Applying the Precautionary Principle in the Risk Assessment of Pesticides:
Endosulfan Case Study

Romeo F. Quijano, M.D.
Department of Pharmacology and Toxicology
College of Medicine, U.P. Manila, Philippines


Historically, the introduction of synthetic chemicals to the environment had always been perceived initially as safe and generally without serious adverse impacts. The apparent economic and consumer benefits tended to ignore whatever warning signals there were. During the last few decades, however, evidence of the devastating impacts of many toxic chemicals, including pesticides, have steadily been increasing and left no doubt that we can no longer ignore the threats to health and environment that these toxic chemicals bring. The failure of science and regulatory systems to adequately predict the potential harm and to institute effective measures to prevent harm has contributed to the dangerous situation that the environment is now in. This failure is due in part to a reductionist scientific paradigm that largely ignores the the broad inter-relationships of the ecosystems and the infinitesimal uncertainty factors that often preclude demonstration of cause and effect relationships and probabilistic characterization of risks. To be meaningful, an assessment process looking into the potential environmental and health impacts of a chemical or activity should put primary emphasis on the objective of protection and not on the presumption of innocuousness or tolerance. It is important to examine the full range and multiplicity of the potential impacts and to engage in a broad characterization of need, alternatives, and the full spectrum of the potential threats to health and the environment based on existing data. This exercise should lead to concrete recommendations for actions that would seek to prevent or mitigate the potential adverse impacts without waiting for the generation of additional data to fill-in identified data gaps or uncertainties.


To illustrate the process described above, an enhanced risk assessment of endosulfan is presented below. This assessment process uses the precautionary principle as a framework but employs the elements of the “risk assessment” methodology to guide the overall evaluation.

Step 1. Identifying the possible threat and characterizing the problem

A. Background information on endosulfan

Basic information

A. Molecular structure: C9H6Cl6O3S

B. Chemical name: 6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-

C. Derivatives: endosulfan sulfate, alpha and beta isomers(4:1)

D. Molecular weight: 406.95 g/mole

E. Solubility in water: <1.0 mg/l

F. Common physical appearance: brownish crystalline solid

G. Oral LD50(rat): 18-43 mg/kg

H. Pesticide classification: organochlorine insecticide

I. Hazard Classification: EPA – Class I
WHO – Class II

This powerful insecticide is a member of the organochlorine class of pesticides, fathered by the now widely banned DDT (dichlorodiphenyltrichlorethane). It is chemically very closely related to Dieldrin, substituting a heterocyclic sulfur in place of the saturated bicyclic ring system. Organochlorines alter both sodium and potassium concentrations in neurons, affecting impulse transmission and causing muscles to twitch spontaneously. Many of the organochlorine insecticides were found to be very toxic to all forms of wildlife early in their use history. Endosulfan earned a bad reputation for an accidental fish kill in the Rhine River in 1969. As a consequence of their extreme toxicity and the fact that they also persist for a long time in the environment, organochlorines are gradually being phased out.


Endosulfan is a chlorinated hydrocarbon insecticide and acaricide of the cyclodiene subgroup which acts as a poison to a wide variety of insects and mites on contact. It is used primarily on a wide variety of agricultural crops including cotton, tea, coffee, fruits, and vegetables, as well as on rice, cereals, maize, sorghum, or other grains. Formulations of endosulfan include emulsifiable concentrate, wettable powder, ultra-low volume (ULV) liquid, and smoke tablets. It may be found in formulations with dimethoate, malathion, methomyl, monocrotophos, pirimicarb, triazophos, fenoprop, parathion, petroleum oils, and oxine-copper. Technical endosulfan is made up of a mixture of two molecular forms (isomers) of endosulfan, the alpha- and beta-isomers.

Endosulfan was first made available for use in most countries in the 1950’s when risk assessment process, or any safety evaluation procedure for that matter, as a requirement for pesticide registration was not yet in place. In the Philippines, even at the time that the Fertilizer and Pesticide Authority (FPA)was created in 1977, endosulfan was registered with the assumption of safety without any rigorous evaluation of potential risks. In the early 1980’s, risk assessment began to be considered in pesticide regulation coinciding with the establishment of the Pesticide Technical Advisory Committee(PTAC) to the FPA. When the “Dirty Dozen” Campaign was launched internationally by non-government organizations led by the Pesticide Action Network International, risk assessment became the basis for the banning of most “Dirty Dozen” pesticides in the Philippines although it was probably more to the credit of a determined senior medical toxicologist-pediatrician in the technical committee that the risk assessment process successfully led to the banning of the said pesticides.

