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"SILENT
SPRING" IN CONSTANZA
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Pesticides:
A Necessary Evil
What Are Agrochemicals? Because the broad terms agrochemicals and pesticides
encompass a diverse collection of substances, an explanation of pesticide
taxonomy and nomenclature is warranted. Pesticides can be classified
either by target pest or by chemical identity. Classification by target
pest is perhaps the most familiar. For example, insecticides are pesticides
that target insects, and herbicides target plants. There are many more
examples: acaricides target ticks, nematocides target nematodes, etc.
What is important to note, for the purposes of this Chapter, is that
9 of the 13 pesticides of concern (Table 2) have been classified by
the EPA as highly toxic (Table 1). Table 2 and Figure 1 shows the most
commonly used pesticides in the Constanza Region.
Table 1 EPA
Pesticide Toxicity Classes
Source: EPA 2001 Table 2 Most
Commonly Used Agrochemicals in the
Constanza Region 2002
Pesticides can also be organized by their chemical class.
A pesticide class is a group of pesticide compounds that share a common
chemistry. For example, all pesticides in the class organophosphate
(OP) are derivatives of phosphoric acid, and all pesticides in the class
organochlorine are composed of carbon, hydrogen, and chlorine. There
are also chemical subclasses of pesticides, but these are beyond the
scope of this Chapter. Only the three classes of agrochemicals, commonly
used in the study region, are discussed: organophosphates, organochlorines,
and carbamates. With time, pesticides may break down, be redistributed within the application site or move off site. Off site movement includes movement to groundwater, surface water, and the atmosphere. Break down and movement occur simultaneously. In many cases, the two processes together determine pesticide dispersion at the point of measurement (Karalliedde, Feldman, Henry and Marrs 2001). How long a pesticide lasts in the environment is determined
by a number of factors including: (1) how much is introduced and how
it is distributed; (2) its reactivity in the environmental media; and
(3) the conditions of the media. Pesticide persistence is often expressed
in terms of half-life (Ordish 1976). This is the time required for one-half
the original quantity to break down. Pesticides can be divided into
3 categories based on half-lives: (1) non persistent--less than 30 days;
(2) moderately persistent--30 to 100 days; and (3) persistent--greater
than 100 days. Because half-life values can vary considerably depending
on environmental conditions, they are often reported as a range for
each medium (Karalliedde, Feldman, Henry and Marrs 2001).
Agrochemicals Most Commonly Used in
Constanza Organochlorine Pesticides
Pesticide Drift Dynamics Pesticide droplet size is measured in microns (µm).
Pesticide droplets smaller than 100 µm are considered highly driftable.
By comparison, a dime is about 1,270 microns thick (Telephone Interview
with AgDrift Task Force, 2002). Droplets
smaller than 100 µm pesticide droplet droplets are so small they cannot
be seen unless in high concentrations, such as fog (See Table 3). Because
of the small droplet size, drift is more dependent on air movement than
on gravity. Small pesticide droplets are suspended in the atmosphere
longer and fall through the air slowly. The smaller the droplet size,
the greater the distance they are transported from the intended target.
The main transport agent for pesticide droplets is air movement. Table
3 Shows the effect of droplet size on the rate of fall. The longer the
droplet is airborne, the greater the potential for drift.
Table 3
Droplet Size and Drift
Pesticide Application Methods Backpack Spraying By far the most common pesticide application equipment used in the study region is the backpack sprayer, which are used to apply pesticides on smaller parcelas. Backpack sprayers are inexpensive and consists of three major parts: a tank to hold the spray mix, a pump to provide pressure, and a nozzle/wand to deliver the chemical in the desired spray pattern (See Figures 6.2).
Figure 2
Backpack Pesticide Sprayer
Figure 3 Applying Pesticide Near Colonia Kennedy
The Effects of Pesticide Applicators
and Mixers Decision Making on Agrochemical Drift and Exposure The crop and size of the parcelas to be sprayed dictates
the time spent in the field, and rate and intensity of each application.
This gives little time for careful label reading and following the manufacturer’s
instructions on the “safe” use of the chemical. This is influenced by
the reading skills of the applicator and mixer. If the applicator and
mixer cannot read, inappropriate chemical mixing and application are
assured. Another problem influencing proper use and disposal of pesticides
is that labels are not written in Spanish.
