June 1997

Introduction

Mexico's experience on the eradication of DDT's use

Objective

The objective of this North American Regional Action Plan (NARAP) on DDT is to reduce the exposure of humans and the environment to DDT and its metabolites through joint efforts of the three countries and a cooperative approach that includes the sharing of experiences with other countries of the Americas. This NARAP proposes to accomplish this program through the phased reduction, leading to the eventual elimination, of DDT used for malaria control in Mexico, as well as the elimination of illegal uses of DDT.

Guiding Principle

This NARAP supports:

• a holistic approach to malaria control, bringing together an integrated pest management strategy for the vector as well as the full spectrum of related public health activities and services;
• ongoing and new cooperative activities to achieve the goals of Canada, Mexico and the United States under this NARAP;
• partnerships with industry, public interest groups and international organizations in Canada, Mexico and the United States to involve them in NARAP implementation;
• a regional perspective that encourages sharing experience with other Caribbean and Latin America countries and involving them to ensure that malaria continues to be controlled throughout the region; and
• participation in and building upon related global initiatives.

Rationale

DDT is a persistent, broad spectrum pesticide that in the past has been widely used in agriculture and for the control of mosquitoes, black flies and other insect pests and disease vectors. Some developing countries still use it in malaria campaigns, not only because of its effectiveness, but also because of its low cost and lack of acute toxicity for applicators, compared to alternative chemical pesticides that are more costly or more toxic. However, DDT and its metabolites are persistent, bioaccumulative and can be transported long distances through the atmosphere. Residues of DDT and its metabolites in the environment have been shown to result in adverse effects on wildlife reproduction. They continue to occur at reduced levels in environmental media in the North American region. The 114 member countries of the Intergovernmental Forum on Chemical Safety (IFCS) agreed that there was sufficient evidence to warrant international action on Persistent Organic Pollutants (POPS), including DDT (IFCS/Forum-II/97). This was the basis for the decision of the Governing Council of UNEP (in January 1997) that a legally binding, international instrument be developed for the control of POPs. This NARAP is intended to serve as a basis for a coordinated regional response to these international initiatives.

The manufacture, sale and use of DDT has been eliminated or substantially reduced in North America. Current DDT production is restricted to one facility in Mexico, which supplies DDT for authorized government use in malaria vector control. Mexico continues to operate a comprehensive malaria control program that has substantially reduced the incidence of this disease, while gradually decreasing the reliance on DDT. It is estimated that, thanks to this program, an additional 80 percent reduction in DDT use will be achieved in five years.

This NARAP was developed by the Parties to the North American Free Trade Agreement (NAFTA), working with the Secretariat for the (North American) Commission for Environmental Cooperation (CEC), under Council Resolution #95-05, Sound Management of Chemicals, agreed to by the Council of the CEC. New research on the human health effects of long-term exposure to DDT, and the continuing need for an effective and comprehensive malaria control program in Mexico, provide additional incentives for regional action. This NARAP could serve as a guide to other countries in Latin America, be a useful template for action by other regions, and support global initiatives. This also represents an opportunity for other countries to benefit from a better understanding of Mexico's holistic approach to malaria control. The practical experience gained in responding to the socio-economic realities in implementing this NARAP may serve as a useful example to other countries in Central America and to other regions.

Background

Canada

DDT was first registered in 1946 and used in Canada to control insect pests in crops as well as in domestic and industrial applications. DDT was never manufactured in Canada. In response to environmental and safety concerns, most uses of DDT were phased out by the mid-1970s. Registration of all remaining uses of DDT was discontinued in 1985 with the understanding that existing stocks would be sold, used or disposed of by 31 December 1990. After this date, any sale or use of DDT in Canada represents a violation of the Pest Control Products Act.

The gradual restriction of the range of permitted uses of DDT was facilitated by the availability of effective alternatives. The phased reduction was also important in that it helped to avoid the creation of a large-scale disposal problem.

