Prevalence of exposure to solvents, metals, grain dust, and other hazards among farmers in the Agricultural Health Study

Association of immunotoxicological indices with lung cancer biomarkers in poultry, grape, and rose farming workers

Exposure to occupational hazards like dust, pesticides, diesel emission particles, or physical hazards in the agricultural sector is known to cause adverse health effects on farm workers. Our study aimed at addressing the association of immunomodulatory status with plasma levels of lung cancer biomarkers in farming population, attempting to recognition of vulnerable farming group. Blood samples from apparently healthy 51 chicken husbandry, 19 grape orchard, and 21 rose greenhouse workers were subjected to evaluate plasma levels of two representative lung cancer biomarkers, pro-gastrin releasing peptide (Pro-GRP) and cytokeratin fragment 19 (CYFRA 21-1). Peripheral blood mononuclear cells obtained from farmers were used for natural killer (NK) cell phenotyping and cytokines (interferon-gamma, IFN-γ and interleukin-13, IL-13) profiling in the culture supernatant. Compared to the rose greenhouse farmers, the grape orchard and chicken husbandry workers revealed a significantly upregulated plasma Pro-GRP and CYFRA 21-1 level. A low proportion of NK cells was observed among the female grape orchard workers and a lowered IFN- γ:IL-13 ratio was seen in the grape and chicken husbandry workers than the rose workers. Our findings imply that grape orchard and chicken husbandry workers have more disturbed immune homeostasis implicated with augmentation in the levels of lung cancer biomarkers than the rose greenhouse workers.

Testicular germ cell tumour risk by occupation and industry: a French case-control study - TESTIS

OBJECTIVE

Testicular germ cell tumours (TGCT) are the most common cancer in men of working age and its incidence has increased notably over the past 40 years. Several occupations have been identified as potentially associated with TGCT risk. The aim of this study was to further explore the relationship between occupations, industries and TGCT risk in men aged 18-45 years.

METHODS

The TESTIS study is a multicenter case-control study conducted between January 2015 and April 2018 in 20 of 23 university hospital centers in metropolitan France. A total of 454 TGCT cases and 670 controls were included. Full job histories were collected. Occupations were coded according to the International Standard Classification of Occupation 1968 version (ISCO-1968) and industry according to the 1999 version of Nomenclature d'Activités Française (NAF-1999). For each job held, ORs and 95% CIs were estimated using conditional logistic regression.

RESULTS

A positive association was observed between TGCT and occupation as agricultural, animal husbandry worker (ISCO: 6-2; OR 1.71; 95% CI (1.02 to 2.82)), as well as salesman (ISCO: 4-51; OR 1.84; 95% CI (1.20 to 2.82)). An increased risk was further observed among electrical fitters and related, electrical and electronics workers employed for 2 years or more (ISCO: 8-5; OR≥2 years 1.83; 95% CI (1.01 to 3.32)). Analyses by industry supported these findings.

CONCLUSIONS

Our findings suggest that agricultural, electrical and electronics workers, and salesmen workers experience an increased risk of TGCT. Further research is needed to identify the agents or chemicals in these high-risk occupations which are relevant in the TGCT development.

TRIAL REGISTRATION NUMBER

NCT02109926.

The occurrence of bone and joint cancers and their association with rural living and radon exposure in Iowa

Primary bone and joint cancers are rare and understudied, yet these neoplasms are difficult to treat and impact all age groups. To explore the long-term changes in the occurrence of bone and joint cancers, patients diagnosed with these neoplasms between 1975 and 2016 were identified in the Surveillance Epidemiology and End Results of the National Cancer Institute of the USA. The age-adjusted incidence (AAIR) and mortality (AAMR) rates were calculated for three decades and compared to AAIR and AAMR in years 1975-1984. By using the population-based cancer registries of the USA, Iowa was identified as a state with increased cases of bone and joint malignancies. The bone and joint cancer cases in Iowa were correlated with the percentage of rural population, the average farmland size, or the residential radon levels. Results demonstrated that the mean AAIR of bone and joint cancers for US female and male patients (< 50 years of age) increased from 0.57 (95% C.I. 0.55-0.63) and 0.76 (95% C.I. 0.69-0.82) for years 1975-1984 to 0.71 (95% C.I. 0.66-0.76) and 0.94 (95% C.I. 0.87-1.07) for years 2005-2014, respectively. The increase in bone and joint cancer cases in Iowa positively correlated with the percentage rural population (R = 0.222, P < 0.02), and the average farmland size (R = 0.236, P < 0.02) but not the radon levels (R = - 0.038, P < 0.7). The findings revealed that patients younger than 50 years of age and those who resided in rural areas and engaged in farming were more likely to be diagnosed with primary bone and joint cancers.

Coexposure to Solvents and Noise as a Risk Factor for Hearing Loss in Agricultural Workers

OBJECTIVE

This study addressed the relationship of hearing loss and coexposure to solvents and noise among farmers and ranchers in central United States.

METHODS

The surveillance study included surveys to stratified random samples of operations in 2018 and 2020 (n = 34,146), requesting information on injuries, illnesses, exposures, and preventive measures. Responses (n = 7495) were analyzed using hierarchical multinomial logistic regression, adjusting for personal and work characteristics.

RESULTS

Nearly 60% of respondents exposed to both solvents and noise reported hearing loss. The exposures increased the adjusted odds of moderate/severe hearing loss as follows: solvents alone, (odds ratio [OR], 1.49; 95% confidence interval [CI], 0.93-2.38), noise alone (OR, 4.42; 95% CI, 3.39-5.76), and coexposure to both noise and solvents (OR, 6.03; 95% CI, 4.67-7.78).

CONCLUSIONS

Solvent exposure, along with noise, should be considered in hearing conservation programs among farmers and ranchers.

Work-related injuries among farm workers engaged in agricultural operations in India: a cross-sectional study

PURPOSE

We aim to investigate nature, risk factors as well as magnitude of farm injuries and fatalities among agricultural workers in rural India.

METHODS

An Agricultural Injury Study (AIS) was conducted using selected 1703 villages in eight states of rural India based on statistical consideration using unstructured proforma for 3086 victims/respodents, who were mostly agricultural workers or farmers. Injury incidence rate (IIR) was estimated per 1000 machines/tools per year for farm machinery and hand tools injuries, and per 100 000 workers per year for other sources. Questions about the injuries involved in farming tasks were used.

RESULTS

About 36.2% fatalities were caused by farm machinery that involves tractors. The IIR per year of farm machinery, hand tools and injuries due to other sources were 3.2 per 1000 machines, 0.7 per 1000 tools and 77 per 100 000 workers, respectively. Correlation between number of injury-prone agricultural machines and number of farm machinery injury is r=0.80 (number of injuries increases with increase in number of machines). The χ²=72.53; p<0.01 of number of hand tools and number of farm hand tools-related injuries, that is, they are statistically significant.

CONCLUSION

Exposures to agricultural machineries during farming operations can result in injuries confounding that may be fatal or non-fatal. Mapping down the cause and taking preventive measure to reduce the losses are of major concern. Also, customised safety programme as well as legislative awareness is needed to be raised for the higher injury incidence group.