Sometime in 1990, endosulfan was noticed to have become the most frequent cause of death among pesticide related poisoning cases reported to National Poison Control Center established by the lone medical expert sitting at the PTAC. A review of endosulfan was undertaken by the toxicology subcommittee of PTAC using the same risk assessment principle used in evaluating the “Diry Dozen” pesticides. As a result, the FPA ordered a ban on endosulfan 35%, allowing only 5% formulation and severely restricted its use. Immediately, Hoechst, the major manufacturer of endosulfan, took the FPA to court and was able to obtain an injunction(on procedural grounds) that allowed it to continue selling endosulfan 35%. In April 1993, Hoechst slapped a lawsuit of more than US800,000 on a medical pharmacologist-toxicologist for reportedly stating in a conference that “Thiodan(trade name of endosulfan) causes cancer” as quoted in three major newspapers. The feature service and the journalist who wrote the story were also sued. At the same time, Hoechst also sought out and confronted the female farmer who testified in the conference about the harmful effects of a Hoechst pesticide product. The confrontation has left the farmer frightened. In September 1993, the FPA issued a new order reiterating the ban and restriction on endosulfan , together with four other highly toxic pesticides. Again Hoechst vigorously contested the order through a restraining order from a judge who was later exposed to have close relations with the company’s lawyer. The company exerted every effort to negate the ban order, including seeking the intervention of the President warning of serious and undesirable consequences on the government policy of attracting foreign investors and instructing its dealers not to cooperate with the FPA in its effort to obtain a market inventory of the endosulfan products. In January, 1994, the Philippine Supreme Court ordered the suspension of the proceedings at the Regional Trial Court effectively lifting the restraining order against the ban on endosulfan. Hoechst continued to advertise Thiodan without mentioning restrictions on the use of the pesticide and without warning of adverse effects. The FPA found the ad to be “false, misleading and deceptive” and ordered the company to stop the ad. Subsequently, the ban took effect on June, 1994.

An exemption on the ban of endosulfan 35%, however, was granted on a temporary basis by the FPA for use in pineapples under supposedly strict monitoring guidelines. Recent information reveal that these guidelines were wantonly violated with impunity and extension of temporary use has been granted without reasonable justification. It was also observed that although the use of endosulfan has dramatically been reduced, continued use has been reported and documented in various parts of the country, particularly in Mindanao. The explanation was that endosulfan was probably coming in from the “backdoor” but there is suspicion from knowledgeable sources that the supply was probably coming also from the excess inventory of stocks at the time of the effectivity of the ban. The post-ban inventory has never been accounted for properly.

B. Health Risks

Despite clear evidence that endosulfan was presenting significant risks to human health and safety, especially under conditions of use in Third World countries, Hoechst has been claiming that “Consumer safety (was) proven” and that endosulfan was “relatively safe, effective, user, beneficial insect and environment friendly pesticide”(PDI, 1993). However, several studies and review documents from different sources consistently show that endosulfan is highly poisonous and easily causes death and severe acute and chronic toxicity to various organ systems, including mental impairment, neurologic disturbances, immunotoxicity, reproductive toxicity, maternal and developmental toxicity, liver and kidney damage, cardiac disorder, blood disorder, respiratory depression, skin irritation, and many others(ATSDR,1993; Micromedex, 1993). In addition, endosulfan has also been reported to be an endocrine disruptor(Soto, 1993; JOF, 1998). In the Philippines, endosulfan accounted for the largest number of deaths due to pesticide poisonings reported to the National Poisons Control and Information Center in 1991(NPCIS, 1991) and continued to be one of the highest causes of pesticide poisonings until the time of banning. The company makes much use of the document “Endosulfan 91-115 JMPR 1989”(WHO, 1989) published by the WHO claiming that the document “clearly and categorically stated that endosulfan has no indication whatsoever for causing cancer”(PDI, 1993). This claim, however, is not supported by an actual review of the available data. The carcinogenicity studies reviewed were in fact limited by inadequate reporting and survival and, therefore, no valid conclusion of “no-effect” can be derived from them(IPCS, 1988). Looking at the raw data of the carcinogenicity studies submitted by the company, there is in fact valid reason to suggest that endosulfan is carcinogenic. For example, one study showed a high incidence of lymphosarcoma in both the control and endosulfan treated group(IBT, 1965). Although there was no statistical difference found between the two groups, the high incidence of lymphosarcoma by itself gives a warning that endosulfan possibly causes cancer of the lymphatic system and that the similarly high incidence of the disease in the control is highly unusual and could have been the result of a methodological error resulting in undue exposure also of the control group to the carcinogenic agent. Furthermore, there are other studies which show that endosulfan can cause cancer. For example, one study (Reuber, 1981) showed that endosulfan was carcinogenic in male and female rats at all sites examined. It also induced liver tumours in female mice. Another study(Fransson-Steen, 1992) found that endosulfan promoted the growth of altered hepatic foci in rats in a similar manner as the structurally related chlorinated insecticides, chlordane, aldrin and heptachlor did, indicating that endosulfan is a potential liver tumour promoter .