Provincial legislation provides additional regulatory powers to control the transportation, storage, disposal and use of pest control products, taking into account regional conditions and concerns. Municipalities may also control aspects of pesticide use and disposal. Some of the earliest pesticide collection programs at the municipal-level were set up in the 1960s and 1970s to collect and dispose of DDT. These programs were developed to manage unused stocks of certain formulations of DDT, resulting from the regulatory decisions to limit the permitted uses.

Pesticides that are not legally registered in Canada are refused entry and returned to the exporter. The Importation for Manufacturing and Export Programme for Pest Control Products does not allow for the importation of DDT for the purposes of reformulation and subsequent exportation. In addition, exports of DDT would be subject to notification according to the Canadian Environmental Protection Act, and no such notifications have been received.

Since the mid-1980s, programs have been set up at the provincial and municipal level across Canada to collect hazardous wastes. These programs generally include pesticides that are no longer used, have been discontinued, or were banned. Hazardous waste management facilities handle the products in accordance with federal and provincial guidelines.

In most provinces, rural collection programs have been established at different times specifically to collect pesticides that were no longer being used. One example is the Ontario Ministry of Agriculture and Food and Rural Affairs which in 1991-92 conducted the Ontario Waste Agricultural Pesticide Collection Programme. This program was widely publicized and collected approximately 1,180 kilograms of DDT. A subsequent pilot project, the Pesticide Disposal Pilot Project to dispose of waste registered and unregistered pesticide products, was initiated in August 1995. As of August 1996 no DDT had been brought forward for disposal. Limited quantities (e.g., 300 grams) of DDT have been reported in municipal collections of Household Hazardous Waste Collection programs, though information on specific chemicals is not available from all sites.

There are no maximum residue levels for DDT in Canada. Action levels for residues of DDT and its metabolites in foods have been established, ranging from 0.5-1.0 ppm in eggs, fresh vegetables, dairy products, meat and meat byproducts to 5 ppm in fish. These levels have been established based upon monitoring information collected on domestic and imported foods and are periodically revised as new information becomes available.

The United States

In 1969, the US Department of Agriculture (USDA) cancelled the registration of certain uses of DDT (on shade trees, on tobacco, in the home, and in aquatic environments) after studying the persistence of DDT residues in the environment. Applications on crops, commercial plants, wood products, and for building purposes were cancelled by the USDA in 1970. Under the authority of the EPA, the registrations of the remaining DDT products and DDT-metabolites were cancelled on 4 January 1973, with the following exemptions: public health use for control of vector-borne diseases, USDA or military use for health quarantine, and use in prescription drugs for controlling body lice. All of these remaining uses were voluntarily cancelled (due to failure to pay maintenance fees) by October 1989. The fact that there are no registrations means that DDT cannot be used in the United States, nor can it be imported for use as a pesticide product. At present, the United States does not have the legislative authority to prohibit production of DDT if a manufacturer wanted to initiate such production in the future.

However, DDT is not currently manufactured in the United States. There have been recent reports of DDT exports and imports entering or leaving the United States. The EPA believes that the exports are actually small quantities of reference standards being shipped between laboratories and as such, they are subject to the export notification requirements of the Toxic Substances Control Act (TSCA), which has no de minimis cut-off for notification. The imports may also have occurred when the Department of Defense (DOD) recalled its existing stocks for destruction. The DOD no longer uses DDT in any of its operations abroad and does not maintain a stockpile. No maximum residue levels are in effect, although there are numerous action levels for a wide variety of crops, ranging from 0.05 ppm to 5 ppm.

Mexico

The introduction of DDT in Mexico in the early 1950s for its use in agriculture followed the pattern ahown by Canada and the United States. In the 1970s, DDT use in agriculture production began to decline as a result of environmental concerns and the introduction of stricter limits on residues of DDT on foods.

