Estimation of involuntary excreta ingestion rates in farmers during agricultural practices in Vietnam

ABSTRACT

Soil-transmitted helminth (STH) infections caused 4.98 million years live with disability globally in 2014, mostly affecting the poor. When farmers handle excreta for reuse in agriculture, involuntary ingestion of excreta particles is an important infection pathway for STH infections. The aim of this study was to quantify farmers' ingestion of human excreta during common agricultural practices in Vietnam. The weight of excreta that remained on farmers' hands, the weight of excreta that would remain on a farmer' mouth after contact with hand, and the frequency of contact between hand to the mouth by observing farmers while they handled excreta were simulated and quantified. Our findings revealed that farmers are on average exposed 5.16 h to excreta handling per year. Based on this average exposure time, it was estimated that farmers ingest 91 mg of excreta per year (95% CI: 73–110 mg). Our study presents for the first time a robust quantitative estimation of excreta ingestion by farmers during excreta handling in agricultural practices. Hence, this paper makes an important contribution to more robust quantitative microbial risk assessment and health impact assessment related to STH infections and diarrhea in Vietnam and other similar settings where excreta is used as fertilizer.

KEYWORDS:

• human excreta
• exposure assessment
• occupational health
• farmer health
• vietnam

Acknowledgements

We are grateful for the kind cooperation and participation of the health station staff and community members in Hoang Tay commune. We thank Mr. Nguyen Duy Tien and Mrs Nguyen Bich Thao for supporting the data collection. We thank Mrs Julie Hood (a Canadian VWB/VSF volunteer) and Ms Kylie Cuthbertson (Australian volunteer) for an English language review of this manuscript and Dr Janna Schurer and Ms Lauren MacDonald for providing early comments on the manuscript. This work was supported by the Swiss National Science Foundation and the Swiss Agency for Development and Cooperation through the National Centre for Competences in Research (NCCR) North–South program. HNV was partly funded by the CGIAR research program on Agriculture for Nutrition and Health (A4NH).

Disclosure of potential conflicts of interest

No potential conflicts of interest were disclosed.

Ethics approval

This study was approved by the Ethics Review Board of the Hanoi School of Public Health (020/2012/YTCC-HĐ3) as well as by commune leaders in Hoang Tay.

Additional information

Funding

This study was conducted within the framework of the Swiss National Centre of Competence in Research (NCCR) North–South: Research Partnerships for Mitigating Syndromes of Global Change. The NCCR North-South is co-funded by the Swiss National Science Foundation (SNSF), the Swiss Agency for Development and Cooperation (SDC), and the participating institutions.