-from Epidemiological Bulletin, Vol. 23 No. 3, September 2002-

Epidemiological Situation of Acute Pesticide Poisoning
in the Central American Isthmus, 1992-2000

One of the main problems of the 21st century is the degradation of the environment. Scientific and technological advances have generated positive developments for humankind, but they have also opened the possibility of altering the planet’s ecological balance and affecting the health of populations.

Synthetic pesticides are also included in these scientific and technological developments. They are substances primarily used to prevent and destroy agricultural pests. They are beneficial in such that they control insect infestation and increase agricultural production. However, they are designed to destroy living organisms and therefore also create hazards for human and animal health, and the environment. Synthetic pesticides have occupied a significant place among the more than 70,000 chemical substances available on the market since 1940 and they have become the principal strategy for the control of pests. Worldwide pesticide production doubled between 1970 and 1985 and sales, which in 1970 represented US$ 2,700 million, at the end of the century had reached an annual US$ 40,000 million. Approximately 2,800 million kilograms were sold during this period, representing 900 active ingredients and more than 50,000 commercial formulations. The percentage of these substances used in less industrialized countries has increased in the last three decades from 20% to close to 40%.

It is estimated that about 3% of exposed agricultural workers suffer from an episode of acute pesticide poisoning (APP) every year. More than 50% of all APPs occur in less industrialized countries, though the quantity of pesticides used is less. This illustrates the deficient hygiene and safety conditions under which these products are used. In addition to the acute effects, prolonged periods of low level exposure to pesticides can also produce chronic effects such as damages to the central nervous system, congenital malformations, mutagenic effects, cancer, skin, lungs and eye lesions, damage to the immune system, and masculine sterility, among others.

In the seven countries of the Central American Isthmus (Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama), there has been a constant increase in the use of pesticides. In recent years, it reached an annual average of 45 million kilograms of active ingredients, imported and formulated in 42 plants located in these countries. Unfortunately, this increase was accompanied by inappropriate use of the products, deficient storage and production conditions, a lack of understanding of the real health effects due to unspecific symptomatology, and a lack of research on the long term effects of these products on health and environmental deterioration. According to the countries’ registration, 7,000 annual cases of APP are reported every year in this Subregion. However, underreporting is still considerable due to difficulties of farm workers access to health services, erroneous diagnoses, and problems in registration and reporting.

In light of the problem of the intensive pesticide use in the countries of the Central American Isthmus, the Pan American Health Organization (PAHO), through the Division of Health and Environment, has implemented a project (PLAGSALUD in Spanish) that is financed by the Danish Agency for International Development (DANIDA), on the occupational and environmental aspects of exposure to pesticides in the Central American Isthmus. The purposes of this 10-year project, initiated in 1994, are to significantly reduce the health problems related to pesticides and support the implementation of sustainable agriculture alternatives. To reach this goal, PLAGSALUD has been working in partnership with the ministries of health, agriculture, education, environment, and labor, as well as universities and the civil societies in each Central American country. Technical cooperation is provided in the following areas: epidemiological surveillance, research, education, interinstitutional coordination and the strengthening of legislation. Epidemiological surveillance provided valuable information, which was used for the analysis in this report.

The data collection carried out for the present analysis made use of several sources of data and involved the participation of the people responsible for the surveillance of these problems in the different countries of the subregion.

The data on the importation of active ingredients and the use of pesticides by chemical group and by their classification according to which organism they control were obtained from registries of the Ministry of Agriculture for the 1992-2000 period. Based on these data, the trend of pesticide importation for this period was analyzed; further, indicators to evaluate the burden of pesticides were constructed, including the kilograms imported per inhabitant in the general population, per inhabitant in the population economically active in the agriculture, and per hectare devoted to agriculture.

The data on the number of cases of APP from the countries’ epidemiological surveillance system was used for the epidemiological analyses. Taking into account only the cases reported between 1992 and 2000, incidence rates were calculated using the numbers of cases and deaths reported and each country’s population at mid-period. The population data came from projections of the Central American Population Center of the University of Costa Rica. The case-fatality was calculated using the number of deaths due to APP divided by the total of reported APP cases.