Today, DDT is registered in Mexico only for use in government-sponsored public health campaigns. It continues to be an important tool in the fight against malaria transmission. Mexico's malaria control program restricts the use of DDT to selective applications in dwellings. There is only one private company producing DDT in Mexico, and its production is subject to government approval. DDT requirements for malaria control have been reduced significantly in recent years because of changes in Mexico's malaria campaigns.

It is important to understand that malaria is a long-standing public health problem that has inhibited development in large areas of the country. Sixty percent of Mexico's territory from sea level to 1,800 meters above sea level, presents favorable conditions for malaria transmission. This includes the Pacific coast, the Gulf of Mexico slopes, the Yucatán peninsula and interior basins of the high plateau. Some 45 million people live in these areas. In the 1940s and 1950s, malaria was one of the main causes of mortality, responsible for an average of 24,000 deaths annually and afflicting an estimated 2.4 million others. In recent years, the incidences of malaria have declined significantly, to less than 5,000 cases, indicating the success of Mexico's malaria control program. Since 1982 there have been no deaths from malaria. The Appendix provides more detailed background on malaria and DDT use in Mexico.

The creation in 1987 of an Interministerial Commission for the Control of Production and Use of Pesticides, Fertilizers, and Toxic Chemicals (Cicoplafest), formed by the Ministries of Health, Urban Development (now Environment), Agriculture, and Trade, has been instrumental for the banning of the use of six organochlorine pesticides and the restriction of DDT use. The production of DDT has declined steadily and is presently less than 600 tonnes per year.

In 1995, Mexico decided that an integrated pest management approach for malaria could substitute for the heavy dependence on pesticides. Improved sanitation, surveillance and minimum use of pesticides to control mosquitoes and larvae are considered key elements in this new approach. Furthermore, in 1996, Cicoplafest implemented a new initiative to control pesticides with a life-cycle approach, and the new Health Law, published in 1997, introduced the concept of safe management of chemicals throughout the entire life cycle. In April 1997, the Ministry of Environment, Natural Resources and Fisheries, through its National Institute of Ecology, published a Program for the Environmental Management of Priority Toxic Chemicals that mentions the development of this DDT NARAP. Under all these initiatives, organochlorine pesticides have been considered priorities for regulatory action due to their persistence and tendency to bioaccumulate.

Goals

Supported by Canada, Mexico and the United States, DDT is one of the initial targets of the Sound Management of Chemicals initiative under the North American Agreement for Environmental Cooperation (NAAEC), and through the joint efforts of the three countries it will be assured that malaria continues to be controlled.

The following specific goals provide a baseline against which to measure progress. The identification of proposed target dates does not preclude the possibility of achieving these goals within a shorter time period.

The specific goals of this NARAP, directed at its overall objective, include:

• DDT use in malaria control in Mexico will be reduced by 80 percent in five years. This reduction will build on the current national program and will be achieved through a coordinated/integrated management approach with active participation of the affected communities. Future reductions will be achieved based on cooperative action and experience.
• Illegal uses of DDT in agriculture will be eliminated.
• A cooperative approach in the region will be pursued to:
  1. minimize movement of malaria-infected populations across borders and
  2. reduce the illegal importation of DDT.
• Cooperation in international fora will be increased to advance global controls on DDT production, export and use.

Actions

The Task Force on DDT and chlordane has acknowledged that achieving the goals of this NARAP will be a iterative learning process where efforts will be concentrated on initiatives shown to have the greatest potential for success. Adjustments to the initiatives may be required as experience is gained during their implementation. In undertaking to follow the steps proposed in this NARAP, the Parties are committing themselves to ongoing cooperative activities and the yearly reporting on progress made on the initiatives and objectives. Such reporting will be made to the North American Working Group for the Sound Management of Chemicals, and subsequently disseminated to the Council of the Commission for Environmental Cooperation and the public.

