NORTH AMERICAN REGIONAL ACTION PLAN ON DDT NORTH AMERICAN WORKING GROUP FOR THE
SOUND MANAGEMENT OF CHEMICALS TASK FORCE ON DDT AND CHLORDANE
June 1997
Table of Contents
1.0 Introduction
1.1 Objective
1.2 Guiding Principle
1.3 Rationale
2.0 Background
2.1 Canada
2.2 The United States
2.3 Mexico
3.0 Goals
4.0 Actions
4.1 Specific NARAP Actions
4.1.1 Alternative Vector Controls
4.1.2 Public Health
4.1.3 Public Participation and Education Activities
4.1.4 Industrial Sector
4.1.5 Enforcement
4.1.6 Waste Management
4.1.7 Integration with International Activities
4.1.8 Implementation
4.1.9 Reporting
5.0 Appendix-Presentation by the Mexican Ministry of Health
5.1 Introduction
5.2 Aspects of Malaria Prevention and Control Programs in Mexico
5.3 Program activities
5.4 Current Legal Status of DDT Production and Use in Mexico
5.5 Technical Status of DDT in Mexico
1.0 Introduction
1.1 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.
1.2 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.
1.3 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.
2.0 Background
2.1 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.
2.2 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.
2.3 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.
3.0 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:
- minimize movement of malaria-infected populations across borders
and
- reduce the illegal importation of DDT.
- Cooperation in international fora will be increased to advance
global controls on DDT production, export and use.
4.0 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.
4.1 Specific NARAP Actions
4.1.1 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:
A) 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.
B) 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.
C) 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.
D) 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.
4.1.2 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:
A) 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).
B) 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.
4.1.3 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.
A) 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.).
B) Community participation will be sought for the development
and implementation of the projects, and to ensure that local community
organizations are kept informed.
C) Additional information about illegal DDT use in agriculture
and guidance and advice on alternative practices will be provided.
D) Effective ways of disseminating information and educational
materials will be developed.
4.1.4 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);
- 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.
4.1.5 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.
4.1.6 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.
4.1.7 Integration with International Activities
A) 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.
B) 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.
C) 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.
D) As appropriate, the relevant international organizations will
be involved.
E) 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.
F) 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.
4.1.8 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.
4.1.9 Reporting
A) 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.
B) 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.
5.0 Appendix-Presentation by the Mexican Ministry of Health
5.1 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.
5.2 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:
- For non-priority states: Intensification of epidemiological
surveillance, selective application of DDT spraying to dwellings,
and intensive treatment of diagnosed cases.
- 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.
5.3 Program 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.
5.4 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.
5.5 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.
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