Taiwanese Journal of Psychiatry

: 2019  |  Volume : 33  |  Issue : 3  |  Page : 119--121

Banning paraquat would prevent nearly 200 deaths from suicide per year in Taiwan

Shu- Sen Chang1, David Gunnell2,  
1 Institute of Health Behaviors and Community Sciences; Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan
2 Population Health Sciences, Bristol Medical School; National Institute for Health Research Bristol Biomedical Research Centre, University Hospitals Bristol NHS Foundation Trust, University of Bristol, Bristol, England

Correspondence Address:
Shu- Sen Chang
No. 17, Xu-Zhou Road, Taipei 100, Taiwan

How to cite this article:
Chang SS, Gunnell D. Banning paraquat would prevent nearly 200 deaths from suicide per year in Taiwan.Taiwan J Psychiatry 2019;33:119-121

How to cite this URL:
Chang SS, Gunnell D. Banning paraquat would prevent nearly 200 deaths from suicide per year in Taiwan. Taiwan J Psychiatry [serial online] 2019 [cited 2021 Dec 8 ];33:119-121
Available from: http://www.e-tjp.org/text.asp?2019/33/3/119/268312

Full Text

In early 2007, a 45-year-old male patient was admitted to an emergency department in Taipei; he had swallowed a mouthful of paraquat after an argument with his wife. He anxiously asked the nurse whether he would die and said that he greatly regretted ingesting the pesticide. He died from respiratory failure three days later [1]. Tragedies like this are all too common in Taiwan. Self-poisoning is the most commonly used method in suicide attempts in Taiwan. In a study based on mortality data in 2006–2008, self-poisoning with paraquat caused at least 160 deaths a year, accounting for approximately half of all self-poisoning deaths using pesticides where the name of the product was recorded [2]. Recent estimates suggest that there are around 200 paraquat self-poisoning deaths per year (Ministry of Health and Welfare, personal communication). Ingestion of as little as a tablespoonful of paraquat can be fatal, and there is no effective antidote. The fatality of paraquat poisoning is around 66%–92% in Taiwan [3], much higher than that of almost all other pesticides [4].

We support a ban on paraquat and argue that it is an important, lifesaving policy that may prevent 200 deaths a year in Taiwan. There is strong evidence that restriction of access to commonly used and highly lethal methods of suicide leads to falls in method-specific and overall suicide rates [5],[6]. In this editorial, we summarize the evidence in support of the paraquat ban.

 Paraquat and the Arguments for Its Ban

Paraquat was licensed as a herbicide (i.e., weed killer) for farming in Taiwan in 1969. It was listed as a highly hazardous pesticide (HHP) in 1983 [7], and regulations required stenching agents and dyes to be added to the formulations to deter people from ingesting it from then. In 1997, it was required that emetics should also be added to the formulations of paraquat. The Agro-pesticides Management Act (2007) requires that HHPs are stored in a locked cabinet in shops, and the vendors should keep a record of the purchasers' personal information including name [8]. However, these measures do not appear to have prevented the many paraquat poisonings and deaths that occur every year.

In Taiwan, paraquat is widely used as a weed killer and is commonly stored in farming households. Indeed, licensed indications for its use were widened in 2011, permitting its use as a desiccant to assist harvesting adzuki bean. On several occasions, the Ministry of Health and Welfare has suggested a ban of paraquat because of its toxicity to humans. However, this has been contested, and those against the ban argue that paraquat is a cheap, effective, and environmentally friendly herbicide and there are no effective substitutes for its use as a desiccant. In October 2017, the Council of Agriculture, Taiwan's pesticide regulator, finally announced a plan to ban the two remaining pesticide products that contain paraquat. The ban will be in two phases – the ban on the import and production came to effect in February 2018, and the ban on the sale and use would become effective in February 2019. However, the second phase of ban was later postponed to February 2020; the reason cited by the Council for the delay is that unusually high amounts of paraquat-containing pesticides were sold in 2017–2018, and the Council estimated that one additional year was needed for the purchased paraquat products to be used up by farmers.

