For the Prohibition of Paraquat in Costa Rica

I. Introduction

In the last 50, Costa Rica has experienced major changes in agricultural production. The massive introduction of agrochemicals, as part of the Green Revolution, has caused amongst other things, environmental contamination, observable in both impacts to natural resources and the health of agricultural workers and farmers.

The lives of rural families have been greatly impacted by modern production practices. Policies that prioritize export production over national production have resulted in the degradation of productive land, the contamination of watersheds, and the loss of forest cover. This type of production is characterized by intensive and extensive monoculture systems and the indiscriminate use of agrochemicals.

The use of the herbicide, PARAQUAT, an agrochemical responsible for the majority of pesticide related poisonings reported in Costa Rica, is used by transnational companies cultivating bananas, pineapples, and citrus, and by small, medium, and large-scale national producers of coffee, sugar cane, ornamental plants, and other crops.

Stories like that of Maria R, who used PARAQUAT as a way to end her life of poverty and exploitation, are more common than we would like to think. PARAQUAT, a preferred substance for committing suicide, causes severe health effects. Its ingestion damages to internal organs (gastrointestinal tract, lungs, kidneys, liver, heart). Additionally, PARAQUAT intoxication causes, bleeding from the nose and falling out of fingernails. Fibrosis of the lungs is the usual cause of death from PARAQUAT poisoning.

The Foro Emaús network has been working for the past ten years for a system of banana production that respects social and environmental justice. After analyzing the severity of the effects caused by the use of PARAQUAT, together with numerous organizations of farmers, environmental groups, and unions, we are developing this campaign for the prohibition, through an executive decree, of the use and registration of PARAQUAT in Costa Rica.

We are convinced that if we achieve a reduction in the use of agrochemicals,in this case PARAQUAT, we are promoting a healthy system of agriculture and contributing to the creation of a better tomorrow, where community health, social justice, and a respectful relationship with Nature, will be the pillars for the development of our communities.

According toe the “CODE OF CONDUCT FOR THE USE AND DISTRIBUTION OF PESTICIDES” of the ORGANIZATION OF THE UNITED NATION FOR FOOD AND AGRICULTURE (FAO) “ we should renounce those pesticides that are not guaranteed to be safe for use”. We believe that this is the case of PARAQUAT.

II. Paraquat: General Information

A. Introduction

(partially taken from “Unintentional fatal Paraquat poisonings among agricultural workers in Costa Rica” Wesseling et al. 1997)

The use of pesticides is the cause of thousands of intoxications worldwide, especially in the so called third world (OMS; 1990).

During the last several years, there has been an advancement in the control of marketing and use of agrochemicals. Without a doubt, this control has relulted in a relative reduction in the negative impacts these products have on the environment and health. However, despite these efforts, the number of pesticide intoxications in Costa Rica continues to increase (1).

In this document we will analyze the case of the herbicide Paraquat, also known as “Gramoxone”, widely used in Costa Rica and an additional 130 countries of the world (2).

This product is toxic to humans, causing severe damage to lungs, kidneys, and the liver. Deaths resulting from Paraquat intoxication are usually due to irreversible lesions on the lungs. There is no known antidote nor effective treatment to reverse Paraquat poisonings (Vale and Volans, 1987). No one knows exactly how many deaths have been caused by this product since in first became available on the market in 1962, but it is estimated that it is several thousand (Onyon and Volans, 1987; IPCS, 1984).

Those that defend the use of Paraquat argue that the danger is limited to intentional ingestion of the product (suicide). According to the company Zeneca, manufacturer of this product, with the 1987 addition of a blue colorant, an odor, and another substance that produces vomiting, the possibility of accidental poisoning through oral ingestion was eliminated (Zeneca Chemicals, 1993).

