Is paraquat highly toxic? Does banning paraquat harm the interests of farmers and affect agricultural production?

The ban on paraquat, a herbicide, has been discussed in Taiwan for many years, which is a continuation of the policy of successive governments gradually exiting highly toxic pesticides and switching to alternative pesticides. Referring to the empirical research results at home and abroad, the best way to prevent casualties caused by highly toxic paraquat should be to ban and use alternative drugs.

This paper discusses the possible ways and reasons for preventing paraquat injury, quotes the relevant evidence, considers the overall interests, and collates it in the way of question and answer, hoping to promote rational policy discussion.

1. Is paraquat highly toxic? All the problems are suicides?

Paraquat is particularly toxic to the human body, and a small amount of paraquat may cause severe systemic reactions after a few days, including pulmonary fibrosis, respiratory failure, and painful death. Because there is no antidote, the mortality rate is high. The late Dr. Lin Jie Liang reported that the mortality rate of paraquat poisoning treated by traditional methods was as high as 92%. He tried to improve the treatment, but the mortality rate was still as high as 66% [1].

In contrast, according to a report by the Rong General team in Taipei, the fatality rates of Jiapusai and Gufen, both widely effective herbicides, are only 7% [2] and 6% [3], respectively, which is much lower than 66-92% of paraquat, which also means that many unfortunate deaths can be avoided if paraquat is replaced by other pesticides.

In Taiwan in the past six years (2013-2018), 1253 people died of paraquat poisoning, equivalent to an average of 200 a year, and one person dies every two days. Among them, suicide accounted for the majority (90%), but 67 people (accounting for 5% of all paraquat deaths) were found to be accidental poisoning by prosecutors in the past six years. Therefore, the deaths caused by paraquat are not only suicides, but also accidental deaths. Banning paraquat can not only reduce suicide, but also reduce unfortunate accidental deaths and protect the overall safety of the community.

Second, paraquat is all right to touch the skin. Is long-term exposure safe?

Paraquat may enter the body in a variety of ways, including the skin. In the case of intact skin, paraquat is absorbed in only a small amount. However, paraquat may first cause skin burns and damage, and then be absorbed into the human body from the damaged place, resulting in systemic poisoning, there have been deaths abroad [4]. In Taiwan, Dr. Lin Jie Liang's team reported a case of skin burning and paraquat systemic poisoning [5]. Therefore, if there is a large amount of skin contact, or if the skin has multiple wounds, it is necessary to rinse and seek medical attention as soon as possible.

In addition to acute injury, long-term exposure to paraquat can also cause nerve damage and Parkinson's disease. Paraquat was banned in all EU countries in 2007 on the grounds that paraquat could not be ruled out as a cause of Parkinson's disease. A study at National Taiwan University Hospital found that people who used paraquat for more than 20 years had a six-fold increased risk of Parkinson's disease compared with people who did not use paraquat. International studies have shown that long-term users have a threefold increase in the risk of Parkinson's disease [7].

Third, banning paraquat to harm the interests of farmers? Affect agricultural production?

Banning paraquat and using alternative pesticides involves changing old habits and using new drugs, which may indeed cause inconvenience to users, and it is necessary for relevant departments to actively provide information and guidance on the use of alternative pesticides. However, if the gains and losses of the use of paraquat are fully considered, especially the loss of life, the cost of using paraquat in rural areas is very high.

Some people argue that paraquat is cheap. In terms of herbicidal use, the average ex-factory price of paraquat per liter from 2005 to 2014 is 98 yuan, Jiaposai is 109yuan, and paraquat is 248yuan [8]. Compared with carapaxel, paraquat does not necessarily have an absolute price advantage, and the price of herbicide has also declined significantly in recent years. Paraquat has not been the largest-selling herbicide in the Taiwan market since many years ago. In the actual application, the dilution ratio and application times should also be taken into account. Because paraquat is a contact herbicide, "weeding without root removal" may need to be used more times, which may not have an advantage in cost.

More importantly, if the deaths caused by paraquat are taken into account, the overall social losses caused by paraquat far outweigh the benefits in terms of price. We have estimated that the annual deaths caused by paraquat (more than 160 people) and the loss of income of more than 1.3 billion yuan [9] are borne entirely by family members and society as a whole, and this does not include the intangible loss of grief among relatives and friends. At the same time, these losses mainly occurred in agricultural areas, which would benefit most if paraquat was banned.