Cancer incidence in agricultural workers: Findings from an international consortium of agricultural cohort studies (AGRICOH)

BACKGROUND

Agricultural work can expose workers to potentially hazardous agents including known and suspected carcinogens. This study aimed to evaluate cancer incidence in male and female agricultural workers in an international consortium, AGRICOH, relative to their respective general populations.

METHODS

The analysis included eight cohorts that were linked to their respective cancer registries: France (AGRICAN: n = 128,101), the US (AHS: n = 51,165, MESA: n = 2,177), Norway (CNAP: n = 43,834), Australia (2 cohorts combined, Australian Pesticide Exposed Workers: n = 12,215 and Victorian Grain Farmers: n = 919), Republic of Korea (KMCC: n = 8,432), and Denmark (SUS: n = 1,899). For various cancer sites and all cancers combined, standardized incidence ratios (SIR) and 95% confidence intervals (CIs) were calculated for each cohort using national or regional rates as reference rates and were combined by random-effects meta-analysis.

RESULTS

During nearly 2,800,000 person-years, a total of 23,188 cancers were observed. Elevated risks were observed for melanoma of the skin (number of cohorts = 3, meta-SIR = 1.18, CI: 1.01-1.38) and multiple myeloma (n = 4, meta-SIR = 1.27, CI: 1.04-1.54) in women and prostate cancer (n = 6, meta-SIR = 1.06, CI: 1.01-1.12), compared to the general population. In contrast, a deficit was observed for the incidence of several cancers, including cancers of the bladder, breast (female), colorectum, esophagus, larynx, lung, and pancreas and all cancers combined (n = 7, meta-SIR for all cancers combined = 0.83, 95% CI: 0.77-0.90). The direction of risk was largely consistent across cohorts although we observed large between-cohort variations in SIR for cancers of the liver and lung in men and women, and stomach, colorectum, and skin in men.

CONCLUSION

The results suggest that agricultural workers have a lower risk of various cancers and an elevated risk of prostate cancer, multiple myeloma (female), and melanoma of skin (female) compared to the general population. Those differences and the between-cohort variations may be due to underlying differences in risk factors and warrant further investigation of agricultural exposures.

Incidence, Risk Factors, and Prediction of Myocardial Infarction and Stroke in Farmers: A Korean Nationwide Population-based Study

Objectives

This study was conducted to determine the incidence and risk factors of myocardial infarction (MI) and stroke in farmers compared to the general population and to establish 5-year prediction models.

Methods

The farmer cohort and the control cohort were generated using the customized database of the National Health Insurance Service of Korea database and the National Sample Cohort, respectively. The participants were followed from the day of the index general health examination until the events of MI, stroke, or death (up to 5 years).

Results

In total, 734 744 participants from the farmer cohort and 238 311 from the control cohort aged between 40 and 70 were included. The age-adjusted incidence of MI was 0.766 and 0.585 per 1000 person-years in the farmer and control cohorts, respectively. That of stroke was 0.559 and 0.321 per 1000 person-years in both cohorts, respectively. In farmers, the risk factors for MI included male sex, age, personal history of hypertension, diabetes, current smoking, creatinine, metabolic syndrome components (blood pressure, triglycerides, and high-density lipoprotein cholesterol). Those for stroke included male sex, age, personal history of hypertension, diabetes, current smoking, high γ-glutamyl transferase, and metabolic syndrome components (blood pressure, triglycerides, and high-density lipoprotein cholesterol). The prediction model showed an area under the receiver operating characteristic curve of 0.735 and 0.760 for MI and stroke, respectively, in the farmer cohort.

Conclusions

Farmers had a higher age-adjusted incidence of MI and stroke. They also showed distinct patterns in cardiovascular risk factors compared to the general population.

Diesel Exhaust Exposure during Farming Activities: Statistical Modeling of Continuous Black Carbon Concentrations

OBJECTIVES

Daily driving of diesel-powered tractors has been linked to increased lung cancer risk in farmers, yet few studies have quantified exposure levels to diesel exhaust during tractor driving or during other farm activities. We expanded an earlier task-based descriptive investigation of factors associated with real-time exposure levels to black carbon (BC, a surrogate of diesel exhaust) in Iowa farmers by increasing the sample size, collecting repeated measurements, and applying statistical models adapted to continuous measurements.

METHODS

The expanded study added 43 days of sampling, for a total of 63 sample days conducted in 2015 and 2016 on 31 Iowa farmers. Real-time, continuous monitoring (30-s intervals) of personal BC concentrations was performed using a MicroAeth AE51 microaethelometer affixed with a micro-cyclone. A field researcher recorded information on tasks, fuel type, farmer location, and proximity to burning biomass. We evaluated the influence of these variables on log-transformed BC concentrations using a linear mixed-effect model with random effects for farmer and day and a first-order autoregressive structure for within-day correlation.

RESULTS

Proximity to diesel-powered equipment was observed for 42.5% of the overall sampling time and on 61 of the 63 sample days. Predicted geometric mean BC concentrations were highest during grain bin work, loading, and harvesting, and lower for soil preparation and planting. A 68% increase in BC concentrations was predicted for close proximity to a diesel-powered vehicle, relative to far proximity, while BC concentrations were 44% higher in diesel vehicles with open cabins compared with closed cabins. Task, farmer location, fuel type, and proximity to burning biomass explained 8% of within-day variance in BC concentrations, 2% of between-day variance, and no between-farmer variance.

CONCLUSION

Our findings showed that farmers worked frequently near diesel equipment and that BC concentrations varied between tasks and by fuel type, farmer location, and proximity to burning biomass. These results could support the development of exposure models applicable to investigations of health effects in farmers associated with exposure to diesel engine exhaust.

Carpal Tunnel Syndrome Among Male French Farmers and Agricultural Workers: Is It Only Associated With Physical Exposure?

Background

Exploratory study to investigate whether co-exposure to physical wrist stressors and chemicals is associated with carpal tunnel syndrome (CTS) in French male farmers and agricultural workers.

Methods

Cross-sectional study of 711 men aged 30–65 years and working as either farmers or agricultural workers in 2009–2010 within a cohort covered by the French Agricultural Workers' and Farmers' Mutual Benefit Fund. CTS and exposure to physical wrist stressors and chemicals were assessed using a self-administered questionnaire. Associations between CTS and personal/medical factors, exposure to physical wrist stressors, exposure to chemicals, and co-exposure to physical wrist stressors and chemicals were studied using multivariate logistic regression models.

Results

Forty-four men {5.6% [95% confidence interval (CI) 4.0–7.7]} reported that they had suffered from unilateral/bilateral CTS during the last 12 months. CTS was associated with age, current smoking [odds ratio (OR) = 2.1 (1.0–4.5)], and exposure to physical wrist stressors [OR = 2.6 (1.1–5.9)]. An association was found between CTS and co-exposure to physical wrist stressors and chemicals [OR = 3.3 (0.8–14.3), p = 0.044] in comparison with the no-exposure group.

