Biochemical and cellular responses of the freshwater mussel, Hyriopsis bialata, to the herbicide atrazine.

The present study aimed to evaluate biochemical and cellular responses of the freshwater mussel, Hyriopsis bialata, to the herbicide atrazine (ATZ). The mussels were exposed to environmentally-relevant concentrations of ATZ (0, 0.02 and 0.2 mg/L) and a high concentration (2 mg/L) for 0, 7, 14, 21 and 28 days. Tissues comprising male and female gonads, digestive glands and gills were collected and assessed for ethoxyresorufin-O-deethylase (EROD) activity, glutathione S-transferase (GST) activity, multixenobiotic resistance mechanism (MXR), histopathological responses, DNA fragmentation and bioaccumulation of ATZ and its transformation derivatives, desethylatrazine (DEA) and desisopropylatrazine (DIA). Additionally, circulating estradiol levels were determined. It appeared that ATZ did not cause significant changes in activities of EROD, GST and MXR. There were no apparent ATZ-mediated histopathological effects in the tissues, with the exception of the male gonads exhibiting aberrant aggregation of germ cells in the ATZ-treated mussels. Contrarily, ATZ caused significant DNA fragmentation in all tissues of the treated animals in dose- and time-dependent manners. In general, the circulating estradiol levels were higher in the females than in the males. However, ATZ-treated animals did not show significant alterations in the hormonal levels, as compared with those of the untreated animals. Herein, we showed for the first time differentially spatiotemporal distribution patterns of bioaccumulation of ATZ, DEA and DIA, with ATZ and DEA detectable in the gonads of both sexes, DEA and DIA in the digestive glands and only DEA in the gills. The differential distribution patterns of bioaccumulation of ATZ and its derivatives among the tissues point to different pathways and tissue capacity in transforming ATZ into its transformation products. Taken together, the freshwater mussel H. bialata was resistant to ATZ likely due to their effective detoxification. However, using DNA damage as a potential biomarker, H. bialata is a promising candidate for biomonitoring aquatic toxicity.

Pesticide residues on children's hands, home indoor surfaces, and drinking water among conventional and organic farmers in Thailand.

This study measured pesticide levels on children's hands, home indoor surfaces, and drinking water among Thai conventional and organic farm families in three provinces. Farm families in Nakhonsawan and Phitsanulok provinces were the conventional farmers and those in Yasothon province were the organic farmers. Samples were collected in the dry and wet seasons over 2 years (2017 and 2018). All samples were analyzed for organophosphates (OPs), carbamate, pyrethroid, triazines, glyphosate, and aminomethylphosphonic acid (AMPA). On children's hands, the highest concentrations for the 2 palmar surfaces were found for cypermethrin (7.46 µg) and fipronil (2.88 µg). On home surfaces of approximately 1000 cm2, the highest concentrations were found for cypermethrin (27.94 µg) and fipronil 49.76 µg)/1000 cm2. For the conventional farmers, the most common pesticides on children's hand wipes were cypermethrin and fipronil, which are used as in-home pesticides as well as agricultural pesticides. However, home surface wipes showed other pesticides associated with agriculture were presented in the home during the seasons when they were used, suggesting spray drift or carry home sources for these pesticides. During the wet season, pesticides were found in the drinking water of all provinces. Most common were fenitrothion, profenofos, fenthion, atrazine, and AMPA. Profenofos was found at levels above the health guidelines. During 2017, there was extensive flooding in Thailand which may have contributed to the drinking water contamination, even though most farmers report using tap water or bottled drinking water. Future work is needed to assess the risk of all sources of pesticide exposures in children and to repeat the drinking water pesticide contamination analysis.

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.