The initial geographical emphasis of the action plan will be placed on selected sites within those areas identified as foci of persistence by the current malarial control program, as they are already well characterized. The studies in this phase will be used to develop and validate relevant methodology. The experience gained will be used to review the proposed approaches and consider how they might be extrapolated to other sites in Mexico.

A regional perspective that encourages the active involvement of other Central and South American countries in the implementation of this NARAP is seen as important to its success. This will require sharing Canadian and US experience in the combat of malaria, and close cooperation with existing programs and activities for malaria control throughout the region and subregion, including those coordinated by the Pan American Health Organization (PAHO) and other regional and bilateral initiatives.

It will be important to establish priorities and timeframes for all of the activities initiated under this NARAP, develop precise estimates of costs, have a clear understanding of how to measure progress in achieving goals, and promote all means of cooperation that can aid the process.

Specific NARAP Actions

Alternative Vector Controls

Alternative methods for malarial control in Mexico will be developed to support the continuous reduction and eventual elimination of DDT use. In assessing the acceptability of alternative chemicals, full consideration will be given to their potential impacts on human health and the environment throughout their life cycle under the conditions of use in Mexico. The first step will focus on the development of clear baseline information on current activities and previous experience with alternative chemicals and biological vector controls.

The initial phase of this NARAP will test alternatives to DDT, including biological controls and public health and education initiatives, and will continue to focus on the interruption of malaria transmission. More specifically, projects will include consideration of the following points:

1. As a priority, seek to promote the biological combat against malaria vectors. The focus of this work will be on promoting an integrated pest control program, not on the substitution of one chemical agent for another. Key elements will include testing the effectiveness of biological alternatives through supporting research on the development of biological methods, such as the use of parasites of larvae, predators of adults and microbial products such as Bti (Bacillus thuringiensis serovar israelensis); and the development and implementation of plans for ecological improvement and restoration (e.g., natural control of mosquito populations). The reduction of breeding sites, through improved sanitation, drainage programs and landfills as appropriate, will be emphasized. In assessing the risks of alternative pesticides, the results of NOT controlling malaria will be considered as well.
2. Evaluate the management of insecticides, study the health and environmental impacts in selected study areas, and develop and implement a scheme to monitor levels and effects of insecticides used in the malaria campaign on humans (i.e., insecticide applicators and people living in treated dwellings), the environment, and selected animal species (aquatic and terrestrial), with particular attention to the pests' susceptibility to alternative control measures, and levels of resistance.
3. Compare the effectiveness of alternative pesticides with DDT in controlling the malaria vector within human dwellings (including their application to and the use of bed nets). This analysis will include full cost accounting, encompassing specific substitution costs, general public health costs, health and environmental effects.
4. Strengthen programs to test the effectiveness of alternative insecticides in reducing mosquito populations in and around communities. As part of these comparisons, the costs, health and environmental effects, and other parameters affecting the integration of alternative chemical insecticides into the control program will be considered.

Developing these initiatives will include considering the possibility of their integration into the current malaria control program. Canada and the United States will work closely with Mexico in providing available risk assessments for those alternatives (chemical and biological) identified as likely candidates. In the longer term, the ongoing efforts of the NAFTA Technical Working Group on Pesticides will assist Mexican authorities.

Public Health

This NARAP represents an opportunity to strengthen existing intersectoral cooperation in the provision of public health services. Regional cooperation will be pursued to promote the early detection and immediate treatment for workers infected with malaria and others migrating from Central America to Mexico who may be infected, to reduce malaria transmission, and to improve malarial control in surrounding countries. The following points summarize the initiatives to be undertaken in Mexico:

1. Health services coverage needs to be improved for:
   • early detection and immediate treatment for those exposed to malaria,
   • monitoring demographic movements and reducing the influence of these movements on malaria, and
   • environmental sanitation and hygiene (through a cooperative, intersectoral approach).
2. The means for exchanging information (through written materials, Internet communication, workshops or visits of personnel involved in malaria campaigns, etc.) should be established with other countries in the region.