Conclusions

This exploratory study shows an association of CTS with exposure to biomechanical wrist stressors in male farmers and agricultural workers and suggests an association of CTS with co-exposure to physical wrist stressors and chemicals. Owing to the limitations of the study, this result must be confirmed by a prospective study with objective assessments of the outcome and exposure before drawing conclusions on the possible synergistic effects of mechanical stressors and chemicals on the impairment of the median nerve.

Animal farming and the risk of lymphohaematopoietic cancers: a meta-analysis of three cohort studies within the AGRICOH consortium

OBJECTIVE

Animal farming entails a variety of potential exposures, including infectious agents, endotoxins and pesticides, which may play a role in the aetiology of lymphohaematopoietic cancers (LHCs). The aim of this study was to assess whether farming specific animal species is associated with the risk of overall LHC or its subtypes.

METHODS

Data from three prospective cohort studies in the USA, France and Norway which are part of the Agricultural Cohort consortium and which collected information about animal farming and cancer were used. Analyses included 316 270 farmers and farm workers. Adjusted Cox models were used to investigate the associations of 13 histological subtypes of LHC (n=3282) with self-reported livestock (cattle, pigs and sheep/goats) and poultry (ever/never and numbers raised) farming. Cohort-specific HRs were combined using random-effects meta-analysis.

RESULTS

Ever animal farming in general or farming specific animal species was not meta-associated with overall LHC. The risk of myeloid malignancies decreased with increasing number of livestock (p trend=0.01). Increased risk of myeloproliferative neoplasms was seen with increasing number of sheep/goats (p trend <0.01), while a decreased risk was seen with increasing number of livestock (p trend=0.02). Between cohorts, we observed heterogeneity in the association of type of animal farmed and various LHC subtypes.

CONCLUSIONS

This large-scale study of three prospective agricultural cohorts showed no association between animal farming and LHC risk, but few associations between specific animal species and LHC subtypes were observed. The observed differences in associations by countries warrant further investigations.

A task-based analysis of black carbon exposure in Iowa farmers during harvest

Diesel exhaust has been associated with adverse human health effects. Farmers are often exposed to diesel exhaust; however, their diesel exposure has not been well characterized. In this descriptive study, we measured black carbon concentrations as a proxy for diesel exhaust exposure in 16 farmers over 20 sampling days during harvest in southeast Iowa. Farmers wore a personal aethalometer which measured real-time black carbon levels throughout the working day, and their activities were recorded by a field researcher. Black carbon concentrations were characterized for each farmer, and by activity, vehicle fuel type, and microenvironment. Overall, 574 discrete tasks were monitored with a median task duration of 5.5 min. Of these tasks, 39% involved the presence of a diesel vehicle. Farmers' daily black carbon geometric mean exposures ranged from 0.1-2.3 µg/m³, with a median daily geometric mean of 0.3 µg/m³. The highest black carbon concentrations were measured on farmers who used or worked near diesel vehicles (geometric mean ranged from 0.5 µg/m³ while harvesting to 4.9 µg/m³ during animal work). Higher geometric means were found for near vs. far proximity to diesel-fueled vehicles and equipment (2.9 vs. 0.3 µg/m³). Indoor, bystander proximity to diesel-operated vehicles resulted in the highest geometric mean black carbon concentrations (18 µg/m³). Use of vehicles with open cabs had higher mean black carbon concentrations than closed cabs (2.1-3.2 vs. 0.4-0.9 µg/m³). In summary, our study provided evidence that farmers were frequently exposed to black carbon associated with diesel-related activities at levels above urban ambient concentrations in their daily work during harvest.

Livestock and poultry density and childhood cancer incidence in nine states in the USA

BACKGROUND

Parental occupational and childhood exposures to farm animals have been positively associated with childhood brain tumors, whereas associations with childhood leukemia are equivocal. The developing immune system may be influenced by allergen, virus, or other exposures from animal sources, which may contribute to childhood cancer incidence.

METHODS

Incident cancers (acute lymphoblastic leukemia [ALL], acute myeloid leukemia [AML], central nervous system [CNS], peripheral nervous system [PNS]) for children aged 0-4 diagnosed between 2003 and 2008 were obtained from nine National Cancer Institute Surveillance, Epidemiology and End Results (SEER) registries and were linked to U.S. Census of Agriculture data from 2002 and 2007 by county of diagnosis. Animal densities (animal units [AU]/km²; one animal unit is 1000 pounds of animal weight) were estimated for hogs, cattle, chickens (layers and broilers, separately), equine (horses, ponies, mules, burros, donkeys), goats, sheep, turkeys, and total animals. Animal density was examined in models as both continuous (AU per km²) and categorical variables (quartiles). Animal operation densities (per km²) by size of operation (cattle, hogs, chickens, sheep) were modeled continuously. Rate ratios and 95% confidence intervals were estimated using Poisson regression.

RESULTS

We found positive associations between AML and broiler chicken densities (RR_{per 10AU/km}² = 1.14, 95% CI = 1.02-1.26). ALL rates increased with densities of hog operations (RRper operation/100km² = 1.06, 95% CI = 1.02-1.11). PNS cancer rates were inversely associated with layer chicken density (RR_{per log of AU/km}² = 0.94, 95% CI = 0.89-0.99). No association was found between any cancer type and densities of cattle, equine, or goats.

CONCLUSIONS

Although limited by the ecologic study design, some of our findings are novel and should be examined in epidemiological studies with individual level data.

A principal factor analysis to characterize agricultural exposures among Nebraska veterans

Agricultural workers are at an increased risk of developing chronic respiratory disorders. Accurate estimation of long-term agricultural exposures based on questionnaires has been used to improve the validity of epidemiologic investigations and subsequent evaluation of the association between agricultural exposures and chronic diseases. Our aim was to use principal factor analysis (PFA) to distill exposure data into essential variables characterizing long-term agricultural exposures. This is a cross-sectional study of veterans between the ages of 40 and 80 years and who worked on a farm for ≥2 years. Participant characteristics were: 98.1% were white males with a mean age 65±8 (SD) years and 39.8% had chronic obstructive pulmonary disease. The final model included four factors and explained 16.6% of the variance in the exposure data. Factor 1 was a heterogeneous factor; however, Factor 2 was exclusively composed of exposure to livestock such as hogs, dairy and poultry. Factor 3 included exposures from jobs on or off the farm such as wood dust, mineral dust, asbestos and spray paint. Crop exposure loaded exclusively in Factor 4 and included lifetime hours of exposure and maximum number of acres farmed in the participants' lifetime. The factors in the final model were interpretable and consistent with farming practices.

Use of Dieselized Farm Equipment and Incident Lung Cancer: Findings from the Agricultural Health Study Cohort

BACKGROUND

Diesel exhaust is a known lung carcinogen. Farmers use a variety of dieselized equipment and thus may be at increased risk of lung cancer, but farm exposures such as endotoxins may also be protective for lung cancer.

OBJECTIVES

We evaluated the relative risk of incident lung cancer, including histological subtype, from enrollment (1993-1997) to 2010-2011 in relation to farm equipment use in the Agricultural Health Study (AHS), a prospective cohort study of pesticide applicators and spouses in Iowa and North Carolina, USA.

