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Land, People and Environment The Problem The Research Geo-Cultural Visual Tour About Me and My Reserach Interests
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BIOGEOPHYSICAL
DATA ANALYSIS
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In August 1999, a detailed field survey was carried out to select communities based on biogeophysical characteristics and health conditions (See Tables 1, 2). Seven communities were selected and each location potted on a topographical map using ArcView.. The seven communities were divided into two groups based on the biogeophysical characteristics that contribute to greater or lesser pesticide exposure risk. Four communities were classified as having greater risk of pesticide exposure: Colonia Kennedy, Tireo-El Café, La Culata, and La Sabina. Three communities were classified as having lesser risk of pesticide exposure: Barrio Lindo-El Gajo, Villa La Hortaliza, and Palero. Of the seven communities surveyed, four (Colonia Kennedy, Barrio Lindo-El Gajo, Villa La Hortaliza, and Tireo-El Café) were selected for conducting the: Farm Worker Survey (1999-2000); Folk Healing Survey (2001-2002); and Health Survey (2002). The Topographical map shows the location of the four communities and the surrounding topographical (terrain) features.
Table 1 Criteria for Identifying Communities
Based on Biogeophysical Characteristics
Table 2 Criteria Used for Identifying Survey
Sample Potentially at Risk from Pesticide Exposure
Meteorological
Survey 1998-1999 This section discusses how biogeophysical setting and
meteorological conditions influence pesticide dispersal, and how
the combination of these factors influence community health. The
frequency of observed meteorological conditions in the region, during
a period extending from 1998-1999, were used to determine the influence
of wind speed and direction and fog on pesticide exposure (See Table
3). Because these data were incomplete, additional historical meteorological
observations were obtained from the Direccion Nacional de Meteorologia
(National Meteorological Office) in Santo Domingo. This data set
contained meteorological observations covering a period between
1970-1999. The software WRPLOT was used to make the wind plots
using both data sets. Information on each wind rose details the
frequency of occurrence of wind direction on a 16-point compass,
with north, east, south, and west directions going clockwise. The
wind rose plots were made in 2000 to depict monthly and annual wind
pattern variations. Results from wind rose analysis show that
the prevailing or dominant winds in the region blow from the NNE,
NE, E, and SE. However, in general, pesticide drift is often correlated
with the dominant transport direction of the wind. The wind rose
shown in the plots provided the best information regarding the percentage
of time the direction(s) and speed(s) associated with pesticide
drift, which can be expected over a period of time. The wind roses
plotted for Constanza were compared to pesticide drift trajectories
to obtain a qualitative assessment of how frequently pesticide drift
might be expected over a period of time. Based on these results,
the location and direction of the health buffers were plotted perpendicular
to incoming wind. Fog In the Constanza Region, ground fog or "radiation"
fog, is common. Radiation fog occurs when the air above the flat
valleys cools and becomes heavier forcing the cooler air down the
mountain slopes. This type of fog hugs the valley floor, often no
more than a couple of hundred feet thick. The heaviest fog was observed
in the Constanza and Tireo Valleys. Usually, fog lasts until mid-to-late
morning but on cloudy days it was observed until early afternoon. Table 3 Occurrence of Fog in Colonia Kennedy Observations Percent Non-Fog Days 41 39.8 Fog Days 62 60.2 Total 103 100
When clouds overlay fog, it prevents the ground from
heating by refracting heat back to the atmosphere. This means that
the fog will remain on the surface for longer periods. If pesticides
are applied when fog is present, pesticide particles will mix with
cloud condensation nuclei and will remain airborne for longer periods.
The combination of fog, cloud cover, temperature inversions and
pesticide application make for a deadly mixture. Fog conditions were more frequently observed in Tireo-El
Café, Colonia Kennedy and Villa La Hortaliza. In Barrio Lindo-El
Gajo, located adjacent the town of Constanza, fog was observed
rapidly breaking up in the early morning. This could be due to heating
of the surface caused by pavement and buildings. Fog was observed
burning off first in the valleys. Most of the fog that was recorded
dissipated first near the center of the valley and widened as the
morning progressed. The margins of the valley and lower slopes were
the last to burn off. The reason for this could be due to the region’s
complex mountain-valley circulations patterns.