Public Participation and Education Activities

As spelled out in the following points, this NARAP will seek to promote public participation in the development and implementation of special activities in affected communities, as well as to increase public awareness. This will include cooperation with industry, public interest groups and other nongovernmental organizations.

1. Parties will communicate basic information (in an appropriate form for public education materials) on this NARAP project, concerning the health and environmental effects of DDT and those of proposed alternatives. The materials will include specific guidance on vector habitat controls and information on community hygiene practices that reduce habitats and breeding sites. The guidance will also explain the merits of personal protection methods (such as bed nets, etc.).
2. Community participation will be sought for the development and implementation of the projects, and to ensure that local community organizations are kept informed.
3. Additional information about illegal DDT use in agriculture and guidance and advice on alternative practices will be provided.
4. Effective ways of disseminating information and educational materials will be developed.

Industrial Sector

North American industry will be encouraged to support the identification and evaluation of alternative pesticides compared to DDT. It is suggested that industry support could include:

• assessing the effectiveness of alternative pesticides;
• defraying the costs of testing possible alternatives during a two-year period (an estimation will need to be made of the number of dwellings and applications of the insecticides in the operational trials during that period);
• training of applicators;
• change of equipment (if needed);
• evaluation of insect resistance.

The production of DDT in Mexico will be maintained according to the needs of the Mexican malarial control program. Phase-out of DDT and cancellation of its registration as a pesticide will occur after viable, effective alternatives have been financed and tested.

Enforcement

Intersectoral, cooperative programs will be strengthened to control illegal and non-authorized uses of DDT, partially through the control of illegal importation, sale and use of DDT in the North American region, and partially by Cicoplafest reinforcing DDT-surveillance activities.

Waste Management

The gradual phase-out and use of DDT, and the controlled reduction in production, will for the most part avoid the creation of stockpiles of an obsolete pesticide, thereby avoiding the need for an extensive waste management program.

Canada and the United States will continue to support DDT-inclusive hazardous waste collection programs at the federal, provincial/state, or municipal level, as appropriate. The information on how these programs are run will be shared with Mexico, which in turn will administer its own hazardous waste collection programs.

Integration with International Activities

1. The experiences gained under this NARAP will be shared with Latin American and Caribbean countries to reinforce the implementation of the World Health Organization's Global Malaria Control Strategy.
2. Canada, Mexico, the United States, and the CEC will continue to cooperate within the framework of the Sound Management of Chemicals initiative and the North American Working Group on the Sound Management of Chemicals. This cooperation will benefit from the activities of the NAFTA Technical Working Group on Pesticides to strengthen information-sharing activities and provide scientific advice and support as appropriate on technical and regulatory issues.
3. Canada, Mexico and the United States will work together within the global framework to reduce or phase out the use of DDT and share experiences gained in the development and implementation of this NARAP with other countries in Central America and other regions.
4. As appropriate, the relevant international organizations will be involved.
5. Once agreement has been reached on the international procedures for prior informed consent, the United States will seek the necessary legislative and administrative authority necessary to meet its obligations under the agreement.
6. Concerning the exportation of DDT, Mexico will encourage the producing company to comply with the principles of the prior informed consent procedure in order to honor the wishes of importing countries.

Implementation

Canada, Mexico and the United States and the CEC will work cooperatively to develop scientific and otherwise detailed proposals for NARAP initiatives and approach aid and technical cooperation agencies for obtaining the substantive funding needed to implement the actions in this NARAP.

Reporting

1. Canada, Mexico and the United States will report in 1997 on the use, production, importation and exportation of DDT, and any possible violation of domestic regulations.
2. Canada, Mexico and the United States will report annually to the North American Working Group on the Sound Management of Chemicals on progress under this NARAP and on the support for its implementation that has been generated through cooperation.

