2.1 Research design
The present study was a descriptive survey to investigate the general characteristics, exposure to pesticides, depression, and the level of lower urinary tract symptoms among male farmers.
2.2 Subjects And Procedure
A survey and medical examination were conducted among 864 farmers (475 men and 389 women) who participated in a physical examination at the Farmer’s Health and Safety Center of Dankook University from 2014 to 2015. A survey was also conducted on 532 facility cultivation farmers (264 men and 268 women) in Gongju-si in 2014 and 332 (211 men and 121 women) apple growers in Yesan-gun in 2015. The subjects agreed to participate in the study through a prior notice. A total of 348 men who responded that they were full-time farmers, took urine test related to pesticide exposure, and sincerely responded to a questionnaire related to pesticide exposure, depression, and lower urinary tract symptoms were included. The general characteristics, level of pesticide exposure, prostate symptoms of the subjects were assessed through one-to-one interviews using a structured questionnaire. Survey agents who received standardization training helped farmers who were mostly of old age to answer the questionnaire.
2.3 Research Variables
2.3.1 General characteristics
Subjects’ general characteristics included age, body mass index (BMI), smoking, alcohol consumption, exercise level, chronic disease, and diagnosis of BPH. Ages were grouped into under 50, 50–59, 60–69, 70–79, and 80 years or older. Based on WHO criteria, BMI was classified into underweight (BMI < 18.5), normal (18.5 ≤ BMI ≤ 22.9), overweight (23 ≤ BMI ≤ 24.9), obesity (25 ≤ BMI ≤ 29.9), and severe obesity (BMI ≥ 30) 21. Farmers who were diagnosed with one or more of the four major diseases of hypertension, hyperlipidaemia, stroke, and angina were defined as “chronic disease.” The farmers were determined to be diagnosed with BPH based on “yes” or “no” answer to a question asking whether they had been diagnosed with BPH in the self-administered questionnaire and the proportion of BPH was 7.2% in this study.
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Pesticide Symptoms
The authors defined ‘pesticide symptoms’ as a symptom which the participant experienced among 21 clinical symptoms provided in the questionnaire within 48 hours after exposure to pesticides over the last 1 year 22 and the authors classified into 3 categories depending on the number of symptoms (0, 1–2, ≥ 3). The 21 clinical symptoms included ‘skin irritation, dizziness, nausea, fatigue, headache, eye irritation, vomiting, sore throat, chest pain, runny nose, excessive sweating, paresthesia, hyperactivity (anxiety), muscle weakness, lacrimation, diarrhea, dyspnea, blurred vision, slurred speech, paralysis, and syncope’. 22–25 Pesticide symptoms was based on WHO.26
2.3.3 Depression
The Center for Epidemiological studies-Depression Scale (CES-D) is a self-rating depression scale and easy to use in epidemiological studies because items are very simple and severity is measured based on the duration of the symptom 27. The CES-D was also standardized in South Korea in 1993 28. To measure subjects’ level of depression, the Korean version of CES-D, a self-report scale, was used. The scale consists of a total of 20 items on a 3-point Likert scale from “very rare” for zero point to “mostly did” for three points. Positive items were inversely scored, and depression was diagnosed if the score was 16 points or higher out of a total of 60 points.28
2.3.4 Pesticide Exposure