The company also claims that endosulfan is non-mutagenic and non-genotoxic based on the negative findings indicated by the company sponsored studies. The WHO document in 1989 also echoed this negative findings which became the basis of subsequent erroneous characterization in various publications that endosulfan was non-genotoxic. However, several independent studies have shown that endosulfan is genotoxic. Data from in vitro and in vivo mutagenicity studies generally provide evidence that endosulfan is mutagenic, clastogenic and induces effects on cell cycle kinetics. For example, endosulfan was found to be mutagenic in various assay systems including the Ames test, micronucleus test, and yeast gene conversion test(Syliangco, 1978; Adams, 1978; Yadav et al., 1982). Endosulfan was also found to cause chromosomal aberrations in hamster and mouse, sex-linked recessive mutations in Drosophilia, and dominant lethal mutations in mice(Velasquez et al., 1984; Naqvi and Vaishnair, 1993). Studies in human cells both in vitro and in vivo also showed that endosulfan caused the occurrence of sister chromatid exchanges indicating chromosomal damage(Sobti et al., 1983; Dulout et al., 1985). Very recently, a team of researchers in Japan found further evidence of endosulfan genotoxicity using sister chromatid exchanges, micronuclei, and DNA strand breaks as detected by single cell gel electrophoresis as biomarkers(Yuquan Lu et al., 2000).

Another issue which has not been given due attention is the inappropriate hazard classification of endosulfan by the WHO. The WHO has classified endosulfan as a Class II or “Moderately Hazardous” pesticide based mainly on the LD50 value taken from company generated acute toxicity data. However, a closer examination of available data, including data from independent sources, clearly show that endosulfan should belong to at least Class Ib or “Highly Hazardous” category since most of the LD50 values fall within the Clas Ib category range and other acute toxicity data(Micromedex, 1993) clearly indicate that endosulfan’s acute toxicity profile is comparable or even worse than the toxicity profile of other pesticides belonging to Class Ib category. In fact, the European Union has classified endosulfan as a Class Ib (IPCS, 1988) pesticide in its labeling requirements and the US EPA has also classified endosulfan as highly toxic and has listed endosulfan on the Extremely Hazardous Substances List under the Environmental Standards(US EPA, 1990). Using the criteria(WHO, 1988) recommended by the WHO itself in classifying pesticides, endosulfan should have been classified as Class Ib. It appears that the WHO technical committee gave more weight to company generated data and apparently ignored independent data.
It is worth noting that the studies reviewed in the document “Endosulfan 91-115 JMPR 1989” often cited by Hoechst as its basis for claiming the innocuousness of endosulfan were the submissions of the company itself and there was hardly any independent study included in the review. In addtion, many of the studies commissioned by Hoechst were found (1983) to have been performed by the Industrial Biotest (IBT) of Chicago which was convicted for fraudulent practices, including fabrication of data which became partly or wholly the basis of approval of endosulfan in many countries. As late as the early 1990’s, Hoechst was still submitting data obtained from IBT to the Philippine pesticide regulatory agency when the company was required to submit scientific data for the purpose of risk assessment review by the Pesticide Technical Advisory Committee.

C. Environmental risks

Endosulfan is considered as extremely toxic to aquatic life, particularly, fish. Endosulfan can cause fish kills even when used at recommended application rates. In August, 1995, run-off from cotton fields contaminated with endosulfan resulted in the death of more than 240,000 fish along a 25 Km stretch of a river in the State of Alabama, USA. Investigations showed that the pesticide had been sprayed according to label instructions. In the Sudan, in 1988, barrels washed in irrigation canals caused fish death. Three people died after drinking water from the canal. (Dinham,1993).

Bioaccumulation of endosulfan and the metabolite endosulfan sulfate is significant in aquatic species. Combined residues had been found to have concentrated after 96 hours from 81-245X to as much as 1000-1344X in grass shrimp, pinfish, spot, and striped mullet. After 28 days, the combined residues had concentrated 2249X in edible tissues and 2755X in whole fish.Endosulfan also accumulated 600X in the Pelecypod, Mytilus edulis after 50 hours. There was also slight concentration in two species of mussels exposed to the chemical for 36 days.(Schimmel et al., 1977; Reish et al., 1979; Roberts, 1975).

In a report by the IPCS, endosulfan was considered of moderate to low toxicity to honey bees and was only moderately toxic to birds, particularly for mallard ducks and ringnecked pheasants(IPCS, 1984). However, the National Wildlife Federation (US) states that endosulfan is extremely toxic to wildlife and acutely toxic to bees. It also warns that birds feeding in treated areas could be killed (NWF, 1987). The Danish government also classified endosulfan as acutely toxic to birds with LD50 of 28-42 mg/kg. (Hansen, 1993).