Appendix-Presentation by the Mexican Ministry of Health

Introduction

[Note: The report upon which this edited text is based was provided by Mexico and presented (Document IFCS/EXP POPs 11) on 14 June 1996 to the Intergovernmental Forum on Chemical Safety at the opening session of the IFCS Experts Meeting on POPs, held 17-19 June in Manila, Philippines.]

For many years malaria has been a major public health problem in Mexico-one that has hindered the development of large areas of the country. In the 1940s and 1950s it was one of the main causes of death, causing an average of 24,000 mortalities annually and afflicting some 2.4 million individuals.

At the end of the 1940s, a program of selective spraying of DDT in dwellings was begun in some urban and rural areas, yielding results that supported the international eradication proposal presented by Mexico in 1955. Even though this national campaign for malaria eradication did not accomplish all its objectives, the transmission of Plasmodium falciparum was halted, the death rate from the disease was greatly reduced, and efficient technical and operational procedures were established which allowed other public health programs to be introduced in rural locales with difficult geographical access.

The widespread introduction of DDT in Mexico followed the pattern of many other countries. During the early 1950s, DDT was introduced throughout Mexico and extensive agricultural use followed. As much as 1,000 tonnes per year were applied to large agricultural areas, and application rates in the Laguna region in central Mexico were among the highest in the world.

The success of DDT spraying in the household to reduce malaria transmission became strategic in the 1960s, and the evolution of the spraying campaign typifies the intensity placed in the campaign against the disease. From the selectively based campaign of the 1940s, the use of DDT and other newly developed organochlorine pesticides grew steadily through the 1960s. Finally, in 1968, DDT production was bought by the government for state control. This was also the time in which organochlorine production peaked in Mexico, with more than 80,000 tonnes produced annually.

The controlled production of DDT resulted in increased availability and lowered cost for its use in malaria control and agriculture. However, production was maintained at about 25,000 tonnes per year. During the early 1970s the US Food and Drug Administration (FDA) began rejecting the importation of commodities due to high residue levels, especially of DDT.

The growing concern about DDT persistence has had a significant impact on agricultural practices in Mexico. The northern area of the country, more developed and highly dependent on exports, changed to newer and even more toxic pesticides in order to comply with FDA/EPA regulations on DDT residue content. The southern area of Mexico, largely devoted to local production, continued the use of organochlorine pesticides. However, the use of DDT in agriculture started to decline. In 1987 the Ministries of Agriculture, Commerce, Urban Development (now Environment) and Health joined efforts by forming an interministerial commission to control the use of pesticides, fertilizers and toxic substances. In 1990 this commission (Cicoplafest) banned the use in Mexico of six organochlorine pesticides and DDT use was severely restricted. Organochlorine production declined steadily and DDT was limited to campaigns addressing public sanitation (about 3,000 tonnes per year).

In the early 1980s, the economic crisis and reductions in program activities caused a significant deterioration in public health, leading to the temporary increase of malaria transmission. In 1985, 133,700 cases were registered in 14,000 localities. As a result, the malaria control program was strengthened with additional human, material and financial resources. The technical strategy was reoriented to address the simultaneous elimination of the plasmodium parasite in humans and the anopheline mosquito as disease vectors. From 1985-89, the annual average had declined to 117,000 cases. Still, in 1989, among 21 countries in the American hemisphere with active programs against malaria, Mexico reported nine percent of the cases, second only to Brazil in number. By 1994, after the reinforcement of the anti-malarial program, the number of cases had decreased to only one percent of those reported in the Americas.

In 1991, Fertimex, the national producer of DDT, was privatized and additional restrictions were placed on organochlorine production. Changes in malaria campaigns have further reduced DDT use and production.

In 1996, Cicoplafest undertook a new role. Pesticide control through the life-cycle approach has been implemented and new governmental areas (transportation and labor) have been included to integrate every area of the chemical life cycle. Elimination of organochlorine pesticides is a priority, due to their persistence and tendency to bioaccumulate.

