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Logo of oenvmedOccupational and Environmental MedicineVisit this articleSubmit a manuscriptReceive email alertsContact usBMJ
 
Occup Environ Med. 2007 December; 64(12): e39.
PMCID: PMC2095368

Agriculture 1

202 Farming exposure and early‐onset prostate cancer

B. H. Alexander1, T. R. Church1, D. J. Reding2. 1University of Minnesota School of Public Health; 2Marshfield Clinic Research Foundation

ObjectivesTo examine the hypotheses that early‐onset prostate cancer are associated with age specific general farming exposures and exposure to triazine herbicides.

MethodsA population‐based case‐control study of prostate cancer recruited all early‐onset cases (diagnosed under age 60; n = 1198) and 10% of late‐onset cases (diagnosed age 60–79; n = 385) from Minnesota and Wisconsin state cancer registries. Controls were selected from state drivers' license/ID records and frequency matched by age. In‐person interviews ascertained history of living or working on a farm or ranch, specific pesticide exposures, demographic information, lifestyle, medical history, and family history of cancer. Total fat intake came from a self‐administered food frequency questionnaire. A cumulative triazine exposure index was based on the number of applications per year and years of application of all triazine chemicals. General farming exposures from living or working on a farm were classified as exposure only as a child, as a child and an adult, and only as an adult. Odds ratios (OR) and 95% confidence intervals (CI) for early and late onset prostate cancer were estimated using a logistic regression controlling for potential confounders.

ResultsCompared to men who reported no farming exposure, the risk of early‐onset prostate cancer was not associated with living or working on a farm only as a child (OR 0.97, 95% CI 0.78 to 1.19) or as a child and an adult (0.86, 95% CI 0.72 to 1.16), but may be lower when exposed only as an adult (OR 0.61, 95% CI 0.37 to 1.02). Risk of later onset prostate cancer was associated with childhood‐only exposure (OR 1.43, 95% CI 1.02 to 2.00), but not exposure as an adult and child (OR 1.04, 95% CI 0.72 to 1.50) or only as an adult (OR 0.61, 95% CI 0.24 to 1.57). Compared to men with no triazine exposure, the risk of early‐onset prostate cancer was marginally greater for exposure above the median exposure index (OR 1.49, 95% CI 0.90 to 2.46); this association was limited to men without a family history of prostate cancer (OR 1.64, 95% CI 0.94 to 2.87).

ConclusionAssociations between farming exposures and prostate cancer may differ by age of diagnosis and by age of exposure.

Key wordsprostate cancer; farming exposures; triazine herbicides

203 Pesticide exposure epidemiology among cut‐flower farmers in the Philippines

J. Lu. National Institutes of Health, University of the Philippines, Manila

ObjectivesTo determine pesticide exposure, work and safety practices, individual and family illnesses, and cholinesterase levels.

MethodsThis is a follow‐up study on the adverse health effects associated with pesticide exposure among cut‐flower farmers in La Trinidad, Benguet. Survey questionnaires and detailed physical and laboratory examinations were administered to 114 and 102 respondents, respectively.

ResultsResults showed that pesticide application was the most frequent activity associated with pesticide exposure, and entry was mostly ocular and dermal. The majority of those exposed were symptomatic, with the most common complaints being allergic in nature and involving the head, eyes, ears, nose and throat (eye tearing, itchiness and redness, cough, dizziness). HEENT (Head, ear, eyes, nose and throat) symptoms (blurring of vision, deafness, headache) were also predominant among the farmers. Involvement of the skin was also noted, with 21% of farmers having integumentary abnormalities. On physical examination, 90 or 88.2% of those examined were found to have abnormal peak expiratory flow rate (PEFR). 82% per cent had abnormal temperature, followed by abnormal general survey findings (eg, cardio‐respiratory distress). 51% had cholinesterase levels below the mean value of 0.7 Δ pH/h, and 25.5% exhibited a more than 10% depression in the level of RBC cholinesterase. Certain haematological parameters were also abnormal, namely haemoglobin, haematocrit and eosinophil count. Using Pearson's r, factors strongly associated with illness due to pesticides include using a contaminated piece of fabric to wipe sweat off (p = 0.01) and reusing pesticide containers to store water (p = 0.01). Recycling of containers poses great health hazards and risks of contamination, and the current recommendation is that used containers should be buried. There is a moderate relationship between illness and average number of years of using pesticides (p = 0.05), and re‐entering a recently sprayed area (p = 0.05). Those with motor scale scores of equal or less than 15 indicating normal values are less likely to be sick. The greatest adverse effect of those exposed is an abnormal cholinesterase level which confirms earlier studies on the effects of pesticides on the body.