In June 2019, two potential presidential candidates from the opposition party criticized the paraquat ban saying that it will substantially increase farmers' costs and arguing for careful management rather than a ban of paraquat. The Council responded that the scheduled ban will remain unchanged as paraquat is highly toxic, and alternative, lower toxicity herbicides and chemicals are now available for the purposes of weed-killing and harvesting aid.

Most suicidal behaviors are impulsive. Research shows that 24%–74% of suicide attempters act within 30 min of the first thinking about suicide [9]. Their choice of poison determines whether they survive or die as a result of their suicide attempt. The late toxicologist Ja-Liang Linand his colleagues based at the Chang Gung Memorial Hospital reported that repeated pulse therapy of cyclophosphamide and steroids would reduce the fatality of paraquat poisoning from 92% to 66% [3], which is still far higher than the 7% [10] and 6% [11] fatality ratio of alternative herbicides glyphosate and glufosinate, respectively, based on reports from Taiwan National Poison Control Center. However, a more recent randomized controlled trial from Sri Lanka showed no evidence of the effectiveness of high-dose immunosuppression on improving the survival in paraquat-poisoned patients [12].

The majority of people who attempt suicide and survive do not make repeated attempts. In Taiwan, research suggests that only 6%–10% of attempters re-attempted suicide [13],[14],[15] and only 1%–2% died by suicide [16],[17] within one year. In contrast, in view of paraquat's high case fatality, most people who ingest it do not get a second chance, and eliminating paraquat would save many lives.

Our previous studies showed that Taiwan's earlier bans on pesticides do not appear to lead to a reduction in the rates of suicide by pesticide poisoning [18]. This is most likely to be because these bans do not include paraquat, which was the main pesticide involved in fatal self-poisonings [2]. Our previous studies also showed that pesticide ingestion is the third most common method for suicide in Taiwan and contributes to the higher overall suicide rates in rural areas than urban areas [19].

 The Burden of Paraquat Self-Poisoning

In 2013–2018, a total of 1,253 people died by paraquat self-poisoning in Taiwan – approximately 200 deaths/year or more than one death every two days. These deaths accounted for 41% of 2,716 suicides by pesticide poisoning and 5% of 22,283 overall suicides in the same period. Paraquat accounted for the highest proportion of total suicides in rural counties. In 2013-2018, the percentages of suicides due to paraquat self-poisoning were 17.6%, 15.3%, 12.2%, 12.1%, 12.0%, and 12.0% in Taitung, Hualien, Chiayi, Changhua, Yunlin, and Yilan counties, respectively. We anticipate that a ban on paraquat would be followed by the greatest reduction in suicide rates in these areas. Some may be concerned about the substitution by other methods or poisons. However, because of the high lethality of paraquat, if people used other methods or poisons, they would have a considerably lower risk of death; for example, the fatality of self-poisonings using drugs and other nonpesticide chemicals is less than 5% [20].

Hospital-based data also show the very high burden of mortality of self-poisonings using paraquat. In our ongoing pilot study based on hospital records collected from five hospitals in different parts of Taiwan, data from a sample of 504 patients who self-poisoned using pesticides showed that paraquat poisoning accounts for 33% of these self-poisonings and 78% of in-hospital deaths (Chang SS, et al., unpublished observations).

 Evidence for the Effectiveness of Paraquat Ban and Alternative Approaches

Previous studies strongly indicated that a ban of HHPs would decrease suicide rates from pesticide poisoning and in some circumstances, overall suicide rates. The impact of pesticide bans has been studied in six countries; in five countries the bans are followed by falls in pesticide suicides and in three these falls resulted in reductions in total suicides [21]. In South Korea, the rate of suicide by pesticide ingestion is dropped 37% compared to the expected rate in the year after paraquat was completely banned (2013); this impacted on overall suicide rates, which fell by 13% in 2011–2013 [22]. In Sri Lanka, the ban of paraquat and two organophosphates is followed by a 50% and 21% reduction of pesticide and overall suicide rates, respectively, in the five years after the ban [23].

