Effects of urinary of organophosphate metabolites on nerve conduction and neurobehavioral performance among farmers in northern Thailand.

Farmers are regarded as a high-risk population for pesticide exposure because of the frequency of their occupational exposure to organophosphate (OP) pesticides. The purposes of this study were 1) to compare urinary OP metabolites, nerve conduction, and neurobehavioral (NB) performance between farmers and a control group, as well as between baseline measurement and after spraying OP pesticides; 2) to investigate the factors associated with increased urinary OP metabolites after spraying OP pesticides; and 3) to investigate the effects of OP metabolites on changes in nerve conduction and NB performance after spraying OP pesticides. This study was conducted with a sample size of 71 farmers and a control group of 26. The findings showed that after spraying OP pesticides total dialkylphosphate (DAP) levels were significantly higher than baseline levels. Multiple linear regression showed that increased urinary OP metabolites among farmers after spraying pesticides were negatively associated with wearing a mask when spraying OP pesticides and positively associated with the number of years of farm work and type of sprayer equipment. The results also showed a positive association between the increased urinary total diethylphosphate (DEP) levels and the decreased amplitude of motor nerve conduction. Furthermore, a positive correlation was observed between increased urinary total DEP and decreased right amplitude of sympathetic skin response (SSR). An increase in urinary total DMP was positively associated with a decrease in raw score and a standard score of visual-motor integration (VMI). Our findings provide evidence that exposure to OP pesticides can cause a deficit in nerve conduction and NB performance in farmers. These findings may contribute to the early detection of neurological disease and inform strategies to prevent damage to the peripheral and central nervous systems.

The reliability of neurobehavioral tests in a thai adult population / A confiabilidade dos testes neurocomportamentais em uma população adulta tailandesa

ABSTRACT Early detection of decline in neurobehavioral (NB) performance requires reliable methods of testing. Although NB tests have been shown to be consistent and reliable in Western countries, there has been limited research in Asian populations. Objective: The purpose of this study was to investigate the test-retest reliability of NB tests in a Thai adult population and examine the impact of demographic data on NB tests. The aspects of the tests chosen were memory, attention, hand-eye coordination, motor speed, and dexterity. Methods: The three NB tests used were digit span, Purdue Pegboard, and visual-motor integration. All three were administered to a population of 30 Thai adults. Results: The outcomes of all Pearson's correlation coefficient tests (r) were positive and greater than 0.60, and subtest-retest reliability correlation coefficients ranged from 0.63 (p<0.001) to 0.81 (p<0.001). Interestingly, the outcomes of all of these tests were not affected by demographic data, with the exception of the Purdue Pegboard test, in which performance on the preferred hand and both hands assessment was weakly associated with age (β=-0.09, p<0.001 and β=-0.08, p<0.05, respectively). Conclusions: NB tests have adequate reliability and are useful for the evaluation of clinical memory, attention, hand-eye coordination, motor speed, and dexterity in Thai adults. These tests were not affected by demographic data. However, further studies to measure the validity of the digit span, Purdue Pegboard, and visual-motor integration tests are needed.

RESUMO A detecção precoce do declínio no desempenho neurocomportamental (NC) requer métodos confiáveis de teste. Embora os testes NC tenham se mostrado consistentes e confiáveis em países ocidentais, as pesquisas em populações asiáticas ainda são limitadas. Objetivo: O objetivo deste estudo foi investigar a confiabilidade de teste-reteste dos testes NC em uma população adulta tailandesa e o impacto dos dados demográficos nos testes NC. Os aspectos dos testes escolhidos foram memória, atenção, coordenação óculo-manual, velocidade motora e destreza. Métodos: Os três testes RC utilizados foram o digit span, o Purdue Pegboard e a integração visomotora. Todos os três foram usados em uma população de 30 adultos tailandeses. Resultados: Os resultados de todos os testes de coeficiente de correlação de Pearson (r) foram positivos e superiores a 0,60, e os coeficientes de correlação de confiabilidade subteste-reteste variaram de 0,63 (p<0,001) a 0,81 (p<0,001). Curiosamente, os resultados de todos esses testes não foram afetados pelos dados demográficos, com exceção do teste Purdue Pegboard, no qual o desempenho na mão preferida e a avaliação de ambas as mãos foi fracamente associado à idade (β=-0,09, p<0,001 e β=-0,08, p<0,05, respectivamente). Conclusão: Os testes NC apresentam confiabilidade adequada e são úteis para avaliação da memória clínica, atenção, coordenação óculo-manual, velocidade motora e destreza em adultos tailandeses. Esses testes não foram afetados por dados demográficos. No entanto, são necessários mais estudos para medir a validade dos testes de digit span, Purdue Pegboard e IVM.

