Multiple Pesticide Exposure and Chromosome Aberrations Among Orange Farmers From Northern Thailand

Abstract

SM1-PD-01 Session Title: Pesticides and Persistant Organic Pollutants Introduction: Farmers are prone to multiple pesticide exposure especially in an intensive agriculture. In northern Thailand, growing of mandarin oranges has been increasing rapidly may be due to suitable geographic condition. We conducted a prospective study in orange farmers on pesticide exposure and its effect from Chiang Mai Province in 2004 to 2005. Methods: Fifty family farmers (F1 and F2) and 2 consumer groups, as referent groups, were enrolled. One consumer group was from the same districts of farmers (C1, n = 68) and the other was from Chiang Mai City (C2, n = 54). Farmers and consumers were followed for 3 and 2 visits (V1, V2, and V3) in approximately 6-month intervals, respectively. Demographic data were collected using structured questionnaires. Venous blood samples (~10 mL) were collected for acetylcholinesterase (AChE) in red cells, organochlorine pesticides (OCPs) in plasma, and chromosome aberrations (CAs) in lymphocytes. AChE activity was assayed using Ellman-based method, OCPs using a Prapamontol and Stevenson method, and CAs in lymphocytes using a WHO standard method. Results: Farmers (F1 males and F2 females) from 27 to 60 years of age and consumers (C1, and C2, both sexes) 24 to 62 years of age. Inhibitions of F1 and F2 AChE activities in V2 versus V1 were 37.1% and 32.9% (both, P < 0.001) and in V3 versus V1 were 38.6% and 36.2% (both, P < 0.001), respectively. Inhibitions of AChE activities of C1 and C2 in V2 versus V1 were 26.3% (P < 0.001) and 7.13% (not significant), respectively. Two major OCP components detected were p,p'-DDE (100%) and p,p'-DDT (98%–100%) except in C2 was only 1.85%. Geometric means of p,p'-DDE in F1, F2, C1, and C2 were 21.0, 21.9, 13.7, and 7.78 ng/mL and of p,p'-DDT were 1.82, 1.95, 0.84, and 0.26 ng/mL, respectively. CA was performed in 2 visits. Percentage of CAs in F1, V1 versus V3 were 1.42 ± 1.26 versus 2.00 ± 1.26 (P = 0.03) and in F2, V1 versus V3 were 1.22 ± 1.43 versus 1.98 ± 1.87 (P = 0.03). Percentage of CAs in C1, V1 versus V2 were 1.50 ± 1.32 versus 2.41 ± 1.85 (P = 0.001) and in C2, V1 versus V2 were 1.35 ± 1.25 versus 1.30 ± 1.28 (not significant). Discussion and Conclusions: AChE activities of F1, F2, and C1 showed significantly and consistently inhibition pattern. Levels of p,p[r]'-DDE and p,p'-DDT in farmers were significantly higher than in consumers. Farmers and C1 therefore could be exposed to cholinesterase-inhibiting pesticides and OCPs. Percentage of CAs in farmers and C1 were significantly increased but not in C2. This may be the cytogenetic effect consequences from multiple pesticide exposure, although confounding factors such as age, sex, education, and chronic ill health should not be ignored.