Publications (27) View all
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Article: Agricultural pesticide management in Thailand: status and population health risk
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ABSTRACT: As an agricultural country and one of the world's major food exporters, Thailand relies heavily on the use of pesticides to protect crops and increase yields. During the past decade, the Kingdom of Thailand has experienced an approximate four-fold increase in pesticide use. This increase presents a challenge for the Royal Thai Government in effectively managing and controlling pesticide use based upon the current policies and legal infrastructure. We have reviewed several key components for managing agricultural pesticides in Thailand. One of the main obstacles to effective pesticide regulation in Thailand is the lack of a consolidated, uniform system designed specifically for pesticide management. This deficit has weakened the enforcement of existing regulations, resulting in misuse/overuse of pesticides, and consequently, increased environmental contamination and human exposure. This article provides a systematic review of how agricultural pesticides are regulated in Thailand. In addition, we provide our perspectives on the current state of pesticide management, the potential health effects of widespread, largely uncontrolled use of pesticides on the Thai people and ways to improve pesticide management in Thailand.Highlights► We review the legal instruments enacted to manage pesticides in Thailand. ► Thailand lacks a consolidated, uniform system for pesticide management. ► An inability to enforce existing regulations leads to increased pesticide exposure. ► We provide our perspectives on ways to improve pesticide management in Thailand.Environmental Science & Policy 03/2012; 17:72-81. · 3.02 Impact Factor -
Article: Development and application of an indirect competitive enzyme-linked immunosorbent assay for the detection of p,p'-DDE in human milk and comparison of the results against GC-ECD.
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ABSTRACT: 1,1-Dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p'-DDE) is the major metabolite of insecticide 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT) and a persistent organic pollutant (POPs) with concerns regarding its bioaccumulation and persistence in the environment and food chain. In the present study, an indirect competitive enzyme-linked immunosorbant assay (ic-ELISA) specific for the detection of p,p'-DDE is described. In hapten synthesis, 2,2'-bis(4-chlorophenyl)ethanol and glutaric anhydride were used as precursor and spacer arm, respectively. The hapten was then conjugated to bovine serum albumin (BSA) as immunogen for mouse immunization and also conjugated to ovalbumin as coating antigen for ELISA. The developed ic-ELISA was used for detecting p,p'-DDE in human milk samples and validated against the results from conventional gas chromatography-electron capture detection (GC-ECD). Coefficients of variation (%CV) of ELISA were 5.7-10.4% for intra-assay and 10.6-19.6% for interassay variations. The Pearson correlation coefficient of p,p'-DDE concentrations between ic-ELISA and GC-ECD was r = 0.766, which was in an acceptable range. The results indicate that the developed assay could be an alternative analytical tool for monitoring p,p'-DDE in lipimic matrices such as human milk.Journal of Agricultural and Food Chemistry 11/2011; 60(1):16-22. · 2.82 Impact Factor -
Article: Production of monoclonal antibody to acaricide dicofol and its derivatives.
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ABSTRACT: In Thailand detection of acaricide dicofol residues has been sporadically performed due to the limitation of analytical techniques. Conventional analytical methods for detecting dicofol residues most often use chromatographic-based techniques. Our ultimate aim is to develop an alternative method for rapidly analyzing dicofol residues in vegetables and fruit samples. Here we report the production of monoclonal antibodies specific to dicofol and its derivatives. Hapten-protein carriers were prepared by linking succinic anhydride to dichlorobenzhydrol (DCBH), which was then conjugated to bovine serum albumin (BSA) and oval albumin (OVA). DCBH-BSA conjugate was used as immunogen while DCBH-OVA conjugate was used as capture antigen for competitive inhibition assay. Female BALB/c mice were immunized with DCBH-BSA conjugate subcutaneously, and antibody (Ab) level was determined 2 weeks after the last immunization. Spleen cells producing high titer antibody were isolated and fused with myeloma cells of P3.X6.Ag8.653. After limiting dilutions, antibody produced by one clone had high affinity, which was found to be of IgG1 with κ light chain. Specificity and inhibition concentrations of the monoclonal antibody (MAb) were determined by competitive indirect ELISA with dicofol, and its 50% (IC(50)) was 0.28 μg/mL. Working ranges of the developed immunoassay were from 0.07 to 25 μg/mL. Hence, the prepared MAb will be able to be applied for immunoassay development for detecting dicofol residue in vegetables and fruits far below the maximum residue limit such that 5 g of fruits and berries can be detected below 0.1 mg/kg.Hybridoma (2005) 12/2010; 29(6):495-500. · 0.42 Impact Factor -
Article: Polymethoxylated flavones, flavanone glycosides, carotenoids, and antioxidants in different cultivation types of tangerines ( Citrus reticulata Blanco cv. Sainampueng) from Northern Thailand.