Short of bans, a number of other approaches to reducing the death toll from pesticide poisoning has been suggested. These include sales restrictions, reduced concentration of product, new formulations, and lockable storage boxes. Evidence indicates that the impact of these approaches on suicide is limited.

Compared to bans, restricting the use and sale of HHPs appears to have less of an effect on reducing suicide [21]. In the 1960s and 1970s, to tackle the rising death rates from paraquat poisoning, Ireland implemented measures including restricting its sale to licensed dealers and agriculture-related occupations, reducing the number of retail outlets, educating farmers, and safety labeling; however, they were ineffective in reducing the number of paraquat suicides, and paraquat was later banned throughout European Union countries in 2007. From 1999, South Korea implemented measures such as setting standards for handling, compulsory education in pesticide use for farmers and sellers, and enforcement of labeling, but the number of suicides involving paraquat did not decrease significantly until the recent ban in 2011–2012 [24].

None of the restrictions implemented in other countries, except bans, would prevent household storage of paraquat; such storage remains common in agricultural areas of Taiwan. Even a small amount of paraquat ingested impulsively can be fatal and thus, these restrictive measures are unlikely to be effective. A survey by the Taiwan Suicide Prevention Center indicated that 60% of people who ingested paraquat use paraquat stored in households. It is only an outright ban that can completely remove paraquat and prevent related harms and deaths.

In Malaysia, a ban on the use of paraquat was implemented in 2005–2006 but was later lifted and changed to limited use, and thus farmers can continue to stock the herbicide in households. The number of people who died from paraquat poisoning was increased markedly from 34 in 2006 to 187 in 2015, according to data from the Malaysia National Poison Centre [25].

Japan used the approach of reducing the concentration of paraquat solution from 24% to 5% from 1986; however, case fatality following paraquat poisoning remained high (80%) [26].

Manufacturers of paraquat have used other approaches in an attempt to make their product safer. In Sri Lanka, the introduction of a new formulation of paraquat containing an increased concentration of emetics, a purgative, and an alginate that slows the absorption of paraquat had only a modest impact on case fatality – it fell from 73% to 63% [27], which is still much higher than that of alternative herbicides.

The effectiveness of safe storage of pesticides using locked boxes has been recently investigated in a large randomized trial in Sri Lanka [28]. No difference in the rates of self-poisoning using pesticides has been found in the intervention versus control villages. Critically, only half of the households continued to use and lock the box after three years, indicating that this is not a sustainable approach.

More than 60 countries have already banned paraquat. China banned the sale and use of paraquat solution in 2016 and will further ban water-soluble paraquat gel in 2020. However, China has not banned the production of paraquat for export. It will be very unfortunate if paraquat exported from China continues to contribute to self-poisoning deaths in Taiwan.


The causes of suicide are complex, involving biological, psychological, social, cultural, and environmental factors. Therefore, its prevention requires multifaceted actions. As psychiatrists, we are well-trained to provide support and treatments for people with suicide risk. A ban on paraquat can enhance the chance of survival in patients who have ingested the pesticide, allowing us the opportunity to provide the professional help needed, for example, treating psychiatric disorders which are common among people who self-poisoned using pesticides [29]. We together could advocate and support the policy to ban paraquat, and other HHPs with alternative pesticides available, to prevent suicides and save many lives.


The pilot hospital-based study of suicide by pesticide poisoning in Taiwan was funded by Centre for Pesticide Suicide Prevention (CPSP), University of Edinburgh, UK (principal investigator, SSC, the first author).

DG, the second author, is supported by the National Institute for Health Research Biomedical Research Centre at University Hospitals Bristol NHS Foundation Trust and the University of Bristol.


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