Aspects of Malaria Prevention and Control Programs in Mexico

The anti-malarial program is geographically oriented, since 60 percent of the territory from sea level to 1,800 m above sea level presents favorable conditions for the transmission of the disease. This includes the Pacific coast and Gulf of Mexico slopes, the Yucatán peninsula and interior basins of the high plateau. The area encompassed is inhabited by close to 45 million people. The strategy focuses on entomological and epidemiological stratification of the malarial areas, since studies have revealed that 70 percent of malaria cases were located in approximately one thousand pockets of persistence, distributed throughout five states that have high receptivity and vulnerability due to national and international migration. Thus program activities have been divided into two areas:

1. For non-priority states: Intensification of epidemiological surveillance, selective application of DDT spraying to dwellings, and intensive treatment of diagnosed cases.
2. For priority states the Intensified Action Plan will be applied:
   • 2.1 Selection and training of personnel in epidemiological, therapeutic and entomological aspects of malaria transmission and prevention, use of pesticides and spraying equipment (personnel skills and aptitudes are taken into consideration). Thus far, 2,422 workers have been trained through 90 short courses. In addition, other program staff are updated twice a year
   • 2.2 Promotion of active community participation in the program and inculcate a public health self-care mentality in the population so people will demand health services of public medical units and notification centers headed by voluntary members of rural communities.
   • 2.3 Promoting basic sanitation aimed at reducing human contact with disease vectors. This includes clearing overgrown areas; cleaning up bodies of water; improving drainage of stagnant water, and bringing about general improvements in housing conditions, including promoting the use of beds, and window and door screens.

Activities

• Entomological studies have identified 26 species of Anopheles mosquitoes in Mexico. The main malaria vectors are: A. pseudopunctipennis and A. albimanus. The first, widely distributed in malarial areas of the country and the primary vector in the Pacific slopes, is found from the coast up to 2,000 meters above sea level; the second is found from sea level to 800 meters above sea level and is the main vector in coastal areas along the Gulf of Mexico, in the Yucatán peninsula, and in the forests of Chiapas.
• Entomological surveillance includes: a) hydro-entomological monitoring of bodies of water in areas where the anopheline mosquitoes are found; b) capture of adult mosquitoes around dwellings, including animal lodgings and natural shelters, during the period of hematophagous activity; c) determination of parity; and d) testing resistance to each insecticide used in the program, using methodologies and equipment recommended by the World Health Organization.
• Disease notification is considered a crucial aspect of the epidemiological surveillance of malaria. In Mexico approximately 30,000 notification centers have been established and staffed by volunteers. Each year they draw 11 percent of the two million blood samples that are examined and notify around 43 percent of the total cases reported.
• Monitoring of fever victims at home is performed on a monthly basis by specific personnel involved in the program and voluntary notifiers, giving priority to localities considered as foci of persistent transmission.
• Microscopic examination of blood samples is handled by 140 local laboratories located through the malarial areas, where each year an average of two million blood samples are examined in the course of epidemiological surveillance. Cases diagnosed are identified and controlled by name in order to allow efficacy of treatment, which includes doses of chloroquine-primaquine for a period of five consecutive days.
• Intensive medical treatment for humans in foci of disease persistence centers on the elimination of plasmodium parasite in the blood and liver.
• Action against the mosquito vector begins, through entomological surveillance, with the identification of foci of disease persistence and those sites and hours of the day and night when vectors concentrate to feed and rest after feeding. This information allows selective malathion fogging to be most effective.
• Anti-larval activities, related to improved sanitation, involve the elimination of mosquito breeding sites through drainage or filling of low-lying areas, involving community participation. When these measures are not feasible, the larvicide, temephos, is selectively applied simultaneously with the fogging in breeding sites.
• Statistics are gathered weekly by collecting epidemiological data by locality, municipio, and state, giving monthly operational data for each program unit and level.
• Program supervision strives to correct errors and omissions through in-service training, improving skills and personnel attitudes.
• Monthly evaluations are performed at each level (team, section, sanitation jurisdiction, state and national), comparing program goals with results obtained in each field activity.
• Applied operational testing has included field and laboratory research on procedures for eliminating the plasmodidiæ parasites, including house spraying with bendiocarb and fenitrothion, which underwent testing for four years.
• DDT spraying of households continues to be a successful part of the program. The number of households sprayed has diminished, though, as persistent foci have been eliminated. Currently fewer than 600,000 treatments are required nationwide.