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ABSTRACT: Polymethoxylated flavones (PMFs) and flavanone glycosides (FGs) were analyzed in hand-pressed juice and the peeled fruit of 'Sainampueng' tangerines ( Citrus reticulata Blanco cv. Sainampueng) grown in northern Thailand. The tangerines were collected from a citrus cluster of small orchard farmers and were cultivated as either agrochemical-based (AB), agrochemical-safe (AS), or organic grown fruits. Juice samples were also measured on contents of carotenoids, ascorbic acid, and tocopherols. The peel-deriving PMFs tangeretin, nobiletin, and sinensetin were found with high concentrations in juice as a result of simple squeezing, whereas amounts of those PMFs were negligibly low in peeled tangerine fruit. In contrast, the mean concentrations of the FGs narirutin, hesperidin, and didymin were several fold higher in peeled fruit than in tangerine juice and significantly higher in organic than AS and AB tangerines. Narirutin and hesperidin in juice from organic produces as well as narirutin in juice from AS produces were significantly higher than respective mean concentrations in juice from AB produces. beta-Cryptroxanthin was the predominant carotenoid beside zeaxanthin, lutein, lycopene, and beta-carotene in tangerine juice. Ascorbic acid concentrations were not predicted by the type of cultivation, whereas alpha-tocopherol was significantly higher in juice from organic than AS produces. In summary, hand-pressed juice of C. reticulata Blanco cv. Sainampueng serves as a rich source of PMFs, FGs, carotenoids, and antioxidants: 4-5 tangerine fruits ( approximately 80 g of each fruit) giving one glass of 200 mL hand-pressed juice would provide more than 5 mg of nobiletin and tangeretin and 36 mg of hesperidin, narirutin, and didymin, as well as 30 mg of ascorbic acid, >1 mg of provitamin A active beta-cryptoxanthin, and 200 microg of alpha-tocopherol.Journal of Agricultural and Food Chemistry 05/2010; 58(10):6069-74. · 2.82 Impact Factor -
Article: Urinary paranitrophenol, a metabolite of methyl parathion, in Thai farmer and child populations.
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ABSTRACT: Human exposure to methyl parathion can be assessed by measuring the concentration of its metabolite paranitrophenol (PNP) in urine. Our biologic monitoring study in Chiang Mai, Thailand, measured PNP and dialkylphosphate metabolites (i.e., dimethylphosphate [DMP] and dimethylthiophosphate [DMTP]) of methyl parathion in urine samples collected from 136 farmers (age 20 to 65 years) and 306 school children (age 10 to 15 years) in 2006. Participants came from two topographically different areas: one was colder and mountainous, whereas the other was alluvial with climate fluctuations depending on the monsoon season. Both children and farmers were recruited from each area. Despite methyl parathion's prohibited use in agriculture in 2004, we detected PNP in >90% of all samples analyzed. We applied a nonparametric correlation test (PNP vs. DMP and DMTP) to determine whether the PNP found in most of the samples tested resulted from exposures to methyl parathion. DMP (Spearman's rho = 0.601 [p = 0.001] for farmers and Spearman's rho = 0.263 [p <0.001] for children) and DMTP (Spearman's rho = 0.296 [p = 0.003] for farmers and Spearman's rho = 0.304 [p<0.001] for children) were positively correlated with PNP, suggesting a common source for the three analytes, presumably methyl parathion or related environmental degradates. Although we found a modest correlation between the metabolites, our findings suggest that despite the prohibition, at least a portion (approximately 25% to 60%) of the PNP detected among farmers and children in Thailand may be attributed to exposure from continued methyl parathion use.Archives of Environmental Contamination and Toxicology 04/2009; 57(3):623-9. · 1.93 Impact Factor