Differences in Knowledge, Awareness, Practice, and Health Symptoms in Farmers Who Applied Organophosphates and Pyrethroids on Farms.

OBJECTIVE: This cross-sectional study aimed to examine farmers' knowledge, awareness, practices regarding pesticide use, and prevalence of health symptoms related to pesticides exposure among farmers who applied organophosphates (OP) and pyrethroids (PY). METHODS: Data regarding demographic variables and health symptoms pertinent to pesticide use was collected from 67 farmers who applied OP and 50 farmers who applied PY using interviews from January to March 2021. RESULTS: The farmers who applied OP had lower knowledge, awareness, and prevention practices regarding pesticide use than those who applied PY. After adjustment of covariate variables, the farmers who applied OP had a significantly higher prevalence of respiratory conditions (OR = 8.29 for chest pain, OR = 6.98 for chest tightness, OR = 27.54 for dry throat, and OR = 5.91 for cough), neurological symptoms (OR = 10.62 for fatigue and OR = 6.76 for paresthesia), and neurobehavioral symptoms (OR = 13.84 for poor concentration, OR = 3.75 for short term memory, and OR = 8.99 for insomnia) related to pesticide exposure than those who applied PY. CONCLUSION: Our findings suggest that OP had a more adverse effect on human health than PY, resulting in a higher prevalence of pesticide-related symptoms. The outcomes of this study have the benefit of providing vital information for all stakeholders with regard to the implementation of safe practices in the utilization of personal protective equipment (PPE) and pesticide use in a health intervention and health promotion program.

The reliability of neurobehavioral tests in a thai adult population.

Early detection of decline in neurobehavioral (NB) performance requires reliable methods of testing. Although NB tests have been shown to be consistent and reliable in Western countries, there has been limited research in Asian populations. Objective: The purpose of this study was to investigate the test-retest reliability of NB tests in a Thai adult population and examine the impact of demographic data on NB tests. The aspects of the tests chosen were memory, attention, hand-eye coordination, motor speed, and dexterity. Methods: The three NB tests used were digit span, Purdue Pegboard, and visual-motor integration. All three were administered to a population of 30 Thai adults. Results: The outcomes of all Pearson's correlation coefficient tests (r) were positive and greater than 0.60, and subtest-retest reliability correlation coefficients ranged from 0.63 (p<0.001) to 0.81 (p<0.001). Interestingly, the outcomes of all of these tests were not affected by demographic data, with the exception of the Purdue Pegboard test, in which performance on the preferred hand and both hands assessment was weakly associated with age (ß=-0.09, p<0.001 and ß=-0.08, p<0.05, respectively). Conclusions: NB tests have adequate reliability and are useful for the evaluation of clinical memory, attention, hand-eye coordination, motor speed, and dexterity in Thai adults. These tests were not affected by demographic data. However, further studies to measure the validity of the digit span, Purdue Pegboard, and visual-motor integration tests are needed.

