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COMMUNITY
BUFFER STRIPS
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In Constanza two groups emerged from the study population who have vast
differences of opinion regarding pesticides, their application, and
heath risks. The first group, composed mostly of agribusiness corporate
class, believe that pesticides do not pose any risks to the environment
or community health. Their main concern was that a “pesticide
scare” would adversely affect their production goals. The vast
majority in this group live at a safe distance from pesticide application
and exposure. They also have options available to avoid pesticide exposure
during periods of heavy application.
The
second group is composed of poor landless farm workers, which make up
the vast majority of the study population. This group has limited options
to avoid pesticide exposure during periods of intense pesticide application.
They cope with pesticides by taking exposure preventive measures that
provide little if any protection from the toxic spray. These measures
include: closing windows and doors, covering gaps in walls with boards
and corrugated tin sheets, and seeking shelter at a neighbors home.
The latter offers little protection from exposure since community members
live within the pesticide dispersal zone. Against
this background, the principal policy recommendation is the creation
of health buffer strips in communities located within the pesticide
dispersal zone. The creation of the health buffer strips will be contingent
on three factors. First, the willingness of farm workers and their families
to participate in the creation of the buffers. Second, community members’
awareness that a pesticide problem exists and that buffers offers a
viable alternative for improving community health.
Third, willingness of landowners to donate part of their land
for the creation of the buffers. The
term buffer used in the study is defined as the distance needed for
improving community health. In other words, the distance between the
field edge of an area where pesticides are applied and nearest home
or school, in this case household clusters and community schools. By
this definition, the buffer zone starts at the field edge of the last
swath of pesticide spray. The average distance between field edge and
homes in the four communities are shown in Table 1. Prevalent wind
direction was plotted on the images to show potential pesticide
drift from adjacent fields.
Table 1
Distance from Field Edge to Pesticide Source
Source: Health Survey (Proximity Analysis), 2002
Gauging Community Willingness to Participate in Buffer Strip Creation SPSS was used to gauge the willingness of health survey respondents to participate in the creation of health buffers in their communities (See Tables 2-3). Table 2 shows that 76 out of the 101 health survey participants thought health buffers would provide a measurable degree of protection from pesticide exposure, leading to an improvement in community health. A significant number (N=24) said that the buffer zones would not improve community health. The majority of this group lived in low pesticide exposure risk communities. This group expressed feeling relatively safe from pesticide exposure because of distance between pesticide spray source and their homes. The notion of living at a safe distance from pesticide source gives community members a false sense of security. It was surprising, given this sense of security, that 18 respondents from Villa La Hortaliza said that they would participate in a buffer project. This could be attributed to their “visual exposure” to pesticide application. Unlike Barrio Lindo-El Gajo, which is surrounded by urban development, residents in Villa la Hortaliza have an open view of the nearby fields. Residents of Villa la Hortaliza are not as physically exposed to pesticides as the other two exposed communities but they share similar visual range. Table
3 shows that the vast majority (N=82) of survey participants said they
would be willing to participate in a buffer creation project in their
community. Another 24 said that they would not participate in a buffer
project. The majority of this group (N=15) live in Barrio Lindo-El Gajo,
which is the community located at the maximum distance from pesticide
source (2640’). The strong support for the proposed heath buffer strips
can be directly related to community members’ willingness to improve
environmental quality and community health. Surprisingly, willingness to participate in future buffer creation was high among both agribusiness and small farm owners, indicating an increased acceptance and support for health buffer zone creation (Tables 3-7). This is a significant finding since land donation is a key factor in the successful implementation of the proposed health buffer strips.
Table 2 Community Members Assessment of Buffer
Strip
Table 3 Health Survey Participants’ Willingness to Participate in Buffer
Strip Project
Table 4 Small Scale Farmers’ Willingness to Participate
in Buffer Strip Creation
Table 5 Small Scale Farmers’ Willingness to Donate Land For Buffer Strip Creation
Table 7 Agribusiness
Owners’ Willingness to Donate Land for Buffer Strip Creation
Selection of buffer strips was contingent on three factors: willingness of landowners to permanently
donate part of their land, the biogeophysical characteristics of the
sites, and severity of self-reported symptoms. Cholinesterase test results
were used as pesticide exposure biomarkers. The first step in buffer analysis was the creation of a relational
GIS database to store and query data. The database consists of various
data types obtained from Dominican Secretarias in both digitized and
non-digitized formats. The Secretaria de Estado de Agricultura facilitated
the use of their GIS Lab in Santo Domingo for digitizing and building
the GIS database. Arc View files
were obtained covering a period between 1984-1995.