These epidemiological data were stratified by sex, age, and cause for the last two years of the series, 1999 and 2000. Proportional analyses were done for each country and for the region. In order to estimate the risk of poisoning in the most exposed population, an indicator was constructed, using the reported cases of poisoning of occupational origin as the numerator and the economically active population dedicated to agriculture as denominator. The data on the economically active population were obtained from the Economic Commission for Latin America and the Caribbean (ECLAC) and the proportion of this population involved in agriculture was obtained from the report entitled “State of the Central American Region”.

The statistical analysis is descriptive, showing trends of the epidemiological indicators by year and country, with proportional distributions to stratify the information by different variables. The cases of APP by sex and cause were estimated from the proportional distributions presented by the countries in their epidemiological information for these variables.

Burden of pesticides in the Central American Isthmus
The population of the Central American Isthmus is currently nearly 35 million inhabitants, half of which live in rural areas, mainly in Guatemala and Honduras. In the countries of the Central American Isthmus as well as in many others of Latin America, a significant proportion of the economically active population works in the agricultural sector. The highest proportion of the territory devoted to agriculture is found in El Salvador, Costa Rica, and Nicaragua, where the main products are coffee, sugarcane, grains such as rice, beans and corn, vegetables, banana, tobacco, and flowers. Between 85% and 90% of the imported pesticides are used in this sector annually, often by communities that have little access to social security or live in areas of limited health coverage.

The importation of Pesticides in the Central American Isthmus has increased progressively. Between 1994 and 2000, it went from 34 to 45 million kg, an increase close to 32% in only 6 years. This subregion presents the highest rate of consumption per capita of these substances, amounting to nearly 1.5 kg of pesticides per person and per year. In 2000, the burden of pesticides per economically active person devoted to agriculture in the region (6.7 kg/person) represents five times that of the general population (1.3 kg/person) (Graph 1). From 1992 to the year 2000, the burden of these substances in the Subregion went from 4.5 kg by agricultural worker to 6. 7 kg.

Among the three principal pesticide groups defined by organism to be controlled, insecticides and fungicides showed a decline in the region during the period, whereas herbicides showed a considerable increase, with importations increasing from 6.3 to 14.6 million kilograms between 1992 and 2000, an increase of 129%.

Acute pesticide poisoning
Acute pesticide poisoning has clinical manifestations similar to many common diseases which signs and symptoms or signs during the physical exam are not specific. Because of this, APP is a cause of morbidity that is often not recognized. Knowledge of the person’s exposure to occupational or environmental factors is of vital importance for diagnosis, treatment, and rehabilitation, as well as for public health purposes. For this reason, it is essential to obtain an adequate history of any occupational or environmental exposure that may cause and even exacerbate a health problem. This also permits to search for other cases in the family, the workplace, or the community and to obtain environmental data. Generally, the registration of cases in Central America is limited in coverage and the levels of underreporting is high. Most of the available data comes from specific studies. However, efforts have been made recently to strengthen surveillance of APP in countries of the Subregion.

The incidence rate of APP in the Central American subregion is close to 20 cases per 100,000 population, with a progressively increasing risk for the period, from rates of 6.3 per 100,000 population in 1992 to 19.5 in the year 2000 (Graph 2). This increase may be related to an increase in surveillance efforts and therefore should be taken with caution. There were 6,934 cases of APP in the year 2000. For this year, the greatest number of cases was registered in El Salvador (2,349), followed by Nicaragua (1,651) and Guatemala (1,060). If the risk is analyzed by country and for the period 1998-2000 - when the epidemiological surveillance system was already functioning - high risk countries with respect to the medium incidence rate are Nicaragua and El Salvador, with rates higher than 35 per 100,000 population, and low-risk countries are Honduras, Belize and Guatemala, with rate lower than 10 per 100,000.

The data obtained through the surveillance system show that the 12 pesticides responsible for the greatest number of APP are Paraquat, Aluminium Phosphide, Methyl-Parathion, Metamidophos, Monocrotophos, Chlorpyrifos, Terbufos, Etoprop, Endosulfan, Carbofuran, Methomyl, and Aldicarb. It should be pointed out that these pesticides are of a high toxicity (levels Ia (extremely dangerous) and Ib (highly dangerous) in the WHO toxicological classification of pesticides). There are less toxic alternatives to all of them and their use could be abandoned.