Consequently, cells are excessively stimulated. The
increase in ACh action leads to symptoms characteristic of increased
ACh activity at peripheral and, to varying degrees, central ACh receptors,
which fall largely into two classes, nicotinic and muscarinic (Kaloyanova
and El Batawi 1991). Symptoms that occur acutely with OP (and carbamate) toxicity can span a range from mild tremors to more severe muscle contractions, impaired cognition, dizziness, shortness of breath, and vomiting. In severe cases, respiratory failure and death can result. The severity of symptoms is related to the amount and route of exposure. Acute toxicity for both OP and carbamate poisoning may be complicated by ventricular arrhythmias, CNS depression, seizures, or respiratory failure; and relapse may occur after seemingly successful treatment (Edwards 2001). Additional problems with acute toxicity that have been described less frequently include renal failure, which may be associated with proteinuria (Albright et al. 1983; Wedin et al. 1984), and pancreatitis, which has been reported to occur with exposure to AChE-inhibiting pesticides. Most of what is known about symptoms associated with
acute exposures to pesticides, including OPs, comes from studies of
patients who were involved in accidental exposures or mishandling/misapplication
of pesticides. For example, Saadeh et al. 1996) evaluated clinical manifestations
of 70 adult patients (33 males, 37 females) in North Jordan who were
admitted to a teaching hospital for acute carbamate or OP poisoning
associated with accidents, suicide attempts, or occupational exposures. Comparatively non-persistent symptoms (i.e., they had typically resolved by 10 weeks) included nausea, dizziness, vomiting, abdominal pain, ataxia, and night sweats or insomnia. Symptoms that persisted in at least three of the 16 subjects at 10 weeks or more included blurred vision/vision disturbance (56 percent), headache (25 percent), anxiety (41 percent), weakness, and anorexia. Symptoms persisted for up to 10 weeks, varying by symptom and individual. Six of the subjects initially had RBC AChE values within the normal laboratory range, but follow-up testing showed activity to have been significantly inhibited.
Effects of Pesticides on Human Immune,
Neurological and Endocrine Systems
Figure 4 The Endocrine System
Not all endocrine disruptors are synthetic chemicals, some are natural phytoestrogens, such as those found in soy products. By acting on the endocrine system they mimic, block and/or interfere in some manner with the natural function of hormone receptor cells. They interfere with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body, which are responsible for the maintenance of homeostasis, reproduction, development, and/or behavior (Kavlock et al. 1996:714-740). The impact of endocrine disruptors on immune system function and disease resistance is poorly understood. At best we have a very preliminary understanding of what may be going on. There are hints, nonetheless, that this may be one of the most important and far reaching routes by which endocrine disrupting chemicals undermine human health. Several studies and reviews (Harris 2000; Ecobichon 1999; Repetto and Baliga 1997; Jeyaratnam and Chia 1994; Kaloyanova and El Batawi 1991; Mineau et al. 1991) indicate that contaminants can erode disease resistance in ways that make people mortally vulnerable to infectious diseases they might otherwise have been able to resist. The importance
of contaminant effects on health may have been vastly under-estimated,
because disease statistics would attribute the death to the infectious
agent, whereas it would not have occurred without contamination. A new
paradigm for studying and preventing many infectious diseases may emerge,
in which you need first to understand the contamination history and
status of the person exposed to an infectious disease.
Table 4 Serum
and Urine Tests to Detect Pesticides and their Metabolites
Source: EPA and Pesticide Network (Personal Communication 2002)
Table 5 Personal Protective Equipment (PPE) Requirement for Pesticide Mixers and Applicators
Figure 5 Common Pesticides Application Methods in Constanza
Agribusiness and Agrochemicals: Risking Workers Health and Well-Being Agribusiness With well over 95% of Constanza’s agribusiness farms reliant on agriculture for their livelihood, the market for pesticides is enormous (See Figure 5). Although some agribusiness owners believe that pesticides are the main cause of the environmental problems in the region, the majority believes that they are a miracle ally in the war against pests. Their strong connections in Santo Domingo guarantee that horticultural production will continue despite pressures from communities clamoring for improved environmental quality and community health. Although agribusiness owners are well informed about the toxic hazards of the chemicals that are sprayed on their land, they chose to ignore the risks they pose to their workers. Few of the poorly educated and impoverished farmers, applicators and mixers realize how dangerous these chemicals are (Interview/Questionnaire 1998, 1999, 2002).
The Chemical Industry In the developing world between the mid-1980s and mid-1990s,
agricultural production and fertilizer use both increased by almost
42 percent, the latter from an average of 63 kilos per hectare of cropland.
Consumption of fertilizers and its growth were highest in Asia, while
in Africa usage has actually fallen since the 1980s– from 19 kilos per
hectare to 18. The Food and Agriculture Organization of the United Nations
(FAO) predicts further rises in the developing world, probably of around
2.8 percent per year from current levels of almost 99 kilos of fertilizer
per hectare of cropland.