A detecção precoce do declínio no desempenho neurocomportamental (NC) requer métodos confiáveis de teste. Embora os testes NC tenham se mostrado consistentes e confiáveis em países ocidentais, as pesquisas em populações asiáticas ainda são limitadas. Objetivo: O objetivo deste estudo foi investigar a confiabilidade de teste-reteste dos testes NC em uma população adulta tailandesa e o impacto dos dados demográficos nos testes NC. Os aspectos dos testes escolhidos foram memória, atenção, coordenação óculo-manual, velocidade motora e destreza. Métodos: Os três testes RC utilizados foram o digit span, o Purdue Pegboard e a integração visomotora. Todos os três foram usados em uma população de 30 adultos tailandeses. Resultados: Os resultados de todos os testes de coeficiente de correlação de Pearson (r) foram positivos e superiores a 0,60, e os coeficientes de correlação de confiabilidade subteste-reteste variaram de 0,63 (p<0,001) a 0,81 (p<0,001). Curiosamente, os resultados de todos esses testes não foram afetados pelos dados demográficos, com exceção do teste Purdue Pegboard, no qual o desempenho na mão preferida e a avaliação de ambas as mãos foi fracamente associado à idade (ß=-0,09, p<0,001 e ß=-0,08, p<0,05, respectivamente). Conclusão: Os testes NC apresentam confiabilidade adequada e são úteis para avaliação da memória clínica, atenção, coordenação óculo-manual, velocidade motora e destreza em adultos tailandeses. Esses testes não foram afetados por dados demográficos. No entanto, são necessários mais estudos para medir a validade dos testes de digit span, Purdue Pegboard e IVM.

Neurobehavioral effects of exposure to organophosphates and pyrethroid pesticides among Thai children.

The use of pesticides for crop production has grown rapidly in Thailand during the last decade, resulting in significantly greater potential for exposure among children living on farms. Although some previous studies assessed exposures to pesticides in this population, no studies have been conducted to evaluate corresponding health effects. Twenty-four children from a rice farming community (exposed) and 29 from an aquaculture (shrimp) community (control) completed the study. Participants completed a neurobehavioral test battery three times at 6 month intervals: Session I: preliminary orientation; Session II: high pesticide use season; Session III: low pesticide-use season. Only sessions II and III were used in the analyses. High and low pesticide use seasons were determined by pesticide use on rice farms. Urinary metabolites of organophosphates (OPs) and pyrethroids (PYR) were analyzed from first morning void samples collected the day of neurobehavioral testing. Rice farm participants had significantly higher concentrations of dialkylphosphates (DAPs) (common metabolites of OPs) and TCPy (a specific metabolite of chlorpyrifos) than aquaculture farm children during both seasons. But, TCPy was significantly higher during the low rather than the high pesticide use season for both participant groups. Rice farm children had significantly higher DCCA, a metabolite of PYR, than aquaculture participants only during the high exposure season. Otherwise, no significant differences in PYR metabolites were noted between the participant groups or seasons. No significant adverse neurobehavioral effects were observed between participant groups during either the high or low pesticide use season. After controlling for differences in age and the Home Observation for Measurement of the Environment (HOME) scores, DAPs, TCPy, and PYR were not significant predictors of adverse neurobehavioral performance during either season. Increasing DAP and PYR metabolites predicted some relatively small improvement in latency of response. However, due to the small sample size and inability to characterize chronic exposure, any significant differences observed should be regarded with caution. Moreover although not statistically significant, confidence intervals suggest that small to moderate adverse effects of pesticide exposure cannot be ruled out for some indicators of neurobehavioral performance.

Pyrethroid insecticide exposure in school-aged children living in rice and aquacultural farming regions of Thailand.

BACKGROUND: Pyrethroid insecticides (PYR) are commonly used in rice farms and household pest control in Thailand. No investigative study has yet been made regarding factors associated with PYR exposure among Thai children. OBJECTIVE: This study aimed to compare the levels of PYR exposure between children living in rice farms (high-intensity PYR used) and aquacultural areas (low-intensity PYR used) during the wet and dry seasons in Thailand, during which different amounts of PYR are applied. Environmental conditions and common activities of children were used to identify factors associated with PYR exposure. METHODS: A cross-sectional study was done during the wet and dry seasons, respectively. A total of 53 participants aged between 6 and 8 years old were recruited from rice farms and aquacultural areas. A parental-structured interview was used to gather information about PYR use, household environments, and participants' activities. First voided morning urine samples were collected for PYR urinary metabolites (ie, 3-phenoxybenzoic acid [3-PBA] and cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid [DCCA]) measurements. Hand wipe samples were collected during home visits, to measure PYR residues on the hands. RESULTS AND DISCUSSION: The concentrations of urinary PYR metabolites were not significantly different between participants who lived in rice farming and those who lived in aquacultural areas, during both wet and dry seasons. Both participant groups had slightly increased urinary PYR metabolites during the wet season compared with the dry season. The results from linear regression analysis revealed that some environmental conditions and activities or practices may be used to predict trends of PYR exposure. Frequency of PYR use in farms (ß=0.004) and households (ß=0.07), proximity to rice farms (ß=0.09), playing in rice farms (ß=0.11), and oral exposure from objects exposed to PYR (ß=0.08) were likely to be related to increased concentrations of PYR metabolites. These findings suggest that PYR use in rice farms and households may be significant sources of PYR exposure among children living in agricultural areas. However, a bigger sample size may be necessary in a subsequent study, to explore the association between long-term exposure to pesticide and its health effects on children.