Current Legal Status of DDT Production and Use in Mexico

Currently DDT use is severely restricted in Mexico and has been registered and approved only for anti-malarial control programs. The pesticide is classified as a persistent compound with an acute toxicity that is low for humans and but high for animals. Chronic effects, though, are a serious consideration, due to its possible link to breast cancer and reproductive abnormalities.

Legally DDT production is limited to public health needs and for international trade. Two certified concentrations are available: technical grade (100 percent pure) for use in mixing formulations and 75 percent for household application. Commercial products are labeled "only for use in public health programs" and are not available for pest control management or agricultural use. Imports are banned, due to high levels of contaminants in the DDT available from other countries (especially China and India). Exports are regulated by Cicoplafest and every shipment is registered.

Technical Status of DDT in Mexico

Malaria was a major public health problem in Mexico from 1950 to 1989. The disease is endemic in more than 60 percent of the country's land area, a fact which is reflected in the high incidence and mortality statistics. The use of pesticides has markedly diminished the number of cases, from more than 120,000 per year to less than 5,000. Malaria mortality has declined sharply: it was one of the top ten causes of death in Mexico during the 1950s, but since 1982 there have been no deaths from the disease. These results show that an integrated approach is highly effective in the control of the vectors responsible for the spread of malaria and dengue fever. The low acute toxicity for humans has also promoted the use of DDT.

Public health programs involve a large number of workers, with more than 10 percent of the Health Ministry workforce currently involved in malaria control. More than 7,000 workers have been trained and equipped for DDT household spraying. The investment is considerable, with the exception of the pesticide, substitutes for which are seven or eight times more expensive. The employment of DDT substitutes has been ineffective and sporadic. It has been stated that DDT should be replaced by another pesticide, but in fact a more integrated approach to vector control is required.

In 1995, Mexico decided that an integrated pest management for malaria could substitute for the heavy reliance on pesticides. Improved sanitation, epidemiological surveillance and a minimum use of pesticides to control adult mosquitoes and larvæ are considered key elements. When the CEC began working on limiting human exposure to toxic and persistent substances, DDT became one of the four initial targets.

Reduction of human and environmental exposure to DDT will be accomplished through a gradual organized approach that will focus on:

• Elimination of illegal uses of DDT. Information is available that DDT might be being used for agricultural applications. Cicoplafest will reinforce surveillance in the southern states to ensure that spraying of DDT in the environnment is banned.
• Gradual reduction of DDT use for malaria control. The integrated approach will focus on reducing the number of foci of persistent transmission. The CEC will work with the North American Working Group on the Sound Management of Chemicals to assist in the monitoring and assessment of this program to help ensure that adequate population protection is maintained throughout the program. The amount of DDT used will be reduced by 80 percent (by volume) over five years and its total elimination is programmed over the next ten years.
• A region-wide approach. There is a continuous migration of population from Central America to several regions in Mexico and through Mexico to the United States. Thus, a successful approach to controlling DDT use should also consider the need for regional involvement to minimize transmission.
• Community involvement. Minimizing human and environmental exposure to DDT was the subject of a meeting of experts held in Mexico City, with the participation of Canada, the United States, PAHO and Mexico. The discussion attested to the success of the malaria control program in Mexico and concluded that further activities should encourage gradual reductions in DDT use through an integrated management approach.