METHODS

Farm equipment use was reported by 21,273 farmers and 29,840 spouses. Rate ratios (RRs) were estimated separately for farmers and spouses with Poisson regression models adjusted for smoking and other confounders. We conducted stratified analyses by exposure to animals or stored grain, a surrogate for endotoxin exposure.

RESULTS

Daily diesel tractor use (vs. no use) was positively associated with lung cancer in farmers (RR = 1.48; 95% CI: 0.87, 2.50; 35 exposed, 32 unexposed cases), particularly adenocarcinoma (RR = 3.39; 95% CI: 1.23, 9.33; 12 exposed, 7 unexposed cases). The association of adenocarcinoma with daily (vs. low/no) use of diesel tractors was stronger for farmers with no animal or stored grain exposures (RR = 6.23; 95% CI: 2.25, 17.25; 5 exposed, 18 unexposed cases) than among farmers with these exposures (RR = 1.19; 95% CI: 0.51, 2.79; 7 exposed, 27 unexposed cases) (p-interaction = 0.05).

CONCLUSIONS

This study provides preliminary evidence of an increased risk of lung adenocarcinoma among daily drivers of diesel tractors and suggests that exposure to endotoxins may modify the impact of diesel exposure on lung cancer risk. Confirmation of these findings with more exposed cases and more detailed exposure information is warranted.

CITATION

Tual S, Silverman DT, Koutros S, Blair A, Sandler DP, Lebailly P, Andreotti G, Hoppin JA, Beane Freeman LE. 2016. Use of dieselized farm equipment and incident lung cancer: findings from the Agricultural Health Study Cohort. Environ Health Perspect 124:611-618; http://dx.doi.org/10.1289/ehp.1409238.

Pesticide Exposures and Body Mass Index (BMI) of Pesticide Applicators From the Agricultural Health Study

Endocrine-disrupting chemicals, including pesticides, may be associated with weight gain. This is the first longitudinal study to examine a potential association between weight gain and pesticides using data on 8,365 male pesticide applicators from the Agricultural Health Study (AHS) cohort established in 1993. The relationship between total cumulative days of exposure to pesticide functional/chemical classes and to the four most frequently used individual pesticides was studied in relation to body mass index (BMI) at the time of 5-yr follow-up (beginning in 1998) with the length of the exposure period dating back to age 20 yr. Multiple regression, Spearman correlation, ordinal logistic regression, and logistic regression models all utilized a Bonferroni-adjusted p value, were adjusted for relevant covariates, and were stratified by state of residence (Iowa/North Carolina) and presence/absence of weight-related health conditions. Adjusted multiple regression yielded statistically significant positive parameter estimates for the study sample and Iowa subgroups with consistent findings for triazine herbicides and atrazine: Change in BMI per 100 cumulative pesticide exposure days ranged from 0.07 to 0.11 for triazine herbicides and from 0.10 to 0.19 for atrazine. Ordinal logistic regression compared normal weight with overweight and with obese using the zero exposure category as referent. Statistically significant adjusted odds ratios identified for the study sample and both state subgroups for the highest level of atrazine exposure ranged from 1.4 to 1.7. Further investigation is warranted to evaluate the associations identified here.

Farm residence and lymphohematopoietic cancers in the Iowa Women's Health Study

BACKGROUND

Cancer incidence in male farmers has been studied extensively; however, less is known about risk among women residing on farms or in agricultural areas, who may be exposed to pesticides by their proximity to crop fields. We extended a previous follow-up of the Iowa Women's Health Study cohort to examine farm residence and the incidence of lymphohematopoietic cancers. Further, we investigated crop acreage within 750 m of residences, which has been associated with higher herbicide levels in Iowa homes.

METHODS

We analyzed data for a cohort of 37,099 Iowa women aged 55-69 years who reported their residence location (farm, rural (not a farm), town size based on population) at enrollment in 1986. We identified incident lymphohematopoietic cancers (1986-2009) by linkage with the Iowa Cancer Registry. Using a geographic information system, we geocoded addresses and calculated acreage of pasture and row crops within 750 m of homes using the 1992 National Land Cover Database. Cox regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) in multivariate analyses of cancer risk in relation to both residence location and crop acreage.

RESULTS

As found in an earlier analysis of residence location, risk of acute myeloid leukemia (AML) was higher among women living on farms (HR=2.23, 95%CI: 1.25-3.99) or rural areas (but not on a farm) (HR=1.95, 95%CI: 0.89-4.29) compared with women living in towns of >10,000 population. We observed no association between farm or rural residence and non-Hodgkin lymphoma (NHL; overall or for major subtypes) or multiple myeloma. In analyses of crop acreage, we observed no association between pasture or row crop acreage within 750 m of homes and risk of leukemia overall or for the AML subtype. Chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) risk was nonsignificantly elevated among women with pasture acreage within 750 m of their home (HRs for increasing tertiles=1.8, 1.8 and 1.5) and with row crop acreage within 750 m (HRs for increasing tertiles of acreage=1.4, 1.5 and 1.6) compared to women with no pasture or row crop acreage, respectively.

CONCLUSIONS

Iowa women living on a farm or in a rural area were at increased risk of developing AML, which was not related to crop acreage near the home. Living near pasture or row crops may confer an increased risk of CLL/SLL regardless of residence location. Further investigation of specific farm-related exposures and these cancers among women living on farms and in agricultural areas is warranted.

Public health risk assessment associated with heavy metal and arsenic exposure near an abandoned mine (Kirki, Greece)

The 'Agios Philippos' lead-zinc mine in the Kirki region (NE Greece) is now closed, but its legacy of heavy metal contamination remains at the site. At present, management of the contaminated land is of major concern. The area is in a reclamation process and requires immediate remediation action, whereas human risks need to be carefully evaluated. In order to assess these risks, samples from around the mine were collected and analyzed and a scenario involving the oral, dermal, and inhaled doses of arsenic and heavy metals was formulated. A Monte Carlo approach was undertaken, in order to model the average daily dose and quantify the corresponding hazard index and cancer risk. A toxicological risk was associated with samples collected in the vicinity of the mine (floatation, mine tailings) and a pronounced carcinogenic risk for arsenic was evident at the broader occupational/environmental setting. These findings urge for immediate rehabilitation actions that will mitigate population exposures and promote long-term environmental safety in the area.

Role of environment and sex differences in the development of autoimmune diseases: a roundtable meeting report

Autoimmune diseases (ADs) impose substantial health and financial burdens in the United States and in many parts of the world. Women are disproportionately affected by many of these disorders, which often contribute to lifelong disabilities. While the number of patients with some ADs appears to be rising, the complexities of conducting epidemiological studies prevent a thorough understanding of the prevalence and incidence of these various conditions. Research on environmental influences of these illnesses is limited, although they are generally hypothesized to result from the interaction of environmental agents in genetically susceptible individuals. Further, there is little known regarding the role of sex and gender in the environmentally influenced mechanisms leading to the development of AD. To address these issues, particularly the roles of environment and sex and gender in ADs and the factors that contribute to the rise in ADs, the Society for Women's Health Research convened an interdisciplinary roundtable of experts from academia, medicine, and government agencies to share their expertise, address knowledge gaps in research, and propose future research recommendations.