ConclusionThe study showed that pesticide exposure is associated with health problems and an associated abnormal cholinesterase level.

Key wordspesticide exposure; cholinesterase; cut flower farmers

204 Case‐control study of prostate cancer nested in a cohort of sheep owners exposed to hexachlororcyclohexane

V. Rafnsson. Department of Preventive Medicine, University of Iceland

ObjectivesThe objective of this study was to investigate the association between prostate cancer and exposure to hexachlorocyclohexane (HCH), sustained while sheep dipping.

MethodsThis is a case‐control study nested in a cohort of 7882 individuals, collected from records on sheep dipping. Sheep owners were obligated by law to dip their sheep to combat ectoparasites and the number of dipped sheep was use as a surrogate of the intensity of dermal exposure. HCH was the only drug used for sheep dipping from 1947 to 1986. It initially contained a mixture of isomers but later γ‐HCH. Cases (n = 536) were identified by record linkage with the national cancer registry (through 1962 to 2003) and controls (n = 2276) were selected at random from the cohort. Logistic regression analysis was used to calculate the odds ratio for prostate cancer, adjusted for age.

ResultsThe crude odds ratio for prostate cancer was 0.94 (95% CI 0.77 to 1.15) for the sheep owner who had 100 sheep or more as compared to those who had less than 100 sheep. The odds ratio for prostate cancer associated with number of owned sheep, adjusted for age, was 1.0005 (95% CI 0.9998 to 1.0013).

ConclusionThe low odds ratios and narrow confidence intervals, which included unity, do not indicate that prostate cancer is associated with exposure to HCH. The size of the study, the specific exposure, and the surrogate of the exposure, which could be graduated with considerable accuracy, indicate true negative results.

Key wordscancer registry; dermal exposure; sheep dipping

205 Where do farmers get their pesticide exposure from? Application versus background exposures

R. Vermeulen1, B. Bakke2, L. Beane‐Freeman3, P. Stewart3, A. Blair3, D. B. Barr4, C. F. Lynch5, R. Allen6, M. Alavanja3, A. De Roos7. 1Institute for Risk Assessment Sciences, Utrecht University; 2National Institute of Occupational Health, Oslo, Norway; 3National Cancer Institute, Rockville, MD, USA; 4Centers for Disease Control and Prevention, Atlanta, GA, USA; 5College of Public Health, University of Iowa, Iowa City, IA, USA; 6U.S. Environmental Protection Agency, Washington, DC, USA; 7University of Washington Department of Epidemiology, Seattle, WA, USA

ObjectivesFarmers may be exposed to pesticides when mixing, loading and applying (MLA) pesticides. After application they may be exposed if they work in treated fields or if equipment, work clothing or the home environment is contaminated with pesticides. Traditionally, exposure assessment for pesticides has focused on exposure levels during MLA activities. Relatively few data are available on exposure during non‐application days (background levels).

MethodsRepeated urine samples (n = 6–10) were collected during a year from 30 corn farmers and 10 non‐farming controls. The first urine sample collection from farmers was timed to coincide with atrazine, and occasionally, 2,4‐D applications. The timing of the other urine collections (background samples) were at fixed time intervals during a whole year (winter, planting and growing season) but independent of pesticide applications. Urine samples (n = 367) were analysed for a standard panel of 14 non‐persistent pesticides using HPLC‐MS/MS. Daily and weekly diaries collected information on pesticides used and farming and lifestyle activities. The number of urine samples above the LOD for a specific pesticide among farmers and controls were compared using Fisher's exact test. Levels of pesticide‐(metabolites) were compared using mixed‐effect models.

ResultsPercents of background urine samples above the LOD (ie, samples not directly related to a specific pesticide application) were similar between farmers and controls for most pesticide metabolites and parent compounds measured. The exceptions were atrazine mercapturate (38% vs 6%), 2,4‐D (92% vs 47%) and acetochlor mercapturate (45% vs 4%). These pesticides showed clear statistical differences in background concentrations between farmers and controls (p<0.0001 for all three pesticides) with a distinct seasonal pattern in background levels (higher during the planting season than in the growing or off‐season). Elevated levels could not be explained by recent applications.

ConclusionElevated urinary levels of non‐persistent pesticides seem to be present among farmers when compared to controls even during non‐application periods. Although lower than during application activities, these exposures might be non‐trivial. It is therefore concluded that common methods of focusing on MLA activities of pesticides could underestimate and/or misclassify exposure since background levels (ie, off‐season, growing season) are frequently ignored.