Some toxic effects of endosulfan to plants have also been reported. It was found that endosulfan changed the permeability of root membranes resulting in coiling of the root radical, inhibition of root growth, stunting of shoots, and burning of the tips and margin of leaves.(IPCS, 1984). Endosulfan has also been found to be toxic to a wide variety of microorganisms. Some reports have indicated that endosulfan affects the membrane components of the yeast Rhodotorula. Endosulfan was found also to reduce the productivity in a natural phytoplankton community by 86.6% during a four hour exposure and has been reported as one of the most toxic organochlorines to soil algae, actinomycetes and bacterial colonies(IPCS, 1984).

Endosulfan is also highly persistent in soil. In one study, it was found that the half-life of alpha endosulfan was about 60 days and that of beta endosulfan was about 800 days after incorporation of technical endosulfan into soil at 6.7 kg/ha.(Stewart, 1974). In another study, when 0.38 ppm of endosulfan was applied to Colorado soil, it was found that 0.04 ppm remained after three years(Rao, 1980). Other studies done under varying soil conditions showed persistence profiles ranging from 42 days to 100 days with percentage recoveries ranging from 17 to 54% for alpha endosulfan and 65 to 91 % for beta endosulfan.(El Beit et al., 1981). It must be noted that the persistence of toxicity is actually longer since the major degradation product, endosulfan sulfate is as toxic as the parent compound (ATSDR,1993).

When released to water, alpha endosulfan was found to have a degradation half-life of 35.4 to 150.6 days and beta endosulfan, 37.5 to 187.3 days at pH 7 and pH 5.5 respectively(Greve, 1971). Endosulfan has been found in surface water outside the spraying season. A survey of 11 agricultural watersheds located in Southern Ontario revealed that endosulfan, together with atrazine and simazine, persisted long enough to appear in water throughout the year. In 14% of water samples, endosulfan levels exceeded the water quality criteria established by the International Joint Commission For the Great Lakes(Frank et al., 1982). Endosulfan also persisted in ground water at deep soil layers in concentrations ranging from 0.009 – 0.053 ug/L up to 20 days after last spraying (Paningbatan et al., 1993). The potential for endosulfan to contaminate ground water was also demonstrated by a study on pesticide residues in selected well waters in major rice producing areas in the Philippines wherein endosulfan residue levels ranged from 0.002 to 0.03 ug/L (Medina et al., 1991).

Volatilization of endosulfan is expected to be significant.. In ambient air samples from 14 states(US) taken from 1970 and 16 states in 1971-72, endosulfan was detected in 2.11% of the samples with a mean concentration of 111.9 ng/cubic meter (with a maximum of 2256.6 ng/cu m) for alpha endosulfan(Kutz, 1976). Endosulfan can be transported over long distances in air. Samples of precipitation collected in the Great Lakes ecosystem contained endosulfan concentrations of 1-12 parts per trillion(Eisenreich, 1981). The concentration of of alpha endosulfan in precipitation from Canada ranged from 0.001-0.116 ppb and that of beta endosulfan from 0.001-0.031 ppb (Brooksbank, 1983). Concentrations of endosulfan in rain/snow samples collected in rural and urban areas were 1-10 ppt (Miller, 1981).

Food contamination with endosulfan is widespread. Several endosulfan residue surveys in various types of food consistently reveal significant contamination with endosulfan. For example, monitoring of pesticide residue levels in food from July 1, 1969 to June 30, 1970 done by the US FDA show that 17 of 240 food composites contained endosulfan concentrations ranging from 0.001-0.006 ppm.(Dugan, 1983). In another study, one of infant food composites contained 0.002 ppm beta endosulfan and 0.004 ppm alpha endosulfan. Two of 110 toddler food composites contained from 0.001-0.004 ppm beta endosulfan.(Podrebarac, 1984). In the Philippines, a survey of agricultural crops including various vegetables and fruits also revealed significant contamination with endosulfan at concentrations ranging from 0.01 to 0.11 parts per million (BPI, 1995).