The effects of resveratrol against trifluralin toxicity in the urinary tract of rats

The herbicide itself and the degradation products are highly toxic on biological systems. The aim of this study is to investigate the potential toxic effects of trifluralin (TRF) on the urinary system of male rats and to investigate the protective effects of resveratrol (RSV) in TRF-induced urinary system damage. A total of 35 male Wistar rats were randomly divided into: (1) control group, (2) sham group, (3) low dose TRF group (0.8 g/kg/day), (4) high dose TRF group (2 g/kg/day) and (5) high dose TRF + RSV group 10 mg/kg/day. RSV was administered for 21 days by intragastric gavage at a dose of 10 mg/kg/day after induction of TRF. Kidney, ureter and urinary bladder tissue was examined using light microscopy and ultrastructurally. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling was performed to detect apoptosis. Superoxide dismutase (SOD), glutathion peroxidase (GPx) and malondialdehyde (MDA) levels were also evaluated biochemically for oxidative stress parameters. Histological evaluation showed that TRF increases apoptosis and oxidative stress, causes histological tissue damages and biochemical changes in the kidneys but does not cause any damage to the ureter and bladder. Treatment with RSV significantly attenuated tissue damage in the urinary system of rats. Apopitotic cells were significantly decreased in the treatment group. Additionally, treatment with RSV decreased SOD and GPx levels and increased MDA levels in the kidney tissue of animals subjected to TRF. These results show that RSV can significantly minimize histological damage and biochemical differences in treating TRF-induced kidney injury in rats.

Lifetime pesticide use and telomere shortening among male pesticide applicators in the Agricultural Health Study

BACKGROUND

Telomere length (TL) in surrogate tissues may be influenced by environmental exposures.

OBJECTIVE

We aimed to determine whether lifetime pesticides use is associated with buccal cell TL.

METHODS

We examined buccal cell TL in relation to lifetime use of 48 pesticides for 1,234 cancer-free white male pesticide applicators in the Agricultural Health Study (AHS), a prospective cohort study of 57,310 licensed pesticide applicators. Participants provided detailed information on lifetime use of 50 pesticides at enrollment (1993-1997). Buccal cells were collected from 1999 to 2006. Relative telomere length (RTL) was measured using quantitative real-time polymerase chain reaction. We used linear regression modeling to evaluate the associations between specific pesticides and the logarithm of RTL, adjusting for age at buccal cell collection, state of residence, applicator license type, chewing tobacco use, and total lifetime days of all pesticide use.

RESULTS

The mean RTL for participants decreased significantly in association with increased lifetime days of pesticide use for alachlor (p = 0.002), 2,4-dichlorophenoxyacetic acid (2,4-D; p = 0.004), metolachlor (p = 0.01), trifluralin (p = 0.05), permethrin (for animal application) (p = 0.02), and toxaphene (p = 0.04). A similar pattern of RTL shortening was observed with the metric lifetime intensity-weighted days of pesticide use. For dichlorodiphenyltrichloroethane (DDT), we observed significant RTL shortening for lifetime intensity-weighted days (p = 0.04), but not for lifetime days of DDT use (p = 0.08). No significant RTL lengthening was observed for any pesticide.

CONCLUSION

Seven pesticides previously associated with cancer risk in the epidemiologic literature were inversely associated with RTL in buccal cell DNA among cancer-free pesticide applicators. Replication of these findings is needed because we cannot rule out chance or fully rule out bias.

Increased cancer burden among pesticide applicators and others due to pesticide exposure

A growing number of well-designed epidemiological and molecular studies provide substantial evidence that the pesticides used in agricultural, commercial, and home and garden applications are associated with excess cancer risk. This risk is associated both with those applying the pesticide and, under some conditions, those who are simply bystanders to the application. In this article, the epidemiological, molecular biology, and toxicological evidence emerging from recent literature assessing the link between specific pesticides and several cancers including prostate cancer, non-Hodgkin lymphoma, leukemia, multiple myeloma, and breast cancer are integrated. Although the review is not exhaustive in its scope or depth, the literature does strongly suggest that the public health problem is real. If we are to avoid the introduction of harmful chemicals into the environment in the future, the integrated efforts of molecular biology, pesticide toxicology, and epidemiology are needed to help identify the human carcinogens and thereby improve our understanding of human carcinogenicity and reduce cancer risk.

Agricultural exposures and stroke mortality in the Agricultural Health Study

Exposures associated with common agricultural activities may increase risk of stroke. The authors evaluated associations between self-reported agricultural activities including pesticide use and handling of crops and stroke mortality among 51,603 male pesticide applicators enrolled in the Agricultural Health Study (AHS). Vital status was obtained through 2008. Stroke mortality was defined by underlying or contributing cause of death (ICD-9 430-438, ICD-10 I60-I69). Information regarding lifetime pesticide use, working with crops or animals, engagement in other agricultural activities, and potential confounders was self-reported at enrollment. Cox proportional hazards models, with age as the time scale, were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) adjusted for state of residence, smoking status, and alcohol consumption. Median follow-up time was 13 yr, during which 308 stroke deaths occurred. No measure of overall or specific pesticide use was positively associated with mortality due to stroke. Stroke mortality was inversely associated with handling hay, grain, or silage at least once each year as reported at enrollment (HR: 0.75; 95% CI: 0.58, 0.98). There was no evidence of an association between pesticide use and stroke mortality. The inverse association between handling of hays and grains and stroke mortality may be due to (1) those engaging in such activities being healthier than those who did not or (2) exposure to some biological agent present in hays and grains. Further investigation of incident stroke, rather than stroke mortality, as well as stroke subtypes, is needed to determine the full role of agricultural exposures and stroke.

A review of pesticide exposure and cancer incidence in the agricultural health study cohort

We reviewed epidemiologic evidence related to occupational pesticide exposures and cancer incidence in the Agricultural Health Study (AHS) cohort. Studies were identified from the AHS publication list available on a Medline/PubMed database search in March 2009. Findings related to lifetime-days and/or intensity-weighted lifetime-days of pesticide use are the primary focus of this review, because these measures allow for the evaluation of potential exposureresponse relationships. Most of the 32 pesticides examined were not strongly associated with cancer incidence in pesticide applicators. Increased rate ratios and positive exposureresponse patterns were reported for 12 pesticides currently registered in Canada and/or the United States. Exposure misclassification is also a concern in the AHS and may limit the analysis of exposureresponse patterns. Epidemiologic evidence outside the AHS remains limited with respect to most of the observed associations, but animal toxicity data support the biological plausibility of relationships observed six pesticides. Continued follow-up is needed to clarify associations reported to date. In particular, further evaluation of registered pesticides is warranted.

