Kerala’s Endosulfan Tragedy

Page 1 of 1
Did it really happen? A lesson in how India handles scientific debate

Mohammed Asheel is a fast talker. The nodal medical officer of Kasargod district, who played a key role in Kerala’s campaign against the pesticide endosulfan, refuses to answer my questions until I see a slide-show on the toxic effects of this chemical. Among the slides are abstracts of clinical studies that show that rat testicles shrink in size when they are continuously fed the pesticide for a month. Another study suggests a link between endosulfan and autism among children in California. Asheel’s talk is peppered with words such as ‘gaba receptors’ and ‘COPD’ (Chronic obstructive pulmonary disease), medical terminology that will throw most lay people off.

Even after he begins answering my questions, he dodges a few. The first question he dodges is: how many different diseases are being considered as part of aid to victims of endosulfan? At last count, there were over 300. In the first round of medical camps for victims in Kasargod, people with diseases such as jaundice, depression, hearing loss, epilepsy, and even those with non-diseases such as limb amputation, were classified as endosulfan victims and given government aid. Lump sums of up to Rs 5 lakh, a monthly social-security allowance of Rs 1,700 and medical treatment were given to around 4,000 patients.

It takes a while for Mohammed Asheel to admit this, but he does: “To be frank, in phase 1 camps, identifying victims was left to the discretion of the doctors, because we were unaware of all the diseases that can be related to endosulfan.” According to Asheel, doctors may have exercised their ‘humanitarian discretion’ and not just their medical discretion. So far, several hundred crore have been disbursed to so-called endosulfan victims in Kerala, with very little proof that the pesticide was indeed the cause. This is a major political issue now, and Kerala’s political parties ignore it in the upcoming elections at their own peril. But the list of bogus victims taints this massive campaign against the pesticide and raises a crucial question. Was science co-opted to suit political interests?


The endosulfan controversy first began in the late 1990s.

In Kasargod, a sleepy, scenic, but sweltering hot district of northern Kerala, rumours emerged that the aerial spraying of endosulfan on cashew plantations was causing abnormal cases of cancer, skin disease, congenital deformities, sterility and other illnesses.

As time passed, local activist groups grew increasingly convinced that they were being caused by a very old off-patent pesticide of the organochlorine class, to which the notorious DDT belongs. For 20 years, this pesticide—endosulfan—was aerially sprayed on thousands of hectares of hilly cashew plantations in Kasargod. Environmentalists and denizens of this district began to believe this spray was slowly poisoning people.

By 2001, the issue became big enough for the Kerala government to ban endosulfan. The Indian and global media began overdosing on the horror of the tragedy, implicating endosulfan in a shockingly wide range of diseases—from mental retardation to hydrocephalus, a disease which causes the head to swell to the size of a large watermelon. In January 2012, The Guardian ran an article saying half the homes in the village of Kattuka (Kattukukke misspelt) in Kasargod had a disabled person—a gross exaggeration.

Meanwhile, an association of countries grouped under the Stockholm Convention, which aims to eliminate the use of dangerous chemicals in the world, called for a global ban on endosulfan in 2009. The events of Kasargod played a role in this decision, with green groups such as Pesticide Action Network and Thanal campaigning worldwide with horror-inducing pictures. The best known image among them is a picture of a child with hydrocephalus. This picture may well be the face of the global anti-endosulfan campaign, just as Pablo Bartholomew’s photo of a partially buried child became the face of the Bhopal gas tragedy.

But what really happened in Kasargod is not very clear.

As much as activist and political groups want endosulfan to be India’s DDT, it is far from proven that the pesticide indeed caused the diseases seen in Kasargod. It is not even proven that Kasargod suffers from a higher incidence of these diseases.

As of today, the endosulfan issue is more of a political debate than a scientific one.

Several of the people being compensated today have diseases that have nothing to do with endosulfan, such as deafness and diabetes. Government doctors admit this, saying they experience pressure to include people in the endosulfan- affected list. “‘Your son has a disease due to endosulfan’— people like to hear this,” says a government doctor who wishes to remain anonymous.

Keshava Naik, a civil surgeon who has worked in Kasargod for almost 20 years, says that before 2000, the government was only offering treatment for the endosulfan-affected. No compensation was being paid then. “Not many people were coming forward for treatment then,” he says. “But now, people are fighting to be included in the victims list.”

According to Naik, doctors in Kasargod are confused because they have no scientific guidelines to identify victims. As a result, in the first few medical camps, anyone could walk in and get government aid.

“So far this is only a political issue,” says Naik, “We medical people have had no role in this.”

Meanwhile, Manoj Kumar, secretary of the Kerala Government Medical Officers’ Association, says only that “it is a controversial issue. We have to follow the government’s policy and toe the line. So I cannot give a straightforward answer.” Several of the other doctors I spoke to were unwilling to go on record against the official policy line. Off the record, though, they call the entire process a sham.