Mortality from acute pesticide poisoning
The mortality rates also show a rising trend in the period, with a risk of death of 0.3 per 100,000 population in 1992 increasing to 2.1 in 2000 (Graph 2). As in the case of the morbidity data, these could be related to better surveillance and a greater awareness of medical personnel. A slight decline was registered between 1999 and 2000, from 867 to 748 deaths. Comparing the country rates with the average mortality for the 1998-2000 period, El Salvador and Nicaragua are considered high-risk countries with rates higher than 4 per 100,000 population and Belize, Costa Rica and Honduras appear in the low-risk countries with a mortality rate lower than 1.

Case-fatality of acute pesticide poisoning
The case fatality proportion is obtained by comparing the fatal cases to the observed APP. This proportion oscillated between 4.8 and 10.8% in the Subregion between 1992 and 2000. The low fatality level calculated for 1996 (5.4%) may be due to a better detection of non-fatal APP cases. The fatality increase to 11% in 2000 may be due to a gradual improvement of the detection of fatal cases. This proportion is higher in El Salvador, Nicaragua, and Guatemala and indicates the severity of this health problem in comparison with other public health issues in the Region. However, this figure may also reflect a greater capture of the fatal forms of poisoning. It is also important to advance efforts to improve the training of health professionals in identifying and managing cases of APP properly.

Relationship between the burden of pesticides and the behavior of poisoning
The number of kilograms of pesticides imported to the Region and the incidence rates of APP were compared, using the correlation between these two indicators during the study period (1992-2000). A positive correlation was found (Spearman Correlation r=0.83, p=0.005), indicating a steady increase in pesticide imports and in turn an increase in the incidence of APP in the Region over this period. If there is no improvement in occupational safety, this could lead to an increase in the risk of APP associated with pesticide importations and use.

Acute pesticide poisoning according to variables of interest
In people under 15 years of age, 816 cases of APP were registered (5.7 per 100,000 population under age 15) and 27 deaths (0.2 per 100,000) in the Subregion in the year 2000. This risk is smaller than that registered for the total population. Underreporting affecting the entire situation analysis deserves special attention in this age group, even more so because this group is highly vulnerable to exposure to these substances. Acute pesticide poisoning impacts a greater proportion of men, who represent approximately 70% of all cases, with a very similar pattern in all the countries.

The causes of APP presented are based on the following case classification, which depends on the circumstance of exposure:
- Occupational: Exposure to pesticides during work or processes derived from the latter, such as manufacture, formulation, storage, transportation, application, and final disposal.
- Accidental: Exposure to pesticides that occurs unintentionally and unexpectedly.
- Intentional: Exposure to pesticides with intent to cause harm. This includes suicide attempts, suicides, and homicides.

In the year 2000, 36% of the cases of APP were occupational, followed by those with intentional and accidental origins. There are major variations in the proportion of each type of origin by country: in Guatemala, 60% are occupational poisoning, in Belize 50%, in Panama 41%, in Costa Rica 37%, in Nicaragua 33% and in El Salvador 27%. When considering the cases of occupational APP registered in these countries with respect to the economically active population devoted to agriculture, assuming this population is the most highly exposed, incidences reach 48 per 100,000 agricultural workers in 1999 and 37 in 2000, close to twice the risk registered for the general population. Nicaragua, Panama, and Guatemala show a particularly high risk.

Although the reporting of APP has improved in the last two years, the number of cases reported remains low. There are different reasons for the lack of registration of APP, the most important being: 1) the person with APP does not seek care in health centers (by lack of knowledge of the signs and symptoms, fear to lose their employment, difficulty of access to health services, cultural standards not favourable to seeking care, mild cases that do not seem to require care); 2) the person with APP seeks medical care but diagnosis is not done or not reported correctly; and 3) the person intoxicated seeks medical care, is diagnosed and reported, but for administrative reasons the report is not registered in the epidemiological surveillance system.

In light of this situation, the PLAGSALUD project conducted a study of underregistration in each of the seven countries during the year 2001. In six countries it was accomplished through community surveys and in one through administrative underregistration research (analysis of the information system that supports epidemiological surveillance in the health system). The general underregistration results were the following:

Belize: 99%
Costa Rica:

Canton #1: 97.8%
Canton #2: 96.7%
Canton #3: 91.2%
Canton #4: 82.2%

El Salvador: 97% (municipal level)
77% (departmental level)
80% (national level)
Guatemala: 97.5% (municipal and departmental level)
Nicaragua: 98.9%
Honduras: administrative underregistration was less than 20%
Panama: 93.6%

The previous information implies that, in general, between one and 20 of every 100 cases of APP are reported, except in Honduras where only administrative underreporting was studied.