Will banning highly toxic pesticides affect agricultural production? Research shows that sales of agricultural products have not declined in Sri Lanka [10], South Korea [11] and Bangladesh [12] after banning pesticides, including paraquat.

4. Can banning paraquat reduce deaths? Is suicide transferred to other methods?

Although a few of the deaths caused by paraquat were accidental, the vast majority committed suicide. Countries in the world where paraquat is banned do observe a decline in pesticide suicide mortality, as well as overall suicide mortality.

Previous studies we have collaborated with Korean and Sri Lankan scholars have shown that after paraquat was banned in these two countries, the pesticide suicide mortality rate decreased by 40-50%, the number of deaths decreased by 850-950 a year, and the suicide mortality rate of other methods did not increase. As a result, the overall suicide mortality rate decreased by 13-21%.

As can be seen from figure I, Sri Lanka gradually banned three highly toxic pesticides, including paraquat, between 2008 and 2011, and the pesticide suicide mortality rate decreased by 50 per cent between 2011 and 2015. More importantly, the overall suicide mortality rate also decreased by 21%, while the suicide mortality rate of other suicide methods increased only slightly by 2%, and there was no obvious "transfer" to other methods. In 2015 alone, 937 suicides were reduced [13].

Suicide rate decreases after banning three highly toxic pesticides (including paraquat) in Sri Lanka

Banning highly toxic pesticides can reduce suicide, mainly because it reduces the fatality rate of poisoning and gives many impulsive suicides a second chance to turn the crisis into a turning point [14]. Studies show that 24-74% of suicides take less than 10 minutes from thought to action [15]. Drinking paraquat during interpersonal quarrels, depression, acute stress, or even temporary drunkenness will lead to irreversible consequences, while banning paraquat will have a chance to avoid danger.

Studies in Taiwan [16] and abroad [17] found that only 2% of people sent to hospital for suicidal behavior committed suicide again a year later, and the other 98% did not die of suicide, which means that if the first suicide attempt can be saved, the vast majority of people will not commit suicide again.

The phenomenon of "impulse" shows that removing the most toxic pesticides can save lives, and most planners will not try again or turn to other methods. Many people think that "people who want to commit suicide will always want to commit suicide", but the World Health Organization claims that this is a misunderstanding that makes us miss the opportunity to save lives [18].

Limiting lethal tools to reduce suicide is an effective and evidence-supported strategy recognized by the World Health Organization [18]. There are several conditions to achieve the effect, including that the restricted tools are common, lethal, easy to obtain, can be restricted, and are not easy to be transferred to other methods. In Taiwan, banning highly toxic pesticides is most suitable for these conditions. Other tools such as hanging are more difficult to restrict [14]. Restricting tools cannot avoid all suicides, but it is an important part of multiple suicide prevention and control strategies and is targeted. Some people mistakenly think that all potential tools should be restricted, but in fact this is not the case.

In fact, not only do people commit suicide, but improving the safety of tools and the environment is also used to prevent accidents such as car accidents. over the years, the medical community has gradually replaced drugs with low safety, such as barbiturate with high fatality rate, with sleeping drugs with high safety. Banning the most toxic pesticides and replacing them with safer drugs is based on the same principle and is not difficult to understand.

5. what is the ban on paraquat in other countries? What is China's policy of banning paraquat?

There are more and more countries in the world that ban paraquat. According to statistics seven years ago (2012), paraquat was banned in 36 countries [19], but the latest statistics from the Council of Agriculture show that there are now 64 banned countries, and neighboring Asian countries similar to Taiwan have gradually banned paraquat in recent years, including South Korea (banned in 2012), Vietnam (banned in 2017), Malaysia (banned in 2020) and China (banned in 2016). Soluble gels are banned in September 2020).

In China, for example, the Ministry of Agriculture and Village announced on October 17, 2018, "to further strengthen the supervision and management of paraquat in order to protect the lives of the people", adopting four measures [20].

Strict enforcement of paraquat regulations: the sale and use of paraquat is prohibited, but production and export are not prohibited.

"Comprehensive monitoring of paraquat production trends": monitor production exports and inventory, and strictly prevent exports from turning to domestic sales

"thoroughly check and deal with the problems left over by paraquat": paraquat for comprehensive inventory and recovery, and the disposal cost shall be borne by the production enterprise, business unit or local government.

"severely crack down on illegal production and operation of paraquat": strictly investigate the addition of paraquat to other pesticides, or the use of paraquat instead of counterfeit.