A government doctor who worked in Kasargod for six years, said, “In my panchayat of 22,000 people, no more than 300 people had diseases. I couldn’t see any ‘abnormal’ occurrence.”

This is the crux of the dispute. Government doctors say the incidence of diseases such as cancer, cerebral palsy and hydrocephalus is no higher in the district of Kasargod than in the rest of India. It is an accepted medical fact that in any given population, 1-2 per cent of the people have congenital disease by pure chance alone. And the occurrence of several diseases in villages close to the sprayed plantations is below this threshold.


Sitting behind a desk covered with stacks of paper in Kasargod’s Kerala Agricultural University, is Kinavoor Madathil Sreekumar, an associate professor of entomology—the study of pests and pest control. He is one of the few people willing to go on record against what he calls ‘one of the biggest scientific frauds’ he has seen. In one of the several emails exchanged with me before we met, he proclaimed in capital letters, ‘The endosulfan king is naked.’

In his youth, Sreekumar, the son of a farmer, was a huge proponent of organic farming. He was friends with the same green activists with whom he is at loggerheads today.

When rumours about endosulfan emerged in the 1990s, Sreekumar began investigating if they were correct. By the time the ban was imposed in 2001, he was convinced they weren’t. Several of the local doctors who spoke to him were highly cynical of what was being reported. “It opened my eyes,” says the entomologist.

He shows a table comparing the rates of diseases such as mental retardation, cerebral palsy and hydrocephalus in the district of Kasargod with those of the rest of India. In no case do Kasargod’s numbers exceed India’s national averages. The only exception is the village of Padre, which has a higher rate of mental retardation and reproductive disorders. “But this could be due to some other reason that we don’t know. If it was due to endosulfan, why didn’t this happen in all villages close to the cashew plantations?” he asks.

Then there are villages far from the cashew plantations which also see a high rate of disease, such as Mogral Puthur. “What is the cause of this?” Sreekumar asks. The health department has no interest in finding out real culprit—“if one exists,” he says. Sreekumar’s point is that no one has made an attempt to scientifically study the real reasons that may have contributed to such spikes in disease rates. Endosulfan has been an easy target.


In the past ten years, several studies were carried out to find out if endosulfan was truly the cause of these diseases, and if they were indeed more common in Kasargod. But each of these studies had major flaws—a reflection of the quality of research by India’s premier science organisations.

Among the very first was a study by the Delhi-based environmental activist group Centre for Science and Environment (CSE). This study claimed that endosulfan levels in the blood of Kasargod’s ill residents were extremely high. But the blood levels CSE reported, at over 100 parts per million, were not just high, they were unbelievable. No living animal can survive such poisoning. Even suicide victims, who swallow endosulfan deliberately, have less than 10 parts per million in their blood.

Recognising this blooper, the National Institute of Occupational Health (NIOH) carried out another study in 2003 to determine if the problems in Kasargod were indeed caused by endosulfan. This study too was shot down, not just by pesticide manufacturers, but independent scientists such as Sreekumar. In response to the many flaws in the NIOH study, the Calicut Medical College (CMC) was commissioned to undertake a study with guidance from India’s reputed Indian Council for Medical Research (ICMR).

This study, published in 2011, was no huge improvement.

To understand its flaws, I approached Prem Mony, who heads the division of epidemiology at St John’s Research Institute in Bangalore. Mony began his response to me by saying, “This study has so many loopholes, I feel I should write a critique on it myself.”

According to him, the CMC study is what is called a cross- sectional study—it shows association but not causation. This means that even if the study picks up the existence of a higher rate of disease in the villages, it does not prove that it was caused by endosulfan.

Mony narrates the plot of a movie to explain the difference between association and causation. A married couple is staying with the husband’s parents. When they are asleep at night, a burglar breaks in. At about the same time, the wife wakes up and comes to the kitchen to drink water. Out of fear, the burglar stabs the wife. When she screams, the husband comes in to help her. Just as he reaches her, the rest of the family rushes in and sees the scene. They think the husband has murdered her and take him to the police station.

Mony’s point is that a cross-sectional study is vulnerable to exactly this kind of faulty conclusion.

Even if the CMC study did spot a high incidence of disease in Kasargod, it cannot say it was caused be endosulfan. To prove it, longer more complicated studies such as case-control studies or cohort studies would have to be conducted. But that is not all that is wrong with the CMC study.

According to a critique by Sreekumar and fellow entomologist Pratapan Divakaran, published in the magazine Current Science, the levels of endosulfan in the blood of patients in the CMC study seem to have no correlation with the health of these patients. This means higher endosulfan levels did not lead to higher rates of disease.