Tireo and Colonia Kennedy Buffers Using the Tireo-El Café road
coverage and air photos
a buffer stripe was identified.
The buffer located along the Duran Highway is shown in these Figures.
Two sites were identified near Colonia
Kennedy. Both sites are empty plots that could serve as potential
resettlement land. A resettlement survey involving interviews with community
members (N=55) showed that the majority (N=46) are willing to participate
in a resettlement program. The survey population included both the health
survey population (N=25) and other community members (N=30) who live
in close proximity to field edge. The Dominican government owns site
2. The 200-tarea (31 acre) plot near the Duran highway was the site
of an ambitious government project to house military staff of the Cazadores
(Mountain) Battalion. Construction on the four high-rise apartment
buildings was stopped for lack of funding. This site is adjacent to
the Secretaria de Agricultura Regional Headquarters and the Japanese
Funded Organic Experimental Farm. Pesticide drift at the site is minimal
when compared with other parts of Colonia Kennedy and Tireo-El Café.
A tree buffer could provide additional protection from agricultural
drift coming in from the parcelas west of the Colonia Kennedy access
road.
Buffer Type The buffer type recommended for the three sites is known as a tree
buffer. Tree buffers are more effective in protecting human health from
the toxic effects of pesticides, in terms of the percentage of agrochemical
drift that can be filtrated. Tree buffers are capable of reducing pesticide
drift to over 70 percent (Interview with AgDrift Task Force Official,
2002). The health buffer strips proposed for the selected sites are not only
comprised of trees, but of shrubs and grasses as well. The row of trees
on the community side of the shelterbelt can be planted in fruit trees
such as mangoes, oranges, avocados, or grapefruit, which can produce
marketable products which can be harvested by community members for additional
household income. The spray side of the buffer can
be can be planted with fast growing trees (e.g., poplar, cottonwood,
eucalyptus, Dominican or Honduran pine) and shrubs. Tree species must
be selected not only based on their capacity to sequester pesticide
spray but on their resistance to pesticide spray. An additional consideration
is the tree’s susceptibility to insect damage. Figures 1-2 show the buffer layout for both communities. Buffer length
in Colonia Kennedy extends 0.7 mile, while in Tireo the buffer extends
1.3 miles. A 35-foot wide buffer
was selected due to land availability and the landowner’s landuse objectives.
The 35-foot buffer is divided into a 25-foot tree shelterbelt and 10-foot
no-spray buffer zone on the spray side of the shelterbelt (Figure 1).
Dilaha (et. al. 1989) found that 30 and 15 foot strips of orchard grass
trapped 84 and 70 percent of incoming pesticide residuals, respectively.
Magette found that 30 and 15-foot strips of fescue trapped 75 and 52
percent, respectively. Castelle et al, (1994) reviewed literature on
buffer and concluded that buffers from 10 to 650 feet were effective
depending on site-specific conditions.
Buffer Height and Porosity Buffer height and porosity were based on type of trees used and vegetation
density. Tree height was set at 50 feet and porosity at less than 70
percent using eucalyptus trees as an example. Tree spacing is critical
since inter-branching must be achieved in order to decrease porosity
(pesticide infiltration). To provide maximum protection form
drift, tree spacing for the selected tree species are set at 10 feet.
Gaps in the shelterbelt create
areas of high-wind velocity reducing the drift barrier effectiveness. Gaps
between the trees can be filled with shrubbery that have a high shade
tolerance. Figure 1 shows a tree shelterbelt with three rows of trees.
This buffer design is considered less porous due to interlocking leaves
and branches that reduce the size of gaps. Smaller gaps in the buffer
vegetation means less pesticide infiltration.
Figure 2 Buffer Configuration
The following shows the buffering
formula used to calculate buffer height and distance. The area of shelterbelt
protection is dependent on buffer height (tree height) and percentage
of pesticide infiltration or porosity. Shelterbelt protection was calculated
using the following formula:
Buffer Cost Buffer creation also involved determining the extent of farmland lost in the buffered area. Due to the cost and availability of land for buffer creation, the minimum buffer width and length were used. Based on the responses of landowners in the questionnaire, which tried to capture landowner receptivity and willingness to donate land for buffer creation, it is improbable that they will take out of production more than the recommended width and length. Landowner receptivity was given special consideration. The research looked at the acreage of productive agricultural farmland that would be affected by the creation of the recommended buffer strips. These landuse and ownership issues will weigh heavily in the outcome of buffer strip implementation.