In general, it is still not believed that occupational exposure to this product poses a real risk (Onyon and Volans, 1987, Hart, 1987; Garnier, 1995). In various studies, exposure has been quantified through dermal exposure and residues in the urine of workers. Comparison of these results with the levels toxic to animals, these studies conclude that prescribed concentrations are not dangerous in temperate zones (Swan, 1969; Staiff et al., 1975; Howard, 1980; Chester and Wooleen, 1981; Chester et al., 1993; Senanayake et al., 1993). However, there have been frequent reports of deaths of workers intoxicated through oral and dermal exposure to Paraquat, as well as non fatal worker intoxications. (Stevens and Summer, 1991; Wohlfart, 1982; Levin et al, 1979; Athaneselis et al., 1983; Fitzgerald et al 1978; Garnier et al, 1994; Wesseling et al., 1993; Weinbaum et al., 1995).

In Costa Rica, Paraquat is the principle cause of worker intoxications from pesticides (Health Ministry, Report on occupational and environmental aspects of banana production, 1948, p.48).

B. Physical and Chemical Characteristics

Paraquat is a synthetic chemical substance used as an herbicide. Its commercial name is “Gramoxone” but, is also marketed under different labels including: Radex, Crisquat, Dextrone, Dexuron, Extra, Herbaxone, Orthoweed, Spot Killer, and Sweep (3). This product is manufactured by the company Zeneca. It is one of the most used (not the most used) herbicides in Costa Rica.

When applied in fields, Paraquat is rapidly absorbed by soil particles, especially clays. Remaining residues in the soil cannot be absorbed by plants, earthworms, nor microorganisms. Due to this characteristic, Paraquat has a long half life in soil: from 16 months (in laboratory studies under aerobic conditions) to 13 years (field studies) (5). In Costa Rica, Paraquat residues have been detected in soils of coffee farms where it has not been applied for three years.

In water, Paraquat residues can be absorbed by mud or aquatic plants. Laboratory studies show the half life of Paraquat in water varies from 13.1 hours to 23 weeks (8).

In general, ultraviolet rays and solar light decompose Paraquat into less toxic products. However, because this herbicide is rapidly absorbed by the soil, bonded molecules resist photo-decomposition. It is in this manner that there is no observed degradation of Paraquat in sandy soils after 2 years of exposure to natural light.

C. Toxicity

Paraquat is on the “Dirty Dozen” list of the 12 most dangerous pesticides that should be prohibited according the international organization Pesticide Action Network (PAN). This herbicide is already prohibited in various countries including Austria, Bulgaria, Denmark, Finland, Switzerland, Argentina, and the Dominican Republic. It is restricted for use (professional authorization is needed to purchase it and it can only be applied by a certified operator) in the United States and Germany (3).

In Cost Rica, in 1999, the national media published numerous articles (9), in which Herman Weinstok from the Health Ministry affirmed that the use of Paraquat should be restricted or, at least, have its level of toxicity changed from “moderately toxic” to “highly toxic”. Paraquat continues, until this day, to be freely sold under the label “moderately toxic”.

D. Health Effects

Paraquat is completely toxic to human beings. Many cases of acute intoxications and deaths have been reported (10).

1) Acute Toxicity

In human beings, the ingestion of 35mg per kilo of body weight is lethal (11), or, in other words, a person that weighs 65 kg (162.5 lbs) would die after ingesting 2.2 grams of Paraquat. When Paraquat is ingested in lower doses it causes burns to the mouth and throat, followed by a severe irritation of the gastrointestinal tract, which provokes abdominal pain, nausea, vomiting and diarrhea. Other symptoms include thirst, difficulty in breathing, and accelerated heart rate. Other effects from intoxication include lesions to the kidneys, the liver, and the heart, as well as damage and bleeding to the lungs.

One characteristic of intoxication from Paraquat is that some symptoms can appear several days after exposure.

Lung tissue accumulates Paraquat more than other organs. People with lung problems are more susceptible to this product. If Paraquat is inhaled, it could produce bleeding from the nose and lung irritation. Because of its low volatility, these intoxications are not frequent and only occur when the product is applied against the wind and without protection.

Paraquat is not absorbed rapidly by the stomach and even more slowly by healthy skin. Several studies show that damaged or irritated skin easily absorb Paraquat (2). The metabolites formed by Paraquat in the stomach are absorbed rapidly, but their toxicity is unknown (12). When Paraquat becomes concentrated in lung tissue it is transformed into highly toxic by-products (3).