Step 2. Identifying what is known and what is not known

A. Uncertainties in human toxicology

The physicochemical characteristics and most of the intrinsic toxicological properties of endosulfan, especially its acute toxicity, are fairly well known and have been characterized by a large amount of scientific information. It is the chronic and the “low level” toxicity that is mostly saddled with uncertainties, especially, as far as definitive cause and effect relationships are concerned. For example, the issue whether endosulfan causes cancer in humans is still considered not sufficiently backed-up by scientific evidence. There is still no adequate evidence, as what has been demonstrated, for example for such chemicals as lindane, captan or dichlorvos, to classify endosulfan as carcinogenic to humans, as far as most regulatory agencies are concerned. However, as indicated in the discussions above, there are a number of scientific studies that provide reasonable grounds to implicate endosulfan as a carcinogenic substance, albeit, not to the same degree of certainty as other previously identified carcinogenic substances. Given the extreme difficulty(prospective studies cannot be done because of obvious ethical reasons) of conducting human studies to demonstrate clearly the carcinogenicity of substances like endosulfan, it would be unrealistic to defer judgement on what steps should be taken to address the issue due to this uncertainty. The application of the precautionary principle would demand that precautionary action, like applying the Delaney Clause, should be undertaken.

Similarly, “low level toxicity” is still not reflected in most regulatory standards for endosulfan as far as “tolerance levels” or “acceptable limits” are concerned. It must be pointed out that these standards are based mainly on acute toxicity data generated in routine laboratory screening tests for acute toxicity or at best, from limited data on acutely observable toxicity associated with biological levels(usually blood or urine levels) in humans. These standards, therefore, would not be relevant to insidious and largely asymptomatic chronic toxicity that usually manifests only after significant cumulative damage have been inflicted, which, at that stage, the association between exposure and damage would be extremely difficult to demonstrate. Recently, however, there had been a flurry of scientific research indicating very strongly that “low level toxicity” (at extremely low levels, ex. one tenth of a part per trillion, not previously measurable due to limits of technology), especially in the form of “endocrine disruption”, indeed occur for a large variety of synthetic chemicals, especially organochlorines like endosulfan. This endocrine disrupting effects apparently occur at a very critical period of fetal development such that extremely minute levels of exposure at a very short period of time would be enough to cause permanent neurological, reproductive, immunologic and other effects. These effects, while almost imperceptible to the acutely exposed adult generation, have devastating implications on the survival of succeeding generations. While this have been observed only so far in some animal species, such as the beluga whale, bald eagle and the alligator, there is no reason to believe that the same effects would not occur in humans.
Uncertainties in the contribution of exposure to toxic chemicals to the increase of various kinds of diseases such as Parkinson’s disease, diabetes, autoimmune diseases, hypersensitivity diseases, Alzheimer’s disease, autism, new emerging infectious diseases, and many others have been largely unexplored by scientific researches. Yet, current scientific knowledge would tell us that there are a variety of plausible mechanisms by which toxic chemicals can cause these various kinds of diseases exhibiting increase in incidences.

The likely additive or synergistic (greater than additive) effects that might occur due to multiple exposure to a variety of toxic contaminants in the environment is also one of the uncertainties which have been largely ignored by existing regulatory standards mainly because of lack of scientific data demonstrating cause and effect relationships. Yet, given the existing scientific knowledge on mechanisms of toxicity, and given the thousands of toxic environmental contaminants that populations are already exposed to, it should be expected that these additive or synergistic toxic effects already occur.

B. Uncertainties in ecotoxicology

Most of what is known about the ecotoxicology of endosulfan have been generated in developed countries, particularly, in the US. Due to the general lack of technological and economic capabilities to generate scientific data, developing countries, including the Philippines, have not been able to gather sufficient local data to serve as basis for assessment of potential threats of pollutants in the environment. Nevertheless, while there are likely to be some qualitative and quantitative differences in the toxicologic effects of these contaminants depending on local environmental characteristics, the basic toxicologic profile of these contaminants are not likely to be too different. For example, there is no reason to believe that the extremely toxic property of endosulfan on fish would be substantially different when local species of fish is concerned. While information on the effects of endosulfan on local fish species are mostly anecdotal, it would be illogical to say that endosulfan does not affect our local fish species because there has not been any scientific study demonstrating endosulfan toxicity on local fish species. Another apparent uncertainty would be the chronic effects of wildlife, including the endocrine disrupting effects. It is in this area that even anecdotal information would be extremely difficult to find. Yet, again, there is no reason to believe that what has been observed scientifically in developed countries regarding the reproductive and developmental effects that had been leading to slow extinction of wildlife species is not likely to occur here in the Philippines because of differences in wildlife species. The mechanisms identified leading to the adverse effects are certainly applicable to the different wildlife species we find here in our country.