Mony explains that measuring exposure to the pesticide—whether through air, soil or blood levels—is vital to a good epidemiological study. Without measuring the exposure level, the results of the study are meaningless. The CMC study also does not specify the method it followed to arrive at a meaningful sample, a critical requirement for a good study.

“For public policy decisions to be taken, a peer-reviewed and published study should have been used,” says Mony, pointing out that the CMC study wouldn’t pass muster if taken through a peer-review process.

My chat with Jayakrishnan T, one of the authors of the CMC study, ends halfway when he says he is only answerable to epidemiologists. When I ask an ICMR official how the Council could allow such a poor quality study, he says the body does not take ownership of the study, and while he tries to address some of the loopholes, he leaves other questions unanswered. (1)


Mohammed Asheel too admits that the CMC study is flawed, and that non-victims were wrongly compensated. But to him, this doesn’t change anything, because he believes the fault with the CMC study lies only with data analysis.

As for the bogus victims, he says his team is learning from the mistakes of the first round. According to him, a few cases of misclassification don’t mean there are no victims. “If there is a problem in the BPL (below-poverty-line) list,” he argues, “that doesn’t mean there is no poverty. It only means that the system of classifying BPL people needs to be improved.”

He insists that the problem of misclassification in the first medical camp has now been addressed. In the future, Asheel says, patients will be selected for the camp based on the ‘biological plausibility’ of the disease they have. When I ask him what biological plausibility means, he points to studies in rats and mice where endosulfan has been shown to produce cancers and reproductive disorders.

Here is the problem with this approach:

First, rat models often do not translate to human beings. So if a rat study shows that endosulfan causes tumors, it doesn’t mean it will cause tumors among humans. Mithua Ghosh, a senior researcher at the HCG group of cancer hospitals, says animal studies are merely the first step towards showing how a chemical will affect human beings.

Second, there are rat studies that indicate the opposite—that endosulfan does not cause tumors.

The scientific process requires that the results of any study be reproducible. This means that each time a study is carried out, it should yield the same result—in this case, that endosulfan causes tumors. Only then can it be said that endosulfan causes cancer in rats. This is why a single study is never enough to establish a fact.

Asheel also shares another study that links prostate cancer among men with exposure to several pesticides such as endosulfan and DDT. Such a study cannot conclude that endosulfan is a carcinogen, because the people being studied are also exposed to several other pesticides. This is perhaps why neither the World Health Organization, nor the American or Australian regulatory authorities classify endosulfan as a carcinogen.

But absence of proof is not proof of absence, argues Asheel. While it is a good argument, it opens a whole new can of worms. By this token, there are hundreds of chemicals that we use daily that show similar inconclusive signs of carcinogenicity. Take malathion for example, a very old pesticide known to be relatively safe for humans. The Stockholm Convention has suggested malathion as one of the alternatives to endosulfan for use by India. There are several published studies that indicate that malathion can cause cancer, and similarly, there are several that indicate it doesn’t. The WHO, therefore, concludes that there isn’t enough data to say malathion is carcinogenic.

Closer home, there is paracetamol, the ubiquitous pill we don’t think twice before popping for fevers and colds. There exists one study linking paracetamol to a higher incidence of liver cancer. And then, there exist hundreds which show absolutely no link. It would be ridiculous, therefore, to say paracetamol causes cancer based on a single study.

The Kerala government, of course, hasn’t blamed only cancer on endosulfan. It has linked a mind-boggling variety of diseases—ranging from autism to sterility to mental retardation—to a single chemical. In most cases, the evidence is vague and tenuous. For example, a study showing that endosulfan may affect the occipital lobe, the visual processing centre of the brain, is taken to mean that endosulfan causes blindness.

Mony dismisses this approach for identifying victims as ‘balderdash’. “If they want to give compensation as a precautionary measure for political reasons, let them say so. I have no problem with that. But let them not say it is based on science, because the science on which [it is] based is junk,” he says.


In 2009, when the Stockholm Convention classified endosulfan as a persistent organic pollutant, or POP, things got complicated for India.

POP is a bit of a bad word.

It means that endosulfan is classified along with notorious pesticides such as DDT and Dieldrin because of certain characteristics—a tendency to remain in soil without degrading for long periods of time, to accumulate in the bodies of living organisms, and to travel across long distances and cause harm to living beings.

Activist groups were quick to jump at the Convention’s decision to justify their claims that Kerala’s diseases were caused by endosulfan. According to them, POPs are toxic. So everyone in Kasargod must have fallen sick due to endosulfan.

This simplistic argument has confused many. But it doesn’t hold weight.

For one thing, the Convention’s decision is by no means beyond scientific debate. Perhaps one of the biggest critics of this decision is Ivan Kennedy, an environmental chemist at the University of Sydney, who has called it ‘bad bad science’.

