Urinary paranitrophenol, a metabolite of methyl parathion, in Thai farmer and child populations

Pesticide use in Thailand: Current situation, health risks, and gaps in research and policy

Agriculture in Thailand, which employs over 30 percent of the workforce and contributes significantly to the country's gross domestic product, is a key sector of its economy. Import and use of pesticides has increased over the past decade due to Thailand's major role as a leading exporter of food and agricultural products. The widespread and poorly regulated use of pesticides presents a potential risk to the health of farmers, farm families, the general population including children and the environment. This article is a result of the Southeast Asia GEOHealth Network Meeting of February 2019. It summarizes the current situation on pesticide use and regulation in Thailand and reports research findings on the potential health and environmental impacts of pesticide use, as well as highlighting gaps in research that could play an important and influential role in future policy initiatives on pesticides. Although Thailand has made remarkable progress in improving agricultural health and safety and similarly strong research and policy programs are being developed in other countries in the region, there are still significant gaps in research and policy that need to be filled.

Pesticide exposure among students and their families in Nova Friburgo, Rio de Janeiro

Farming is a risky occupation, especially family farming in developing country. The occupational hazards commonly used in such activity could affect all family members, including children and adolescents. This study describes the pattern of pesticide exposure among students and their families from a farming region located in Nova Friburgo, State of Rio de Janeiro, Brazil. Sociodemographic characteristics, habits, working practices and the degree of exposure to pesticides were assessed by a questionnaire. Our study population consisted of students and family members of both sexes, aged between 6 and 85 years old (N = 352) being 167 women and 185 men. There was a predominance of participants between 10-19 years (71.3%), singles (77.5%), and most had not completed primary education (54.5%). In terms of occupation, 45.5% reported to be farmers and 39.6% were students. The variables mostly associated with pesticide exposure were sex (p < 0.001), educational level (p < 0.001), and being a farmer (p < 0.001). Our results showed that children and teenagers seemed to have the same degree of exposure to pesticides as the adults. Our findings also suggest that sex, occupation and educational level, despite teachers were included, are directly associated with degree of exposure.

Children's Environmental Health in Thailand: Past, Present, and Future

Background:

There is increasing evidence of a link between environmental pollution and preventable diseases in developing countries, including Thailand. Economic development has generated several types of pollution that can affect population health. While these environmental health effects can be observed throughout life, pregnant women and children represent particularly vulnerable and sensitive groups.

Methods:

The published epidemiological literature investigating environmental chemical exposure in Thai children was reviewed, highlighting those that investigated associations between exposure and subsequent health outcomes.

Results:

The majority of the Thai epidemiological studies on environmental health in children were cross-sectional in design, with some demonstrating associations between exposure and outcome. The three main types of chemical exposure in Thai children were pesticides, heavy metals, and air pollution, which resulted from agricultural activities in countryside areas, industrial zones (both registered and unregistered establishments), mining, and traffic in inner cities. Major health outcomes included detrimental effects on cognitive function and cancer risk. Pesticide exposure was focused on, but not limited to, agricultural areas. The success of the Thai environmental policy to introduce lead–free petrol can be demonstrated by the decline of mean blood lead levels in children, particularly in urban areas. However, unregistered lead-related factories and smelters act as hidden sources. In addition, there is increasing concern, but little acknowledgement, about the effects of chronic arsenic exposure related to mining. Lastly, air pollution remains a problem in both dense city populations due to traffic and in rural areas due to contamination of indoor air and house dust with heavy metals, endotoxins and other allergens.

Conclusions:

The increasing number of published articles demonstrates an improved awareness of children’s environmental health in Thailand. Chemical hazards, including the improper use of pesticides, environmental contamination with heavy metals (lead and arsenic), and air pollution in inner cities and indoor air, continue to be growing issues.

Occupational health and safety for agricultural workers in Thailand: gaps and recommendations, with a focus on pesticide use

Over 16.7 million workers in Thailand (42 percent of the working population) are engaged in agriculture, disproportionately from the lower socioeconomic strata of Thai society. Most agricultural workers (over 93 percent) work in the informal sector without the protections of regulations or enforcement of labor or health and safety laws or enrollment in a social security system. Although Thailand's use of herbicides, fungicides, and insecticides is growing, there is little regulation of the sale, use, or application of these potentially toxic chemicals. This paper summarizes the research to date on occupational health and safety for Thai agricultural workers, identifies gaps in pesticide regulations and the current systems for occupational health and safety and social support for Thai agricultural workers, and makes recommendations for future policy and research initiatives to fill the identified gaps.

