More than 11 million Thai people (38%) work in agriculture, but since most are in the informal sector, government enforcement and support are very limited. As a result, working conditions on Thai farms vary greatly, putting the health of many agricultural workers at risk. A cross-sectional study in three Thai provinces collected information on the work activities and conditions of 424 farmers representing five farm types: rice, vegetable, flower, rice/vegetable, and flower/vegetable. The agricultural workers were mainly women (60%); their average age was 53 but ranged from 18 to 87 years. More than 64% worked more than 5 days/week. Seventy-four percent of them had only primary school education. A number of the health and hazardous working conditions surveyed were significantly different by farm type. Rice farmers were found to have the highest prevalence of allergies, nasal congestion, wheezing, and acute symptoms after pesticide use, while flower farmers had the lowest prevalence of these health outcomes. Rice farmers reported the highest prevalence of hazardous working conditions including high noise levels, working on slippery surfaces, sitting or standing on a vibrating machine, spills of chemicals/pesticides, and sharp injuries. The lowest prevalence of these working conditions (except noise) was reported by flower farmers. Vegetable farmers reported the highest prevalence knee problems, while rice farmers had the lowest prevalence. Among these farmers, more than 27 different types of pesticides were reported in use during the past year, with the majority reporting use once a month. The flower/vegetable farming group reported the highest frequency of good exposure prevention practices during pesticide use. They were the most likely to report using cotton or rubber gloves or a disposable paper masks during insecticide spraying. Those farmers who only grew vegetables had the lowest frequency of good exposure prevention practices, including use of personal protective equipment. The economic cost of work-related injuries and illnesses among informal sector agricultural workers in Thailand is unknown and in need of study. Gaps in the regulations covering pesticide sales allow farmers to purchase pesticides without adequate training in their safe use. Training targeted to farm type regarding safe pesticide use and the prevention of accidents and musculoskeletal disorders is needed. Studies of chronic health effects among Thai farmers are needed, with special emphasis on respiratory, metabolic disease and cancer.

Farmers in Thailand as well as their families are exposed to pesticides in the spraying season and dermal exposure is an important route. The main route of exposure for farmers' families seems to be through transfer from the farmer to family members or contamination of the home environment, rather than family members helping or playing on the farm. Showering or washing immediately after pesticide spraying greatly reduces the potential exposure of family members to pesticide residues.

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.