Inhalation exposure of organophosphate pesticides by vegetable growers in the Bang-Rieng subdistrict in Thailand.

This study investigated inhalation exposure to organophosphate pesticides (OPPs) and evaluated the associated health risks to vegetable growers living in the Bang-Rieng agricultural community. Air samples were collected by using personal sampling pumps with sorbent tubes placed in the vegetable growers' breathing zone. Samples were collected during both wet and dry seasons. Residues of organophosphate pesticides, that is, chlorpyrifos, dicrotofos, and profenofos, were analyzed from 33 vegetable growers and 17 reference subjects. Results showed that median concentrations of OPPs in air in farm areas were in the range of 0.022-0.056 mg/m(3) and air in nonfarm areas in the range of <0.0016-<0.005 mg/m(3). The concentration of the three pesticides in the vegetable growers was significantly higher than that of the references during both seasons. The results also indicate that the vegetable growers may be at risk for acute adverse effects via the inhalation of chlorpyrifos and dicrotofos during pesticide application, mixing, loading, and spraying. It is suggested that authorities and the community should implement appropriate strategies concerning risk reduction and risk management.

Analytical method developed for measurement of dialkylphosphate metabolites in urine collected from children non-occupationally exposed to organophosphate pesticides in an agricultural community in Thailand.

There has been increasing concern in regards to organophosphate (OP) pesticide exposure among farm workers and their families in Thailand's agricultural areas. Therefore, the development of an analytical method for estimating OP pesticide exposure is necessary to allow for monitoring of OP pesticide exposures within these populations. This paper describes an analytical method developed to measure dialkylphosphate (DAP) metabolites in urine. The methods in this study are important in the biological monitoring of OP metabolites in agricultural families in Thailand and can be used as an initial guidance procedure in any environmental toxicological laboratory in Thailand.

Method of calculating tsunami travel times in the Andaman Sea region.

A new model to calculate tsunami travel times in the Andaman Sea region has been developed. The model specifically provides more accurate travel time estimates for tsunamis propagating to Patong Beach on the west coast of Phuket, Thailand. More generally, the model provides better understanding of the influence of the accuracy and resolution of bathymetry data on the accuracy of travel time calculations. The dynamic model is based on solitary wave theory, and a lookup function is used to perform bilinear interpolation of bathymetry along the ray trajectory. The model was calibrated and verified using data from an echosounder record, tsunami photographs, satellite altimetry records, and eyewitness accounts of the tsunami on 26 December 2004. Time differences for 12 representative targets in the Andaman Sea and the Indian Ocean regions were calculated. The model demonstrated satisfactory time differences (<2 min/h), despite the use of low resolution bathymetry (ETOPO2v2). To improve accuracy, the dynamics of wave elevation and a velocity correction term must be considered, particularly for calculations in the nearshore region.

Biological monitoring of organophosphate pesticides in preschool children in an agricultural community in Thailand.

Organophosphate pesticide exposures of preschool children in a Thailand agricultural community and reference children living outside the farm area in the same subdistrict were determined. Levels of dialkylphosphate (DAP) metabolites were measured in first-morning-void urine samples. During the dry season (April-May), the farm children excreted significantly higher levels of all DAP metabolites than the reference children did (Mann-Whitney U test, p < 0.05; Wilcoxon signed-rank text, p < 0.05). During the wet season (September-October), DAP metabolite levels were similar in the two groups. Reference children showed no significant difference related to season. Pesticide spraying during the dry season is a likely cause of the farm children's organophosphate exposures.

Organophosphate pesticide exposures of traditional and integrated pest management farmers from working air conditions: a case study in Thailand.

Concentrations of organophosphate pesticides, including chlorpyrifos and methyl parathion, were measured in ambient air breathed by farmers in Tambon Bang Rieng, Thailand. An exposure assessment and comparison was made between the levels of pesticide exposure of traditional and integrated pest management (IPM) farmers. Thirty-three air samples were collected during pesticide spraying. Traditional farmers were exposed to higher levels of the pesticide(s), with an average concentration of 0.19 mg/m3, compared with 0.037 mg/m3 for the IPM farmers. It was estimated that a farmer of Tambon Bang Rieng would be exposed to 81-12,261 mg of the organophosphate pesticide(s) via inhalation throughout his or her lifetime. Moreover, traditional farmers absorbed more of pesticide via inhalation than did IPM farmers.