Key wordspesticides; exposure assessment; farming

206 Does physical activity at work affect blood lipid profiles contributing to favourable health outcomes in farmers?

K. C. Nordby1, A. T. Hostmark2, P. Kristensen1. 1National Institute of Occupational Health, Oslo, Norway; 2Section of Preventive Medicine and Epidemiology, University of Oslo, Norway

ObjectivesFarmers' health outcomes differ from that of the general population regarding several major diseases. In this study, we investigate associations of physical activity at work with lipid concentrations measured pre‐diagnostically in another study performed in Norwegian farmers, to assess if the beneficial effect of physical work is partly mediated via serum lipid levels.

MethodsFarmers according to the Norwegian agricultural censuses 1969–1989 and their spouses were identified in the Janus Serum Bank and in files of different screening health investigations of Norwegian counties 1974–1987. We identified 284 persons who gave information on diet habits and physical activity and from whom we already had analysed serum for phospholipid fatty acid concentrations in a case‐control study of colorectal cancer. We assessed associations between diet, physical activity at work (four levels) and levels of fatty acids, controlling for case status, sex, age and status (farm holder or spouse).

ResultsCompared to work activity level 1, level 4 activity increased the EPA (20:5 n‐3) level by 6 μg/l serum (95% CI 0.2 to 12 μg/l). Work levels 3 and 4 increased the arachidonic acid (20:4 n‐6) levels by 14 (3 to 25) and 6 μg/l (−4 to +16), respectively. For DHA (22:6 n‐3), saturated fatty acids and oleic acid, no associations were found. Separate analysis of cases and controls from the case‐control study showed the same size and direction of associations, as did separate analysis by sex. The effect size on EPA comparing physical work level 4 with level 1 equalled the difference of 7 units on the indicator scale of fish eating (the range of this scale was 21 units from lowest to highest fish consumption).

ConclusionPositive health effects from physical activity at work may possibly result partly from changes in the lipid profiles and not only by direct effects on target organ systems of the related diseases.

Key wordsfarmers work; physical exertion; lipid profiles

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

J. Rusiecki1, R. Patel1, A. Blair2, M. Dosemeci2, J. Hoppin3, M. Alavanja2. 1Uniformed Services University; 2Division of Cancer Epidemiology and Genetics, National Cancer Institute; 3National Institute of Environmental Health Sciences

ObjectivesPermethrin, a broad‐spectrum, pyrethroid insecticide, is one of the most widely used pesticides on crops (eg, cotton, wheat, corn, vegetables) and animals. Many household sprays, pet flea sprays, and ornamental garden and turf products contain permethrin. Permethrin is part of the Department of Defense Insect Repellent System that currently treats all battle dress uniforms with permethrin. We investigated site‐specific cancer incidence and risk among pesticide applicators exposed to permethrin in the Agricultural Health Study.

MethodsWe obtained detailed pesticide exposure information from 57 311 licensed pesticide applicators in Iowa and North Carolina using a self‐administered questionnaire completed at the time of enrolment (1993–1997). Cancer incidence was followed through December 31, 2004. We used Poisson regression to calculate rate ratios (RRs) and 95% confidence intervals (CIs) for various cancers, adjusting for potential confounders. We evaluated permethrin use via two exposure metrics: tertiles of lifetime days of exposure (LD) and of intensity‐weighted lifetime days of exposure (IWLD, which incorporates a measure of exposure intensity).

Results12 236 (21%) of the AHS applicators reported ever using permethrin. Exposure was not associated with overall cancer incidence, or with most cancer sites. Applicators in the highest tertiles of LD and IWLD had non‐statistically significant, moderately elevated risks for all lymphatic and haematopoietic cancers (LD: RR 1.67, 95% CI 0.81 to 3.42, p‐trend = 0.16; IWLD: RR 1.37, 95% CI 0.62 to 3.04, p‐trend = 0.44) when compared to applicators in the lowest tertiles. Among this group of cancers, only multiple myeloma showed an excess where we found elevated risks for the highest tertiles of LD (RR 4.9, 95% CI 1.32 to 18.23, p‐trend = 0.05) and IWLD (RR 4.77, 95% CI 0.94 to 24.11, p‐trend = 0.04) compared to the lowest tertiles; we were unable to evaluate other haematopoietic cancers because of small numbers.

ConclusionThe findings for lymphatic and haematopoietic cancers as a group, and in particular multiple myeloma, were intriguing and will require longer follow‐up time in order to evaluate further.

Key wordspesticide; cancer; permethrin


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