Lethal mix

Published : Jun 03, 2011 00:00 IST

It is the improper mode of application, violating the law and regulations, that is responsible for the apparent adverse toxic effects of endosulfan.

in New Delhi

FROM a scientific perspective, an extremely pertinent question in the endosulfan story is why adverse health effects similar to those seen in the villages of Kasaragod district in Kerala have not been reported from other parts of the country where the pesticide is used in much larger quantities. The proponents of its nationwide ban, however, do not seem to want to ask this.

Kerala accounts for only about 1 per cent of this now infamous pesticide's total consumption in the country compared with 14.3 per cent in Andhra Pradesh, 11 per cent in Maharashtra, 10.1 per cent in Madhya Pradesh, 9.3 per cent in West Bengal and 7.5 per cent in Rajasthan (map). So is there something unique about Kasaragod district in the context of endosulfan? There is, as will be argued below.

This is the only place in the country where there was aerial spraying of endosulfan. It was carried out by the Plantation Corporation of Kerala (PCK) over an area of about 4,700 hectares (one hectare is 2.5 acres) of cashew crop spread in the vicinity of 20 villages in the hilly terrain of three adjoining divisions (Kasaragod, Rajapuram and Cheemeni) of the district. The spraying had been on continuously for 20 years since 1980, sometimes up to three times a year, until a ban on aerial spraying was imposed in 2001 in the wake of reports of adverse health reactions, including congenital malformations, mental retardation, reproductive disorders, infertility, cancer and neurological disorders. The habitations were in and around plantations, with the Kasaragod division having the largest number of households. According to a report of the Kerala government in 2003, water sources were in plenty in the plantation areas, and one of the streams, Swarga, had its origin in the plantation hills themselves and, hence, the spray-polluted water from the plantations could drain into the stream and nearby wells. The report noted that given the topography and the surrounding population, the area was not suitable for aerial spraying. The spraying was reportedly done without observing the necessary protocols of good agricultural practices (GAP) and safety precautions.

Pesticides are poisonous chemicals and will have minimal effect on the environment only if used in the recommended concentrations. Application beyond safe levels can cause harm to humans and the environment. Unlike the new generation patented chemicals, endosulfan is an off-patent broad spectrum contact' pesticide based on a generic chemical, which controls a host of pests and insects. It is used extensively even by small and marginal farmers in India, where it has been in use since the 1970s. Its current total annual consumption is 12 million litres, which accounts for 17 per cent of the total pesticide use. Even though it needs to be applied in much larger quantities than the new generation ones, it is highly cost-effective. More significantly, it is safe for pollinators such as honeybees and other beneficial insects such as the ladybird beetle, the chrysoperla and the trichogramma (stingless wasps), which is particularly important for fruit and vegetable crops. India is the second largest producer of fruits and vegetables. According to the Indian pesticide industry, India used to import the pesticide until 1980, but today its share in the global market is over 70 per cent, with its total exports valued at about Rs.180 crore.


Endosulfan has been classified by the United States Environmental Protection Agency (EPA) as a Category I (Highly Acutely Toxic) compound based on the LD50 value (a measure of acute toxicity stating the amount of the toxin that kills 50 per cent of the test population) of 82 mg/kg for male rats and 30 mg/kg for female rats under oral and inhalation routes of exposure, and it is less toxic via the dermal route, with LD50 of 2,000 mg/kg (toxicity Category III).

Thus, endosulfan is not a dermal irritant or sensitiser. According to the revised risk assessment of the EPA (2001), endosulfan is neurotoxic and can cause endocrine disorders from acute/long-term exposure. However, it is neither oncogenic nor carcinogenic; that is, it does not cause cancer. It is also not mutagenic or genotoxic. EPA found developmental toxicity (affecting foetuses) only at the highest dose test in a rat study, which also caused maternal toxicity. The EPA study has shown that there is no reproductive toxicity either. According to the EPA's dermal absorption studies in rats, under extended dermal exposure endosulfan is slowly absorbed via the skin and slowly excreted, which suggested bioaccumulation in body fats which in turn can increase the toxicity to target organs.