C. Uncertainties in the level of exposure

In general, there is also very little data on exposure levels of different environmental and biological media to endosulfan. Again this reflects the underdeveloped technological and economic capability of the Philippines in addressing environmental problems through scientific research and documentation. Nevertheless, some amount of data are available(although some data are yet to be accessed) to assess the environmental load and the likely exposure levels of humans and animal species in the Philippines to endosulfan. For example, an estimate of endosulfan run-off to Manila Bay can be calculated if the total amount of pesticide consumption in the surrounding provinces will be obtained. Applying general principles in environmental distribution and fate of chemicals according to their physicochemical characteristics, potential exposure can be estimated using certain compartmental analysis models. This kind of modeling has in fact been applied in the pesticide risk assessment that had been done previously for the Batangas Bay region.
There are also some data available, although limited, on actual residue levels obtained in food items and water media as mentioned in the previous discussions in Step 1 of this document. This would allow us to directly assess the potential body burden in exposed populations and thus estimate the likelihood of harm. For example, local data show that measured endosulfan levels in groundwater in certain areas range from .002 to .053 ug/L. Data on pesticide residue monitoring on certain food items also reveal the presence of endosulfan from .01 to .11 ppm . Using this limited amount of local data, one could determine the approximate body burden that exposed populations are likely to carry. An estimate of the likelihood of harm can then be made using certain standards of exposure levels likely to cause harm. It must be pointed out again, however, that existing standards are largely inadequate since these are based mainly on limited acute toxicity models largely derived from animal studies. A precautionary approach would be to consider low levels associated with insidious effects such as endocrine disrupting effects.

Step 3. Reframing the problem

From the foregoing discussions, it is evident that endosulfan has been a major source of health and environmental problems and continue to be so unless immediate and long-lasting remedial measures are instituted. The reason for its being introduced into the environment need to be re-examined. Is there really a need for endosulfan? What human need does endosulfan fulfill? If indeed there is a need, are there no better ways to fulfill the need? These questions were hardly ever asked since endosulfan and other synthetic chemicals started to proliferate after the second world war. The intensification of industrial agriculture in the 1960’s further led to the casual acceptance of the necessity of pesticides, including endosulfan, in agricultural production. Potential problems with the inroduction of synthetic chemicals into a fragile ecosystem which required eons to develop intricate biological adjustments and inter-relationships were not recognized. The problems of pest infestations and resulting loss in production were emphasized and increased yield was automatically associated with pesticide use. Yet, data from various sources show that improved agricultural production need not be dependent of pesticide use. On the contrary, the experiences in many communities in India, Indonesia and several others, have shown that pesticide use lead to certain crop failures and over time, total yield actually decrease while health and environmental problems associated with pesticide use increase. Several countries, in fact, realizing the health and environmental consequences associated with endosulfan, have either totally banned or at least restricted severely the use of endosulfan.
Certain risks, perhaps, may be acceptable if there is an important need that a certain chemical fulfills and no other alternatives offer a better way of fulfilling that need. In the case of endosulfan, the need is supposedly to prevent loss of agricultural production by controlling pest infestation. Examining this need, however, shows that fulfilling this need cannot justify the resulting health and environmental damage already known and the further potential threats that are likely to occur. Food is an essential need but food can be produced without the need to use toxic synthetic chemicals. History shows that communities all over the world have always been able to produce food for their growing population on a self reliant manner using sustainable methods of agricultural production. The problem of food scarcity for many is not the result of underproduction of food but due to extremely skewed distribution of wealth and control of resources. The wide gap between the few extremely rich and the many who are extremely poor is the main problem. Industrial agriculture, which brought about the use of pesticides and other synthetic chemicals into the picture of food production, has aggravated the situation. Furthermore, the emphasis on cash crops and other non-essential agricultural products by the prevailing world economic system has led to the relative scarcity of land and other resources devoted to the production of essential food.

Step 4. Assessing the alternatives

There are several alternatives to the purported uses of endosulfan.

One is the use of integrated pest management(IPM) methods. For a major food crop like rice, several country experiences have already demonstrated that improved crop production even with the use of high yielding varieties is achievable without the use of endosulfan and with minimal use of other synthetic pesticides. Indonesia, for example, the Community IPM Program assisted by the Food and Agricultural Organization (FAO) and implemented mainly by farmers through the farmer field schools have resulted in significant increase in yields and income as their pesticide and fertilizer costs have gone down. The Indonesian government has also banned more than 50 pesticides, including endosulfan, from being used in rice paddies. The FAO’s Community IPM Programme now operates in 12 countries in South and Southeast Asia.
Another is the use of sustainable agriculture systems, including biodynamic farming and other forms of organic agriculture which completely shuns the use of any synthetic pesticide or fertilizer. These systems usually involve the conservation and development of indigenous varieties for better pest resistance and improved yield and other crop characteristics. Sustainable agriculture systems have been successfully demonstrated by several non-governmental organizations and the success of this alternative is reflected by the tremendous increase in the demand and sales of organically certified agricultural products throughout the world. Various local farmers’ organizations have developed their own sustainable agriculture systems which have shown relative success despite overwhelming lack of resources and support from official bodies and despite the aggressive promotional activities of the agrochemical companies. MASIPAG (Farmers Scientists Partnership for Agricultural Development), for example has now successfully demonstrated that through the empowerment of farmers, pesticides and synthetic fertilizers are not necessary to achieve increased and sustainable agricultural production.