One important point to mention is the progressive increase in pesticide importations in the Region over the last decade. This increase was registered in many countries and when the pesticides are classified by type of organism it is designed to control, herbicides show a rising trend. Compared to the WHO estimates of an average pesticide burden at the global level of 0.6 kilograms per person, the burden in the Region remains very high. For 2000, the Regional incidence rate was close to 20 cases per 100,000 populations and the mortality rate was 2.1 per 100,000 populations. Cases of acute poisoning and mortality also show a rising trend. This trend may reflect a better registration system or problems due to a poor management or a greater dangerousness of this type of substances. Nicaragua and El Salvador show the highest risk. However, given the increase in imports of these substances in countries such as Guatemala and Honduras, the lowest risk may reflect an underregistration problem. The case fatality associated with pesticide poisoning is high. In 2000, 11% of the APP cases resulted in death. As a response, health personnel should be trained in the management of these situations, and strict prevention and control activities should be put in place. Major efforts should be made to develop and implement strategies that lead to a drastic reduction of the use of synthetic pesticides, to the development of alternatives and subsequently to the protection of human health and the environment. Different initiatives supported by PLAGSALUD in the Centroamerican Isthmus are presented in Box 1.

Recommendations for surveillance, prevention and control of acute pesticide poisoning
In light of these major challenges facing Central America to control these problems, we can mention the following:
– Promote epidemiological surveillance systems that permit the constant monitoring of patterns of the problem both in terms of human health and the environment, in order to correctly direct prevention and control activities in a more effective and pertinent way. This requires the improvement of the quality of the data.
– To better analyze occupational poisoning, it is necessary that each country of the region generate more precise and reliable case data.
– Improve epidemiological surveillance actions that are being put in place with regard to: poor completion of notification reports, more detailed analysis by cause and most often found pesticides; period of the year in which the poisoning occurs; toxicological classification of the pesticides; and severity of the poisoning, among others.
– Support the development of alternatives to pesticides, such as integrated pest management (IPM) and organic agriculture, which constitute a production system based on appropriate management practices. These practices should take into account conditions for biological activities in agrosystems to be developed appropriately, i.e. in a less dependent, polluting and dangerous way.
– Promote and organize citizen participation, particularly that of the most exposed workers and communities, permitting direct involvement in the decision-making process in the different territorial entities. For that to happen, access to up-to-date and complete information on pesticides is required.
– Establish controls for pesticides posing greater human health and environmental hazard through: prohibition of pesticides in their countries of origin, prohibition of substances belonging to persistent organic pollutants, homogeneity of pesticides prohibited in all the countries of the subregion, strictest controls for the sale of products that have produced the greatest number of APP, adequate elimination of residues and containers, prohibition of application by women and children, and selection of pesticides based on molecules found in fungi, bacteria, and plants that act on the pest organism and induce resistance of the same.
– Better controls on compliance using existing legislation.
– One of the biggest problems in the subregion is the standardization in all the countries of the list of prohibited pesticides. This standardization is required in order to improve controls at customs, in the field, at the points of sale, and generally in the enforcement of existing legislation.
– Improve the conditions of hygiene and safety for farm workers and their families, who are the population with greater exposure to these substances.


Box 1: Initiative of prevention and control of APP supported by PLAGSALUD in the Central American isthmus

The following are among the initiatives developed for the prevention and control of the different health and environmental problems derived from the use of pesticides:

The ministers of health of the countries of the subregion ratified, during the XVI Special Meeting of the Health Sector of Central America and the Dominican Republic, an agreement on restrictions and prohibitions of Pesticides (Agreement no. 9). Through this agreement, it was requested of the ministries of health, agriculture, environment and natural resources to initiate the process of restricting the 12 pesticides responsible for the greatest morbidity and mortality by APP in the Central American Isthmus (Methyl-parathion, terbufos, etoprop, aldicarb, metamidophos, methomyl, monocrotophos, carbuforan, endosulfan, aluminium phosphide, paraquat and chlorpyrifos). Furthermore, in order to bring about stronger legislative actions, the countries were urged to standardize the prohibition of 107 additional pesticides currently prohibited in one or more countries. El Salvador and Nicaragua have spearheaded this process by prohibiting 35 and 17 pesticides, respectively in 2000 and 2001. In Belize, control is being performed through a classification of pesticides of restricted use, listing the 40 most toxic insecticides. A special license is required to buy these substances.