The World Health Organisation (WHO) classifies it as Class II (Moderately Hazardous) based on rat LD50 of 80 mg/kg, which is roughly the same as the EPA value in male rats. According to the FAO/WHO 2006 Report of the Joint Meeting of the FAO Panel of Experts on Pesticide Residues (JMPR), however, metabolism study of a two-year feeding study in rats showed that endosulfan and the major metabolite endosulfan sulfate do not bioaccumulate in organisms owing to extensive metabolism with enzymatic hydrolysis of endosulfan and the sulfate forming more polar (water soluble) metabolites. The JMPR also concluded that the long-term intake of residues of endosulfan (Acceptable Daily Intake of 0.006 mg/kg) from uses that were considered by the JMPR was unlikely to present a public health concern. As regards short-term intake too (Acute Reference Dose 0.02 mg/kg), the JMPR noted that it was unlikely to present a public health concern.

Since endosulfan is not soluble in water, waterbodies do not transport the chemical as dissolved chemical and hence it is unlikely to enter through drinking water. The chemical persists longer in soil than in water in the form of main soil metabolite endosulfan sulfate and can thus be transported as part of run-offs. However, from the soil it is not expected to enter the food chain since it is not absorbed by plant roots. Endosulfan is biodegradable and the degradation is quick 92 to 97 per cent dissipates in a month and the half-life of the residue endosulfan in tropical climate is significantly shorter (anywhere from seven to 42 days depending on the crop and different Indian climatic conditions) than in temperate climates of Europe (75-93 days). Residues of endosulfan in soil under Indian climatic conditions have been found to persist for 60 days with a half-life of 10-11 days.

Aerial spraying

A plausible explanation for the range of observed health effects in Kasaragod is the indiscriminate aerial spraying of endosulfan. Though risk evaluation of endosulfan is still evolving with better understanding of host interactions, the diverse effects reported in Kasaragod are a great deal beyond the documented effects of acute toxicity as discussed above. At present this association is, as the Kerala government report says, at best more by way of elimination of other possible causes. This assumed causal link with endosulfan needs to be established by a properly designed epidemiological study. This, unfortunately, has not happened till date despite media reports that began to surface about a decade ago.

The report of the National Institute of Occupational Health (NIOH) of the Indian Council of Medical Research (ICMR) in 2001-02, which carried out a study in Padre village of Kasaragod division following a directive from the National Human Rights Commission (NHRC) to the ICMR in 2000, found an apparent linkage from the pesticide residue levels detected in the ecosystem of the region. This was, however, found to be seriously flawed by several expert groups that analysed the study when the pesticide industry picked several holes in the report. Most importantly, there was a substantial time gap between the last exposure and the NIOH study period and, therefore, it may not, for example, reflect accurately on the relationship of endosulfan exposure to the various observed health effects.

Even though the hilly terrain of the crop area with steep slopes is favourable for high run-offs of any aerially sprayed toxicant to accumulate in the water-soil system surrounding the villages in the downhill area and cause chronic toxicity from long-term exposure, the recently released report of the Health Ministry of the Gujarat government has pointed out that the exposure levels would still have been less than what workers in an endosulfan plant would have been exposed to. There have been no reported health disorders from the major manufacturing units of endosulfan in Gujarat. However, this observation needs to be taken with a caveat because, as V.M. Katoch, Director-General of the ICMR, points out, because of good manufacturing practices (GMP) in a factory environment the exposure levels are likely to be lower than in field conditions of indiscriminate spraying in open plantations.

It is also possible that people of the area are nutritionally or genetically predisposed to being highly vulnerable to long-term endosulfan exposure. Only a detailed and sound epidemiological study can provide answers to these questions. But this may not be a straightforward exercise, especially because Kasaragod is also an intense vegetable- and banana-growing area where other pesticides are also in use. So, discriminating the effects of endosulfan from the others can be problematic. But, perhaps now, this may be possible following the suspension of endosulfan usage. Indeed, following the present outcry against endosulfan, a new inter-disciplinary committee has been constituted under the ICMR for undertaking a new study. According to Katoch, this study, which will be carried out with the help of local medical colleges, will compare the data from earlier studies and see if the key medical issues supposedly arising from acute and/or long-term endosulfan exposure have declined in the 10-year period since aerial spraying was stopped in December 2000.