Four organophosphorus pesticides including DiMethylPhosphate (DMP), DiMeThylthioPhosphate (DMTP), DiEthylPhosphate (DEP), and DiEthylThiophosphate (DETP), and four pyrethroid pesticide metabolites including (Cis-2,2-(dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid(Cis-DCCA), Trans-2,2-(Dichlorovinyl)-2,2-dimethylCyclopropane Carboxylic Acid (Trans-DCCA), 3-PhenoxyBenzoic Acid(3-PBA), and Cis-2,2-(dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (DBCA) were analysed. Frozen urine samples were taken out and thawed for 30 minutes, centrifugated, and the supernatant was used for analysis. Quantitative analysis was performed to determine metabolite concentration in the sample using a gas chromatograph-mass spectrometer (GC/MS). Hewlett-Packard (HP) 5890 GC connected via a direct interface with HP 7673A autosampler for sample injection were used for samples collected in 2014. For samples collected in 2015, AG 7693 autosampler connected via a direct interface to Agilent Technologies (AG) 7000C GC/MS Triple Quad was used. To draw the calibration curve and to determine the recovery rate and detection limit, newborn urine was used as blank and confirmed that it did not have any of the metabolites of interest before the analysis. Schatten analysis method was used without modification for organophosphorus metabolites.29
Four pyrethroid metabolites (Cis and trans-3-(2-2dichlorovinyl)-2, 2-dimethylcyclopropane carboxylic acid (Cis-DCCA, Trans-DCCA), 3-phenoxybenzoic acid (3-PBA), and Cis-3-(2-2dibrmovinyl)-2, 2-dimethylcyclopropane carboxylic acid (DBCA) were selected and for analysis Uey ama method was used without modification 30. The LOD of the samples in 2014 was Cis-DCCA 1.0 µg/L, trans-DCCA 1.0 µg/L, 3-PBA 0.5 µg/L, and DBCA 1.0 µg/L, and the LOD of the samples in 2015 was Cis-DCCA 0.5 µg/L, trans-DCCA 0.5 µg/L, 3-PBA 0.3 µg/L, and DBCA 0.5 µg/L.
All eight metabolites were corrected with urine creatinine, and if the values were lower than the values of LOD, the values were replaced with the values obtained by dividing LOD with the square root of two.30 For the replacement of organophosphorus and pyrethroid metabolites, the four metabolites of each group were summed to obtain the total exposure values of organophosphorus and pyrethroid pesticides, and the two values were divided by the urine creatinine value of each subject, and the three fractiles of the values were used in the analysis.
The median of the organophosphate metabolite was DMP 0.0004 µg/ g crea, DMTP 0.0026 µg/ g crea, DEP 0.0004 µg/ g crea, and DETP 0.0033 µg/ g crea. The median of the pyrethroid metabolite was Cis-DCCA 0.0080 µg/ g crea, trans-DCCA 0.0108 µg/ g crea, 3-PBA 0.0243 µg/ g crea, and DBCA 0.0058 µg/g crea. One, two, and three fractiles of organophosphorus metabolites in urine were ≤ 0.02 µg/g crea, 0.03–0.22 µg/g crea, and ≥ 0.23 µg/g crea, respectively, and three fractiles of pyrethroid metabolites in urine were ≤ 0.03 µg/g crea, 0.04–0.10 µg/g crea, and ≥ 0.11 µg/g crea, respectively.
2.3.5 Lower Urinary Tract Symptoms
For lower urinary tract symptoms, the Korean version of the International Prostate Symptoms Score (IPSS) was used.31 The scale measures seven symptoms including the sensation of residual urine, frequent urination, intermittent urination, urinary urgency, weak stream, urinary hesitancy, and night urination, and the score for each symptom was from zero point for “Not at all” to five points for “Always”.31 The total score was 35 points and symptoms were classified into minor, moderate and severe symptoms for scores 0–7, 8–19 and 20–35, respectively.32 In the present study, low urinary tract symptom group was defined as IPSS score eight points or higher as in a previous study and subjects were classified into “non- symptom group” and “symptom group” .32
2.4 Data Analysis
The collected data were analysed using SPSS 22.0 program. The general characteristics, pesticide exposure, and lower urinary tract symptoms of the subjects were analysed using chi-squared test and p for trend test. To determine if lower urinary tract symptoms vary depending on pesticide concentration, Mann-Whitney test was performed. A nonparametric test was used because the data distributions of age, depression scale, the metabolites of organophosphorus and pyrethroid pesticides were not normal. To identify the factors that affect lower urinary tract symptoms, multivariable logistic regression analysis was performed, and the significance level for all analyses was set at p < 0.05.