Distribution and determinants of urinary biomarkers of exposure to organophosphate insecticides in Puerto Rican pregnant women

Globally, human exposures to organophosphate (OP) insecticides may pose a significant burden to the health of mothers and their developing fetuses. Unfortunately, relevant data is limited in certain areas of the world concerning sources of exposure to OP insecticides in pregnant populations. To begin to address this gap in information for Puerto Rico, we studied repeated measures of urinary concentrations of 10 OP insecticide metabolites among 54 pregnant women from the northern karst region of the island. We also collected demographic data and self-reported information on the consumption of fruits, vegetables, and legumes in the past 48 h before urine collection and home pest-related issues. We calculated the distributions of the urinary biomarkers and compared them to women of reproductive age from the general U.S. population. We also used statistical models accounting for correlated data to assess within-subject temporal variability of the urinary biomarkers and to identify predictors of exposure. We found that for all but two metabolites (para-nitrophenol [PNP], diethylthiophosphate [DETP]), 50th or 95th percentile urinary concentrations (the metric that was used for comparison was based on the biomarker's detection frequency) of the other eight metabolites (3,5,6-trichloro-2-pyridinol [TCPY], 2-isopropyl-4-methyl-6-hydroxy-pyrimidine, malathion dicarboxylic acid, diethylphosphate, diethyldithiophosphate, dimethylphosphate, dimethylthiophosphate [DMTP], dimethyldithiophosphate) were somewhat lower in our cohort compared with similarly aged women from the continental United States. TCPY, PNP, DETP, and DMTP, which were the only urinary metabolites detected in greater than 50% of the samples, had poor reproducibility (intraclass correlation coefficient range: 0.19-0.28) during pregnancy. Positive predictors of OP insecticide exposure included: age; marital or employment status; consumption of cherries, grape juice, peanuts, peanut butter, or raisins; and residential application of pesticides. Further research is needed to understand what aspects of the predictors identified influence OP insecticide exposure during pregnancy.

Pesticide residue transfer in Thai farmer families: using structural equation modeling to determine exposure pathways

Use of pesticides in agriculture may lead to downstream exposure of farmers' families to pesticide residues inadvertently taken home. Identification of the independent contribution of different exposure pathways from the farmer to their children can provide clear targets to reduce exposure of farmers' children. Individual contributions of different pesticide transfer exposure pathways were investigated using structural equation modeling methods, and the benefits of these methods compared to standard multiple regression are described. A total of 72 Thai families, consisting of a farmer, a spouse, and a child, participated in this study. Family members completed a questionnaire and self-collected three spot morning urine samples in the spraying season. Urine samples were analyzed for diethyl phosphate, diethyl thiophosphate, diethyl dithiophosphate, dimethyl phosphate, dimethyl thiophosphate, and dimethyl dithiophosphate. A path model was developed based on an a priori hypothesized framework to examine the individual contributions of different exposure pathways that may directly or indirectly affect transfer of pesticide residues from farmers to their children. Transfer from the farmer to the child occurs indirectly, primarily through transfer to the spouse in the first instance, but also through contamination of the home environment. Clear targets for interventions are directly the reduction of farmers' take-home exposures and indirectly frequent cleaning of the home to avoid buildup of pesticide residues.

Parathion hydrolysis revisited: in situ aqueous kinetics by (1)h NMR

The kinetics of parathion (PTH) decomposition into para-nitrophenolate (pNP) and O,O-diethylthiophosphate (DETP) were measured in high-pH aqueous solutions at 20 °C by proton nuclear magnetic resonance spectroscopy ((1)H NMR). Reaction rates were determined over a 16 h observation time, in solutions with NaOD concentrations of 5.33 mM, 33.33 mM, and 100 mM, with NaCl added to fix ionicity. The pseudo-first-order rate constants for these systems were determined to be 1.9 × 10(-4) min(-1), 1.4 × 10(-3) min(-1), and 3.8 × 10(-3) min(-1) respectively. The slope of the linear plot of these rates against OD(-) concentration yielded the second-order hydrolysis rate constant 3.90 × 10(-5) mM(-1) min(-1), valid over this pH range from 10.5 to 13. The data agree with some, and contradict other, earlier work. Our fitting procedure included background levels and allowed us to not only obtain reliable kinetic results but also to measure residual pNP and DETP impurity levels.

Agricultural Pesticide Management in Thailand: Situation and Population Health Risk

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.

Thionate versus Oxon: comparison of stability, uptake, and cell toxicity of ((14)CH(3)O)(2)-labeled methyl parathion and methyl paraoxon with SH-SY5Y cells

The stability, hydrolysis, and uptake of the organophosphates methyl parathion and methyl paraoxon were investigated in SH-SY5Y cells. The stabilities of ((14)CH(3)O)(2)-methyl parathion ((14)C-MPS) and ((14)CH(3)O)(2)-methyl paraoxon ((14)C-MPO) at 1 microM in culture media had similar half-lives of 91.7 and 101.9 h, respectively. However, 100 microM MPO caused >95% cytotoxicity at 24 h, whereas 100 microM MPS caused 4-5% cytotoxicity at 24 h ( approximately 60% cytotoxicity at 48 h). Greater radioactivity was detected inside cells treated with MPO as compared to MPS, although >80% of the total MPO uptake was primarily dimethyl phosphate (DMP). Maximum uptake was reached after 48 h of (14)C-MPS or (14)C-MPO exposure with total uptakes of 1.19 and 1.76 nM/10(6) cells for MPS and MPO, respectively. The amounts of MPS and MPO detected in the cytosol after 48 h of exposure time were 0.54 and 0.37 nM/10(6) cells, respectively.