Occupational pesticide exposures and cancer risk: a review

A review of the epidemiological literature linking pesticides to cancers in occupational studies worldwide was conducted, with particular focus on those articles published after the release of IARC Monograph 53 (1991): Occupational Exposures in Insecticide Applications and Some Pesticides. Important new data are now available. Chemicals in every major functional class of pesticides including insecticides, herbicide, fungicides, and fumigants have been observed to have significant associations with an array of cancer sites. Moreover, associations were observed with specific chemicals in many chemical classes of pesticides such as chlorinated, organophosphate, and carbamate insecticides and phenoxy acid and triazine herbicides. However, not every chemical in these classes was found to be carcinogenic in humans. Twenty-one pesticides identified subsequent to the last IARC review showed significant exposure-response associations in studies of specific cancers while controlling for major potential confounders. This list is not an exhaustive review and many of these observations need to be evaluated in other epidemiological studies and in conjunction with data from toxicology and cancer biology. Nonetheless, it is reasonable and timely for the scientific community to provide a multidisciplinary expert review and evaluation of these pesticides and their potential to produce cancer in occupational settings.

Disproportionate exposures in environmental justice and other populations: the importance of outliers

We examined traditional environmental justice populations and other groups whose exposure to contaminants is often disproportionately high. Risk assessment methods may not identify these populations, particularly if they are spatially dispersed. We suggest using a National Health and Nutrition Examination Survey approach to oversample minority communities and develop methods for assessing exposure at different distances from pollution sources; publishing arithmetic and geometric means and full distributions for minority populations; and paying particular attention to high-end exposures. Means may sufficiently characterize populations as a whole but are inadequate in identifying vulnerable groups and subgroups. The number of individuals above the 95th percentile of any distribution may be small and unrepresentative, but these outliers are the ones who need to be protected.

An update of cancer incidence in the Agricultural Health Study

OBJECTIVE

Our objective is to reevaluate cancer incidence among Agricultural Health Study participants.

METHODS

Standardized incidence ratios (SIRs) and relative standardized ratios were calculated.

RESULTS

A significant excess of prostate cancer was seen for private and commercial applicators (SIR = 1.19, 95% CI 1.14, 1.25 and SIR = 1.28, 95% CI = 1.00, 1.61, respectively). Excesses were observed for lip cancer (SIR = 1.97, 95% CI = 1.02, 3.44) and multiple myeloma (SIR = 1.42, 95% CI = 1.00, 1.95) among private applicators from North Carolina and for marginal zone lymphoma among Iowa spouses (SIR = 2.34, 95% CI = 1.21, 4.09).

CONCLUSIONS

Although lower rates of smoking and increased physical activity probably contribute to the lower overall cancer incidence, agricultural exposures including pesticides, viruses, bacteria, sunlight, and other chemicals may increase risks for specific cancer sites.

A review of pesticide exposure and cancer incidence in the Agricultural Health Study cohort

OBJECTIVE

We reviewed epidemiologic evidence related to occupational pesticide exposures and cancer incidence in the Agricultural Health Study (AHS) cohort.

DATA SOURCES

Studies were identified from the AHS publication list available at http://aghealth.nci.nih.gov as well as through a Medline/PubMed database search in March 2009. We also examined citation lists. Findings related to lifetime-days and/or intensity-weighted lifetime-days of pesticide use are the primary focus of this review, because these measures allow for the evaluation of potential exposure-response relationships.

DATA SYNTHESIS

We reviewed 28 studies; most of the 32 pesticides examined were not strongly associated with cancer incidence in pesticide applicators. Increased rate ratios (or odds ratios) and positive exposure-response patterns were reported for 12 pesticides currently registered in Canada and/or the United States (alachlor, aldicarb, carbaryl, chlorpyrifos, diazinon, dicamba, S-ethyl-N,N-dipropylthiocarbamate, imazethapyr, metolachlor, pendimethalin, permethrin, trifluralin). However, estimates of association for specific cancers were often imprecise because of small numbers of exposed cases, and clear monotonic exposure-response patterns were not always apparent. Exposure misclassification is also a concern in the AHS and may limit the analysis of exposure-response patterns. Epidemiologic evidence outside the AHS remains limited with respect to most of the observed associations, but animal toxicity data support the biological plausibility of relationships observed for alachlor, carbaryl, metolachlor, pendimethalin, permethrin, and trifluralin.

CONCLUSIONS

Continued follow-up is needed to clarify associations reported to date. In particular, further evaluation of registered pesticides is warranted.

Farmer exposure to organic solvents during the maintenance and repair of farm machinery: a pilot study

BACKGROUND

The maintenance/repair of farm machinery is a common farming activity. Dermal exposure to organic solvents has not been well documented. A pilot study was conducted to characterize exposure to organic solvents.

METHODS

A survey questionnaire was administered to 31 Kentucky farmers in 2008. Dermal exposure assessment was conducted in 10 farmers while farmers performed farm machinery maintenance/repair tasks using a solvent sampling patch. Benzene, toluene, xylene, and n-hexane were analyzed.

RESULTS

All four organic solvents were identified from the samples with toluene (<0.5-36,000 microg/patch) and xylene (15-5,700 microg/patch) at significantly higher levels. Twenty-six farmers reported the use of personal protective equipment <50% of their time repairing/maintaining farm machinery on the questionnaire; only two farmers wore gloves during the exposure assessment.

CONCLUSIONS

Farmers routinely use solvent products for farm machinery maintenance/repair. Dermal exposure to organic solvents is a potential hazard. Further studies to characterize and evaluate exposure in larger samples of farmers are needed.

Occupational exposure to metribuzin and the incidence of cancer in the Agricultural Health Study

PURPOSE

Little is known about the potential carcinogenicity of the triazinone herbicide metribuzin. We evaluated the association between metribuzin use and cancer risk in the Agricultural Health Study, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina.

METHODS

Applicators (N=23,072) provided information on metribuzin use on a self-administered questionnaire at enrollment (1993-1997). Among metribuzin users (n=8,504), there were 554 incident cancer cases. We used multivariable Poisson regression to evaluate potential associations between metribuzin use and cancer incidence by using two quantitative exposure metrics, lifetime days and intensity-weighted lifetime days.

RESULTS

Using intensity-weighted lifetime days, the rate ratio (RR) and 95% confidence interval (CI) for the highest exposed tertile for lymphohematopoietic malignancies were 2.09 (95% CI: 0.99-4.29), p trend=0.02 and 2.42 (95% CI: 0.82-7.19), p trend=0.08 for leukemia. For non-Hodgkin lymphoma, the RR was 2.64 (95% CI: 0.76-9.11), p trend=0.13 for lifetime days and 2.52 (95% CI: 0.66-9.59), p trend=0.13 for intensity-weighted lifetime days. Patterns of association were similar for both exposure metrics, but associations were generally weaker than for intensity-weighted days.

CONCLUSIONS

The results from this study suggest a potential association between metribuzin use and certain lymphohematopoietic malignancies; however, having not been observed previously, caution should be used in interpretation.

Cancer incidence among pesticide applicators exposed to permethrin in the Agricultural Health Study

BACKGROUND

Permethrin is a synthetic pyrethroid insecticide widely used in agriculture, in public health, and in many U.S. homes and gardens.

OBJECTIVE

In this study we evaluated the incidence of cancer among pesticide applicators exposed to permethrin in the Agricultural Health Study (AHS).