Table 3 shows the frequency (60.2%) of observed fog
conditions in Colonia Kennedy in a 103-day period covering approximately
three months from November 1998 to February 1999. These results
indicate that fog is a common meteorological condition in the region,
and when coupled with pesticides, could have significant human health
implications. Pesticides, which are usually applied early in the
morning, can be dispersed over a large area for longer periods by
fog. As the fog moves, pesticide residues may again be available for transfer to the skin and respiratory system. In Colonia Kennedy, located above the valley floor, fog was a daily occurrence, lasting until late morning. Pesticide applicators were observed spraying the chemicals during fog conditions in Colonia Kennedy and Tireo-El Café. Applicators that spray during fog conditions may increase their chances of absorbing the suspended pesticide particles into their clothing and skin, providing an alternative contamination pathway for other members of their households. In addition, as the fog moves and shrouds nearby homes, the potential for exposure also increases. Based on my observations, the pesticide-laden mist penetrates through the gaps in the walls and door casings, settling on skin, clothing, and furnishing.
ENVIRONMENTAL QUALITY ANALYSIS 2002
Water Use in the Constanza Region Water use is controlled by the agribusiness sector.
Their farms received substantial allotments while the communities
go thirsty. The development of a massive system of irrigation canals
only benefits the large landowners who use over 70 percent of the
water resources (Sanchez 1999, Personal Communication). Adding insult
to injury, the massively developed irrigation network is extremely
inefficient. Irrigation canals require not only initial investment
for construction, but also continued capital inputs for upkeep,
and such additional funding is not available. The results are staggering.
An estimated 50 to 90 percent of the water diverted for irrigation
never reaches the fields, becoming absorbed into the earth in the
many unlined and poorly maintained canals. The water that does reach
the fields often achieves undesired results (Sanchez 1999, Personal
Communication). The constant use of field flooding as a means of
irrigation has over time led to the salinization of the soil. In
addition, some of the irrigated lands have become useless through
rising water tables. The picture of environmental disaster gets worse. As
land is lost, and as horticultural yields decrease, agribusiness
owners move to reverse the trend by increasing the use of pesticides.
Thus, after flowing through the fields, the water that remains is
heavily polluted. To combat resistant insects, the local authorities
apply 25 pounds of chemical per acre (Interview with Agronomist
in Tireo-El Cafe, 1999). The remaining polluted water constitutes
the only source of drinking water for many of the region's poor
population. In Upper Colonia Kennedy, mothers who bottle-feed their
infants using this polluted water source also run the risk of poisoning
them. In the entire region the drinking water crisis has become
particularly acute. Given the chemical cocktail contained in its
drinking water and the low state of health care, it is possible
that many of the symptoms attributed to pesticides are caused or
exacerbated by other agents or pathogens.
Water Quality Testing 2002 The specificity of the similarities between symptoms
and illnesses associated with pesticide poisoning and contaminated
water was questioned. It is possible that exposures to hydrogen
producing bacteria and nitrites-nitrates will produce a similar
constellation of symptoms as pesticide poisoning. All the water taken from home or community supplies
which were tested (N=101) using the Hach Patho Screen were contaminated
with hydrogen sulfide producing bacteria which may include Salmonella,
Citrobacter, Proteus, Edwardsiella, and some species of Klebsiella.
Water Quality Test: Nitrite-Nitrate Nitrate
is a water-soluble molecule made up of nitrogen and oxygen. As an
essential component of life, nitrogen is recycled continually by
plants and animals, and is found in the cells of all living things.