The study will also look at the utilisation patterns of endosulfan in other parts of the country by involving the Indian Council of Agriculture Research (ICAR) in the committee. The development of protocols for the study, which Katoch says will be robust, is to be completed by July and the study itself is to be completed in two to three years' time. Meanwhile, a second survey of the affected area by the Kerala government, carried out with the help of Calicut Medical College, is about to be completed.

Y.K. Gupta Committee

Since endosulfan is a broad spectrum pesticide which is known to degrade quickly in the environment, its use against tea mosquito in cashew crops is legitimate and, in fact, its use on cashew is approved. But the question is whether aerial spraying was legitimate. The most pertinent observation with regard to the spraying operations undertaken by the PCK was made in a report by the Y.K. Gupta Committee (2006), which was one of the expert committees constituted by the Ministry of Health and Family Welfare (MOH&FW) in the wake of the controversial NIOH report. This observation has not been given the attention it deserves in the endosulfan debate.

The following are the three registered formulations of endosulfan in India as approved by the Central Insecticide Board (CIB) under the Insecticides Act (1968): 35 per cent emulsifiable concentrate (EC), 4 per cent dusting powder (DP), and 2 per cent (DP) for controlling insect pests attacking various crops including rice, wheat, jowar, pulses, sugarcane, cotton, jute, maize, vegetables, tobacco, cardamom, tea, coffee, cashew, mango, cocoa, citrus, groundnut, mustard, safflower and sesame. For hand spray and high-volume machine spray, which are the normal modes of application of the pesticide in India, a Kerala Agriculture University (KAU) document apparently states the following prescription for application: 35 per cent EC diluted in water to 0.05 per cent.

For aerial spraying of any pesticide, says the Gupta Committee report, an ultra low volume (ULV) formulation has to be employed. Secondly, the permission of the CIB is mandatory before undertaking aerial spraying of a pesticide for agricultural use. ULV formulation of endosulfan in use globally is usually 1-2 per cent concentrate diluted to 0.05 per cent. But no ULV formulation applicable for aerial spraying has been registered by the CIB in the country. Also, India neither produces ULV formulation (for export) nor imports it, according to Agriculture Ministry sources. So did the PCK use the high 35 per cent EC formulation for aerial use? This is the most important question that needs an answer to get an idea of what kind of endosulfan dosage levels were the people around the plantations exposed to. But, unfortunately, this information is not available in any of the committee reports that have been made public. Also, most significantly, the CIB confirmed to the committee that no permission for aerial spraying was sought from it.

Solubility of endosulfan in water is very low; it is 0.32 mg/l at 20 {+o}C. Emulsified concentrate formulations are used because of this immiscibility property of endosulfan. If a formulation not designed for aerial spraying is used, it can present problems such as thickening, excessive foaming and emulsion inversion (phase inversion), points out the document Good Practice for Aerial Application of the Food and Agriculture Organisation (FAO). Emulsion inversion can result in the separation of the two immiscible phases in the emulsion pesticide concentrate droplets from water. Further, since aerial spraying is not a common practice in the country, it is not clear whether the PCK followed the guidelines for aerial spraying, in particular using helicopters, because there are inherent disadvantages of aerial spraying compared with conventional spraying, and the usage of choppers requires additional considerations.

As the FAO document notes, high wind speed and temperature inversion may limit treatment application. Accurate deposition in dense crop canopies can also be more difficult to achieve with aircraft. Volatility and spray drift can be a problem with aerial spraying and environmental contamination can be significant if spraying is incorrectly executed. Normally, aerial spraying is done from a height of five to 10 metres above the canopy. According to one industry source, helicopter spraying can achieve better pesticide deposition on the foliage because the leaves turn upwards because of the vertical wind movement when the helicopter hovers. But, according to the Kerala government report, because of other tall trees in the plantations, the helicopters were flown very high and this could have resulted in wider dispersal than desired.

