

Multiple myeloma, a neoplasm of plasma cells, accounts for approximately approximately 15% of lymphatohematopoietic cancers (LHC) and 2% of all cancers in the US. Incidence rates increase with age, particularly after age 40, and are higher in men, particularly African American men. The etiology is unknown with no established lifestyle, occupational or environmental risk factors. Although several factors have been implicated as potentially etiologic, findings are inconsistent. We reviewed epidemiologic studies that evaluated lifestyle, dietary, occupational and environmental factors; immune function, family history and genetic factors; and the hypothesized precursor, monoclonal gammopathies of undetermined significance (MGUS). Because multiple myeloma is an uncommon disease, etiologic assessments can be difficult because of small numbers of cases in occupational cohort studies, and few subjects reporting exposure to specific agents in case-control studies. Elevated risks have been reported consistently among persons with a positive family history of LHC. A few studies have reported a relationship between obesity and multiple myeloma, and this may be a promising area of research. Factors underlying higher incidence rates of multiple myeloma in African Americans are not understood. The progression from MGUS to multiple myeloma has been reported in several studies; however, there are no established risk factors for MGUS. To improve our understanding of the causes of multiple myeloma, future research efforts should seek the causes of MGUS. More research is also needed on the genetic factors of multiple myeloma, given the strong familial clustering of the disease.