A specific natural alternative to synthetic chemical pesticide is the use of botanical pest control agents, such as neem and other plant preparations either in crude form or as extracts. Success in using these botanical pesticides, however, is usually associated with a more comprehensive and integrated approach to pest control. Another would be the use of biological pest control agents such as Bacillus Thuringiensis, Diadegma, Trichogramma and others. Cuba, for example, has demonstrated the success of using biological pest control agents in their agricultural crops except for tobacco and sugar. It must be noted that despite the desirability of replacing synthetic pesticides with naturally derived pest control agents, there are also attendant risks involved in using natural alternatives, although much less problematic than the synthetic ones.
One might ask, however, why despite several successfully demonstrated alternatives which are obviously more health and environment friendly than endosulfan have not attained the centerpiece in agricultural production in the world. It is obvious that the major factor in determining the system of agricultural production is not technology but social relations. The prevailing social relations and power structures (political, economic, and cultural) do not favor the adoption of environmentally friendly systems of agricultural production. The power and dominance of a few powerful agrochemical corporations and their allies impose the chemically intensive and environmentally destructive systems of agricultural production.

Step 5. Determining the course of action

Ideally, the course of action should be determined collectively with the active participation of public interest groups. While the government has the primary responsibility in formulating and implementing the appropriate courses of action pertaining to the problem at hand, the entire process leading to legislation, policies, and implementation should be transparent with the different stakeholders involved. It must be clear, however, that the subject of regulation, the company whose product is under scrutiny, should not be involved in decision making but only in the consultation process for the purpose of information and clarification The sequence of events that led to the severe restriction of the use of endosulfan by the Philippine government in 1993, although significantly influenced by the active lobbying of public interest groups and the tenacity of some concerned academics, was far from transparent and participatory. The government instrumentalities involved were not coherently acting together and the chemical company whose product was the subject of regulation was arrogantly defiant of government authority. Clearly, the arrogance exhibited by the chemical company stemmed from the fact that the chemical industry, in general, have traditionally been successful in having their way in a developing country as far as government regulations of pesticides are concerned.

Having now a clearer picture of the threats, hazard and exposure characteristics, uncertainties, need and alternatives, and using the precautionary approach in evaluating the weight of evidence, certain basic recommendations can be forwarded pertaining to endosulfan. For example:

1. A complete ban on the importation, distribution and use of all formulations of endosulfan should be instituted immediately. Special attention should be given to implementing the “stop use” directive in all the provinces with river tributaries emptying into the Manila Bay area and in the areas adjacent to Laguna Lake.

2. A vigorous public education campaign should be conducted by the government with the cooperation of all stakeholders to stop the artificially created demands for the product and to prevent illegal use.

3. Measures should be instituted by government and non-government institutions and organizations to support sustainable agriculture, integrated pest management programs and similar initiatives and to create incentives for consumer support for organically produced agricultural products.

4. The government should support international initiatives to phase out and eliminate highly toxic, persistent and bioaccumulative pollutants, particularly by ratifying as soon as possible the Stockholm Convention on Persistent Organic Pollutants.

5. The government should pursue its earlier initiative (IFCS Manila Meeting of 1996) to have endosulfan included among the list of persistent organic pollutants that warrant international action under the Stockholm Convention.

6. Measures should be undertaken to monitor residue levels in food, water, and other relevant environmental media to determine the effectiveness of control and remediation measures and to evaluate the progress in reducing the environmental load of the pesticide.

7. Biological sample and health monitoring should also be undertaken whenever feasible to evaluate chronic health effects of the pesticide.

Step 6. Monitoring and follow-up

Recommended courses of action should be followed-up until measures are actually carried out. The assessment team and the supporting institution should be primarily responsible in seeing to it that the recommendations are acted upon by the appropriate bodies. Progress in carrying out the specific measures of remediation should be monitored closely. The output of the assessment team should not be allowed to remain stacked away in library shelves. Similary, after the recommended actions are translated into concrete government legislation, policies or executive/departmental orders, monitoring of the implementation of the specific provisions of those policy directives should be undertaken by the institution/s or government agency or agencies responsible for making those recommendations in the first place.