This also ignores one other important consideration, which is the stability of the emulsion that can be significantly affected in aerial spraying if the formulation is not suitable for aerial spraying. Under environmental conditions of high temperature, wind velocity, turbulence and wind shear instability can set in, causing non-uniform mixing of the emulsion and even phase separation, resulting in inefficient deposition and wide dispersal of the pesticide. In fact, any stress can result in the separation of the phases, and this consideration becomes important if it is a more potent emulsifiable concentrate.

Emulsion instability and phase separation in a higher concentration formulation such as 35 per cent EC can result in the deposition and dispersal of high-concentration pesticide droplets in the environment. This problem will be worse if there is coalescence instability combining of smaller droplets to form bigger ones as well. Even though endosulfan is known to degrade quickly, dispersal of high-concentration pesticide droplets in the ecosystem would obviously lead to a greater dosage to the population in a short period, which may be the cause for the severe morbidities. It is not clear if the different committees have looked at the specific issues that can arise from the aerial spraying of inadmissibly high concentration formulations. If epidemiological studies do conclusively establish a causal link with endosulfan, the arguments above also probably answer why such effects have not been seen elsewhere.

But, unfortunately, the focus of the entire debate is as if the culprit is the chemical. It is the improper mode of application that is violative of law and regulations which is responsible for the apparent adverse toxic effects of endosulfan. And the culprits are the government of the late 1970s and early 1980s trial aerial sprays had begun in 1977-78 itself that first allowed aerial spraying by the PCK in blatant violation of regulations, and successive governments that allowed this to continue. This also clearly points to a weak regulatory system at the Centre under the CIB.

E.U.'s manipulations

Interestingly, the Kerala government is the one that is now calling for a nationwide ban on the chemical, and V.S. Achuthanandan as Chief Minister even managed to put enormous pressure on the Ministry of Environment and Forests (MoEF) to soften its position on endosulfan at the Stockholm Convention on Persistent Organic Pollutants (POP) even as the Indian delegation was negotiating at Geneva at the 5th meeting of the Conference of the Parties (COP5) during April 25 to 29. As we shall see now, the decision of the COP5 to include endosulfan in Annex A the list of pesticides to be phased out is entirely because of the manipulations of the proceedings by the European Union (E.U.). In fact, the entire endosulfan issue in the context of the convention has been driven by the E.U. after being a leading manufacturer of endosulfan for 55 years. It was used in European countries until 2005 without any reports of adverse health impact.

With the development of new patented pesticides to replace endosulfan, the E.U. decided in 2001 to phase out endosulfan. In 2005, the E.U. withdrew all authorisation for the use of plant protection formulations containing endosulfan. European (predominantly German) manufacturers stopped the manufacture of endosulfan in 2007 but continued to sell the product from the stocks.

On July 26, 2007, the E.U. submitted a proposal to the convention for considering endosulfan as a POP. One of the requirements for this is that the proposed chemical should meet the criteria in Annex D of the convention. In particular, Annex D requires that the half-life of a chemical in water is greater than two months or that it is greater than six months in soil, evidence that there is long-range transport of the chemical and evidence of significant adverse effects to human health or to the environment. The mandate of the POP Review Committee (POPRC) is to evaluate if the proposed chemical meets the requirements of Annex D. Given the observations of WHO/FAO on half-life and its health effects as well as validated data from tropical regions of the world, it is clear that endosulfan does not meet the criteria of Annex D.

And yet in September 2007, the convention secretariat published a document stating that [the] Secretariat was satisfied that EU's proposal met the requirement of Annex D. In POPRC-3 in November 2007, the E.U.'s proposal was listed for examination. However, POPRC-3 did not examine the proposal but noted in its final report, in obvious contradiction to the earlier document, that vital information required for consideration of endosulfan had not been made available to it.

It asked the E.U. to supply the vital information for consideration in POPRC-4, in violation of Article 8 of the convention which states that incomplete proposals be set aside by the POPRC. In its position paper submitted at COP4 in May 2009, India stated: Decisions made by POPRC-3 and POPRC-4 on EU proposal be not confirmed and POPRC revisit the entire issue in accordance withthe Convention.

