In rural parts of Nepal, acute poisoning with pesticides remains a persistent public health problem. It is the second most common means of suicide nationwide, causing roughly 15 to 20 percent of all self-harm fatalities. Most of these acts are impulsive. In these moments of crisis, household access to highly concentrated agrochemicals can often lead to preventable deaths. 

In August 2019, the Government of Nepal banned eight highly hazardous pesticides. Among them were the neurotoxic insecticide dichlorvos and the three-gram tablet formulation of aluminium phosphide, which comprised 56 percent aluminium. After a two-year grace period that ended in September 2021, giving distributors time to exhaust their inventories, the sale of these tablets became illegal everywhere. By banning them, the government hoped to eliminate an easily available lethal dose and hence to reduce pesticide-related suicides. 

Now, more than five years after the phase-out took full legal effect, comprehensive forensic data reveals that the three-gram tablet ban has produced only a marginal, unsatisfactory decline in phosphine-related suicides. While fatal cases of dichlorvos poisonings have collapsed almost entirely, deaths caused by aluminium phosphide ingestion remain stubbornly elevated. A multi-centre investigation systematically evaluated a total of 2,053 fatal pesticide poisoning cases autopsied between September 2021 and August 2024. The Centre for Pesticide Suicide Prevention (CPSP) at the University of Edinburgh led the research with forensic science laboratories across Nepal, including Central Police Forensic Science Laboratories and the National Forensic Science Laboratory, Khumaltar. 

The forensic data reveals that for three consecutive years through mid-2024, phosphine gas from aluminium phosphide was the leading cause of pesticide deaths. Although overall annual poisoning deaths in Nepal saw a modest reduction from 1,320 in fiscal year 2018-19 down to 952 in 2023-24, the decline specifically tied to aluminium phosphide was minor and statistically insignificant. Furthermore, while 28 percent of analysed cases stemmed from a pre-ban backlog, 67 percent (1,376 deaths) occurred after the grace period ended. These fatalities heavily impacted working-age and youth populations: Men made up 52.5 percent of the victims, and nearly a third (32.7 percent) were young adults aged 16 to 30. Geographically, Bagmati Province recorded the highest share of cases with 25.8 percent, followed closely by Koshi with 20.6 percent and Lumbini with 19.6 percent.

Why does aluminium phosphide continue to be mentioned in postmortem reports, despite the prohibition on three-gram tablets? The prohibition merely affected the form of the dose and not the deadly substance itself. The appearance of phosphine gas in post-mortems could be due to various causes. One cause could be the substitution with non-banned formulations. 

The 2019 directive explicitly prohibited three-gram tablets but left other formulations untouched, including twelve-gram AlP tablets and powdered pouch formulations. In rural agro-vet shops, when farmers ask for a fumigant to preserve stored grain, vendors simply offer unbanned twelve-gram AlP tablets or tear-open AlP pouches. Ingesting any of these non-banned variants generates lethal volumes of phosphine gas; 

Another cause could be absolute lethality and the absence of an antidote. Unlike organophosphates, for which atropine and pralidoxime can reverse toxic effects, phosphine poisoning has no specific antidote. Upon ingestion, it reacts with hydrochloric acid in the stomach to induce profound cellular hypoxia, acute cardiac failure and metabolic collapse. Even minor availability of larger tablets or pouches keeps case fatality rates exceptionally high in district hospitals. 

Yet another cause could be cross-border influx. Because aluminium phosphide is widely manufactured in neighbouring India, the porous southern border enables an unmonitored inflow of unregistered and smuggled formulations directly into the Tarai and mid-hill districts.

Amid this regulatory vacuum, a positive shift has begun on the ground. Nepali farmers are turning away from the dangerous chemical fumigants and are embracing herbal, home-made pesticides to protect their stored grain. Several farming households have turned to using alternative insecticides instead of synthetic poisons. The leaves and seeds of neem (Azadirachta indica), timur (Zanthoxylum armatum), bojo (Acorus calamus), and bakaino (Melia azedarach), mixed with grain and seed samples, are being used as natural insect repellents and antifeedants. The combination of sun-dried grain, wood ash, salt, and mustard oil with mustard extracts is being used to protect pulses and cereals from weevil and borer attacks. 

The Ministry of Agriculture, Forestry and the Environment, the Plant Quarantine and Pesticide Management Centre, and the Ministry for Home Affairs must implement significant actions to convert farmers’ growing preference for chemical-free storage into a nationwide decrease in suicides. A key step involves the government immediately cancelling the registration of all aluminium phosphide products, such as 12g tablets and pouch formulations. To address the formulation loophole, the active ingredient must be removed from open retail markets. Provincial agriculture ministries and municipal extension offices should therefore develop uniform production standards for botanical grain protectants. 

By registering and financially supporting domestically produced, environmentally friendly biopesticides, farmers will be offered safe, commercially viable substitutes for synthetic fumigants. Furthermore, the government is responsible for subsidising the widespread distribution of hermetic storage solutions like multi-layered bags (e.g., PICS bags) and airtight metal containers. Strengthening the nationwide implementation of pesticide laws is vital to curbing the flow of dangerous chemicals. By empowering provincial inspectors and customs officials along open borders to seize illegal agrochemicals, and by imposing strict penalties on unauthorised retail sales, authorities can decisively disrupt the supply of smuggled fumigants.

Over the past seven years, the CPSP has served as an essential scientific partner in Nepal, providing the empirical foundation that made the 2019 bans possible. Recognising the mixed outcomes of the partial 3g restriction, CPSP has already initiated an in-depth implementation surveillance study specifically evaluating the real-world enforcement of the aluminium phosphide ban across Nepal. By actively tracking agro-vet inventories, monitoring clinical hospital poisonings, and analysing post-mortem toxicological casework alongside national authorities, this ongoing CPSP study aims to uncover the exact commercial routes and formulation types keeping phosphine accessible. The hope and objective of this focused surveillance is that concrete, actionable results will soon emerge—providing regulators with the definitive evidence required to close remaining loopholes. 

The ban on three-gram tablets proved that partial measures yield partial results. Farmers have already demonstrated an appetite for organic and non-toxic solutions. By closing the formulation loophole, enacting a blanket ban on all aluminium phosphide products and scaling up alternatives, we can protect both our agricultural heritage and the lives of our most vulnerable.