In a study conducted on farm animals intentionally intoxicated with Paraquat, it was observed that the animals excreted 90% of the herbicide administered orally. Paraquat was slowly absorbed and metabolized by the gastrointestinal tract. Small quantities of metabolites were detected in milk and eggs (12).

2) Chronic toxicity:

Studies have been preformed by companies that produce or market Paraquat and, of course, they indicate that Paraquat does not produce long term negative health effects.

However, another study conducted with humans concludes that this substance does have chronic health effects on human lymphatic systems (13).

The chronic effects to other organisms have been documented. They are, amongst others, the following:

- Neural toxic effects to rat embryos with permanent effects (14).

- Deformation of rat spermatozoa (15).

- In rats, Paraquat causes permanent deformations to the lungs (16).

E. Environmental Effects

Paraquat is moderately to highly toxic for numerous aquatic species. Aquatic plants can be a source of bioaccumulation. In one study, conducted four days after the application of Paraquat as an aquatic herbicide, the plants analyzed should significant levels of chemical residues.

Paraquat is an embryo toxin to amphibians. In one study conducted by the University of Milan, Italy, it was concluded that Paraquat does not only cause death in tadpoles, but also, many of them show deformations (17).

References

1) MINISTERIO DE SALUD. Estadistica de intoxicaciones. Costa Rica. 1998.

2) WESSELING ET AL. Unintentional fatal Paraquat poisonings among agriculture workers in Costa Rica. In American Journal of Industrial Medicein 32: p 433-441. 1997.

3) MARSTON A., P.A.N.N.A.: Extension Toxicology Network 1999. Personal commuication.

4) HAHN, JR., R.W. and P.A. JENSEN.:Water quality characteristics of hazardous materials. Vol. 1. Texas A&M University. 1974.

5) RAO, P.S.C., DAVIDSON, J.M.: Estimation of pesticide retention and transformation parameters required in nonpoint source pollution models. In Environmental Impact of Nonpoint source Pollution. M.R. Overcash and J.M. Davidson, eds. Ann Arbor Science. 1980.

6) ROJAS, C.E.: Estimación de residuos, degradación y comportamiento de Paraquat en 3 suelos cafetaleros de Costa Rica. Tesis Ing. Agrónomo. San José, Costa Rica. UCR. 58 p. 1984.

7) WAGNER, S. L.: Clinical Toxicology of Agricultural Chemicals. Noyes Data Corporation. 1983.

8) U.S. ENVIRONMENTAL PROTECTION AGENCY. Office of Drinking Water: Paraquat Health Advisory. Draft. 1987.

9) SOLANO, M. . In: La Nacion February 20, 1998; February 24, 1998.

10) STEVENS, JAMES T., SUMMER, DARREL D.: Herbicides in Handbook of Pesticide Toxicology. Volume 3. classes of pesticides. Wayland Hayes and Edward Laws, eds. Philadelphia. 1991.

11) NATIONAL LIBRARY OF MEDICINE. Hazardous Substances Databank. Paraquat. USA. 1992.

12) VETTORAZZI, G. International Regulatory Aspects for Pesticide Chemicals. Volume 1. CRC Press. USA. 1979.

13) SALAM, EL ABIDIN and HUSSEIN, ANWAR EL ITRIBY. The mutagenicity of gramoxone (paraquat) on different eukariotic systems. Ain Sham University, Cairo, Egypt. In: Mutat Res, October 3, 1993. 19 (2), 89-101.

14) FREDIKSSON, A.; FREDIKSSON, M.; ERIKSSON. P.: Neonatal exposure to paraquat of MPTP induces permanent changes in striatum dopamine and behavior in adult mice. Uppsala, Switzerland. In Applied Journal of Pharmocological Toxicology. 1993. 122(2) 258-264.

15) RIOS, AC., SALCADORI, SW., RIBEIRO, LR.:The action of the herbicide paraquat on somatic and germ cells of mice. Federal University of Bahia, Brasil. In Mutat Res. April, 1995. 328 (1), 113-118.

16) EPA R.E.D. FACTS, 1997, 2.

