The early impact of paraquat ban on suicide in Taiwan

Abstract

Introduction

Pesticide ingestion is a leading method for suicide worldwide. Paraquat is a highly lethal herbicide when ingested. We assessed the impact of the first-stage ban on the import and production of paraquat (from February 2018) on suicides by pesticide poisoning in Taiwan.

Methods

Suicide data by method (pesticide vs. non-pesticide), pesticide (paraquat vs. non-paraquat), and area/sex/age were extracted from the national cause-of-death data files (2011–2019). Negative binomial regression was used to estimate changes in suicide rates in 2019, compared to the expected rates based on pre-ban linear trends (2011–2017).

Results

The paraquat ban was followed by an estimated 37% (rate ratio [RR] = 0.63, 95% confidence interval [CI] 0.54–0.74) reduction in pesticide suicide rate (190 [95% CI 116–277] fewer suicides) in 2019, mainly due to a 58% (RR = 0.42, 95% CI 0.33–0.54) reduction in paraquat suicides (145 [95% CI 92–213] fewer suicides). Larger absolute reductions in pesticide suicides were found in rural areas, males, and the elderly (aged 65+ years) than their counterparts. Except for a 10% (95% CI 3–18%) reduction in overall suicide rates in the elderly, there was no statistical evidence for a change in non-pesticide and overall (all-method) suicides.

Conclusion

The ban on the import and production of paraquat was followed by a fall in whole-population pesticide and paraquat suicides and elderly suicides in Taiwan.

Keywords:

• Pesticide ban
• pesticide suicide
• suicide prevention
• paraquat

Acknowledgements

We thank the National Taiwan Suicide Prevention Center and Department of Mental and Oral Health, Ministry of Health and Welfare, Taiwan, for their support on data compilation.

Disclosure statement

SSC, DG and ME are affiliated with the Centre for Pesticide Suicide Prevention, which is funded by an Incubator Grant from the Open Philanthropy Project Fund, an advised fund of Silicon Valley Community Foundation, on the recommendation of GiveWell, USA. DG is supported by the National Institute for Health Research Biomedical Research Centre at University Hospitals Bristol and Weston National Health Service Foundation Trust and the University of Bristol. The views expressed in this publication are those of the authors and not necessarily those of the National Health Service, the National Institute for Health Research, or the Department of Health and Social Care. DG also reports grants from WHO, during the conduct of the study, and being a member of the scientific advisory group for a Syngenta-funded study to assess the toxicity of a new paraquat formulation and the scientific advisory group for a pesticide self-storage project funded by Syngenta (between 2003 and 2011), chairing a data monitoring and ethics committee for a Syngenta-funded trial of the medical management of paraquat poisoning, receiving travel costs to attend research Syngenta-funded trial meetings, and being an expert adviser to the first WHO consultation on best practices on community action for safer access to pesticides (2006), all outside the submitted work. ME is a WHO member of the FAO–WHO Joint Meeting on Pesticide Management, and reports receiving an unrestricted research grant from Cheminova (2012) and travel expenses from Syngenta to attend meetings (2005–06). DG and ME declare relevant grants from the Wellcome Trust and American Foundation for Suicide Prevention, were expert advisers to the WHO consultation on cost-effectiveness of suicide prevention interventions, including pesticide regulation (2019), provided technical assistance for the development and publication of “Suicide Prevention: A Resource Guide for Pesticide Registrars and Regulators” (2019). SSC is a reviewer of “Suicide Prevention: A Resource Guide for Pesticide Registrars and Regulators” (2019). No potential conflict of interest was reported by the author(s).

Additional information

Funding

This project was supported by [Grant SRG-0-028-1] awarded to Shu-Sen Chang from the American Foundation for Suicide Prevention, a grant awarded to Shu-Sen Chang from Centre for Pesticide Suicide Prevention, University of Edinburgh [CT-5699(a)], and a grant awarded to Ming-Been Lee from Taiwan Ministry of Health and Welfare [M08B8116]. The content is solely the responsibility of the authors and does not necessarily represent the official views of the American Foundation for Suicide Prevention or Taiwan Ministry of Health and Welfare.