Organophosphate pesticide exposure in school-aged children living in rice and aquacultural farming regions of Thailand.

Organophosphate pesticides (OPs) are widely used in agricultural sectors in Thailand. Previous studies have documented that children residing in agricultural areas have higher exposure to OPs than children living in other residential areas. The objective of this study was to quantify urinary biomarkers of OP exposure and determine the environmental conditions and activities that predict their levels among children living in Central Thailand farming regions. In October 2011, 53 6-8-year-old participants were recruited from Pathum Thani Province, Thailand. Twenty-four lived in rice farming communities at Khlong Luang District where OPs are the pesticides used frequently. Twenty-nine participants, living in aquacultural farming communities at Lum Luk Ka District where OPs are not used, were recruited to serve as controls for pathways of exposure (e.g., residential, dietary) other than occupational/paraoccupational exposures encountered in rice farming. Household environments and participants' activities were assessed using a parental structured interview. Urine samples (first morning voids) were collected from participants for OP urinary metabolite (i.e., dialkylphosphates [DAPs] and 3,5,6-trichloro-2-pyridinol [TCPy]) measurements. The levels of most urinary OP metabolites were significantly higher in participants who lived in a rice farming community than those who lived in an aquacultural farming community (P < .05). The results from linear regression analysis revealed that the frequency of OP application on rice farms (∑DAP: P = .001; TCPy: P = .001) and living in a rice farming community (∑DAP: P = .009; TCPy: P < .001) were significant predictors of urinary DAP metabolite levels in participants. Increasing TCPy levels were significantly related to proximity to rice farm (P = .03), being with parent while working on a farm (P = .02), playing on a farm (P = .03), and the presence of observable dirt accumulated on the child's body (P = .02). In conclusion, OP metabolite levels among children who live in rice farming communities were strongly influenced by farming activity, household environments, and child behaviors, suggesting that these are the primary pathways in which children living in these agricultural communities in Thailand were exposed to OPs.

Adaptation of a neurobehavioral test battery for Thai children.

BACKGROUND: Exposure to neurotoxicants is a world wide problem with significant health implications for child development. In spite of higher neurotoxicant exposures, many developing countries do not have established neuropsychological instruments. OBJECTIVE: This study evaluated the adaptation and reliability of a computer and examiner administered Behavioral Assessment and Research System (BARS) that includes tests of motor speed and dexterity, attention, memory, and visuospatial coordination for use in Thailand. MATERIAL AND METHODS: To assess test-retest and alternate form reliability, BARS was administered to 24 healthy, 6-8 year old urban Thai children during two testing sessions two weeks apart. A comparison group of 29 healthy, rural Thai children of similar age and sex completed the BARS as part of another study and comprised a comparison group. RESULTS: Test-retest reliabilities for tests without alternate forms ranged from 0.41 to 0.77, but reliabilities were lower for tests with alternate forms (0.11 to 0.83). Paired t-tests revealed few significant differences in group performance between test administrations. Performance of urban Thai participants was compared to 29 rural Thai participants of similar age and sex. Parental education was significantly greater for urban vs. rural participants, resulting in significant differences in performance on tests of motor speed. CONCLUSIONS: This study supports the use of BARS for epidemiologic studies of neurotoxicants in Thailand, but highlights the sensitivity of these tests to differences in parental education and the need for improved alternate test forms.