17) VISMARA, C., BATTISTA, G., BACCHETTA, R. Paraquat induced embryotoxicity in Xenopus laevis development. Biology Department, University of Milan, Italy.

III. The Use of Paraquat in Costa Rica

- In 1996, Paraquat, Carbofuran, and Terbufos, three pesticides widely used in banana plantations, caused 57.5% of worker intoxications in Costa Rica (Health Ministry, Costa Rica, 1996). Paraquat was responsible for most of these intoxications.

- In 1997, Paraquat continued to be mentioned on the list of pesticides responsible for poisonings in the country (191 caused by Paraquat out of a total of 827) (23%) (Health Ministry, Costa Rica, 1997).

- In the Atlantic province of Limon, there is the highest incidence of pesticide intoxication primarily due to banana producing activities in the region. In 1997, 91 cases of worker intoxications from Paraquat were reported, out of a total of 305 (30%) (Health Ministry, Costa Rica. Director of Protection of the Human Environment, Permission and Control Dept., State Control of Banana Activities, 1998).

- According to Catharina Wesseling, a collaborating scientist with Costa Rica´s National University, this herbicide could be fatal from contact with the skin, including in low dosages and in people that, for unknown reasons, have a special sensitivity to the chemical ( La Nación, 24-2-1998).

- One transnational banana producer stopped using Paraquat after several years of use, without experiencing a fall in production.

IV. Investigation Summary

A. “Exposition to Paraquat amongst spray operators on Costa Rican Banana Plantations” and commentaries

In 1996, the International Journal of Occupational and Environmental Health published a study about the injuries to workers that fumigate with Paraquat in the Atlantic Zone of the Costa Rica.

The study used 11 cases of workers in 4 different banana plantations. Some workers wore protective equipment, and others did not. The purpose of the study was to oberve the levels of dermal, respiratory, and internal exposure to Paraquat.

Results:

1.) Dermal Exposure: The most affected areas were the wrist, the back, and legs. Even those workers wearing protective clothing suffered dermal exposure.

2.) Respiratory Exposure: All air samples, taken at the face height of operators, contained Paraquat. However, none were at a dangerous level (calculated in studies of animals).

3.) Internal Exposure: Paraquat residues were detected in of 2 of 28 urine samples taken from workers after fumigation.

4.) Systemic symptoms: Two workers suffered nausea, headache, and stomach ache during the investigation.

Commentaries:

This investigation points out three important effects of Paraquat exposure to health:

1- Protective equipment does not prevent dermal exposure.

2- In none of the samples of air did the theoretic concentration of Paraquat reach a level under which long term health effects could occur. However, the risks of combined dermal and respiratory exposure have not been evaluated.

3- There do not exist any investigations that show that Paraquat has chronic health effects. However, in banana plantations workers always run the risk of high, concentrated and extremely dangerous exposure.

Conclusions:

Investigators conclude that “the use of Paraquat in banana plantations cannot be considered safe”.

Recommendations:

-Eliminate the use of Paraquat and replace chemical control methods with mechanical control.

-As alternatives to eliminate risks without eliminating the use of Paraquat, provide adequate maintenance of fumigation equipment, do not allow the operator not mix the solution, and properly train workers.

-As an alternative to reduce the risks of exposure, change the system of paying per job to a system that does not place so much pressure on the worker. When paid per job, operators fumigate rapidly to cover the greatest area as quickly as possible, increasing risks of exposure.

-Protective equipment is considered a final alternative, however its effectiveness is questionalble.

V. Alternatives to Paraquat Use

Of all pesticides, herbicides are the easiest to substitute. While it may be difficult to combat a pest or disease without an agrochemical, invasive weeds can always be controlled mechanically. Additionally, it has been shown that keeping the soil completely bare and “clean” of cover crops is not sustainable. “Weeds”, in fact, serve to protect the soil and are a source of organic material.

As alternatives to Paraquat use, we recommend:

Thermal weeding

Mechanical weeding

Use of natural cover crops

Management with adequate shade

Management with animals (geese, ducks, sheep)

Management of planting density

Considering the danger that Paraquat represents for health and the easiness it can be replaced by other healthy and safe techniqes, there is no reason to continue using it.

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