Figure 6 Agrochemical
Use (Fertilizers)
The pesticide chemical industry denies responsibility for what happens to their products after leaving their docks. They are secure in the knowledge that there will be no lawsuits when 10 or 30 people die in Constanza from exposure to their chemicals. They are just as aware that the Dominican Republic lacks an environmental protection secretaria, and that farm workers and their families will have no other alternative but to accept pesticide exposure as part of the risks of living and working in a contaminated environment. There are environmental groups that are challenging the chemical industry and those that purchase their products. These environmental organizations are struggling to build regulatory capacity in an attempt to control illicit trade and use of pesticides. But they are no match for the massive commercial pressure coming from inside and outside Dominican borders.
Figure 7
Agrochemical Trade
One of the world’s largest pesticide chemical manufacturer is the Swiss company Novartis (formerly Ciba Geigy) (Dinham 1993). Novartis holds the dubious honor of having discovered the pest control uses of DDT, and of marketing the poisonous pesticide worldwide (Table 6). Dinham argues that “an accurate assessment of the numbers of people affected by pesticide use and misuse is impossible” (1993:2). In 1990, the World Health Organization (WHO) estimated that there were a minimum of three million acute severe cases of pesticide poisonings and 20,000 unintentional deaths each year, mostly in the Third World (Jeyaratnam 1990). Developing countries use only 20 percent of the World’s agrochemicals yet they suffer 99 percent of deaths from pesticide poisoning (Jeyaratnam and Chia 1994). Karalliedde notes that “deliberate self-poisoning by drinking pesticides is a phenomenon that is predominantly seen in South East Asia, the Indian subcontinent, and expatriate Indian communities worldwide” (2001:431). The author also notes that poisoning was amongst the three leading causes of hospital deaths in Sri Lanka and nearly 15,000 admissions following carbamate exposure. Over 80 percent of the poisonings (with OPs) in Sri Lanka result from intentional oral intake with suicidal intent (Senanayake 1998). Jeyaratnam’s (et al., 1982) research showed that “…patients with pesticide poisoning admitted to Sri Lankan hospitals showed that 73 percent were suicidal, 17 percent occupational and 8 percent accidental” (Karalliedde and Eddleston 2001:431). Numerous other studies show that pesticides are used to commit suicide (Abebe 1991; McConnell and Hruska 1993; Litovitz et al. 1997; Gupta et al. 1998). In the Constanza Region, the use of pesticide to commit suicide is not common among adults and rarely seen in children. Instead, children are more commonly victims of accidental poisoning. While Novartis no longer produces DDT, it sells toxic agrochemicals to countries like the Dominican Republic under different trade names. Many of these pesticides have been labeled by the EPA as Class I (Table 1). Remarkably, pesticide manufactures test their products using farm workers as subjects. The World Health Organization has stated that each year 3 million people are treated for the effects of organophosphate poisoning of whom 20,00-40,000 die (Karalliedde 2001). However, Jeyaratnam (1990) estimates that 25 million farm workers are exposed to pesticides in the Third World, many of these are acutely poisoned every year. Despite these figures, pesticide manufactures continue to produce agrochemicals, which, according to the Washington, D.C.-based National Coalition Against the Misuse of Pesticides, are acutely toxic substances when absorbed orally or through the skin (Interview with Official 2001, 2002). The Dominican government continues to allow the import
of these toxic chemicals despite the evidence of their effects on humans
and the environment. With no regulatory agency in place to monitor pesticide
import and use, these toxic chemicals will continue to make their way
into study region. Agrochemical corporations are cultivating relationships
with the Secretaria de Estado de Agricultura (Ministry of Agriculture),
to secure future sales of their
products. Agrochemical companies have even embarked in aggressive campaigning
to promote their products. They
hold courses and seminars in some of the country’s agricultural schools,
including a series of talks on the uses of chemicals in agriculture.
The research expresses concern that the link between Novartis and the
country’s agricultural research centers will create an atmosphere for
promoting pesticides rather than non chemical methods of pest control.
Table 6 Major
Pesticide Corporations and their Countries of Origin, 1990 and 1991
Sales
Dominican Policy Makers, Pesticide Use and Exposure They are responsible for passing laws that prohibit the import of Class I and II pesticides into the country (Table 1). They are responsible for ensuring that proper labels and instructions for pesticide use and disposal are provided and that they can be used with a reasonable certainty of no harm to human health and environmental resources. In fulfilling these duties, Dominican policy makers have the moral obligation to consider the potential impact of pesticide spray drift on its citizens and the environment. In the case of the study area, more often than not, policy makers are part of the problem and not the solution. With large tracts of land owned by government officials, who supplement their meager government income with profits made from commercial farming, it is hard to imagine policies and laws being drafted that limit pesticide use. Taking into consideration the importance of agribusiness production in the region’s economy, human health and environmental quality improvement are not on the political agenda.
Conclusion
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