New research offers fresh insights into national, regional, and international efforts to regulate one of the world’s most controversial, yet widely used, pesticides.
The study, conducted by the Centre for Pesticide Suicide Prevention, reviewed the effects of various restrictions and regulations on instances of poisoning and death caused by this highly toxic pesticide. Findings showed that countries implementing full bans experienced the most significant reductions in pesticide-related deaths.
A controversial pesticide
Paraquat is one of the most commonly used herbicides worldwide – used by farmers to control unwanted plants and prepare fields for planting. However, it is also highly poisonous and fatal to humans when ingested. There is currently no antidote or effective treatment available for paraquat poisoning.
Due to high rates of poisoning and deaths, numerous countries have decided to restrict its use or ban it completely. At least 74 countries have now removed it from domestic use.
Despite this, paraquat remains in use in many low and middle-income countries, where its availability is continuing to pose serious public health risks. In many cases, insufficient data on exposure and poisoning prevents bans from being implemented.
Three regulatory approaches: assessing their effectiveness
The study explored three regulatory approaches – formulation changes, restrictions, and phase-outs and bans – analysing which countries had adopted these measures and their resulting impact on public health.
Formulation changes
Formulation changes involve modifying the product itself in an attempt to make it ‘safer’. These adjustments have included the introduction of a coloured dye and odour (to deter ingestion), an emetic agent to induce vomiting, a gelling agent, and product dilution.
Countries such as Sri Lanka, Japan, and Taiwan have adopted these regulations. However, their effectiveness has been limited.
In Taiwan, the addition of odours, dyes, and emetics failed to significantly reduce the number of fatal poisonings. The country later implemented a ban on paraquat in 2020. Both Sri Lanka and Japan have chosen to reduce the concentration of paraquat products. However, these have only been modestly effective at reducing deaths, and the case fatality rate has remained high compared to that of other pesticide poisoning cases.
Restrictions on sale, purchase and use
In countries where paraquat is restricted, its use is still permitted, however its access and availability are controlled and limited. This may include restrictions around who can buy and use paraquat, and what it can be used for.
In New Zealand, for example, paraquat can only be handled by certified users, with additional regulations governing buffer zones and spray droplet size. In Australia, special authorisation is required for its purchase, possession, and use, and it is banned for domestic use. In Colombia, paraquat is restricted to certain crops, and aerial application is prohibited.
While these restrictions have shown some success, they tend to be more effective in high-income countries where there is greater capacity to enforce regulations.
In contrast, the implementation of these restrictions has been less effective in low and middle-income countries that have high numbers of paraquat poisoning and deaths. For instance, although paraquat is approved for use on only nine crops in India, it is often used illegally on up to 25 crops.
Both South Korea and Taiwan have restricted paraquat use in the past, however there is no evidence that these measures significantly reduced deaths.
Phase-out and bans
The study identifies the complete elimination of paraquat through phase-outs and bans as the most effective approach to saving lives. It highlights case studies from 11 individual countries, along with 27 European Union member states (as of 2007), and 13 West African nations, all of which have enacted bans on paraquat.
Evidence from China, Sri Lanka, and Malaysia shows a marked decline in paraquat-related deaths following the introduction and enforcement of these bans.
These findings align with the hierarchy of control for chemical risk management, which identifies prevention (avoiding registration) and elimination (removing the chemical from use) as the most effective strategies for managing risk and preventing deaths.
Key recommendations
The study outlines several key recommendations to reduce and ultimately eliminate paraquat poisonings and deaths. These include:
- Enhanced surveillance of paraquat poisonings to generate reliable data.
- Regulatory coordination between countries to save valuable enforcement resources.
- Awareness raising to emphasise the need for bans, aiding in implementation and compliance.
- Knowledge sharing on safter alternatives.
- Reclassification from a WHO class II to a WHO class I product, reflecting its high toxicity to humans.
Dr Leah Utyasheva, Policy Director at the Centre for Pesticide Suicide Prevention, who led the study, said:
“There is now overwhelming evidence of paraquat’s toxicity and widespread harm to human health and the environment. This must be treated as a public health priority, with national, regional, and international authorities taking action based on the scientific evidence.
“Our review clearly shows that paraquat bans lead to a significant reduction in deaths. This approach is far more effective than efforts to make paraquat ‘safer’ by changing its formulation or regulations to restrict its use.
“Paraquat needs to be eliminated from use, particularly in countries where it causes the most harm. It is time for governments to prioritize farmers’ health and lives over misplaced concerns about productivity loss and take decisive action to end the use of this dangerous herbicide.”
The study ‘Paraquat at 63 – the story of a controversial herbicide and its regulations: It is time to put people and public health first when regulating paraquat’ is published in BMC Public Health.
Further reading
Malaysia’s deadly pesticide ban has helped prevent deaths, new study suggests
Deadly pesticide’s ‘safety measure’ does not prevent deaths, a breakthrough study shows
Taiwan’s paraquat ban has led to a fall in pesticide suicides, early analysis shows
Paraquat’s ‘safety measure’ based on flawed research, a review of over 30 studies shows