Associations of maternal organophosphate pesticide exposure and PON1 activity with birth outcomes in SAWASDEE birth cohort, Thailand.

Prenatal organophosphate (OP) pesticide exposure has been reported to be associated with adverse birth outcomes and neurodevelopment. However, the mechanisms of toxicity of OP pesticides on human fetal development have not yet been elucidated. Our pilot study birth cohort, the Study of Asian Women and Offspring's Development and Environmental Exposures (SAWASDEE cohort) aimed to evaluate environmental chemical exposures and their relation to birth outcomes and infant neurodevelopment in 52 pregnant farmworkers in Fang district, Chiang Mai province, Thailand. A large array of data was collected multiple times during pregnancy including approximately monthly urine samples for evaluation of pesticide exposure, three blood samples for pesticide-related enzyme measurements and questionnaire data. This study investigated the changes in maternal acetylcholinesterase (AChE) and paraoxonase 1 (PON1) activities and their relation to urinary diakylphosphates (DAPs), class-related metabolites of OP pesticides, during pregnancy. Maternal AChE, butyrylcholinesterase (BChE) and PON1 activities were measured three times during pregnancy and urinary DAP concentrations were measured, on average, 8 times from enrollment during pregnancy until delivery. Among the individuals in the group with low maternal PON1 activity (n=23), newborn head circumference was negatively correlated with log10 maternal ∑DEAP and ∑DAP at enrollment (gestational age=12±3 weeks; ß=-1.0 cm, p=0.03 and ß=-1.8 cm, p<0.01, respectively) and at 32 weeks pregnancy (ß=-1.1cm, p=0.04 and ß=-2.6 cm, p=0.01, respectively). Furthermore, among these mothers, newborn birthweight was also negatively associated with log10 maternal ∑DEAP and ∑DAP at enrollment (ß=-219.7 g, p=0.05 and ß=-371.3g, p=0.02, respectively). Associations between maternal DAP levels and newborn outcomes were not observed in the group of participants with high maternal PON1 activity. Our results support previous findings from US birth cohort studies. This is the first study to report the associations between prenatal OP pesticide exposure and birth outcomes in Thailand.

Blood cholinesterase activity levels of farmers in winter and hot season of Mae Taeng District, Chiang Mai Province, Thailand.

Organophosphate and carbamate pesticides have been widely used by farmers for crop protection and pest control. Inhibition of acetylcholinesterase (AChE) in erythrocyte and butyrylcholinesterase (BChE) in plasma is the predominant toxic effect of organophosphate and carbamate pesticides. Mae Taeng District, Chiang Mai Province, is one of the large areas of growing vegetables and fruits. Due to their regular exposure to these pesticides, the farmers are affected by this toxicity. The objective of the study was to examine the AChE and the BChE activity levels in the blood of 102 farmers for comparison of exposure in two cropping seasons, winter and hot. Blood samples were collected in December 2013 (winter) and April-June 2014 (hot). A total of 102 farmers joined the study, represented by 76 males (74.5 %) and 26 females (25.5 %). The age of most of the farmers was 53.4 ± 8.7 years. Out of 102, 21 farmers used carbamate pesticides. The results showed that the AChE and the BChE activity levels of all the farmers were 3.27 ± 0.84 Unit/mL and 2.15 ± 0.58 Unit/mL, respectively. The AChE and the BChE activity levels in males were 3.31 ± 0.88 Unit/mL and 1.97 ± 0.60 U/mL, respectively, during winter and 3.27 ± 0.82 Unit/mL and 2.15 ± 0.58 U/mL, respectively, during the hot season, and AChE and the BChE activity levels in females were 3.27 ± 0.82 U/mL and 2.44 ± 0.56 U/mL, respectively, during the hot season. The cholinesterase activity levels, both AChE and BChE, in the male farmers' blood had significant difference between the two seasons, while in the case of the female farmers, there was significant difference in the BChE activity levels, at p < 0.05. The BChE activity level was found to significantly correlate with self-spray (p < 0.05), which implies that the BChE activity decreased when they sprayed by themselves. The cholinesterase activity levels of the present study were lower than those of the other studies, which may be an indication of some chronic effect of exposure to anticholinesterase pesticides. Thus, it is recommended that the use of pesticides be decreased, together with increase in the awareness of the impact of pesticides on health; also recommended is regular monitoring of blood cholinesterase.

Pilot study of pesticide knowledge, attitudes, and practices among pregnant women in northern Thailand.

An estimated 200,000 children born in Thailand each year are at risk of prenatal exposure to pesticides and associated neurodevelopmental outcomes because of their mothers' agricultural occupations. Children born to non-agricultural workers may also be at risk of exposure from other pathways of maternal pesticide exposure, including exposure through home use, diet, and other environmental media. Pesticide exposure in Thailand has been linked to unsafe practices and beliefs about pesticides. However, limited information exists on pesticide knowledge, attitudes, and practices among pregnant women in Thailand or elsewhere. Obtaining this information is essential to understand the factors associated with prenatal pesticide exposure, identify populations potentially at risk, and ultimately protect pregnant women and their children. We administered surveys to 76 pregnant women in northern Thailand and used multivariable logistic regression to evaluate associations among pesticide-related knowledge, pregnancy trimester, and pesticide use behavior. In this pilot study, lower knowledge score and earliest trimester of pregnancy were marginally (p < 0.1) associated with unsafe practices in the home, but not at work. Women who worked in agriculture or applied pesticides before becoming pregnant, or who had a previous child were significantly (p < 0.05) more likely to engage in unsafe behaviors in the home during their current pregnancy. We preliminarily conclude that increasing pesticide-related knowledge among pregnant women may help promote safe practices and reduce prenatal exposure. Knowledge-based interventions may be most effective when implemented early in pregnancy and targeted to agricultural workers and other sub-populations at risk of pesticide exposure.