METHODS

A total of 49,093 pesticide applicators were included in this analysis of the AHS, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina. Detailed information on pesticide exposure and lifestyle factors was obtained from self-administered questionnaires completed in 1993-1997. Average length of follow-up since applicator enrollment in the cohort was 9.14 years. We used two permethrin exposure metrics: a) lifetime days applicators personally mixed or applied permethrin and b) intensity-weighted lifetime days (lifetime days weighted by estimated intensity of exposure). We used Poisson regression analysis to estimate relative risks (RRs) and 95% confidence intervals (CIs) for malignancies by tertiles of exposure.

RESULTS

We found no associations between permethrin and all malignant neoplasms combined, or between permethrin and melanoma, non-Hodgkin lymphoma, leukemia, or cancers of the colon, rectum, lung, or prostate. We found elevated and statistically significant risks for multiple myeloma in the highest tertiles of both lifetime exposure-days (RR = 5.72; 95% CI, 2.76-11.87) and intensity-weighted lifetime exposure-days (RR = 5.01; 95% CI, 2.41-10.42), compared with applicators reporting they never used permethrin; these results are based on only 15 exposed cases. These findings were similar across a variety of alternative exposure metrics, exposure categories, and reference groups.

CONCLUSIONS

This study found no association with most cancers analyzed. Although the suggested association with multiple myeloma was based on a small number of cases, it warrants further evaluation.

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.

Carbaryl exposure and incident cancer in the Agricultural Health Study

Carbaryl is a carbamate insecticide with a broad spectrum of uses in agricultural, commercial and household settings. It has previously been linked with non-Hodgkin lymphoma (NHL) but studies of cancer risk in humans are limited. We examined occupational carbaryl use and risk of all cancers in the Agricultural Health Study, a prospective study of a cohort of pesticide applicators in North Carolina and Iowa. This analysis included 21,416 subjects (1,291 cases) enrolled from 1993-1997 and followed for cancer incidence through 2003. Pesticide exposure and other data were collected using self-administered questionnaires. Poisson regression was used to calculate rate ratios (RRs) and 95% confidence intervals (CIs) while controlling for potential confounders. Carbaryl was not associated with cancer risk overall. Relative to subjects who never used carbaryl, melanoma risk was elevated with >175 lifetime exposure-days (RR = 4.11; 95%CI, 1.33-12.75; p-trend = 0.07), >10 years of use (RR = 3.19; 95%CI, 1.28-7.92; p-trend = 0.04), or >or=10 days of use per year (RR = 5.50; 95%CI, 2.19-13.84; p-trend < 0.001). Risk remained after adjusting for sunlight exposure. Although not significant, there appeared to be a trend of decreasing prostate cancer risk with increasing level of exposure. A small increase in NHL risk was observed using some, but not all, exposure measures. No associations were observed with other examined cancer sites. Because the observed results were not hypothesized a priori and because of limited study of their biological plausibility, they should be interpreted with caution.

Fonofos exposure and cancer incidence in the agricultural health study

BACKGROUND

The Agricultural Health Study (AHS) is a prospective cohort study of licensed pesticide applicators from Iowa and North Carolina enrolled 1993-1997 and followed for incident cancer through 2002. A previous investigation in this cohort linked exposure to the organophosphate fonofos with incident prostate cancer in subjects with family history of prostate cancer.

OBJECTIVES

This finding along with findings of associations between organophosphate pesticides and cancer more broadly led to this study of fonofos and risk of any cancers among 45,372 pesticide applicators enrolled in the AHS.

METHODS

Pesticide exposure and other data were collected using self-administered questionnaires. Poisson regression was used to calculate rate ratios (RRs) and 95% confidence intervals (CIs) while controlling for potential confounders.

RESULTS

Relative to the unexposed, leukemia risk was elevated in the highest category of lifetime (RR = 2.24; 95% CI, 0.94-5.34, Ptrend = 0.07) and intensity-weighted exposure-days (RR = 2.67; 95% CI, 1.06-6.70, Ptrend = 0.04), a measure that takes into account factors that modify pesticide exposure. Although prostate cancer risk was unrelated to fonofos use overall, among applicators with a family history of prostate cancer, we observed a significant dose-response trend for lifetime exposure-days (Ptrend = 0.02, RR highest tertile vs. unexposed = 1.77, 95% CI, 1.03-3.05; RRinteraction = 1.28, 95% CI, 1.07-1.54). Intensity-weighted results were similar. No associations were observed with other examined cancer sites.

CONCLUSIONS

Further study is warranted to confirm findings with respect to leukemia and determine whether genetic susceptibility modifies prostate cancer risk from pesticide exposure.

Survey of urinary nickel in residents of areas with a high density of electroplating factories

The soil metal contamination arising from the discharge of the high density of electroplating factories in the geographic center of Taiwan has prompted concern about human exposure to harmful metals. This study aimed to determine the levels of nickel (Ni) in urine of residents living in the high vs. low factory-density areas, and to examine how these levels relate to gender and age. A total of 660 subjects, resident in the area for the last five years, were sampled according to the stratified random sampling approach, at ages 35-44, 45-54, and 55-64years for both genders. Metals in urine samples were analyzed by inductively coupled plasma mass spectrometry (ICPMS). The geometric mean (95% confidence interval (CI)) of urinary Ni was 6.30 (5.99-6.62)mug/l. The 0.95 parametric reference interval (90% CI) of urinary Ni was estimated to be 1.74 (1.62-1.88) to 22.73 (21.14-24.44)mug/l. Subjects in the areas with a high density of electroplating factories had significantly higher urinary Ni levels than those in the low-density areas, but both types of areas had obviously higher urinary Ni levels when compared to the non-occupationally exposed population from western countries. The health significance of elevated urinary Ni and its causative factors remain to be determined.

Phorate exposure and incidence of cancer in the agricultural health study

BACKGROUND

We recently reported a link between use of the organophosphate pesticide phorate and risk of prostate cancer among applicators with a family history of prostate cancer in the Agricultural Health Study (AHS).

OBJECTIVE

This finding, together with findings of associations between other organophosphate pesticides and cancer more broadly, prompted us to examine phorate exposure and overall cancer incidence in the AHS. Adding 3 years of follow-up and using more detailed exposure information allowed us to see whether the prostate cancer finding held.

METHODS

The AHS is a prospective study of licensed restricted-use pesticide applicators from North Carolina and Iowa. To our knowledge, this is the largest examination of workers occupationally exposed to phorate. Pesticide exposure and other information was collected using two self-administered questionnaires completed from 1993 to 1997. Poisson regression was used to calculate rate ratios (RR) and 95% confidence intervals (CI), adjusting for potential confounders.

RESULTS

Phorate use was not related to the incidence of all cancers combined or to any individual cancer, although we had insufficient numbers to study non-Hodgkin lymphoma or leukemia, which have been linked to organophosphates in other studies. Although prostate cancer risk was not significantly related to phorate use overall or among those without a family history, the risk tended to increase among applicators with a family history of prostate cancer. The interaction RR was 1.53 (95% CI, 0.99-2.37).

CONCLUSION

The observed statistical interaction suggests a gene-environment interaction between family history and phorate exposure in the incidence of prostate cancer, but other explanations are also possible.

