Estimation of glyphosate biological half-life among farmers and residents in Thailand

Abstract

Glyphosate is a widely used herbicide worldwide. Research on human health effects has been limited and the toxicokinetics of glyphosate have not been widely examined. This research aimed to study the excretion profile and half-life of glyphosate in farmers and residents who use glyphosate to control weeds in their agricultural fields and near their households, respectively. Multiple spot urine samples per day were collected from the participants for 3 consecutive days after spraying glyphosate. The participants were interviewed about general characteristics, planting activities, glyphosate use, and their health problems related to glyphosate use. Glyphosate concentrations in urine samples were determined by HPLC with a fluorescence detector. The average age of residents (56.4 years) was significantly higher than that of farmers (45.5 years). The glyphosate excretion profile of most participants showed a gradual decline in glyphosate concentrations, but with or without additional exposures some of the profiles showed a jagged pattern of decline. The average urinary half-life of glyphosate in all participants was 24.58 h (95% CI: 18.43–30.73) and 20.95 h (95%CI: 16.85–25.05) for creatinine adjusted and non-adjusted measurements, respectively. The urinary glyphosate half-life measurements among the residents and farmers were not significantly different.

Keywords:

• good health and well-being
• life on land
• urinary glyphosate
• half-life
• farmer and resident

Acknowledgements

The authors are most grateful to the participants and research assistants for participating and assisting in this study.

Authors’ contributions

Anusorn Paosungnoen: Responsible for sample collection, data analysis, result interpretation, and writing original draft of the manuscript. Pornpimol Kongtip: Provided supervision in the presented work, involved in the writing, editing of the manuscript and funding acquisition. Noppanun Nangkongnab: Provided supervision and guidance. Sukhontha Siri: Provided guidance on statistical analysis. Mark G. Robson: Provided guidance and editing of the manuscript. Susan R. Woskie: Proofread all manuscript drafts, language editing, and funding acquisition.

Disclosure statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyzes, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Additional information

Funding

This research was financially supported by the Nakhon Ratchasima Rajabhat University under grant number 7/2561; and NIH, the Fogarty International Center, the National Institute of Environmental Health Science, and the Center for Disease Control, under the award numbers U01 TW010091 and U2R TW010088.