An objective and careful review of the existing data on endosulfan clearly demonstrates that endosulfan belongs to the group of highly toxic Persistent Organic Pollutants (POPs). Endosulfan was in fact in the initial list of POPs being considered for worldwide elimination at the first meeting of experts in Vancouver, Canada in 1994, jointly convened by the governments of Canada and the Philippines as a response to the growing worldwide concerns about the serious damage to health and the environment that persistent organic pollutants are causing. In the subsequent Manila meeting in 1996, the Philippine delegation strongly recommended the inclusion of endosulfan, together with triphenyltin compounds, in the initial list of POPs that would be subject to worldwide phase-out and elimination through a legally binding international agreement or treaty. This position gained support from many country delegations, including public-interest groups, but was vigorously opposed by the chemical industry representatives, particularly, Hoechst. Eventually, endosulfan disappeared from the initial list of POPs. For some reason, the Philippine government suddenly lost interest in pursuing its position on endosulfan and no longer sent its scientists earlier involved in the POPs issue to subsequent POPs meetings. From an initial list of about 40 POPs, the list was trimmed down to only 12, namely, Aldrin, Chlordane, Dieldrin, Endrin, DDT, Heptachlor, Hexachlorobenzene, Mirex, Toxaphene, PCBs, Dioxins and Furans. The POPs treaty negotiations was then set into motion without endosulfan among the initial POPs targetted for elimination. It is significant to note that all the initial POPs which are not by-products have already been banned or severely restricted in most countries and not one is still being manufactured by any major chemical company based in developed countries. No major chemical company from the developed countries, therefore, stands to lose profits from a worldwide ban on these chemicals.

This is an indication that the intense lobbying of the chemical industry in the initial meetings on the POPs issue was very successful. It was the feeling of the Philippine experts involved in the POPs issue that the active intervention of the chemical industry representatives during the POPs meetings have somehow influenced the decision to exclude endosulfan from the initial list of POPs. This was made more evident by the fact that a representative of Hoechst at one point attempted to alter the background document on endosulfan not through open discussion and debate but through direct access to some key people involved in organizing the experts meetings on POPs.


The foregoing account brings to the forefront the question of who really decides on the matter of risk assessment of toxic chemicals such as pesticides and POPs. While it is commonly accepted that health and safety of the people and the environment should be paramount, the reality is that corporate interests and profits are the dominant considerations influencing decisions pertaining to the production, marketing and use of toxic chemicals. “Science-based” risk assessment is not the decisive factor in determining the regulatory status of toxic chemicals. The reality of “power relations” between the strong and the weak, between the rich and the poor and between the First World and the Third World are very much in the decision making processes of governments in their attempts to confront the problems related to toxic chemicals.

Corporations often defend their products despite overwhelming evidence of harm to human health and the environment by referring to the extensive testing their products undergo, to the approval of regulatory bodies in many countries based on “risk assessment”, and to the tacit approval by the international bodies such as WHO and FAO. However, past experiences clearly show that profit-driven corporations exert all efforts to ensure profitability by attempting to exercise control, through their vast financial resources and political clout, over all factors that may influence the market, including: information and research, scientists and academic institutions, regulatory bodies and governments, judges and politicians, international organizations, and even non-governmental organizations.

This reality makes science and corporations inherently contradictory. Science is about truth and true science means the search for new knowledge in a systematic and logical manner so that people may benefit from it. Science involves astute observation of objects and events, careful formulation of hypotheses, unbiased experimentation and analysis, and logical conclusions. On the other hand, corporate pseudo-science is characterized by manipulation of objects and events, vested interest driven and obscured formulation of hypotheses, biased experimentation and analysis, and market directed, pre-determined conclusions. Data are collected, generated or even fabricated to support corporate objectives and achieve marketing targets. Arguments are not based on human logic but are pre-determined by corporate interests. Information is not something that may be true or false but something that is created and packaged to sell a product. Any information that tends to diminish the sales of a product is immediately considered a disparagement (even illegal) and therefore, must be suppressed. The corporation would demand “scientific proof” and puts the burden on the victims and complainants. At best, when denial is no longer possible, the corporation would concede that the information “needs further study” and still would resist complete banning of their toxic product.

Very recently, the idea of using the precautionary principle in dealing with toxic chemicals has been pushed strongly by many sectors, especially, independent scientists and public interest groups. Essentially, the precautionary approach attempts to avoid the creation of pollutants in the first place, in contrast to risk assessment strategies that attempt to manage pollutants to some level of “acceptability” after they have been created. With the precautionary principle, there is recognition that long-term impacts of toxic chemicals are difficult to predict and often impossible to prove. It also accepts the fact that, historically, many toxic chemicals have been shown to cause serious and often irreversible damage to human health and the environment. While the precautionary approach must still rely on science and on certain elements of the “risk assessment” methodology to identify potential risks to human health and the environment, it is not dependent, as traditional risk assessment is, on a system of decision making that demands generation of extensive scientific data and requires exhaustive analysis of risks as pre-conditions to policy formulation and action. This is particularly relevant to Third World countries where the resources needed to characterize the risks are not readily available. Pollution prevention is the only logical option.

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©heal toxics, 2003
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