China's complete policy of banning paraquat is worthy of our reference, especially after the ban, recycling is carried out to speed up the effect of reducing deaths. At the same time, if Taiwan continues to use paraquat and imports raw materials from China, it will become an absurd situation banned by China but exporting paraquat to Taiwan will continue to lead to tragedy.

It was mentioned that paraquat was not banned in some major countries such as the United States and Japan. However, agriculture in the United States is dominated by large farmers, which is different from small farmers in Taiwan, who buy, store and use pesticides on their own. In the United States, paraquat is classified as "restricted" and can only be used by licensed operators. However, some scholars have pointed out that the policy of banning harmful pesticides (including paraquat) in the United States lags far behind other major countries that use pesticides, including the European Union (banning paraquat in 2007), China (banning paraquat in 2016), and Brazil (to ban paraquat in 2020) [21]. The American experience should not apply to Taiwan.

In Japan, in view of the harm of paraquat, paraquat was changed from 24% solvent to 5% solvent as early as 1986 (24% solvent is still used in Taiwan), the sales channel is also controlled, and local production of paraquat in Japan was banned in 1999 [22]. The overall use has dropped to a very low level, and the number of deaths has also decreased [23]. However, the fatality rate of paraquat is still as high as 80%, indicating that paraquat is highly toxic even if the concentration is reduced [23].

6. Apart from banning, are other management methods effective?

Other methods to limit highly toxic pesticides, studies have shown that most of them have no effect, only the effect of prohibition is the most clear [24]. Here are six ways to manage paraquat and their possible effects:

Add emetic, warning color, and adsorbent to reduce absorption: Taiwan has required paraquat to add emetic and warning color since 1997, but the death toll of paraquat has increased from 118 that year to 200 in recent years, indicating ineffectiveness. Because paraquat is so toxic that a small amount of absorption can be fatal. Studies on the addition of emetic, laxative, and algin adsorbents have also been carried out abroad, and the fatality rate has decreased slightly from 73% to 63%, with limited results, which is still much higher than other pesticides [25].

Concentration reduction: as mentioned above, Japan is one of the few countries that limit the conversion of paraquat from 24% to 5%. However, the fatality rate of paraquat poisoning is still as high as 80% [23]. It can still cause many poisoning deaths.

Change the dosage form: for example, change paraquat into lozenges to reduce self-poisoning. However, the solvent still needs to be soaked before use and may be stored at home, which cannot change the situation in which the solvent is readily available.

Restrictions on use: Ireland has implemented a restricted sales system (which requires a license or related industry to buy paraquat), safety education, pesticide safety labels, etc. [26], while South Korea has tried a buyer registration system [11]. As a result, none of these measures reduced the number of paraquat suicides, and in the end, paraquat was banned in both countries. The Taiwan suicide Prevention and Control Center once collected data on paraquat poisoning and found that 60% of paraquat was stored at home instead of buying it on the spot, so it was limited to restrict sales.

Distribute pesticide storage boxes: encourage farmers to store pesticides in locked boxes to reduce poisoning by themselves or their families on impulse. According to a study of up to 220000 people, it was found that this method did not produce the desired effect at all. Comparing areas with and without boxes, the incidence of pesticide poisoning was almost the same [27]. It may be difficult to rely on farmers for continuous safe storage of pesticides. After three years of the study, only half of the farmers used safety boxes and locked them.

Professional spray system: the restriction that only pesticide spraying agents can buy and store paraquat, if thoroughly implemented, and the gradual depletion of paraquat previously stored in farmers, may have a similar effect as the ban. However, at present, there is no perfect and strict spray system in Taiwan, and ordinary farmers may not be willing to buy this service. At the same time, paraquat may still be spread to ordinary farmers through spray agents, so that the effect of control will be discounted.

For the smooth implementation of the prohibition policy, a complete package and alternative drug program is needed. The Council of Agriculture has proposed a number of alternative agents for the use of weeding, but in terms of the use of fallen leaves, as the alternative agents have only been introduced in recent years, it is urgent for the relevant units to continue to optimize the results, provide farmers with clear guidelines and incentives for use, and make efforts to promote them.

In the author's interview, the farmer pointed out that the key point is to have alternatives or drugs, and do not insist on the use of specific drugs, after all, we also attach importance to the safety of drug use. It is expected that people from all walks of life will refer to the evidence and focus on assisting farmers to switch to alternative drugs, or use other weed management or defoliation schemes, so that highly toxic pesticides can exit, is to create a win-win situation!