Between POPRC-3 and POPRC-4, the proposal was amended and it was introduced at POPRC-4 in October 2008, but by an observer from the E.U. who was not a member of the POPRC, a Spanish private consultancy firm, in contravention of COP rules. At POPRC-5 in October 2009, sufficient evidence could not be brought out to establish the requirements under Annex D.

Further, while reviewing the E.U. proposal, substantive decisions were taken by majority votes and not by consensus as required by COP rules. All these, India said in a dissent note submitted at POPRC-6 in October 2010, undermine the integrity and principle of procedural fairness of the multilateral convention. Besides, it contains a strong element of conflict of interest. At POPRC-6, India pointed out in its position paper that the Risk Management Evaluation (RME) report, which was based on only inputs from eight of the 172 parties, was not robust and was also incomplete. Further, the alternatives suggested had not been assessed for non-POP properties such as persistency, bioaccumulation, long-range transport and adverse effects and also that most of the alternatives were narrow spectrum pesticides that would result in high costs for Indian farmers (Table 1).

India also reiterated its stand that unless its procedural and substantive concerns were addressed suitably, no decision on the E.U. proposal, which was deeply flawed and deficient on many counts, be taken. And yet, POPRC-6 recommended the listing of endosulfan as a POP.

In its position paper at the recently concluded COP5, India reiterated that important procedural violations had occurred and substantive issues had not been addressed. It also pointed out the lack of scientific evidence in accordance with Annex D for endosulfan to be included as a POP in Annex A and listed the counter-evidence available from the world over, in particular WHO/FAO reports.

As regards safer alternatives, it pointed out that many alternatives suggested had POP characteristics exceeding those of endosulfan. For 78 out of 85 chemicals suggested, the relevant data on persistence were not provided. As many as 22 alternatives had more bioaccumulation potential than endosulfan. Others had higher mammalian toxicity and showed suspected carcinogenicity and genotoxicity.

India's initial position was that the recommendation of POPRC-6 concerning endosulfan be set aside. However, under intense political and activist pressures, in particular from the Kerala Chief Minister, the government asked the delegation not to obstruct the decision, given the flexibility available in the convention for a phase out and given the long-term perspective that the country should move towards safer and milder alternatives continually. And thus India became party to the draft decision (SC-5) that lists endosulfan, its related isomers and endosulfan sulfate in Annex A as a separate part VI of the Annex.

For parties such as India that have chosen to avail themselves of the provision of opting in or out of any COP amendment under Article 25.4, the amendment goes into force after the 90th day of its deposition of instrument of ratification of the said amendment. In that sense, India still has the sovereign option of not ratifying the amendment if required. But it is unlikely that India will exercise that option, given that there is a window of 11 years for phasing out endosulfan, during which time India should be able to develop its own generic alternative through domestic R&D.

Any amendment to the Annexes comes into effect one year after the COP decision. Also, Article 4 of the convention allows any party to seek exemption against elimination and continue producing and/or using endosulfan, and the COP decision has given specific exemption against a list of crop-pest complexes (Table 2 ).

Article 4.4 states that these exemptions will expire five years after the entry into force of the COP decision, and Article 4.7 allows a further exemption for five years upon request from a party on account of the special circumstances of the developing country parties. So, in effect, if India ratifies the decision, it will have a window of 11 years for phasing out endosulfan.

However, Table 2 shows a final twist to the whole tale; the list of exemptions does not include cashew! It is not clear whether this was a conscious decision of the government or whether it was an ironic oversight.

According to the MoEF, the exemptions sought by the country were in accordance with the information provided by the Ministry of Agriculture. While it is true that endosulfan use in the country for cashew crop is very small and that the largest grower, Kerala, has already banned it, there are other important cashew-growing States on both the west and east coasts, where a drop in productivity because of pest infestations has been seen. So these States will not legally use endosulfan for cashew unless India decides to seek an addition to the exemption list or chooses not to ratify the amendment to Annex A.

Sign in to Unlock member-only benefits!
  • Bookmark stories to read later.
  • Comment on stories to start conversations.
  • Subscribe to our newsletters.
  • Get notified about discounts and offers to our products.
Sign in


Comments have to be in English, and in full sentences. They cannot be abusive or personal. Please abide to our community guidelines for posting your comment