Comparison of Farmers in the Agricultural Health Study to the 1992 and 1997 Censuses of Agriculture

CONTEXT

The Agricultural Health Study (AHS) is a large, prospective cohort study in the states of Iowa and North Carolina that has been developed to better understand how pesticides and other agricultural exposures relate to the occurrence of cancer and other diseases.

PURPOSE

This report compares the characteristics of AHS farmers to the Census of Agriculture to evaluate the generalizability of AHS findings.

METHODS

We restricted the AHS to private pesticide applicators who enrolled in Iowa (n = 31,065) and in North Carolina (n = 17,239) between 1993 and 1997, and who identified themselves as living or working on a farm. We compared their self-reported data with data from the 1992 and 1997 Censuses of Agriculture.

FINDINGS

AHS farmers in Iowa are younger; live or work on larger farms; more frequently apply herbicides, insecticides, and fungicides; and are more likely to raise beef cattle and swine, and grow corn, soybeans, hay, and oats. AHS farmers in North Carolina are also younger, live or work on larger farms, more frequently reported growing crops commonly seen in the state, and are more frequent pesticide users. However, animals raised are similar to those in the North Carolina Census of Agriculture.

CONCLUSIONS

AHS farmers likely represent the higher end of pesticide usage in both states in part because AHS farmers have larger farms. Since the health effects of pesticides are best ascertained among pesticide users with the greatest exposure, the AHS cohort should prove to be a valuable resource for health effects research.

Factor analysis of pesticide use patterns among pesticide applicators in the Agricultural Health Study

Exposure to certain pesticides has been linked with both acute and chronic adverse health outcomes such as neurotoxicity and risk for certain cancers. Univariate analyses of pesticide exposures may not capture the complexity of these exposures since use of various pesticides often occurs simultaneously, and because specific uses have changed over time. Using data from the Agricultural Health Study, a cohort study of 89,658 licensed pesticide applicators and their spouses in Iowa and North Carolina, we employed factor analysis to order to characterize underlying patterns of self-reported exposures to 50 different pesticides. Factor analysis is a statistical method used to explain the relationships between several correlated variables by reducing them to a smaller number of conceptually meaningful, composite variables, known as factors. Three factors emerged for farmer applicators (N=45,074): (1) Iowa agriculture and herbicide use, (2) North Carolina agriculture and use of insecticides, fumigants and fungicides, and (3) older age and use of chlorinated pesticides. The patterns observed for spouses of farmers (N=17,488) were similar to those observed for the farmers themselves, whereas five factors emerged for commercial pesticide applicators (N=4,384): (1) herbicide use, (2) older age and use of chlorinated pesticides, (3) use of fungicides and residential pest treatments, (4) use of animal insecticides, and (5) use of fumigants. Pesticide exposures did not correlate with lifestyle characteristics such as race, smoking status or education. This heterogeneity in exposure patterns may be used to guide etiologic studies of health effects of farmers and other groups exposed to pesticides.

Disease and injury among participants in the Agricultural Health Study

The Agricultural Health Study (www.aghealth.org) is a cohort of 89,658 pesticide applicators and their spouses from Iowa and North Carolina assembled between 1993 and 1997 to evaluate riskfactorsfor disease in ruralfarm populations. This prospective study is just now reaching sufficient maturity for analysis of many disease endpoints. Nonetheless, several analyses have already provided interesting and important leads regarding disease patterns in agricultural populations and etiologic clues for the general population. Compared to the mortality experience of the general population in the two states (adjusted for race, gender, age and calendar time), the cohort experienced a very low mortality rate overall and for many specific causes and a low rate of overall cancer incidence. A few cancers, however, appear elevated, including multiple myeloma and cancers of the lip, gallbladder, ovary, prostate, and thyroid, but numbers are small for many cancers. A study of prostate cancer found associations with exposure to several pesticides, particularly among individuals with a family history of prostate cancer. Links to pesticides and other agricultural factors have been found for injuries, retinal degeneration, and respiratory wheeze. Methodological studies have determined that information collected by interview is unbiased and reliable. A third round of interviews scheduled to begin in 2005 will collect additional information on agricultural exposures and health outcomes. The study can provide data to address many health issues in the agricultural community. The study investigators welcome collaboration with interested scientists.

Cancer Incidence Among Pesticide Applicators Exposed to Chlorpyrifos in the Agricultural Health Study

BACKGROUND

Chlorpyrifos is one of the most widely used insecticides in the United States. We evaluated the incidence of cancer among pesticide applicators exposed to chlorpyrifos in the Agricultural Health Study, a prospective cohort study of licensed pesticide applicators in Iowa and North Carolina.

METHODS

A total of 54,383 pesticide applicators were included in this analysis. Detailed information on pesticide exposure and lifestyle factors was obtained from self-administered questionnaires completed at the time of enrollment (December 1993-December 1997). Poisson regression analysis was used to evaluate the association between chlorpyrifos exposure and cancer incidence after adjustment for potential confounders. All statistical tests were two-sided.

RESULTS

A total of 2070 incident malignant neoplasms were diagnosed through 2001. The rate ratio for all cancers combined among chlorpyrifos-exposed applicators compared with nonexposed applicators was 0.97 (95% confidence interval = 0.87 to 1.08). For most cancers analyzed, there was no evidence of an exposure-response relationship. However, the incidence of lung cancer was statistically significantly associated with both chlorpyrifos lifetime exposure-days (P(trend) = .002) and chlorpyrifos intensity-weighted exposure-days (P(trend) = .036). After adjustment for other pesticide exposures and demographic factors, individuals in the highest quartile of chlorpyrifos lifetime exposure-days (>56 days) had a relative risk of lung cancer 2.18 (95% confidence interval = 1.31 to 3.64) times that of those with no chlorpyrifos exposure.

CONCLUSION

Our findings suggest an association between chlorpyrifos use and incidence of lung cancer that deserves further evaluation.

Diesel exhaust, solvents, and other occupational exposures as risk factors for wheeze among farmers

Farmers engage in activities that result in exposure to diesel exhaust, solvents, welding fumes, and other respiratory irritants. Using the Agricultural Health Study, a cohort of pesticide applicators in Iowa and North Carolina, we evaluated the odds of wheeze associated with nonpesticide occupational exposures. We used logistic regression models controlling for age, state, smoking, and history of asthma or atopy to evaluate odds of wheeze in the past year among the 20898 farmers who provided complete information on all covariates. Driving diesel tractors was associated with elevated odds of wheeze (odds ratio = 1.31; 95% confidence interval = 1.13, 1.52); the odds ratio for driving gasoline tractors was 1.11 (95% confidence interval = 1.02, 1.21). A duration-response relationship was observed for driving diesel tractors but not for driving gasoline tractors. Activities involving solvent exposure, including painting and use of solvents for cleaning, were associated with an increased odds of wheeze in a duration-dependent fashion. The highest odds of wheeze for farm activities were for daily painting (odds ratio = 1.82; 95% confidence interval = 0.89, 3.73), an indication of daily solvent exposure. These results add to the growing body of evidence of adverse respiratory effects of diesel exposure on the lung and suggest exposure to solvents may contribute as well.