His argument boils down to one single point: around 95 per cent of the world’s usage of endosulfan today occurs in tropical climates such as India where the concentration of insects and pests is very high. And in hot tropical climates, endosulfan does not behave as it does in cooler temperate climates. It neither remains in soil for long, nor does it accumulate in the bodies of large mammals. This brings down the likelihood that it would affect human health, because the faster a pesticide disappears from the environment, the less people are exposed to it.

Kennedy, who has published a large body of research on endosulfan, alleges that the Convention cherry-picked data from laboratory studies and arctic studies, which do not reflect field conditions in countries like India and Australia at all. Most scientists agree with Kennedy’s point. Crispin Halsall of the Lancaster Environment Centre in the UK, who advised the Convention on its decision, agrees that endosulfan behaves differently in tropical climates. Another German scientist, Volker Laabs, whose study was cited in one of the Convention’s documents, also says that the pesticide’s behaviour makes ‘long-term accumulation in tropical soils under realistic field conditions not very probable.’


What does all this say about the Kasargod experience?

Let’s reconstruct what happened over those 20 fateful years when endosulfan was used in Kerala. On two days each year, endosulfan was sprayed on cashew plantations from a helicopter. The formulation that was sprayed contained about 0.05-0.1 per cent of endosulfan, a small amount to begin with.

From the studies carried out by scientists such as Laabs and Kennedy, we can picture the following scenario: Endosulfan falling on leaves would degrade within a mere 15 days in the hot weather of Kasargod, unlike other POPs such as DDT. In soil, the chemical would degrade in less than a month. Some pesticide would fall into ponds and wells, but would settle to the sediment at the bottom, since endosulfan has low solubility in water. This, too, would get degraded within a month. Villagers drinking the water would therefore probably not consume the pesticide.

Meanwhile, a human exposed directly to the spray would get less than 1 per cent of what amounts to a lethal dose of endosulfan, the dose that can cause death. But his or her body would quickly excrete anything entering it.

A small part of the endosulfan would get converted to another compound, endosulfan sulfate, which is a more persistent chemical. But human exposure to the sulfate would be about a thousandth of the exposure to endosulfan.

Again, the spraying occurred on only two days each year.

But this is merely a reconstruction. What if we look at examples of endosulfan sprayed elsewhere in India? It turns out that cotton farmers all over India have used the chemical for many years. Unlike in Kasargod, these farmers spray endosulfan using handheld sprayers, meaning they are likely to be exposed to more of the chemical. And yet, there haven’t been reports of disease epidemics among these farmers.

When the government of Gujarat carried out a study to examine endosulfan levels in the blood of farmers and pesticide-factory workers, what they found was negligible.

Then again, aerial spraying is different from hand spraying, say activists. In this case, India can look towards Australia, another hot country, for a real-life example.

In parts of Australia, when insect pressure was high in certain months, endosulfan was sprayed as often as five to six times in less than a year. Despite years of spraying at much higher frequencies, no health effects on humans were reported. This is confirmed by Bruce Pyke, an official from Australia’s Cotton Development Corporation Council.

Why, then, is Kasargod the only place in the world that believes it has been affected by endosulfan?


It is easy for India to assume that pesticide manufacturers are always evil. In the DDT case, pesticide manufacturers argued against data demonstrating its harmful effects, and resisted a ban for years. The Bhopal Gas Tragedy ensured that Indians have no faith in the regulatory system.

Meanwhile, the Plantation Corporation of Kerala, which owns these cashew plantations, did not exactly act with scrupulous care while applying the pesticide. In the first three or four years, water bodies in the sprayed areas were not covered, and only after local people protested did the company start distributing covers for wells and informing villagers in advance. This muddies the waters.

The question is no longer whether India should ban endosulfan. India can well choose to accept the Stockholm Convention’s decision and discontinue the use of endosulfan as a precautionary measure. “Let them ban it using the principle of abundant precaution if they want,” says Sreekumar, “But let them prove properly that all these diseases were really due to endosulfan.”

Perhaps the biggest losers in this entire controversy are the stigmatised residents of Kasargod themselves, despite the large sums of money they have received from the government.

Men and women in this area are now finding it difficult to find spouses, as stories of their tainted genes get around. Some want to sell their land and move elsewhere, but the belief that the soil is poisoned ensures that they will get only throwaway prices.

There is also an epidemic of fear, says Sreekumar. When children develop a slight headache, mothers worry that this may be the onset of hydrocephalus. Meanwhile, the truly ill will never know the real cause of their diseases, as endosulfan has been turned into everyone’s favourite whipping boy.

But the residents of Kasargod are finally hitting back. Around two weeks ago, tired of the lies of the media and politicians, an organisation called Endosulfan Apamaana Vimochana Samiti was formed. Its name literally means ‘Association to fight the insult of endosulfan’ and ‘insult’ refers to what has been meted out to the local community, which is how these residents view the social stigma that blights Kasargod.

This article has been modified after it was published