Nitrate is also a major ingredient of farm fertilizer and is necessary
for crop production. When it rains, varying nitrate amounts wash
from farmland into nearby waterways. Pesticides used in conjunction
with fertilizers may be carried into ground water in the same way
as nitrate. Detection of nitrate in ground water may indicate the
presence of pesticides, although a number of additional factors
complicate this relationship. The Environmental Protection Agency
(EPA) has adopted the 10-mg/L standard as the maximum contaminant
level (MCL) for nitrate-nitrogen and 1 mg/L for nitrite-nitrogen
for regulated public water systems (EPA Web Site, 2002). It is difficult
to establish an exact level at which nitrogen concentrations in
water are safe or unsafe. The intake of nitrogen from food and other
sources also is important and must be considered. Nitrate is also a major ingredient of farm fertilizer
and is necessary for crop production. When it rains, varying nitrate
amounts wash from farmland into nearby waterways. Pesticides used
in conjunction with fertilizers may be carried into ground water
in the same way as nitrate. Detection of nitrate in ground water
may indicate the presence of pesticides, although a number of additional
factors complicate this relationship. The Environmental Protection
Agency (EPA) has adopted the 10-mg/L standard as the maximum contaminant
level (MCL) for nitrate-nitrogen and 1 mg/L for nitrite-nitrogen
for regulated public water systems (EPA Web Site, 2002). It is difficult
to establish an exact level at which nitrogen concentrations in
water are safe or unsafe. The intake of nitrogen from food and other
sources also is important and must be considered. Results from the nitrate / nitrite samples tested show
that all four communities have a high percentage of drinking water
samples containing nitrates/nitrites. There are two main potable
water sources for the communities and town of Constanza; both water
sources (aquifers) are surrounded by cultivated farmland, which
are dependent on intense pesticide applications. Run off from the
fields into the aquifer is the likely source of contamination.
Table 4 show that 69 households in the four communities
(69.6%) are drinking water containing nitrates. The samples that
tested negative for nitrite and nitrate (N=29) were from households
that purchase bottled water or traveled to natural springs to collect
water. Some of the water samples that tested positive (N=69) were
purchased (bottled) or self-collected water. This could be attributed
to improper rinsing of empty bottles before refilling. In the case of Villa La Hortaliza, 22 samples tested
positive for nitrates, higher than communities with greater pesticide
exposure risk. Community members get their drinking water from
a pozo tubular or well, located in a high pesticide application
area approximately ½ mile from the community. Water samples taken
at the well tested positive for both nitrate and nitrite. Table 4 Water Quality Test Results
for Nitrate Community N/A Present Absent Total Barrio Lindo-El Gajo 3 9 14 26 Colonia Kennedy 19 6 25 Tireo-El Café 19 6 25 Villa La Hortaliza 22 3 25 Total 3 69 29 101 Source: Environmental Survey, 2002 Testing for Hydrogen Sulfide Producing Bacteria,
2002 In the study region, people come in contact with different
pathogens in drinking water or in rivers and streams where they
bathe. Many of the gastrointestinal symptoms reported by health
survey participants, that they attributed to pesticides, could have
been caused by contaminated water or a combination of the two. Table
5 shows that approximately 70 percent of the water samples (N=101)
tested positive for hydrogen producing bacteria. The implication
of the high percentage of contaminated water indicates that many
of the self-reported symptoms of gastrointestinal origin, recorded
in the health survey, might be caused by poor water quality and
not pesticide exposure. Villa La Hortaliza had the highest number of samples
testing positive for hydrogen producing bacteria. Water samples
taken at the well showed no contamination. However, observation
of household behavior revealed that disinfective agents are not
used to clean water receptacles, paving the way for bacterial growth. Table 5 Water Quality Test Result
for Hydrogen Producing Bacteria Community N/A2 Positive Negative Total Colonia Kennedy 6 13 7 26 Tireo-El Café
19 6 25 Villa La Hortaliza 5 17 3 25
21 4 25 11 70 20 101 Source: Environmental Survey, 2002 Another major concern is that the combination of poor
water quality and pesticides may weaken the immune system, leaving
the individual vulnerable to opportunistic diseases. One study links
pesticides with weakened immune response to invading viruses, bacteria,
and parasites, many of which are found in contaminated water (Repetto
and Baliga, 1996: 1). As the body’s first line of defense, a weakened
immune system could increase the number of people that succumb to
otherwise preventable and treatable diseases.
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