Estimating Buffer Cost The Tireo-El Café buffer has a width of 35’ x 6,367’ length, which
is equivalent to 222,845 sq ft or 5.1 acres (43,560 sq ft in an acre).
The buffer would cross two parcelas that total approximately 320 acres
or ½ m2. In other words, creating the buffer zone could be cause for
removal of over 5.1 acres of the land from production. Each farm would
lose 2.5 productive farm acres. Estimated loss of earnings are not given
due to lack of reliable data provided by landowners. Depending on the
crop, the loss could fluctuate between 10,000 to 15,000 (US$) per year
(Personal interview with Secretaria de Estado de Agricultura Official,
2002). The author recognizes that the issue over land donation cannot depend on the “willingness and kindness” of landowners to take out of production prime farmland for buffer creation. This issue can be solved only by establishing mandatory buffer strips, considering that the source of contamination is the landowner’s fields. Nonetheless, recommendations offered in the area of community health improvement, must also attempt to bring about a change in behavior on the land itself, particularly pesticide application. In addition, any measures taken to protect community health must also consider changing landuse laws. This is easier said than done give the well-entrenched interests and powerful political connections of the agribusiness sector.
Summary of Results In summary, the major points in this section are (1) willingness to
participate in buffer strip creation among health survey participants;
(2) perception that health buffers will improve environmental quality
and community health; (3) willingness
of agribusiness and small farm owners to donate part of their land for
buffer creation; (4) acceptance of resettlement plan by community members
in Colonia Kennedy. In regards to the GIS buffer analysis, it successfully produced output
maps to display the recommended health buffers strips. While various
buffer widths were used, the
35-foot buffer was selected taking into consideration land availability
and minimum width required to provide protection from pesticide drift.
Although, pesticide drift has an obvious risk exposure impact on communities
located in close proximity to horticultural (vegetable) cultivated areas,
the magnitude of exposure varies with distances from pesticide source.
Buffer analysis appear to support two hypotheses: that creating buffer strips depends on
community participation and landowners’ willingness to donate land,
and that buffer strips may provide an effective barrier against pesticide
drift and can provide a “reasonable measure” of protection to communities
located in close proximity to pesticide source. The latter is also supported
by studies carried out by Wang and Takle 1995; Ucar and Hall 1999; Wang Takle 1997; Wang, Takle and Shen 2001; Teske and Thistle
2002; Teske, M. E., Ice, G. G., and Thistle, H. W. 2002; Teske,
Bird, Esterly, Curbishley, Ray and Perry 2002. A controversial issue that surfaced in
all these studies, in direct response to the creation of the buffer
strips, was creation of new landuse laws that would enable the government
to acquire land for buffer strip creation.
Conclusion The analytical methods used to estimate buffers do not guarantee there
will be no pesticide infiltration or exposure. They only estimate, taking
into consideration biogeophysical and socioeconomic factors, the most
conservative distance that can provide a reasonable certainty of no
harm. Whether buffer strips prove to be an effective barrier for toxic
pesticide exposure is indeterminate. The buffer strips recommended in this research are developed in the
context of desired human health and environmental quality improvement
goals, and therefore are subject to modification. Based on field observations
and surveys, the germane question should be whether reasonable certainty
of no harm to human health and environmental quality is safe enough.
It must be noted that buffers are only part of the solution. In addition,
responsible and safe application by well-trained farm workers is required.
Indiscriminate and wasteful pesticide application methods must be monitored
and corrected, preferably by community members. Buffering is just one of many viable and effective solutions available
to protect the health and well being of communities exposed to agrochemicals.
However, creating community buffer strips form part of a complete or
whole program. When implemented as a set of inter-related strategies,
they offer the most viable solutions for improving environmental quality
and protecting human health and well-being. In other words, when implemented
in isolation, buffers are not as effective in reducing agrochemical
spray drift. However, when buffering is combined with other strategies
and alternatives such as meteorological forecasting, biological or integrated
pest management, organic agriculture, and interspersed planting, the
outcome is an improved ecosystem that supports a healthier human-environment
relationship.
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