Epidemiological Surveillance
Surveillance of acute pesticide poisoning was incorporated in the surveillance systems of the seven countries. With the information obtained in the countries, it has been possible to design prevention and control strategies to intervene on the risk factors. Furthermore, environmental surveillance has been strengthened, through studies of pesticide residues in food in several countries, and the monitoring of the presence of pesticides in the environment, specifically in water, as occurred in the flooded areas of Honduras after Hurricane Mitch.

Community participation
One of the most effective and practical results of PLAGSALUD is the creation in the seven countries of over 350 intersectoral local commissions on pesticides (CLIPs for their Spanish name, “Comisión local intersectorial de plaguicidas”), which gather hundreds of members working at the local level, from farmers to government workers, community representatives and NGO workers. These commissions are the most lively expression of the day to day work carried out in Central America to reduce the negative effects of pesticides, to educate the general population on the risks of these substances, and to find and apply alternatives to these substances.

Educational material has been prepared, both at the subregional and country level, for workers, the community in general, technicians and professionals of the health, agriculture, labor, education, and environmental sectors. Guatemala is making particular efforts in education. In the last three years, 30,000 people have been trained in insecticide management and alternatives to these, with an emphasis in the six regions with greater problems. These educational activities have been carried out using the translation of educational materials in several Mayan tongues. Formal education has also been encouraged through distance learning courses, continuing medical education to health personnel and other nonmedical personnel working in poisoning prevention and the control of environmental pollution by these substances.

Search for alternatives to pesticides
The development of alternatives has meant working with Integrated Pest Management (IPM) and organic agriculture as a priority in all the countries of the subregion. Guatemala, Nicaragua, and Costa Rica are the countries that devote the greatest land surface to organic production. Through this alternative, the countries hope to obtain a higher quality agricultural production, to reduce the use of pesticides and to open new alternatives for small farmers. Currently, 41,000 hectares are used for organic agriculture, for products such as banana, beans, cacao, coffee, and blackberries.

Aguirre, Elba. Informe de intoxicaciones por plaguicidas. Costa Rica, 1999-2000. San José, Julio de 2001. pp. 1-16.

ASDI/OPS, XVI Reunión del Sector Salud de Centroamérica y República Dominicana (RESSCAD), Informe Final, Honduras, 2000.

CEPAL. Población económicamente activa 1980-2000. Santiago de Chile, Boletín No. 64. Consultado en Octubre de 2001. http://www.cepal.cl/publicaciones/poblacion/9/LCG2059/BD64.html

Corriols, Marianela. Indicadores agro sanitarios de la exposición laboral agrícola a plaguicidas en Nicaragua. Manejo Integrado de Plagas, CATIE, Costa Rica. No. 60. pp. 88-92, 2001.

Costa Rica, Universidad de. Datos demográficos. Centro Centroamericano de Población. San José, 2001.

Chile, Ministerio de Salud. Situación epidemiológica de las intoxicaciones agudas por plaguicidas. Chile, 1998. Departamento de Epidemiología, Red Nacional de Vigilancia Epidemiológica de Plaguicidas. Santiago de Chile, 2000. pp. 7-20.

Henao, Samuel. Utilización de plaguicidas sintéticos, un problema por resolver en el nuevo milenio. Manejo Integrado de Plagas, CATIE, Costa Rica. No. 55. p. 70-72, 2000.

Kegley, Susan. California Pesticide Use Update. Global Pesticide Campaigner. San Francisco CA. August, 2001; 11(2): 4.

OPS/OMS. PLAGSALUD. Special Section MASICA Review. Pesticide free. Central America attemps to revert indiscriminate use. San José, Costa Rica, February, 2001. pp 1-48. OPS/OMS. PLAGSALUD. Plaguicidas y salud en el Istmo Centroamericano. Washington, Noviembre, 2001 (En edición).

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Source: Prepared by Dr. Samuel Henao from the Environmental Quality Program (HEQ) of PAHO’s Division of Health and Environment (HEP) and by Dr. Maria Patricia Arbelaez from the Public Health Department of the University of Antioquia, Medellin, Colombia.

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Epidemiological Bulletin, Vol. 23 No. 3, September 2002